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Code Issues Releases Wiki Activity

Make QPDF::updateObjectMaps iterative

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This commit is contained in:
Jay Berkenbilt 2024-06-06 12:51:59 -04:00
parent 72e3a9688d
commit d17f11e721
2 changed files with 75 additions and 69 deletions
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18
include/qpdf/QPDF.hh
View File

@ -1343,6 +1343,18 @@ class QPDF
std::string key; // if ou_trailer_key or ou_root_key
};
struct UpdateObjectMapsFrame
{
UpdateObjectMapsFrame(
ObjUser const& ou,
QPDFObjectHandle oh,
bool top);
ObjUser const& ou;
QPDFObjectHandle oh;
bool top;
};
class PatternFinder: public InputSource::Finder
{
public:
@ -1426,12 +1438,6 @@ class QPDF
ObjUser const& ou,
QPDFObjectHandle oh,
std::function<int(QPDFObjectHandle&)> skip_stream_parameters);
void updateObjectMapsInternal(
ObjUser const& ou,
QPDFObjectHandle oh,
std::function<int(QPDFObjectHandle&)> skip_stream_parameters,
QPDFObjGen::set& visited,
bool top);
void filterCompressedObjects(std::map<int, int> const& object_stream_data);
void filterCompressedObjects(QPDFWriter::ObjTable const& object_stream_data);

126
libqpdf/QPDF_optimization.cc
View File

@ -54,6 +54,14 @@ QPDF::ObjUser::operator<(ObjUser const& rhs) const
return false;
}
QPDF::UpdateObjectMapsFrame::UpdateObjectMapsFrame(
QPDF::ObjUser const& ou, QPDFObjectHandle oh, bool top) :
ou(ou),
oh(oh),
top(top)
{
}
void
QPDF::optimize(
std::map<int, int> const& object_stream_data,
@ -277,78 +285,70 @@ QPDF::pushInheritedAttributesToPageInternal(
void
QPDF::updateObjectMaps(
ObjUser const& ou,
QPDFObjectHandle oh,
ObjUser const& first_ou,
QPDFObjectHandle first_oh,
std::function<int(QPDFObjectHandle&)> skip_stream_parameters)
{
QPDFObjGen::set visited;
updateObjectMapsInternal(ou, oh, skip_stream_parameters, visited, true);
}
void
QPDF::updateObjectMapsInternal(
ObjUser const& ou,
QPDFObjectHandle oh,
std::function<int(QPDFObjectHandle&)> skip_stream_parameters,
QPDFObjGen::set& visited,
bool top)
{
std::vector<UpdateObjectMapsFrame> pending;
pending.emplace_back(first_ou, first_oh, true);
// Traverse the object tree from this point taking care to avoid crossing page boundaries.
std::unique_ptr<ObjUser> thumb_ou;
while (!pending.empty()) {
auto cur = pending.back();
pending.pop_back();
bool is_page_node = false;
bool is_page_node = false;
if (oh.isDictionaryOfType("/Page")) {
is_page_node = true;
if (!top) {
return;
}
}
if (oh.isIndirect()) {
QPDFObjGen og(oh.getObjGen());
if (!visited.add(og)) {
QTC::TC("qpdf", "QPDF opt loop detected");
return;
}
m->obj_user_to_objects[ou].insert(og);
m->object_to_obj_users[og].insert(ou);
}
if (oh.isArray()) {
int n = oh.getArrayNItems();
for (int i = 0; i < n; ++i) {
updateObjectMapsInternal(
ou, oh.getArrayItem(i), skip_stream_parameters, visited, false);
}
} else if (oh.isDictionary() || oh.isStream()) {
QPDFObjectHandle dict = oh;
bool is_stream = oh.isStream();
int ssp = 0;
if (is_stream) {
dict = oh.getDict();
if (skip_stream_parameters) {
ssp = skip_stream_parameters(oh);
if (cur.oh.isDictionaryOfType("/Page")) {
is_page_node = true;
if (!cur.top) {
continue;
}
}
for (auto const& key: dict.getKeys()) {
if (is_page_node && (key == "/Thumb")) {
// Traverse page thumbnail dictionaries as a special case.
updateObjectMapsInternal(
ObjUser(ObjUser::ou_thumb, ou.pageno),
dict.getKey(key),
skip_stream_parameters,
visited,
false);
} else if (is_page_node && (key == "/Parent")) {
// Don't traverse back up the page tree
} else if (
((ssp >= 1) && (key == "/Length")) ||
((ssp >= 2) && ((key == "/Filter") || (key == "/DecodeParms")))) {
// Don't traverse into stream parameters that we are not going to write.
} else {
updateObjectMapsInternal(
ou, dict.getKey(key), skip_stream_parameters, visited, false);
if (cur.oh.isIndirect()) {
QPDFObjGen og(cur.oh.getObjGen());
if (!visited.add(og)) {
QTC::TC("qpdf", "QPDF opt loop detected");
continue;
}
m->obj_user_to_objects[cur.ou].insert(og);
m->object_to_obj_users[og].insert(cur.ou);
}
if (cur.oh.isArray()) {
int n = cur.oh.getArrayNItems();
for (int i = 0; i < n; ++i) {
pending.emplace_back(cur.ou, cur.oh.getArrayItem(i), false);
}
} else if (cur.oh.isDictionary() || cur.oh.isStream()) {
QPDFObjectHandle dict = cur.oh;
bool is_stream = cur.oh.isStream();
int ssp = 0;
if (is_stream) {
dict = cur.oh.getDict();
if (skip_stream_parameters) {
ssp = skip_stream_parameters(cur.oh);
}
}
for (auto const& key: dict.getKeys()) {
if (is_page_node && (key == "/Thumb")) {
// Traverse page thumbnail dictionaries as a special case. There can only ever
// be one /Thumb key on a page, and we see at most one page node per call.
thumb_ou = std::make_unique<ObjUser>(ObjUser::ou_thumb, cur.ou.pageno);
pending.emplace_back(*thumb_ou, dict.getKey(key), false);
} else if (is_page_node && (key == "/Parent")) {
// Don't traverse back up the page tree
} else if (
((ssp >= 1) && (key == "/Length")) ||
((ssp >= 2) && ((key == "/Filter") || (key == "/DecodeParms")))) {
// Don't traverse into stream parameters that we are not going to write.
} else {
pending.emplace_back(
cur.ou, dict.getKey(key), false);
}
}
}
}