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-rw-r--r--libqpdf/QPDF.cc253
1 files changed, 143 insertions, 110 deletions
diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 9554027c..7edb76f9 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -567,7 +567,7 @@ QPDF::reconstruct_xref(QPDFExc& e)
insertReconstructedXrefEntry(obj, token_start, gen);
}
} else if (!m->trailer.isInitialized() && t1.isWord("trailer")) {
- QPDFObjectHandle t = readObject(m->file, "trailer", QPDFObjGen(), false);
+ QPDFObjectHandle t = readTrailer();
if (!t.isDictionary()) {
// Oh well. It was worth a try.
} else {
@@ -855,7 +855,7 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
}
// Set offset to previous xref table if any
- QPDFObjectHandle cur_trailer = readObject(m->file, "trailer", QPDFObjGen(), false);
+ QPDFObjectHandle cur_trailer = readTrailer();
if (!cur_trailer.isDictionary()) {
QTC::TC("qpdf", "QPDF missing trailer");
throw damagedPDF("", "expected trailer dictionary");
@@ -1268,124 +1268,160 @@ QPDF::setLastObjectDescription(std::string const& description, QPDFObjGen const&
}
QPDFObjectHandle
-QPDF::readObject(
- std::shared_ptr<InputSource> input,
- std::string const& description,
- QPDFObjGen const& og,
- bool in_object_stream)
+QPDF::readTrailer()
{
- setLastObjectDescription(description, og);
- qpdf_offset_t offset = input->tell();
-
+ qpdf_offset_t offset = m->file->tell();
bool empty = false;
- std::shared_ptr<StringDecrypter> decrypter_ph;
- StringDecrypter* decrypter = nullptr;
- if (m->encp->encrypted && (!in_object_stream)) {
- decrypter_ph = std::make_shared<StringDecrypter>(this, og);
- decrypter = decrypter_ph.get();
+ auto object = QPDFParser(m->file, "trailer", m->tokenizer, nullptr, this).parse(empty, false);
+ if (empty) {
+ // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in
+ // actual PDF files and Adobe Reader appears to ignore them.
+ warn(damagedPDF("trailer", "empty object treated as null"));
+ } else if (object.isDictionary() && readToken(m->file).isWord("stream")) {
+ warn(damagedPDF("trailer", m->file->tell(), "stream keyword found in trailer"));
}
- auto object = QPDFParser(input, m->last_object_description, m->tokenizer, decrypter, this)
+ // Override last_offset so that it points to the beginning of the object we just read
+ m->file->setLastOffset(offset);
+ return object;
+}
+
+
+QPDFObjectHandle
+QPDF::readObject(std::string const& description, QPDFObjGen og)
+{
+ setLastObjectDescription(description, og);
+ qpdf_offset_t offset = m->file->tell();
+ bool empty = false;
+
+ StringDecrypter decrypter{this, og};
+ StringDecrypter* decrypter_ptr = m->encp->encrypted ? &decrypter : nullptr;
+ auto object = QPDFParser(m->file, m->last_object_description, m->tokenizer, decrypter_ptr, this)
.parse(empty, false);
if (empty) {
// Nothing in the PDF spec appears to allow empty objects, but they have been encountered in
// actual PDF files and Adobe Reader appears to ignore them.
- warn(damagedPDF(input, input->getLastOffset(), "empty object treated as null"));
- } else if (object.isDictionary() && (!in_object_stream)) {
- // check for stream
- qpdf_offset_t cur_offset = input->tell();
- if (readToken(input).isWord("stream")) {
- // The PDF specification states that the word "stream" should be followed by either a
- // carriage return and a newline or by a newline alone. It specifically disallowed
- // following it by a carriage return alone since, in that case, there would be no way to
- // tell whether the NL in a CR NL sequence was part of the stream data. However, some
- // readers, including Adobe reader, accept a carriage return by itself when followed by
- // a non-newline character, so that's what we do here. We have also seen files that have
- // extraneous whitespace between the stream keyword and the newline.
- bool done = false;
- while (!done) {
- done = true;
- char ch;
- if (input->read(&ch, 1) == 0) {
- // A premature EOF here will result in some other problem that will get reported
- // at another time.
