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Add new private method QPDF::processXRefW

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This commit is contained in:
m-holger 2024-05-22 12:36:01 +01:00
parent 0186d60dcf
commit f74b28f0d1
2 changed files with 37 additions and 21 deletions
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2
include/qpdf/QPDF.hh
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@ -1028,6 +1028,8 @@ class QPDF
qpdf_offset_t read_xrefTable(qpdf_offset_t offset);
qpdf_offset_t read_xrefStream(qpdf_offset_t offset);
qpdf_offset_t processXRefStream(qpdf_offset_t offset, QPDFObjectHandle& xref_stream);
std::pair<size_t, std::array<int, 3>>
processXRefW(QPDFObjectHandle& dict, std::function<QPDFExc(std::string_view)> damaged);
std::pair<size_t, std::vector<long long>> processXRefIndex(
QPDFObjectHandle& dict,
size_t entry_size,

56
libqpdf/QPDF.cc
View File

@ -968,6 +968,36 @@ QPDF::read_xrefStream(qpdf_offset_t xref_offset)
return 0; // unreachable
}
// Return the entry size of the xref stream and the processed W array.
std::pair<size_t, std::array<int, 3>>
QPDF::processXRefW(QPDFObjectHandle& dict, std::function<QPDFExc(std::string_view)> damaged)
{
auto W_obj = dict.getKey("/W");
if (!(W_obj.isArray() && (W_obj.getArrayNItems() >= 3) && W_obj.getArrayItem(0).isInteger() &&
W_obj.getArrayItem(1).isInteger() && W_obj.getArrayItem(2).isInteger())) {
throw damaged("Cross-reference stream does not have a proper /W key");
}
std::array<int, 3> W;
int entry_size = 0;
auto w_vector = W_obj.getArrayAsVector();
int max_bytes = sizeof(qpdf_offset_t);
for (size_t i = 0; i < 3; ++i) {
W[i] = w_vector[i].getIntValueAsInt();
if (W[i] > max_bytes) {
throw damaged("Cross-reference stream's /W contains impossibly large values");
}
if (W[i] < 0) {
throw damaged("Cross-reference stream's /W contains negative values");
}
entry_size += W[i];
}
if (entry_size == 0) {
throw damaged("Cross-reference stream's /W indicates entry size of 0");
}
return {toS(entry_size), W};
}
// Return the expected size of the xref stream and the processed Index array.
std::pair<size_t, std::vector<long long>>
QPDF::processXRefIndex(
@ -1033,28 +1063,12 @@ QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj)
};
auto dict = xref_obj.getDict();
auto W_obj = dict.getKey("/W");
auto Size_obj = dict.getKey("/Size");
if (!(W_obj.isArray() && (W_obj.getArrayNItems() >= 3) && W_obj.getArrayItem(0).isInteger() &&
W_obj.getArrayItem(1).isInteger() && W_obj.getArrayItem(2).isInteger() &&
Size_obj.isInteger())) {
throw damaged("Cross-reference stream does not have a proper /W key");
}
int W[3];
size_t entry_size = 0;
int max_bytes = sizeof(qpdf_offset_t);
for (int i = 0; i < 3; ++i) {
W[i] = W_obj.getArrayItem(i).getIntValueAsInt();
if (W[i] > max_bytes) {
throw damaged("Cross-reference stream's /W contains impossibly large values");
}
entry_size += toS(W[i]);
}
if (entry_size == 0) {
throw damaged("Cross-reference stream's /W indicates entry size of 0");
if (!Size_obj.isInteger()) {
throw damaged("Cross-reference stream does not have a proper /Size key");
}
auto [entry_size, W] = processXRefW(dict, damaged);
auto [expected_size, indx] = processXRefIndex(dict, entry_size, damaged);
std::shared_ptr<Buffer> bp = xref_obj.getStreamData(qpdf_dl_specialized);
@ -1090,8 +1104,8 @@ QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj)
throw std::range_error(msg.str());
}
// Read this entry
qpdf_offset_t fields[3];
for (int j = 0; j < 3; ++j) {
std::array<qpdf_offset_t, 3> fields;
for (size_t j = 0; j < 3; ++j) {
fields[j] = 0;
if ((j == 0) && (W[0] == 0)) {
QTC::TC("qpdf", "QPDF default for xref stream field 0");