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qpdf/libqpdf/QPDF.cc

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#include <qpdf/QPDF.hh>
#include <vector>
#include <map>
#include <string.h>
#include <memory.h>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/PCRE.hh>
#include <qpdf/Pipeline.hh>
#include <qpdf/Pl_Discard.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/QPDF_Null.hh>
#include <qpdf/QPDF_Dictionary.hh>
std::string QPDF::qpdf_version = "2.3.1";
void
QPDF::InputSource::setLastOffset(off_t offset)
{
this->last_offset = offset;
}
off_t
QPDF::InputSource::getLastOffset() const
{
return this->last_offset;
}
std::string
QPDF::InputSource::readLine()
{
// Read a line terminated by one or more \r or \n characters
// without caring what the exact terminator is. Consume the
// trailing newline characters but don't return them.
off_t offset = this->tell();
std::string buf;
enum { st_before_nl, st_at_nl } state = st_before_nl;
char ch;
while (1)
{
size_t len = this->read(&ch, 1);
if (len == 0)
{
break;
}
if (state == st_before_nl)
{
if ((ch == '\012') || (ch == '\015'))
{
state = st_at_nl;
}
else
{
buf += ch;
}
}
else if (state == st_at_nl)
{
if ((ch == '\012') || (ch == '\015'))
{
// do nothing
}
else
{
// unread this character
this->unreadCh(ch);
break;
}
}
}
// Override last offset to be where we started this line rather
// than before the last character read
this->last_offset = offset;
return buf;
}
QPDF::FileInputSource::FileInputSource() :
file(0)
{
}
void
QPDF::FileInputSource::setFilename(char const* filename)
{
destroy();
this->filename = filename;
this->file = QUtil::fopen_wrapper(std::string("open ") + this->filename,
fopen(this->filename.c_str(), "rb"));
}
QPDF::FileInputSource::~FileInputSource()
{
destroy();
}
void
QPDF::FileInputSource::destroy()
{
if (this->file)
{
fclose(this->file);
this->file = 0;
}
}
std::string const&
QPDF::FileInputSource::getName() const
{
return this->filename;
}
off_t
QPDF::FileInputSource::tell()
{
return QUtil::ftell_off_t(this->file);
}
void
QPDF::FileInputSource::seek(off_t offset, int whence)
{
QUtil::os_wrapper(std::string("seek to ") + this->filename + ", offset " +
QUtil::int_to_string(offset) + " (" +
QUtil::int_to_string(whence) + ")",
QUtil::fseek_off_t(this->file, offset, whence));
}
void
QPDF::FileInputSource::rewind()
{
::rewind(this->file);
}
size_t
QPDF::FileInputSource::read(char* buffer, size_t length)
{
this->last_offset = QUtil::ftell_off_t(this->file);
size_t len = fread(buffer, 1, length, this->file);
if ((len == 0) && ferror(this->file))
{
throw QPDFExc(qpdf_e_system,
this->filename, "",
this->last_offset,
std::string("read ") +
QUtil::int_to_string(length) + " bytes");
}
return len;
}
void
QPDF::FileInputSource::unreadCh(char ch)
{
QUtil::os_wrapper(this->filename + ": unread character",
ungetc((unsigned char)ch, this->file));
}
QPDF::BufferInputSource::BufferInputSource(std::string const& description,
Buffer* buf, bool own_memory) :
own_memory(own_memory),
description(description),
buf(buf),
cur_offset(0)
{
}
QPDF::BufferInputSource::~BufferInputSource()
{
if (own_memory)
{
delete this->buf;
}
}
std::string const&
QPDF::BufferInputSource::getName() const
{
return this->description;
}
off_t
QPDF::BufferInputSource::tell()
{
return this->cur_offset;
}
void
QPDF::BufferInputSource::seek(off_t offset, int whence)
{
switch (whence)
{
case SEEK_SET:
this->cur_offset = offset;
break;
case SEEK_END:
this->cur_offset = (off_t)this->buf->getSize() + offset;
break;
case SEEK_CUR:
this->cur_offset += offset;
