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qpdf/libqpdf/QPDF_linearization.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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// See doc/linearization.
#include <qpdf/QPDF.hh>
#include <qpdf/QPDFExc.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/Pl_Buffer.hh>
#include <qpdf/Pl_Flate.hh>
#include <qpdf/Pl_Count.hh>
#include <qpdf/BitWriter.hh>
#include <qpdf/BitStream.hh>
#include <iostream>
#include <algorithm>
#include <assert.h>
#include <math.h>
#include <string.h>
template <class T, class int_type>
static void
load_vector_int(BitStream& bit_stream, int nitems, std::vector<T>& vec,
int bits_wanted, int_type T::*field)
{
bool append = vec.empty();
// nitems times, read bits_wanted from the given bit stream,
// storing results in the ith vector entry.
for (int i = 0; i < nitems; ++i)
{
if (append)
{
vec.push_back(T());
}
vec.at(i).*field = bit_stream.getBits(bits_wanted);
}
if (static_cast<int>(vec.size()) != nitems)
{
throw std::logic_error("vector has wrong size in load_vector_int");
}
// The PDF spec says that each hint table starts at a byte
// boundary. Each "row" actually must start on a byte boundary.
bit_stream.skipToNextByte();
}
template <class T>
static void
load_vector_vector(BitStream& bit_stream,
int nitems1, std::vector<T>& vec1, int T::*nitems2,
int bits_wanted, std::vector<int> T::*vec2)
{
// nitems1 times, read nitems2 (from the ith element of vec1) items
// into the vec2 vector field of the ith item of vec1.
for (int i1 = 0; i1 < nitems1; ++i1)
{
for (int i2 = 0; i2 < vec1.at(i1).*nitems2; ++i2)
{
(vec1.at(i1).*vec2).push_back(bit_stream.getBits(bits_wanted));
}
}
bit_stream.skipToNextByte();
}
bool
QPDF::checkLinearization()
{
bool result = false;
try
{
readLinearizationData();
result = checkLinearizationInternal();
}
catch (QPDFExc& e)
{
*this->m->out_stream << e.what() << std::endl;
}
return result;
}
bool
QPDF::isLinearized()
{
// If the first object in the file is a dictionary with a suitable
// /Linearized key and has an /L key that accurately indicates the
// file size, initialize this->m->lindict and return true.
// A linearized PDF spec's first object will be contained within
// the first 1024 bytes of the file and will be a dictionary with
// a valid /Linearized key. This routine looks for that and does
// no additional validation.
// The PDF spec says the linearization dictionary must be
// completely contained within the first 1024 bytes of the file.
// Add a byte for a null terminator.
static int const tbuf_size = 1025;
char* buf = new char[tbuf_size];
this->m->file->seek(0, SEEK_SET);
PointerHolder<char> b(true, buf);
memset(buf, '\0', tbuf_size);
this->m->file->read(buf, tbuf_size - 1);
int lindict_obj = -1;
char* p = buf;
while (lindict_obj == -1)
{
// Find a digit or end of buffer
while (((p - buf) < tbuf_size) && (! QUtil::is_digit(*p)))
{
++p;
}
if (p - buf == tbuf_size)
{
break;
}
// Seek to the digit. Then skip over digits for a potential
// next iteration.
this->m->file->seek(p - buf, SEEK_SET);
while (((p - buf) < tbuf_size) && QUtil::is_digit(*p))
{
++p;
}
QPDFTokenizer::Token t1 = readToken(this->m->file);
QPDFTokenizer::Token t2 = readToken(this->m->file);
QPDFTokenizer::Token t3 = readToken(this->m->file);
QPDFTokenizer::Token t4 = readToken(this->m->file);
if ((t1.getType() == QPDFTokenizer::tt_integer) &&
(t2.getType() == QPDFTokenizer::tt_integer) &&
(t3 == QPDFTokenizer::Token(QPDFTokenizer::tt_word, "obj")) &&
(t4.getType() == QPDFTokenizer::tt_dict_open))
{
lindict_obj =
static_cast<int>(QUtil::string_to_ll(t1.getValue().c_str()));
}
}
if (lindict_obj <= 0)
{
return false;
}
QPDFObjectHandle candidate = QPDFObjectHandle::Factory::newIndirect(
this, lindict_obj, 0);
if (! candidate.isDictionary())
{
return false;
}
QPDFObjectHandle linkey = candidate.getKey("/Linearized");
if (! (linkey.isNumber() &&
(static_cast<int>(floor(linkey.getNumericValue())) == 1)))
{
return false;
}
QPDFObjectHandle L = candidate.getKey("/L");
if (L.isInteger())
{
qpdf_offset_t Li = L.getIntValue();
this->m->file->seek(0, SEEK_END);
if (Li != this->m->file->tell())
{
QTC::TC("qpdf", "QPDF /L mismatch");
return false;
}
else
{
this->m->linp.file_size = Li;
}
}
this->m->lindict = candidate;
return true;
}
void
QPDF::readLinearizationData()
{
// This function throws an exception (which is trapped by
// checkLinearization()) for any errors that prevent loading.
// Hint table parsing code needs at least 32 bits in a long.
assert(sizeof(long) >= 4);
if (! isLinearized())
{
throw std::logic_error("called readLinearizationData for file"
" that is not linearized");
}
// /L is read and stored in linp by isLinearized()
QPDFObjectHandle H = this->m->lindict.getKey("/H");
QPDFObjectHandle O = this->m->lindict.getKey("/O");
QPDFObjectHandle E = this->m->lindict.getKey("/E");
QPDFObjectHandle N = this->m->lindict.getKey("/N");
QPDFObjectHandle T = this->m->lindict.getKey("/T");
QPDFObjectHandle P = this->m->lindict.getKey("/P");
if (! (H.isArray() &&
O.isInteger() &&
E.isInteger() &&
N.isInteger() &&
T.isInteger() &&
(P.isInteger() || P.isNull())))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization dictionary",
this->m->file->getLastOffset(),
"some keys in linearization dictionary are of "
"the wrong type");
}
// Hint table array: offset length [ offset length ]
unsigned int n_H_items = H.getArrayNItems();
if (! ((n_H_items == 2) || (n_H_items == 4)))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization dictionary",
this->m->file->getLastOffset(),
"H has the wrong number of items");
}
std::vector<int> H_items;
for (unsigned int i = 0; i < n_H_items; ++i)
{
QPDFObjectHandle oh(H.getArrayItem(i));
if (oh.isInteger())
{
H_items.push_back(oh.getIntValue());
}
else
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization dictionary",
this->m->file->getLastOffset(),
"some H items are of the wrong type");
}
}
// H: hint table offset/length for primary and overflow hint tables
int H0_offset = H_items.at(0);
int H0_length = H_items.at(1);
int H1_offset = 0;
int H1_length = 0;
if (H_items.size() == 4)
{
// Acrobat doesn't read or write these (as PDF 1.4), so we
// don't have a way to generate a test case.
// QTC::TC("qpdf", "QPDF overflow hint table");
H1_offset = H_items.at(2);
H1_length = H_items.at(3);
}
// P: first page number
int first_page = 0;
if (P.isInteger())
{
QTC::TC("qpdf", "QPDF P present in lindict");
first_page = P.getIntValue();
}
else
{
QTC::TC("qpdf", "QPDF P absent in lindict");
}
// Store linearization parameter data
// Various places in the code use linp.npages, which is
// initialized from N, to pre-allocate memory, so make sure it's
// accurate and bail right now if it's not.
