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Code Issues Releases Wiki Activity

Move QPDF::read_xrefEntry to QPDF::Xref_table

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This commit is contained in:
m-holger 2024-08-10 11:47:02 +01:00
parent 3fbff84594
commit 253d3aee8f
3 changed files with 45 additions and 32 deletions
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4
include/qpdf/QPDF.hh
View File

@ -762,10 +762,6 @@ class QPDF
void setTrailer(QPDFObjectHandle obj);
void read_xref(qpdf_offset_t offset);
bool resolveXRefTable();
bool parse_xrefFirst(std::string const& line, int& obj, int& num, int& bytes);
bool read_xrefEntry(qpdf_offset_t& f1, int& f2, char& type);
bool read_bad_xrefEntry(qpdf_offset_t& f1, int& f2, char& type);
qpdf_offset_t read_xrefTable(qpdf_offset_t offset);
qpdf_offset_t read_xrefStream(qpdf_offset_t offset);
qpdf_offset_t processXRefStream(qpdf_offset_t offset, QPDFObjectHandle& xref_stream);
std::pair<int, std::array<int, 3>>

61
libqpdf/QPDF.cc
View File

@ -723,7 +723,7 @@ QPDF::read_xref(qpdf_offset_t xref_offset)
while (QUtil::is_space(buf[skip])) {
++skip;
}
xref_offset = read_xrefTable(xref_offset + skip);
xref_offset = m->xref_table.read_table(xref_offset + skip);
} else {
xref_offset = read_xrefStream(xref_offset);
}
@ -769,7 +769,7 @@ QPDF::read_xref(qpdf_offset_t xref_offset)
}
bool
QPDF::parse_xrefFirst(std::string const& line, int& obj, int& num, int& bytes)
QPDF::Xref_table::parse_first(std::string const& line, int& obj, int& num, int& bytes)
{
// is_space and is_digit both return false on '\0', so this will not overrun the null-terminated
// buffer.
@ -817,8 +817,10 @@ QPDF::parse_xrefFirst(std::string const& line, int& obj, int& num, int& bytes)
}
bool
QPDF::read_bad_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
QPDF::Xref_table::read_bad_entry(qpdf_offset_t& f1, int& f2, char& type)
{
auto* m = qpdf.m.get();
// Reposition after initial read attempt and reread.
m->file->seek(m->file->getLastOffset(), SEEK_SET);
auto line = m->file->readLine(30);
@ -887,7 +889,7 @@ QPDF::read_bad_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
}
if (invalid) {
warn(damagedPDF("xref table", "accepting invalid xref table entry"));
qpdf.warn(damaged_table("accepting invalid xref table entry"));
}
f1 = QUtil::string_to_ll(f1_str.c_str());
@ -899,8 +901,10 @@ QPDF::read_bad_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
// Optimistically read and parse xref entry. If entry is bad, call read_bad_xrefEntry and return
// result.
bool
QPDF::read_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
QPDF::Xref_table::read_entry(qpdf_offset_t& f1, int& f2, char& type)
{
auto* m = qpdf.m.get();
std::array<char, 21> line;
if (m->file->read(line.data(), 20) != 20) {
// C++20: [[unlikely]]
@ -948,13 +952,15 @@ QPDF::read_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
return true;
}
}
return read_bad_xrefEntry(f1, f2, type);
return read_bad_entry(f1, f2, type);
}
// Read a single cross-reference table section and associated trailer.
qpdf_offset_t
QPDF::read_xrefTable(qpdf_offset_t xref_offset)
QPDF::Xref_table::read_table(qpdf_offset_t xref_offset)
{
auto* m = qpdf.m.get();
m->file->seek(xref_offset, SEEK_SET);
std::string line;
while (true) {
@ -963,33 +969,32 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
int obj = 0;
int num = 0;
int bytes = 0;
if (!parse_xrefFirst(line, obj, num, bytes)) {
if (!parse_first(line, obj, num, bytes)) {
QTC::TC("qpdf", "QPDF invalid xref");
throw damagedPDF("xref table", "xref syntax invalid");
throw damaged_table("xref syntax invalid");
}
m->file->seek(m->file->getLastOffset() + bytes, SEEK_SET);
for (qpdf_offset_t i = obj; i - num < obj; ++i) {
if (i == 0) {
// This is needed by checkLinearization()
m->xref_table.first_item_offset = m->file->tell();
first_item_offset = m->file->tell();