break;
default:
throw std::logic_error(
"INTERNAL ERROR: invalid argument to BufferInputSource::seek");
break;
}
}
void
QPDF::BufferInputSource::rewind()
{
this->cur_offset = 0;
}
size_t
QPDF::BufferInputSource::read(char* buffer, size_t length)
{
off_t end_pos = (off_t) this->buf->getSize();
if (this->cur_offset >= end_pos)
{
this->last_offset = end_pos;
return 0;
}
this->last_offset = this->cur_offset;
size_t len = std::min((size_t)(end_pos - this->cur_offset), length);
memcpy(buffer, buf->getBuffer() + this->cur_offset, len);
this->cur_offset += len;
return len;
}
void
QPDF::BufferInputSource::unreadCh(char ch)
{
if (this->cur_offset > 0)
{
--this->cur_offset;
}
}
QPDF::ObjGen::ObjGen(int o = 0, int g = 0) :
obj(o),
gen(g)
{
}
bool
QPDF::ObjGen::operator<(ObjGen const& rhs) const
{
return ((this->obj < rhs.obj) ||
((this->obj == rhs.obj) && (this->gen < rhs.gen)));
}
std::string const&
QPDF::QPDFVersion()
{
return QPDF::qpdf_version;
}
QPDF::QPDF() :
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),
encrypt_metadata(true),
cf_stream(e_none),
cf_string(e_none),
cf_file(e_none),
cached_key_objid(0),
cached_key_generation(0),
first_xref_item_offset(0),
uncompressed_after_compressed(false)
{
}
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->xref_table.clear();
for (std::map<ObjGen, ObjCache>::iterator iter = this->obj_cache.begin();
iter != obj_cache.end(); ++iter)
{
QPDFObject::ObjAccessor::releaseResolved(
(*iter).second.object.getPointer());
}
}
void
QPDF::processFile(char const* filename, char const* password)
{
FileInputSource* fi = new FileInputSource();
this->file = fi;
fi->setFilename(filename);
parse(password);
}
void
QPDF::processMemoryFile(char const* description,
char const* buf, size_t length,
char const* password)
{
this->file =
new BufferInputSource(description,
new Buffer((unsigned char*)buf, length),
true);
parse(password);
}
void
QPDF::setIgnoreXRefStreams(bool val)
{
this->ignore_xref_streams = val;
}
void
QPDF::setOutputStreams(std::ostream* out, std::ostream* err)
{
this->out_stream = out ? out : &std::cout;
this->err_stream = err ? err : &std::cerr;
}
void
QPDF::setSuppressWarnings(bool val)
{
this->suppress_warnings = val;
}
void
QPDF::setAttemptRecovery(bool val)
{
this->attempt_recovery = val;
}
std::vector<QPDFExc>
QPDF::getWarnings()
{
std::vector<QPDFExc> result = this->warnings;
this->warnings.clear();
return result;
}
void
QPDF::parse(char const* password)
{
PCRE header_re("^%PDF-(1.\\d+)\\b");
PCRE eof_re("(?s:startxref\\s+(\\d+)\\s+%%EOF\\b)");
if (password)
{
this->provided_password = password;
}
std::string line = this->file->readLine();
PCRE::Match m1 = header_re.match(line.c_str());
if (m1)
{
this->pdf_version = m1.getMatch(1);
if (atof(this->pdf_version.c_str()) < 1.2)
{
this->tokenizer.allowPoundAnywhereInName();
}
}
else
{
QTC::TC("qpdf", "QPDF not a pdf file");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"", 0, "not a PDF file");
}
// 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.
static int const tbuf_size = 1054;
this->file->seek(0, SEEK_END);
if (this->file->tell() > tbuf_size)
{
this->file->seek(-tbuf_size, SEEK_END);
}
else
{
this->file->rewind();
}
char* buf = new char[tbuf_size + 1];
// Put buf in an array-style PointerHolder to guarantee deletion
// of buf.
PointerHolder<char> b(true, buf);
memset(buf, '\0', tbuf_size + 1);
this->file->read(buf, tbuf_size);
// Since buf may contain null characters, we can't do a regexp
// search on buf directly. Find the last occurrence within buf
// where the regexp matches.