if (N.getIntValue() != static_cast<long long>(getAllPages().size()))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization hint table",
this->m->file->getLastOffset(),
"/N does not match number of pages");
}
// file_size initialized by isLinearized()
this->m->linp.first_page_object = O.getIntValue();
this->m->linp.first_page_end = E.getIntValue();
this->m->linp.npages = N.getIntValue();
this->m->linp.xref_zero_offset = T.getIntValue();
this->m->linp.first_page = first_page;
this->m->linp.H_offset = H0_offset;
this->m->linp.H_length = H0_length;
// Read hint streams
Pl_Buffer pb("hint buffer");
QPDFObjectHandle H0 = readHintStream(pb, H0_offset, H0_length);
if (H1_offset)
{
(void) readHintStream(pb, H1_offset, H1_length);
}
// PDF 1.4 hint tables that we ignore:
// /T thumbnail
// /A thread information
// /E named destination
// /V interactive form
// /I information dictionary
// /C logical structure
// /L page label
// Individual hint table offsets
QPDFObjectHandle HS = H0.getKey("/S"); // shared object
QPDFObjectHandle HO = H0.getKey("/O"); // outline
PointerHolder<Buffer> hbp = pb.getBuffer();
Buffer* hb = hbp.getPointer();
unsigned char const* h_buf = hb->getBuffer();
int h_size = hb->getSize();
readHPageOffset(BitStream(h_buf, h_size));
int HSi = HS.getIntValue();
if ((HSi < 0) || (HSi >= h_size))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization hint table",
this->m->file->getLastOffset(),
"/S (shared object) offset is out of bounds");
}
readHSharedObject(BitStream(h_buf + HSi, h_size - HSi));
if (HO.isInteger())
{
int HOi = HO.getIntValue();
if ((HOi < 0) || (HOi >= h_size))
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization hint table",
this->m->file->getLastOffset(),
"/O (outline) offset is out of bounds");
}
readHGeneric(BitStream(h_buf + HOi, h_size - HOi),
this->m->outline_hints);
}
}
QPDFObjectHandle
QPDF::readHintStream(Pipeline& pl, qpdf_offset_t offset, size_t length)
{
int obj;
int gen;
QPDFObjectHandle H = readObjectAtOffset(
false, offset, "linearization hint stream", -1, 0, obj, gen);
ObjCache& oc = this->m->obj_cache[QPDFObjGen(obj, gen)];
qpdf_offset_t min_end_offset = oc.end_before_space;
qpdf_offset_t max_end_offset = oc.end_after_space;
if (! H.isStream())
{
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization dictionary",
this->m->file->getLastOffset(),
"hint table is not a stream");
}
QPDFObjectHandle Hdict = H.getDict();
// Some versions of Acrobat make /Length indirect and place it
// immediately after the stream, increasing length to cover it,
// even though the specification says all objects in the
// linearization parameter dictionary must be direct. We have to
// get the file position of the end of length in this case.
QPDFObjectHandle length_obj = Hdict.getKey("/Length");
if (length_obj.isIndirect())
{
QTC::TC("qpdf", "QPDF hint table length indirect");
// Force resolution
(void) length_obj.getIntValue();
ObjCache& oc = this->m->obj_cache[length_obj.getObjGen()];
min_end_offset = oc.end_before_space;
max_end_offset = oc.end_after_space;
}
else
{
QTC::TC("qpdf", "QPDF hint table length direct");
}
qpdf_offset_t computed_end = offset + length;
if ((computed_end < min_end_offset) ||
(computed_end > max_end_offset))
{
*this->m->out_stream << "expected = " << computed_end
<< "; actual = " << min_end_offset << ".."
<< max_end_offset << std::endl;
throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
"linearization dictionary",
this->m->file->getLastOffset(),
"hint table length mismatch");
}
H.pipeStreamData(&pl, 0, qpdf_dl_specialized);
return Hdict;
}
void
QPDF::readHPageOffset(BitStream h)
{
// All comments referring to the PDF spec refer to the spec for
// version 1.4.
HPageOffset& t = this->m->page_offset_hints;
t.min_nobjects = h.getBits(32); // 1
t.first_page_offset = h.getBits(32); // 2
t.nbits_delta_nobjects = h.getBits(16); // 3
t.min_page_length = h.getBits(32); // 4
t.nbits_delta_page_length = h.getBits(16); // 5
t.min_content_offset = h.getBits(32); // 6
t.nbits_delta_content_offset = h.getBits(16); // 7
t.min_content_length = h.getBits(32); // 8
t.nbits_delta_content_length = h.getBits(16); // 9
t.nbits_nshared_objects = h.getBits(16); // 10
t.nbits_shared_identifier = h.getBits(16); // 11
t.nbits_shared_numerator = h.getBits(16); // 12
t.shared_denominator = h.getBits(16); // 13
std::vector<HPageOffsetEntry>& entries = t.entries;
entries.clear();
unsigned int nitems = this->m->linp.npages;
load_vector_int(h, nitems, entries,
t.nbits_delta_nobjects,
&HPageOffsetEntry::delta_nobjects);
load_vector_int(h, nitems, entries,
t.nbits_delta_page_length,
&HPageOffsetEntry::delta_page_length);
load_vector_int(h, nitems, entries,
t.nbits_nshared_objects,
&HPageOffsetEntry::nshared_objects);
load_vector_vector(h, nitems, entries,
&HPageOffsetEntry::nshared_objects,
t.nbits_shared_identifier,
&HPageOffsetEntry::shared_identifiers);
load_vector_vector(h, nitems, entries,
&HPageOffsetEntry::nshared_objects,
t.nbits_shared_numerator,
&HPageOffsetEntry::shared_numerators);
load_vector_int(h, nitems, entries,
t.nbits_delta_content_offset,
&HPageOffsetEntry::delta_content_offset);
load_vector_int(h, nitems, entries,
t.nbits_delta_content_length,
&HPageOffsetEntry::delta_content_length);
}
void
QPDF::readHSharedObject(BitStream h)
{
HSharedObject& t = this->m->shared_object_hints;
t.first_shared_obj = h.getBits(32); // 1
t.first_shared_offset = h.getBits(32); // 2
t.nshared_first_page = h.getBits(32); // 3
t.nshared_total = h.getBits(32); // 4
t.nbits_nobjects = h.getBits(16); // 5
t.min_group_length = h.getBits(32); // 6
t.nbits_delta_group_length = h.getBits(16); // 7
QTC::TC("qpdf", "QPDF lin nshared_total > nshared_first_page",
(t.nshared_total > t.nshared_first_page) ? 1 : 0);
std::vector<HSharedObjectEntry>& entries = t.entries;
entries.clear();
int nitems = t.nshared_total;
load_vector_int(h, nitems, entries,
t.nbits_delta_group_length,
&HSharedObjectEntry::delta_group_length);
load_vector_int(h, nitems, entries,
1, &HSharedObjectEntry::signature_present);
for (int i = 0; i < nitems; ++i)
{
if (entries.at(i).signature_present)
{
// Skip 128-bit MD5 hash. These are not supported by
// acrobat, so they should probably never be there. We
// have no test case for this.
for (int j = 0; j < 4; ++j)
{
(void) h.getBits(32);
}
}
}
load_vector_int(h, nitems, entries,
t.nbits_nobjects,
&HSharedObjectEntry::nobjects_minus_one);
}
void
QPDF::readHGeneric(BitStream h, HGeneric& t)
{
t.first_object = h.getBits(32); // 1
t.first_object_offset = h.getBits(32); // 2
t.nobjects = h.getBits(32); // 3
t.group_length = h.getBits(32); // 4
}
bool
QPDF::checkLinearizationInternal()
{
// All comments referring to the PDF spec refer to the spec for
// version 1.4.
std::list<std::string> errors;
std::list<std::string> warnings;
// Check all values in linearization parameter dictionary
LinParameters& p = this->m->linp;
// L: file size in bytes -- checked by isLinearized
// O: object number of first page
std::vector<QPDFObjectHandle> const& pages = getAllPages();
if (p.first_page_object != pages.at(0).getObjectID())
{
QTC::TC("qpdf", "QPDF err /O mismatch");
errors.push_back("first page object (/O) mismatch");
}
// N: number of pages
int npages = pages.size();
if (p.npages != npages)
{
// Not tested in the test suite
errors.push_back("page count (/N) mismatch");
}
for (int i = 0; i < npages; ++i)
{
QPDFObjectHandle const& page = pages.at(i);
QPDFObjGen og(page.getObjGen());
if (this->m->xref_table[og].getType() == 2)
{
errors.push_back("page dictionary for page " +
QUtil::int_to_string(i) + " is compressed");
}
}
// T: offset of whitespace character preceding xref entry for object 0
this->m->file->seek(p.xref_zero_offset, SEEK_SET);
while (1)
{
char ch;
this->m->file->read(&ch, 1);
if (! ((ch == ' ') || (ch == '\r') || (ch == '\n')))
{
this->m->file->seek(-1, SEEK_CUR);
break;
}
}
if (this->m->file->tell() != this->m->first_xref_item_offset)
{
QTC::TC("qpdf", "QPDF err /T mismatch");
errors.push_back("space before first xref item (/T) mismatch "
"(computed = " +
QUtil::int_to_string(this->m->first_xref_item_offset) +
"; file = " +
QUtil::int_to_string(this->m->file->tell()));
}
// P: first page number -- Implementation note 124 says Acrobat
// ignores this value, so we will too.
// Check numbering of compressed objects in each xref section.
// For linearized files, all compressed objects are supposed to be
// at the end of the containing xref section if any object streams
// are in use.
if (this->m->uncompressed_after_compressed)
{
errors.push_back("linearized file contains an uncompressed object"
" after a compressed one in a cross-reference stream");
}
// Further checking requires optimization and order calculation.
// Don't allow optimization to make changes. If it has to, then
// the file is not properly linearized. We use the xref table to
// figure out which objects are compressed and which are
// uncompressed.
