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Add private method QPDF::validateStreamLineEnd

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This commit is contained in:
m-holger 2023-07-08 12:17:48 +01:00
parent ef866d68cd
commit aabd3f6f9b
2 changed files with 52 additions and 45 deletions
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1
include/qpdf/QPDF.hh
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@ -1009,6 +1009,7 @@ class QPDF
QPDFObjectHandle readTrailer();
QPDFObjectHandle readObject(std::string const& description, QPDFObjGen og);
void readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset);
void validateStreamLineEnd(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset);
QPDFObjectHandle readObjectInStream(std::shared_ptr<InputSource>, QPDFObjGen og);
size_t recoverStreamLength(
std::shared_ptr<InputSource> input, QPDFObjGen const& og, qpdf_offset_t stream_offset);

96
libqpdf/QPDF.cc
View File

@ -1324,51 +1324,7 @@ QPDF::readObject(std::string const& description, QPDFObjGen og)
void
QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
{
// The PDF specification states that the word "stream" should be followed by either a carriage
// return and a newline or by a newline alone. It specifically disallowed following it by a
// carriage return alone since, in that case, there would be no way to tell whether the NL in a
// CR NL sequence was part of the stream data. However, some readers, including Adobe reader,
// accept a carriage return by itself when followed by a non-newline character, so that's what
// we do here. We have also seen files that have extraneous whitespace between the stream
// keyword and the newline.
while (true) {
char ch;
if (m->file->read(&ch, 1) == 0) {
// A premature EOF here will result in some other problem that will get reported at
// another time.
break;
}
if (ch == '\n') {
// ready to read stream data
QTC::TC("qpdf", "QPDF stream with NL only");
break;
}
if (ch == '\r') {
// Read another character
if (m->file->read(&ch, 1) != 0) {
if (ch == '\n') {
// Ready to read stream data
QTC::TC("qpdf", "QPDF stream with CRNL");
} else {
// Treat the \r by itself as the whitespace after endstream and start reading
// stream data in spite of not having seen a newline.
QTC::TC("qpdf", "QPDF stream with CR only");
m->file->unreadCh(ch);
warn(damagedPDF(
m->file->tell(), "stream keyword followed by carriage return only"));
}
}
break;
}
if (!QUtil::is_space(ch)) {
QTC::TC("qpdf", "QPDF stream without newline");
m->file->unreadCh(ch);
warn(damagedPDF(
m->file->tell(), "stream keyword not followed by proper line terminator"));
break;
}
warn(damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace"));
}
validateStreamLineEnd(object, og, offset);
// Must get offset before accessing any additional objects since resolving a previously
// unresolved indirect object will change file position.
@ -1406,6 +1362,56 @@ QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
object = newIndirect(og, QPDF_Stream::create(this, og, object, stream_offset, length));
}
void
QPDF::validateStreamLineEnd(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
{
// The PDF specification states that the word "stream" should be followed by either a carriage
// return and a newline or by a newline alone. It specifically disallowed following it by a
// carriage return alone since, in that case, there would be no way to tell whether the NL in a
// CR NL sequence was part of the stream data. However, some readers, including Adobe reader,
// accept a carriage return by itself when followed by a non-newline character, so that's what
// we do here. We have also seen files that have extraneous whitespace between the stream
// keyword and the newline.
while (true) {
char ch;
if (m->file->read(&ch, 1) == 0) {
// A premature EOF here will result in some other problem that will get reported at
// another time.
return;
}
if (ch == '\n') {
// ready to read stream data
QTC::TC("qpdf", "QPDF stream with NL only");
return;
}
if (ch == '\r') {
// Read another character
if (m->file->read(&ch, 1) != 0) {
if (ch == '\n') {
// Ready to read stream data
QTC::TC("qpdf", "QPDF stream with CRNL");
} else {
// Treat the \r by itself as the whitespace after endstream and start reading
// stream data in spite of not having seen a newline.
QTC::TC("qpdf", "QPDF stream with CR only");
m->file->unreadCh(ch);
warn(damagedPDF(
m->file->tell(), "stream keyword followed by carriage return only"));
}
}
return;
}
if (!QUtil::is_space(ch)) {
QTC::TC("qpdf", "QPDF stream without newline");
m->file->unreadCh(ch);
warn(damagedPDF(
m->file->tell(), "stream keyword not followed by proper line terminator"));
return;
}
warn(damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace"));
}
}
QPDFObjectHandle
QPDF::readObjectInStream(std::shared_ptr<InputSource> input, QPDFObjGen og)
{