diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh index 5dc3f671..756b22d7 100644 --- a/include/qpdf/QPDF.hh +++ b/include/qpdf/QPDF.hh @@ -391,7 +391,7 @@ class QPDF void replaceObject(int objid, int generation, QPDFObjectHandle); // Swap two objects given by ID. Prior to qpdf 10.2.1, existing QPDFObjectHandle instances that - // reference them objects not notice the swap, but this was fixed in 10.2.1. + // reference the objects did not notice the swap, but this was fixed in 10.2.1. QPDF_DLL void swapObjects(QPDFObjGen const& og1, QPDFObjGen const& og2); QPDF_DLL @@ -645,7 +645,7 @@ class QPDF QPDF_DLL void fixDanglingReferences(bool force = false); - // Return the approximate number of indirect objects. It is/ approximate because not all objects + // Return the approximate number of indirect objects. It is approximate because not all objects // in the file are preserved in all cases, and gaps in object numbering are not preserved. QPDF_DLL size_t getObjectCount(); @@ -730,10 +730,10 @@ class QPDF class Writer; class Resolver; class StreamCopier; + class Objects; class ParseGuard; class Pipe; class JobSetter; - class Xref_table; // For testing only -- do not add to DLL static bool test_json_validators(); @@ -748,7 +748,6 @@ class QPDF static std::string const qpdf_version; - class ObjCache; class ObjCopier; class EncryptionParameters; class ForeignStreamData; @@ -757,36 +756,15 @@ class QPDF class ResolveRecorder; class JSONReactor; + inline Objects& objects() noexcept; + inline Objects const& objects() const noexcept; void parse(char const* password); void inParse(bool); void setLastObjectDescription(std::string const& description, QPDFObjGen const& og); - QPDFObjectHandle readObject(std::string const& description, QPDFObjGen og); - void readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset); - void validateStreamLineEnd(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset); - QPDFObjectHandle readObjectInStream(std::shared_ptr& input, int obj); - size_t recoverStreamLength( - std::shared_ptr input, QPDFObjGen const& og, qpdf_offset_t stream_offset); QPDFTokenizer::Token readToken(InputSource&, size_t max_len = 0); - QPDFObjectHandle readObjectAtOffset( - bool attempt_recovery, - qpdf_offset_t offset, - std::string const& description, - QPDFObjGen exp_og, - QPDFObjGen& og, - bool skip_cache_if_in_xref); - QPDFObject* resolve(QPDFObjGen og); - void resolveObjectsInStream(int obj_stream_number); void stopOnError(std::string const& message); - QPDFObjGen nextObjGen(); QPDFObjectHandle newIndirect(QPDFObjGen const&, std::shared_ptr const&); - QPDFObjectHandle makeIndirectFromQPDFObject(std::shared_ptr const& obj); - bool isCached(QPDFObjGen const& og); - bool isUnresolved(QPDFObjGen const& og); - std::shared_ptr getObjectForParser(int id, int gen, bool parse_pdf); - std::shared_ptr getObjectForJSON(int id, int gen); - void removeObject(QPDFObjGen og); - void updateCache(QPDFObjGen const& og, std::shared_ptr const& object); static QPDFExc damagedPDF( InputSource& input, std::string const& object, @@ -831,8 +809,7 @@ class QPDF void optimize( QPDFWriter::ObjTable const& obj, std::function skip_stream_parameters); - void optimize(Xref_table const& obj); - size_t tableSize(); + void optimize(Objects const& obj); // Get lists of all objects in order according to the part of a linearized file that they belong // to. @@ -852,12 +829,6 @@ class QPDF int& O, bool compressed); - // Get a list of objects that would be permitted in an object stream. - template - std::vector getCompressibleObjGens(); - std::vector getCompressibleObjVector(); - std::vector getCompressibleObjSet(); - // methods to support page handling void getAllPagesInternal( @@ -931,7 +902,7 @@ class QPDF QPDFObjectHandle getUncompressedObject(QPDFObjectHandle&, std::map const& object_stream_data); QPDFObjectHandle getUncompressedObject(QPDFObjectHandle&, QPDFWriter::ObjTable const& obj); - QPDFObjectHandle getUncompressedObject(QPDFObjectHandle&, Xref_table const& obj); + QPDFObjectHandle getUncompressedObject(QPDFObjectHandle&, Objects const& obj); int lengthNextN(int first_object, int n); void checkHPageOffset(std::vector const& pages, std::map& idx_to_obj); @@ -977,7 +948,7 @@ class QPDF std::function skip_stream_parameters); void filterCompressedObjects(std::map const& object_stream_data); void filterCompressedObjects(QPDFWriter::ObjTable const& object_stream_data); - void filterCompressedObjects(Xref_table const& object_stream_data); + void filterCompressedObjects(Objects const& object_stream_data); // JSON import void importJSON(std::shared_ptr, bool must_be_complete); diff --git a/libqpdf/CMakeLists.txt b/libqpdf/CMakeLists.txt index eb30b622..189e506e 100644 --- a/libqpdf/CMakeLists.txt +++ b/libqpdf/CMakeLists.txt @@ -107,6 +107,7 @@ set(libqpdf_SOURCES QPDF_encryption.cc QPDF_json.cc QPDF_linearization.cc + QPDF_objects.cc QPDF_optimization.cc QPDF_pages.cc QTC.cc diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc index 12b23a8d..cc54db29 100644 --- a/libqpdf/QPDF.cc +++ b/libqpdf/QPDF.cc @@ -2,10 +2,8 @@ #include -#include #include #include -#include #include #include #include @@ -187,7 +185,7 @@ QPDF::Members::Members(QPDF& qpdf) : file_sp(new InvalidInputSource(no_input_name)), file(file_sp.get()), encp(new EncryptionParameters), - xref_table(qpdf, file) + objects(qpdf, this, file) { } @@ -201,25 +199,7 @@ QPDF::QPDF() : m->unique_id = unique_id.fetch_add(1ULL); } -QPDF::~QPDF() -{ - // If two objects are mutually referential (through each object having an array or dictionary - // that contains an indirect reference to the other), the circular references in the - // std::shared_ptr objects will prevent the objects from being deleted. Walk through all objects - // in the object cache, which is those objects that we read from the file, and break all - // resolved indirect references by replacing them with an internal object type representing that - // they have been destroyed. Note that we can't break references like this at any time when the - // QPDF object is active. The call to reset also causes all direct QPDFObjectHandle objects that - // are reachable from this object to release their association with this QPDF. Direct objects - // are not destroyed since they can be moved to other QPDF objects safely. - - for (auto const& iter: m->obj_cache) { - iter.second.object->disconnect(); - if (iter.second.object->getTypeCode() != ::ot_null) { - iter.second.object->destroy(); - } - } -} +QPDF::~QPDF() = default; std::shared_ptr QPDF::create() @@ -280,7 +260,7 @@ QPDF::emptyPDF() { m->pdf_version = "1.3"; m->no_input_name = "empty PDF"; - m->xref_table.initialize_empty(); + m->objects.xref_table().initialize_empty(); } void @@ -293,7 +273,7 @@ QPDF::registerStreamFilter( void QPDF::setIgnoreXRefStreams(bool val) { - m->xref_table.ignore_streams(val); + m->objects.xref_table().ignore_streams(val); } std::shared_ptr @@ -331,7 +311,7 @@ void QPDF::setAttemptRecovery(bool val) { m->attempt_recovery = val; - m->xref_table.attempt_recovery(val); + m->objects.xref_table().attempt_recovery(val); } void @@ -409,17 +389,6 @@ QPDF::findHeader() return valid; } -bool -QPDF::findStartxref() -{ - if (readToken(*m->file).isWord("startxref") && readToken(*m->file).isInteger()) { - // Position in front of offset token - m->file->seek(m->file->getLastOffset(), SEEK_SET); - return true; - } - return false; -} - void QPDF::parse(char const* password) { @@ -436,9 +405,9 @@ QPDF::parse(char const* password) m->pdf_version = "1.2"; } - m->xref_table.initialize(); + m->objects.xref_table().initialize(); initializeEncryption(); - if (m->xref_table.size() > 0 && !getRoot().getKey("/Pages").isDictionary()) { + if (m->objects.xref_table().size() > 0 && !getRoot().getKey("/Pages").isDictionary()) { // QPDFs created from JSON have an empty xref table and no root object yet. throw damagedPDF("", 0, "unable to find page tree"); } @@ -478,1059 +447,10 @@ QPDF::warn( warn(QPDFExc(error_code, getFilename(), object, offset, message)); } -void -QPDF::Xref_table::initialize_empty() -{ - initialized_ = true; - trailer_ = QPDFObjectHandle::newDictionary(); - auto rt = qpdf.makeIndirectObject(QPDFObjectHandle::newDictionary()); - auto pgs = qpdf.makeIndirectObject(QPDFObjectHandle::newDictionary()); - pgs.replaceKey("/Type", QPDFObjectHandle::newName("/Pages")); - pgs.replaceKey("/Kids", QPDFObjectHandle::newArray()); - pgs.replaceKey("/Count", QPDFObjectHandle::newInteger(0)); - rt.replaceKey("/Type", QPDFObjectHandle::newName("/Catalog")); - rt.replaceKey("/Pages", pgs); - trailer_.replaceKey("/Root", rt); - trailer_.replaceKey("/Size", QPDFObjectHandle::newInteger(3)); -} - -void -QPDF::Xref_table::initialize_json() -{ - initialized_ = true; - table.resize(1); - trailer_ = QPDFObjectHandle::newDictionary(); - trailer_.replaceKey("/Size", QPDFObjectHandle::newInteger(1)); -} - -void -QPDF::Xref_table::initialize() -{ - // PDF spec says %%EOF must be found within the last 1024 bytes of/ the file. We add an extra - // 30 characters to leave room for the startxref stuff. - file->seek(0, SEEK_END); - qpdf_offset_t end_offset = file->tell(); - // Sanity check on object ids. All objects must appear in xref table / stream. In all realistic - // scenarios at least 3 bytes are required. - if (max_id_ > end_offset / 3) { - max_id_ = static_cast(end_offset / 3); - } - qpdf_offset_t start_offset = (end_offset > 1054 ? end_offset - 1054 : 0); - PatternFinder sf(qpdf, &QPDF::findStartxref); - qpdf_offset_t xref_offset = 0; - if (file->findLast("startxref", start_offset, 0, sf)) { - xref_offset = QUtil::string_to_ll(read_token().getValue().c_str()); - } - - try { - if (xref_offset == 0) { - QTC::TC("qpdf", "QPDF can't find startxref"); - throw damaged_pdf("can't find startxref"); - } - try { - read(xref_offset); - } catch (QPDFExc&) { - throw; - } catch (std::exception& e) { - throw damaged_pdf(std::string("error reading xref: ") + e.what()); - } - } catch (QPDFExc& e) { - if (attempt_recovery_) { - reconstruct(e); - QTC::TC("qpdf", "QPDF reconstructed xref table"); - } else { - throw; - } - } - - initialized_ = true; -} - -void -QPDF::Xref_table::reconstruct(QPDFExc& e) -{ - if (reconstructed_) { - // Avoid xref reconstruction infinite loops. This is getting very hard to reproduce because - // qpdf is throwing many fewer exceptions while parsing. Most situations are warnings now. - throw e; - } - - // If recovery generates more than 1000 warnings, the file is so severely damaged that there - // probably is no point trying to continue. - const auto max_warnings = qpdf.m->warnings.size() + 1000U; - auto check_warnings = [this, max_warnings]() { - if (qpdf.m->warnings.size() > max_warnings) { - throw damaged_pdf("too many errors while reconstructing cross-reference table"); - } - }; - - reconstructed_ = true; - // We may find more objects, which may contain dangling references. - qpdf.m->fixed_dangling_refs = false; - - warn_damaged("file is damaged"); - qpdf.warn(e); - warn_damaged("Attempting to reconstruct cross-reference table"); - - // Delete all references to type 1 (uncompressed) objects - for (auto& iter: table) { - if (iter.type() == 1) { - iter = {}; - } - } - - std::vector> objects; - std::vector trailers; - int max_found = 0; - - file->seek(0, SEEK_END); - qpdf_offset_t eof = file->tell(); - file->seek(0, SEEK_SET); - // Don't allow very long tokens here during recovery. All the interesting tokens are covered. - static size_t const MAX_LEN = 10; - while (file->tell() < eof) { - QPDFTokenizer::Token t1 = read_token(MAX_LEN); - qpdf_offset_t token_start = file->tell() - toO(t1.getValue().length()); - if (t1.isInteger()) { - auto pos = file->tell(); - QPDFTokenizer::Token t2 = read_token(MAX_LEN); - if (t2.isInteger() && read_token(MAX_LEN).isWord("obj")) { - int obj = QUtil::string_to_int(t1.getValue().c_str()); - int gen = QUtil::string_to_int(t2.getValue().c_str()); - if (obj <= max_id_) { - objects.emplace_back(obj, gen, token_start); - if (obj > max_found) { - max_found = obj; - } - } else { - warn_damaged("ignoring object with impossibly large id " + std::to_string(obj)); - } - } - file->seek(pos, SEEK_SET); - } else if (!trailer_ && t1.isWord("trailer")) { - trailers.emplace_back(file->tell()); - } - file->findAndSkipNextEOL(); - } - - table.resize(toS(max_found) + 1); - - for (auto tr: trailers) { - file->seek(tr, SEEK_SET); - auto t = read_trailer(); - if (!t.isDictionary()) { - // Oh well. It was worth a try. - } else { - trailer_ = t; - break; - } - check_warnings(); - } - - auto rend = objects.rend(); - for (auto it = objects.rbegin(); it != rend; it++) { - auto [obj, gen, token_start] = *it; - insert(obj, 1, token_start, gen); - check_warnings(); - } - - if (!trailer_) { - qpdf_offset_t max_offset{0}; - // If there are any xref streams, take the last one to appear. - int i = -1; - for (auto const& item: table) { - ++i; - if (item.type() != 1) { - continue; - } - auto oh = qpdf.getObject(i, item.gen()); - try { - if (!oh.isStreamOfType("/XRef")) { - continue; - } - } catch (std::exception&) { - continue; - } - auto offset = item.offset(); - if (offset > max_offset) { - max_offset = offset; - trailer_ = oh.getDict(); - } - check_warnings(); - } - if (max_offset > 0) { - try { - read(max_offset); - } catch (std::exception&) { - throw damaged_pdf( - "error decoding candidate xref stream while recovering damaged file"); - } - QTC::TC("qpdf", "QPDF recover xref stream"); - } - } - - if (!trailer_) { - // We could check the last encountered object to see if it was an xref stream. If so, we - // could try to get the trailer from there. This may make it possible to recover files with - // bad startxref pointers even when they have object streams. - - throw damaged_pdf("unable to find trailer dictionary while recovering damaged file"); - } - if (table.empty()) { - // We cannot check for an empty xref table in parse because empty tables are valid when - // creating QPDF objects from JSON. - throw damaged_pdf("unable to find objects while recovering damaged file"); - } - check_warnings(); - if (!initialized_) { - initialized_ = true; - qpdf.getAllPages(); - check_warnings(); - if (qpdf.m->all_pages.empty()) { - initialized_ = false; - throw damaged_pdf("unable to find any pages while recovering damaged file"); - } - } - // We could iterate through the objects looking for streams and try to find objects inside of - // them, but it's probably not worth the trouble. Acrobat can't recover files with any errors - // in an xref stream, and this would be a real long shot anyway. If we wanted to do anything - // that involved looking at stream contents, we'd also have to call initializeEncryption() here. - // It's safe to call it more than once. -} - -void -QPDF::Xref_table::read(qpdf_offset_t xref_offset) -{ - std::map free_table; - std::set visited; - while (xref_offset) { - visited.insert(xref_offset); - char buf[7]; - memset(buf, 0, sizeof(buf)); - file->seek(xref_offset, SEEK_SET); - // Some files miss the mark a little with startxref. We could do a better job of searching - // in the neighborhood for something that looks like either an xref table or stream, but the - // simple heuristic of skipping whitespace can help with the xref table case and is harmless - // with the stream case. - bool done = false; - bool skipped_space = false; - while (!done) { - char ch; - if (1 == file->read(&ch, 1)) { - if (QUtil::is_space(ch)) { - skipped_space = true; - } else { - file->unreadCh(ch); - done = true; - } - } else { - QTC::TC("qpdf", "QPDF eof skipping spaces before xref", skipped_space ? 0 : 1); - done = true; - } - } - - file->read(buf, sizeof(buf) - 1); - // The PDF spec says xref must be followed by a line terminator, but files exist in the wild - // where it is terminated by arbitrary whitespace. - if ((strncmp(buf, "xref", 4) == 0) && QUtil::is_space(buf[4])) { - if (skipped_space) { - QTC::TC("qpdf", "QPDF xref skipped space"); - warn_damaged("extraneous whitespace seen before xref"); - } - QTC::TC( - "qpdf", - "QPDF xref space", - ((buf[4] == '\n') ? 0 - : (buf[4] == '\r') ? 1 - : (buf[4] == ' ') ? 2 - : 9999)); - int skip = 4; - // buf is null-terminated, and QUtil::is_space('\0') is false, so this won't overrun. - while (QUtil::is_space(buf[skip])) { - ++skip; - } - xref_offset = process_section(xref_offset + skip); - } else { - xref_offset = read_stream(xref_offset); - } - if (visited.count(xref_offset) != 0) { - QTC::TC("qpdf", "QPDF xref loop"); - throw damaged_pdf("loop detected following xref tables"); - } - } - - if (!trailer_) { - throw damaged_pdf("unable to find trailer while reading xref"); - } - int size = trailer_.getKey("/Size").getIntValueAsInt(); - - if (size < 3) { - throw damaged_pdf("too few objects - file can't have a page tree"); - } - - // We are no longer reporting what the highest id in the xref table is. I don't think it adds - // anything. If we want to report more detail, we should report the total number of missing - // entries, including missing entries before the last actual entry. -} - -QPDF::Xref_table::Subsection -QPDF::Xref_table::subsection(std::string const& line) -{ - auto terminate = [this]() -> void { - QTC::TC("qpdf", "QPDF invalid xref"); - throw damaged_table("xref syntax invalid"); - }; - - // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated - // buffer. - char const* p = line.c_str(); - char const* start = line.c_str(); - - // Skip zero or more spaces - while (QUtil::is_space(*p)) { - ++p; - } - // Require digit - if (!QUtil::is_digit(*p)) { - terminate(); - } - // Gather digits - std::string obj_str; - while (QUtil::is_digit(*p)) { - obj_str.append(1, *p++); - } - // Require space - if (!QUtil::is_space(*p)) { - terminate(); - } - // Skip spaces - while (QUtil::is_space(*p)) { - ++p; - } - // Require digit - if (!QUtil::is_digit(*p)) { - terminate(); - } - // Gather digits - std::string num_str; - while (QUtil::is_digit(*p)) { - num_str.append(1, *p++); - } - // Skip any space including line terminators - while (QUtil::is_space(*p)) { - ++p; - } - auto obj = QUtil::string_to_int(obj_str.c_str()); - auto count = QUtil::string_to_int(num_str.c_str()); - if (obj > max_id() || count > max_id() || (obj + count) > max_id()) { - throw damaged_table("xref table subsection header contains impossibly large entry"); - } - return {obj, count, file->getLastOffset() + toI(p - start)}; -} - -std::vector -QPDF::Xref_table::bad_subsections(std::string& line, qpdf_offset_t start) -{ - std::vector result; - file->seek(start, SEEK_SET); - - while (true) { - line.assign(50, '\0'); - file->read(line.data(), line.size()); - auto [obj, num, offset] = result.emplace_back(subsection(line)); - file->seek(offset, SEEK_SET); - for (qpdf_offset_t i = obj; i - num < obj; ++i) { - if (!std::get<0>(read_entry())) { - QTC::TC("qpdf", "QPDF invalid xref entry"); - throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")"); - } - } - qpdf_offset_t pos = file->tell(); - if (read_token().isWord("trailer")) { - return result; - } else { - file->seek(pos, SEEK_SET); - } - } -} - -// Optimistically read and parse all subsection headers. If an error is encountered return the -// result of bad_subsections. -std::vector -QPDF::Xref_table::subsections(std::string& line) -{ - auto recovery_offset = file->tell(); - try { - std::vector result; - - while (true) { - line.assign(50, '\0'); - file->read(line.data(), line.size()); - auto& sub = result.emplace_back(subsection(line)); - auto count = std::get<1>(sub); - auto offset = std::get<2>(sub); - file->seek(offset + 20 * toO(count) - 1, SEEK_SET); - file->read(line.data(), 1); - if (!