char* p = buf;
char const* candidate = "";
while ((p = (char*)memchr(p, 's', tbuf_size - (p - buf))) != 0)
{
if (eof_re.match(p))
{
candidate = p;
}
++p;
}
try
{
PCRE::Match m2 = eof_re.match(candidate);
if (! m2)
{
QTC::TC("qpdf", "QPDF can't find startxref");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(), "", 0,
"can't find startxref");
}
off_t xref_offset = atol(m2.getMatch(1).c_str());
read_xref(xref_offset);
}
catch (QPDFExc& e)
{
if (this->attempt_recovery)
{
reconstruct_xref(e);
QTC::TC("qpdf", "QPDF reconstructed xref table");
}
else
{
throw e;
}
}
initializeEncryption();
}
void
QPDF::warn(QPDFExc const& e)
{
this->warnings.push_back(e);
if (! this->suppress_warnings)
{
*err_stream << "WARNING: "
<< this->warnings.back().what() << std::endl;
}
}
void
QPDF::setTrailer(QPDFObjectHandle obj)
{
if (this->trailer.isInitialized())
{
return;
}
this->trailer = obj;
}
void
QPDF::reconstruct_xref(QPDFExc& e)
{
PCRE obj_re("^\\s*(\\d+)\\s+(\\d+)\\s+obj\\b");
PCRE endobj_re("^\\s*endobj\\b");
PCRE trailer_re("^\\s*trailer\\b");
warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(), "", 0,
"file is damaged"));
warn(e);
warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(), "", 0,
"Attempting to reconstruct cross-reference table"));
// Delete all references to type 1 (uncompressed) objects
std::set<ObjGen> to_delete;
for (std::map<ObjGen, QPDFXRefEntry>::iterator iter =
this->xref_table.begin();
iter != this->xref_table.end(); ++iter)
{
if (((*iter).second).getType() == 1)
{
to_delete.insert((*iter).first);
}
}
for (std::set<ObjGen>::iterator iter = to_delete.begin();
iter != to_delete.end(); ++iter)
{
this->xref_table.erase(*iter);
}
this->file->seek(0, SEEK_END);
off_t eof = this->file->tell();
this->file->seek(0, SEEK_SET);
bool in_obj = false;
while (this->file->tell() < eof)
{
std::string line = this->file->readLine();
if (in_obj)
{
if (endobj_re.match(line.c_str()))
{
in_obj = false;
}
}
else
{
PCRE::Match m = obj_re.match(line.c_str());
if (m)
{
in_obj = true;
int obj = atoi(m.getMatch(1).c_str());
int gen = atoi(m.getMatch(2).c_str());
int offset = this->file->getLastOffset();
insertXrefEntry(obj, 1, offset, gen, true);
}
else if ((! this->trailer.isInitialized()) &&
trailer_re.match(line.c_str()))
{
// read "trailer"
this->file->seek(this->file->getLastOffset(), SEEK_SET);
readToken(this->file);
QPDFObjectHandle t =
readObject(this->file, "trailer", 0, 0, false);
if (! t.isDictionary())
{
// Oh well. It was worth a try.
}
else
{
setTrailer(t);
}
}
}
}
if (! this->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->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(off_t xref_offset)
{
std::map<int, int> free_table;
while (xref_offset)
{
this->file->seek(xref_offset, SEEK_SET);
std::string line = this->file->readLine();
if (line == "xref")
{
xref_offset = read_xrefTable(this->file->tell());
}
else
{
xref_offset = read_xrefStream(xref_offset);
}
}
int size = this->trailer.getKey("/Size").getIntValue();
int max_obj = 0;
if (! xref_table.empty())
{
max_obj = (*(xref_table.rbegin())).first.obj;
}
if (! this->deleted_objects.empty())
{
max_obj = std::max(max_obj, *(this->deleted_objects.rbegin()));
}
if (size != max_obj + 1)
{
QTC::TC("qpdf", "QPDF xref size mismatch");
warn(QPDFExc(qpdf_e_damaged_pdf, this->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->deleted_objects.clear();
}
int
QPDF::read_xrefTable(off_t xref_offset)
{
PCRE xref_first_re("^\\s*(\\d+)\\s+(\\d+)");
PCRE xref_entry_re("(?s:(^\\d{10}) (\\d{5}) ([fn])[ \r\n]{2}$)");
std::vector<ObjGen> deleted_items;
this->file->seek(xref_offset, SEEK_SET);
bool done = false;
while (! done)
{
std::string line = this->file->readLine();
PCRE::Match m1 = xref_first_re.match(line.c_str());
if (! m1)
{
QTC::TC("qpdf", "QPDF invalid xref");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"xref table", this->file->getLastOffset(),
"xref syntax invalid");
}
int obj = atoi(m1.getMatch(1).c_str());
int num = atoi(m1.getMatch(2).c_str());
static int const xref_entry_size = 20;
char xref_entry[xref_entry_size + 1];
for (int i = obj; i < obj + num; ++i)
{
if (i == 0)
{
// This is needed by checkLinearization()
this->first_xref_item_offset = this->file->tell();
}
memset(xref_entry, 0, sizeof(xref_entry));
this->file->read(xref_entry, xref_entry_size);
PCRE::Match m2 = xref_entry_re.match(xref_entry);
if (! m2)
{
QTC::TC("qpdf", "QPDF invalid xref entry");
throw QPDFExc(
qpdf_e_damaged_pdf, this->file->getName(),
"xref table", this->file->getLastOffset(),
"invalid xref entry (obj=" +
QUtil::int_to_string(i) + ")");
}
int f1 = atoi(m2.getMatch(1).c_str());
int f2 = atoi(m2.getMatch(2).c_str());
char type = m2.getMatch(3)[0];
if (type == 'f')
{
// Save deleted items until after we've checked the
// XRefStm, if any.