{ // local scope
std::map<int, int> object_stream_data;
for (std::map<QPDFObjGen, QPDFXRefEntry>::const_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)
{
object_stream_data[og.getObj()] = entry.getObjStreamNumber();
}
}
optimize(object_stream_data, false);
calculateLinearizationData(object_stream_data);
}
// E: offset of end of first page -- Implementation note 123 says
// Acrobat includes on extra object here by mistake. pdlin fails
// to place thumbnail images in section 9, so when thumbnails are
// present, it also gets the wrong value for /E. It also doesn't
// count outlines here when it should even though it places them
// in part 6. This code fails to put thread information
// dictionaries in part 9, so it actually gets the wrong value for
// E when threads are present. In that case, it would probably
// agree with pdlin. As of this writing, the test suite doesn't
// contain any files with threads.
if (this->m->part6.empty())
{
throw std::logic_error("linearization part 6 unexpectedly empty");
}
qpdf_offset_t min_E = -1;
qpdf_offset_t max_E = -1;
for (std::vector<QPDFObjectHandle>::iterator iter = this->m->part6.begin();
iter != this->m->part6.end(); ++iter)
{
QPDFObjGen og((*iter).getObjGen());
if (this->m->obj_cache.count(og) == 0)
{
// All objects have to have been dereferenced to be classified.
throw std::logic_error("linearization part6 object not in cache");
}
ObjCache const& oc = this->m->obj_cache[og];
min_E = std::max(min_E, oc.end_before_space);
max_E = std::max(max_E, oc.end_after_space);
}
if ((p.first_page_end < min_E) || (p.first_page_end > max_E))
{
QTC::TC("qpdf", "QPDF warn /E mismatch");
warnings.push_back("end of first page section (/E) mismatch: /E = " +
QUtil::int_to_string(p.first_page_end) +
"; computed = " +
QUtil::int_to_string(min_E) + ".." +
QUtil::int_to_string(max_E));
}
// Check hint tables
std::map<int, int> shared_idx_to_obj;
checkHSharedObject(errors, warnings, pages, shared_idx_to_obj);
checkHPageOffset(errors, warnings, pages, shared_idx_to_obj);
checkHOutlines(warnings);
// Report errors
bool result = true;
if (! errors.empty())
{
result = false;
for (std::list<std::string>::iterator iter = errors.begin();
iter != errors.end(); ++iter)
{
*this->m->out_stream << "ERROR: " << (*iter) << std::endl;
}
}
if (! warnings.empty())
{
result = false;
for (std::list<std::string>::iterator iter = warnings.begin();
iter != warnings.end(); ++iter)
{
*this->m->out_stream << "WARNING: " << (*iter) << std::endl;
}
}
return result;
}
qpdf_offset_t
QPDF::maxEnd(ObjUser const& ou)
{
if (this->m->obj_user_to_objects.count(ou) == 0)
{
stopOnError("no entry in object user table for requested object user");
}
std::set<QPDFObjGen> const& ogs = this->m->obj_user_to_objects[ou];
qpdf_offset_t end = 0;
for (std::set<QPDFObjGen>::const_iterator iter = ogs.begin();
iter != ogs.end(); ++iter)
{
QPDFObjGen const& og = *iter;
if (this->m->obj_cache.count(og) == 0)
{
stopOnError("unknown object referenced in object user table");
}
end = std::max(end, this->m->obj_cache[og].end_after_space);
}
return end;
}
qpdf_offset_t
QPDF::getLinearizationOffset(QPDFObjGen const& og)
{
QPDFXRefEntry entry = this->m->xref_table[og];
qpdf_offset_t result = 0;
switch (entry.getType())
{
case 1:
result = entry.getOffset();
break;
case 2:
// For compressed objects, return the offset of the object
// stream that contains them.
result = getLinearizationOffset(
QPDFObjGen(entry.getObjStreamNumber(), 0));
break;
default:
throw std::logic_error(
"getLinearizationOffset called for xref entry not of type 1 or 2");
break;
}
return result;
}
QPDFObjectHandle
QPDF::getUncompressedObject(QPDFObjectHandle& obj,
std::map<int, int> const& object_stream_data)
{
if (obj.isNull() || (object_stream_data.count(obj.getObjectID()) == 0))
{
return obj;
}
else
{
int repl = (*(object_stream_data.find(obj.getObjectID()))).second;
return objGenToIndirect(QPDFObjGen(repl, 0));
}
}
int
QPDF::lengthNextN(int first_object, int n,
std::list<std::string>& errors)
{
int length = 0;
for (int i = 0; i < n; ++i)
{
QPDFObjGen og(first_object + i, 0);
if (this->m->xref_table.count(og) == 0)
{
errors.push_back(
"no xref table entry for " +
QUtil::int_to_string(first_object + i) + " 0");
}
else
{
if (this->m->obj_cache.count(og) == 0)
{
stopOnError("found unknown object while"
" calculating length for linearization data");
}
length += this->m->obj_cache[og].end_after_space -
getLinearizationOffset(og);
}
}
return length;
}
void
QPDF::checkHPageOffset(std::list<std::string>& errors,
std::list<std::string>& warnings,
std::vector<QPDFObjectHandle> const& pages,
std::map<int, int>& shared_idx_to_obj)
{
// Implementation note 126 says Acrobat always sets
// delta_content_offset and delta_content_length in the page
// offset header dictionary to 0. It also states that
// min_content_offset in the per-page information is always 0,
// which is an incorrect value.
// Implementation note 127 explains that Acrobat always sets item
// 8 (min_content_length) to zero, item 9
// (nbits_delta_content_length) to the value of item 5
// (nbits_delta_page_length), and item 7 of each per-page hint
// table (delta_content_length) to item 2 (delta_page_length) of
// that entry. Acrobat ignores these values when reading files.
// Empirically, it also seems that Acrobat sometimes puts items
// under a page's /Resources dictionary in with shared objects
// even when they are private.
unsigned int npages = pages.size();
int table_offset = adjusted_offset(
this->m->page_offset_hints.first_page_offset);
QPDFObjGen first_page_og(pages.at(0).getObjGen());
if (this->m->xref_table.count(first_page_og) == 0)
{
stopOnError("supposed first page object is not known");
}
int offset = getLinearizationOffset(first_page_og);
if (table_offset != offset)
{
warnings.push_back("first page object offset mismatch");
}
for (unsigned int pageno = 0; pageno < npages; ++pageno)
{
QPDFObjGen page_og(pages.at(pageno).getObjGen());
int first_object = page_og.getObj();
if (this->m->xref_table.count(page_og) == 0)
{
stopOnError("unknown object in page offset hint table");
}
offset = getLinearizationOffset(page_og);
HPageOffsetEntry& he = this->m->page_offset_hints.entries.at(pageno);
CHPageOffsetEntry& ce = this->m->c_page_offset_data.entries.at(pageno);
int h_nobjects = he.delta_nobjects +
this->m->page_offset_hints.min_nobjects;
if (h_nobjects != ce.nobjects)
{
// This happens with pdlin when there are thumbnails.
warnings.push_back(
"object count mismatch for page " +
QUtil::int_to_string(pageno) + ": hint table = " +
QUtil::int_to_string(h_nobjects) + "; computed = " +
QUtil::int_to_string(ce.nobjects));
}
// Use value for number of objects in hint table rather than
// computed value if there is a discrepancy.
int length = lengthNextN(first_object, h_nobjects, errors);
int h_length = he.delta_page_length +
this->m->page_offset_hints.min_page_length;
if (length != h_length)
{
// This condition almost certainly indicates a bad hint
// table or a bug in this code.
errors.push_back(
"page length mismatch for page " +
QUtil::int_to_string(pageno) + ": hint table = " +
QUtil::int_to_string(h_length) + "; computed length = " +
QUtil::int_to_string(length) + " (offset = " +
QUtil::int_to_string(offset) + ")");
}
offset += h_length;
// Translate shared object indexes to object numbers.
std::set<int> hint_shared;
std::set<int> computed_shared;
if ((pageno == 0) && (he.nshared_objects > 0))
{
// pdlin and Acrobat both do this even though the spec
// states clearly and unambiguously that they should not.
warnings.push_back("page 0 has shared identifier entries");
}
for (int i = 0; i < he.nshared_objects; ++i)
{
int idx = he.shared_identifiers.at(i);
if (shared_idx_to_obj.count(idx) == 0)
{
throw std::logic_error(
"unable to get object for item in"
" shared objects hint table");
}
hint_shared.insert(shared_idx_to_obj[idx]);
}
for (int i = 0; i < ce.nshared_objects; ++i)
{
int idx = ce.shared_identifiers.at(i);
if (idx >= this->m->c_shared_object_data.nshared_total)
{
throw std::logic_error(
"index out of bounds for shared object hint table");
}
int obj = this->m->c_shared_object_data.entries.at(idx).object;
computed_shared.insert(obj);
}
for (std::set<int>::iterator iter = hint_shared.begin();
iter != hint_shared.end(); ++iter)
{
if (! computed_shared.count(*iter))
{
// pdlin puts thumbnails here even though it shouldn't
warnings.push_back(
"page " + QUtil::int_to_string(pageno) +
": shared object " + QUtil::int_to_string(*iter) +
": in hint table but not computed list");
}
}
for (std::set<int>::iterator iter = computed_shared.begin();
iter != computed_shared.end(); ++iter)
{
if (! hint_shared.count(*iter))
{
// Acrobat does not put some things including at least
// built-in fonts and procsets here, at least in some
// cases.
warnings.push_back(
"page " + QUtil::int_to_string(pageno) +
": shared object " + QUtil::int_to_string(*iter) +
": in computed list but not hint table");
}
}
}
}
void
QPDF::checkHSharedObject(std::list<std::string>& errors,
std::list<std::string>& warnings,
std::vector<QPDFObjectHandle> const& pages,
std::map<int, int>& idx_to_obj)
{
// Implementation note 125 says shared object groups always
// contain only one object. Implementation note 128 says that
// Acrobat always nbits_nobjects to zero. Implementation note 130
// says that Acrobat does not support more than one shared object
// per group. These are all consistent.