(line[0] == '\n' || line[0] == '\n')) { - return bad_subsections(line, recovery_offset); - } - qpdf_offset_t pos = file->tell(); - if (read_token().isWord("trailer")) { - return result; - } else { - file->seek(pos, SEEK_SET); - } - } - } catch (...) { - return bad_subsections(line, recovery_offset); - } -} - -// Returns (success, f1, f2, type). -std::tuple -QPDF::Xref_table::read_bad_entry() -{ - qpdf_offset_t f1{0}; - int f2{0}; - char type{'\0'}; - // Reposition after initial read attempt and reread. - file->seek(file->getLastOffset(), SEEK_SET); - auto line = file->readLine(30); - - // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated - // buffer. - char const* p = line.data(); - - // Skip zero or more spaces. There aren't supposed to be any. - bool invalid = false; - while (QUtil::is_space(*p)) { - ++p; - QTC::TC("qpdf", "QPDF ignore first space in xref entry"); - invalid = true; - } - // Require digit - if (!QUtil::is_digit(*p)) { - return {false, 0, 0, '\0'}; - } - // Gather digits - std::string f1_str; - while (QUtil::is_digit(*p)) { - f1_str.append(1, *p++); - } - // Require space - if (!QUtil::is_space(*p)) { - return {false, 0, 0, '\0'}; - } - if (QUtil::is_space(*(p + 1))) { - QTC::TC("qpdf", "QPDF ignore first extra space in xref entry"); - invalid = true; - } - // Skip spaces - while (QUtil::is_space(*p)) { - ++p; - } - // Require digit - if (!QUtil::is_digit(*p)) { - return {false, 0, 0, '\0'}; - } - // Gather digits - std::string f2_str; - while (QUtil::is_digit(*p)) { - f2_str.append(1, *p++); - } - // Require space - if (!QUtil::is_space(*p)) { - return {false, 0, 0, '\0'}; - } - if (QUtil::is_space(*(p + 1))) { - QTC::TC("qpdf", "QPDF ignore second extra space in xref entry"); - invalid = true; - } - // Skip spaces - while (QUtil::is_space(*p)) { - ++p; - } - if ((*p == 'f') || (*p == 'n')) { - type = *p; - } else { - return {false, 0, 0, '\0'}; - } - if ((f1_str.length() != 10) || (f2_str.length() != 5)) { - QTC::TC("qpdf", "QPDF ignore length error xref entry"); - invalid = true; - } - - if (invalid) { - qpdf.warn(damaged_table("accepting invalid xref table entry")); - } - - f1 = QUtil::string_to_ll(f1_str.c_str()); - f2 = QUtil::string_to_int(f2_str.c_str()); - - return {true, f1, f2, type}; -} - -// Optimistically read and parse xref entry. If entry is bad, call read_bad_xrefEntry and return -// result. Returns (success, f1, f2, type). -std::tuple -QPDF::Xref_table::read_entry() -{ - qpdf_offset_t f1{0}; - int f2{0}; - char type{'\0'}; - std::array line; - f1 = 0; - f2 = 0; - if (file->read(line.data(), 20) != 20) { - // C++20: [[unlikely]] - return {false, 0, 0, '\0'}; - } - line[20] = '\0'; - char const* p = line.data(); - - int f1_len = 0; - int f2_len = 0; - - // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated - // buffer. - - // Gather f1 digits. NB No risk of overflow as 9'999'999'999 < max long long. - while (*p == '0') { - ++f1_len; - ++p; - } - while (QUtil::is_digit(*p) && f1_len++ < 10) { - f1 *= 10; - f1 += *p++ - '0'; - } - // Require space - if (!QUtil::is_space(*p++)) { - // Entry doesn't start with space or digit. - // C++20: [[unlikely]] - return {false, 0, 0, '\0'}; - } - // Gather digits. NB No risk of overflow as 99'999 < max int. - while (*p == '0') { - ++f2_len; - ++p; - } - while (QUtil::is_digit(*p) && f2_len++ < 5) { - f2 *= 10; - f2 += static_cast(*p++ - '0'); - } - if (QUtil::is_space(*p++) && (*p == 'f' || *p == 'n')) { - // C++20: [[likely]] - type = *p; - // No test for valid line[19]. - if (*(++p) && *(++p) && (*p == '\n' || *p == '\r') && f1_len == 10 && f2_len == 5) { - // C++20: [[likely]] - return {true, f1, f2, type}; - } - } - return read_bad_entry(); -} - -// Read a single cross-reference table section and associated trailer. -qpdf_offset_t -QPDF::Xref_table::process_section(qpdf_offset_t xref_offset) -{ - file->seek(xref_offset, SEEK_SET); - std::string line; - auto subs = subsections(line); - - auto cur_trailer_offset = file->tell(); - auto cur_trailer = read_trailer(); - if (!cur_trailer.isDictionary()) { - QTC::TC("qpdf", "QPDF missing trailer"); - throw qpdf.damagedPDF("", "expected trailer dictionary"); - } - - if (!trailer_) { - unsigned int sz; - trailer_ = cur_trailer; - - if (!trailer_.hasKey("/Size")) { - QTC::TC("qpdf", "QPDF trailer lacks size"); - throw qpdf.damagedPDF("trailer", "trailer dictionary lacks /Size key"); - } - if (!trailer_.getKey("/Size").getValueAsUInt(sz)) { - QTC::TC("qpdf", "QPDF trailer size not integer"); - throw qpdf.damagedPDF("trailer", "/Size key in trailer dictionary is not an integer"); - } - if (sz >= static_cast(max_id_)) { - QTC::TC("qpdf", "QPDF trailer size impossibly large"); - throw qpdf.damagedPDF("trailer", "/Size key in trailer dictionary is impossibly large"); - } - table.resize(sz); - } - - for (auto [obj, num, offset]: subs) { - file->seek(offset, SEEK_SET); - for (qpdf_offset_t i = obj; i - num < obj; ++i) { - if (i == 0) { - // This is needed by checkLinearization() - first_item_offset_ = file->tell(); - } - // For xref_table, these will always be small enough to be ints - auto [success, f1, f2, type] = read_entry(); - if (!success) { - throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")"); - } - if (type == 'f') { - insert_free(QPDFObjGen(toI(i), f2)); - } else { - insert(toI(i), 1, f1, f2); - } - } - qpdf_offset_t pos = file->tell(); - if (read_token().isWord("trailer")) { - break; - } else { - file->seek(pos, SEEK_SET); - } - } - - if (cur_trailer.hasKey("/XRefStm")) { - if (ignore_streams_) { - QTC::TC("qpdf", "QPDF ignoring XRefStm in trailer"); - } else { - if (cur_trailer.getKey("/XRefStm").isInteger()) { - // Read the xref stream but disregard any return value -- we'll use our trailer's - // /Prev key instead of the xref stream's. - (void)read_stream(cur_trailer.getKey("/XRefStm").getIntValue()); - } else { - throw qpdf.damagedPDF("xref stream", cur_trailer_offset, "invalid /XRefStm"); - } - } - } - - if (cur_trailer.hasKey("/Prev")) { - if (!cur_trailer.getKey("/Prev").isInteger()) { - QTC::TC("qpdf", "QPDF trailer prev not integer"); - throw qpdf.damagedPDF( - "trailer", cur_trailer_offset, "/Prev key in trailer dictionary is not an integer"); - } - QTC::TC("qpdf", "QPDF prev key in trailer dictionary"); - return cur_trailer.getKey("/Prev").getIntValue(); - } - - return 0; -} - -// Read a single cross-reference stream. -qpdf_offset_t -QPDF::Xref_table::read_stream(qpdf_offset_t xref_offset) -{ - if (!ignore_streams_) { - QPDFObjGen x_og; - QPDFObjectHandle xref_obj; - try { - xref_obj = qpdf.readObjectAtOffset( - false, xref_offset, "xref stream", QPDFObjGen(0, 0), x_og, true); - } catch (QPDFExc&) { - // ignore -- report error below - } - if (xref_obj.isStreamOfType("/XRef")) { - QTC::TC("qpdf", "QPDF found xref stream"); - return process_stream(xref_offset, xref_obj); - } - } - - QTC::TC("qpdf", "QPDF can't find xref"); - throw qpdf.damagedPDF("", xref_offset, "xref not found"); - return 0; // unreachable -} - -// Return the entry size of the xref stream and the processed W array. -std::pair> -QPDF::Xref_table::process_W( - QPDFObjectHandle& dict, std::function damaged) -{ - auto W_obj = dict.getKey("/W"); - if (!(W_obj.isArray() && W_obj.getArrayNItems() >= 3 && W_obj.getArrayItem(0).isInteger() && - W_obj.getArrayItem(1).isInteger() && W_obj.getArrayItem(2).isInteger())) { - throw damaged("Cross-reference stream does not have a proper /W key"); - } - - std::array W; - int entry_size = 0; - auto w_vector = W_obj.getArrayAsVector(); - int max_bytes = sizeof(qpdf_offset_t); - for (size_t i = 0; i < 3; ++i) { - W[i] = w_vector[i].getIntValueAsInt(); - if (W[i] > max_bytes) { - throw damaged("Cross-reference stream's /W contains impossibly large values"); - } - if (W[i] < 0) { - throw damaged("Cross-reference stream's /W contains negative values"); - } - entry_size += W[i]; - } - if (entry_size == 0) { - throw damaged("Cross-reference stream's /W indicates entry size of 0"); - } - return {entry_size, W}; -} - -// Validate Size entry and return the maximum number of entries that the xref stream can contain and -// the value of the Size entry. -std::pair -QPDF::Xref_table::process_Size( - QPDFObjectHandle& dict, int entry_size, std::function damaged) -{ - // Number of entries is limited by the highest possible object id and stream size. - auto max_num_entries = std::numeric_limits::max(); - if (max_num_entries > (std::numeric_limits::max() / entry_size)) { - max_num_entries = toI(std::numeric_limits::max() / entry_size); - } - - auto Size_obj = dict.getKey("/Size"); - long long size; - if (!dict.getKey("/Size").getValueAsInt(size)) { - throw damaged("Cross-reference stream does not have a proper /Size key"); - } else if (size < 0) { - throw damaged("Cross-reference stream has a negative /Size key"); - } else if (size >= max_num_entries) { - throw damaged("Cross-reference stream has an impossibly large /Size key"); - } - // We are not validating that Size <= (Size key of parent xref / trailer). - return {max_num_entries, toS(size)}; -} - -// Return the number of entries of the xref stream and the processed Index array. -std::pair>> -QPDF::Xref_table::process_Index( - QPDFObjectHandle& dict, int max_num_entries, std::function damaged) -{ - auto size = dict.getKey("/Size").getIntValueAsInt(); - auto Index_obj = dict.getKey("/Index"); - - if (Index_obj.isArray()) { - std::vector> indx; - int num_entries = 0; - auto index_vec = Index_obj.getArrayAsVector(); - if ((index_vec.size() % 2) || index_vec.size() < 2) { - throw damaged("Cross-reference stream's /Index has an invalid number of values"); - } - - int i = 0; - long long first = 0; - for (auto& val: index_vec) { - if (val.isInteger()) { - if (i % 2) { - auto count = val.getIntValue(); - if (count <= 0) { - throw damaged( - "Cross-reference stream section claims to contain " + - std::to_string(count) + " entries"); - } - // We are guarding against the possibility of num_entries * entry_size - // overflowing. We are not checking that entries are in ascending order as - // required by the spec, which probably should generate a warning. We are also - // not checking that for each subsection first object number + number of entries - // <= /Size. The spec requires us to ignore object number > /Size. - if (first > (max_num_entries - count) || - count > (max_num_entries - num_entries)) { - throw damaged( - "Cross-reference stream claims to contain too many entries: " + - std::to_string(first) + " " + std::to_string(max_num_entries) + " " + - std::to_string(num_entries)); - } - indx.emplace_back(static_cast(first), static_cast(count)); - num_entries += static_cast(count); - } else { - first = val.getIntValue(); - if (first < 0) { - throw damaged( - "Cross-reference stream's /Index contains a negative object id"); - } else if (first > max_num_entries) { - throw damaged("Cross-reference stream's /Index contains an impossibly " - "large object id"); - } - } - } else { - throw damaged( - "Cross-reference stream's /Index's item " + std::to_string(i) + - " is not an integer"); - } - i++; - } - QTC::TC("qpdf", "QPDF xref /Index is array", index_vec.size() == 2 ? 0 : 1); - return {num_entries, indx}; - } else if (Index_obj.isNull()) { - QTC::TC("qpdf", "QPDF xref /Index is null"); - return {size, {{0, size}}}; - } else { - throw damaged("Cross-reference stream does not have a proper /Index key"); - } -} - -qpdf_offset_t -QPDF::Xref_table::process_stream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj) -{ - auto damaged = [this, xref_offset](std::string_view msg) -> QPDFExc { - return qpdf.damagedPDF("xref stream", xref_offset, msg.data()); - }; - - auto dict = xref_obj.getDict(); - - auto [entry_size, W] = process_W(dict, damaged); - auto [max_num_entries, size] = process_Size(dict, entry_size, damaged); - auto [num_entries, indx] = process_Index(dict, max_num_entries, damaged); - - std::shared_ptr bp = xref_obj.getStreamData(qpdf_dl_specialized); - size_t actual_size = bp->getSize(); - auto expected_size = toS(entry_size) * toS(num_entries); - - if (expected_size != actual_size) { - QPDFExc x = damaged( - "Cross-reference stream data has the wrong size; expected = " + - std::to_string(expected_size) + "; actual = " + std::to_string(actual_size)); - if (expected_size > actual_size) { - throw x; - } else { - qpdf.warn(x); - } - } - - if (!trailer_) { - trailer_ = dict; - if (size > toS(max_id_)) { - throw damaged("Cross-reference stream /Size entry is impossibly large"); - } - table.resize(size); - } - - bool saw_first_compressed_object = false; - - // Actual size vs. expected size check above ensures that we will not overflow any buffers here. - // We know that entry_size * num_entries is less or equal to the size of the buffer. - auto p = bp->getBuffer(); - for (auto [obj, sec_entries]: indx) { - // Process a subsection. - for (int i = 0; i < sec_entries; ++i) { - // Read this entry - std::array fields{}; - if (W[0] == 0) { - QTC::TC("qpdf", "QPDF default for xref stream field 0"); - fields[0] = 1; - } - for (size_t j = 0; j < 3; ++j) { - for (int k = 0; k < W[j]; ++k) { - fields[j] <<= 8; - fields[j] |= *p++; - } - } - - // Get the generation number. The generation number is 0 unless this is an uncompressed - // object record, in which case the generation number appears as the third field. - if (saw_first_compressed_object) { - if (fields[0] != 2) { - uncompressed_after_compressed_ = true; - } - } else if (fields[0] == 2) { - saw_first_compressed_object = true; - } - if (obj == 0) { - // This is needed by checkLinearization() - first_item_offset_ = xref_offset; - } else if (fields[0] == 0) { - // Ignore fields[2], which we don't care about in this case. This works around the - // issue of some PDF files that put invalid values, like -1, here for deleted - // objects. - insert_free(QPDFObjGen(obj, 0)); - } else { - insert(obj, toI(fields[0]), fields[1], toI(fields[2])); - } - ++obj; - } - } - - if (dict.hasKey("/Prev")) { - if (!dict.getKey("/Prev").isInteger()) { - throw qpdf.damagedPDF( - "xref stream", "/Prev key in xref stream dictionary is not an integer"); - } - QTC::TC("qpdf", "QPDF prev key in xref stream dictionary"); - return dict.getKey("/Prev").getIntValue(); - } else { - return 0; - } -} - -void -QPDF::Xref_table::insert(int obj, int f0, qpdf_offset_t f1, int f2) -{ - // Populate the xref table in such a way that the first reference to an object that we see, - // which is the one in the latest xref table in which it appears, is the one that gets stored. - // This works because we are reading more recent appends before older ones. - - // If there is already an entry for this object and generation in the table, it means that a - // later xref table has registered this object. Disregard this one. - - int new_gen = f0 == 2 ? 0 : f2; - - if (!(obj > 0 && static_cast(obj) < table.size() && 0 <= f2 && new_gen < 65535)) { - // We are ignoring invalid objgens. Most will arrive here from xref reconstruction. There - // is probably no point having another warning but we could count invalid items in order to - // decide when to give up. - QTC::TC("qpdf", "QPDF xref overwrite invalid objgen"); - return; - } - - auto& entry = table[static_cast(obj)]; - auto old_type = entry.type(); - - if (!old_type && entry.gen() > 0) { - // At the moment we are processing the updates last to first and therefore the gen doesn't - // matter as long as it > 0 to distinguish it from an uninitialized entry. This will need - // to be revisited when we want to support incremental updates or more comprhensive - // checking. - QTC::TC("qpdf", "QPDF xref deleted object"); - return; - } - - if (f0 == 2 && static_cast(f1) == obj) { - qpdf.warn(qpdf.damagedPDF( - "xref stream", "self-referential object stream " + std::to_string(obj))); - return; - } - - if (old_type && entry.gen() >= new_gen) { - QTC::TC("qpdf", "QPDF xref reused object"); - return; - } - - switch (f0) { - case 1: - // f2 is generation - QTC::TC("qpdf", "QPDF xref gen > 0", (f2 > 0) ? 1 : 0); - entry = {f2, Uncompressed(f1)}; - break; - - case 2: - entry = {0, Compressed(toI(f1), f2)}; - object_streams_ = true; - break; - - default: - throw qpdf.damagedPDF( - "xref stream", "unknown xref stream entry type " + std::to_string(f0)); - break; - } -} - -void -QPDF::Xref_table::insert_free(QPDFObjGen og) -{ - // At the moment we are processing the updates last to first and therefore the gen doesn't - // matter as long as it > 0 to distinguish it from an uninitialized entry. This will need to be - // revisited when we want to support incremental updates or more comprhensive checking. - if (og.getObj() < 1) { - return; - } - size_t id = static_cast(og.getObj()); - if (id < table.size() && !type(id)) { - table[id] = {1, {}}; - } -} - -QPDFObjGen -QPDF::Xref_table::at_offset(qpdf_offset_t offset) const noexcept -{ - int id = 0; - int gen = 0; - qpdf_offset_t start = 0; - - int i = 0; - for (auto const& item: table) { - auto o = item.offset(); - if (start < o && o <= offset) { - start = o; - id = i; - gen = item.gen(); - } - ++i; - } - return QPDFObjGen(id, gen); -} - -std::map -QPDF::Xref_table::as_map() const -{ - std::map result; - int i{0}; - for (auto const& item: table) { - switch (item.type()) { - case 0: - break; - case 1: - result.emplace(QPDFObjGen(i, item.gen()), item.offset()); - break; - case 2: - result.emplace( - QPDFObjGen(i, 0), QPDFXRefEntry(item.stream_number(), item.stream_index())); - break; - default: - throw std::logic_error("Xref_table: invalid entry type"); - } - ++i; - } - return result; -} - void QPDF::showXRefTable() { - m->xref_table.show(); -} - -void -QPDF::Xref_table::show() -{ - auto& cout = *qpdf.m->log->getInfo(); - int i = -1; - for (auto const& item: table) { - ++i; - if (item.type()) { - cout << std::to_string(i) << "/" << std::to_string(item.gen()) << ": "; - switch (item.type()) { - case 1: - cout << "uncompressed; offset = " << item.offset() << "\n"; - break; - - case 2: - cout << "compressed; stream = " << item.stream_number() - << ", index = " << item.stream_index() << "\n"; - break; - - default: - throw std::logic_error( - "unknown cross-reference table type while showing xref_table"); - } - } - } -} - -// Resolve all objects in the xref table. If this triggers a xref table reconstruction abort and -// return false. Otherwise return true. -bool -QPDF::Xref_table::resolve() -{ - bool may_change = !reconstructed_; - int i = -1; - for (auto& item: table) { - ++i; - if (item.type()) { - if (qpdf.isUnresolved(QPDFObjGen(i, item.gen()))) { - qpdf.resolve(QPDFObjGen(i, item.gen())); - if (may_change && reconstructed_) { - return false; - } - } - } - } - return true; + m->objects.xref_table().show(); } // Ensure all objects in the pdf file, including those in indirect references, appear in the object @@ -1541,9 +461,9 @@ QPDF::fixDanglingReferences(bool force) if (m->fixed_dangling_refs) { return; } - if (!m->xref_table.resolve()) { + if (!m->objects.xref_table().resolve()) { QTC::TC("qpdf", "QPDF fix dangling triggered xref reconstruction"); - m->xref_table.resolve(); + m->objects.xref_table().resolve(); } m->fixed_dangling_refs = true; } @@ -1554,24 +474,13 @@ QPDF::getObjectCount() // This method returns the next available indirect object number. makeIndirectObject uses it for // this purpose. After fixDanglingReferences is called, all objects in the xref table will also // be in obj_cache. - fixDanglingReferences(); - QPDFObjGen og; - if (!m->obj_cache.empty()) { - og = (*(m->obj_cache.rbegin())).first; - } - return toS(og.getObj()); + return toS(m->objects.next_id().getObj() - 1); } std::vector QPDF::getAllObjects() { - // After fixDanglingReferences is called, all objects are in the object cache. - fixDanglingReferences(); - std::vector result; - for (auto const& iter: m->obj_cache) { - result.push_back(newIndirect(iter.first, iter.second.object)); - } - return result; + return m->objects.all(); } void @@ -1589,539 +498,12 @@ QPDF::setLastObjectDescription(std::string const& description, QPDFObjGen const& } } -QPDFObjectHandle -QPDF::Xref_table::read_trailer() -{ - qpdf_offset_t offset = file->tell(); - bool empty = false; - auto object = QPDFParser(*file, "trailer", tokenizer, nullptr, &qpdf, true).parse(empty, false); - if (empty) { - // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in - // actual PDF files and Adobe Reader appears to ignore them. - qpdf.warn(qpdf.damagedPDF("trailer", "empty object treated as null")); - } else if (object.isDictionary() && read_token().isWord("stream")) { - qpdf.warn(qpdf.damagedPDF("trailer", file->tell(), "stream keyword found in trailer")); - } - // Override last_offset so that it points to the beginning of the object we just read - file->setLastOffset(offset); - return object; -} - -QPDFObjectHandle -QPDF::readObject(std::string const& description, QPDFObjGen og) -{ - setLastObjectDescription(description, og); - qpdf_offset_t offset = m->file->tell(); - bool empty = false; - - StringDecrypter decrypter{this, og}; - StringDecrypter* decrypter_ptr = m->encp->encrypted ? &decrypter : nullptr; - auto object = - QPDFParser(*m->file, m->last_object_description, m->tokenizer, decrypter_ptr, this, true) - .parse(empty, false); - if (empty) { - // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in - // actual PDF files and Adobe Reader appears to ignore them. - warn(damagedPDF(*m->file, m->file->getLastOffset(), "empty object treated as null")); - return object; - } - auto token = readToken(*m->file); - if (object.isDictionary() && token.isWord("stream")) { - readStream(object, og, offset); - token = readToken(*m->file); - } - if (!token.isWord("endobj")) { - QTC::TC("qpdf", "QPDF err expected endobj"); - warn(damagedPDF("expected endobj")); - } - return object; -} - -// After reading stream dictionary and stream keyword, read rest of stream. -void -QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset) -{ - validateStreamLineEnd(object, og, offset); - - // Must get offset before accessing any additional objects since resolving a previously - // unresolved indirect object will change file position. - qpdf_offset_t stream_offset = m->file->tell(); - size_t length = 0; - - try { - auto length_obj = object.getKey("/Length"); - - if (!length_obj.isInteger()) { - if (length_obj.isNull()) { - QTC::TC("qpdf", "QPDF stream without length"); - throw damagedPDF(offset, "stream dictionary lacks /Length key"); - } - QTC::TC("qpdf", "QPDF stream length not integer"); - throw damagedPDF(offset, "/Length key in stream dictionary is not an integer"); - } - - length = toS(length_obj.getUIntValue()); - // Seek in two steps to avoid potential integer overflow - m->file->seek(stream_offset, SEEK_SET); - m->file->seek(toO(length), SEEK_CUR); - if (!readToken(*m->file).isWord("endstream")) { - QTC::TC("qpdf", "QPDF missing endstream"); - throw damagedPDF("expected endstream"); - } - } catch (QPDFExc& e) { - if (m->attempt_recovery) { - warn(e); - length = recoverStreamLength(m->file_sp, og, stream_offset); - } else { - throw; - } - } - object = {QPDF_Stream::create(this, og, object, stream_offset, length)}; -} - -void -QPDF::validateStreamLineEnd(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset) -{ - // The PDF specification states that the word "stream" should be followed by either a carriage - // return and a newline or by a newline alone. It specifically disallowed following it by a - // carriage return alone since, in that case, there would be no way to tell whether the NL in a - // CR NL sequence was part of the stream data. However, some readers, including Adobe reader, - // accept a carriage return by itself when followed by a non-newline character, so that's what - // we do here. We have also seen files that have extraneous whitespace between the stream - // keyword and the newline. - while (true) { - char ch; - if (m->file->read(&ch, 1) == 0) { - // A premature EOF here will result in some other problem that will get reported at - // another time. - return; - } - if (ch == '\n') { - // ready to read stream data - QTC::TC("qpdf", "QPDF stream with NL only"); - return; - } - if (ch == '\r') { - // Read another character - if (m->file->read(&ch, 1) != 0) { - if (ch == '\n') { - // Ready to read stream data - QTC::TC("qpdf", "QPDF stream with CRNL"); - } else { - // Treat the \r by itself as the whitespace after endstream and start reading - // stream data in spite of not having seen a newline. - QTC::TC("qpdf", "QPDF stream with CR only"); - m->file->unreadCh(ch); - warn(damagedPDF( - m->file->tell(), "stream keyword followed by carriage return only")); - } - } - return; - } - if (!QUtil::is_space(ch)) { - QTC::TC("qpdf", "QPDF stream without newline"); - m->file->unreadCh(ch); - warn(damagedPDF( - m->file->tell(), "stream keyword not followed by proper line terminator")); - return; - } - warn(damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace")); - } -} - -QPDFObjectHandle -QPDF::readObjectInStream(std::shared_ptr& input, int obj) -{ - m->last_object_description.erase(7); // last_object_description starts with "object " - m->last_object_description += std::to_string(obj); - m->last_object_description += " 0"; - - bool empty = false; - auto object = QPDFParser(*input, m->last_object_description, m->tokenizer, nullptr, this, true) - .parse(empty, false); - if (empty) { - // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in - // actual PDF files and Adobe Reader appears to ignore them. - warn(damagedPDF(*input, input->getLastOffset(), "empty object treated as null")); - } - return object; -} - -bool -QPDF::findEndstream() -{ - // Find endstream or endobj. Position the input at that token. - auto t = readToken(*m->file, 20); - if (t.isWord("endobj") || t.isWord("endstream")) { - m->file->seek(m->file->getLastOffset(), SEEK_SET); - return true; - } - return false; -} - -size_t -QPDF::recoverStreamLength( - std::shared_ptr input, QPDFObjGen const& og, qpdf_offset_t stream_offset) -{ - // Try to reconstruct stream length by looking for endstream or endobj - warn(damagedPDF(*input, stream_offset, "attempting to recover stream length")); - - PatternFinder ef(*this, &QPDF::findEndstream); - size_t length = 0; - if (m->file->findFirst("end", stream_offset, 0, ef)) { - length = toS(m->file->tell() - stream_offset); - // Reread endstream but, if it was endobj, don't skip that. - QPDFTokenizer::Token t = readToken(*m->file); - if (t.getValue() == "endobj") { - m->file->seek(m->file->getLastOffset(), SEEK_SET); - } - } - - if (length) { - // Make sure this is inside this object - auto found = m->xref_table.at_offset(stream_offset + toO(length)); - if (found == QPDFObjGen() || found == og) { - // If we are trying to recover an XRef stream the xref table will not contain and - // won't contain any entries, therefore we cannot check the found length. Otherwise we - // found endstream\nendobj within the space allowed for this object, so we're probably - // in good shape. - } else { - QTC::TC("qpdf", "QPDF found wrong endstream in recovery"); - length = 0; - } - } - - if (length == 0) { - warn(damagedPDF( - *input, stream_offset, "unable to recover stream data; treating stream as empty")); - } else { - warn(damagedPDF( - *input, stream_offset, "recovered stream length: " + std::to_string(length))); - } - - QTC::TC("qpdf", "QPDF recovered stream length"); - return length; -} - QPDFTokenizer::Token QPDF::readToken(InputSource& input, size_t max_len) { return m->tokenizer.readToken(input, m->last_object_description, true, max_len); } -QPDFObjectHandle -QPDF::readObjectAtOffset( - bool try_recovery, - qpdf_offset_t offset, - std::string const& description, - QPDFObjGen exp_og, - QPDFObjGen& og, - bool skip_cache_if_in_xref) -{ - bool check_og = true; - if (exp_og.getObj() == 0) { - // This method uses an expect object ID of 0 to indicate that we don't know or don't care - // what the actual object ID is at this offset. This is true when we read the xref stream - // and linearization hint streams. In this case, we don't verify the expect object - // ID/generation against what was read from the file. There is also no reason to attempt - // xref recovery if we get a failure in this case since the read attempt was not triggered - // by an xref lookup. - check_og = false; - try_recovery = false; - } - setLastObjectDescription(description, exp_og); - - if (!m->attempt_recovery) { - try_recovery = false; - } - - // Special case: if offset is 0, just return null. Some PDF writers, in particular - // "Mac OS X 10.7.5 Quartz PDFContext", may store deleted objects in the xref table as - // "0000000000 00000 n", which is not correct, but it won't hurt anything for us to ignore - // these. - if (offset == 0) { - QTC::TC("qpdf", "QPDF bogus 0 offset", 0); - warn(damagedPDF(0, "object has offset 0")); - return QPDFObjectHandle::newNull(); - } - - m->file->seek(offset, SEEK_SET); - try { - QPDFTokenizer::Token tobjid = readToken(*m->file); - bool objidok = tobjid.isInteger(); - QTC::TC("qpdf", "QPDF check objid", objidok ? 1 : 0); - if (!objidok) { - QTC::TC("qpdf", "QPDF expected n n obj"); - throw damagedPDF(offset, "expected n n obj"); - } - QPDFTokenizer::Token tgen = readToken(*m->file); - bool genok = tgen.isInteger(); - QTC::TC("qpdf", "QPDF check generation", genok ? 1 : 0); - if (!genok) { - throw damagedPDF(offset, "expected n n obj"); - } - QPDFTokenizer::Token tobj = readToken(*m->file); - - bool objok = tobj.isWord("obj"); - QTC::TC("qpdf", "QPDF check obj", objok ? 1 : 0); - - if (!objok) { - throw damagedPDF(offset, "expected n n obj"); - } - int objid = QUtil::string_to_int(tobjid.getValue().c_str()); - int generation = QUtil::string_to_int(tgen.getValue().c_str()); - og = QPDFObjGen(objid, generation); - if (objid == 0) { - QTC::TC("qpdf", "QPDF object id 0"); - throw damagedPDF(offset, "object with ID 0"); - } - if (check_og && (exp_og != og)) { - QTC::TC("qpdf", "QPDF err wrong objid/generation"); - QPDFExc e = damagedPDF(offset, "expected " + exp_og.unparse(' ') + " obj"); - if (try_recovery) { - // Will be retried below - throw e; - } else { - // We can try reading the object anyway even if the ID doesn't match. - warn(e); - } - } - } catch (QPDFExc& e) { - if (try_recovery) { - // Try again after reconstructing xref table - m->xref_table.reconstruct(e); - if (m->xref_table.type(exp_og) == 1) { - QTC::TC("qpdf", "QPDF recovered in readObjectAtOffset"); - return readObjectAtOffset( - false, m->xref_table.offset(exp_og), description, exp_og, og, false); - } else { - QTC::TC("qpdf", "QPDF object gone after xref reconstruction"); - warn(damagedPDF( - "", - 0, - ("object " + exp_og.unparse(' ') + - " not found in file after regenerating cross reference table"))); - return QPDFObjectHandle::newNull(); - } - } else { - throw; - } - } - - QPDFObjectHandle oh = readObject(description, og); - - if (isUnresolved(og)) { - // Store the object in the cache here so it gets cached whether we first know the offset or - // whether we first know the object ID and generation (in which we case we would get here - // through resolve). - - // Determine the end offset of this object before and after white space. We use these - // numbers to validate linearization hint tables. Offsets and lengths of objects may imply - // the end of an object to be anywhere between these values. - qpdf_offset_t end_before_space = m->file->tell(); - - // skip over spaces - while (true) { - char ch; - if (m->file->read(&ch, 1)) { - if (!isspace(static_cast(ch))) { - m->file->seek(-1, SEEK_CUR); - break; - } - } else { - throw damagedPDF(m->file->tell(), "EOF after endobj"); - } - } - qpdf_offset_t end_after_space = m->file->tell(); - if (skip_cache_if_in_xref && m->xref_table.type(og)) { - // Ordinarily, an object gets read here when resolved through xref table or stream. In - // the special case of the xref stream and linearization hint tables, the offset comes - // from another source. For the specific case of xref streams, the xref stream is read - // and loaded into the object cache very early in parsing. Ordinarily, when a file is - // updated by appending, items inserted into the xref table in later updates take - // precedence over earlier items. In the special case of reusing the object number - // previously used as the xref stream, we have the following order of events: - // - // * reused object gets loaded into the xref table - // * old object is read here while reading xref streams - // * original xref entry is ignored (since already in xref table) - // - // It is the second step that causes a problem. Even though the xref table is correct in - // this case, the old object is already in the cache and so effectively prevails over - // the reused object. To work around this issue, we have a special case for the xref - // stream (via the skip_cache_if_in_xref): if the object is already in the xref stream, - // don't cache what we read here. - // - // It is likely that the same bug may exist for linearization hint tables, but the - // existing code uses end_before_space and end_after_space from the cache, so fixing - // that would require more significant rework. The chances of a linearization hint - // stream being reused seems smaller because the xref stream is probably the highest - // object in the file and the linearization hint stream would be some random place in - // the middle, so I'm leaving that bug unfixed for now. If the bug were to be fixed, we - // could use !check_og in place of skip_cache_if_in_xref. - QTC::TC("qpdf", "QPDF skipping cache for known unchecked object"); - } else { - m->xref_table.linearization_offsets( - toS(og.getObj()), end_before_space, end_after_space); - updateCache(og, oh.getObj()); - } - } - - return oh; -} - -QPDFObject* -QPDF::resolve(QPDFObjGen og) -{ - if (!isUnresolved(og)) { - return m->obj_cache[og].object.get(); - } - - if (m->resolving.count(og)) { - // This can happen if an object references itself directly or indirectly in some key that - // has to be resolved during object parsing, such as stream length. - QTC::TC("qpdf", "QPDF recursion loop in resolve"); - warn(damagedPDF("", "loop detected resolving object " + og.unparse(' '))); - updateCache(og, QPDF_Null::create()); - return m->obj_cache[og].object.get(); - } - ResolveRecorder rr(this, og); - - try { - switch (m->xref_table.type(og)) { - case 0: - break; - case 1: - { - // Object stored in cache by readObjectAtOffset - QPDFObjGen a_og; - QPDFObjectHandle oh = - readObjectAtOffset(true, m->xref_table.offset(og), "", og, a_og, false); - } - break; - - case 2: - resolveObjectsInStream(m->xref_table.stream_number(og.getObj())); - break; - - default: - throw damagedPDF( - "", 0, ("object " + og.unparse('/') + " has unexpected xref entry type")); - } - } catch (QPDFExc& e) { - warn(e); - } catch (std::exception& e) { - warn(damagedPDF( - "", 0, ("object " + og.unparse('/') + ": error reading object: " + e.what()))); - } - - if (isUnresolved(og)) { - // PDF spec says unknown objects resolve to the null object. - QTC::TC("qpdf", "QPDF resolve failure to null"); - updateCache(og, QPDF_Null::create()); - } - - auto result(m->obj_cache[og].object); - result->setDefaultDescription(this, og); - return result.get(); -} - -void -QPDF::resolveObjectsInStream(int obj_stream_number) -{ - if (m->resolved_object_streams.count(obj_stream_number)) { - return; - } - m->resolved_object_streams.insert(obj_stream_number); - // Force resolution of object stream - QPDFObjectHandle obj_stream = getObjectByID(obj_stream_number, 0); - if (!obj_stream.isStream()) { - throw damagedPDF( - "supposed object stream " + std::to_string(obj_stream_number) + " is not a stream"); - } - - QPDFObjectHandle dict = obj_stream.getDict(); - if (!dict.isDictionaryOfType("/ObjStm")) { - QTC::TC("qpdf", "QPDF ERR object stream with wrong type"); - warn(damagedPDF( - "supposed object stream " + std::to_string(obj_stream_number) + " has wrong type")); - } - - if (!(dict.getKey("/N").isInteger() && dict.getKey("/First").isInteger())) { - throw damagedPDF( - ("object stream " + std::to_string(obj_stream_number) + " has incorrect keys")); - } - - int n = dict.getKey("/N").getIntValueAsInt(); - int first = dict.getKey("/First").getIntValueAsInt(); - - std::map offsets; - - std::shared_ptr bp = obj_stream.getStreamData(qpdf_dl_specialized); - auto input = std::shared_ptr( - // line-break - new BufferInputSource( - (m->file->getName() + " object stream " + std::to_string(obj_stream_number)), - bp.get())); - - qpdf_offset_t last_offset = -1; - for (int i = 0; i < n; ++i) { - QPDFTokenizer::Token tnum = readToken(*input); - QPDFTokenizer::Token toffset = readToken(*input); - if (!(tnum.isInteger() && toffset.isInteger())) { - throw damagedPDF( - *input, - m->last_object_description, - input->getLastOffset(), - "expected integer in object stream header"); - } - - int num = QUtil::string_to_int(tnum.getValue().c_str()); - long long offset = QUtil::string_to_int(toffset.getValue().c_str()); - if (num > m->xref_table.max_id()) { - continue; - } - if (num == obj_stream_number) { - QTC::TC("qpdf", "QPDF ignore self-referential object stream"); - warn(damagedPDF( - *input, - m->last_object_description, - input->getLastOffset(), - "object stream claims to contain itself")); - continue; - } - if (offset <= last_offset) { - throw damagedPDF( - *input, - m->last_object_description, - input->getLastOffset(), - "expected offsets in object stream to be increasing"); - } - last_offset = offset; - - offsets[num] = toI(offset + first); - } - - // To avoid having to read the object stream multiple times, store all objects that would be - // found here in the cache. Remember that some objects stored here might have been overridden - // by new objects appended to the file, so it is necessary to recheck the xref table and only - // cache what would actually be resolved here. - m->last_object_description.clear(); - m->last_object_description += "object "; - for (auto const& iter: offsets) { - QPDFObjGen og(iter.first, 0); - if (m->xref_table.type(og) == 2 && - m->xref_table.stream_number(og.getObj()) == obj_stream_number) { - int offset = iter.second; - input->seek(offset, SEEK_SET); - QPDFObjectHandle oh = readObjectInStream(input, iter.first); - updateCache(og, oh.getObj()); - } else { - QTC::TC("qpdf", "QPDF not caching overridden objstm object"); - } - } -} - QPDFObjectHandle QPDF::newIndirect(QPDFObjGen const& og, std::shared_ptr const& obj) { @@ -2129,74 +511,32 @@ QPDF::newIndirect(QPDFObjGen const& og, std::shared_ptr const& obj) return {obj}; } -void -QPDF::updateCache(QPDFObjGen const& og, std::shared_ptr const& object) -{ - object->setObjGen(this, og); - if (isCached(og)) { - auto& cache = m->obj_cache[og]; - cache.object->assign(object); - } else { - m->obj_cache[og] = ObjCache(object); - } -} - -bool -QPDF::isCached(QPDFObjGen const& og) -{ - return m->obj_cache.count(og) != 0; -} - -bool -QPDF::isUnresolved(QPDFObjGen const& og) -{ - return !isCached(og) || m->obj_cache[og].object->isUnresolved(); -} - -QPDFObjGen -QPDF::nextObjGen() -{ - int max_objid = toI(getObjectCount()); - if (max_objid == std::numeric_limits::max()) { - throw std::range_error("max object id is too high to create new objects"); - } - return QPDFObjGen(max_objid + 1, 0); -} - -QPDFObjectHandle -QPDF::makeIndirectFromQPDFObject(std::shared_ptr const& obj) -{ - QPDFObjGen next{nextObjGen()}; - m->obj_cache[next] = ObjCache(obj); - return newIndirect(next, m->obj_cache[next].object); -} - QPDFObjectHandle QPDF::makeIndirectObject(QPDFObjectHandle oh) { if (!oh) { throw std::logic_error("attempted to make an uninitialized QPDFObjectHandle indirect"); } - return makeIndirectFromQPDFObject(oh.getObj()); + return m->objects.make_indirect(oh.getObj()); } QPDFObjectHandle QPDF::newReserved() { - return makeIndirectFromQPDFObject(QPDF_Reserved::create()); + return m->objects.make_indirect(QPDF_Reserved::create()); } QPDFObjectHandle QPDF::newIndirectNull() { - return makeIndirectFromQPDFObject(QPDF_Null::create()); + return m->objects.make_indirect(QPDF_Null::create()); } QPDFObjectHandle QPDF::newStream() { - return makeIndirectFromQPDFObject( - QPDF_Stream::create(this, nextObjGen(), QPDFObjectHandle::newDictionary(), 0, 0)); + return m->objects.make_indirect( + QPDF_Stream::create(this, m->objects.next_id(), QPDFObjectHandle::newDictionary(), 0, 0)); } QPDFObjectHandle @@ -2215,93 +555,40 @@ QPDF::newStream(std::string const& data) return result; } -std::shared_ptr -QPDF::getObjectForParser(int id, int gen, bool parse_pdf) -{ - // This method is called by the parser and therefore must not resolve any objects. - auto og = QPDFObjGen(id, gen); - if (auto iter = m->obj_cache.find(og); iter != m->obj_cache.end()) { - return iter->second.object; - } - if (m->xref_table.type(og) || !m->xref_table.initialized()) { - return m->obj_cache.insert({og, QPDF_Unresolved::create(this, og)}).first->second.object; - } - if (parse_pdf) { - return QPDF_Null::create(); - } - return m->obj_cache.insert({og, QPDF_Null::create(this, og)}).first->second.object; -} - -std::shared_ptr -QPDF::getObjectForJSON(int id, int gen) -{ - auto og = QPDFObjGen(id, gen); - auto [it, inserted] = m->obj_cache.try_emplace(og); - auto& obj = it->second.object; - if (inserted) { - obj = (m->xref_table.initialized() && !m->xref_table.type(og)) - ? QPDF_Null::create(this, og) - : QPDF_Unresolved::create(this, og); - } - return obj; -} - QPDFObjectHandle QPDF::getObject(QPDFObjGen const& og) { - if (auto it = m->obj_cache.find(og); it != m->obj_cache.end()) { - return {it->second.object}; - } else if (m->xref_table.initialized() && !m->xref_table.type(og)) { - return QPDF_Null::create(); - } else { - auto result = m->obj_cache.try_emplace(og, QPDF_Unresolved::create(this, og)); - return {result.first->second.object}; - } + return m->objects.get(og); } QPDFObjectHandle -QPDF::getObject(int objid, int generation) +QPDF::getObject(int id, int gen) { - return getObject(QPDFObjGen(objid, generation)); + return m->objects.get(id, gen); } QPDFObjectHandle QPDF::getObjectByObjGen(QPDFObjGen const& og) { - return getObject(og); + return m->objects.get(og); } QPDFObjectHandle -QPDF::getObjectByID(int objid, int generation) +QPDF::getObjectByID(int id, int gen) { - return getObject(QPDFObjGen(objid, generation)); + return m->objects.get(id, gen); } void -QPDF::replaceObject(int objid, int generation, QPDFObjectHandle oh) +QPDF::replaceObject(int id, int gen, QPDFObjectHandle replacement) { - replaceObject(QPDFObjGen(objid, generation), oh); + m->objects.replace(QPDFObjGen(id, gen), replacement); } void -QPDF::replaceObject(QPDFObjGen const& og, QPDFObjectHandle oh) +QPDF::replaceObject(QPDFObjGen const& og, QPDFObjectHandle replacement) { - if (!oh || (oh.isIndirect() && !