deleted_items.push_back(ObjGen(i, f2));
}
else
{
insertXrefEntry(i, 1, f1, f2);
}
}
off_t pos = this->file->tell();
QPDFTokenizer::Token t = readToken(this->file);
if (t == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "trailer"))
{
done = true;
}
else
{
this->file->seek(pos, SEEK_SET);
}
}
// Set offset to previous xref table if any
QPDFObjectHandle cur_trailer =
readObject(this->file, "trailer", 0, 0, false);
if (! cur_trailer.isDictionary())
{
QTC::TC("qpdf", "QPDF missing trailer");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"", this->file->getLastOffset(),
"expected trailer dictionary");
}
if (! this->trailer.isInitialized())
{
setTrailer(cur_trailer);
if (! this->trailer.hasKey("/Size"))
{
QTC::TC("qpdf", "QPDF trailer lacks size");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"trailer", this->file->getLastOffset(),
"trailer dictionary lacks /Size key");
}
if (! this->trailer.getKey("/Size").isInteger())
{
QTC::TC("qpdf", "QPDF trailer size not integer");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"trailer", this->file->getLastOffset(),
"/Size key in trailer dictionary is not "
"an integer");
}
}
if (cur_trailer.hasKey("/XRefStm"))
{
if (this->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->file->getName(),
"xref stream", xref_offset,
"invalid /XRefStm");
}
}
}
// Handle any deleted items now that we've read the /XRefStm.
for (std::vector<ObjGen>::iterator iter = deleted_items.begin();
iter != deleted_items.end(); ++iter)
{
ObjGen& og = *iter;
insertXrefEntry(og.obj, 0, 0, og.gen);
}
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->file->getName(),
"trailer", this->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;
}
int
QPDF::read_xrefStream(off_t xref_offset)
{
bool found = false;
if (! this->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& e)
{
// 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->file->getName(),
"", xref_offset, "xref not found");
}
return xref_offset;
}
int
QPDF::processXRefStream(off_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->file->getName(),
"xref stream", xref_offset,
"Cross-reference stream does not have"
" proper /W and /Index keys");
}
std::vector<int> 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->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->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");
int size = dict.getKey("/Size").getIntValue();
indx.push_back(0);
indx.push_back(size);
}
int num_entries = 0;
for (unsigned int i = 1; i < indx.size(); i += 2)
{
num_entries += indx[i];
}
int W[3];
int entry_size = 0;
for (int i = 0; i < 3; ++i)
{
W[i] = W_obj.getArrayItem(i).getIntValue();
entry_size += W[i];
}
size_t expected_size = entry_size * num_entries;
PointerHolder<Buffer> bp = xref_obj.getStreamData();
size_t actual_size = bp->getSize();
if (expected_size != actual_size)
{
QPDFExc x(qpdf_e_damaged_pdf, this->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;
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);
int 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] += (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[cur_chunk] + chunk_count;
++chunk_count;
if (chunk_count >= indx[cur_chunk + 1])
{
cur_chunk += 2;
chunk_count = 0;
}
if (saw_first_compressed_object)
{
if (fields[0] != 2)
{
this->uncompressed_after_compressed = true;
}
}
else if (fields[0] == 2)
{
saw_first_compressed_object = true;
}
if (obj == 0)
{
// This is needed by checkLinearization()
this->first_xref_item_offset = xref_offset;
}
insertXrefEntry(obj, fields[0], fields[1], fields[2]);
}
if (! this->trailer.isInitialized())
{
setTrailer(dict);
}
if (dict.hasKey("/Prev"))
{
if (! dict.getKey("/Prev").isInteger())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"xref stream", this->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, int 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);
ObjGen og(obj, gen);
if (this->xref_table.count(og))
{
if (overwrite)
{
QTC::TC("qpdf", "QPDF xref overwrite object");
this->xref_table.erase(og);
}
else
{
QTC::TC("qpdf", "QPDF xref reused object");
return;
}
}
if (this->deleted_objects.count(obj))
{
QTC::TC("qpdf", "QPDF xref deleted object");
return;
}
}
switch (f0)
{
case 0:
this->deleted_objects.insert(obj);
break;
case 1:
// f2 is generation
QTC::TC("qpdf", "QPDF xref gen > 0", ((f2 > 0) ? 1 : 0));
this->xref_table[ObjGen(obj, f2)] = QPDFXRefEntry(f0, f1, f2);
break;
case 2:
this->xref_table[ObjGen(obj, 0)] = QPDFXRefEntry(f0, f1, f2);
break;
default:
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"xref stream", this->file->getLastOffset(),
"unknown xref stream entry type " +
QUtil::int_to_string(f0));
break;
}
}
void
QPDF::showXRefTable()
{
for (std::map<ObjGen, QPDFXRefEntry>::iterator iter =
this->xref_table.begin();
iter != this->xref_table.end(); ++iter)
{
ObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
*out_stream << og.obj << "/" << og.gen << ": ";
switch (entry.getType())
{
case 1:
*out_stream << "uncompressed; offset = " << entry.getOffset();
break;
case 2:
*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;
}
*out_stream << std::endl;
}
}
void
QPDF::setLastObjectDescription(std::string const& description,
int objid, int generation)
{
this->last_object_description.clear();
if (! description.empty())
{
this->last_object_description += description;
if (objid > 0)
{
this->last_object_description += ": ";
}
}
if (objid > 0)
{
this->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);
off_t offset = input->tell();
QPDFObjectHandle object = readObjectInternal(
input, objid, generation, in_object_stream, false, false);
// Override last_offset so that it points to the beginning of the
// object we just read
input->setLastOffset(offset);
return object;
}
QPDFObjectHandle
QPDF::readObjectInternal(PointerHolder<InputSource> input,
int objid, int generation,
bool in_object_stream,
bool in_array, bool in_dictionary)
{
if (in_dictionary && in_array)
{
// Although dictionaries and arrays arbitrarily nest, these
// variables indicate what is at the top of the stack right
// now, so they can, by definition, never both be true.
