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837dcf8fc2
qpdf/libqpdf/QPDF.cc
Jay Berkenbilt 837dcf8fc2 Don't call assert while checking linearization data (fixes #209, #231) 
Instead of calling assert for problems found during checking
linearization data, throw an exception which is later caught and
issued as an error. Ideally we would handle errors more robustly, but
this is still a significant improvement.
2019-01-04 11:55:42 -05:00

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#include <qpdf/qpdf-config.h> // include first for large file support
#include <qpdf/QPDF.hh>
#include <vector>
#include <map>
#include <algorithm>
#include <string.h>
#include <memory.h>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/Pipeline.hh>
#include <qpdf/Pl_Discard.hh>
#include <qpdf/FileInputSource.hh>
#include <qpdf/BufferInputSource.hh>
#include <qpdf/OffsetInputSource.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/QPDF_Null.hh>
#include <qpdf/QPDF_Dictionary.hh>
std::string QPDF::qpdf_version = "8.2.1";
static char const* EMPTY_PDF =
"%PDF-1.3\n"
"1 0 obj\n"
"<< /Type /Catalog /Pages 2 0 R >>\n"
"endobj\n"
"2 0 obj\n"
"<< /Type /Pages /Kids [] /Count 0 >>\n"
"endobj\n"
"xref\n"
"0 3\n"
"0000000000 65535 f \n"
"0000000009 00000 n \n"
"0000000058 00000 n \n"
"trailer << /Size 3 /Root 1 0 R >>\n"
"startxref\n"
"110\n"
"%%EOF\n";
void
QPDF::CopiedStreamDataProvider::provideStreamData(
int objid, int generation, Pipeline* pipeline)
{
QPDFObjectHandle foreign_stream =
this->foreign_streams[QPDFObjGen(objid, generation)];
foreign_stream.pipeStreamData(pipeline, 0, qpdf_dl_none);
}
void
QPDF::CopiedStreamDataProvider::registerForeignStream(
QPDFObjGen const& local_og, QPDFObjectHandle foreign_stream)
{
this->foreign_streams[local_og] = foreign_stream;
}
QPDF::StringDecrypter::StringDecrypter(QPDF* qpdf, int objid, int gen) :
qpdf(qpdf),
objid(objid),
gen(gen)
{
}
void
QPDF::StringDecrypter::decryptString(std::string& val)
{
qpdf->decryptString(val, objid, gen);
}
std::string const&
QPDF::QPDFVersion()
{
return QPDF::qpdf_version;
}
QPDF::Members::Members() :
provided_password_is_hex_key(false),
encrypted(false),
encryption_initialized(false),
ignore_xref_streams(false),
suppress_warnings(false),
out_stream(&std::cout),
err_stream(&std::cerr),
attempt_recovery(true),
encryption_V(0),
encryption_R(0),
encrypt_metadata(true),
cf_stream(e_none),
cf_string(e_none),
cf_file(e_none),
cached_key_objid(0),
cached_key_generation(0),
pushed_inherited_attributes_to_pages(false),
copied_stream_data_provider(0),
reconstructed_xref(false),
fixed_dangling_refs(false),
first_xref_item_offset(0),
uncompressed_after_compressed(false)
{
}
QPDF::Members::~Members()
{
}
QPDF::QPDF() :
m(new Members())
{
m->tokenizer.allowEOF();
}
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
// PointerHolder 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 references. At this point, obviously no one is still
// using the QPDF object, but we'll explicitly clear the xref
// table anyway just to prevent any possibility of resolve()
// succeeding. Note that we can't break references like this at
// any time when the QPDF object is active. If we do, the next
// reference will reread the object from the file, which would
// have the effect of undoing any modifications that may have been
// made to any of the objects.
this->m->xref_table.clear();
for (std::map<QPDFObjGen, ObjCache>::iterator iter =
this->m->obj_cache.begin();
iter != this->m->obj_cache.end(); ++iter)
{
QPDFObject::ObjAccessor::releaseResolved(
(*iter).second.object.getPointer());
}
}
void
QPDF::processFile(char const* filename, char const* password)
{
FileInputSource* fi = new FileInputSource();
fi->setFilename(filename);
processInputSource(fi, password);
}
void
QPDF::processFile(char const* description, FILE* filep,
bool close_file, char const* password)
{
FileInputSource* fi = new FileInputSource();
fi->setFile(description, filep, close_file);
processInputSource(fi, password);
}
void
QPDF::processMemoryFile(char const* description,
char const* buf, size_t length,
char const* password)
{
processInputSource(
new BufferInputSource(
description,
new Buffer(QUtil::unsigned_char_pointer(buf), length),
true),
password);
}
void
QPDF::processInputSource(PointerHolder<InputSource> source,
char const* password)
{
this->m->file = source;
parse(password);
}
void
QPDF::setPasswordIsHexKey(bool val)
{
this->m->provided_password_is_hex_key = val;
}
void
QPDF::emptyPDF()
{
processMemoryFile("empty PDF", EMPTY_PDF, strlen(EMPTY_PDF));
}
void
QPDF::setIgnoreXRefStreams(bool val)
{
this->m->ignore_xref_streams = val;
}
void
QPDF::setOutputStreams(std::ostream* out, std::ostream* err)
{
this->m->out_stream = out ? out : &std::cout;
this->m->err_stream = err ? err : &std::cerr;
}
void
QPDF::setSuppressWarnings(bool val)
{
this->m->suppress_warnings = val;
}
void
QPDF::setAttemptRecovery(bool val)
{
this->m->attempt_recovery = val;
}
std::vector<QPDFExc>
QPDF::getWarnings()
{
std::vector<QPDFExc> result = this->m->warnings;
this->m->warnings.clear();
return result;
}
bool
QPDF::findHeader()
{
qpdf_offset_t global_offset = this->m->file->tell();
std::string line = this->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 = 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;
}
}
if (valid)
{
this->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");
this->m->file = new OffsetInputSource(this->m->file, global_offset);
}
}
return valid;
}
bool
QPDF::findStartxref()
{
QPDFTokenizer::Token t = readToken(this->m->file);
if (t == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "startxref"))
{
t = readToken(this->m->file);
if (t.getType() == QPDFTokenizer::tt_integer)
{
// Position in front of offset token
this->m->file->seek(this->m->file->getLastOffset(), SEEK_SET);
return true;
}
}
return false;
}
void
QPDF::parse(char const* password)
{
if (password)
{
this->m->provided_password = password;
}
// Find the header anywhere in the first 1024 bytes of the file.