- } else if (ch == '\n') {
- // ready to read stream data
- QTC::TC("qpdf", "QPDF stream with NL only");
- } else if (ch == '\r') {
- // Read another character
- if (input->read(&ch, 1) != 0) {
- if (ch == '\n') {
- // Ready to read stream data
- QTC::TC("qpdf", "QPDF stream with CRNL");
- } else {
- // Treat the \r by itself as the whitespace after endstream and start
- // reading stream data in spite of not having seen a newline.
- QTC::TC("qpdf", "QPDF stream with CR only");
- input->unreadCh(ch);
- warn(damagedPDF(
- input,
- input->tell(),
- "stream keyword followed by carriage return "
- "only"));
- }
- }
- } else if (QUtil::is_space(ch)) {
- warn(damagedPDF(
- input, input->tell(), "stream keyword followed by extraneous whitespace"));
- done = false;
- } else {
- QTC::TC("qpdf", "QPDF stream without newline");
- input->unreadCh(ch);
- warn(damagedPDF(
- input,
- input->tell(),
- "stream keyword not followed by proper line "
- "terminator"));
- }
- }
+ warn(damagedPDF(m->file, m->file->getLastOffset(), "empty object treated as null"));
+ return object;
+ }
+ auto token = readToken(m->file);
+ if (object.isDictionary() && token.isWord("stream")) {
+ readStream(object, og, offset);
+ token = readToken(m->file);
+ }
+ if (!token.isWord("endobj")) {
+ QTC::TC("qpdf", "QPDF err expected endobj");
+ warn(damagedPDF("expected endobj"));
+ }
+ return object;
+}
- // Must get offset before accessing any additional objects since resolving a previously
- // unresolved indirect object will change file position.
- qpdf_offset_t stream_offset = input->tell();
- size_t length = 0;
+// After reading stream dictionary and stream keyword, read rest of stream.
+void
+QPDF::readStream(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
+{
+ validateStreamLineEnd(object, og, offset);
- try {
- auto length_obj = object.getKey("/Length");
+ // Must get offset before accessing any additional objects since resolving a previously
+ // unresolved indirect object will change file position.
+ qpdf_offset_t stream_offset = m->file->tell();
+ size_t length = 0;
- if (!length_obj.isInteger()) {
- if (length_obj.isNull()) {
- QTC::TC("qpdf", "QPDF stream without length");
- throw damagedPDF(input, offset, "stream dictionary lacks /Length key");
- }
- QTC::TC("qpdf", "QPDF stream length not integer");
- throw damagedPDF(
- input, offset, "/Length key in stream dictionary is not an integer");
- }
+ try {
+ auto length_obj = object.getKey("/Length");
- length = toS(length_obj.getUIntValue());
- // Seek in two steps to avoid potential integer overflow
- input->seek(stream_offset, SEEK_SET);
- input->seek(toO(length), SEEK_CUR);
- if (!readToken(input).isWord("endstream")) {
- QTC::TC("qpdf", "QPDF missing endstream");
- throw damagedPDF(input, input->getLastOffset(), "expected endstream");
- }
- } catch (QPDFExc& e) {
- if (m->attempt_recovery) {
- warn(e);
- length = recoverStreamLength(input, og, stream_offset);
+ if (!length_obj.isInteger()) {
+ if (length_obj.isNull()) {
+ QTC::TC("qpdf", "QPDF stream without length");
+ throw damagedPDF(offset, "stream dictionary lacks /Length key");
+ }
+ QTC::TC("qpdf", "QPDF stream length not integer");
+ throw damagedPDF(offset, "/Length key in stream dictionary is not an integer");
+ }
+
+ length = toS(length_obj.getUIntValue());
+ // Seek in two steps to avoid potential integer overflow
+ m->file->seek(stream_offset, SEEK_SET);
+ m->file->seek(toO(length), SEEK_CUR);
+ if (!readToken(m->file).isWord("endstream")) {
+ QTC::TC("qpdf", "QPDF missing endstream");
+ throw damagedPDF("expected endstream");
+ }
+ } catch (QPDFExc& e) {
+ if (m->attempt_recovery) {
+ warn(e);
+ length = recoverStreamLength(m->file, og, stream_offset);
+ } else {
+ throw;
+ }
+ }
+ object = newIndirect(og, QPDF_Stream::create(this, og, object, stream_offset, length));
+}
+
+void
+QPDF::validateStreamLineEnd(QPDFObjectHandle& object, QPDFObjGen og, qpdf_offset_t offset)
+{
+ // The PDF specification states that the word "stream" should be followed by either a carriage
+ // return and a newline or by a newline alone. It specifically disallowed following it by a
+ // carriage return alone since, in that case, there would be no way to tell whether the NL in a
+ // CR NL sequence was part of the stream data. However, some readers, including Adobe reader,
+ // accept a carriage return by itself when followed by a non-newline character, so that's what
+ // we do here. We have also seen files that have extraneous whitespace between the stream
+ // keyword and the newline.
