From 9f0cc086b158b477ad942eb159b929b7b9ae7a0b Mon Sep 17 00:00:00 2001 From: m-holger Date: Sun, 6 Oct 2024 17:45:29 +0100 Subject: [PATCH] Copy QPDF.cc to new QPDF_objects --- libqpdf/QPDF_objects.cc | 2997 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 2997 insertions(+) create mode 100644 libqpdf/QPDF_objects.cc diff --git a/libqpdf/QPDF_objects.cc b/libqpdf/QPDF_objects.cc new file mode 100644 index 00000000..12b23a8d --- /dev/null +++ b/libqpdf/QPDF_objects.cc @@ -0,0 +1,2997 @@ +#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 +#include +#include +#include +#include + +// This must be a fixed value. This API returns a const reference to it, and the C API relies on its +// being static as well. +std::string const QPDF::qpdf_version(QPDF_VERSION); + +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 + +QPDF::ForeignStreamData::ForeignStreamData( + std::shared_ptr encp, + std::shared_ptr file, + QPDFObjGen const& foreign_og, + qpdf_offset_t offset, + size_t length, + QPDFObjectHandle local_dict) : + encp(encp), + file(file), + foreign_og(foreign_og), + offset(offset), + length(length), + local_dict(local_dict) +{ +} + +QPDF::CopiedStreamDataProvider::CopiedStreamDataProvider(QPDF& destination_qpdf) : + QPDFObjectHandle::StreamDataProvider(true), + destination_qpdf(destination_qpdf) +{ +} + +bool +QPDF::CopiedStreamDataProvider::provideStreamData( + QPDFObjGen const& og, Pipeline* pipeline, bool suppress_warnings, bool will_retry) +{ + std::shared_ptr foreign_data = foreign_stream_data[og]; + bool result = false; + if (foreign_data.get()) { + result = destination_qpdf.pipeForeignStreamData( + foreign_data, pipeline, suppress_warnings, will_retry); + QTC::TC("qpdf", "QPDF copy foreign with data", result ? 0 : 1); + } else { + auto foreign_stream = foreign_streams[og]; + result = foreign_stream.pipeStreamData( + pipeline, nullptr, 0, qpdf_dl_none, suppress_warnings, will_retry); + QTC::TC("qpdf", "QPDF copy foreign with foreign_stream", result ? 0 : 1); + } + return result; +} + +void +QPDF::CopiedStreamDataProvider::registerForeignStream( + QPDFObjGen const& local_og, QPDFObjectHandle foreign_stream) +{ + this->foreign_streams[local_og] = foreign_stream; +} + +void +QPDF::CopiedStreamDataProvider::registerForeignStream( + QPDFObjGen const& local_og, std::shared_ptr foreign_stream) +{ + this->foreign_stream_data[local_og] = foreign_stream; +} + +QPDF::StringDecrypter::StringDecrypter(QPDF* qpdf, QPDFObjGen const& og) : + qpdf(qpdf), + og(og) +{ +} + +void +QPDF::StringDecrypter::decryptString(std::string& val) +{ + qpdf->decryptString(val, og); +} + +std::string const& +QPDF::QPDFVersion() +{ + // The C API relies on this being a static value. + return QPDF::qpdf_version; +} + +QPDF::EncryptionParameters::EncryptionParameters() : + encrypted(false), + encryption_initialized(false), + encryption_V(0), + encryption_R(0), + encrypt_metadata(true), + cf_stream(e_none), + cf_string(e_none), + cf_file(e_none), + user_password_matched(false), + owner_password_matched(false) +{ +} + +QPDF::Members::Members(QPDF& qpdf) : + log(QPDFLogger::defaultLogger()), + file_sp(new InvalidInputSource(no_input_name)), + file(file_sp.get()), + encp(new EncryptionParameters), + xref_table(qpdf, file) +{ +} + +QPDF::QPDF() : + m(new Members(*this)) +{ + m->tokenizer.allowEOF(); + // Generate a unique ID. It just has to be unique among all QPDF objects allocated throughout + // the lifetime of this running application. + static std::atomic unique_id{0}; + 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(); + } + } +} + +std::shared_ptr +QPDF::create() +{ + return