PatternFinder hf(*this, &QPDF::findHeader);
if (! this->m->file->findFirst("%PDF-", 0, 1024, hf))
{
QTC::TC("qpdf", "QPDF not a pdf file");
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", 0, "can't find PDF header"));
// QPDFWriter writes files that usually require at least
// version 1.2 for /FlateDecode
this->m->pdf_version = "1.2";
}
if (atof(this->m->pdf_version.c_str()) < 1.2)
{
this->m->tokenizer.allowPoundAnywhereInName();
}
// 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.
this->m->file->seek(0, SEEK_END);
qpdf_offset_t end_offset = this->m->file->tell();
qpdf_offset_t start_offset = (end_offset > 1054 ? end_offset - 1054 : 0);
PatternFinder sf(*this, &QPDF::findStartxref);
qpdf_offset_t xref_offset = 0;
if (this->m->file->findLast("startxref", start_offset, 0, sf))
{
xref_offset = QUtil::string_to_ll(
readToken(this->m->file).getValue().c_str());
}
try
{
if (xref_offset == 0)
{
QTC::TC("qpdf", "QPDF can't find startxref");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"can't find startxref");
}
read_xref(xref_offset);
}
catch (QPDFExc& e)
{
if (this->m->attempt_recovery)
{
reconstruct_xref(e);
QTC::TC("qpdf", "QPDF reconstructed xref table");
}
else
{
throw e;
}
}
initializeEncryption();
findAttachmentStreams();
}
void
QPDF::warn(QPDFExc const& e)
{
this->m->warnings.push_back(e);
if (! this->m->suppress_warnings)
{
*this->m->err_stream
<< "WARNING: "
<< this->m->warnings.back().what() << std::endl;
}
}
void
QPDF::setTrailer(QPDFObjectHandle obj)
{
if (this->m->trailer.isInitialized())
{
return;
}
this->m->trailer = obj;
}
void
QPDF::reconstruct_xref(QPDFExc& e)
{
if (this->m->reconstructed_xref)
{
// 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;
}
this->m->reconstructed_xref = true;
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"file is damaged"));
warn(e);
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"Attempting to reconstruct cross-reference table"));
// Delete all references to type 1 (uncompressed) objects
std::set<QPDFObjGen> to_delete;
for (std::map<QPDFObjGen, QPDFXRefEntry>::iterator iter =
this->m->xref_table.begin();
iter != this->m->xref_table.end(); ++iter)
{
if (((*iter).second).getType() == 1)
{
to_delete.insert((*iter).first);
}
}
for (std::set<QPDFObjGen>::iterator iter = to_delete.begin();
iter != to_delete.end(); ++iter)
{
this->m->xref_table.erase(*iter);
}
this->m->file->seek(0, SEEK_END);
qpdf_offset_t eof = this->m->file->tell();
this->m->file->seek(0, SEEK_SET);
bool in_obj = false;
qpdf_offset_t line_start = 0;
// Don't allow very long tokens here during recovery.
static size_t const MAX_LEN = 100;
while (this->m->file->tell() < eof)
{
this->m->file->findAndSkipNextEOL();
qpdf_offset_t next_line_start = this->m->file->tell();
this->m->file->seek(line_start, SEEK_SET);
QPDFTokenizer::Token t1 = readToken(this->m->file, MAX_LEN);
qpdf_offset_t token_start =
this->m->file->tell() - t1.getValue().length();
if (token_start >= next_line_start)
{
// don't process yet
}
else if (in_obj)
{
if (t1 == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "endobj"))
{
in_obj = false;
}
}
else
{
if (t1.getType() == QPDFTokenizer::tt_integer)
{
QPDFTokenizer::Token t2 =
readToken(this->m->file, MAX_LEN);
QPDFTokenizer::Token t3 =
readToken(this->m->file, MAX_LEN);
if ((t2.getType() == QPDFTokenizer::tt_integer) &&
(t3 == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "obj")))
{
in_obj = true;
int obj = QUtil::string_to_int(t1.getValue().c_str());
int gen = QUtil::string_to_int(t2.getValue().c_str());
insertXrefEntry(obj, 1, token_start, gen, true);
}
}
else if ((! this->m->trailer.isInitialized()) &&
(t1 == QPDFTokenizer::Token(
QPDFTokenizer::tt_word, "trailer")))
{
QPDFObjectHandle t =
readObject(this->m->file, "trailer", 0, 0, false);
if (! t.isDictionary())
{
// Oh well. It was worth a try.
}
else
{
setTrailer(t);
}
}
}
this->m->file->seek(next_line_start, SEEK_SET);
line_start = next_line_start;
}
if (! this->m->trailer.isInitialized())
{
// 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 QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"unable to find trailer "
"dictionary 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::read_xref(qpdf_offset_t xref_offset)
{
std::map<int, int> free_table;
std::set<qpdf_offset_t> visited;
while (xref_offset)
{
visited.insert(xref_offset);
char buf[7];
memset(buf, 0, sizeof(buf));
this->m->file->seek(xref_offset, SEEK_SET);
this->m->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]))
{
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 = read_xrefTable(xref_offset + skip);
}
else
{
xref_offset = read_xrefStream(xref_offset);
}
if (visited.count(xref_offset) != 0)
{
QTC::TC("qpdf", "QPDF xref loop");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"loop detected following xref tables");
}
}
if (! this->m->trailer.isInitialized())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"unable to find trailer while reading xref");
}
int size = this->m->trailer.getKey("/Size").getIntValue();
int max_obj = 0;
if (! this->m->xref_table.empty())
{
max_obj = (*(this->m->xref_table.rbegin())).first.getObj();
}
if (! this->m->deleted_objects.empty())
{
max_obj = std::max(max_obj, *(this->m->deleted_objects.rbegin()));
}
if (size != max_obj + 1)
{
QTC::TC("qpdf", "QPDF xref size mismatch");
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
std::string("reported number of objects (") +
QUtil::int_to_string(size) +
") inconsistent with actual number of objects (" +
QUtil::int_to_string(max_obj + 1) + ")"));
}
// We no longer need the deleted_objects table, so go ahead and
// clear it out to make sure we never depend on its being set.
this->m->deleted_objects.clear();
}
bool
QPDF::parse_xrefFirst(std::string const& line,
int& obj, int& num, int& bytes)
{
// 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))
{
return false;
}
// Gather digits
std::string obj_str;
while (QUtil::is_digit(*p))
{
obj_str.append(1, *p++);
}
// Require space
if (! QUtil::is_space(*p))
{
return false;
}
// Skip spaces
while (QUtil::is_space(*p))
{
++p;
}
// Require digit
if (! QUtil::is_digit(*p))
{
return false;
}
// 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;
}
bytes = p - start;
obj = QUtil::string_to_int(obj_str.c_str());
num = QUtil::string_to_int(num_str.c_str());
return true;
}
bool
QPDF::parse_xrefEntry(std::string const& line,
qpdf_offset_t& f1, int& f2, char& type)
{
// 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();
// 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;
}
// 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;
}
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;
}
// 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;
}
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;
}
if ((f1_str.length() != 10) || (f2_str.length() != 5))
{
QTC::TC("qpdf", "QPDF ignore length error xref entry");
invalid = true;
}
if (invalid)
{
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref table",
this->m->file->getLastOffset(),
"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;
}
qpdf_offset_t
QPDF::read_xrefTable(qpdf_offset_t xref_offset)
{
std::vector<QPDFObjGen> deleted_items;
this->m->file->seek(xref_offset, SEEK_SET);
bool done = false;
while (! done)
{
char linebuf[51];
memset(linebuf, 0, sizeof(linebuf));
this->m->file->read(linebuf, sizeof(linebuf) - 1);
std::string line = linebuf;
int obj = 0;
int num = 0;
int bytes = 0;
if (! parse_xrefFirst(line, obj, num, bytes))
{
QTC::TC("qpdf", "QPDF invalid xref");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref table", this->m->file->getLastOffset(),
"xref syntax invalid");
}
this->m->file->seek(this->m->file->getLastOffset() + bytes, SEEK_SET);
for (int i = obj; i < obj + num; ++i)
{
if (i == 0)
{
// This is needed by checkLinearization()
this->m->first_xref_item_offset = this->m->file->tell();
}
std::string xref_entry = this->m->file->readLine(30);
// For xref_table, these will always be small enough to be ints
qpdf_offset_t f1 = 0;
int f2 = 0;
char type = '\0';
if (! parse_xrefEntry(xref_entry, f1, f2, type))
{
QTC::TC("qpdf", "QPDF invalid xref entry");
throw QPDFExc(
qpdf_e_damaged_pdf, this->m->file->getName(),
"xref table", this->m->file->getLastOffset(),
"invalid xref entry (obj=" +
QUtil::int_to_string(i) + ")");
}
if (type == 'f')
{
// Save deleted items until after we've checked the
// XRefStm, if any.