(oh.isStream() && oh.getObjGen() == og))) { - QTC::TC("qpdf", "QPDF replaceObject called with indirect object"); - throw std::logic_error("QPDF::replaceObject called with indirect object handle"); - } - updateCache(og, oh.getObj()); -} - -void -QPDF::removeObject(QPDFObjGen og) -{ - if (auto cached = m->obj_cache.find(og); cached != m->obj_cache.end()) { - // Take care of any object handles that may be floating around. - cached->second.object->assign(QPDF_Null::create()); - cached->second.object->setObjGen(nullptr, QPDFObjGen()); - m->obj_cache.erase(cached); - } + m->objects.replace(og, replacement); } void @@ -2312,7 +599,7 @@ QPDF::replaceReserved(QPDFObjectHandle reserved, QPDFObjectHandle replacement) if (!(tc == ::ot_reserved || tc == ::ot_null)) { throw std::logic_error("replaceReserved called with non-reserved object"); } - replaceObject(reserved.getObjGen(), replacement); + m->objects.replace(reserved.getObjGen(), replacement); } QPDFObjectHandle @@ -2578,16 +865,13 @@ QPDF::copyStreamData(QPDFObjectHandle result, QPDFObjectHandle foreign) void QPDF::swapObjects(int objid1, int generation1, int objid2, int generation2) { - swapObjects(QPDFObjGen(objid1, generation1), QPDFObjGen(objid2, generation2)); + m->objects.swap(QPDFObjGen(objid1, generation1), QPDFObjGen(objid2, generation2)); } void QPDF::swapObjects(QPDFObjGen const& og1, QPDFObjGen const& og2) { - // Force objects to be read from the input source if needed, then swap them in the cache. - resolve(og1); - resolve(og2); - m->obj_cache[og1].object->swapWith(m->obj_cache[og2].object); + m->objects.swap(og1, og2); } unsigned long long @@ -2648,13 +932,13 @@ QPDF::getExtensionLevel() QPDFObjectHandle QPDF::getTrailer() { - return m->xref_table.trailer(); + return m->objects.trailer(); } QPDFObjectHandle QPDF::getRoot() { - QPDFObjectHandle root = m->xref_table.trailer().getKey("/Root"); + auto root = m->objects.trailer().getKey("/Root"); if (!root.isDictionary()) { throw damagedPDF("", 0, "unable to find /Root dictionary"); } else if ( @@ -2670,141 +954,10 @@ QPDF::getRoot() std::map QPDF::getXRefTable() { - if (!m->xref_table.initialized()) { + if (!m->objects.xref_table().initialized()) { throw std::logic_error("QPDF::getXRefTable called before parsing."); } - return m->xref_table.as_map(); -} - -size_t -QPDF::tableSize() -{ - // If obj_cache is dense, accommodate all object in tables,else accommodate only original - // objects. - auto max_xref = toI(m->xref_table.size()); - if (max_xref > 0) { - --max_xref; - } - auto max_obj = m->obj_cache.size() ? m->obj_cache.crbegin()->first.getObj() : 0; - auto max_id = std::numeric_limits::max() - 1; - if (max_obj >= max_id || max_xref >= max_id) { - // Temporary fix. Long-term solution is - // - QPDFObjGen to enforce objgens are valid and sensible - // - xref table and obj cache to protect against insertion of impossibly large obj ids - stopOnError("Impossibly large object id encountered."); - } - if (max_obj < 1.1 * std::max(toI(m->obj_cache.size()), max_xref)) { - return toS(++max_obj); - } - return toS(++max_xref); -} - -std::vector -QPDF::getCompressibleObjVector() -{ - return getCompressibleObjGens(); -} - -std::vector -QPDF::getCompressibleObjSet() -{ - return getCompressibleObjGens(); -} - -template -std::vector -QPDF::getCompressibleObjGens() -{ - // Return a list of objects that are allowed to be in object streams. Walk through the objects - // by traversing the document from the root, including a traversal of the pages tree. This - // makes that objects that are on the same page are more likely to be in the same object stream, - // which is slightly more efficient, particularly with linearized files. This is better than - // iterating through the xref table since it avoids preserving orphaned items. - - // Exclude encryption dictionary, if any - QPDFObjectHandle encryption_dict = m->xref_table.trailer().getKey("/Encrypt"); - QPDFObjGen encryption_dict_og = encryption_dict.getObjGen(); - - const size_t max_obj = getObjectCount(); - std::vector visited(max_obj, false); - std::vector queue; - queue.reserve(512); - queue.push_back(m->xref_table.trailer()); - std::vector result; - if constexpr (std::is_same_v) { - result.reserve(m->obj_cache.size()); - } else if constexpr (std::is_same_v) { - result.resize(max_obj + 1U, false); - } else { - throw std::logic_error("Unsupported type in QPDF::getCompressibleObjGens"); - } - while (!queue.empty()) { - auto obj = queue.back(); - queue.pop_back(); - if (obj.getObjectID() > 0) { - QPDFObjGen og = obj.getObjGen(); - const size_t id = toS(og.getObj() - 1); - if (id >= max_obj) { - throw std::logic_error( - "unexpected object id encountered in getCompressibleObjGens"); - } - if (visited[id]) { - QTC::TC("qpdf", "QPDF loop detected traversing objects"); - continue; - } - - // Check whether this is the current object. If not, remove it (which changes it into a - // direct null and therefore stops us from revisiting it) and move on to the next object - // in the queue. - auto upper = m->obj_cache.upper_bound(og); - if (upper != m->obj_cache.end() && upper->first.getObj() == og.getObj()) { - removeObject(og); - continue; - } - - visited[id] = true; - - if (og == encryption_dict_og) { - QTC::TC("qpdf", "QPDF exclude encryption dictionary"); - } else if (!(obj.isStream() || - (obj.isDictionaryOfType("/Sig") && obj.hasKey("/ByteRange") && - obj.hasKey("/Contents")))) { - if constexpr (std::is_same_v) { - result.push_back(og); - } else if constexpr (std::is_same_v) { - result[id + 1U] = true; - } - } - } - if (obj.isStream()) { - QPDFObjectHandle dict = obj.getDict(); - std::set keys = dict.getKeys(); - for (auto iter = keys.rbegin(); iter != keys.rend(); ++iter) { - std::string const& key = *iter; - QPDFObjectHandle value = dict.getKey(key); - if (key == "/Length") { - // omit stream lengths - if (value.isIndirect()) { - QTC::TC("qpdf", "QPDF exclude indirect length"); - } - } else { - queue.push_back(value); - } - } - } else if (obj.isDictionary()) { - std::set keys = obj.getKeys(); - for (auto iter = keys.rbegin(); iter != keys.rend(); ++iter) { - queue.push_back(obj.getKey(*iter)); - } - } else if (obj.isArray()) { - int n = obj.getArrayNItems(); - for (int i = 1; i <= n; ++i) { - queue.push_back(obj.getArrayItem(n - i)); - } - } - } - - return result; + return m->objects.xref_table().as_map(); } bool diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc index 436111b2..eacbd6c8 100644 --- a/libqpdf/QPDF_encryption.cc +++ b/libqpdf/QPDF_encryption.cc @@ -727,7 +727,7 @@ QPDF::initializeEncryption() // at /Encrypt again. Otherwise, things could go wrong if someone mutates the encryption // dictionary. - if (!m->xref_table.trailer().hasKey("/Encrypt")) { + if (!m->objects.trailer().hasKey("/Encrypt")) { return; } @@ -736,7 +736,7 @@ QPDF::initializeEncryption() m->encp->encrypted = true; std::string id1; - QPDFObjectHandle id_obj = m->xref_table.trailer().getKey("/ID"); + QPDFObjectHandle id_obj = m->objects.trailer().getKey("/ID"); if ((id_obj.isArray() && (id_obj.getArrayNItems() == 2) && id_obj.getArrayItem(0).isString())) { id1 = id_obj.getArrayItem(0).getStringValue(); } else { @@ -745,7 +745,7 @@ QPDF::initializeEncryption() warn(damagedPDF("trailer", "invalid /ID in trailer dictionary")); } - QPDFObjectHandle encryption_dict = m->xref_table.trailer().getKey("/Encrypt"); + QPDFObjectHandle encryption_dict = m->objects.trailer().getKey("/Encrypt"); if (!encryption_dict.isDictionary()) { throw damagedPDF("/Encrypt in trailer dictionary is not a dictionary"); } diff --git a/libqpdf/QPDF_json.cc b/libqpdf/QPDF_json.cc index 4bb5a9a3..13276cce 100644 --- a/libqpdf/QPDF_json.cc +++ b/libqpdf/QPDF_json.cc @@ -536,7 +536,7 @@ QPDF::JSONReactor::dictionaryItem(std::string const& key, JSON const& value) } else if (is_obj_key(key, obj, gen)) { this->cur_object = key; if (setNextStateIfDictionary(key, value, st_object_top)) { - next_obj = pdf.getObjectForJSON(obj, gen); + next_obj = pdf.objects().get_for_json(obj, gen); } } else { QTC::TC("qpdf", "QPDF_json bad object key"); @@ -582,7 +582,7 @@ QPDF::JSONReactor::dictionaryItem(std::string const& key, JSON const& value) this->saw_value = true; // The trailer must be a dictionary, so we can use setNextStateIfDictionary. if (setNextStateIfDictionary("trailer.value", value, st_object)) { - pdf.m->xref_table.trailer(makeObject(value)); + pdf.m->objects.xref_table().trailer(makeObject(value)); } } else if (key == "stream") { // Don't need to set saw_stream here since there's already an error. @@ -740,7 +740,7 @@ QPDF::JSONReactor::makeObject(JSON const& value) int gen = 0; std::string str; if (is_indirect_object(str_v, obj, gen)) { - result = pdf.getObjectForJSON(obj, gen); + result = pdf.objects().get_for_json(obj, gen); } else if (is_unicode_string(str_v, str)) { result = QPDFObjectHandle::newUnicodeString(str); } else if (is_binary_string(str_v, str)) { @@ -776,7 +776,7 @@ QPDF::createFromJSON(std::shared_ptr is) { m->pdf_version = "1.3"; m->no_input_name = is->getName(); - m->xref_table.initialize_json(); + m->objects.xref_table().initialize_json(); importJSON(is, true); } diff --git a/libqpdf/QPDF_linearization.cc b/libqpdf/QPDF_linearization.cc index 91787315..538d2df3 100644 --- a/libqpdf/QPDF_linearization.cc +++ b/libqpdf/QPDF_linearization.cc @@ -130,7 +130,7 @@ QPDF::isLinearized() return false; } - auto candidate = getObjectByID(lindict_obj, 0); + auto candidate = m->objects.get(lindict_obj, 0); if (!candidate.isDictionary()) { return false; } @@ -287,9 +287,9 @@ QPDF::readHintStream(Pipeline& pl, qpdf_offset_t offset, size_t length) { QPDFObjGen og; QPDFObjectHandle H = - readObjectAtOffset(false, offset, "linearization hint stream", QPDFObjGen(0, 0), og, false); - qpdf_offset_t min_end_offset = m->xref_table.end_before_space(og); - qpdf_offset_t max_end_offset = m->xref_table.end_after_space(og); + objects().read(false, offset, "linearization hint stream", QPDFObjGen(0, 0), og, false); + qpdf_offset_t min_end_offset = m->objects.xref_table().end_before_space(og); + qpdf_offset_t max_end_offset = m->objects.xref_table().end_after_space(og); if (!H.isStream()) { throw damagedPDF("linearization dictionary", "hint table is not a stream"); } @@ -303,8 +303,8 @@ QPDF::readHintStream(Pipeline& pl, qpdf_offset_t offset, size_t length) auto length_og = Hdict.getKey("/Length").getObjGen(); if (length_og.isIndirect()) { QTC::TC("qpdf", "QPDF hint table length indirect"); - min_end_offset = m->xref_table.end_before_space(length_og); - max_end_offset = m->xref_table.end_after_space(length_og); + min_end_offset = m->objects.xref_table().end_before_space(length_og); + max_end_offset = m->objects.xref_table().end_after_space(length_og); } else { QTC::TC("qpdf", "QPDF hint table length direct"); } @@ -441,7 +441,7 @@ QPDF::checkLinearizationInternal() for (size_t i = 0; i < toS(npages); ++i) { QPDFObjectHandle const& page = pages.at(i); QPDFObjGen og(page.getObjGen()); - if (m->xref_table.type(og) == 2) { + if (m->objects.xref_table().type(og) == 2) { linearizationWarning( "page dictionary for page " + std::to_string(i) + " is compressed"); } @@ -457,11 +457,11 @@ QPDF::checkLinearizationInternal() break; } } - if (m->file->tell() != m->xref_table.first_item_offset()) { + if (m->file->tell() != m->objects.xref_table().first_item_offset()) { QTC::TC("qpdf", "QPDF err /T mismatch"); linearizationWarning( "space before first xref item (/T) mismatch (computed = " + - std::to_string(m->xref_table.first_item_offset()) + + std::to_string(m->objects.xref_table().first_item_offset()) + "; file = " + std::to_string(m->file->tell())); } @@ -472,7 +472,7 @@ QPDF::checkLinearizationInternal() // compressed objects are supposed to be at the end of the containing xref section if any object // streams are in use. - if (m->xref_table.uncompressed_after_compressed()) { + if (m->objects.xref_table().uncompressed_after_compressed()) { linearizationWarning("linearized file contains an uncompressed object after a compressed " "one in a cross-reference stream"); } @@ -481,8 +481,8 @@ QPDF::checkLinearizationInternal() // make changes. If it has to, then the file is not properly linearized. We use the xref table // to figure out which objects are compressed and which are uncompressed. - optimize(m->xref_table); - calculateLinearizationData(m->xref_table); + optimize(m->objects); + calculateLinearizationData(m->objects); // E: offset of end of first page -- Implementation note 123 says Acrobat includes on extra // object here by mistake. pdlin fails to place thumbnail images in section 9, so when @@ -499,8 +499,8 @@ QPDF::checkLinearizationInternal() qpdf_offset_t max_E = -1; for (auto const& oh: m->part6) { QPDFObjGen og(oh.getObjGen()); - auto before = m->xref_table.end_before_space(og); - auto after = m->xref_table.end_after_space(og); + auto before = m->objects.xref_table().end_before_space(og); + auto after = m->objects.xref_table().end_after_space(og); if (before <= 0) { // All objects have to have been dereferenced to be classified. throw std::logic_error("linearization part6 object not in cache"); @@ -533,7 +533,7 @@ QPDF::maxEnd(ObjUser const& ou) } qpdf_offset_t end = 0; for (auto const& og: m->obj_user_to_objects[ou]) { - auto e = m->xref_table.end_after_space(og); + auto e = m->objects.xref_table().end_after_space(og); if (e <= 0) { stopOnError("unknown object referenced in object user table"); } @@ -545,13 +545,14 @@ QPDF::maxEnd(ObjUser const& ou) qpdf_offset_t QPDF::getLinearizationOffset(QPDFObjGen const& og) { - switch (m->xref_table.type(og)) { + switch (m->objects.xref_table().type(og)) { case 1: - return m->xref_table.offset(og); + return m->objects.xref_table().offset(og); case 2: // For compressed objects, return the offset of the object stream that contains them. - return getLinearizationOffset(QPDFObjGen(m->xref_table.stream_number(og.getObj()), 0)); + return getLinearizationOffset( + QPDFObjGen(m->objects.xref_table().stream_number(og.getObj()), 0)); default: stopOnError("getLinearizationOffset called for xref entry not of type 1 or 2"); @@ -562,22 +563,22 @@ QPDF::getLinearizationOffset(QPDFObjGen const& og) QPDFObjectHandle QPDF::getUncompressedObject(QPDFObjectHandle& obj, std::map const& object_stream_data) { - if (obj.isNull() || (object_stream_data.count(obj.getObjectID()) == 0)) { + if (obj.isNull() || !object_stream_data.count(obj.getObjectID())) { return obj; } else { int repl = (*(object_stream_data.find(obj.getObjectID()))).second; - return getObject(repl, 0); + return m->objects.get(repl, 0); } } QPDFObjectHandle -QPDF::getUncompressedObject(QPDFObjectHandle& obj, Xref_table const& xref) +QPDF::getUncompressedObject(QPDFObjectHandle& obj, Objects const& objects) { auto og = obj.getObjGen(); - if (obj.isNull() || xref.type(og) != 2) { + if (obj.isNull() || objects.xref_table().type(og) != 2) { return obj; } - return getObject(xref.stream_number(og.getObj()), 0); + return m->objects.get(objects.xref_table().stream_number(og.getObj()), 0); } QPDFObjectHandle @@ -585,7 +586,7 @@ QPDF::getUncompressedObject(QPDFObjectHandle& oh, QPDFWriter::ObjTable const& ob { if (obj.contains(oh)) { if (auto id = obj[oh].object_stream; id > 0) { - return oh.isNull() ? oh : getObject(id, 0); + return oh.isNull() ? oh : m->objects.get(id, 0); } } return oh; @@ -597,7 +598,7 @@ QPDF::lengthNextN(int first_object, int n) int length = 0; for (int i = 0; i < n; ++i) { QPDFObjGen og(first_object + i, 0); - auto end = m->xref_table.end_after_space(og); + auto end = m->objects.xref_table().end_after_space(og); if (end <= 0) { linearizationWarning( "no xref table entry for " + std::to_string(first_object + i) + " 0"); @@ -627,7 +628,7 @@ QPDF::checkHPageOffset( int npages = toI(pages.size()); qpdf_offset_t table_offset = adjusted_offset(m->page_offset_hints.first_page_offset); QPDFObjGen first_page_og(pages.at(0).getObjGen()); - if (m->xref_table.type(first_page_og) == 0) { + if (m->objects.xref_table().type(first_page_og) == 0) { stopOnError("supposed first page object is not known"); } qpdf_offset_t offset = getLinearizationOffset(first_page_og); @@ -638,7 +639,7 @@ QPDF::checkHPageOffset( for (int pageno = 0; pageno < npages; ++pageno) { QPDFObjGen page_og(pages.at(toS(pageno)).getObjGen()); int first_object = page_og.getObj(); - if (m->xref_table.type(page_og) == 0) { + if (m->objects.xref_table().type(page_og) == 0) { stopOnError("unknown object in page offset hint table"); } offset = getLinearizationOffset(page_og); @@ -760,7 +761,7 @@ QPDF::checkHSharedObject(std::vector const& pages, std::mapxref_table.type(og) == 0) { + if (m->objects.xref_table().type(og) == 0) { stopOnError("unknown object in shared object hint table"); } qpdf_offset_t offset = getLinearizationOffset(og); @@ -811,7 +812,7 @@ QPDF::checkHOutlines() return; } QPDFObjGen og(outlines.getObjGen()); - if (m->xref_table.type(og) == 0) { + if (m->objects.xref_table().type(og) == 0) { stopOnError("unknown object in outlines hint table"); } qpdf_offset_t offset = getLinearizationOffset(og); @@ -1158,7 +1159,7 @@ QPDF::calculateLinearizationData(T const& object_stream_data) // Map all page objects to the containing object stream. This should be a no-op in a // properly linearized file. for (auto oh: getAllPages()) { - pages.push_back(getUncompressedObject(oh, object_stream_data)); + pages.emplace_back(getUncompressedObject(oh, object_stream_data)); } } int npages = toI(pages.size()); @@ -1429,9 +1430,9 @@ QPDF::pushOutlinesToPart( m->c_outline_data.first_object = outlines_og.getObj(); m->c_outline_data.nobjects = 1; lc_outlines.erase(outlines_og); - part.push_back(outlines); + part.emplace_back(outlines); for (auto const& og: lc_outlines) { - part.push_back(getObject(og)); + part.emplace_back(m->objects.get(og)); ++m->c_outline_data.nobjects; } } diff --git a/libqpdf/QPDF_objects.cc b/libqpdf/QPDF_objects.cc new file mode 100644 index 00000000..63eb13a4 --- /dev/null +++ b/libqpdf/QPDF_objects.cc @@ -0,0 +1,1944 @@ +#include // include first for large file support + +#include + +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +using Objects = QPDF::Objects; +using Xref_table = Objects::Xref_table; + +namespace +{ + class InvalidInputSource final: public InputSource + { + public: + InvalidInputSource(std::string const& name) : + name(name) + { + } + ~InvalidInputSource() final = default; + qpdf_offset_t + findAndSkipNextEOL() final + { + throwException(); + return 0; + } + std::string const& + getName() const final + { + return name; + } + qpdf_offset_t + tell() final + { + throwException(); + return 0; + } + void + seek(qpdf_offset_t offset, int whence) final + { + throwException(); + } + void + rewind() final + { + throwException(); + } + size_t + read(char* buffer, size_t length) final + { + throwException(); + return 0; + } + void + unreadCh(char ch) final + { + throwException(); + } + + private: + void + throwException() + { + throw std::logic_error("QPDF operation attempted on a QPDF object with no input " + "source. QPDF operations are invalid before processFile (or " + "another process method) or after closeInputSource"); + } + + std::string const& name; + }; +} // namespace + +bool +QPDF::findStartxref() +{ + if (readToken(*m->file).isWord("startxref") && readToken(*m->file).isInteger()) { + // Position in front of offset token + m->file->seek(m->file->getLastOffset(), SEEK_SET); + return true; + } + return false; +} + +void +Xref_table::initialize_empty() +{ + initialized_ = true; + trailer_ = QPDFObjectHandle::newDictionary(); + auto rt = qpdf.makeIndirectObject(QPDFObjectHandle::newDictionary()); + auto pgs = qpdf.makeIndirectObject(QPDFObjectHandle::newDictionary()); + pgs.replaceKey("/Type", QPDFObjectHandle::newName("/Pages")); + pgs.replaceKey("/Kids", QPDFObjectHandle::newArray()); + pgs.replaceKey("/Count", QPDFObjectHandle::newInteger(0)); + rt.replaceKey("/Type", QPDFObjectHandle::newName("/Catalog")); + rt.replaceKey("/Pages", pgs); + trailer_.replaceKey("/Root", rt); + trailer_.replaceKey("/Size", QPDFObjectHandle::newInteger(3)); +} + +void +Xref_table::initialize_json() +{ + initialized_ = true; + table.resize(1); + trailer_ = QPDFObjectHandle::newDictionary(); + trailer_.replaceKey("/Size", QPDFObjectHandle::newInteger(1)); +} + +void +Xref_table::initialize() +{ + // PDF spec says %%EOF must be found within the last 1024 bytes of/ the file. We add an extra + // 30 characters to leave room for the startxref stuff. + file->seek(0, SEEK_END); + qpdf_offset_t end_offset = file->tell(); + // Sanity check on object ids. All objects must appear in xref table / stream. In all realistic + // scenarios at least 3 bytes are required. + if (max_id_ > end_offset / 3) { + max_id_ = static_cast(end_offset / 3); + } + qpdf_offset_t start_offset = (end_offset > 1054 ? end_offset - 1054 : 0); + PatternFinder sf(qpdf, &QPDF::findStartxref); + qpdf_offset_t xref_offset = 0; + if (file->findLast("startxref", start_offset, 0, sf)) { + xref_offset = QUtil::string_to_ll(read_token().getValue().c_str()); + } + + try { + if (xref_offset == 0) { + QTC::TC("qpdf", "QPDF can't find startxref"); + throw damaged_pdf("can't find startxref"); + } + try { + read(xref_offset); + } catch (QPDFExc&) { + throw; + } catch (std::exception& e) { + throw damaged_pdf(std::string("error reading xref: ") + e.what()); + } + } catch (QPDFExc& e) { + if (attempt_recovery_) { + reconstruct(e); + QTC::TC("qpdf", "QPDF reconstructed xref table"); + } else { + throw; + } + } + + initialized_ = true; +} + +void +Xref_table::reconstruct(QPDFExc& e) +{ + if (reconstructed_) { + // Avoid xref reconstruction infinite loops. This is getting very hard to reproduce because + // qpdf is throwing many fewer exceptions while parsing. Most situations are warnings now. + throw e; + } + + // If recovery generates more than 1000 warnings, the file is so severely damaged that there + // probably is no point trying to continue. + const auto max_warnings = qpdf.m->warnings.size() + 1000U; + auto check_warnings = [this, max_warnings]() { + if (qpdf.m->warnings.size() > max_warnings) { + throw damaged_pdf("too many errors while reconstructing cross-reference table"); + } + }; + + reconstructed_ = true; + // We may find more objects, which may contain dangling references. + qpdf.m->fixed_dangling_refs = false; + + warn_damaged("file is damaged"); + qpdf.warn(e); + warn_damaged("Attempting to reconstruct cross-reference table"); + + // Delete all references to type 1 (uncompressed) objects + for (auto& iter: table) { + if (iter.type() == 1) { + iter = {}; + } + } + + std::vector> found_objects; + std::vector trailers; + int max_found = 0; + + file->seek(0, SEEK_END); + qpdf_offset_t eof = file->tell(); + file->seek(0, SEEK_SET); + // Don't allow very long tokens here during recovery. All the interesting tokens are covered. + static size_t const MAX_LEN = 10; + while (file->tell() < eof) { + QPDFTokenizer::Token t1 = read_token(MAX_LEN); + qpdf_offset_t token_start = file->tell() - toO(t1.getValue().length()); + if (t1.isInteger()) { + auto pos = file->tell(); + QPDFTokenizer::Token t2 = read_token(MAX_LEN); + if (t2.isInteger() && read_token(MAX_LEN).isWord("obj")) { + int obj = QUtil::string_to_int(t1.getValue().c_str()); + int gen = QUtil::string_to_int(t2.getValue().c_str()); + if (obj <= max_id_) { + found_objects.emplace_back(obj, gen, token_start); + if (obj > max_found) { + max_found = obj; + } + } else { + warn_damaged("ignoring object with impossibly large id " + std::to_string(obj)); + } + } + file->seek(pos, SEEK_SET); + } else if (!trailer_ && t1.isWord("trailer")) { + trailers.emplace_back(file->tell()); + } + file->findAndSkipNextEOL(); + } + + table.resize(toS(max_found) + 1); + + for (auto tr: trailers) { + file->seek(tr, SEEK_SET); + auto t = read_trailer(); + if (!t.isDictionary()) { + // Oh well. It was worth a try. + } else { + trailer_ = t; + break; + } + check_warnings(); + } + + auto rend = found_objects.rend(); + for (auto it = found_objects.rbegin(); it != rend; it++) { + auto [obj, gen, token_start] = *it; + insert(obj, 1, token_start, gen); + check_warnings(); + } + + if (!trailer_) { + qpdf_offset_t max_offset{0}; + // If there are any xref streams, take the last one to appear. + int i = -1; + for (auto const& item: table) { + ++i; + if (item.type() != 1) { + continue; + } + auto oh = objects.get(i, item.gen()); + try { + if (!oh.isStreamOfType("/XRef")) { + continue; + } + } catch (std::exception&) { + continue; + } + auto offset = item.offset(); + if (offset > max_offset) { + max_offset = offset; + trailer_ = oh.getDict(); + } + check_warnings(); + } + if (max_offset > 0) { + try { + read(max_offset); + } catch (std::exception&) { + throw damaged_pdf( + "error decoding candidate xref stream while recovering damaged file"); + } + QTC::TC("qpdf", "QPDF recover xref stream"); + } + } + + if (!trailer_) { + // We could check the last encountered object to see if it was an xref stream. If so, we + // could try to get the trailer from there. This may make it possible to recover files with + // bad startxref pointers even when they have object streams. + + throw damaged_pdf("unable to find trailer dictionary while recovering damaged file"); + } + if (table.empty()) { + // We cannot check for an empty xref table in parse because empty tables are valid when + // creating QPDF objects from JSON. + throw damaged_pdf("unable to find objects while recovering damaged file"); + } + check_warnings(); + if (!initialized_) { + initialized_ = true; + qpdf.getAllPages(); + check_warnings(); + if (qpdf.m->all_pages.empty()) { + initialized_ = false; + throw damaged_pdf("unable to find any pages while recovering damaged file"); + } + } + // We could iterate through the objects looking for streams and try to find objects inside of + // them, but it's probably not worth the trouble. Acrobat can't recover files with any errors + // in an xref stream, and this would be a real long shot anyway. If we wanted to do anything + // that involved looking at stream contents, we'd also have to call initializeEncryption() here. + // It's safe to call it more than once. +} + +void +Xref_table::read(qpdf_offset_t xref_offset) +{ + std::map free_table; + std::set visited; + while (xref_offset) { + visited.insert(xref_offset); + char buf[7]; + memset(buf, 0, sizeof(buf)); + file->seek(xref_offset, SEEK_SET); + // Some files miss the mark a little with startxref. We could do a better job of searching + // in the neighborhood for something that looks like either an xref table or stream, but the + // simple heuristic of skipping whitespace can help with the xref table case and is harmless + // with the stream case. + bool done = false; + bool skipped_space = false; + while (!done) { + char ch; + if (1 == file->read(&ch, 1)) { + if (QUtil::is_space(ch)) { + skipped_space = true; + } else { + file->unreadCh(ch); + done = true; + } + } else { + QTC::TC("qpdf", "QPDF eof skipping spaces before xref", skipped_space ? 0 : 1); + done = true; + } + } + + file->read(buf, sizeof(buf) - 1); + // The PDF spec says xref must be followed by a line terminator, but files exist in the wild + // where it is terminated by arbitrary whitespace. + if ((strncmp(buf, "xref", 4) == 0) && QUtil::is_space(buf[4])) { + if (skipped_space) { + QTC::TC("qpdf", "QPDF xref skipped space"); + warn_damaged("extraneous whitespace seen before xref"); + } + QTC::TC( + "qpdf", + "QPDF xref space", + ((buf[4] == '\n') ? 0 + : (buf[4] == '\r') ? 1 + : (buf[4] == ' ') ? 2 + : 9999)); + int skip = 4; + // buf is null-terminated, and QUtil::is_space('\0') is false, so this won't overrun. + while (QUtil::is_space(buf[skip])) { + ++skip; + } + xref_offset = process_section(xref_offset + skip); + } else { + xref_offset = read_stream(xref_offset); + } + if (visited.count(xref_offset) != 0) { + QTC::TC("qpdf", "QPDF xref loop"); + throw damaged_pdf("loop detected following xref tables"); + } + } + + if (!trailer_) { + throw damaged_pdf("unable to find trailer while reading xref"); + } + int size = trailer_.getKey("/Size").getIntValueAsInt(); + + if (size < 3) { + throw damaged_pdf("too few objects - file can't have a page tree"); + } + + // We are no longer reporting what the highest id in the xref table is. I don't think it adds + // anything. If we want to report more detail, we should report the total number of missing + // entries, including missing entries before the last actual entry. +} + +Xref_table::Subsection +Xref_table::subsection(std::string const& line) +{ + auto terminate = [this]() -> void { + QTC::TC("qpdf", "QPDF invalid xref"); + throw damaged_table("xref syntax invalid"); + }; + + // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated + // buffer. + char const* p = line.c_str(); + char const* start = line.c_str(); + + // Skip zero or more spaces + while (QUtil::is_space(*p)) { + ++p; + } + // Require digit + if (!QUtil::is_digit(*p)) { + terminate(); + } + // Gather digits + std::string obj_str; + while (QUtil::is_digit(*p)) { + obj_str.append(1, *p++); + } + // Require space + if (!QUtil::is_space(*p)) { + terminate(); + } + // Skip spaces + while (QUtil::is_space(*p)) { + ++p; + } + // Require digit + if (!QUtil::is_digit(*p)) { + terminate(); + } + // Gather digits + std::string num_str; + while (QUtil::is_digit(*p)) { + num_str.append(1, *p++); + } + // Skip any space including line terminators + while (QUtil::is_space(*p)) { + ++p; + } + auto obj = QUtil::string_to_int(obj_str.c_str()); + auto count = QUtil::string_to_int(num_str.c_str()); + if (obj > max_id() || count > max_id() || (obj + count) > max_id()) { + throw damaged_table("xref table subsection header contains impossibly large entry"); + } + return {obj, count, file->getLastOffset() + toI(p - start)}; +} + +std::vector +Xref_table::bad_subsections(std::string& line, qpdf_offset_t start) +{ + std::vector result; + file->seek(start, SEEK_SET); + + while (true) { + line.assign(50, '\0'); + file->read(line.data(), line.size()); + auto [obj, num, offset] = result.emplace_back(subsection(line)); + file->seek(offset, SEEK_SET); + for (qpdf_offset_t i = obj; i - num < obj; ++i) { + if (!std::get<0>(read_entry())) { + QTC::TC("qpdf", "QPDF invalid xref entry"); + throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")"); + } + } + qpdf_offset_t pos = file->tell(); + if (read_token().isWord("trailer")) { + return result; + } else { + file->seek(pos, SEEK_SET); + } + } +} + +// Optimistically read and parse all subsection headers. If an error is encountered return the +// result of bad_subsections. +std::vector +Xref_table::subsections(std::string& line) +{ + auto recovery_offset = file->tell(); + try { + std::vector result; + + while (true) { + line.assign(50, '\0'); + file->read(line.data(), line.size()); + auto& sub = result.emplace_back(subsection(line)); + auto count = std::get<1>(sub); + auto offset = std::get<2>(sub); + file->seek(offset + 20 * toO(count) - 1, SEEK_SET); + file->read(line.data(), 1); + if (!(line[0] == '\n' || line[0] == '\n')) { + return bad_subsections(line, recovery_offset); + } + qpdf_offset_t pos = file->tell(); + if (read_token().isWord("trailer")) { + return result; + } else { + file->seek(pos, SEEK_SET); + } + } + } catch (...) { + return bad_subsections(line, recovery_offset); + } +} + +// Returns (success, f1, f2, type). +std::tuple +Xref_table::read_bad_entry() +{ + qpdf_offset_t f1{0}; + int f2{0}; + char type{'\0'}; + // Reposition after initial read attempt and reread. + file->seek(file->getLastOffset(), SEEK_SET); + auto line = file->readLine(30); + + // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated + // buffer. + char const* p = line.data(); + + // Skip zero or more spaces. There aren't supposed to be any. + bool invalid = false; + while (QUtil::is_space(*p)) { + ++p; + QTC::TC("qpdf", "QPDF ignore first space in xref entry"); + invalid = true; + } + // Require digit + if (!QUtil::is_digit(*p)) { + return {false, 0, 0, '\0'}; + } + // Gather digits + std::string f1_str; + while (QUtil::is_digit(*p)) { + f1_str.append(1, *p++); + } + // Require space + if (!QUtil::is_space(*p)) { + return {false, 0, 0, '\0'}; + } + if (QUtil::is_space(*(p + 1))) { + QTC::TC("qpdf", "QPDF ignore first extra space in xref entry"); + invalid = true; + } + // Skip spaces + while (QUtil::is_space(*p)) { + ++p; + } + // Require digit + if (!QUtil::is_digit(*p)) { + return {false, 0, 0, '\0'}; + } + // Gather digits + std::string f2_str; + while (QUtil::is_digit(*p)) { + f2_str.append(1, *p++); + } + // Require space + if (!QUtil::is_space(*p)) { + return {false, 0, 0, '\0'}; + } + if (QUtil::is_space(*(p + 1))) { + QTC::TC("qpdf", "QPDF ignore second extra space in xref entry"); + invalid = true; + } + // Skip spaces + while (QUtil::is_space(*p)) { + ++p; + } + if ((*p == 'f') || (*p == 'n')) { + type = *p; + } else { + return {false, 0, 0, '\0'}; + } + if ((f1_str.length() != 10) || (f2_str.length() != 5)) { + QTC::TC("qpdf", "QPDF ignore length error xref entry"); + invalid = true; + } + + if (invalid) { + qpdf.warn(damaged_table("accepting invalid xref table entry")); + } + + f1 = QUtil::string_to_ll(f1_str.c_str()); + f2 = QUtil::string_to_int(f2_str.c_str()); + + return {true, f1, f2, type}; +} + +// Optimistically read and parse xref entry. If entry is bad, call read_bad_xrefEntry and return +// result. Returns (success, f1, f2, type). +std::tuple +Xref_table::read_entry() +{ + qpdf_offset_t f1{0}; + int f2{0}; + char type{'\0'}; + std::array line; + f1 = 0; + f2 = 0; + if (file->read(line.data(), 20) != 20) { + // C++20: [[unlikely]] + return {false, 0, 0, '\0'}; + } + line[20] = '\0'; + char const* p = line.data(); + + int f1_len = 0; + int f2_len = 0; + + // is_space and is_digit both return false on '\0', so this will not overrun the null-terminated + // buffer. + + // Gather f1 digits. NB No risk of overflow as 9'999'999'999 < max long long. + while (*p == '0') { + ++f1_len; + ++p; + } + while (QUtil::is_digit(*p) && f1_len++ < 10) { + f1 *= 10; + f1 += *p++ - '0'; + } + // Require space + if (!QUtil::is_space(*p++)) { + // Entry doesn't start with space or digit. + // C++20: [[unlikely]] + return {false, 0, 0, '\0'}; + } + // Gather digits. NB No risk of overflow as 99'999 < max int. + while (*p == '0') { + ++f2_len; + ++p; + } + while (QUtil::is_digit(*p) && f2_len++ < 5) { + f2 *= 10; + f2 += static_cast(*p++ - '0'); + } + if (QUtil::is_space(*p++) && (*p == 'f' || *p == 'n')) { + // C++20: [[likely]] + type = *p; + // No test for valid line[19]. + if (*(++p) && *(++p) && (*p == '\n' || *p == '\r') && f1_len == 10 && f2_len == 5) { + // C++20: [[likely]] + return {true, f1, f2, type}; + } + } + return read_bad_entry(); +} + +// Read a single cross-reference table section and associated trailer. +qpdf_offset_t +Xref_table::process_section(qpdf_offset_t xref_offset) +{ + file->seek(xref_offset, SEEK_SET); + std::string line; + auto subs = subsections(line); + + auto cur_trailer_offset = file->tell(); + auto cur_trailer = read_trailer(); + if (!cur_trailer.isDictionary()) { + QTC::TC("qpdf", "QPDF missing trailer"); + throw qpdf.damagedPDF("", "expected trailer dictionary"); + } + + if (!trailer_) { + unsigned int sz; + trailer_ = cur_trailer; + + if (!trailer_.hasKey("/Size")) { + QTC::TC("qpdf", "QPDF trailer lacks size"); + throw qpdf.damagedPDF("trailer", "trailer dictionary lacks /Size key"); + } + if (!trailer_.getKey("/Size").getValueAsUInt(sz)) { + QTC::TC("qpdf", "QPDF trailer size not integer"); + throw qpdf.damagedPDF("trailer", "/Size key in trailer dictionary is not an integer"); + } + if (sz >= static_cast(max_id_)) { + QTC::TC("qpdf", "QPDF trailer size impossibly large"); + throw qpdf.damagedPDF("trailer", "/Size key in trailer dictionary is impossibly large"); + } + table.resize(sz); + } + + for (auto [obj, num, offset]: subs) { + file->seek(offset, SEEK_SET); + for (qpdf_offset_t i = obj; i - num < obj; ++i) { + if (i == 0) { + // This is needed by checkLinearization() + first_item_offset_ = file->tell(); + } + // For xref_table, these will always be small enough to be ints + auto [success, f1, f2, type] = read_entry(); + if (!success) { + throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")"); + } + if (type == 'f') { + insert_free(QPDFObjGen(toI(i), f2)); + } else { + insert(toI(i), 1, f1, f2); + } + } + qpdf_offset_t pos = file->tell(); + if (read_token().isWord("trailer")) { + break; + } else { + file->seek(pos, SEEK_SET); + } + } + + if (cur_trailer.hasKey("/XRefStm")) { + if (ignore_streams_) { + QTC::TC("qpdf", "QPDF ignoring XRefStm in trailer"); + } else { + if (cur_trailer.getKey("/XRefStm").isInteger()) { + // Read the xref stream but disregard any return value -- we'll use our trailer's + // /Prev key instead of the xref stream's. + (void)read_stream(cur_trailer.getKey("/XRefStm").getIntValue()); + } else { + throw qpdf.damagedPDF("xref stream", cur_trailer_offset, "invalid /XRefStm"); + } + } + } + + if (cur_trailer.hasKey("/Prev")) { + if (!cur_trailer.getKey("/Prev").isInteger()) { + QTC::TC("qpdf", "QPDF trailer prev not integer"); + throw qpdf.damagedPDF( + "trailer", cur_trailer_offset, "/Prev key in trailer dictionary is not an integer"); + } + QTC::TC("qpdf", "QPDF prev key in trailer dictionary"); + return cur_trailer.getKey("/Prev").getIntValue(); + } + + return 0; +} + +// Read a single cross-reference stream. +qpdf_offset_t +Xref_table::read_stream(qpdf_offset_t xref_offset) +{ + if (!ignore_streams_) { + QPDFObjGen x_og; + QPDFObjectHandle xref_obj; + try { + xref_obj = + objects.read(false, xref_offset, "xref stream", QPDFObjGen(0, 0), x_og, true); + } catch (QPDFExc&) { + // ignore -- report error below + } + if (xref_obj.isStreamOfType("/XRef")) { + QTC::TC("qpdf", "QPDF found xref stream"); + return process_stream(xref_offset, xref_obj); + } + } + + QTC::TC("qpdf", "QPDF can't find xref"); + throw qpdf.damagedPDF("", xref_offset, "xref not found"); + return 0; // unreachable +} + +// Return the entry size of the xref stream and the processed W array. +std::pair> +Xref_table::process_W(QPDFObjectHandle& dict, std::function damaged) +{ + auto W_obj = dict.getKey("/W"); + if (!