throw std::logic_error(
"INTERNAL ERROR: readObjectInternal: in_dict && in_array");
}
QPDFObjectHandle object;
off_t offset = input->tell();
std::vector<QPDFObjectHandle> olist;
bool done = false;
while (! done)
{
object = QPDFObjectHandle();
QPDFTokenizer::Token token = readToken(input);
switch (token.getType())
{
case QPDFTokenizer::tt_brace_open:
case QPDFTokenizer::tt_brace_close:
// Don't know what to do with these for now
QTC::TC("qpdf", "QPDF bad brace");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description,
input->getLastOffset(),
"unexpected brace token");
break;
case QPDFTokenizer::tt_array_close:
if (in_array)
{
done = true;
}
else
{
QTC::TC("qpdf", "QPDF bad array close");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description,
input->getLastOffset(),
"unexpected array close token");
}
break;
case QPDFTokenizer::tt_dict_close:
if (in_dictionary)
{
done = true;
}
else
{
QTC::TC("qpdf", "QPDF bad dictionary close");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description,
input->getLastOffset(),
"unexpected dictionary close token");
}
break;
case QPDFTokenizer::tt_array_open:
object = readObjectInternal(
input, objid, generation, in_object_stream, true, false);
break;
case QPDFTokenizer::tt_dict_open:
object = readObjectInternal(
input, objid, generation, in_object_stream, false, true);
break;
case QPDFTokenizer::tt_bool:
object = QPDFObjectHandle::newBool(
(token.getValue() == "true"));
break;
case QPDFTokenizer::tt_null:
object = QPDFObjectHandle::newNull();
break;
case QPDFTokenizer::tt_integer:
object = QPDFObjectHandle::newInteger(
atoi(token.getValue().c_str()));
break;
case QPDFTokenizer::tt_real:
object = QPDFObjectHandle::newReal(token.getValue());
break;
case QPDFTokenizer::tt_name:
object = QPDFObjectHandle::newName(token.getValue());
break;
case QPDFTokenizer::tt_word:
{
std::string const& value = token.getValue();
if ((value == "R") && (in_array || in_dictionary) &&
(olist.size() >= 2) &&
(olist[olist.size() - 1].isInteger()) &&
(olist[olist.size() - 2].isInteger()))
{
// Try to resolve indirect objects
object = QPDFObjectHandle::Factory::newIndirect(
this,
olist[olist.size() - 2].getIntValue(),
olist[olist.size() - 1].getIntValue());
olist.pop_back();
olist.pop_back();
}
else if ((value == "endobj") &&
(! (in_array || in_dictionary)))
{
// 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->last_object_description,
input->getLastOffset(),
"empty object treated as null"));
object = QPDFObjectHandle::newNull();
input->seek(input->getLastOffset(), SEEK_SET);
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description,
input->getLastOffset(),
"unknown token while reading object (" +
value + ")");
}
}
break;
case QPDFTokenizer::tt_string:
{
std::string val = token.getValue();
if (this->encrypted && (! in_object_stream))
{
decryptString(val, objid, generation);
}
object = QPDFObjectHandle::newString(val);
}
break;
default:
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description,
input->getLastOffset(),
"unknown token type while reading object");
break;
}
if (in_dictionary || in_array)
{
if (! done)
{
olist.push_back(object);
}
}
else if (! object.isInitialized())
{
throw std::logic_error(
"INTERNAL ERROR: uninitialized object (token = " +
QUtil::int_to_string(token.getType()) +
", " + token.getValue() + ")");
}
else
{
done = true;
}
}
if (in_array)
{
object = QPDFObjectHandle::newArray(olist);
}
else if (in_dictionary)
{
// Convert list to map. Alternating elements are keys.