deleted_items.push_back(QPDFObjGen(i, f2));
}
else
{
insertXrefEntry(i, 1, f1, f2);
}
}
qpdf_offset_t pos = this->m->file->tell();
QPDFTokenizer::Token t = readToken(this->m->file);
if (t == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "trailer"))
{
done = true;
}
else
{
this->m->file->seek(pos, SEEK_SET);
}
}
// Set offset to previous xref table if any
QPDFObjectHandle cur_trailer =
readObject(this->m->file, "trailer", 0, 0, false);
if (! cur_trailer.isDictionary())
{
QTC::TC("qpdf", "QPDF missing trailer");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(),
"expected trailer dictionary");
}
if (! this->m->trailer.isInitialized())
{
setTrailer(cur_trailer);
if (! this->m->trailer.hasKey("/Size"))
{
QTC::TC("qpdf", "QPDF trailer lacks size");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"trailer", this->m->file->getLastOffset(),
"trailer dictionary lacks /Size key");
}
if (! this->m->trailer.getKey("/Size").isInteger())
{
QTC::TC("qpdf", "QPDF trailer size not integer");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"trailer", this->m->file->getLastOffset(),
"/Size key in trailer dictionary is not "
"an integer");
}
}
if (cur_trailer.hasKey("/XRefStm"))
{
if (this->m->ignore_xref_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_xrefStream(
cur_trailer.getKey("/XRefStm").getIntValue());
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"invalid /XRefStm");
}
}
}
// Handle any deleted items now that we've read the /XRefStm.
for (std::vector<QPDFObjGen>::iterator iter = deleted_items.begin();
iter != deleted_items.end(); ++iter)
{
QPDFObjGen& og = *iter;
insertXrefEntry(og.getObj(), 0, 0, og.getGen());
}
if (cur_trailer.hasKey("/Prev"))
{
if (! cur_trailer.getKey("/Prev").isInteger())
{
QTC::TC("qpdf", "QPDF trailer prev not integer");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"trailer", this->m->file->getLastOffset(),
"/Prev key in trailer dictionary is not "
"an integer");
}
QTC::TC("qpdf", "QPDF prev key in trailer dictionary");
xref_offset = cur_trailer.getKey("/Prev").getIntValue();
}
else
{
xref_offset = 0;
}
return xref_offset;
}
qpdf_offset_t
QPDF::read_xrefStream(qpdf_offset_t xref_offset)
{
bool found = false;
if (! this->m->ignore_xref_streams)
{
int xobj;
int xgen;
QPDFObjectHandle xref_obj;
try
{
xref_obj = readObjectAtOffset(
false, xref_offset, "xref stream", -1, 0, xobj, xgen);
}
catch (QPDFExc&)
{
// ignore -- report error below
}
if (xref_obj.isInitialized() &&
xref_obj.isStream() &&
xref_obj.getDict().getKey("/Type").isName() &&
xref_obj.getDict().getKey("/Type").getName() == "/XRef")
{
QTC::TC("qpdf", "QPDF found xref stream");
found = true;
xref_offset = processXRefStream(xref_offset, xref_obj);
}
}
if (! found)
{
QTC::TC("qpdf", "QPDF can't find xref");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", xref_offset, "xref not found");
}
return xref_offset;
}
qpdf_offset_t
QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj)
{
QPDFObjectHandle dict = xref_obj.getDict();
QPDFObjectHandle W_obj = dict.getKey("/W");
QPDFObjectHandle Index_obj = dict.getKey("/Index");
if (! (W_obj.isArray() &&
(W_obj.getArrayNItems() >= 3) &&
W_obj.getArrayItem(0).isInteger() &&
W_obj.getArrayItem(1).isInteger() &&
W_obj.getArrayItem(2).isInteger() &&
dict.getKey("/Size").isInteger() &&
(Index_obj.isArray() || Index_obj.isNull())))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream does not have"
" proper /W and /Index keys");
}
int W[3];
size_t entry_size = 0;
int max_bytes = sizeof(qpdf_offset_t);
for (int i = 0; i < 3; ++i)
{
W[i] = W_obj.getArrayItem(i).getIntValue();
if (W[i] > max_bytes)
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream's /W contains"
" impossibly large values");
}
entry_size += W[i];
}
if (entry_size == 0)
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream's /W indicates"
" entry size of 0");
}
long long max_num_entries =
static_cast<unsigned long long>(-1) / entry_size;
std::vector<long long> indx;
if (Index_obj.isArray())
{
int n_index = Index_obj.getArrayNItems();
if ((n_index % 2) || (n_index < 2))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream's /Index has an"
" invalid number of values");
}
for (int i = 0; i < n_index; ++i)
{
if (Index_obj.getArrayItem(i).isInteger())
{
indx.push_back(Index_obj.getArrayItem(i).getIntValue());
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream's /Index's item " +
QUtil::int_to_string(i) +
" is not an integer");
}
}
QTC::TC("qpdf", "QPDF xref /Index is array",
n_index == 2 ? 0 : 1);
}
else
{
QTC::TC("qpdf", "QPDF xref /Index is null");
long long size = dict.getKey("/Size").getIntValue();
indx.push_back(0);
indx.push_back(size);
}
long long num_entries = 0;
for (unsigned int i = 1; i < indx.size(); i += 2)
{
if (indx.at(i) > max_num_entries - num_entries)
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream claims to contain"
" too many entries: " +
QUtil::int_to_string(indx.at(i)) + " " +
QUtil::int_to_string(max_num_entries) + " " +
QUtil::int_to_string(num_entries));
}
num_entries += indx.at(i);
}
// entry_size and num_entries have both been validated to ensure
// that this multiplication does not cause an overflow.
size_t expected_size = entry_size * num_entries;
PointerHolder<Buffer> bp = xref_obj.getStreamData(qpdf_dl_specialized);
size_t actual_size = bp->getSize();
if (expected_size != actual_size)
{
QPDFExc x(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream data has the wrong size;"
" expected = " + QUtil::int_to_string(expected_size) +
"; actual = " + QUtil::int_to_string(actual_size));
if (expected_size > actual_size)
{
throw x;
}
else
{
warn(x);
}
}
int cur_chunk = 0;
int chunk_count = 0;
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 equal to the size of the buffer.