(W_obj.isArray() && W_obj.getArrayNItems() >= 3 && W_obj.getArrayItem(0).isInteger() && + W_obj.getArrayItem(1).isInteger() && W_obj.getArrayItem(2).isInteger())) { + throw damaged("Cross-reference stream does not have a proper /W key"); + } + + std::array W; + int entry_size = 0; + auto w_vector = W_obj.getArrayAsVector(); + int max_bytes = sizeof(qpdf_offset_t); + for (size_t i = 0; i < 3; ++i) { + W[i] = w_vector[i].getIntValueAsInt(); + if (W[i] > max_bytes) { + throw damaged("Cross-reference stream's /W contains impossibly large values"); + } + if (W[i] < 0) { + throw damaged("Cross-reference stream's /W contains negative values"); + } + entry_size += W[i]; + } + if (entry_size == 0) { + throw damaged("Cross-reference stream's /W indicates entry size of 0"); + } + return {entry_size, W}; +} + +// Validate Size entry and return the maximum number of entries that the xref stream can contain and +// the value of the Size entry. +std::pair +Xref_table::process_Size( + QPDFObjectHandle& dict, int entry_size, std::function damaged) +{ + // Number of entries is limited by the highest possible object id and stream size. + auto max_num_entries = std::numeric_limits::max(); + if (max_num_entries > (std::numeric_limits::max() / entry_size)) { + max_num_entries = toI(std::numeric_limits::max() / entry_size); + } + + auto Size_obj = dict.getKey("/Size"); + long long size; + if (!dict.getKey("/Size").getValueAsInt(size)) { + throw damaged("Cross-reference stream does not have a proper /Size key"); + } else if (size < 0) { + throw damaged("Cross-reference stream has a negative /Size key"); + } else if (size >= max_num_entries) { + throw damaged("Cross-reference stream has an impossibly large /Size key"); + } + // We are not validating that Size <= (Size key of parent xref / trailer). + return {max_num_entries, toS(size)}; +} + +// Return the number of entries of the xref stream and the processed Index array. +std::pair>> +Xref_table::process_Index( + QPDFObjectHandle& dict, int max_num_entries, std::function damaged) +{ + auto size = dict.getKey("/Size").getIntValueAsInt(); + auto Index_obj = dict.getKey("/Index"); + + if (Index_obj.isArray()) { + std::vector> indx; + int num_entries = 0; + auto index_vec = Index_obj.getArrayAsVector(); + if ((index_vec.size() % 2) || index_vec.size() < 2) { + throw damaged("Cross-reference stream's /Index has an invalid number of values"); + } + + int i = 0; + long long first = 0; + for (auto& val: index_vec) { + if (val.isInteger()) { + if (i % 2) { + auto count = val.getIntValue(); + if (count <= 0) { + throw damaged( + "Cross-reference stream section claims to contain " + + std::to_string(count) + " entries"); + } + // We are guarding against the possibility of num_entries * entry_size + // overflowing. We are not checking that entries are in ascending order as + // required by the spec, which probably should generate a warning. We are also + // not checking that for each subsection first object number + number of entries + // <= /Size. The spec requires us to ignore object number > /Size. + if (first > (max_num_entries - count) || + count > (max_num_entries - num_entries)) { + throw damaged( + "Cross-reference stream claims to contain too many entries: " + + std::to_string(first) + " " + std::to_string(max_num_entries) + " " + + std::to_string(num_entries)); + } + indx.emplace_back(static_cast(first), static_cast(count)); + num_entries += static_cast(count); + } else { + first = val.getIntValue(); + if (first < 0) { + throw damaged( + "Cross-reference stream's /Index contains a negative object id"); + } else if (first > max_num_entries) { + throw damaged("Cross-reference stream's /Index contains an impossibly " + "large object id"); + } + } + } else { + throw damaged( + "Cross-reference stream's /Index's item " + std::to_string(i) + + " is not an integer"); + } + i++; + } + QTC::TC("qpdf", "QPDF xref /Index is array", index_vec.size() == 2 ? 0 : 1); + return {num_entries, indx}; + } else if (Index_obj.isNull()) { + QTC::TC("qpdf", "QPDF xref /Index is null"); + return {size, {{0, size}}}; + } else { + throw damaged("Cross-reference stream does not have a proper /Index key"); + } +} + +qpdf_offset_t +Xref_table::process_stream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj) +{ + auto damaged = [this, xref_offset](std::string_view msg) -> QPDFExc { + return qpdf.damagedPDF("xref stream", xref_offset, msg.data()); + }; + + auto dict = xref_obj.getDict(); + + auto [entry_size, W] = process_W(dict, damaged); + auto [max_num_entries, size] = process_Size(dict, entry_size, damaged); + auto [num_entries, indx] = process_Index(dict, max_num_entries, damaged); + + std::shared_ptr bp = xref_obj.getStreamData(qpdf_dl_specialized); + size_t actual_size = bp->getSize(); + auto expected_size = toS(entry_size) * toS(num_entries); + + if (expected_size != actual_size) { + QPDFExc x = damaged( + "Cross-reference stream data has the wrong size; expected = " + + std::to_string(expected_size) + "; actual = " + std::to_string(actual_size)); + if (expected_size > actual_size) { + throw x; + } else { + qpdf.warn(x); + } + } + + if (!trailer_) { + trailer_ = dict; + if (size > toS(max_id_)) { + throw damaged("Cross-reference stream /Size entry is impossibly large"); + } + table.resize(size); + } + + bool saw_first_compressed_object = false; + + // Actual size vs. expected size check above ensures that we will not overflow any buffers here. + // We know that entry_size * num_entries is less or equal to the size of the buffer. + auto p = bp->getBuffer(); + for (auto [obj, sec_entries]: indx) { + // Process a subsection. + for (int i = 0; i < sec_entries; ++i) { + // Read this entry + std::array fields{}; + if (W[0] == 0) { + QTC::TC("qpdf", "QPDF default for xref stream field 0"); + fields[0] = 1; + } + for (size_t j = 0; j < 3; ++j) { + for (int k = 0; k < W[j]; ++k) { + fields[j] <<= 8; + fields[j] |= *p++; + } + } + + // Get the generation number. The generation number is 0 unless this is an uncompressed + // object record, in which case the generation number appears as the third field. + if (saw_first_compressed_object) { + if (fields[0] != 2) { + uncompressed_after_compressed_ = true; + } + } else if (fields[0] == 2) { + saw_first_compressed_object = true; + } + if (obj == 0) { + // This is needed by checkLinearization() + first_item_offset_ = xref_offset; + } else if (fields[0] == 0) { + // Ignore fields[2], which we don't care about in this case. This works around the + // issue of some PDF files that put invalid values, like -1, here for deleted + // objects. + insert_free(QPDFObjGen(obj, 0)); + } else { + insert(obj, toI(fields[0]), fields[1], toI(fields[2])); + } + ++obj; + } + } + + if (dict.hasKey("/Prev")) { + if (!dict.getKey("/Prev").isInteger()) { + throw qpdf.damagedPDF( + "xref stream", "/Prev key in xref stream dictionary is not an integer"); + } + QTC::TC("qpdf", "QPDF prev key in xref stream dictionary"); + return dict.getKey("/Prev").getIntValue(); + } else { + return 0; + } +} + +void +Xref_table::insert(int obj, int f0, qpdf_offset_t f1, int f2) +{ + // Populate the xref table in such a way that the first reference to an object that we see, + // which is the one in the latest xref table in which it appears, is the one that gets stored. + // This works because we are reading more recent appends before older ones. + + // If there is already an entry for this object and generation in the table, it means that a + // later xref table has registered this object. Disregard this one. + + int new_gen = f0 == 2 ? 0 : f2; + + if (!(obj > 0 && static_cast(obj) < table.size() && 0 <= f2 && new_gen < 65535)) { + // We are ignoring invalid objgens. Most will arrive here from xref reconstruction. There + // is probably no point having another warning but we could count invalid items in order to + // decide when to give up. + QTC::TC("qpdf", "QPDF xref overwrite invalid objgen"); + return; + } + + auto& entry = table[static_cast(obj)]; + auto old_type = entry.type(); + + if (!old_type && entry.gen() > 0) { + // At the moment we are processing the updates last to first and therefore the gen doesn't + // matter as long as it > 0 to distinguish it from an uninitialized entry. This will need + // to be revisited when we want to support incremental updates or more comprehensive + // checking. + QTC::TC("qpdf", "QPDF xref deleted object"); + return; + } + + if (f0 == 2 && static_cast(f1) == obj) { + qpdf.warn(qpdf.damagedPDF( + "xref stream", "self-referential object stream " + std::to_string(obj))); + return; + } + + if (old_type && entry.gen() >= new_gen) { + QTC::TC("qpdf", "QPDF xref reused object"); + return; + } + + switch (f0) { + case 1: + // f2 is generation + QTC::TC("qpdf", "QPDF xref gen > 0", (f2 > 0) ? 1 : 0); + entry = {f2, Uncompressed(f1)}; + break; + + case 2: + entry = {0, Compressed(toI(f1), f2)}; + object_streams_ = true; + break; + + default: + throw qpdf.damagedPDF( + "xref stream", "unknown xref stream entry type " + std::to_string(f0)); + break; + } +} + +void +Xref_table::insert_free(QPDFObjGen og) +{ + // At the moment we are processing the updates last to first and therefore the gen doesn't + // matter as long as it > 0 to distinguish it from an uninitialized entry. This will need to be + // revisited when we want to support incremental updates or more comprehensive checking. + if (og.getObj() < 1) { + return; + } + size_t id = static_cast(og.getObj()); + if (id < table.size() && !type(id)) { + table[id] = {1, {}}; + } +} + +QPDFObjGen +Xref_table::at_offset(qpdf_offset_t offset) const noexcept +{ + int id = 0; + int gen = 0; + qpdf_offset_t start = 0; + + int i = 0; + for (auto const& item: table) { + auto o = item.offset(); + if (start < o && o <= offset) { + start = o; + id = i; + gen = item.gen(); + } + ++i; + } + return QPDFObjGen(id, gen); +} + +std::map +Xref_table::as_map() const +{ + std::map result; + int i{0}; + for (auto const& item: table) { + switch (item.type()) { + case 0: + break; + case 1: + result.emplace(QPDFObjGen(i, item.gen()), item.offset()); + break; + case 2: + result.emplace( + QPDFObjGen(i, 0), QPDFXRefEntry(item.stream_number(), item.stream_index())); + break; + default: + throw std::logic_error("Xref_table: invalid entry type"); + } + ++i; + } + return result; +} + +void +Xref_table::show() +{ + auto& cout = *qpdf.m->log->getInfo(); + int i = -1; + for (auto const& item: table) { + ++i; + if (item.type()) { + cout << std::to_string(i) << "/" << std::to_string(item.gen()) << ": "; + switch (item.type()) { + case 1: + cout << "uncompressed; offset = " << item.offset() << "\n"; + break; + + case 2: + cout << "compressed; stream = " << item.stream_number() + << ", index = " << item.stream_index() << "\n"; + break; + + default: + throw std::logic_error( + "unknown cross-reference table type while showing xref_table"); + } + } + } +} + +// Resolve all objects in the xref table. If this triggers a xref table reconstruction abort and +// return false. Otherwise return true. +bool +Xref_table::resolve() +{ + bool may_change = !reconstructed_; + int i = -1; + for (auto& item: table) { + ++i; + if (item.type()) { + if (objects.unresolved(QPDFObjGen(i, item.gen()))) { + objects.resolve(QPDFObjGen(i, item.gen())); + if (may_change && reconstructed_) { + return false; + } + } + } + } + return true; +} + +std::vector +Objects ::all() +{ + // After fixDanglingReferences is called, all objects are in the object cache. + qpdf.fixDanglingReferences(); + std::vector result; + for (auto const& iter: table) { + result.emplace_back(iter.second.object); + } + return result; +} + +QPDFObjectHandle +Xref_table::read_trailer() +{ + qpdf_offset_t offset = file->tell(); + bool empty = false; + auto object = QPDFParser(*file, "trailer", tokenizer, nullptr, &qpdf, true).parse(empty, false); + if (empty) { + // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in + // actual PDF files and Adobe Reader appears to ignore them. + qpdf.warn(qpdf.damagedPDF("trailer", "empty object treated as null")); + } else if (object.isDictionary() && read_token().isWord("stream")) { + qpdf.warn(qpdf.damagedPDF("trailer", file->tell(), "stream keyword found in trailer")); + } + // Override last_offset so that it points to the beginning of the object we just read + file->setLastOffset(offset); + return object; +} + +QPDFObjectHandle +Objects::read_object(std::string const& description, QPDFObjGen og) +{ + qpdf.setLastObjectDescription(description, og); + qpdf_offset_t offset = m->file->tell(); + bool empty = false; + + StringDecrypter decrypter{&qpdf, og}; + StringDecrypter* decrypter_ptr = m->encp->encrypted ? &decrypter : nullptr; + auto object = + QPDFParser(*m->file, m->last_object_description, m->tokenizer, decrypter_ptr, &qpdf, true) + .parse(empty, false); + if (empty) { + // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in + // actual PDF files and Adobe Reader appears to ignore them. + qpdf.warn( + qpdf.damagedPDF(*m->file, m->file->getLastOffset(), "empty object treated as null")); + return object; + } + auto token = qpdf.readToken(*m->file); + if (object.isDictionary() && token.isWord("stream")) { + read_stream(object, og, offset); + token = qpdf.readToken(*m->file); + } + if (!token.isWord("endobj")) { + QTC::TC("qpdf", "QPDF err expected endobj"); + qpdf.warn(qpdf.damagedPDF("expected endobj")); + } + return object; +} + +// After reading stream dictionary and stream keyword, read rest of stream. +void +Objects::read_stream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset) +{ + validate_stream_line_end(object, og, offset); + + // Must get offset before accessing any additional objects since resolving a previously + // unresolved indirect object will change file position. + qpdf_offset_t stream_offset = m->file->tell(); + size_t length = 0; + + try { + auto length_obj = object.getKey("/Length"); + + if (!length_obj.isInteger()) { + if (length_obj.isNull()) { + QTC::TC("qpdf", "QPDF stream without length"); + throw qpdf.damagedPDF(offset, "stream dictionary lacks /Length key"); + } + QTC::TC("qpdf", "QPDF stream length not integer"); + throw qpdf.damagedPDF(offset, "/Length key in stream dictionary is not an integer"); + } + + length = toS(length_obj.getUIntValue()); + // Seek in two steps to avoid potential integer overflow + m->file->seek(stream_offset, SEEK_SET); + m->file->seek(toO(length), SEEK_CUR); + if (!qpdf.readToken(*m->file).isWord("endstream")) { + QTC::TC("qpdf", "QPDF missing endstream"); + throw qpdf.damagedPDF("expected endstream"); + } + } catch (QPDFExc& e) { + if (m->attempt_recovery) { + qpdf.warn(e); + length = recover_stream_length(m->file_sp, og, stream_offset); + } else { + throw; + } + } + object = {QPDF_Stream::create(&qpdf, og, object, stream_offset, length)}; +} + +void +Objects::validate_stream_line_end(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset) +{ + // The PDF specification states that the word "stream" should be followed by either a carriage + // return and a newline or by a newline alone. It specifically disallowed following it by a + // carriage return alone since, in that case, there would be no way to tell whether the NL in a + // CR NL sequence was part of the stream data. However, some readers, including Adobe reader, + // accept a carriage return by itself when followed by a non-newline character, so that's what + // we do here. We have also seen files that have extraneous whitespace between the stream + // keyword and the newline. + while (true) { + char ch; + if (m->file->read(&ch, 1) == 0) { + // A premature EOF here will result in some other problem that will get reported at + // another time. + return; + } + if (ch == '\n') { + // ready to read stream data + QTC::TC("qpdf", "QPDF stream with NL only"); + return; + } + if (ch == '\r') { + // Read another character + if (m->file->read(&ch, 1) != 0) { + if (ch == '\n') { + // Ready to read stream data + QTC::TC("qpdf", "QPDF stream with CRNL"); + } else { + // Treat the \r by itself as the whitespace after endstream and start reading + // stream data in spite of not having seen a newline. + QTC::TC("qpdf", "QPDF stream with CR only"); + m->file->unreadCh(ch); + qpdf.warn(qpdf.damagedPDF( + m->file->tell(), "stream keyword followed by carriage return only")); + } + } + return; + } + if (!QUtil::is_space(ch)) { + QTC::TC("qpdf", "QPDF stream without newline"); + m->file->unreadCh(ch); + qpdf.warn(qpdf.damagedPDF( + m->file->tell(), "stream keyword not followed by proper line terminator")); + return; + } + qpdf.warn( + qpdf.damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace")); + } +} + +QPDFObjectHandle +Objects::readObjectInStream(std::shared_ptr& input, int obj) +{ + m->last_object_description.erase(7); // last_object_description starts with "object " + m->last_object_description += std::to_string(obj); + m->last_object_description += " 0"; + + bool empty = false; + auto object = QPDFParser(*input, m->last_object_description, m->tokenizer, nullptr, &qpdf, true) + .parse(empty, false); + if (empty) { + // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in + // actual PDF files and Adobe Reader appears to ignore them. + qpdf.warn(qpdf.damagedPDF(*input, input->getLastOffset(), "empty object treated as null")); + } + return object; +} + +bool +QPDF::findEndstream() +{ + // Find endstream or endobj. Position the input at that token. + auto t = readToken(*m->file, 20); + if (t.isWord("endobj") || t.isWord("endstream")) { + m->file->seek(m->file->getLastOffset(), SEEK_SET); + return true; + } + return false; +} + +size_t +Objects::recover_stream_length( + std::shared_ptr input, QPDFObjGen og, qpdf_offset_t stream_offset) +{ + // Try to reconstruct stream length by looking for endstream or endobj + qpdf.warn(qpdf.damagedPDF(*input, stream_offset, "attempting to recover stream length")); + + PatternFinder ef(qpdf, &QPDF::findEndstream); + size_t length = 0; + if (m->file->findFirst("end", stream_offset, 0, ef)) { + length = toS(m->file->tell() - stream_offset); + // Reread endstream but, if it was endobj, don't skip that. + QPDFTokenizer::Token t = qpdf.readToken(*m->file); + if (t.getValue() == "endobj") { + m->file->seek(m->file->getLastOffset(), SEEK_SET); + } + } + + if (length) { + // Make sure this is inside this object + auto found = xref.at_offset(stream_offset + toO(length)); + if (found == QPDFObjGen() || found == og) { + // If we are trying to recover an XRef stream the xref table will not contain and + // won't contain any entries, therefore we cannot check the found length. Otherwise we + // found endstream\endobj within the space allowed for this object, so we're probably + // in good shape. + } else { + QTC::TC("qpdf", "QPDF found wrong endstream in recovery"); + length = 0; + } + } + + if (length == 0) { + qpdf.warn(qpdf.damagedPDF( + *input, stream_offset, "unable to recover stream data; treating stream as empty")); + } else { + qpdf.warn(qpdf.damagedPDF( + *input, stream_offset, "recovered stream length: " + std::to_string(length))); + } + + QTC::TC("qpdf", "QPDF recovered stream length"); + return length; +} + +QPDFObjectHandle +Objects::read( + bool try_recovery, + qpdf_offset_t offset, + std::string const& description, + QPDFObjGen exp_og, + QPDFObjGen& og, + bool skip_cache_if_in_xref) +{ + bool check_og = true; + if (exp_og.getObj() == 0) { + // This method uses an expect object ID of 0 to indicate that we don't know or don't care + // what the actual object ID is at this offset. This is true when we read the xref stream + // and linearization hint streams. In this case, we don't verify the expect object + // ID/generation against what was read from the file. There is also no reason to attempt + // xref recovery if we get a failure in this case since the read attempt was not triggered + // by an xref lookup. + check_og = false; + try_recovery = false; + } + qpdf.setLastObjectDescription(description, exp_og); + + if (!m->attempt_recovery) { + try_recovery = false; + } + + // Special case: if offset is 0, just return null. Some PDF writers, in particular + // "Mac OS X 10.7.5 Quartz PDFContext", may store deleted objects in the xref table as + // "0000000000 00000 n", which is not correct, but it won't hurt anything for us to ignore + // these. + if (offset == 0) { + QTC::TC("qpdf", "QPDF bogus 0 offset", 0); + qpdf.warn(qpdf.damagedPDF(0, "object has offset 0")); + return QPDFObjectHandle::newNull(); + } + + m->file->seek(offset, SEEK_SET); + try { + QPDFTokenizer::Token tobjid = qpdf.readToken(*m->file); + bool objidok = tobjid.isInteger(); + QTC::TC("qpdf", "QPDF check objid", objidok ? 