std::make_shared(); +} + +void +QPDF::processFile(char const* filename, char const* password) +{ + auto* fi = new FileInputSource(filename); + processInputSource(std::shared_ptr(fi), password); +} + +void +QPDF::processFile(char const* description, FILE* filep, bool close_file, char const* password) +{ + auto* fi = new FileInputSource(description, filep, close_file); + processInputSource(std::shared_ptr(fi), password); +} + +void +QPDF::processMemoryFile( + char const* description, char const* buf, size_t length, char const* password) +{ + processInputSource( + std::shared_ptr( + // line-break + new BufferInputSource( + description, new Buffer(QUtil::unsigned_char_pointer(buf), length), true)), + password); +} + +void +QPDF::processInputSource(std::shared_ptr source, char const* password) +{ + m->file_sp = source; + m->file = source.get(); + parse(password); +} + +void +QPDF::closeInputSource() +{ + m->no_input_name = "closed input source"; + m->file_sp = std::shared_ptr(new InvalidInputSource(m->no_input_name)); + m->file = m->file_sp.get(); +} + +void +QPDF::setPasswordIsHexKey(bool val) +{ + m->provided_password_is_hex_key = val; +} + +void +QPDF::emptyPDF() +{ + m->pdf_version = "1.3"; + m->no_input_name = "empty PDF"; + m->xref_table.initialize_empty(); +} + +void +QPDF::registerStreamFilter( + std::string const& filter_name, std::function()> factory) +{ + QPDF_Stream::registerStreamFilter(filter_name, factory); +} + +void +QPDF::setIgnoreXRefStreams(bool val) +{ + m->xref_table.ignore_streams(val); +} + +std::shared_ptr +QPDF::getLogger() +{ + return m->log; +} + +void +QPDF::setLogger(std::shared_ptr l) +{ + m->log = l; +} + +void +QPDF::setOutputStreams(std::ostream* out, std::ostream* err) +{ + setLogger(QPDFLogger::create()); + m->log->setOutputStreams(out, err); +} + +void +QPDF::setSuppressWarnings(bool val) +{ + m->suppress_warnings = val; +} + +void +QPDF::setMaxWarnings(size_t val) +{ + m->max_warnings = val; +} + +void +QPDF::setAttemptRecovery(bool val) +{ + m->attempt_recovery = val; + m->xref_table.attempt_recovery(val); +} + +void +QPDF::setImmediateCopyFrom(bool val) +{ + m->immediate_copy_from = val; +} + +std::vector +QPDF::getWarnings() +{ + std::vector result = m->warnings; + m->warnings.clear(); + return result; +} + +bool +QPDF::anyWarnings() const +{ + return !m->warnings.empty(); +} + +size_t +QPDF::numWarnings() const +{ + return m->warnings.size(); +} + +bool +QPDF::validatePDFVersion(char const*& p, std::string& version) +{ + bool valid = QUtil::is_digit(*p); + if (valid) { + while (QUtil::is_digit(*p)) { + version.append(1, *p++); + } + if ((*p == '.') && QUtil::is_digit(*(p + 1))) { + version.append(1, *p++); + while (QUtil::is_digit(*p)) { + version.append(1, *p++); + } + } else { + valid = false; + } + } + return valid; +} + +bool +QPDF::findHeader() +{ + qpdf_offset_t global_offset = m->file->tell(); + std::string line = m->file->readLine(1024); + char const* p = line.c_str(); + if (strncmp(p, "%PDF-", 5) != 0) { + throw std::logic_error("findHeader is not looking at %PDF-"); + } + p += 5; + std::string version; + // Note: The string returned by line.c_str() is always null-terminated. The code below never + // overruns the buffer because a null character always short-circuits further advancement. + bool valid = validatePDFVersion(p, version); + if (valid) { + m->pdf_version = version; + if (global_offset != 0) { + // Empirical evidence strongly suggests that when there is leading material prior to the + // PDF header, all explicit offsets in the file are such that 0 points to the beginning + // of the header. + QTC::TC("qpdf", "QPDF