}
// For xref_table, these will always be small enough to be ints
qpdf_offset_t f1 = 0;
int f2 = 0;
char type = '\0';
if (!read_xrefEntry(f1, f2, type)) {
if (!read_entry(f1, f2, type)) {
QTC::TC("qpdf", "QPDF invalid xref entry");
throw damagedPDF(
"xref table", "invalid xref entry (obj=" + std::to_string(i) + ")");
throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")");
}
if (type == 'f') {
m->xref_table.insert_free(QPDFObjGen(toI(i), f2));
insert_free(QPDFObjGen(toI(i), f2));
} else {
m->xref_table.insert(toI(i), 1, f1, f2);
insert(toI(i), 1, f1, f2);
}
}
qpdf_offset_t pos = m->file->tell();
if (readToken(*m->file).isWord("trailer")) {
if (qpdf.readToken(*m->file).isWord("trailer")) {
break;
} else {
m->file->seek(pos, SEEK_SET);
@ -997,35 +1002,35 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
}
// Set offset to previous xref table if any
QPDFObjectHandle cur_trailer = readTrailer();
auto cur_trailer = qpdf.readTrailer();
if (!cur_trailer.isDictionary()) {
QTC::TC("qpdf", "QPDF missing trailer");
throw damagedPDF("", "expected trailer dictionary");
throw qpdf.damagedPDF("", "expected trailer dictionary");
}
if (!m->xref_table.trailer) {
setTrailer(cur_trailer);
if (!trailer) {
trailer = cur_trailer;
if (!m->xref_table.trailer.hasKey("/Size")) {
if (!trailer.hasKey("/Size")) {
QTC::TC("qpdf", "QPDF trailer lacks size");
throw damagedPDF("trailer", "trailer dictionary lacks /Size key");
throw qpdf.damagedPDF("trailer", "trailer dictionary lacks /Size key");
}
if (!m->xref_table.trailer.getKey("/Size").isInteger()) {
if (!trailer.getKey("/Size").isInteger()) {
QTC::TC("qpdf", "QPDF trailer size not integer");
throw damagedPDF("trailer", "/Size key in trailer dictionary is not an integer");
throw qpdf.damagedPDF("trailer", "/Size key in trailer dictionary is not an integer");
}
}
if (cur_trailer.hasKey("/XRefStm")) {
if (m->xref_table.ignore_streams) {
if (ignore_streams) {
QTC::TC("qpdf", "QPDF ignoring XRefStm in trailer");
} else {
if (cur_trailer.getKey("/XRefStm").isInteger()) {
// Read the xref stream but disregard any return value -- we'll use our trailer's
// /Prev key instead of the xref stream's.
(void)read_xrefStream(cur_trailer.getKey("/XRefStm").getIntValue());
(void)qpdf.read_xrefStream(cur_trailer.getKey("/XRefStm").getIntValue());
} else {
throw damagedPDF("xref stream", xref_offset, "invalid /XRefStm");
throw qpdf.damagedPDF("xref stream", xref_offset, "invalid /XRefStm");
}
}
}
@ -1033,7 +1038,7 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
if (cur_trailer.hasKey("/Prev")) {
if (!cur_trailer.getKey("/Prev").isInteger()) {
QTC::TC("qpdf", "QPDF trailer prev not integer");
throw damagedPDF("trailer", "/Prev key in trailer dictionary is not an integer");
throw qpdf.damagedPDF("trailer", "/Prev key in trailer dictionary is not an integer");
}
QTC::TC("qpdf", "QPDF prev key in trailer dictionary");
return cur_trailer.getKey("/Prev").getIntValue();

12
libqpdf/qpdf/QPDF_private.hh
View File

@ -12,6 +12,8 @@ class QPDF::Xref_table: public std::map<QPDFObjGen, QPDFXRefEntry>
{
}
qpdf_offset_t read_table(qpdf_offset_t offset);
void insert_reconstructed(int obj, qpdf_offset_t f1, int f2);
void insert(int obj, int f0, qpdf_offset_t f1, int f2);
void insert_free(QPDFObjGen);
@ -33,12 +35,22 @@ class QPDF::Xref_table: public std::map<QPDFObjGen, QPDFXRefEntry>
qpdf_offset_t first_item_offset{0}; // actual value from file
private:
bool parse_first(std::string const& line, int& obj, int& num, int& bytes);
bool read_entry(qpdf_offset_t& f1, int& f2, char& type);
bool read_bad_entry(qpdf_offset_t& f1, int& f2, char& type);
QPDFExc
damaged_pdf(std::string const& msg)
{
return qpdf.damagedPDF("", 0, msg);
}
QPDFExc
damaged_table(std::string const& msg)
{
return qpdf.damagedPDF("xref table", msg);
}
void
warn_damaged(std::string const& msg)
{