1 : 0); + if (!objidok) { + QTC::TC("qpdf", "QPDF expected n n obj"); + throw qpdf.damagedPDF(offset, "expected n n obj"); + } + QPDFTokenizer::Token tgen = qpdf.readToken(*m->file); + bool genok = tgen.isInteger(); + QTC::TC("qpdf", "QPDF check generation", genok ? 1 : 0); + if (!genok) { + throw qpdf.damagedPDF(offset, "expected n n obj"); + } + QPDFTokenizer::Token tobj = qpdf.readToken(*m->file); + + bool objok = tobj.isWord("obj"); + QTC::TC("qpdf", "QPDF check obj", objok ? 1 : 0); + + if (!objok) { + throw qpdf.damagedPDF(offset, "expected n n obj"); + } + int objid = QUtil::string_to_int(tobjid.getValue().c_str()); + int generation = QUtil::string_to_int(tgen.getValue().c_str()); + og = QPDFObjGen(objid, generation); + if (objid == 0) { + QTC::TC("qpdf", "QPDF object id 0"); + throw qpdf.damagedPDF(offset, "object with ID 0"); + } + if (check_og && (exp_og != og)) { + QTC::TC("qpdf", "QPDF err wrong objid/generation"); + QPDFExc e = qpdf.damagedPDF(offset, "expected " + exp_og.unparse(' ') + " obj"); + if (try_recovery) { + // Will be retried below + throw e; + } else { + // We can try reading the object anyway even if the ID doesn't match. + qpdf.warn(e); + } + } + } catch (QPDFExc& e) { + if (try_recovery) { + // Try again after reconstructing xref table + xref.reconstruct(e); + if (xref.type(exp_og) == 1) { + QTC::TC("qpdf", "QPDF recovered in readObjectAtOffset"); + return read(false, xref.offset(exp_og), description, exp_og, og, false); + } else { + QTC::TC("qpdf", "QPDF object gone after xref reconstruction"); + qpdf.warn(qpdf.damagedPDF( + "", + 0, + ("object " + exp_og.unparse(' ') + + " not found in file after regenerating cross reference table"))); + return QPDFObjectHandle::newNull(); + } + } else { + throw; + } + } + + QPDFObjectHandle oh = read_object(description, og); + + if (unresolved(og)) { + // Store the object in the cache here so it gets cached whether we first know the offset or + // whether we first know the object ID and generation (in which we case we would get here + // through resolve). + + // Determine the end offset of this object before and after white space. We use these + // numbers to validate linearization hint tables. Offsets and lengths of objects may imply + // the end of an object to be anywhere between these values. + qpdf_offset_t end_before_space = m->file->tell(); + + // skip over spaces + while (true) { + char ch; + if (m->file->read(&ch, 1)) { + if (!isspace(static_cast(ch))) { + m->file->seek(-1, SEEK_CUR); + break; + } + } else { + throw qpdf.damagedPDF(m->file->tell(), "EOF after endobj"); + } + } + qpdf_offset_t end_after_space = m->file->tell(); + if (skip_cache_if_in_xref && xref.type(og)) { + // Ordinarily, an object gets read here when resolved through xref table or stream. In + // the special case of the xref stream and linearization hint tables, the offset comes + // from another source. For the specific case of xref streams, the xref stream is read + // and loaded into the object cache very early in parsing. Ordinarily, when a file is + // updated by appending, items inserted into the xref table in later updates take + // precedence over earlier items. In the special case of reusing the object number + // previously used as the xref stream, we have the following order of events: + // + // * reused object gets loaded into the xref table + // * old object is read here while reading xref streams + // * original xref entry is ignored (since already in xref table) + // + // It is the second step that causes a problem. Even though the xref table is correct in + // this case, the old object is already in the cache and so effectively prevails over + // the reused object. To work around this issue, we have a special case for the xref + // stream (via the skip_cache_if_in_xref): if the object is already in the xref stream, + // don't cache what we read here. + // + // It is likely that the same bug may exist for linearization hint tables, but the + // existing code uses end_before_space and end_after_space from the cache, so fixing + // that would require more significant rework. The chances of a linearization hint + // stream being reused seems smaller because the xref stream is probably the highest + // object in the file and the linearization hint stream would be some random place in + // the middle, so I'm leaving that bug unfixed for now. If the bug were to be fixed, we + // could use !check_og in place of skip_cache_if_in_xref. + QTC::TC("qpdf", "QPDF skipping cache for known unchecked object"); + } else { + xref.linearization_offsets(toS(og.getObj()), end_before_space, end_after_space); + update_table(og, oh.getObj()); + } + } + + return oh; +} + +QPDFObject* +Objects::resolve(QPDFObjGen og) +{ + if (!unresolved(og)) { + return table[og].object.get(); + } + + if (m->resolving.count(og)) { + // This can happen if an object references itself directly or indirectly in some key that + // has to be resolved during object parsing, such as stream length. + QTC::TC("qpdf", "QPDF recursion loop in resolve"); + qpdf.warn(qpdf.damagedPDF("", "loop detected resolving object " + og.unparse(' '))); + update_table(og, QPDF_Null::create()); + return table[og].object.get(); + } + ResolveRecorder rr(&qpdf, og); + + try { + switch (xref.type(og)) { + case 0: + break; + case 1: + { + // Object stored in cache by readObjectAtOffset + QPDFObjGen a_og; + QPDFObjectHandle oh = read(true, xref.offset(og), "", og, a_og, false); + } + break; + + case 2: + resolveObjectsInStream(xref.stream_number(og.getObj())); + break; + + default: + throw qpdf.damagedPDF( + "", 0, ("object " + og.unparse('/') + " has unexpected xref entry type")); + } + } catch (QPDFExc& e) { + qpdf.warn(e); + } catch (std::exception& e) { + qpdf.warn(qpdf.damagedPDF( + "", 0, ("object " + og.unparse('/') + ": error reading object: " + e.what()))); + } + + if (unresolved(og)) { + // PDF spec says unknown objects resolve to the null object. + QTC::TC("qpdf", "QPDF resolve failure to null"); + update_table(og, QPDF_Null::create()); + } + + auto result(table[og].object); + result->setDefaultDescription(&qpdf, og); + return result.get(); +} + +void +Objects::resolveObjectsInStream(int obj_stream_number) +{ + if (m->resolved_object_streams.count(obj_stream_number)) { + return; + } + m->resolved_object_streams.insert(obj_stream_number); + // Force resolution of object stream + QPDFObjectHandle obj_stream = get(obj_stream_number, 0); + if (!obj_stream.isStream()) { + throw qpdf.damagedPDF( + "supposed object stream " + std::to_string(obj_stream_number) + " is not a stream"); + } + + QPDFObjectHandle dict = obj_stream.getDict(); + if (!dict.isDictionaryOfType("/ObjStm")) { + QTC::TC("qpdf", "QPDF ERR object stream with wrong type"); + qpdf.warn(qpdf.damagedPDF( + "supposed object stream " + std::to_string(obj_stream_number) + " has wrong type")); + } + + if (!(dict.getKey("/N").isInteger() && dict.getKey("/First").isInteger())) { + throw qpdf.damagedPDF( + ("object stream " + std::to_string(obj_stream_number) + " has incorrect keys")); + } + + int n = dict.getKey("/N").getIntValueAsInt(); + int first = dict.getKey("/First").getIntValueAsInt(); + + std::map offsets; + + std::shared_ptr bp = obj_stream.getStreamData(qpdf_dl_specialized); + auto input = std::shared_ptr( + // line-break + new BufferInputSource( + (m->file->getName() + " object stream " + std::to_string(obj_stream_number)), + bp.get())); + + qpdf_offset_t last_offset = -1; + for (int i = 0; i < n; ++i) { + QPDFTokenizer::Token tnum = qpdf.readToken(*input); + QPDFTokenizer::Token toffset = qpdf.readToken(*input); + if (!(tnum.isInteger() && toffset.isInteger())) { + throw damagedPDF( + *input, + m->last_object_description, + input->getLastOffset(), + "expected integer in object stream header"); + } + + int num = QUtil::string_to_int(tnum.getValue().c_str()); + long long offset = QUtil::string_to_int(toffset.getValue().c_str()); + if (num > xref.max_id()) { + continue; + } + if (num == obj_stream_number) { + QTC::TC("qpdf", "QPDF ignore self-referential object stream"); + qpdf.warn(damagedPDF( + *input, + m->last_object_description, + input->getLastOffset(), + "object stream claims to contain itself")); + continue; + } + if (offset <= last_offset) { + throw damagedPDF( + *input, + m->last_object_description, + input->getLastOffset(), + "expected offsets in object stream to be increasing"); + } + last_offset = offset; + + offsets[num] = toI(offset + first); + } + + // To avoid having to read the object stream multiple times, store all objects that would be + // found here in the cache. Remember that some objects stored here might have been overridden + // by new objects appended to the file, so it is necessary to recheck the xref table and only + // cache what would actually be resolved here. + m->last_object_description.clear(); + m->last_object_description += "object "; + for (auto const& iter: offsets) { + QPDFObjGen og(iter.first, 0); + if (xref.type(og) == 2 && xref.stream_number(og.getObj()) == obj_stream_number) { + int offset = iter.second; + input->seek(offset, SEEK_SET); + QPDFObjectHandle oh = readObjectInStream(input, iter.first); + update_table(og, oh.getObj()); + } else { + QTC::TC("qpdf", "QPDF not caching overridden objstm object"); + } + } +} + +Objects::~Objects() +{ + // If two objects are mutually referential (through each object having an array or dictionary + // that contains an indirect reference to the other), the circular references in the + // std::shared_ptr objects will prevent the objects from being deleted. Walk through all objects + // in the object cache, which is those objects that we read from the file, and break all + // resolved indirect references by replacing them with an internal object type representing that + // they have been destroyed. Note that we can't break references like this at any time when the + // QPDF object is active. The call to reset also causes all direct QPDFObjectHandle objects that + // are reachable from this object to release their association with this QPDF. Direct objects + // are not destroyed since they can be moved to other QPDF objects safely. + + for (auto const& iter: table) { + iter.second.object->disconnect(); + if (iter.second.object->getTypeCode() != ::ot_null) { + iter.second.object->destroy(); + } + } +} + +void +Objects::update_table(QPDFObjGen og, const std::shared_ptr& object) +{ + object->setObjGen(&qpdf, og); + if (cached(og)) { + auto& cache = table[og]; + cache.object->assign(object); + } else { + table[og] = Entry(object); + } +} + +bool +Objects::cached(QPDFObjGen og) +{ + return table.count(og) != 0; +} + +bool +Objects::unresolved(QPDFObjGen og) +{ + return !cached(og) || table[og].object->isUnresolved(); +} + +QPDFObjGen +Objects::next_id() +{ + qpdf.fixDanglingReferences(); + QPDFObjGen og; + if (!table.empty()) { + og = (*(m->objects.table.rbegin())).first; + } + int max_objid = og.getObj(); + if (max_objid == std::numeric_limits::max()) { + throw std::range_error("max object id is too high to create new objects"); + } + return QPDFObjGen(max_objid + 1, 0); +} + +QPDFObjectHandle +Objects::make_indirect(std::shared_ptr const& obj) +{ + QPDFObjGen next{next_id()}; + table[next] = Entry(obj); + return qpdf.newIndirect(next, table[next].object); +} + +std::shared_ptr +Objects::get_for_parser(int id, int gen, bool parse_pdf) +{ + // This method is called by the parser and therefore must not resolve any objects. + auto og = QPDFObjGen(id, gen); + if (auto iter = table.find(og); iter != table.end()) { + return iter->second.object; + } + if (xref.type(og) || !xref.initialized()) { + return table.insert({og, QPDF_Unresolved::create(&qpdf, og)}).first->second.object; + } + if (parse_pdf) { + return QPDF_Null::create(); + } + return table.insert({og, QPDF_Null::create(&qpdf, og)}).first->second.object; +} + +std::shared_ptr +Objects::get_for_json(int id, int gen) +{ + auto og = QPDFObjGen(id, gen); + auto [it, inserted] = table.try_emplace(og); + auto& obj = it->second.object; + if (inserted) { + obj = (xref.initialized() && !xref.type(og)) ? QPDF_Null::create(&qpdf, og) + : QPDF_Unresolved::create(&qpdf, og); + } + return obj; +} + +void +Objects::replace(QPDFObjGen og, QPDFObjectHandle oh) +{ + if (!oh || (oh.isIndirect() && !(oh.isStream() && oh.getObjGen() == og))) { + QTC::TC("qpdf", "QPDF replaceObject called with indirect object"); + throw std::logic_error("QPDF::replaceObject called with indirect object handle"); + } + update_table(og, oh.getObj()); +} + +void +Objects::erase(QPDFObjGen og) +{ + if (auto cached = table.find(og); cached != table.end()) { + // Take care of any object handles that may be floating around. + cached->second.object->assign(QPDF_Null::create()); + cached->second.object->setObjGen(nullptr, QPDFObjGen()); + table.erase(cached); + } +} + +void +Objects::swap(QPDFObjGen og1, QPDFObjGen og2) +{ + // Force objects to be read from the input source if needed, then swap them in the cache. + resolve(og1); + resolve(og2); + table[og1].object->swapWith(table[og2].object); +} + +size_t +Objects::table_size() +{ + // If table is dense, accommodate all object in tables,else accommodate only original + // objects. + auto max_xref = toI(xref.size()); + if (max_xref > 0) { + --max_xref; + } + auto max_obj = table.size() ? table.crbegin()->first.getObj() : 0; + auto max_id = std::numeric_limits::max() - 1; + if (max_obj >= max_id || max_xref >= max_id) { + // Temporary fix. Long-term solution is + // - QPDFObjGen to enforce objgens are valid and sensible + // - xref table and obj cache to protect against insertion of impossibly large obj ids + qpdf.stopOnError("Impossibly large object id encountered."); + } + if (max_obj < 1.1 * std::max(toI(table.size()), max_xref)) { + return toS(++max_obj); + } + return toS(++max_xref); +} + +std::vector +Objects::compressible_vector() +{ + return compressible(); +} + +std::vector +Objects::compressible_set() +{ + return compressible(); +} + +template +std::vector +Objects::compressible() +{ + // Return a list of objects that are allowed to be in object streams. Walk through the objects + // by traversing the document from the root, including a traversal of the pages tree. This + // makes that objects that are on the same page are more likely to be in the same object stream, + // which is slightly more efficient, particularly with linearized files. This is better than + // iterating through the xref table since it avoids preserving orphaned items. + + // Exclude encryption dictionary, if any + QPDFObjectHandle encryption_dict = trailer().getKey("/Encrypt"); + QPDFObjGen encryption_dict_og = encryption_dict.getObjGen(); + + const size_t max_obj = qpdf.getObjectCount(); + std::vector visited(max_obj, false); + std::vector queue; + queue.reserve(512); + queue.emplace_back(trailer()); + std::vector result; + if constexpr (std::is_same_v) { + result.reserve(table.size()); + } else if constexpr (std::is_same_v) { + result.resize(max_obj + 1U, false); + } else { + throw std::logic_error("Unsupported type in QPDF::getCompressibleObjGens"); + } + while (!queue.empty()) { + auto obj = queue.back(); + queue.pop_back(); + if (obj.getObjectID() > 0) { + QPDFObjGen og = obj.getObjGen(); + const size_t id = toS(og.getObj() - 1); + if (id >= max_obj) { + throw std::logic_error( + "unexpected object id encountered in getCompressibleObjGens"); + } + if (visited[id]) { + QTC::TC("qpdf", "QPDF loop detected traversing objects"); + continue; + } + + // Check whether this is the current object. If not, remove it (which changes it into a + // direct null and therefore stops us from revisiting it) and move on to the next object + // in the queue. + auto upper = table.upper_bound(og); + if (upper != table.end() && upper->first.getObj() == og.getObj()) { + erase(og); + continue; + } + + visited[id] = true; + + if (og == encryption_dict_og) { + QTC::TC("qpdf", "QPDF exclude encryption dictionary"); + } else if (!