global offset"); + m->file_sp = + std::shared_ptr(new OffsetInputSource(m->file_sp, global_offset)); + m->file = m->file_sp.get(); + } + } + 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) +{ + if (password) { + m->encp->provided_password = password; + } + + // Find the header anywhere in the first 1024 bytes of the file. + PatternFinder hf(*this, &QPDF::findHeader); + if (!m->file->findFirst("%PDF-", 0, 1024, hf)) { + QTC::TC("qpdf", "QPDF not a pdf file"); + warn(damagedPDF("", 0, "can't find PDF header")); + // QPDFWriter writes files that usually require at least version 1.2 for /FlateDecode + m->pdf_version = "1.2"; + } + + m->xref_table.initialize(); + initializeEncryption(); + if (m->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"); + } +} + +void +QPDF::inParse(bool v) +{ + if (m->in_parse == v) { + // This happens if QPDFParser::parse tries to resolve an indirect object while it is + // parsing. + throw std::logic_error("QPDF: re-entrant parsing detected. This is a qpdf bug." + " Please report at https://github.com/qpdf/qpdf/issues."); + } + m->in_parse = v; +} + +void +QPDF::warn(QPDFExc const& e) +{ + if (m->max_warnings > 0 && m->warnings.size() >= m->max_warnings) { + stopOnError("Too many warnings - file is too badly damaged"); + } + m->warnings.push_back(e); + if (!m->suppress_warnings) { + *m->log->getWarn() << "WARNING: " << m->warnings.back().what() << "\n"; + } +} + +void +QPDF::warn( + qpdf_error_code_e error_code, + std::string const& object, + qpdf_offset_t offset, + std::string const& message) +{ + 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; +} + +// Ensure all objects in the pdf file, including those in indirect references, appear in the object +// cache. +void +QPDF::fixDanglingReferences(bool force) +{ + if (m->fixed_dangling_refs) { + return; + } + if (!m->xref_table.resolve()) { + QTC::TC("qpdf", "QPDF fix dangling triggered xref reconstruction"); + m->xref_table.resolve(); + } + m->fixed_dangling_refs = true; +} + +size_t +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()); +} + +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; +} + +void +QPDF::setLastObjectDescription(std::string const& description, QPDFObjGen const& og) +{ + m->last_object_description.clear(); + if (!description.empty()) { + m->last_object_description += description; + if (og.isIndirect()) { + m->last_object_description += ": "; + } + } + if (og.isIndirect()) { + m->last_object_description += "object " + og.unparse(' '); + } +} + +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) +{ + obj->setDefaultDescription(this, og); + 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()); +} + +QPDFObjectHandle +QPDF::newReserved() +{ + return makeIndirectFromQPDFObject(QPDF_Reserved::create()); +} + +QPDFObjectHandle +QPDF::newIndirectNull() +{ + return makeIndirectFromQPDFObject(QPDF_Null::create()); +} + +QPDFObjectHandle +QPDF::newStream() +{ + return makeIndirectFromQPDFObject( + QPDF_Stream::create(this, nextObjGen(), QPDFObjectHandle::newDictionary(), 0, 0)); +} + +QPDFObjectHandle +QPDF::newStream(std::shared_ptr data) +{ + auto result = newStream(); + result.replaceStreamData(data, QPDFObjectHandle::newNull(), QPDFObjectHandle::newNull()); + return result; +} + +QPDFObjectHandle +QPDF::newStream(std::string const& data) +{ + auto result = newStream(); + result.replaceStreamData(data, QPDFObjectHandle::newNull(), QPDFObjectHandle::newNull()); + 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}; + } +} + +QPDFObjectHandle +QPDF::getObject(int objid, int generation) +{ + return