unsigned char const* data = bp->getBuffer();
for (int i = 0; i < num_entries; ++i)
{
// Read this entry
unsigned char const* entry = data + (entry_size * i);
qpdf_offset_t fields[3];
unsigned char const* p = entry;
for (int j = 0; j < 3; ++j)
{
fields[j] = 0;
if ((j == 0) && (W[0] == 0))
{
QTC::TC("qpdf", "QPDF default for xref stream field 0");
fields[0] = 1;
}
for (int k = 0; k < W[j]; ++k)
{
fields[j] <<= 8;
fields[j] += static_cast<int>(*p++);
}
}
// Get the object and generation number. The object number is
// based on /Index. The generation number is 0 unless this is
// an uncompressed object record, in which case the generation
// number appears as the third field.
int obj = indx.at(cur_chunk) + chunk_count;
++chunk_count;
if (chunk_count >= indx.at(cur_chunk + 1))
{
cur_chunk += 2;
chunk_count = 0;
}
if (saw_first_compressed_object)
{
if (fields[0] != 2)
{
this->m->uncompressed_after_compressed = true;
}
}
else if (fields[0] == 2)
{
saw_first_compressed_object = true;
}
if (obj == 0)
{
// This is needed by checkLinearization()
this->m->first_xref_item_offset = xref_offset;
}
insertXrefEntry(obj, static_cast<int>(fields[0]),
fields[1], static_cast<int>(fields[2]));
}
if (! this->m->trailer.isInitialized())
{
setTrailer(dict);
}
if (dict.hasKey("/Prev"))
{
if (! dict.getKey("/Prev").isInteger())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", this->m->file->getLastOffset(),
"/Prev key in xref stream dictionary is not "
"an integer");
}
QTC::TC("qpdf", "QPDF prev key in xref stream dictionary");
xref_offset = dict.getKey("/Prev").getIntValue();
}
else
{
xref_offset = 0;
}
return xref_offset;
}
void
QPDF::insertXrefEntry(int obj, int f0, qpdf_offset_t f1, int f2, bool overwrite)
{
// 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. Exception: if overwrite is true, then replace any
// existing object. This is used in xref recovery mode, which
// reads the file from beginning to end.
// 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.
{ // private scope
int gen = (f0 == 2 ? 0 : f2);
QPDFObjGen og(obj, gen);
if (this->m->xref_table.count(og))
{
if (overwrite)
{
QTC::TC("qpdf", "QPDF xref overwrite object");
this->m->xref_table.erase(og);
}
else
{
QTC::TC("qpdf", "QPDF xref reused object");
return;
}
}
if (this->m->deleted_objects.count(obj))
{
QTC::TC("qpdf", "QPDF xref deleted object");
return;
}
}
switch (f0)
{
case 0:
this->m->deleted_objects.insert(obj);
break;
case 1:
// f2 is generation
QTC::TC("qpdf", "QPDF xref gen > 0", ((f2 > 0) ? 1 : 0));
this->m->xref_table[QPDFObjGen(obj, f2)] = QPDFXRefEntry(f0, f1, f2);
break;
case 2:
this->m->xref_table[QPDFObjGen(obj, 0)] = QPDFXRefEntry(f0, f1, f2);
break;
default:
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"xref stream", this->m->file->getLastOffset(),
"unknown xref stream entry type " +
QUtil::int_to_string(f0));
break;
}
}
void
QPDF::showXRefTable()
{
for (std::map<QPDFObjGen, QPDFXRefEntry>::iterator iter =
this->m->xref_table.begin();
iter != this->m->xref_table.end(); ++iter)
{
QPDFObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
*this->m->out_stream << og.getObj() << "/" << og.getGen() << ": ";
switch (entry.getType())
{
case 1:
*this->m->out_stream
<< "uncompressed; offset = " << entry.getOffset();
break;
case 2:
*this->m->out_stream
<< "compressed; stream = "
<< entry.getObjStreamNumber()
<< ", index = " << entry.getObjStreamIndex();
break;
default:
throw std::logic_error("unknown cross-reference table type while"
" showing xref_table");
break;
}
*this->m->out_stream << std::endl;
}
}
void
QPDF::fixDanglingReferences(bool force)
{
if (this->m->fixed_dangling_refs && (! force))
{
return;
}
this->m->fixed_dangling_refs = true;
// Create a set of all known indirect objects including those
// we've previously resolved and those that we have created.
std::set<QPDFObjGen> to_process;
for (std::map<QPDFObjGen, ObjCache>::iterator iter =
this->m->obj_cache.begin();
iter != this->m->obj_cache.end(); ++iter)
{
to_process.insert((*iter).first);
}
for (std::map<QPDFObjGen, QPDFXRefEntry>::iterator iter =
this->m->xref_table.begin();
iter != this->m->xref_table.end(); ++iter)
{
to_process.insert((*iter).first);
}
// For each non-scalar item to process, put it in the queue.
std::list<QPDFObjectHandle> queue;
queue.push_back(this->m->trailer);
for (std::set<QPDFObjGen>::iterator iter = to_process.begin();
iter != to_process.end(); ++iter)
{
QPDFObjectHandle obj = QPDFObjectHandle::Factory::newIndirect(
this, (*iter).getObj(), (*iter).getGen());
if (obj.isDictionary() || obj.isArray())
{
queue.push_back(obj);
}
else if (obj.isStream())
{
queue.push_back(obj.getDict());
}
}
// Process the queue by recursively resolving all object
// references. We don't need to do loop detection because we don't
// traverse known indirect objects when processing the queue.
while (! queue.empty())
{
QPDFObjectHandle obj = queue.front();
queue.pop_front();
std::list<QPDFObjectHandle> to_check;
if (obj.isDictionary())
{
std::map<std::string, QPDFObjectHandle> members =
obj.getDictAsMap();
for (std::map<std::string, QPDFObjectHandle>::iterator iter =
members.begin();
iter != members.end(); ++iter)
{
to_check.push_back((*iter).second);
}
}
else if (obj.isArray())
{
std::vector<QPDFObjectHandle> elements = obj.getArrayAsVector();
for (std::vector<QPDFObjectHandle>::iterator iter =
elements.begin();
iter != elements.end(); ++iter)
{
to_check.push_back(*iter);
}
}
for (std::list<QPDFObjectHandle>::iterator iter = to_check.begin();
iter != to_check.end(); ++iter)
{
QPDFObjectHandle sub = *iter;
if (sub.isIndirect())
{
if (sub.getOwningQPDF() == this)
{
QPDFObjGen og(sub.getObjGen());
if (this->m->obj_cache.count(og) == 0)
{
QTC::TC("qpdf", "QPDF detected dangling ref");
queue.push_back(sub);
}
}
}
else
{
queue.push_back(sub);
}
}
}
}
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(0, 0);
if (! this->m->obj_cache.empty())
{
og = (*(this->m->obj_cache.rbegin())).first;
}
return og.getObj();
}
std::vector<QPDFObjectHandle>
QPDF::getAllObjects()
{
// After fixDanglingReferences is called, all objects are in the
// object cache.