std::map<std::string, QPDFObjectHandle> dict;
if (olist.size() % 2)
{
QTC::TC("qpdf", "QPDF dictionary odd number of elements");
throw QPDFExc(
qpdf_e_damaged_pdf, input->getName(),
this->last_object_description, input->getLastOffset(),
"dictionary ending here has an odd number of elements");
}
for (unsigned int i = 0; i < olist.size(); i += 2)
{
QPDFObjectHandle key_obj = olist[i];
QPDFObjectHandle val = olist[i + 1];
if (! key_obj.isName())
{
throw QPDFExc(
qpdf_e_damaged_pdf,
input->getName(), this->last_object_description, offset,
std::string("dictionary key not name (") +
key_obj.unparse() + ")");
}
dict[key_obj.getName()] = val;
}
object = QPDFObjectHandle::newDictionary(dict);
if (! in_object_stream)
{
// check for stream
off_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->last_object_description,
input->tell(),
"stream keyword followed"
" by carriage return only"));
}
}
}
else
{
QTC::TC("qpdf", "QPDF stream without newline");
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->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.
off_t stream_offset = input->tell();
size_t length = 0;
try
{
if (dict.count("/Length") == 0)
{
QTC::TC("qpdf", "QPDF stream without length");
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->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->last_object_description, offset,
"/Length key in stream dictionary is not "
"an integer");
}
length = length_obj.getIntValue();
input->seek(stream_offset + (off_t)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->last_object_description,
input->getLastOffset(),
"expected endstream");
}
}
catch (QPDFExc& e)
{
if (this->attempt_recovery)
{
// may throw an exception
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);
}
}
}
return object;
}
size_t
QPDF::recoverStreamLength(PointerHolder<InputSource> input,
int objid, int generation, off_t stream_offset)
{
PCRE endobj_re("^\\s*endobj\\b");
// Try to reconstruct stream length by looking for
// endstream(\r\n?|\n)endobj
warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description, stream_offset,
"attempting to recover stream length"));
input->seek(0, SEEK_END);
off_t eof = input->tell();
input->seek(stream_offset, SEEK_SET);
std::string last_line;
off_t last_line_offset = 0;
size_t length = 0;
while (input->tell() < eof)
{
std::string line = input->readLine();
// Can't use regexp last_line since it might contain nulls
if (endobj_re.match(line.c_str()) &&
(last_line.length() >= 9) &&
(last_line.substr(last_line.length() - 9, 9) == "endstream"))
{
// Stream probably ends right before "endstream", which
// contains 9 characters.
length = last_line_offset + last_line.length() - 9 - stream_offset;
// Go back to where we would have been if we had just read
// the endstream.
input->seek(input->getLastOffset(), SEEK_SET);
break;
}
last_line = line;
last_line_offset = input->getLastOffset();
}
if (length)
{
int this_obj_offset = 0;
ObjGen this_obj(0, 0);
// Make sure this is inside this object
for (std::map<ObjGen, QPDFXRefEntry>::iterator iter =
this->xref_table.begin();
iter != this->xref_table.end(); ++iter)
{
ObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
if (entry.getType() == 1)
{
int 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.obj == objid) &&
(this_obj.gen == 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)
{
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description, stream_offset,
"unable to recover stream data");
}
QTC::TC("qpdf", "QPDF recovered stream length");
return length;
}
QPDFTokenizer::Token
QPDF::readToken(PointerHolder<InputSource> input)
{
off_t offset = input->tell();
QPDFTokenizer::Token token;
bool unread_char;
char char_to_unread;
while (! this->tokenizer.getToken(token, unread_char, char_to_unread))
{
char ch;
if (input->read(&ch, 1) == 0)
{
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description, offset,
"EOF while reading token");
}
else
{
if (isspace((unsigned char)ch) &&
(input->getLastOffset() == offset))
{
++offset;
}
this->tokenizer.presentCharacter(ch);
}
}
if (unread_char)
{
input->unreadCh(char_to_unread);
}
if (token.getType() == QPDFTokenizer::tt_bad)
{
throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
this->last_object_description, offset,
token.getErrorMessage());
}
input->setLastOffset(offset);
return token;
}
QPDFObjectHandle
QPDF::readObjectAtOffset(bool try_recovery,
off_t offset, std::string const& description,
int exp_objid, int exp_generation,
int& objid, int& generation)
{
setLastObjectDescription(description, exp_objid, exp_generation);
this->file->seek(offset, SEEK_SET);
QPDFTokenizer::Token tobjid = readToken(this->file);
QPDFTokenizer::Token tgen = readToken(this->file);
QPDFTokenizer::Token tobj = readToken(this->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->file->getName(),
this->last_object_description, offset,
"expected n n obj");
}
objid = atoi(tobjid.getValue().c_str());
generation = atoi(tgen.getValue().c_str());
if ((exp_objid >= 0) &&
(! ((objid == exp_objid) && (generation == exp_generation))))
{
QTC::TC("qpdf", "QPDF err wrong objid/generation");
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
this->last_object_description, offset,
std::string("expected ") +
QUtil::int_to_string(exp_objid) + " " +
QUtil::int_to_string(exp_generation) + " obj");
}
}
catch (QPDFExc& e)
{
if ((exp_objid >= 0) && try_recovery && this->attempt_recovery)
{
// Try again after reconstructing xref table
reconstruct_xref(e);
ObjGen og(exp_objid, exp_generation);
if (this->xref_table.count(og) &&
(this->xref_table[og].getType() == 1))
{
off_t new_offset = this->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->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->file, description, objid, generation, false);
if (! (readToken(this->file) ==
QPDFTokenizer::Token(QPDFTokenizer::tt_word, "endobj")))
{
QTC::TC("qpdf", "QPDF err expected endobj");
warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
this->last_object_description, this->file->getLastOffset(),
"expected endobj"));
}
ObjGen og(objid, generation);
if (! this->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.
