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Code Issues Releases Wiki Activity

Remove Xref_table::deleted_objects

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This commit is contained in:
m-holger 2024-08-15 23:09:29 +01:00
parent c0020cb17d
commit 6b9eb14c76
2 changed files with 31 additions and 30 deletions
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49
libqpdf/QPDF.cc
View File

@ -634,8 +634,6 @@ QPDF::Xref_table::reconstruct(QPDFExc& e)
check_warnings();
}
deleted_objects.clear();
if (!trailer_) {
qpdf_offset_t max_offset{0};
// If there are any xref streams, take the last one to appear.
@ -764,32 +762,15 @@ QPDF::Xref_table::read(qpdf_offset_t xref_offset)
if (!trailer_) {
throw damaged_pdf("unable to find trailer while reading xref");
}
int size = trailer_.getKey("/Size").getIntValueAsInt();
if (size < 3) {
throw damaged_pdf("too few objects - file can't have a page tree");
}
// We are no longer reporting what the highest id in the xref table is. I don't think it adds
// anything. If we want to report more detail, we should report the total number of missing
// entries, including missing entries before the last actual entry.
//
// int size = trailer_.getKey("/Size").getIntValueAsInt();
// int max_obj = 0;
// if (!table.empty()) {
// max_obj = table.rbegin()->first.getObj();
// }
// if (!deleted_objects.empty()) {
// max_obj = std::max(max_obj, *deleted_objects.rbegin());
// }
// if ((size < 1) || (size - 1 != max_obj)) {
// QTC::TC("qpdf", "QPDF xref size mismatch");
// warn_damaged(
// "reported number of objects (" + std::to_string(size) +
// ") is not one plus the highest object number (" + std::to_string(max_obj) + ")");
// }
// We no longer need the deleted_objects table, so go ahead and clear it out to make sure we
// never depend on its being set.
deleted_objects.clear();
// Make sure we keep only the highest generation for any object.
// No longer needed as compliance is guaranteed by vector.
}
QPDF::Xref_table::Subsection
@ -1353,8 +1334,13 @@ QPDF::Xref_table::insert(int obj, int f0, qpdf_offset_t f1, int f2)
}
auto& entry = table[static_cast<size_t>(obj)];
auto old_type = entry.entry.getType();
if (deleted_objects.count(obj)) {
if (!old_type && entry.gen > 0) {
// At the moment we are processing the updates last to first and therefore the gen doesn't
// matter as long as it > 0 to distinguish it from an uninitialized entry. This will need
// to be revisited when we want to support incremental updates or more comprhensive
// checking.
QTC::TC("qpdf", "QPDF xref deleted object");
return;
}
@ -1365,7 +1351,7 @@ QPDF::Xref_table::insert(int obj, int f0, qpdf_offset_t f1, int f2)
return;
}
if (entry.entry.getType() && entry.gen >= new_gen) {
if (old_type && entry.gen >= new_gen) {
QTC::TC("qpdf", "QPDF xref reused object");
return;
}
@ -1391,8 +1377,15 @@ QPDF::Xref_table::insert(int obj, int f0, qpdf_offset_t f1, int f2)
void
QPDF::Xref_table::insert_free(QPDFObjGen og)
{
if (!type(og)) {
deleted_objects.insert(og.getObj());
// At the moment we are processing the updates last to first and therefore the gen doesn't
// matter as long as it > 0 to distinguish it from an uninitialized entry. This will need to be
// revisited when we want to support incremental updates or more comprhensive checking.
if (og.getObj() < 1) {
return;
}
size_t id = static_cast<size_t>(og.getObj());
if (id < table.size() && !type(id)) {
table[id] = {1, {}};
}
}

12
libqpdf/qpdf/QPDF_private.hh
View File

@ -44,6 +44,16 @@ class QPDF::Xref_table
return e.gen == og.getGen() ? e.entry.getType() : 0;
}
// Returns 0 if og is not in table.
int
type(size_t id) const
{
if (id >= table.size()) {
return 0;
}
return table[id].entry.getType();
}
// Returns 0 if og is not in table.
qpdf_offset_t
offset(QPDFObjGen og) const
@ -175,7 +185,6 @@ class QPDF::Xref_table
}
// Methods to insert table entries
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);
@ -207,7 +216,6 @@ class QPDF::Xref_table
bool attempt_recovery_{true};
bool initialized_{false};
bool ignore_streams_{false};
std::set<int> deleted_objects;
bool reconstructed_{false};
// Before the xref table is initialized, max_id_ is an upper bound on the possible object ids
// that could be present in the PDF file. Once the trailer has been read, max_id_ is set to the