fixDanglingReferences(true);
std::vector<QPDFObjectHandle> result;
for (std::map<QPDFObjGen, ObjCache>::iterator iter =
this->m->obj_cache.begin();
iter != this->m->obj_cache.end(); ++iter)
{
QPDFObjGen const& og = (*iter).first;
result.push_back(QPDFObjectHandle::Factory::newIndirect(
this, og.getObj(), og.getGen()));
}
return result;
}
void
QPDF::setLastObjectDescription(std::string const& description,
int objid, int generation)
{
this->m->last_object_description.clear();
if (! description.empty())
{
this->m->last_object_description += description;
if (objid > 0)
{
this->m->last_object_description += ": ";
}
}
if (objid > 0)
{
this->m->last_object_description += "object " +
QUtil::int_to_string(objid) + " " +
QUtil::int_to_string(generation);
}
}
QPDFObjectHandle
QPDF::readObject(PointerHolder<InputSource> input,
std::string const& description,
int objid, int generation, bool in_object_stream)
{
setLastObjectDescription(description, objid, generation);
qpdf_offset_t offset = input->tell();
bool empty = false;
PointerHolder<StringDecrypter> decrypter_ph;
StringDecrypter* decrypter = 0;
if (this->m->encrypted && (! in_object_stream))
{
decrypter_ph = new StringDecrypter(this, objid, generation);
decrypter = decrypter_ph.getPointer();
}
QPDFObjectHandle object = QPDFObjectHandle::parse(
input, this->m->last_object_description,
this->m->tokenizer, empty, decrypter, this);
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(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description,
input->getLastOffset(),
"empty object treated as null"));
}
else if (object.isDictionary() && (! in_object_stream))
{
// check for stream
qpdf_offset_t cur_offset = input->tell();
if (readToken(input) ==
QPDFTokenizer::Token(QPDFTokenizer::tt_word, "stream"))
{
// 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.
{
char ch;
if (input->read(&ch, 1) == 0)
{
// A premature EOF here will result in some
// other problem that will get reported at
// another time.
}
else if (ch == '\n')
{
// ready to read stream data
QTC::TC("qpdf", "QPDF stream with NL only");
}
else if (ch == '\r')
{
// Read another character
if (input->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");
input->unreadCh(ch);
warn(QPDFExc(
qpdf_e_damaged_pdf,
input->getName(),
this->m->last_object_description,
input->tell(),
"stream keyword followed"
" by carriage return only"));
}
}
}
else
{
QTC::TC("qpdf", "QPDF stream without newline");
if (! QUtil::is_space(ch))
{
QTC::TC("qpdf", "QPDF stream with non-space");
input->unreadCh(ch);
}
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description,
input->tell(),
"stream keyword not followed"
" by proper line terminator"));
}
}
// Must get offset before accessing any additional
// objects since resolving a previously unresolved
// indirect object will change file position.
qpdf_offset_t stream_offset = input->tell();
size_t length = 0;
try
{
std::map<std::string, QPDFObjectHandle> dict =
object.getDictAsMap();
if (dict.count("/Length") == 0)
{
QTC::TC("qpdf", "QPDF stream without length");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description, offset,
"stream dictionary lacks /Length key");
}
QPDFObjectHandle length_obj = dict["/Length"];
if (! length_obj.isInteger())
{
QTC::TC("qpdf", "QPDF stream length not integer");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description, offset,
"/Length key in stream dictionary is not "
"an integer");
}
length = length_obj.getIntValue();
input->seek(stream_offset + length, SEEK_SET);
if (! (readToken(input) ==
QPDFTokenizer::Token(
QPDFTokenizer::tt_word, "endstream")))
{
QTC::TC("qpdf", "QPDF missing endstream");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description,
input->getLastOffset(),
"expected endstream");
}
}
catch (QPDFExc& e)
{
if (this->m->attempt_recovery)
{
warn(e);
length = recoverStreamLength(
input, objid, generation, stream_offset);
}
else
{
throw e;
}
}
object = QPDFObjectHandle::Factory::newStream(
this, objid, generation, object, stream_offset, length);
}
else
{
input->seek(cur_offset, SEEK_SET);
}
}
// Override last_offset so that it points to the beginning of the
// object we just read
input->setLastOffset(offset);
return object;
}
bool
QPDF::findEndstream()
{
// Find endstream or endobj. Position the input at that token.
QPDFTokenizer::Token t = readToken(this->m->file, 20);
if ((t.getType() == QPDFTokenizer::tt_word) &&
((t.getValue() == "endobj") ||
(t.getValue() == "endstream")))
{
this->m->file->seek(this->m->file->getLastOffset(), SEEK_SET);
return true;
}
return false;
}
size_t
QPDF::recoverStreamLength(PointerHolder<InputSource> input,
int objid, int generation,
qpdf_offset_t stream_offset)
{
// Try to reconstruct stream length by looking for
// endstream or endobj
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description, stream_offset,
"attempting to recover stream length"));
PatternFinder ef(*this, &QPDF::findEndstream);
size_t length = 0;
if (this->m->file->findFirst("end", stream_offset, 0, ef))
{
length = this->m->file->tell() - stream_offset;
// Reread endstream but, if it was endobj, don't skip that.
QPDFTokenizer::Token t = readToken(this->m->file);
if (t.getValue() == "endobj")
{
this->m->file->seek(this->m->file->getLastOffset(), SEEK_SET);
}
}
if (length)
{
int this_obj_offset = 0;
QPDFObjGen this_obj(0, 0);
// Make sure this is inside this object
for (std::map<QPDFObjGen, QPDFXRefEntry>::iterator iter =
this->m->xref_table.begin();
iter != this->m->xref_table.end(); ++iter)
{
QPDFObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
if (entry.getType() == 1)
{
qpdf_offset_t obj_offset = entry.getOffset();
if ((obj_offset > stream_offset) &&
((this_obj_offset == 0) ||
(this_obj_offset > obj_offset)))
{
this_obj_offset = obj_offset;
this_obj = og;
}
}
}
if (this_obj_offset &&
(this_obj.getObj() == objid) &&
(this_obj.getGen() == generation))
{
// Well, 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");
}
}
if (length == 0)
{
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description, stream_offset,
"unable to recover stream data;"
" treating stream as empty"));
}
else
{
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description, stream_offset,
"recovered stream length: " +
QUtil::int_to_string(length)));
}
QTC::TC("qpdf", "QPDF recovered stream length");
return length;
}
QPDFTokenizer::Token
QPDF::readToken(PointerHolder<InputSource> input, size_t max_len)
{
return this->m->tokenizer.readToken(
input, this->m->last_object_description, true, max_len);
}
QPDFObjectHandle
QPDF::readObjectAtOffset(bool try_recovery,
qpdf_offset_t offset, std::string const& description,
int exp_objid, int exp_generation,
int& objid, int& generation)
{
if (! this->m->attempt_recovery)
{
try_recovery = false;
}
setLastObjectDescription(description, exp_objid, exp_generation);
// 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 to
// ignore these.
