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Code Issues Releases Wiki Activity

Modify QPDF::getObject to not to resolve the object

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This commit is contained in:
m-holger 2022-08-10 13:16:06 +01:00
parent 556c34f0f2
commit c5d0428da2
2 changed files with 32 additions and 21 deletions
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52
libqpdf/QPDF.cc
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@ -26,6 +26,7 @@
#include <qpdf/QPDF_Null.hh>
#include <qpdf/QPDF_Reserved.hh>
#include <qpdf/QPDF_Stream.hh>
#include <qpdf/QPDF_Unresolved.hh>
#include <qpdf/QTC.hh>
#include <qpdf/QUtil.hh>
@ -1397,7 +1398,7 @@ QPDF::fixDanglingReferences(bool force)
std::list<QPDFObjectHandle> queue;
queue.push_back(this->m->trailer);
for (auto const& og: to_process) {
auto obj = getObjectByObjGen(og);
auto obj = getObject(og);
if (obj.isDictionary() || obj.isArray()) {
queue.push_back(obj);
} else if (obj.isStream()) {
@ -1424,11 +1425,10 @@ QPDF::fixDanglingReferences(bool force)
}
for (auto sub: to_check) {
if (sub.isIndirect()) {
if (sub.getOwningQPDF() == this) {
if (!isCached(sub.getObjGen())) {
QTC::TC("qpdf", "QPDF detected dangling ref");
queue.push_back(sub);
}
if ((sub.getOwningQPDF() == this) &&
isUnresolved(sub.getObjGen())) {
QTC::TC("qpdf", "QPDF detected dangling ref");
queue.push_back(sub);
}
} else {
queue.push_back(sub);
@ -1885,7 +1885,7 @@ QPDF::readObjectAtOffset(
"expected endobj");
}
if (!isCached(og)) {
if (isUnresolved(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
@ -1916,8 +1916,8 @@ QPDF::readObjectAtOffset(
}
}
qpdf_offset_t end_after_space = this->m->file->tell();
this->m->obj_cache[og] = ObjCache(
updateCache(
og,
QPDFObjectHandle::ObjAccessor::getObject(oh),
end_before_space,
end_after_space);
@ -1929,6 +1929,11 @@ QPDF::readObjectAtOffset(
std::shared_ptr<QPDFObject>
QPDF::resolve(QPDFObjGen const& og)
{
if (isCached(og) && !isUnresolved(og)) {
// We only need to resolve unresolved objects
return m->obj_cache[og].object;
}
// 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.
@ -1942,11 +1947,13 @@ QPDF::resolve(QPDFObjGen const& og)
"",
this->m->file->getLastOffset(),
("loop detected resolving object " + og.unparse(' ')));
return QPDF_Null::create();
updateCache(og, QPDF_Null::create(), -1, -1);
return m->obj_cache[og].object;
}
ResolveRecorder rr(this, og);
if ((!isCached(og)) && this->m->xref_table.count(og)) {
if (m->xref_table.count(og) != 0) {
QPDFXRefEntry const& entry = this->m->xref_table[og];
try {
switch (entry.getType()) {
@ -1984,12 +1991,11 @@ QPDF::resolve(QPDFObjGen const& og)
": error reading object: " + e.what()));
}
}
if (!isCached(og)) {
if (isUnresolved(og)) {
// PDF spec says unknown objects resolve to the null object.
QTC::TC("qpdf", "QPDF resolve failure to null");
QPDFObjectHandle oh = QPDFObjectHandle::newNull();
this->m->obj_cache[og] =
ObjCache(QPDFObjectHandle::ObjAccessor::getObject(oh), -1, -1);
updateCache(og, QPDF_Null::create(), -1, -1);
}
std::shared_ptr<QPDFObject> result(this->m->obj_cache[og].object);
@ -2084,15 +2090,15 @@ QPDF::resolveObjectsInStream(int obj_stream_number)
// objects appended to the file, so it is necessary to recheck the
// xref table and only cache what would actually be resolved here.
for (auto const& iter: offsets) {
int obj = iter.first;
QPDFObjGen og(obj, 0);
QPDFObjGen og(iter.first, 0);
QPDFXRefEntry const& entry = this->m->xref_table[og];
if ((entry.getType() == 2) &&
(entry.getObjStreamNumber() == obj_stream_number)) {
int offset = iter.second;
input->seek(offset, SEEK_SET);
QPDFObjectHandle oh = readObject(input, "", og, true);
this->m->obj_cache[og] = ObjCache(
updateCache(
og,
QPDFObjectHandle::ObjAccessor::getObject(oh),
end_before_space,
end_after_space);
@ -2176,8 +2182,14 @@ QPDF::reserveStream(QPDFObjGen const& og)
QPDFObjectHandle
QPDF::getObject(QPDFObjGen const& og)
{
auto obj = (og.getObj() != 0) ? resolve(og) : QPDF_Null::create();
return newIndirect(og, obj);
if (!og.isIndirect()) {
return QPDFObjectHandle::newNull();
}
// auto obj = (og.getObj() != 0) ? resolve(og) : QPDF_Null::create();
if (!m->obj_cache.count(og)) {
m->obj_cache[og] = ObjCache(QPDF_Unresolved::create(), -1, -1);
}
return newIndirect(og, m->obj_cache[og].object);
}
QPDFObjectHandle

1
qpdf/qtest/qpdf/issue-51.out
View File

@ -9,7 +9,6 @@ WARNING: issue-51.pdf (object 2 0, offset 26): /Length key in stream dictionary
WARNING: issue-51.pdf (object 2 0, offset 71): attempting to recover stream length
WARNING: issue-51.pdf (object 2 0, offset 71): unable to recover stream data; treating stream as empty
WARNING: issue-51.pdf (object 2 0, offset 977): expected endobj
WARNING: issue-51.pdf (object 2 0, offset 977): EOF after endobj
WARNING: issue-51.pdf (object 3 0): object has offset 0
WARNING: issue-51.pdf (object 4 0): object has offset 0
WARNING: issue-51.pdf (object 5 0): object has offset 0