// Implementation note 129 states that MD5 signatures are not
// implemented in Acrobat, so signature_present must always be
// zero.
// Implementation note 131 states that first_shared_obj and
// first_shared_offset have meaningless values for single-page
// files.
// Empirically, Acrobat and pdlin generate incorrect values for
// these whenever there are no shared objects not referenced by
// the first page (i.e., nshared_total == nshared_first_page).
HSharedObject& so = this->m->shared_object_hints;
if (so.nshared_total < so.nshared_first_page)
{
errors.push_back("shared object hint table: ntotal < nfirst_page");
}
else
{
// The first nshared_first_page objects are consecutive
// objects starting with the first page object. The rest are
// consecutive starting from the first_shared_obj object.
int cur_object = pages.at(0).getObjectID();
for (int i = 0; i < so.nshared_total; ++i)
{
if (i == so.nshared_first_page)
{
QTC::TC("qpdf", "QPDF lin check shared past first page");
if (this->m->part8.empty())
{
errors.push_back(
"part 8 is empty but nshared_total > "
"nshared_first_page");
}
else
{
int obj = this->m->part8.at(0).getObjectID();
if (obj != so.first_shared_obj)
{
errors.push_back(
"first shared object number mismatch: "
"hint table = " +
QUtil::int_to_string(so.first_shared_obj) +
"; computed = " +
QUtil::int_to_string(obj));
}
}
cur_object = so.first_shared_obj;
QPDFObjGen og(cur_object, 0);
if (this->m->xref_table.count(og) == 0)
{
stopOnError("unknown object in shared object hint table");
}
int offset = getLinearizationOffset(og);
int h_offset = adjusted_offset(so.first_shared_offset);
if (offset != h_offset)
{
errors.push_back(
"first shared object offset mismatch: hint table = " +
QUtil::int_to_string(h_offset) + "; computed = " +
QUtil::int_to_string(offset));
}
}
idx_to_obj[i] = cur_object;
HSharedObjectEntry& se = so.entries.at(i);
int nobjects = se.nobjects_minus_one + 1;
int length = lengthNextN(cur_object, nobjects, errors);
int h_length = so.min_group_length + se.delta_group_length;
if (length != h_length)
{
errors.push_back(
"shared object " + QUtil::int_to_string(i) +
" length mismatch: hint table = " +
QUtil::int_to_string(h_length) + "; computed = " +
QUtil::int_to_string(length));
}
cur_object += nobjects;
}
}
}
void
QPDF::checkHOutlines(std::list<std::string>& warnings)
{
// Empirically, Acrobat generates the correct value for the object
// number but incorrectly stores the next object number's offset
// as the offset, at least when outlines appear in part 6. It
// also generates an incorrect value for length (specifically, the
// length that would cover the correct number of objects from the
// wrong starting place). pdlin appears to generate correct
// values in those cases.
if (this->m->c_outline_data.nobjects == this->m->outline_hints.nobjects)
{
if (this->m->c_outline_data.nobjects == 0)
{
return;
}
if (this->m->c_outline_data.first_object ==
this->m->outline_hints.first_object)
{
// Check length and offset. Acrobat gets these wrong.
QPDFObjectHandle outlines = getRoot().getKey("/Outlines");
if (! outlines.isIndirect())
{
// This case is not exercised in test suite since not
// permitted by the spec, but if this does occur, the
// code below would fail.
warnings.push_back(
"/Outlines key of root dictionary is not indirect");
return;
}
QPDFObjGen og(outlines.getObjGen());
if (this->m->xref_table.count(og) == 0)
{
stopOnError("unknown object in outlines hint table");
}
int offset = getLinearizationOffset(og);
ObjUser ou(ObjUser::ou_root_key, "/Outlines");
int length = maxEnd(ou) - offset;
int table_offset =
adjusted_offset(this->m->outline_hints.first_object_offset);
if (offset != table_offset)
{
warnings.push_back(
"incorrect offset in outlines table: hint table = " +
QUtil::int_to_string(table_offset) +
"; computed = " + QUtil::int_to_string(offset));
}
int table_length = this->m->outline_hints.group_length;
if (length != table_length)
{
warnings.push_back(
"incorrect length in outlines table: hint table = " +
QUtil::int_to_string(table_length) +
"; computed = " + QUtil::int_to_string(length));
}
}
else
{
warnings.push_back("incorrect first object number in outline "
"hints table.");
}
}
else
{
warnings.push_back("incorrect object count in outline hint table");
}
}
void
QPDF::showLinearizationData()
{
try
{
readLinearizationData();
checkLinearizationInternal();
dumpLinearizationDataInternal();
}
catch (QPDFExc& e)
{
*this->m->out_stream << e.what() << std::endl;
}
}
void
QPDF::dumpLinearizationDataInternal()
{
*this->m->out_stream
<< this->m->file->getName() << ": linearization data:" << std::endl
<< std::endl;
*this->m->out_stream
<< "file_size: " << this->m->linp.file_size << std::endl
<< "first_page_object: " << this->m->linp.first_page_object << std::endl
<< "first_page_end: " << this->m->linp.first_page_end << std::endl
<< "npages: " << this->m->linp.npages << std::endl
<< "xref_zero_offset: " << this->m->linp.xref_zero_offset << std::endl
<< "first_page: " << this->m->linp.first_page << std::endl
<< "H_offset: " << this->m->linp.H_offset << std::endl
<< "H_length: " << this->m->linp.H_length << std::endl
<< std::endl;
*this->m->out_stream << "Page Offsets Hint Table" << std::endl
<< std::endl;
dumpHPageOffset();
*this->m->out_stream << std::endl
<< "Shared Objects Hint Table" << std::endl
<< std::endl;
dumpHSharedObject();
if (this->m->outline_hints.nobjects > 0)
{
*this->m->out_stream << std::endl
<< "Outlines Hint Table" << std::endl
<< std::endl;
dumpHGeneric(this->m->outline_hints);
}
}
int
QPDF::adjusted_offset(int offset)
{
// All offsets >= H_offset have to be increased by H_length
// since all hint table location values disregard the hint table
// itself.