if (offset == 0)
{
QTC::TC("qpdf", "QPDF bogus 0 offset", 0);
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description, 0,
"object has offset 0"));
return QPDFObjectHandle::newNull();
}
this->m->file->seek(offset, SEEK_SET);
QPDFTokenizer::Token tobjid = readToken(this->m->file);
QPDFTokenizer::Token tgen = readToken(this->m->file);
QPDFTokenizer::Token tobj = readToken(this->m->file);
bool objidok = (tobjid.getType() == QPDFTokenizer::tt_integer);
int genok = (tgen.getType() == QPDFTokenizer::tt_integer);
int objok = (tobj == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "obj"));
QTC::TC("qpdf", "QPDF check objid", objidok ? 1 : 0);
QTC::TC("qpdf", "QPDF check generation", genok ? 1 : 0);
QTC::TC("qpdf", "QPDF check obj", objok ? 1 : 0);
try
{
if (! (objidok && genok && objok))
{
QTC::TC("qpdf", "QPDF expected n n obj");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description, offset,
"expected n n obj");
}
objid = QUtil::string_to_int(tobjid.getValue().c_str());
generation = QUtil::string_to_int(tgen.getValue().c_str());
if (objid == 0)
{
QTC::TC("qpdf", "QPDF object id 0");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description, offset,
"object with ID 0");
}
if ((exp_objid >= 0) &&
(! ((objid == exp_objid) && (generation == exp_generation))))
{
QTC::TC("qpdf", "QPDF err wrong objid/generation");
QPDFExc e(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description, offset,
std::string("expected ") +
QUtil::int_to_string(exp_objid) + " " +
QUtil::int_to_string(exp_generation) + " 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 ((exp_objid >= 0) && try_recovery)
{
// Try again after reconstructing xref table
reconstruct_xref(e);
QPDFObjGen og(exp_objid, exp_generation);
if (this->m->xref_table.count(og) &&
(this->m->xref_table[og].getType() == 1))
{
qpdf_offset_t new_offset = this->m->xref_table[og].getOffset();
QPDFObjectHandle result = readObjectAtOffset(
false, new_offset, description,
exp_objid, exp_generation, objid, generation);
QTC::TC("qpdf", "QPDF recovered in readObjectAtOffset");
return result;
}
else
{
QTC::TC("qpdf", "QPDF object gone after xref reconstruction");
warn(QPDFExc(
qpdf_e_damaged_pdf, this->m->file->getName(),
"", 0,
std::string(
"object " +
QUtil::int_to_string(exp_objid) +
" " +
QUtil::int_to_string(exp_generation) +
" not found in file after regenerating"
" cross reference table")));
return QPDFObjectHandle::newNull();
}
}
else
{
throw e;
}
}
QPDFObjectHandle oh = readObject(
this->m->file, description, objid, generation, false);
if (! (readToken(this->m->file) ==
QPDFTokenizer::Token(QPDFTokenizer::tt_word, "endobj")))
{
QTC::TC("qpdf", "QPDF err expected endobj");
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description,
this->m->file->getLastOffset(),
"expected endobj"));
}
QPDFObjGen og(objid, generation);
if (! this->m->obj_cache.count(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 = this->m->file->tell();
// skip over spaces
while (true)
{
char ch;
if (this->m->file->read(&ch, 1))
{
if (! isspace(static_cast<unsigned char>(ch)))
{
this->m->file->seek(-1, SEEK_CUR);
break;
}
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description,
this->m->file->tell(),
"EOF after endobj");
}
}
qpdf_offset_t end_after_space = this->m->file->tell();
this->m->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh),
end_before_space, end_after_space);
}
return oh;
}
PointerHolder<QPDFObject>
QPDF::resolve(int objid, int generation)
{
// Check object cache before checking xref table. This allows us
// to insert things into the object cache that don't actually
// exist in the file.
QPDFObjGen og(objid, generation);
if (this->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(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(),
"loop detected resolving object " +
QUtil::int_to_string(objid) + " " +
QUtil::int_to_string(generation)));
return new QPDF_Null;
}
ResolveRecorder rr(this, og);
if ((! this->m->obj_cache.count(og)) && this->m->xref_table.count(og))
{
QPDFXRefEntry const& entry = this->m->xref_table[og];
try
{
switch (entry.getType())
{
case 1:
{
qpdf_offset_t offset = entry.getOffset();
// Object stored in cache by readObjectAtOffset
int aobjid;
int ageneration;
QPDFObjectHandle oh =
readObjectAtOffset(true, offset, "", objid, generation,
aobjid, ageneration);
}
break;
case 2:
resolveObjectsInStream(entry.getObjStreamNumber());
break;
default:
throw QPDFExc(qpdf_e_damaged_pdf,
this->m->file->getName(), "", 0,
"object " +
QUtil::int_to_string(objid) + "/" +
QUtil::int_to_string(generation) +
" has unexpected xref entry type");
}
}
catch (QPDFExc& e)
{
warn(e);
}
catch (std::exception& e)
{
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(), "", 0,
"object " +
QUtil::int_to_string(objid) + "/" +
QUtil::int_to_string(generation) +
": error reading object: " + e.what()));
}
}
if (this->m->obj_cache.count(og) == 0)
{
// PDF spec says unknown objects resolve to the null object.
QTC::TC("qpdf", "QPDF resolve failure to null");
QPDFObjectHandle oh = QPDFObjectHandle::newNull();
this->m->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
}
PointerHolder<QPDFObject> result(this->m->obj_cache[og].object);
if (! result->hasDescription())
{
result->setDescription(
this,
"object " + QUtil::int_to_string(objid) + " " +
QUtil::int_to_string(generation));
}
return result;
}
void
QPDF::resolveObjectsInStream(int obj_stream_number)
{
// Force resolution of object stream
QPDFObjectHandle obj_stream = getObjectByID(obj_stream_number, 0);
if (! obj_stream.isStream())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description,
this->m->file->getLastOffset(),
"supposed object stream " +
QUtil::int_to_string(obj_stream_number) +
" is not a stream");
}
// For linearization data in the object, use the data from the
// object stream for the objects in the stream.
QPDFObjGen stream_og(obj_stream_number, 0);
qpdf_offset_t end_before_space =
this->m->obj_cache[stream_og].end_before_space;
qpdf_offset_t end_after_space =
this->m->obj_cache[stream_og].end_after_space;
QPDFObjectHandle dict = obj_stream.getDict();
if (! (dict.getKey("/Type").isName() &&
dict.getKey("/Type").getName() == "/ObjStm"))
{
QTC::TC("qpdf", "QPDF ERR object stream with wrong type");
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description,
this->m->file->getLastOffset(),
"supposed object stream " +
QUtil::int_to_string(obj_stream_number) +
" has wrong type");
}
if (! (dict.getKey("/N").isInteger() &&
dict.getKey("/First").isInteger()))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
this->m->last_object_description,
this->m->file->getLastOffset(),
"object stream " +
QUtil::int_to_string(obj_stream_number) +
" has incorrect keys");
}
int n = dict.getKey("/N").getIntValue();
int first = dict.getKey("/First").getIntValue();
std::map<int, int> offsets;
PointerHolder<Buffer> bp = obj_stream.getStreamData(qpdf_dl_specialized);
PointerHolder<InputSource> input = new BufferInputSource(
this->m->file->getName() +
" object stream " + QUtil::int_to_string(obj_stream_number),
bp.getPointer());
for (int i = 0; i < n; ++i)
{
QPDFTokenizer::Token tnum = readToken(input);
QPDFTokenizer::Token toffset = readToken(input);
if (! ((tnum.getType() == QPDFTokenizer::tt_integer) &&
(toffset.getType() == QPDFTokenizer::tt_integer)))
{
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->m->last_object_description,
input->getLastOffset(),
"expected integer in object stream header");
}
int num = QUtil::string_to_int(tnum.getValue().c_str());
int offset = QUtil::string_to_ll(toffset.getValue().c_str());
offsets[num] = 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.
