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Fix handling of hybrid reference files in QPDF::read_xrefTable

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QPDF::read_xrefTable ignores type 0 entries for objects in a section if an
associates XRefStm has an entry for the same object.

The spec states:

When the conforming reader searches for an object, if an entry is not
found in any given standard cross-reference section, the search shall
proceed to a cross-reference stream specified by the XRefStm entry
before looking in the previous cross-reference section,

If a deleted entry is found in a section, the XRefStm is not searched
according to the standard.
This commit is contained in:
m-holger 2024-08-16 15:58:55 +01:00
parent dc1ae8457d
commit f2228b1f88
1 changed files with 3 additions and 13 deletions
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16
libqpdf/QPDF.cc
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@ -952,8 +952,6 @@ QPDF::read_xrefEntry(qpdf_offset_t& f1, int& f2, char& type)
qpdf_offset_t
QPDF::read_xrefTable(qpdf_offset_t xref_offset)
{
std::vector<QPDFObjGen> deleted_items;
m->file->seek(xref_offset, SEEK_SET);
std::string line;
while (true) {
@ -982,8 +980,7 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
"xref table", "invalid xref entry (obj=" + std::to_string(i) + ")");
}
if (type == 'f') {
// Save deleted items until after we've checked the XRefStm, if any.
deleted_items.emplace_back(toI(i), f2);
insertFreeXrefEntry(QPDFObjGen(toI(i), f2));
} else {
insertXrefEntry(toI(i), 1, f1, f2);
}
@ -1030,23 +1027,16 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
}
}
// Handle any deleted items now that we've read the /XRefStm.
for (auto const& og: deleted_items) {
insertFreeXrefEntry(og);
}
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");
}
QTC::TC("qpdf", "QPDF prev key in trailer dictionary");
xref_offset = cur_trailer.getKey("/Prev").getIntValue();
} else {
xref_offset = 0;
return cur_trailer.getKey("/Prev").getIntValue();
}
return xref_offset;
return 0;
}
// Read a single cross-reference stream.