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In QPDFParser::parse refactor handling of dict_close tokens

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This commit is contained in:
m-holger 2023-10-27 17:41:36 +01:00
parent 12837f14b6
commit 90829228b8
2 changed files with 76 additions and 85 deletions
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159
libqpdf/QPDFParser.cc
View File

@ -138,7 +138,80 @@ QPDFParser::parse(bool& empty, bool content_stream)
case QPDFTokenizer::tt_dict_close:
if (state == st_dictionary) {
state = st_stop;
if ((state_stack.size() < 2) || (stack.size() < 2)) {
throw std::logic_error("QPDFParser::parseInternal: st_stop encountered with "
"insufficient elements in stack");
}
// Convert list to map. Alternating elements are keys. Attempt to recover more or
// less gracefully from invalid dictionaries.
std::set<std::string> names;
for (auto& obj: olist) {
if (obj) {
if (obj->getTypeCode() == ::ot_name) {
names.insert(obj->getStringValue());
}
}
}
std::map<std::string, QPDFObjectHandle> dict;
int next_fake_key = 1;
for (auto iter = olist.begin(); iter != olist.end();) {
// Calculate key.
std::string key;
if (*iter && (*iter)->getTypeCode() == ::ot_name) {
key = (*iter)->getStringValue();
++iter;
} else {
for (bool found_fake = false; !found_fake;) {
key = "/QPDFFake" + std::to_string(next_fake_key++);
found_fake = (names.count(key) == 0);
QTC::TC("qpdf", "QPDFParser found fake", (found_fake ? 0 : 1));
}
warn(
offset,
"expected dictionary key but found non-name object; inserting key " +
key);
}
if (dict.count(key) > 0) {
QTC::TC("qpdf", "QPDFParser duplicate dict key");
warn(
offset,
"dictionary has duplicated key " + key +
"; last occurrence overrides earlier ones");
}
// Calculate value.
std::shared_ptr<QPDFObject> val;
if (iter != olist.end()) {
val = *iter;
++iter;
} else {
QTC::TC("qpdf", "QPDFParser no val for last key");
warn(
offset,
"dictionary ended prematurely; using null as value for last key");
val = QPDF_Null::create();
}
dict[std::move(key)] = std::move(val);
}
if (!frame.contents_string.empty() && dict.count("/Type") &&
dict["/Type"].isNameAndEquals("/Sig") && dict.count("/ByteRange") &&
dict.count("/Contents") && dict["/Contents"].isString()) {
dict["/Contents"] = QPDFObjectHandle::newString(frame.contents_string);
dict["/Contents"].setParsedOffset(frame.contents_offset);
}
object = QPDF_Dictionary::create(std::move(dict));
setDescription(object, offset - 2);
// The `offset` points to the next of "<<". Set the rewind offset to point to the
// beginning of "<<". This has been explicitly tested with whitespace surrounding
// the dictionary start delimiter. getLastOffset points to the dictionary end token
// and therefore can't be used here.
set_offset = true;
state_stack.pop_back();
state = state_stack.back();
stack.pop_back();
} else {
QTC::TC("qpdf", "QPDFParser bad dictionary close");
warn("unexpected dictionary close token");
@ -276,7 +349,7 @@ QPDFParser::parse(bool& empty, bool content_stream)
break;
}
if (object == nullptr && !is_null && (!(state == st_start || state == st_stop))) {
if (object == nullptr && !is_null && state != st_start) {
throw std::logic_error("QPDFParser:parseInternal: unexpected uninitialized object");
}
@ -299,88 +372,6 @@ QPDFParser::parse(bool& empty, bool content_stream)
case st_start:
break;
case st_stop:
if ((state_stack.size() < 2) || (stack.size() < 2)) {
throw std::logic_error("QPDFParser::parseInternal: st_stop encountered with "
"insufficient elements in stack");
}
parser_state_e old_state = state_stack.back();
state_stack.pop_back();
if (old_state == st_dictionary) {
// Convert list to map. Alternating elements are keys. Attempt to recover more or
// less gracefully from invalid dictionaries.
std::set<std::string> names;
for (auto& obj: olist) {
if (obj) {
if (obj->getTypeCode() == ::ot_name) {
names.insert(obj->getStringValue());
}
}
}
std::map<std::string, QPDFObjectHandle> dict;
int next_fake_key = 1;
for (auto iter = olist.begin(); iter != olist.end();) {
// Calculate key.
std::string key;
if (*iter && (*iter)->getTypeCode() == ::ot_name) {
key = (*iter)->getStringValue();
++iter;
} else {
for (bool found_fake = false; !found_fake;) {
key = "/QPDFFake" + std::to_string(next_fake_key++);
found_fake = (names.count(key) == 0);
QTC::TC("qpdf", "QPDFParser found fake", (found_fake ? 0 : 1));
}
warn(
offset,
"expected dictionary key but found non-name object; inserting key " +
key);
}
if (dict.count(key) > 0) {
QTC::TC("qpdf", "QPDFParser duplicate dict key");
warn(
offset,
"dictionary has duplicated key " + key +
"; last occurrence overrides earlier ones");
}
// Calculate value.
std::shared_ptr<QPDFObject> val;
if (iter != olist.end()) {
val = *iter;
++iter;
} else {
QTC::TC("qpdf", "QPDFParser no val for last key");
warn(
offset,
"dictionary ended prematurely; using null as value for last key");
val = QPDF_Null::create();
}
dict[std::move(key)] = std::move(val);
}
if (!frame.contents_string.empty() && dict.count("/Type") &&
dict["/Type"].isNameAndEquals("/Sig") && dict.count("/ByteRange") &&
dict.count("/Contents") && dict["/Contents"].isString()) {
dict["/Contents"] = QPDFObjectHandle::newString(frame.contents_string);
dict["/Contents"].setParsedOffset(frame.contents_offset);
}
object = QPDF_Dictionary::create(std::move(dict));
setDescription(object, offset - 2);
// The `offset` points to the next of "<<". Set the rewind offset to point to the
// beginning of "<<". This has been explicitly tested with whitespace surrounding
// the dictionary start delimiter. getLastOffset points to the dictionary end token
// and therefore can't be used here.
set_offset = true;
}
stack.pop_back();
if (state_stack.back() == st_top) {
done = true;
} else {
stack.back().olist.push_back(object);
}
}
}

2
libqpdf/qpdf/QPDFParser.hh
View File

@ -31,7 +31,7 @@ class QPDFParser
QPDFObjectHandle parse(bool& empty, bool content_stream);
private:
enum parser_state_e { st_top, st_start, st_stop, st_dictionary, st_array };
enum parser_state_e { st_top, st_start, st_dictionary, st_array };
bool tooManyBadTokens();
void warn(qpdf_offset_t offset, std::string const& msg) const;