+ while (true) {
+ char ch;
+ if (m->file->read(&ch, 1) == 0) {
+ // A premature EOF here will result in some other problem that will get reported at
+ // another time.
+ return;
+ }
+ if (ch == '\n') {
+ // ready to read stream data
+ QTC::TC("qpdf", "QPDF stream with NL only");
+ return;
+ }
+ if (ch == '\r') {
+ // Read another character
+ if (m->file->read(&ch, 1) != 0) {
+ if (ch == '\n') {
+ // Ready to read stream data
+ QTC::TC("qpdf", "QPDF stream with CRNL");
} else {
- throw;
+ // Treat the \r by itself as the whitespace after endstream and start reading
+ // stream data in spite of not having seen a newline.
+ QTC::TC("qpdf", "QPDF stream with CR only");
+ m->file->unreadCh(ch);
+ warn(damagedPDF(
+ m->file->tell(), "stream keyword followed by carriage return only"));
}
}
- object = newIndirect(og, QPDF_Stream::create(this, og, object, stream_offset, length));
- } else {
- input->seek(cur_offset, SEEK_SET);
+ return;
}
+ if (!QUtil::is_space(ch)) {
+ QTC::TC("qpdf", "QPDF stream without newline");
+ m->file->unreadCh(ch);
+ warn(damagedPDF(
+ m->file->tell(), "stream keyword not followed by proper line terminator"));
+ return;
+ }
+ warn(damagedPDF(m->file->tell(), "stream keyword followed by extraneous whitespace"));
}
+}
- // Override last_offset so that it points to the beginning of the object we just read
- input->setLastOffset(offset);
+QPDFObjectHandle
+QPDF::readObjectInStream(std::shared_ptr<InputSource>& input, int obj)
+{
+ m->last_object_description.erase(7); // last_object_description starts with "object "
+ m->last_object_description += std::to_string(obj);
+ m->last_object_description += " 0";
+
+ bool empty = false;
+ auto object = QPDFParser(input, m->last_object_description, m->tokenizer, nullptr, this)
+ .parse(empty, false);
+ if (empty) {
+ // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in
+ // actual PDF files and Adobe Reader appears to ignore them.
+ warn(damagedPDF(input, input->getLastOffset(), "empty object treated as null"));
+ }
return object;
}
@@ -1559,12 +1595,7 @@ QPDF::readObjectAtOffset(
}
}
- QPDFObjectHandle oh = readObject(m->file, description, og, false);
-
- if (!readToken(m->file).isWord("endobj")) {
- QTC::TC("qpdf", "QPDF err expected endobj");
- warn(damagedPDF("expected endobj"));
- }
+ QPDFObjectHandle oh = readObject(description, og);
if (isUnresolved(og)) {
// Store the object in the cache here so it gets cached whether we first know the offset or
@@ -1744,13 +1775,15 @@ QPDF::resolveObjectsInStream(int obj_stream_number)
// found here in the cache. Remember that some objects stored here might have been overridden
// by new objects appended to the file, so it is necessary to recheck the xref table and only
// cache what would actually be resolved here.
+ m->last_object_description.clear();
+ m->last_object_description += "object ";
for (auto const& iter: offsets) {
QPDFObjGen og(iter.first, 0);
QPDFXRefEntry const& entry = 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);
+ QPDFObjectHandle oh = readObjectInStream(input, iter.first);
updateCache(og, oh.getObj(), end_before_space, end_after_space);
} else {
QTC::TC("qpdf", "QPDF not caching overridden objstm object");
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-09 22:38:51 +0200