(obj.isStream() || + (obj.isDictionaryOfType("/Sig") && obj.hasKey("/ByteRange") && + obj.hasKey("/Contents")))) { + if constexpr (std::is_same_v) { + result.push_back(og); + } else if constexpr (std::is_same_v) { + result[id + 1U] = true; + } + } + } + if (obj.isStream()) { + QPDFObjectHandle dict = obj.getDict(); + std::set keys = dict.getKeys(); + for (auto iter = keys.rbegin(); iter != keys.rend(); ++iter) { + std::string const& key = *iter; + QPDFObjectHandle value = dict.getKey(key); + if (key == "/Length") { + // omit stream lengths + if (value.isIndirect()) { + QTC::TC("qpdf", "QPDF exclude indirect length"); + } + } else { + queue.push_back(value); + } + } + } else if (obj.isDictionary()) { + std::set keys = obj.getKeys(); + for (auto iter = keys.rbegin(); iter != keys.rend(); ++iter) { + queue.push_back(obj.getKey(*iter)); + } + } else if (obj.isArray()) { + int n = obj.getArrayNItems(); + for (int i = 1; i <= n; ++i) { + queue.push_back(obj.getArrayItem(n - i)); + } + } + } + + return result; +} diff --git a/libqpdf/QPDF_optimization.cc b/libqpdf/QPDF_optimization.cc index 3dcaa360..585b7075 100644 --- a/libqpdf/QPDF_optimization.cc +++ b/libqpdf/QPDF_optimization.cc @@ -79,9 +79,9 @@ QPDF::optimize( } void -QPDF::optimize(QPDF::Xref_table const& xref) +QPDF::optimize(QPDF::Objects const& objects) { - optimize_internal(xref, false, nullptr); + optimize_internal(objects, false, nullptr); } template @@ -121,13 +121,13 @@ QPDF::optimize_internal( } // Traverse document-level items - for (auto const& key: m->xref_table.trailer().getKeys()) { + for (auto const& key: m->objects.trailer().getKeys()) { if (key == "/Root") { // handled separately } else { updateObjectMaps( ObjUser(ObjUser::ou_trailer_key, key), - m->xref_table.trailer().getKey(key), + m->objects.trailer().getKey(key), skip_stream_parameters); } } @@ -175,7 +175,7 @@ QPDF::pushInheritedAttributesToPage(bool allow_changes, bool warn_skipped_keys) // values for them. std::map> key_ancestors; pushInheritedAttributesToPageInternal( - m->xref_table.trailer().getKey("/Root").getKey("/Pages"), + m->objects.trailer().getKey("/Root").getKey("/Pages"), key_ancestors, allow_changes, warn_skipped_keys); @@ -450,8 +450,9 @@ QPDF::filterCompressedObjects(QPDFWriter::ObjTable const& obj) } void -QPDF::filterCompressedObjects(QPDF::Xref_table const& xref) +QPDF::filterCompressedObjects(QPDF::Objects const& objects) { + auto const& xref = objects.xref_table(); if (!xref.object_streams()) { return; } diff --git a/libqpdf/qpdf-c.cc b/libqpdf/qpdf-c.cc index a4912186..0fb582ad 100644 --- a/libqpdf/qpdf-c.cc +++ b/libqpdf/qpdf-c.cc @@ -905,7 +905,7 @@ qpdf_oh qpdf_get_object_by_id(qpdf_data qpdf, int objid, int generation) { QTC::TC("qpdf", "qpdf-c called qpdf_get_object_by_id"); - return new_object(qpdf, qpdf->qpdf->getObjectByID(objid, generation)); + return new_object(qpdf, qpdf->qpdf->getObject(objid, generation)); } template diff --git a/libqpdf/qpdf/QPDF_objects.hh b/libqpdf/qpdf/QPDF_objects.hh new file mode 100644 index 00000000..83b74800 --- /dev/null +++ b/libqpdf/qpdf/QPDF_objects.hh @@ -0,0 +1,497 @@ +#ifndef QPDF_OBJECTS_HH +#define QPDF_OBJECTS_HH + +#include + +#include +#include + +#include + +// The Objects class is responsible for keeping track of all objects belonging to a QPDF instance, +// including loading it from an input source when required. +class QPDF::Objects +{ + public: + // Xref_table encapsulates the pdf's xref table and trailer. + class Xref_table + { + public: + Xref_table(Objects& objects) : + qpdf(objects.qpdf), + objects(objects), + file(objects.file) + { + tokenizer.allowEOF(); + } + + void initialize(); + void initialize_empty(); + void initialize_json(); + void reconstruct(QPDFExc& e); + void show(); + bool resolve(); + + QPDFObjectHandle + trailer() noexcept + { + return trailer_; + } + + QPDFObjectHandle const& + trailer() const noexcept + { + return trailer_; + } + + void + trailer(QPDFObjectHandle&& oh) + { + trailer_ = std::move(oh); + } + + // Returns 0 if og is not in table. + size_t + type(QPDFObjGen og) const + { + int id = og.getObj(); + if (id < 1 || static_cast(id) >= table.size()) { + return 0; + } + auto& e = table[static_cast(id)]; + return e.gen() == og.getGen() ? e.type() : 0; + } + + // Returns 0 if og is not in table. + size_t + type(size_t id) const noexcept + { + if (id >= table.size()) { + return 0; + } + return table[id].type(); + } + + // Returns 0 if og is not in table. + qpdf_offset_t + offset(QPDFObjGen og) const noexcept + { + int id = og.getObj(); + if (id < 1 || static_cast(id) >= table.size()) { + return 0; + } + return table[static_cast(id)].offset(); + } + + // Returns 0 if id is not in table. + int + stream_number(int id) const noexcept + { + if (id < 1 || static_cast(id) >= table.size()) { + return 0; + } + return table[static_cast(id)].stream_number(); + } + + int + stream_index(int id) const noexcept + { + if (id < 1 || static_cast(id) >= table.size()) { + return 0; + } + return table[static_cast(id)].stream_index(); + } + + QPDFObjGen at_offset(qpdf_offset_t offset) const noexcept; + + std::map as_map() const; + + bool + object_streams() const noexcept + { + return object_streams_; + } + + // Return a vector of object id and stream number for each compressed object. + std::vector> + compressed_objects() const + { + if (!initialized()) { + throw std::logic_error("Xref_table::compressed_objects called before parsing."); + } + + std::vector> result; + result.reserve(table.size()); + + unsigned int i{0}; + for (auto const& item: table) { + if (item.type() == 2) { + result.emplace_back(i, item.stream_number()); + } + ++i; + } + return result; + } + + // Temporary access to underlying table size + size_t + size() const noexcept + { + return table.size(); + } + + void + ignore_streams(bool val) noexcept + { + ignore_streams_ = val; + } + + bool + initialized() const noexcept + { + return initialized_; + } + + void + attempt_recovery(bool val) noexcept + { + attempt_recovery_ = val; + } + + int + max_id() const noexcept + { + return max_id_; + } + + // For Linearization + + qpdf_offset_t + end_after_space(QPDFObjGen og) + { + auto& e = entry(toS(og.getObj())); + switch (e.type()) { + case 1: + return e.end_after_space_; + case 2: + { + auto es = entry(toS(e.stream_number())); + return es.type() == 1 ? es.end_after_space_ : 0; + } + default: + return 0; + } + } + + qpdf_offset_t + end_before_space(QPDFObjGen og) + { + auto& e = entry(toS(og.getObj())); + switch (e.type()) { + case 1: + return e.end_before_space_; + case 2: + { + auto es = entry(toS(e.stream_number())); + return es.type() == 1 ? es.end_before_space_ : 0; + } + default: + return 0; + } + } + + void + linearization_offsets(size_t id, qpdf_offset_t before, qpdf_offset_t after) + { + if (type(id)) { + table[id].end_before_space_ = before; + table[id].end_after_space_ = after; + } + } + + bool + uncompressed_after_compressed() const noexcept + { + return uncompressed_after_compressed_; + } + + // Actual value from file + qpdf_offset_t + first_item_offset() const noexcept + { + return first_item_offset_; + } + + private: + // Object, count, offset of first entry + typedef std::tuple Subsection; + + struct Uncompressed + { + Uncompressed(qpdf_offset_t offset) : + offset(offset) + { + } + qpdf_offset_t offset; + }; + + struct Compressed + { + Compressed(int stream_number, int stream_index) : + stream_number(stream_number), + stream_index(stream_index) + { + } + int stream_number{0}; + int stream_index{0}; + }; + + typedef std::variant Xref; + + struct Entry + { + Entry() = default; + + Entry(int gen, Xref entry) : + gen_(gen), + entry(entry) + { + } + + int + gen() const noexcept + { + return gen_; + } + + size_t + type() const noexcept + { + return entry.index(); + } + + qpdf_offset_t + offset() const noexcept + { + return type() == 1 ? std::get<1>(entry).offset : 0; + } + + int + stream_number() const noexcept + { + return type() == 2 ? std::get<2>(entry).stream_number : 0; + } + + int + stream_index() const noexcept + { + return type() == 2 ? std::get<2>(entry).stream_index : 0; + } + + int gen_{0}; + Xref entry; + qpdf_offset_t end_before_space_{0}; + qpdf_offset_t end_after_space_{0}; + }; + + Entry& + entry(size_t id) + { + return id < table.size() ? table[id] : table[0]; + } + + void read(qpdf_offset_t offset); + + // Methods to parse tables + qpdf_offset_t process_section(qpdf_offset_t offset); + std::vector subsections(std::string& line); + std::vector bad_subsections(std::string& line, qpdf_offset_t offset); + Subsection subsection(std::string const& line); + std::tuple read_entry(); + std::tuple read_bad_entry(); + + // Methods to parse streams + qpdf_offset_t read_stream(qpdf_offset_t offset); + qpdf_offset_t process_stream(qpdf_offset_t offset, QPDFObjectHandle& xref_stream); + std::pair> + process_W(QPDFObjectHandle& dict, std::function damaged); + std::pair process_Size( + QPDFObjectHandle& dict, + int entry_size, + std::function damaged); + std::pair>> process_Index( + QPDFObjectHandle& dict, + int max_num_entries, + std::function damaged); + + QPDFObjectHandle read_trailer(); + + QPDFTokenizer::Token + read_token(size_t max_len = 0) + { + return tokenizer.readToken(*file, "", true, max_len); + } + + // Methods to insert table entries + void insert(int obj, int f0, qpdf_offset_t f1, int f2); + void insert_free(QPDFObjGen); + + QPDFExc + damaged_pdf(std::string const& msg) + { + return qpdf.damagedPDF("", 0, msg); + } + + QPDFExc + damaged_table(std::string const& msg) + { + return qpdf.damagedPDF("xref table", msg); + } + + void + warn_damaged(std::string const& msg) + { + qpdf.warn(damaged_pdf(msg)); + } + + QPDF& qpdf; + QPDF::Objects& objects; + InputSource* const& file; + QPDFTokenizer tokenizer; + + std::vector table; + QPDFObjectHandle trailer_; + + bool attempt_recovery_{true}; + bool initialized_{false}; + bool ignore_streams_{false}; + bool reconstructed_{false}; + bool object_streams_{false}; + // Before the xref table is initialized, max_id_ is an upper bound on the possible object + // ids that could be present in the PDF file. Once the trailer has been read, max_id_ is set + // to the value of /Size. If the file is damaged, max_id_ becomes the maximum object id in + // the xref table after reconstruction. + int max_id_{std::numeric_limits::max() - 1}; + + // Linearization data + bool uncompressed_after_compressed_{false}; + qpdf_offset_t first_item_offset_{0}; // actual value from file + }; // Xref_table; + + ~Objects(); + + Objects(QPDF& qpdf, QPDF::Members* m, InputSource* const& file) : + qpdf(qpdf), + file(file), + m(m), + xref(*this) + { + } + + Xref_table& + xref_table() noexcept + { + return xref; + } + + Xref_table const& + xref_table() const noexcept + { + return xref; + } + + QPDFObjectHandle + trailer() noexcept + { + return xref.trailer(); + } + + QPDFObjectHandle const& + trailer() const noexcept + { + return xref.trailer(); + } + + QPDFObjectHandle + get(QPDFObjGen og) + { + if (auto it = table.find(og); it != table.end()) { + return {it->second.object}; + } else if (xref.initialized() && !xref.type(og)) { + return QPDF_Null::create(); + } else { + auto result = table.try_emplace(og, QPDF_Unresolved::create(&qpdf, og)); + return {result.first->second.object}; + } + } + + QPDFObjectHandle + get(int id, int gen) + { + return get(QPDFObjGen(id, gen)); + } + + std::vector all(); + + void erase(QPDFObjGen og); + + void replace(QPDFObjGen og, QPDFObjectHandle oh); + + void swap(QPDFObjGen og1, QPDFObjGen og2); + + QPDFObjectHandle read( + bool attempt_recovery, + qpdf_offset_t offset, + std::string const& description, + QPDFObjGen exp_og, + QPDFObjGen& og, + bool skip_cache_if_in_xref); + QPDFObject* resolve(QPDFObjGen og); + void update_table(QPDFObjGen og, std::shared_ptr const& object); + QPDFObjGen next_id(); + QPDFObjectHandle make_indirect(std::shared_ptr const& obj); + std::shared_ptr get_for_parser(int id, int gen, bool parse_pdf); + std::shared_ptr get_for_json(int id, int gen); + + // Get a list of objects that would be permitted in an object stream. + template + std::vector compressible(); + std::vector compressible_vector(); + std::vector compressible_set(); + + // Used by QPDFWriter to determine the vector part of its object tables. + size_t table_size(); + + private: + struct Entry + { + Entry() = default; + + Entry(std::shared_ptr object) : + object(object) + { + } + + std::shared_ptr object; + }; + + bool cached(QPDFObjGen og); + bool unresolved(QPDFObjGen og); + + QPDFObjectHandle readObjectInStream(std::shared_ptr& input, int obj); + void resolveObjectsInStream(int obj_stream_number); + QPDFObjectHandle read_object(std::string const& description, QPDFObjGen og); + void read_stream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset); + void validate_stream_line_end(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset); + size_t recover_stream_length( + std::shared_ptr input, QPDFObjGen og, qpdf_offset_t stream_offset); + + QPDF& qpdf; + InputSource* const& file; + QPDF::Members* m; + Xref_table xref; + + std::map table; +}; // Objects + +#endif // QPDF_OBJECTS_HH diff --git a/libqpdf/qpdf/QPDF_private.hh b/libqpdf/qpdf/QPDF_private.hh index fa14fdc3..e628e053 100644 --- a/libqpdf/qpdf/QPDF_private.hh +++ b/libqpdf/qpdf/QPDF_private.hh @@ -3,378 +3,10 @@ #include +#include + #include -// Xref_table encapsulates the pdf's xref table and trailer. -class QPDF::Xref_table -{ - public: - Xref_table(QPDF& qpdf, InputSource* const& file) : - qpdf(qpdf), - file(file) - { - tokenizer.allowEOF(); - } - - void initialize(); - void initialize_empty(); - void initialize_json(); - void reconstruct(QPDFExc& e); - void show(); - bool resolve(); - - QPDFObjectHandle - trailer() const - { - return trailer_; - } - - void - trailer(QPDFObjectHandle&& oh) - { - trailer_ = std::move(oh); - } - - // Returns 0 if og is not in table. - size_t - type(QPDFObjGen og) const - { - int id = og.getObj(); - if (id < 1 || static_cast(id) >= table.size()) { - return 0; - } - auto& e = table[static_cast(id)]; - return e.gen() == og.getGen() ? e.type() : 0; - } - - // Returns 0 if og is not in table. - size_t - type(size_t id) const noexcept - { - if (id >= table.size()) { - return 0; - } - return table[id].type(); - } - - // Returns 0 if og is not in table. - qpdf_offset_t - offset(QPDFObjGen og) const noexcept - { - int id = og.getObj(); - if (id < 1 || static_cast(id) >= table.size()) { - return 0; - } - return table[static_cast(id)].offset(); - } - - // Returns 0 if id is not in table. - int - stream_number(int id) const noexcept - { - if (id < 1 || static_cast(id) >= table.size()) { - return 0; - } - return table[static_cast(id)].stream_number(); - } - - int - stream_index(int id) const noexcept - { - if (id < 1 || static_cast(id) >= table.size()) { - return 0; - } - return table[static_cast(id)].stream_index(); - } - - QPDFObjGen at_offset(qpdf_offset_t offset) const noexcept; - - std::map as_map() const; - - bool - object_streams() const noexcept - { - return object_streams_; - } - - // Return a vector of object id and stream number for each compressed object. - std::vector> - compressed_objects() const - { - if (!initialized()) { - throw std::logic_error("Xref_table::compressed_objects called before parsing."); - } - - std::vector> result; - result.reserve(table.size()); - - unsigned int i{0}; - for (auto const& item: table) { - if (item.type() == 2) { - result.emplace_back(i, item.stream_number()); - } - ++i; - } - return result; - } - - // Temporary access to underlying table size - size_t - size() const noexcept - { - return table.size(); - } - - void - ignore_streams(bool val) noexcept - { - ignore_streams_ = val; - } - - bool - initialized() const noexcept - { - return initialized_; - } - - void - attempt_recovery(bool val) noexcept - { - attempt_recovery_ = val; - } - - int - max_id() const noexcept - { - return max_id_; - } - - // For Linearization - - qpdf_offset_t - end_after_space(QPDFObjGen og) - { - auto& e = entry(toS(og.getObj())); - switch (e.type()) { - case 1: - return e.end_after_space_; - case 2: - { - auto es = entry(toS(e.stream_number())); - return es.type() == 1 ? es.end_after_space_ : 0; - } - default: - return 0; - } - } - - qpdf_offset_t - end_before_space(QPDFObjGen og) - { - auto& e = entry(toS(og.getObj())); - switch (e.type()) { - case 1: - return e.end_before_space_; - case 2: - { - auto es = entry(toS(e.stream_number())); - return es.type() == 1 ? es.end_before_space_ : 0; - } - default: - return 0; - } - } - - void - linearization_offsets(size_t id, qpdf_offset_t before, qpdf_offset_t after) - { - if (type(id)) { - table[id].end_before_space_ = before; - table[id].end_after_space_ = after; - } - } - - bool - uncompressed_after_compressed() const noexcept - { - return uncompressed_after_compressed_; - } - - // Actual value from file - qpdf_offset_t - first_item_offset() const noexcept - { - return first_item_offset_; - } - - private: - // Object, count, offset of first entry - typedef std::tuple Subsection; - - struct Uncompressed - { - Uncompressed(qpdf_offset_t offset) : - offset(offset) - { - } - qpdf_offset_t offset; - }; - - struct Compressed - { - Compressed(int stream_number, int stream_index) : - stream_number(stream_number), - stream_index(stream_index) - { - } - int stream_number{0}; - int stream_index{0}; - }; - - typedef std::variant Xref; - - struct Entry - { - Entry() = default; - - Entry(int gen, Xref entry) : - gen_(gen), - entry(entry) - { - } - - int - gen() const noexcept - { - return gen_; - } - - size_t - type() const noexcept - { - return entry.index(); - } - - qpdf_offset_t - offset() const noexcept - { - return type() == 1 ? std::get<1>(entry).offset : 0; - } - - int - stream_number() const noexcept - { - return type() == 2 ? std::get<2>(entry).stream_number : 0; - } - - int - stream_index() const noexcept - { - return type() == 2 ? std::get<2>(entry).stream_index : 0; - } - - int gen_{0}; - Xref entry; - qpdf_offset_t end_before_space_{0}; - qpdf_offset_t end_after_space_{0}; - }; - - Entry& - entry(size_t id) - { - return id < table.size() ? table[id] : table[0]; - } - - void read(qpdf_offset_t offset); - - // Methods to parse tables - qpdf_offset_t process_section(qpdf_offset_t offset); - std::vector subsections(std::string& line); - std::vector bad_subsections(std::string& line, qpdf_offset_t offset); - Subsection subsection(std::string const& line); - std::tuple read_entry(); - std::tuple read_bad_entry(); - - // Methods to parse streams - qpdf_offset_t read_stream(qpdf_offset_t offset); - qpdf_offset_t process_stream(qpdf_offset_t offset, QPDFObjectHandle& xref_stream); - std::pair> - process_W(QPDFObjectHandle& dict, std::function damaged); - std::pair process_Size( - QPDFObjectHandle& dict, int entry_size, std::function damaged); - std::pair>> process_Index( - QPDFObjectHandle& dict, - int max_num_entries, - std::function damaged); - - QPDFObjectHandle read_trailer(); - - QPDFTokenizer::Token - read_token(size_t max_len = 0) - { - return tokenizer.readToken(*file, "", true, max_len); - } - - // Methods to insert table entries - void insert(int obj, int f0, qpdf_offset_t f1, int f2); - void insert_free(QPDFObjGen); - - QPDFExc - damaged_pdf(std::string const& msg) - { - return qpdf.damagedPDF("", 0, msg); - } - - QPDFExc - damaged_table(std::string const& msg) - { - return qpdf.damagedPDF("xref table", msg); - } - - void - warn_damaged(std::string const& msg) - { - qpdf.warn(damaged_pdf(msg)); - } - - QPDF& qpdf; - InputSource* const& file; - QPDFTokenizer tokenizer; - - std::vector table; - QPDFObjectHandle trailer_; - - bool attempt_recovery_{true}; - bool initialized_{false}; - bool ignore_streams_{false}; - bool reconstructed_{false}; - bool object_streams_{false}; - // Before the xref table is initialized, max_id_ is an upper bound on the possible object ids - // that could be present in the PDF file. Once the trailer has been read, max_id_ is set to the - // value of /Size. If the file is damaged, max_id_ becomes the maximum object id in the xref - // table after reconstruction. - int max_id_{std::numeric_limits::max() - 1}; - - // Linearization data - bool uncompressed_after_compressed_{false}; - qpdf_offset_t first_item_offset_{0}; // actual value from file -}; - -// The Resolver class is restricted to QPDFObject so that only it can resolve indirect -// references. -class QPDF::Resolver -{ - friend class QPDFObject; - friend class QPDF_Unresolved; - - private: - static QPDFObject* - resolved(QPDF* qpdf, QPDFObjGen og) - { - return qpdf->resolve(og); - } -}; - // StreamCopier class is restricted to QPDFObjectHandle so it can copy stream data. class QPDF::StreamCopier { @@ -406,7 +38,7 @@ class QPDF::ParseGuard static std::shared_ptr getObject(QPDF* qpdf, int id, int gen, bool parse_pdf) { - return qpdf->getObjectForParser(id, gen, parse_pdf); + return qpdf->objects().get_for_parser(id, gen, parse_pdf); } ~ParseGuard() @@ -440,19 +72,6 @@ class QPDF::Pipe } }; -class QPDF::ObjCache -{ - public: - ObjCache() = default; - - ObjCache(std::shared_ptr object) : - object(object) - { - } - - std::shared_ptr object; -}; - class QPDF::ObjCopier { public: @@ -750,8 +369,7 @@ class QPDF::Members bool check_mode{false}; std::shared_ptr encp; std::string pdf_version; - Xref_table xref_table; - std::map obj_cache; + Objects objects; std::set resolving; std::vector all_pages; bool invalid_page_found{false}; @@ -800,6 +418,33 @@ class QPDF::Members std::map> object_to_obj_users; }; +inline QPDF::Objects& +QPDF::objects() noexcept +{ + return m->objects; +} + +inline QPDF::Objects const& +QPDF::objects() const noexcept +{ + return m->objects; +} + +// The Resolver class is restricted to QPDFObject so that only it can resolve indirect +// references. +class QPDF::Resolver +{ + friend class QPDFObject; + friend class QPDF_Unresolved; + + private: + static QPDFObject* + resolved(QPDF* qpdf, QPDFObjGen og) + { + return qpdf->m->objects.resolve(og); + } +}; + // JobSetter class is restricted to QPDFJob. class QPDF::JobSetter { @@ -876,25 +521,25 @@ class QPDF::Writer static std::vector getCompressibleObjGens(QPDF& qpdf) { - return qpdf.getCompressibleObjVector(); + return qpdf.objects().compressible_vector(); } static std::vector getCompressibleObjSet(QPDF& qpdf) { - return qpdf.getCompressibleObjSet(); + return qpdf.objects().compressible_set(); } - static Xref_table const& + static Objects::Xref_table const& getXRefTable(QPDF& qpdf) { - return qpdf.m->xref_table; + return qpdf.objects().xref_table(); } static size_t tableSize(QPDF& qpdf) { - return qpdf.tableSize(); + return qpdf.objects().table_size(); } };