if (offset >= this->m->linp.H_offset)
{
return offset + this->m->linp.H_length;
}
return offset;
}
void
QPDF::dumpHPageOffset()
{
HPageOffset& t = this->m->page_offset_hints;
*this->m->out_stream
<< "min_nobjects: " << t.min_nobjects
<< std::endl
<< "first_page_offset: " << adjusted_offset(t.first_page_offset)
<< std::endl
<< "nbits_delta_nobjects: " << t.nbits_delta_nobjects
<< std::endl
<< "min_page_length: " << t.min_page_length
<< std::endl
<< "nbits_delta_page_length: " << t.nbits_delta_page_length
<< std::endl
<< "min_content_offset: " << t.min_content_offset
<< std::endl
<< "nbits_delta_content_offset: " << t.nbits_delta_content_offset
<< std::endl
<< "min_content_length: " << t.min_content_length
<< std::endl
<< "nbits_delta_content_length: " << t.nbits_delta_content_length
<< std::endl
<< "nbits_nshared_objects: " << t.nbits_nshared_objects
<< std::endl
<< "nbits_shared_identifier: " << t.nbits_shared_identifier
<< std::endl
<< "nbits_shared_numerator: " << t.nbits_shared_numerator
<< std::endl
<< "shared_denominator: " << t.shared_denominator
<< std::endl;
for (int i1 = 0; i1 < this->m->linp.npages; ++i1)
{
HPageOffsetEntry& pe = t.entries.at(i1);
*this->m->out_stream
<< "Page " << i1 << ":" << std::endl
<< " nobjects: " << pe.delta_nobjects + t.min_nobjects
<< std::endl
<< " length: " << pe.delta_page_length + t.min_page_length
<< std::endl
// content offset is relative to page, not file
<< " content_offset: "
<< pe.delta_content_offset + t.min_content_offset << std::endl
<< " content_length: "
<< pe.delta_content_length + t.min_content_length << std::endl
<< " nshared_objects: " << pe.nshared_objects << std::endl;
for (int i2 = 0; i2 < pe.nshared_objects; ++i2)
{
*this->m->out_stream << " identifier " << i2 << ": "
<< pe.shared_identifiers.at(i2) << std::endl;
*this->m->out_stream << " numerator " << i2 << ": "
<< pe.shared_numerators.at(i2) << std::endl;
}
}
}
void
QPDF::dumpHSharedObject()
{
HSharedObject& t = this->m->shared_object_hints;
*this->m->out_stream
<< "first_shared_obj: " << t.first_shared_obj
<< std::endl
<< "first_shared_offset: " << adjusted_offset(t.first_shared_offset)
<< std::endl
<< "nshared_first_page: " << t.nshared_first_page
<< std::endl
<< "nshared_total: " << t.nshared_total
<< std::endl
<< "nbits_nobjects: " << t.nbits_nobjects
<< std::endl
<< "min_group_length: " << t.min_group_length
<< std::endl
<< "nbits_delta_group_length: " << t.nbits_delta_group_length
<< std::endl;
for (int i = 0; i < t.nshared_total; ++i)
{
HSharedObjectEntry& se = t.entries.at(i);
*this->m->out_stream
<< "Shared Object " << i << ":" << std::endl
<< " group length: "
<< se.delta_group_length + t.min_group_length << std::endl;
// PDF spec says signature present nobjects_minus_one are
// always 0, so print them only if they have a non-zero value.
if (se.signature_present)
{
*this->m->out_stream << " signature present" << std::endl;
}
if (se.nobjects_minus_one != 0)
{
*this->m->out_stream << " nobjects: "
<< se.nobjects_minus_one + 1 << std::endl;
}
}
}
void
QPDF::dumpHGeneric(HGeneric& t)
{
*this->m->out_stream
<< "first_object: " << t.first_object
<< std::endl
<< "first_object_offset: " << adjusted_offset(t.first_object_offset)
<< std::endl
<< "nobjects: " << t.nobjects
<< std::endl
<< "group_length: " << t.group_length
<< std::endl;
}
QPDFObjectHandle
QPDF::objGenToIndirect(QPDFObjGen const& og)
{
return getObjectByID(og.getObj(), og.getGen());
}
void
QPDF::calculateLinearizationData(std::map<int, int> const& object_stream_data)
{
// This function calculates the ordering of objects, divides them
// into the appropriate parts, and computes some values for the
// linearization parameter dictionary and hint tables. The file
// must be optimized (via calling optimize()) prior to calling
// this function. Note that actual offsets and lengths are not
// computed here, but anything related to object ordering is.
if (this->m->object_to_obj_users.empty())
{
// Note that we can't call optimize here because we don't know
// whether it should be called with or without allow changes.
throw std::logic_error(
"INTERNAL ERROR: QPDF::calculateLinearizationData "
"called before optimize()");
}
// Separate objects into the categories sufficient for us to
// determine which part of the linearized file should contain the
// object. This categorization is useful for other purposes as
// well. Part numbers refer to version 1.4 of the PDF spec.
// Parts 1, 3, 5, 10, and 11 don't contain any objects from the
// original file (except the trailer dictionary in part 11).
// Part 4 is the document catalog (root) and the following root
// keys: /ViewerPreferences, /PageMode, /Threads, /OpenAction,
// /AcroForm, /Encrypt. Note that Thread information dictionaries
// are supposed to appear in part 9, but we are disregarding that
// recommendation for now.
// Part 6 is the first page section. It includes all remaining
// objects referenced by the first page including shared objects
// but not including thumbnails. Additionally, if /PageMode is
// /Outlines, then information from /Outlines also appears here.
// Part 7 contains remaining objects private to pages other than
// the first page.
// Part 8 contains all remaining shared objects except those that
// are shared only within thumbnails.
// Part 9 contains all remaining objects.
// We sort objects into the following categories:
// * open_document: part 4
// * first_page_private: part 6
// * first_page_shared: part 6
// * other_page_private: part 7
// * other_page_shared: part 8
// * thumbnail_private: part 9
// * thumbnail_shared: part 9
// * other: part 9
// * outlines: part 6 or 9
this->m->part4.clear();
this->m->part6.clear();
this->m->part7.clear();
this->m->part8.clear();
this->m->part9.clear();
this->m->c_linp = LinParameters();
this->m->c_page_offset_data = CHPageOffset();
this->m->c_shared_object_data = CHSharedObject();
this->m->c_outline_data = HGeneric();
QPDFObjectHandle root = getRoot();
bool outlines_in_first_page = false;
QPDFObjectHandle pagemode = root.getKey("/PageMode");
QTC::TC("qpdf", "QPDF categorize pagemode present",
pagemode.isName() ? 1 : 0);
if (pagemode.isName())
{
if (pagemode.getName() == "/UseOutlines")
{
if (root.hasKey("/Outlines"))
{
outlines_in_first_page = true;
}
else
{
QTC::TC("qpdf", "QPDF UseOutlines but no Outlines");
}
}
QTC::TC("qpdf", "QPDF categorize pagemode outlines",
outlines_in_first_page ? 1 : 0);
}
std::set<std::string> open_document_keys;
open_document_keys.insert("/ViewerPreferences");
open_document_keys.insert("/PageMode");
open_document_keys.insert("/Threads");
open_document_keys.insert("/OpenAction");
open_document_keys.insert("/AcroForm");
std::set<QPDFObjGen> lc_open_document;
std::set<QPDFObjGen> lc_first_page_private;
std::set<QPDFObjGen> lc_first_page_shared;
std::set<QPDFObjGen> lc_other_page_private;
std::set<QPDFObjGen> lc_other_page_shared;
std::set<QPDFObjGen> lc_thumbnail_private;
std::set<QPDFObjGen> lc_thumbnail_shared;
std::set<QPDFObjGen> lc_other;
std::set<QPDFObjGen> lc_outlines;
std::set<QPDFObjGen> lc_root;
for (std::map<QPDFObjGen, std::set<ObjUser> >::iterator oiter =
this->m->object_to_obj_users.begin();
oiter != this->m->object_to_obj_users.end(); ++oiter)
{
QPDFObjGen const& og = (*oiter).first;
std::set<ObjUser>& ous = (*oiter).second;
bool in_open_document = false;
bool in_first_page = false;
int other_pages = 0;
int thumbs = 0;
int others = 0;
bool in_outlines = false;
bool is_root = false;
for (std::set<ObjUser>::iterator uiter = ous.begin();
uiter != ous.end(); ++uiter)
{
ObjUser const& ou = *uiter;
switch (ou.ou_type)
{
case ObjUser::ou_trailer_key:
if (ou.key == "/Encrypt")
{
in_open_document = true;
}
else
{
++others;
}
break;
case ObjUser::ou_thumb:
++thumbs;
break;
case ObjUser::ou_root_key:
if (open_document_keys.count(ou.key) > 0)
{
in_open_document = true;
}
else if (ou.key == "/Outlines")
{
in_outlines = true;
}
else
{
++others;
}
break;
case ObjUser::ou_page:
if (ou.pageno == 0)
{
in_first_page = true;
}
else
{
++other_pages;
}
break;
case ObjUser::ou_root:
is_root = true;
break;
case ObjUser::ou_bad:
throw std::logic_error(
"INTERNAL ERROR: QPDF::calculateLinearizationData: "
"invalid user type");
break;
}
}
if (is_root)
{
lc_root.insert(og);
}
else if (in_outlines)
{
lc_outlines.insert(og);
}
else if (in_open_document)
{
lc_open_document.insert(og);
}
else if ((in_first_page) &&
(others == 0) && (other_pages == 0) && (thumbs == 0))
{
lc_first_page_private.insert(og);
}
else if (in_first_page)
{
lc_first_page_shared.insert(og);
}
else if ((other_pages == 1) && (others == 0) && (thumbs == 0))
{
lc_other_page_private.insert(og);
}
else if (other_pages > 1)
{
lc_other_page_shared.insert(og);
}
else if ((thumbs == 1) && (others == 0))
{
lc_thumbnail_private.insert(og);
}
else if (thumbs > 1)
{
lc_thumbnail_shared.insert(og);
}
else
{
lc_other.insert(og);
}
}
// Generate ordering for objects in the output file. Sometimes we
// just dump right from a set into a vector. Rather than
// optimizing this by going straight into the vector, we'll leave
// these phases separate for now. That way, this section can be
// concerned only with ordering, and the above section can be
// considered only with categorization. Note that sets of
// QPDFObjGens are sorted by QPDFObjGen. In a linearized file,
// objects appear in sequence with the possible exception of hints
// tables which we won't see here anyway. That means that running
// calculateLinearizationData() on a linearized file should give
// results identical to the original file ordering.