getObject(QPDFObjGen(objid, generation)); +} + +QPDFObjectHandle +QPDF::getObjectByObjGen(QPDFObjGen const& og) +{ + return getObject(og); +} + +QPDFObjectHandle +QPDF::getObjectByID(int objid, int generation) +{ + return getObject(QPDFObjGen(objid, generation)); +} + +void +QPDF::replaceObject(int objid, int generation, QPDFObjectHandle oh) +{ + replaceObject(QPDFObjGen(objid, generation), oh); +} + +void +QPDF::replaceObject(QPDFObjGen const& 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"); + } + 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); + } +} + +void +QPDF::replaceReserved(QPDFObjectHandle reserved, QPDFObjectHandle replacement) +{ + QTC::TC("qpdf", "QPDF replaceReserved"); + auto tc = reserved.getTypeCode(); + if (!(tc == ::ot_reserved || tc == ::ot_null)) { + throw std::logic_error("replaceReserved called with non-reserved object"); + } + replaceObject(reserved.getObjGen(), replacement); +} + +QPDFObjectHandle +QPDF::copyForeignObject(QPDFObjectHandle foreign) +{ + // Here's an explanation of what's going on here. + // + // A QPDFObjectHandle that is an indirect object has an owning QPDF. The object ID and + // generation refers to an object in the owning QPDF. When we copy the QPDFObjectHandle from a + // foreign QPDF into the local QPDF, we have to replace all indirect object references with + // references to the corresponding object in the local file. + // + // To do this, we maintain mappings from foreign object IDs to local object IDs for each foreign + // QPDF that we are copying from. The mapping is stored in an ObjCopier, which contains a + // mapping from the foreign ObjGen to the local QPDFObjectHandle. + // + // To copy, we do a deep traversal of the foreign object with loop detection to discover all + // indirect objects that are encountered, stopping at page boundaries. Whenever we encounter an + // indirect object, we check to see if we have already created a local copy of it. If not, we + // allocate a "reserved" object (or, for a stream, just a new stream) and store in the map the + // mapping from the foreign object ID to the new object. While we + // do this, we keep a list of objects to copy. + // + // Once we are done with the traversal, we copy all the objects that we need to copy. However, + // the copies will contain indirect object IDs that refer to objects in the foreign file. We + // need to replace them with references to objects in the local file. This is what + // replaceForeignIndirectObjects does. Once we have created a copy of the foreign object with + // all the indirect references replaced with new ones in the local context, we can replace the + // local reserved object with the copy. This mechanism allows us to copy objects with circular + // references in any order. + + // For streams, rather than copying the objects, we set up the stream data to pull from the + // original stream by using a stream data provider. This is done in a manner that doesn't + // require the original QPDF object but may require the original source of the stream data with + // special handling for immediate_copy_from. This logic is also in + // replaceForeignIndirectObjects. + + // Note that we explicitly allow use of copyForeignObject on page objects. It is a documented + // use case to copy pages this way if the intention is to not update the pages tree. + if (!foreign.isIndirect()) { + QTC::TC("qpdf", "QPDF copyForeign direct"); + throw std::logic_error("QPDF::copyForeign called with direct object handle"); + } + QPDF& other = foreign.getQPDF(); + if (&other == this) { + QTC::TC("qpdf", "QPDF copyForeign not foreign"); + throw std::logic_error("QPDF::copyForeign