off_t end_before_space = this->file->tell();
// skip over spaces
while (true)
{
char ch;
if (this->file->read(&ch, 1))
{
if (! isspace((unsigned char)ch))
{
this->file->seek(-1, SEEK_CUR);
break;
}
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
this->last_object_description, offset,
"EOF after endobj");
}
}
off_t end_after_space = this->file->tell();
this->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.
ObjGen og(objid, generation);
if (! this->obj_cache.count(og))
{
if (! this->xref_table.count(og))
{
// PDF spec says unknown objects resolve to the null object.
return new QPDF_Null;
}
QPDFXRefEntry const& entry = this->xref_table[og];
switch (entry.getType())
{
case 1:
{
off_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->file->getName(), "", 0,
"object " +
QUtil::int_to_string(objid) + "/" +
QUtil::int_to_string(generation) +
" has unexpected xref entry type");
}
}
return this->obj_cache[og].object;
}
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->file->getName(),
this->last_object_description,
this->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.
ObjGen stream_og(obj_stream_number, 0);
off_t end_before_space = this->obj_cache[stream_og].end_before_space;
off_t end_after_space = this->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->file->getName(),
this->last_object_description,
this->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->file->getName(),
this->last_object_description,
this->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();
PointerHolder<InputSource> input = new BufferInputSource(
"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->last_object_description, input->getLastOffset(),
"expected integer in object stream header");
}
int num = atoi(tnum.getValue().c_str());
int offset = atoi(toffset.getValue().c_str());
offsets[num] = offset + first;
}
for (std::map<int, int>::iterator iter = offsets.begin();
iter != offsets.end(); ++iter)
{
int obj = (*iter).first;
int offset = (*iter).second;
input->seek(offset, SEEK_SET);
QPDFObjectHandle oh = readObject(input, "", obj, 0, true);
// Store in cache
ObjGen og(obj, 0);
this->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh),
end_before_space, end_after_space);
}
}
QPDFObjectHandle
QPDF::makeIndirectObject(QPDFObjectHandle oh)
{
ObjGen o1(0, 0);
if (! this->obj_cache.empty())
{
o1 = (*(this->obj_cache.rbegin())).first;
}
ObjGen o2 = (*(this->xref_table.rbegin())).first;
QTC::TC("qpdf", "QPDF indirect last obj from xref",
(o2.obj > o1.obj) ? 1 : 0);
int max_objid = std::max(o1.obj, o2.obj);
ObjGen next(max_objid + 1, 0);
this->obj_cache[next] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
return QPDFObjectHandle::Factory::newIndirect(this, next.obj, next.gen);
}
QPDFObjectHandle
QPDF::getObjectByID(int objid, int generation)
{
return QPDFObjectHandle::Factory::newIndirect(this, objid, generation);
}
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
ObjGen og(objid, generation);
this->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
}
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);
ObjGen og1(objid1, generation1);
ObjGen og2(objid2, generation2);
ObjCache t = this->obj_cache[og1];
this->obj_cache[og1] = this->obj_cache[og2];
this->obj_cache[og2] = t;
}
void
QPDF::trimTrailerForWrite()
{
// Note that removing the encryption dictionary does not interfere
// with reading encrypted files. QPDF loads all the information
// it needs from the encryption dictionary at the beginning and
// never looks at it again.