// We seem to traverse the page tree a lot in this code, but we
// can address this for a future code optimization if necessary.
// Premature optimization is the root of all evil.
std::vector<QPDFObjectHandle> pages;
{ // local scope
// Map all page objects to the containing object stream. This
// should be a no-op in a properly linearized file.
std::vector<QPDFObjectHandle> t = getAllPages();
for (std::vector<QPDFObjectHandle>::iterator iter = t.begin();
iter != t.end(); ++iter)
{
pages.push_back(getUncompressedObject(*iter, object_stream_data));
}
}
unsigned int npages = pages.size();
// We will be initializing some values of the computed hint
// tables. Specifically, we can initialize any items that deal
// with object numbers or counts but not any items that deal with
// lengths or offsets. The code that writes linearized files will
// have to fill in these values during the first pass. The
// validation code can compute them relatively easily given the
// rest of the information.
// npages is the size of the existing pages vector, which has been
// created by traversing the pages tree, and as such is a
// reasonable size.
this->m->c_linp.npages = npages;
this->m->c_page_offset_data.entries =
std::vector<CHPageOffsetEntry>(npages);
// Part 4: open document objects. We don't care about the order.
if (lc_root.size() != 1)
{
stopOnError("found other than one root while"
" calculating linearization data");
}
this->m->part4.push_back(objGenToIndirect(*(lc_root.begin())));
for (std::set<QPDFObjGen>::iterator iter = lc_open_document.begin();
iter != lc_open_document.end(); ++iter)
{
this->m->part4.push_back(objGenToIndirect(*iter));
}
// Part 6: first page objects. Note: implementation note 124
// states that Acrobat always treats page 0 as the first page for
// linearization regardless of /OpenAction. pdlin doesn't provide
// any option to set this and also disregards /OpenAction. We
// will do the same.
// First, place the actual first page object itself.
QPDFObjGen first_page_og(pages.at(0).getObjGen());
if (! lc_first_page_private.count(first_page_og))
{
throw std::logic_error(
"INTERNAL ERROR: QPDF::calculateLinearizationData: first page "
"object not in lc_first_page_private");
}
lc_first_page_private.erase(first_page_og);
this->m->c_linp.first_page_object = pages.at(0).getObjectID();
this->m->part6.push_back(pages.at(0));
// The PDF spec "recommends" an order for the rest of the objects,
// but we are going to disregard it except to the extent that it
// groups private and shared objects contiguously for the sake of
// hint tables.
for (std::set<QPDFObjGen>::iterator iter = lc_first_page_private.begin();
iter != lc_first_page_private.end(); ++iter)
{
this->m->part6.push_back(objGenToIndirect(*iter));
}
for (std::set<QPDFObjGen>::iterator iter = lc_first_page_shared.begin();
iter != lc_first_page_shared.end(); ++iter)
{
this->m->part6.push_back(objGenToIndirect(*iter));
}
// Place the outline dictionary if it goes in the first page section.
if (outlines_in_first_page)
{
pushOutlinesToPart(this->m->part6, lc_outlines, object_stream_data);
}
// Fill in page offset hint table information for the first page.
// The PDF spec says that nshared_objects should be zero for the
// first page. pdlin does not appear to obey this, but it fills
// in garbage values for all the shared object identifiers on the
// first page.
this->m->c_page_offset_data.entries.at(0).nobjects = this->m->part6.size();
// Part 7: other pages' private objects
// For each page in order:
for (unsigned int i = 1; i < npages; ++i)
{
// Place this page's page object
QPDFObjGen page_og(pages.at(i).getObjGen());
if (! lc_other_page_private.count(page_og))
{
throw std::logic_error(
"INTERNAL ERROR: "
"QPDF::calculateLinearizationData: page object for page " +
QUtil::int_to_string(i) + " not in lc_other_page_private");
}
lc_other_page_private.erase(page_og);
this->m->part7.push_back(pages.at(i));
// Place all non-shared objects referenced by this page,
// updating the page object count for the hint table.
this->m->c_page_offset_data.entries.at(i).nobjects = 1;
ObjUser ou(ObjUser::ou_page, i);
if (this->m->obj_user_to_objects.count(ou) == 0)
{
stopOnError("found unreferenced page while"
" calculating linearization data");
}
std::set<QPDFObjGen> ogs = this->m->obj_user_to_objects[ou];
for (std::set<QPDFObjGen>::iterator iter = ogs.begin();
iter != ogs.end(); ++iter)
{
QPDFObjGen const& og = (*iter);
if (lc_other_page_private.count(og))
{
lc_other_page_private.erase(og);
this->m->part7.push_back(objGenToIndirect(og));
++this->m->c_page_offset_data.entries.at(i).nobjects;
}
}
}
// That should have covered all part7 objects.
if (! lc_other_page_private.empty())
{
throw std::logic_error(
"INTERNAL ERROR:"
" QPDF::calculateLinearizationData: lc_other_page_private is "
"not empty after generation of part7");
}
// Part 8: other pages' shared objects
// Order is unimportant.
for (std::set<QPDFObjGen>::iterator iter = lc_other_page_shared.begin();
iter != lc_other_page_shared.end(); ++iter)
{
this->m->part8.push_back(objGenToIndirect(*iter));
}
// Part 9: other objects
// The PDF specification makes recommendations on ordering here.
// We follow them only to a limited extent. Specifically, we put
// the pages tree first, then private thumbnail objects in page
// order, then shared thumbnail objects, and then outlines (unless
// in part 6). After that, we throw all remaining objects in
// arbitrary order.
// Place the pages tree.
std::set<QPDFObjGen> pages_ogs =
this->m->obj_user_to_objects[ObjUser(ObjUser::ou_root_key, "/Pages")];
if (pages_ogs.empty())
{
stopOnError("found empty pages tree while"
" calculating linearization data");
}
for (std::set<QPDFObjGen>::iterator iter = pages_ogs.begin();
iter != pages_ogs.end(); ++iter)
{
QPDFObjGen const& og = *iter;
if (lc_other.count(og))
{
lc_other.erase(og);
this->m->part9.push_back(objGenToIndirect(og));
}
}
// Place private thumbnail images in page order. Slightly more
// information would be required if we were going to bother with
// thumbnail hint tables.
for (unsigned int i = 0; i < npages; ++i)
{
QPDFObjectHandle thumb = pages.at(i).getKey("/Thumb");
thumb = getUncompressedObject(thumb, object_stream_data);
if (! thumb.isNull())
{
// Output the thumbnail itself
QPDFObjGen thumb_og(thumb.getObjGen());
if (lc_thumbnail_private.count(thumb_og))
{
lc_thumbnail_private.erase(thumb_og);
this->m->part9.push_back(thumb);
}
else
{
// No internal error this time...there's nothing to
// stop this object from having been referred to
// somewhere else outside of a page's /Thumb, and if
// it had been, there's nothing to prevent it from
// having been in some set other than
// lc_thumbnail_private.
}
std::set<QPDFObjGen>& ogs =
this->m->obj_user_to_objects[ObjUser(ObjUser::ou_thumb, i)];
for (std::set<QPDFObjGen>::iterator iter = ogs.begin();
iter != ogs.end(); ++iter)
{
QPDFObjGen const& og = *iter;
if (lc_thumbnail_private.count(og))
{
lc_thumbnail_private.erase(og);
this->m->part9.push_back(objGenToIndirect(og));
}
}
}
}
if (! lc_thumbnail_private.empty())
{
throw std::logic_error(
"INTERNAL ERROR: "
"QPDF::calculateLinearizationData: lc_thumbnail_private "
"not empty after placing thumbnails");
}
// Place shared thumbnail objects
for (std::set<QPDFObjGen>::iterator iter = lc_thumbnail_shared.begin();
iter != lc_thumbnail_shared.end(); ++iter)
{
this->m->part9.push_back(objGenToIndirect(*iter));
}
// Place outlines unless in first page
if (! outlines_in_first_page)
{
pushOutlinesToPart(this->m->part9, lc_outlines, object_stream_data);
}
// Place all remaining objects
for (std::set<QPDFObjGen>::iterator iter = lc_other.begin();
iter != lc_other.end(); ++iter)
{
this->m->part9.push_back(objGenToIndirect(*iter));
}
// Make sure we got everything exactly once.
unsigned int num_placed =
this->m->part4.size() + this->m->part6.size() + this->m->part7.size() +
this->m->part8.size() + this->m->part9.size();
unsigned int num_wanted = this->m->object_to_obj_users.size();
if (num_placed != num_wanted)
{
throw std::logic_error(
"INTERNAL ERROR: QPDF::calculateLinearizationData: wrong "
"number of objects placed (num_placed = " +
QUtil::int_to_string(num_placed) +
"; number of objects: " +
QUtil::int_to_string(num_wanted));
}
// Calculate shared object hint table information including
// references to shared objects from page offset hint data.