for (std::map<int, int>::iterator iter = offsets.begin();
iter != offsets.end(); ++iter)
{
int obj = (*iter).first;
QPDFObjGen og(obj, 0);
QPDFXRefEntry const& entry = this->m->xref_table[og];
if ((entry.getType() == 2) &&
(entry.getObjStreamNumber() == obj_stream_number))
{
int offset = (*iter).second;
input->seek(offset, SEEK_SET);
QPDFObjectHandle oh = readObject(input, "", obj, 0, true);
this->m->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh),
end_before_space, end_after_space);
}
else
{
QTC::TC("qpdf", "QPDF not caching overridden objstm object");
}
}
}
QPDFObjectHandle
QPDF::makeIndirectObject(QPDFObjectHandle oh)
{
int max_objid = getObjectCount();
QPDFObjGen next(max_objid + 1, 0);
this->m->obj_cache[next] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
return QPDFObjectHandle::Factory::newIndirect(
this, next.getObj(), next.getGen());
}
QPDFObjectHandle
QPDF::getObjectByObjGen(QPDFObjGen const& og)
{
return getObjectByID(og.getObj(), og.getGen());
}
QPDFObjectHandle
QPDF::getObjectByID(int objid, int generation)
{
return QPDFObjectHandle::Factory::newIndirect(this, objid, generation);
}
void
QPDF::replaceObject(QPDFObjGen const& og, QPDFObjectHandle oh)
{
replaceObject(og.getObj(), og.getGen(), oh);
}
void
QPDF::replaceObject(int objid, int generation, QPDFObjectHandle oh)
{
if (oh.isIndirect())
{
QTC::TC("qpdf", "QPDF replaceObject called with indirect object");
throw std::logic_error(
"QPDF::replaceObject called with indirect object handle");
}
// Force new object to appear in the cache
resolve(objid, generation);
// Replace the object in the object cache
QPDFObjGen og(objid, generation);
this->m->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
}
void
QPDF::replaceReserved(QPDFObjectHandle reserved,
QPDFObjectHandle replacement)
{
QTC::TC("qpdf", "QPDF replaceReserved");
reserved.assertReserved();
replaceObject(reserved.getObjGen(), replacement);
}
QPDFObjectHandle
QPDF::copyForeignObject(QPDFObjectHandle foreign)
{
return copyForeignObject(foreign, false);
}
QPDFObjectHandle
QPDF::copyForeignObject(QPDFObjectHandle foreign, bool allow_page)
{
if (! foreign.isIndirect())
{
QTC::TC("qpdf", "QPDF copyForeign direct");
throw std::logic_error(
"QPDF::copyForeign called with direct object handle");
}
QPDF* other = foreign.getOwningQPDF();
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 = this->m->object_copiers[other];
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 (std::vector<QPDFObjectHandle>::iterator iter =
obj_copier.to_copy.begin();
iter != obj_copier.to_copy.end(); ++iter)
{
QPDFObjectHandle& to_copy = *iter;
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();
return obj_copier.object_map[foreign.getObjGen()];
}
void
QPDF::reserveObjects(QPDFObjectHandle foreign, ObjCopier& obj_copier,
bool top)
{
if (foreign.isReserved())
{
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 ((! top) && foreign.isPageObject())
{
QTC::TC("qpdf", "QPDF not crossing page boundary");
return;
}
if (foreign.isIndirect())
{
QPDFObjGen foreign_og(foreign.getObjGen());
if (obj_copier.visiting.find(foreign_og) != obj_copier.visiting.end())
{
QTC::TC("qpdf", "QPDF loop reserving objects");
return;
}
if (obj_copier.object_map.find(foreign_og) !=
obj_copier.object_map.end())
{
QTC::TC("qpdf", "QPDF already reserved object");
return;
}
QTC::TC("qpdf", "QPDF copy indirect");
obj_copier.visiting.insert(foreign_og);
std::map<QPDFObjGen, QPDFObjectHandle>::iterator mapping =
obj_copier.object_map.find(foreign_og);
if (mapping == obj_copier.object_map.end())
{
obj_copier.to_copy.push_back(foreign);
QPDFObjectHandle reservation;
if (foreign.isStream())
{
reservation = QPDFObjectHandle::newStream(this);
}
else
{
reservation = QPDFObjectHandle::newReserved(this);
}
obj_copier.object_map[foreign_og] = reservation;
}
}
if (foreign.isArray())
{
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.isDictionary())
{
QTC::TC("qpdf", "QPDF reserve dictionary");
std::set<std::string> keys = foreign.getKeys();
for (std::set<std::string>::iterator iter = keys.begin();
iter != keys.end(); ++iter)
{
reserveObjects(foreign.getKey(*iter), obj_copier, false);
}
}
else if (foreign.isStream())
{
QTC::TC("qpdf", "QPDF reserve stream");
reserveObjects(foreign.getDict(), obj_copier, false);
}
if (foreign.isIndirect())
{
QPDFObjGen foreign_og(foreign.getObjGen());
obj_copier.visiting.erase(foreign_og);
}
}
QPDFObjectHandle
QPDF::replaceForeignIndirectObjects(
QPDFObjectHandle foreign, ObjCopier& obj_copier, bool top)
{
QPDFObjectHandle result;
if ((! top) && foreign.isIndirect())
{
QTC::TC("qpdf", "QPDF replace indirect");
QPDFObjGen foreign_og(foreign.getObjGen());
std::map<QPDFObjGen, QPDFObjectHandle>::iterator mapping =
obj_copier.object_map.find(foreign_og);
if (mapping == obj_copier.object_map.end())
{
// This case would occur if this is a reference to a Page
// or Pages object that we didn't traverse into.