called with object from this QPDF"); + } + + ObjCopier& obj_copier = m->object_copiers[other.m->unique_id]; + if (!obj_copier.visiting.empty()) { + throw std::logic_error("obj_copier.visiting is not empty" + " at the beginning of copyForeignObject"); + } + + // Make sure we have an object in this file for every referenced object in the old file. + // obj_copier.object_map maps foreign QPDFObjGen to local objects. For everything new that we + // have to copy, the local object will be a reservation, unless it is a stream, in which case + // the local object will already be a stream. + reserveObjects(foreign, obj_copier, true); + + if (!obj_copier.visiting.empty()) { + throw std::logic_error("obj_copier.visiting is not empty after reserving objects"); + } + + // Copy any new objects and replace the reservations. + for (auto& to_copy: obj_copier.to_copy) { + QPDFObjectHandle copy = replaceForeignIndirectObjects(to_copy, obj_copier, true); + if (!to_copy.isStream()) { + QPDFObjGen og(to_copy.getObjGen()); + replaceReserved(obj_copier.object_map[og], copy); + } + } + obj_copier.to_copy.clear(); + + auto og = foreign.getObjGen(); + if (!obj_copier.object_map.count(og)) { + warn(damagedPDF("unexpected reference to /Pages object while copying foreign object; " + "replacing with null")); + return QPDFObjectHandle::newNull(); + } + return obj_copier.object_map[foreign.getObjGen()]; +} + +void +QPDF::reserveObjects(QPDFObjectHandle foreign, ObjCopier& obj_copier, bool top) +{ + auto foreign_tc = foreign.getTypeCode(); + if (foreign_tc == ::ot_reserved) { + throw std::logic_error("QPDF: attempting to copy a foreign reserved object"); + } + + if (foreign.isPagesObject()) { + QTC::TC("qpdf", "QPDF not copying pages object"); + return; + } + + if (foreign.isIndirect()) { + QPDFObjGen foreign_og(foreign.getObjGen()); + if (!obj_copier.visiting.add(foreign_og)) { + QTC::TC("qpdf", "QPDF loop reserving objects"); + return; + } + if (obj_copier.object_map.count(foreign_og) > 0) { + QTC::TC("qpdf", "QPDF already reserved object"); + if (!(top && foreign.isPageObject() && obj_copier.object_map[foreign_og].isNull())) { + obj_copier.visiting.erase(foreign); + return; + } + } else { + QTC::TC("qpdf", "QPDF copy indirect"); + obj_copier.object_map[foreign_og] = + foreign.isStream() ? newStream() : newIndirectNull(); + if ((!top) && foreign.isPageObject()) { + QTC::TC("qpdf", "QPDF not crossing page boundary"); + obj_copier.visiting.erase(foreign_og); + return; + } + } + obj_copier.to_copy.push_back(foreign); + } + + if (foreign_tc == ::ot_array) { + QTC::TC("qpdf", "QPDF reserve array"); + int n = foreign.getArrayNItems(); + for (int i = 0; i < n; ++i) { + reserveObjects(foreign.getArrayItem(i), obj_copier, false); + } + } else if (foreign_tc == ::ot_dictionary) { + QTC::TC("qpdf", "QPDF reserve dictionary"); + for (auto const& key: foreign.getKeys()) { + reserveObjects(foreign.getKey(key), obj_copier, false); + } + } else if (foreign_tc == ::ot_stream) { + QTC::TC("qpdf", "QPDF reserve stream"); + reserveObjects(foreign.getDict(), obj_copier, false); + } + + obj_copier.visiting.erase(foreign); +} + +QPDFObjectHandle +QPDF::replaceForeignIndirectObjects(QPDFObjectHandle foreign, ObjCopier& obj_copier, bool top) +{ + auto foreign_tc = foreign.getTypeCode(); + QPDFObjectHandle result; + if ((!top) && foreign.isIndirect()) { + QTC::TC("qpdf", "QPDF replace indirect"); + auto mapping = obj_copier.object_map.find(foreign.getObjGen()); + if (mapping == obj_copier.object_map.end()) { + // This case would occur if this is a reference to a Pages object that we didn't + // traverse