// The shared object hint table consists of all part 6 (whether
// shared or not) in order followed by all part 8 objects in
// order. Add the objects to shared object data keeping a map of
// object number to index. Then populate the shared object
// information for the pages.
// Note that two objects never have the same object number, so we
// can map from object number only without regards to generation.
std::map<int, int> obj_to_index;
this->m->c_shared_object_data.nshared_first_page = this->m->part6.size();
this->m->c_shared_object_data.nshared_total =
this->m->c_shared_object_data.nshared_first_page +
this->m->part8.size();
std::vector<CHSharedObjectEntry>& shared =
this->m->c_shared_object_data.entries;
for (std::vector<QPDFObjectHandle>::iterator iter = this->m->part6.begin();
iter != this->m->part6.end(); ++iter)
{
QPDFObjectHandle& oh = *iter;
int obj = oh.getObjectID();
obj_to_index[obj] = shared.size();
shared.push_back(CHSharedObjectEntry(obj));
}
QTC::TC("qpdf", "QPDF lin part 8 empty", this->m->part8.empty() ? 1 : 0);
if (! this->m->part8.empty())
{
this->m->c_shared_object_data.first_shared_obj =
this->m->part8.at(0).getObjectID();
for (std::vector<QPDFObjectHandle>::iterator iter =
this->m->part8.begin();
iter != this->m->part8.end(); ++iter)
{
QPDFObjectHandle& oh = *iter;
int obj = oh.getObjectID();
obj_to_index[obj] = shared.size();
shared.push_back(CHSharedObjectEntry(obj));
}
}
if (static_cast<size_t>(this->m->c_shared_object_data.nshared_total) !=
this->m->c_shared_object_data.entries.size())
{
throw std::logic_error(
"shared object hint table has wrong number of entries");
}
// Now compute the list of shared objects for each page after the
// first page.
for (unsigned int i = 1; i < npages; ++i)
{
CHPageOffsetEntry& pe = this->m->c_page_offset_data.entries.at(i);
ObjUser ou(ObjUser::ou_page, i);
if (this->m->obj_user_to_objects.count(ou) == 0)
{
stopOnError("found unreferenced page while"
" calculating linearization data");
}
std::set<QPDFObjGen> const& ogs = this->m->obj_user_to_objects[ou];
for (std::set<QPDFObjGen>::const_iterator iter = ogs.begin();
iter != ogs.end(); ++iter)
{
QPDFObjGen const& og = *iter;
if ((this->m->object_to_obj_users[og].size() > 1) &&
(obj_to_index.count(og.getObj()) > 0))
{
int idx = obj_to_index[og.getObj()];
++pe.nshared_objects;
pe.shared_identifiers.push_back(idx);
}
}
}
}
void
QPDF::pushOutlinesToPart(
std::vector<QPDFObjectHandle>& part,
std::set<QPDFObjGen>& lc_outlines,
std::map<int, int> const& object_stream_data)
{
QPDFObjectHandle root = getRoot();
QPDFObjectHandle outlines = root.getKey("/Outlines");
if (outlines.isNull())
{
return;
}
outlines = getUncompressedObject(outlines, object_stream_data);
QPDFObjGen outlines_og(outlines.getObjGen());
QTC::TC("qpdf", "QPDF lin outlines in part",
((&part == (&this->m->part6)) ? 0
: (&part == (&this->m->part9)) ? 1
: 9999)); // can't happen
this->m->c_outline_data.first_object = outlines_og.getObj();
this->m->c_outline_data.nobjects = 1;
lc_outlines.erase(outlines_og);
part.push_back(outlines);
for (std::set<QPDFObjGen>::iterator iter = lc_outlines.begin();
iter != lc_outlines.end(); ++iter)
{
part.push_back(objGenToIndirect(*iter));
++this->m->c_outline_data.nobjects;
}
}
void
QPDF::getLinearizedParts(
std::map<int, int> const& object_stream_data,
std::vector<QPDFObjectHandle>& part4,
std::vector<QPDFObjectHandle>& part6,
std::vector<QPDFObjectHandle>& part7,
std::vector<QPDFObjectHandle>& part8,
std::vector<QPDFObjectHandle>& part9)
{
calculateLinearizationData(object_stream_data);
part4 = this->m->part4;
part6 = this->m->part6;
part7 = this->m->part7;
part8 = this->m->part8;
part9 = this->m->part9;
}
static inline int nbits(int val)
{
return (val == 0 ? 0 : (1 + nbits(val >> 1)));
}
int
QPDF::outputLengthNextN(
int in_object, int n,
std::map<int, qpdf_offset_t> const& lengths,
std::map<int, int> const& obj_renumber)
{
// Figure out the length of a series of n consecutive objects in
// the output file starting with whatever object in_object from
// the input file mapped to.
if (obj_renumber.count(in_object) == 0)
{
stopOnError("found object that is not renumbered while"
" writing linearization data");
}
int first = (*(obj_renumber.find(in_object))).second;
int length = 0;
for (int i = 0; i < n; ++i)
{
if (lengths.count(first + i) == 0)
{
stopOnError("found item with unknown length"
" while writing linearization data");
}
length += (*(lengths.find(first + i))).second;
}
return length;
}
void
QPDF::calculateHPageOffset(
std::map<int, QPDFXRefEntry> const& xref,
std::map<int, qpdf_offset_t> const& lengths,
std::map<int, int> const& obj_renumber)
{
// Page Offset Hint Table
// We are purposely leaving some values set to their initial zero
// values.
std::vector<QPDFObjectHandle> const& pages = getAllPages();
unsigned int npages = pages.size();
CHPageOffset& cph = this->m->c_page_offset_data;
std::vector<CHPageOffsetEntry>& cphe = cph.entries;
// Calculate minimum and maximum values for number of objects per
// page and page length.
int min_nobjects = cphe.at(0).nobjects;
int max_nobjects = min_nobjects;
int min_length = outputLengthNextN(
pages.at(0).getObjectID(), min_nobjects, lengths, obj_renumber);
int max_length = min_length;
int max_shared = cphe.at(0).nshared_objects;
HPageOffset& ph = this->m->page_offset_hints;
std::vector<HPageOffsetEntry>& phe = ph.entries;
// npages is the size of the existing pages array.
phe = std::vector<HPageOffsetEntry>(npages);
for (unsigned int i = 0; i < npages; ++i)
{
// Calculate values for each page, assigning full values to
// the delta items. They will be adjusted later.
// Repeat calculations for page 0 so we can assign to phe[i]
// without duplicating those assignments.
int nobjects = cphe.at(i).nobjects;
int length = outputLengthNextN(
pages.at(i).getObjectID(), nobjects, lengths, obj_renumber);
int nshared = cphe.at(i).nshared_objects;
min_nobjects = std::min(min_nobjects, nobjects);
max_nobjects = std::max(max_nobjects, nobjects);
min_length = std::min(min_length, length);
max_length = std::max(max_length, length);
max_shared = std::max(max_shared, nshared);
phe.at(i).delta_nobjects = nobjects;
phe.at(i).delta_page_length = length;
phe.at(i).nshared_objects = nshared;
}
ph.min_nobjects = min_nobjects;
int in_page0_id = pages.at(0).getObjectID();
int out_page0_id = (*(obj_renumber.find(in_page0_id))).second;
ph.first_page_offset = (*(xref.find(out_page0_id))).second.getOffset();
ph.nbits_delta_nobjects = nbits(max_nobjects - min_nobjects);
ph.min_page_length = min_length;
ph.nbits_delta_page_length = nbits(max_length - min_length);
ph.nbits_nshared_objects = nbits(max_shared);
ph.nbits_shared_identifier =
nbits(this->m->c_shared_object_data.nshared_total);
ph.shared_denominator = 4; // doesn't matter
// It isn't clear how to compute content offset and content
// length. Since we are not interleaving page objects with the
// content stream, we'll use the same values for content length as
// page length. We will use 0 as content offset because this is
// what Adobe does (implementation note 127) and pdlin as well.