QTC::TC("qpdf", "QPDF replace foreign indirect with null");
result = QPDFObjectHandle::newNull();
}
else
{
result = obj_copier.object_map[foreign_og];
}
}
else if (foreign.isArray())
{
QTC::TC("qpdf", "QPDF replace array");
result = QPDFObjectHandle::newArray();
int n = foreign.getArrayNItems();
for (int i = 0; i < n; ++i)
{
result.appendItem(
replaceForeignIndirectObjects(
foreign.getArrayItem(i), obj_copier, false));
}
}
else if (foreign.isDictionary())
{
QTC::TC("qpdf", "QPDF replace dictionary");
result = QPDFObjectHandle::newDictionary();
std::set<std::string> keys = foreign.getKeys();
for (std::set<std::string>::iterator iter = keys.begin();
iter != keys.end(); ++iter)
{
result.replaceKey(
*iter,
replaceForeignIndirectObjects(
foreign.getKey(*iter), obj_copier, false));
}
}
else if (foreign.isStream())
{
QTC::TC("qpdf", "QPDF replace stream");
QPDFObjGen foreign_og(foreign.getObjGen());
result = obj_copier.object_map[foreign_og];
result.assertStream();
QPDFObjectHandle dict = result.getDict();
QPDFObjectHandle old_dict = foreign.getDict();
std::set<std::string> keys = old_dict.getKeys();
for (std::set<std::string>::iterator iter = keys.begin();
iter != keys.end(); ++iter)
{
dict.replaceKey(
*iter,
replaceForeignIndirectObjects(
old_dict.getKey(*iter), obj_copier, false));
}
if (this->m->copied_stream_data_provider == 0)
{
this->m->copied_stream_data_provider =
new CopiedStreamDataProvider();
this->m->copied_streams = this->m->copied_stream_data_provider;
}
QPDFObjGen local_og(result.getObjGen());
this->m->copied_stream_data_provider->registerForeignStream(
local_og, foreign);
result.replaceStreamData(this->m->copied_streams,
dict.getKey("/Filter"),
dict.getKey("/DecodeParms"));
}
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::swapObjects(QPDFObjGen const& og1, QPDFObjGen const& og2)
{
swapObjects(og1.getObj(), og1.getGen(), og2.getObj(), og2.getGen());
}
void
QPDF::swapObjects(int objid1, int generation1, int objid2, int generation2)
{
// Force objects to be loaded into cache; then swap them in the
// cache.
resolve(objid1, generation1);
resolve(objid2, generation2);
QPDFObjGen og1(objid1, generation1);
QPDFObjGen og2(objid2, generation2);
ObjCache t = this->m->obj_cache[og1];
this->m->obj_cache[og1] = this->m->obj_cache[og2];
this->m->obj_cache[og2] = t;
}
std::string
QPDF::getFilename() const
{
return this->m->file->getName();
}
std::string
QPDF::getPDFVersion() const
{
return this->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.getIntValue();
}
}
}
}
return result;
}
QPDFObjectHandle
QPDF::getTrailer()
{
return this->m->trailer;
}
QPDFObjectHandle
QPDF::getRoot()
{
QPDFObjectHandle root = this->m->trailer.getKey("/Root");
if (! root.isDictionary())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(),
"unable to find /Root dictionary");
}
return root;
}
void
QPDF::getObjectStreamData(std::map<int, int>& omap)
{
for (std::map<QPDFObjGen, QPDFXRefEntry>::iterator iter =
this->m->xref_table.begin();
iter != this->m->xref_table.end(); ++iter)
{
QPDFObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
if (entry.getType() == 2)
{
omap[og.getObj()] = entry.getObjStreamNumber();
}
}
}
std::vector<QPDFObjGen>
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 =
this->m->trailer.getKey("/Encrypt");
QPDFObjGen encryption_dict_og = encryption_dict.getObjGen();
std::set<QPDFObjGen> visited;
std::list<QPDFObjectHandle> queue;
queue.push_front(this->m->trailer);
std::vector<QPDFObjGen> result;
while (! queue.empty())
{
QPDFObjectHandle obj = queue.front();
queue.pop_front();
if (obj.isIndirect())
{
QPDFObjGen og = obj.getObjGen();
if (visited.count(og))
{
QTC::TC("qpdf", "QPDF loop detected traversing objects");
continue;
}
if (og == encryption_dict_og)
{
QTC::TC("qpdf", "QPDF exclude encryption dictionary");
}
else if (! obj.isStream())
{
result.push_back(og);
}
visited.insert(og);
}
if (obj.isStream())
{
QPDFObjectHandle dict = obj.getDict();
std::set<std::string> keys = dict.getKeys();
for (std::set<std::string>::reverse_iterator 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_front(value);
}
}
}
else if (obj.isDictionary())
{
std::set<std::string> keys = obj.getKeys();
for (std::set<std::string>::reverse_iterator iter = keys.rbegin();
iter != keys.rend(); ++iter)
{
queue.push_front(obj.getKey(*iter));
}
}
else if (obj.isArray())
{
int n = obj.getArrayNItems();
for (int i = 1; i <= n; ++i)
{
queue.push_front(obj.getArrayItem(n - i));
}
}
}
return result;
}
bool
QPDF::pipeStreamData(int objid, int generation,
qpdf_offset_t offset, size_t length,
QPDFObjectHandle stream_dict,
Pipeline* pipeline,
bool suppress_warnings,
bool will_retry)
{
bool success = false;
std::vector<PointerHolder<Pipeline> > to_delete;
if (this->m->encrypted)
{
decryptStream(pipeline, objid, generation, stream_dict, to_delete);
}
try
{
this->m->file->seek(offset, SEEK_SET);
char buf[10240];
while (length > 0)
{
size_t to_read = (sizeof(buf) < length ? sizeof(buf) : length);
size_t len = this->m->file->read(buf, to_read);
if (len == 0)
{
throw QPDFExc(qpdf_e_damaged_pdf,
this->m->file->getName(),
this->m->last_object_description,
this->m->file->getLastOffset(),
"unexpected EOF reading stream data");
}
length -= len;
pipeline->write(QUtil::unsigned_char_pointer(buf), len);
}
pipeline->finish();
success = true;
}
catch (QPDFExc& e)
{
if (! suppress_warnings)
{
warn(e);
}
}
catch (std::exception& e)
{
if (! suppress_warnings)
{
QTC::TC("qpdf", "QPDF decoding error warning");
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(),
"error decoding stream data for object " +
QUtil::int_to_string(objid) + " " +
QUtil::int_to_string(generation) + ": " + e.what()));
if (will_retry)
{
warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(),
"stream will be re-processed without"
" filtering to avoid data loss"));
}
}
}
if (! success)
{
try
{
pipeline->finish();
}
catch (std::exception&)
{
// ignore
}
}
return success;
}
void
QPDF::findAttachmentStreams()
{
QPDFObjectHandle root = getRoot();
QPDFObjectHandle names = root.getKey("/Names");
if (! names.isDictionary())
{
return;
}
QPDFObjectHandle embeddedFiles = names.getKey("/EmbeddedFiles");
if (! embeddedFiles.isDictionary())
{
return;
}
names = embeddedFiles.getKey("/Names");
if (! names.isArray())
{
return;
}
for (int i = 0; i < names.getArrayNItems(); ++i)
{
QPDFObjectHandle item = names.getArrayItem(i);
if (item.isDictionary() &&
item.getKey("/Type").isName() &&
(item.getKey("/Type").getName() == "/Filespec") &&
item.getKey("/EF").isDictionary() &&
item.getKey("/EF").getKey("/F").isStream())
{
QPDFObjectHandle stream = item.getKey("/EF").getKey("/F");
this->m->attachment_streams.insert(stream.getObjGen());
}
}
}
void
QPDF::stopOnError(std::string const& message)
{
// 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.
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"", this->m->file->getLastOffset(), message);
}
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