this->trailer.removeKey("/ID");
this->trailer.removeKey("/Encrypt");
this->trailer.removeKey("/Prev");
// Remove all trailer keys that potentially come from a
// cross-reference stream
this->trailer.removeKey("/Index");
this->trailer.removeKey("/W");
this->trailer.removeKey("/Length");
this->trailer.removeKey("/Filter");
this->trailer.removeKey("/DecodeParms");
this->trailer.removeKey("/Type");
this->trailer.removeKey("/XRefStm");
}
std::string
QPDF::getFilename() const
{
return this->file->getName();
}
std::string
QPDF::getPDFVersion() const
{
return this->pdf_version;
}
QPDFObjectHandle
QPDF::getTrailer()
{
return this->trailer;
}
QPDFObjectHandle
QPDF::getRoot()
{
return this->trailer.getKey("/Root");
}
void
QPDF::getObjectStreamData(std::map<int, int>& omap)
{
for (std::map<ObjGen, QPDFXRefEntry>::iterator iter =
this->xref_table.begin();
iter != this->xref_table.end(); ++iter)
{
ObjGen const& og = (*iter).first;
QPDFXRefEntry const& entry = (*iter).second;
if (entry.getType() == 2)
{
omap[og.obj] = entry.getObjStreamNumber();
}
}
}
std::vector<int>
QPDF::getCompressibleObjects()
{
// Return a set of object numbers of objects that are allowed to
// be in object streams. We disregard generation numbers here
// since this is a helper function for QPDFWriter which is going
// to renumber objects anyway. This code will do weird things if
// we have two objects with the same object number and different
// generations, but so do virtually all PDF consumers,
// particularly since this is not a permitted condition.
// We 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
int encryption_dict_id = 0;
QPDFObjectHandle encryption_dict = trailer.getKey("/Encrypt");
if (encryption_dict.isIndirect())
{
encryption_dict_id = encryption_dict.getObjectID();
}
std::set<int> visited;
std::list<QPDFObjectHandle> queue;
queue.push_front(this->trailer);
std::vector<int> result;
while (! queue.empty())
{
QPDFObjectHandle obj = queue.front();
queue.pop_front();
if (obj.isIndirect())
{
int objid = obj.getObjectID();
if (visited.count(objid))
{
QTC::TC("qpdf", "QPDF loop detected traversing objects");
continue;
}
if (objid == encryption_dict_id)
{
QTC::TC("qpdf", "QPDF exclude encryption dictionary");
}
else if (! obj.isStream())
{
result.push_back(objid);
}
visited.insert(objid);
}
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;
}
void
QPDF::pipeStreamData(int objid, int generation,
off_t offset, size_t length,
QPDFObjectHandle stream_dict,
Pipeline* pipeline)
{
std::vector<PointerHolder<Pipeline> > to_delete;
if (this->encrypted)
{
decryptStream(pipeline, objid, generation, stream_dict, to_delete);
}
try
{
this->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->file->read(buf, to_read);
if (len == 0)
{
throw QPDFExc(qpdf_e_damaged_pdf,
this->file->getName(),
this->last_object_description,
this->file->getLastOffset(),
"unexpected EOF reading stream data");
}
length -= len;
pipeline->write((unsigned char*)buf, len);
}
}
catch (QPDFExc& e)
{
warn(e);
}
catch (std::runtime_error& e)
{
QTC::TC("qpdf", "QPDF decoding error warning");
warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
"", this->file->getLastOffset(),
"error decoding stream data for object " +
QUtil::int_to_string(objid) + " " +
QUtil::int_to_string(generation) + ": " + e.what()));
}
pipeline->finish();
}
void
QPDF::decodeStreams()
{
for (std::map<ObjGen, QPDFXRefEntry>::iterator iter =
this->xref_table.begin();
iter != this->xref_table.end(); ++iter)
{
ObjGen const& og = (*iter).first;
QPDFObjectHandle obj = getObjectByID(og.obj, og.gen);
if (obj.isStream())
{
Pl_Discard pl;
obj.pipeStreamData(&pl, true, false, false);
}
}
}
std::vector<QPDFObjectHandle> const&
QPDF::getAllPages()
{
if (this->all_pages.empty())
{
getAllPagesInternal(
this->trailer.getKey("/Root").getKey("/Pages"), this->all_pages);
}
return this->all_pages;
}
void
QPDF::getAllPagesInternal(QPDFObjectHandle cur_pages,
std::vector<QPDFObjectHandle>& result)
{
std::string type = cur_pages.getKey("/Type").getName();
if (type == "/Pages")
{
QPDFObjectHandle kids = cur_pages.getKey("/Kids");
int n = kids.getArrayNItems();
for (int i = 0; i < n; ++i)
{
getAllPagesInternal(kids.getArrayItem(i), result);
}
}
else if (type == "/Page")
{
result.push_back(cur_pages);
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
this->last_object_description,
this->file->getLastOffset(),
": invalid Type in page tree");
}
}
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