ph.nbits_delta_content_length = ph.nbits_delta_page_length;
ph.min_content_length = ph.min_page_length;
for (unsigned int i = 0; i < npages; ++i)
{
// Adjust delta entries
if ((phe.at(i).delta_nobjects < min_nobjects) ||
(phe.at(i).delta_page_length < min_length))
{
stopOnError("found too small delta nobjects or delta page length"
" while writing linearization data");
}
phe.at(i).delta_nobjects -= min_nobjects;
phe.at(i).delta_page_length -= min_length;
phe.at(i).delta_content_length = phe.at(i).delta_page_length;
for (int j = 0; j < cphe.at(i).nshared_objects; ++j)
{
phe.at(i).shared_identifiers.push_back(
cphe.at(i).shared_identifiers.at(j));
phe.at(i).shared_numerators.push_back(0);
}
}
}
void
QPDF::calculateHSharedObject(
std::map<int, QPDFXRefEntry> const& xref,
std::map<int, qpdf_offset_t> const& lengths,
std::map<int, int> const& obj_renumber)
{
CHSharedObject& cso = this->m->c_shared_object_data;
std::vector<CHSharedObjectEntry>& csoe = cso.entries;
HSharedObject& so = this->m->shared_object_hints;
std::vector<HSharedObjectEntry>& soe = so.entries;
soe.clear();
int min_length = outputLengthNextN(
csoe.at(0).object, 1, lengths, obj_renumber);
int max_length = min_length;
for (int i = 0; i < cso.nshared_total; ++i)
{
// Assign absolute numbers to deltas; adjust later
int length = outputLengthNextN(
csoe.at(i).object, 1, lengths, obj_renumber);
min_length = std::min(min_length, length);
max_length = std::max(max_length, length);
soe.push_back(HSharedObjectEntry());
soe.at(i).delta_group_length = length;
}
if (soe.size() != static_cast<size_t>(cso.nshared_total))
{
throw std::logic_error("soe has wrong size after initialization");
}
so.nshared_total = cso.nshared_total;
so.nshared_first_page = cso.nshared_first_page;
if (so.nshared_total > so.nshared_first_page)
{
so.first_shared_obj =
(*(obj_renumber.find(cso.first_shared_obj))).second;
so.first_shared_offset =
(*(xref.find(so.first_shared_obj))).second.getOffset();
}
so.min_group_length = min_length;
so.nbits_delta_group_length = nbits(max_length - min_length);
for (int i = 0; i < cso.nshared_total; ++i)
{
// Adjust deltas
if (soe.at(i).delta_group_length < min_length)
{
stopOnError("found too small group length while"
" writing linearization data");
}
soe.at(i).delta_group_length -= min_length;
}
}
void
QPDF::calculateHOutline(
std::map<int, QPDFXRefEntry> const& xref,
std::map<int, qpdf_offset_t> const& lengths,
std::map<int, int> const& obj_renumber)
{
HGeneric& cho = this->m->c_outline_data;
if (cho.nobjects == 0)
{
return;
}
HGeneric& ho = this->m->outline_hints;
ho.first_object =
(*(obj_renumber.find(cho.first_object))).second;
ho.first_object_offset =
(*(xref.find(ho.first_object))).second.getOffset();
ho.nobjects = cho.nobjects;
ho.group_length = outputLengthNextN(
cho.first_object, ho.nobjects, lengths, obj_renumber);
}
template <class T, class int_type>
static void
write_vector_int(BitWriter& w, int nitems, std::vector<T>& vec,
int bits, int_type T::*field)
{
// nitems times, write bits bits from the given field of the ith
// vector to the given bit writer.
for (int i = 0; i < nitems; ++i)
{
w.writeBits(vec.at(i).*field, bits);
}
// The PDF spec says that each hint table starts at a byte
// boundary. Each "row" actually must start on a byte boundary.
w.flush();
}
template <class T>
static void
write_vector_vector(BitWriter& w,
int nitems1, std::vector<T>& vec1, int T::*nitems2,
int bits, std::vector<int> T::*vec2)
{
// nitems1 times, write nitems2 (from the ith element of vec1) items
// from the vec2 vector field of the ith item of vec1.
for (int i1 = 0; i1 < nitems1; ++i1)
{
for (int i2 = 0; i2 < vec1.at(i1).*nitems2; ++i2)
{
w.writeBits((vec1.at(i1).*vec2).at(i2), bits);
}
}
w.flush();
}
void
QPDF::writeHPageOffset(BitWriter& w)
{
HPageOffset& t = this->m->page_offset_hints;
w.writeBits(t.min_nobjects, 32); // 1
w.writeBits(t.first_page_offset, 32); // 2
w.writeBits(t.nbits_delta_nobjects, 16); // 3
w.writeBits(t.min_page_length, 32); // 4
w.writeBits(t.nbits_delta_page_length, 16); // 5
w.writeBits(t.min_content_offset, 32); // 6
w.writeBits(t.nbits_delta_content_offset, 16); // 7
w.writeBits(t.min_content_length, 32); // 8
w.writeBits(t.nbits_delta_content_length, 16); // 9
w.writeBits(t.nbits_nshared_objects, 16); // 10
w.writeBits(t.nbits_shared_identifier, 16); // 11
w.writeBits(t.nbits_shared_numerator, 16); // 12
w.writeBits(t.shared_denominator, 16); // 13
unsigned int nitems = getAllPages().size();
std::vector<HPageOffsetEntry>& entries = t.entries;
write_vector_int(w, nitems, entries,
t.nbits_delta_nobjects,
&HPageOffsetEntry::delta_nobjects);
write_vector_int(w, nitems, entries,
t.nbits_delta_page_length,
&HPageOffsetEntry::delta_page_length);
write_vector_int(w, nitems, entries,
t.nbits_nshared_objects,
&HPageOffsetEntry::nshared_objects);
write_vector_vector(w, nitems, entries,
&HPageOffsetEntry::nshared_objects,
t.nbits_shared_identifier,
&HPageOffsetEntry::shared_identifiers);
write_vector_vector(w, nitems, entries,
&HPageOffsetEntry::nshared_objects,
t.nbits_shared_numerator,
&HPageOffsetEntry::shared_numerators);
write_vector_int(w, nitems, entries,
t.nbits_delta_content_offset,
&HPageOffsetEntry::delta_content_offset);
write_vector_int(w, nitems, entries,
t.nbits_delta_content_length,
&HPageOffsetEntry::delta_content_length);
}
void
QPDF::writeHSharedObject(BitWriter& w)
{
HSharedObject& t = this->m->shared_object_hints;
w.writeBits(t.first_shared_obj, 32); // 1
w.writeBits(t.first_shared_offset, 32); // 2
w.writeBits(t.nshared_first_page, 32); // 3
w.writeBits(t.nshared_total, 32); // 4
w.writeBits(t.nbits_nobjects, 16); // 5
w.writeBits(t.min_group_length, 32); // 6
w.writeBits(t.nbits_delta_group_length, 16); // 7
QTC::TC("qpdf", "QPDF lin write nshared_total > nshared_first_page",
(t.nshared_total > t.nshared_first_page) ? 1 : 0);
int nitems = t.nshared_total;
std::vector<HSharedObjectEntry>& entries = t.entries;
write_vector_int(w, nitems, entries,
t.nbits_delta_group_length,
&HSharedObjectEntry::delta_group_length);
write_vector_int(w, nitems, entries,
1, &HSharedObjectEntry::signature_present);
for (int i = 0; i < nitems; ++i)
{
// If signature were present, we'd have to write a 128-bit hash.
if (entries.at(i).signature_present != 0)
{
stopOnError("found unexpected signature present"
" while writing linearization data");
}
}
write_vector_int(w, nitems, entries,
t.nbits_nobjects,
&HSharedObjectEntry::nobjects_minus_one);
}
void
QPDF::writeHGeneric(BitWriter& w, HGeneric& t)
{
w.writeBits(t.first_object, 32); // 1
w.writeBits(t.first_object_offset, 32); // 2
w.writeBits(t.nobjects, 32); // 3
w.writeBits(t.group_length, 32); // 4
}
void
QPDF::generateHintStream(std::map<int, QPDFXRefEntry> const& xref,
std::map<int, qpdf_offset_t> const& lengths,
std::map<int, int> const& obj_renumber,
PointerHolder<Buffer>& hint_buffer,
int& S, int& O)
{
// Populate actual hint table values
calculateHPageOffset(xref, lengths, obj_renumber);
calculateHSharedObject(xref, lengths, obj_renumber);
calculateHOutline(xref, lengths, obj_renumber);
// Write the hint stream itself into a compressed memory buffer.
// Write through a counter so we can get offsets.
Pl_Buffer hint_stream("hint stream");
Pl_Flate f("compress hint stream", &hint_stream, Pl_Flate::a_deflate);
Pl_Count c("count", &f);
BitWriter w(&c);
writeHPageOffset(w);
S = c.getCount();
writeHSharedObject(w);
O = 0;
if (this->m->outline_hints.nobjects > 0)
{
O = c.getCount();
writeHGeneric(w, this->m->outline_hints);
}
c.finish();
hint_buffer = hint_stream.getBuffer();
}
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