into. + QTC::TC("qpdf", "QPDF replace foreign indirect with null"); + result = QPDFObjectHandle::newNull(); + } else { + result = mapping->second; + } + } else if (foreign_tc == ::ot_array) { + QTC::TC("qpdf", "QPDF replace array"); + result = QPDFObjectHandle::newArray(); + int n = foreign.getArrayNItems(); + for (int i = 0; i < n; ++i) { + result.appendItem( + // line-break + replaceForeignIndirectObjects(foreign.getArrayItem(i), obj_copier, false)); + } + } else if (foreign_tc == ::ot_dictionary) { + QTC::TC("qpdf", "QPDF replace dictionary"); + result = QPDFObjectHandle::newDictionary(); + std::set keys = foreign.getKeys(); + for (auto const& iter: keys) { + result.replaceKey( + iter, replaceForeignIndirectObjects(foreign.getKey(iter), obj_copier, false)); + } + } else if (foreign_tc == ::ot_stream) { + QTC::TC("qpdf", "QPDF replace stream"); + result = obj_copier.object_map[foreign.getObjGen()]; + result.assertStream(); + QPDFObjectHandle dict = result.getDict(); + QPDFObjectHandle old_dict = foreign.getDict(); + std::set keys = old_dict.getKeys(); + for (auto const& iter: keys) { + dict.replaceKey( + iter, replaceForeignIndirectObjects(old_dict.getKey(iter), obj_copier, false)); + } + copyStreamData(result, foreign); + } else { + foreign.assertScalar(); + result = foreign; + result.makeDirect(); + } + + if (top && (!result.isStream()) && result.isIndirect()) { + throw std::logic_error("replacement for foreign object is indirect"); + } + + return result; +} + +void +QPDF::copyStreamData(QPDFObjectHandle result, QPDFObjectHandle foreign) +{ + // This method was originally written for copying foreign streams, but it is used by + // QPDFObjectHandle to copy streams from the same QPDF object as well. + + QPDFObjectHandle dict = result.getDict(); + QPDFObjectHandle old_dict = foreign.getDict(); + if (m->copied_stream_data_provider == nullptr) { + m->copied_stream_data_provider = new CopiedStreamDataProvider(*this); + m->copied_streams = + std::shared_ptr(m->copied_stream_data_provider); + } + QPDFObjGen local_og(result.getObjGen()); + // Copy information from the foreign stream so we can pipe its data later without keeping the + // original QPDF object around. + + QPDF& foreign_stream_qpdf = + foreign.getQPDF("unable to retrieve owning qpdf from foreign stream"); + + auto stream = foreign.getObjectPtr()->as(); + if (stream == nullptr) { + throw std::logic_error("unable to retrieve underlying" + " stream object from foreign stream"); + } + std::shared_ptr stream_buffer = stream->getStreamDataBuffer(); + if ((foreign_stream_qpdf.m->immediate_copy_from) && (stream_buffer == nullptr)) { + // Pull the stream data into a buffer before attempting the copy operation. Do it on the + // source stream so that if the source stream is copied multiple times, we don't have to + // keep duplicating the memory. + QTC::TC("qpdf", "QPDF immediate copy stream data"); + foreign.replaceStreamData( + foreign.getRawStreamData(), + old_dict.getKey("/Filter"), + old_dict.getKey("/DecodeParms")); + stream_buffer = stream->getStreamDataBuffer(); + } + std::shared_ptr stream_provider = + stream->getStreamDataProvider(); + if (stream_buffer.get()) { + QTC::TC("qpdf", "QPDF copy foreign stream with buffer"); + result.replaceStreamData( + stream_buffer, dict.getKey("/Filter"), dict.getKey("/DecodeParms")); + } else if (stream_provider.get()) { + // In this case, the remote stream's QPDF must stay in scope. + QTC::TC("qpdf", "QPDF copy foreign stream with provider"); + m->copied_stream_data_provider->registerForeignStream(local_og, foreign); + result.replaceStreamData( + m->copied_streams, dict.getKey("/Filter"), dict.getKey("/DecodeParms")); + } else { + auto foreign_stream_data = std::make_shared( + foreign_stream_qpdf.m->encp, + foreign_stream_qpdf.m->file_sp, + foreign.getObjGen(), + stream->getParsedOffset(), + stream->getLength(), + dict); + m->copied_stream_data_provider->registerForeignStream(local_og, foreign_stream_data); + result.replaceStreamData( + m->copied_streams, dict.getKey("/Filter"), dict.getKey("/DecodeParms")); + } +} + +void +QPDF::swapObjects(int objid1, int generation1, int objid2, int generation2) +{ + swapObjects(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); +} + +unsigned long long +QPDF::getUniqueId() const +{ + return m->unique_id; +} + +std::string +QPDF::getFilename() const +{ + return m->file->getName(); +} + +PDFVersion +QPDF::getVersionAsPDFVersion() +{ + int major = 1; + int minor = 3; + int extension_level = getExtensionLevel(); + + std::regex v("^[[:space:]]*([0-9]+)\\.([0-9]+)"); + std::smatch match; + if (std::regex_search(m->pdf_version, match, v)) { + major = QUtil::string_to_int(match[1].str().c_str()); + minor = QUtil::string_to_int(match[2].str().c_str()); + } + + return {major, minor, extension_level}; +} + +std::string +QPDF::getPDFVersion() const +{ + return m->pdf_version; +} + +int +QPDF::getExtensionLevel() +{ + int result = 0; + QPDFObjectHandle obj = getRoot(); + if (obj.hasKey("/Extensions")) { + obj = obj.getKey("/Extensions"); + if (obj.isDictionary() && obj.hasKey("/ADBE")) { + obj = obj.getKey("/ADBE"); + if (obj.isDictionary() && obj.hasKey("/ExtensionLevel")) { + obj = obj.getKey("/ExtensionLevel"); + if (obj.isInteger()) { + result = obj.getIntValueAsInt(); + } + } + } + } + return result; +} + +QPDFObjectHandle +QPDF::getTrailer() +{ + return m->xref_table.trailer(); +} + +QPDFObjectHandle +QPDF::getRoot() +{ + QPDFObjectHandle root = m->xref_table.trailer().getKey("/Root"); + if (!root.isDictionary()) { + throw damagedPDF("", 0, "unable to find /Root dictionary"); + } else if ( + // Check_mode is an interim solution to request #810 pending a more comprehensive review of + // the approach to more extensive checks and warning levels. + m->check_mode && !root.getKey("/Type").isNameAndEquals("/Catalog")) { + warn(damagedPDF("", 0, "catalog /Type entry missing or invalid")); + root.replaceKey("/Type", "/Catalog"_qpdf); + } + return root; +} + +std::map +QPDF::getXRefTable() +{ + if (!m->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; +} + +bool +QPDF::pipeStreamData( + std::shared_ptr encp, + std::shared_ptr file, + QPDF& qpdf_for_warning, + QPDFObjGen const& og, + qpdf_offset_t offset, + size_t length, + QPDFObjectHandle stream_dict, + Pipeline* pipeline, + bool suppress_warnings, + bool will_retry) +{ + std::unique_ptr to_delete; + if (encp->encrypted) { + decryptStream(encp, file, qpdf_for_warning, pipeline, og, stream_dict, to_delete); + } + + bool attempted_finish = false; + try { + file->seek(offset, SEEK_SET); + auto buf = std::make_unique(length); + if (auto read = file->read(buf.get(), length); read != length) { + throw damagedPDF(*file, "", offset + toO(read), "unexpected EOF reading stream data"); + } + pipeline->write(buf.get(), length); + attempted_finish = true; + pipeline->finish(); + return true; + } catch (QPDFExc& e) { + if (!suppress_warnings) { + qpdf_for_warning.warn(e); + } + } catch (std::exception& e) { + if (!suppress_warnings) { + QTC::TC("qpdf", "QPDF decoding error warning"); + qpdf_for_warning.warn( + // line-break + damagedPDF( + *file, + "", + file->getLastOffset(), + ("error decoding stream data for object " + og.unparse(' ') + ": " + + e.what()))); + if (will_retry) { + qpdf_for_warning.warn( + // line-break + damagedPDF( + *file, + "", + file->getLastOffset(), + "stream will be re-processed without filtering to avoid data loss")); + } + } + } + if (!attempted_finish) { + try { + pipeline->finish(); + } catch (std::exception&) { + // ignore + } + } + return false; +} + +bool +QPDF::pipeStreamData( + QPDFObjGen const& og, + qpdf_offset_t offset, + size_t length, + QPDFObjectHandle stream_dict, + Pipeline* pipeline, + bool suppress_warnings, + bool will_retry) +{ + return pipeStreamData( + m->encp, + m->file_sp, + *this, + og, + offset, + length, + stream_dict, + pipeline, + suppress_warnings, + will_retry); +} + +bool +QPDF::pipeForeignStreamData( + std::shared_ptr foreign, + Pipeline* pipeline, + bool suppress_warnings, + bool will_retry) +{ + if (foreign->encp->encrypted) { + QTC::TC("qpdf", "QPDF pipe foreign encrypted stream"); + } + return pipeStreamData( + foreign->encp, + foreign->file, + *this, + foreign->foreign_og, + foreign->offset, + foreign->length, + foreign->local_dict, + pipeline, + suppress_warnings, + will_retry); +} + +// Throw a generic exception when we lack context for something more specific. New code should not +// use this. This method exists to improve somewhat from calling assert in very old code. +void +QPDF::stopOnError(std::string const& message) +{ + throw damagedPDF("", message); +} + +// Return an exception of type qpdf_e_damaged_pdf. +QPDFExc +QPDF::damagedPDF( + InputSource& input, std::string const& object, qpdf_offset_t offset, std::string const& message) +{ + return {qpdf_e_damaged_pdf, input.getName(), object, offset, message}; +} + +// Return an exception of type qpdf_e_damaged_pdf. The object is taken from +// m->last_object_description. +QPDFExc +QPDF::damagedPDF(InputSource& input, qpdf_offset_t offset, std::string const& message) +{ + return damagedPDF(input, m->last_object_description, offset, message); +} + +// Return an exception of type qpdf_e_damaged_pdf. The filename is taken from m->file. +QPDFExc +QPDF::damagedPDF(std::string const& object, qpdf_offset_t offset, std::string const& message) +{ + return {qpdf_e_damaged_pdf, m->file->getName(), object, offset, message}; +} + +// Return an exception of type qpdf_e_damaged_pdf. The filename is taken from m->file and the +// offset from .m->file->getLastOffset(). +QPDFExc +QPDF::damagedPDF(std::string const& object, std::string const& message) +{ + return damagedPDF(object, m->file->getLastOffset(), message); +} + +// Return an exception of type qpdf_e_damaged_pdf. The filename is taken from m->file and the object +// from .m->last_object_description. +QPDFExc +QPDF::damagedPDF(qpdf_offset_t offset, std::string const& message) +{ + return damagedPDF(m->last_object_description, offset, message); +} + +// Return an exception of type qpdf_e_damaged_pdf. The filename is taken from m->file, the object +// from m->last_object_description and the offset from m->file->getLastOffset(). +QPDFExc +QPDF::damagedPDF(std::string const& message) +{ + return damagedPDF(m->last_object_description, m->file->getLastOffset(), message); +} + +bool +QPDF::everCalledGetAllPages() const +{ + return m->ever_called_get_all_pages; +} + +bool +QPDF::everPushedInheritedAttributesToPages() const +{ + return m->ever_pushed_inherited_attributes_to_pages; +} + +void +QPDF::removeSecurityRestrictions() +{ + auto root = getRoot(); + root.removeKey("/Perms"); + auto acroform = root.getKey("/AcroForm"); + if (acroform.isDictionary() && acroform.hasKey("/SigFlags")) { + acroform.replaceKey("/SigFlags", QPDFObjectHandle::newInteger(0)); + } +}