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-rw-r--r--core/fpdfapi/parser/cpdf_syntax_parser.cpp175
-rw-r--r--core/fpdfapi/parser/cpdf_syntax_parser.h2
2 files changed, 92 insertions, 85 deletions
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser.cpp b/core/fpdfapi/parser/cpdf_syntax_parser.cpp
index afdac58257..00eed49300 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_syntax_parser.cpp
@@ -518,6 +518,56 @@ unsigned int CPDF_SyntaxParser::ReadEOLMarkers(FX_FILESIZE pos) {
return 0;
}
+FX_FILESIZE CPDF_SyntaxParser::FindWordPos(const ByteStringView& word) {
+ AutoRestorer<FX_FILESIZE> pos_restorer(&m_Pos);
+ FX_FILESIZE end_offset = FindTag(word, 0);
+ while (end_offset >= 0) {
+ // Stop searching when word is found.
+ if (IsWholeWord(GetPos() - word.GetLength(), m_FileLen, word, true))
+ return GetPos() - word.GetLength();
+
+ end_offset = FindTag(word, 0);
+ }
+ return -1;
+}
+
+FX_FILESIZE CPDF_SyntaxParser::FindStreamEndPos() {
+ const ByteStringView kEndStreamStr("endstream");
+ const ByteStringView kEndObjStr("endobj");
+
+ FX_FILESIZE endStreamWordOffset = FindWordPos(kEndStreamStr);
+ FX_FILESIZE endObjWordOffset = FindWordPos(kEndObjStr);
+
+ // Can't find "endstream" or "endobj".
+ if (endStreamWordOffset < 0 && endObjWordOffset < 0) {
+ return -1;
+ }
+
+ if (endStreamWordOffset < 0 && endObjWordOffset >= 0) {
+ // Correct the position of end stream.
+ endStreamWordOffset = endObjWordOffset;
+ } else if (endStreamWordOffset >= 0 && endObjWordOffset < 0) {
+ // Correct the position of end obj.
+ endObjWordOffset = endStreamWordOffset;
+ } else if (endStreamWordOffset > endObjWordOffset) {
+ endStreamWordOffset = endObjWordOffset;
+ }
+
+ int numMarkers = ReadEOLMarkers(endStreamWordOffset - 2);
+ if (numMarkers == 2) {
+ endStreamWordOffset -= 2;
+ } else {
+ numMarkers = ReadEOLMarkers(endStreamWordOffset - 1);
+ if (numMarkers == 1) {
+ endStreamWordOffset -= 1;
+ }
+ }
+ if (endStreamWordOffset < GetPos()) {
+ return -1;
+ }
+ return endStreamWordOffset;
+}
+
std::unique_ptr<CPDF_Stream> CPDF_SyntaxParser::ReadStream(
std::unique_ptr<CPDF_Dictionary> pDict) {
const CPDF_Number* pLenObj = ToNumber(pDict->GetDirectObjectFor("Length"));
@@ -525,113 +575,68 @@ std::unique_ptr<CPDF_Stream> CPDF_SyntaxParser::ReadStream(
// Locate the start of stream.
ToNextLine();
- FX_FILESIZE streamStartPos = GetPos();
+ const FX_FILESIZE streamStartPos = GetPos();
+
+ std::unique_ptr<uint8_t, FxFreeDeleter> pData;
+ if (len > 0) {
+ FX_SAFE_FILESIZE pos = GetPos();
+ pos += len;
+ if (!pos.IsValid() || pos.ValueOrDie() >= m_FileLen)
+ len = -1;
+ }
+
+ if (len > 0) {
+ pData.reset(FX_Alloc(uint8_t, len));
+ // We should try read data first to allow the Validator to request data
+ // smoothly, without jumps.
+ if (!ReadBlock(pData.get(), len))
+ return nullptr;
+ }
const ByteStringView kEndStreamStr("endstream");
const ByteStringView kEndObjStr("endobj");
- bool bSearchForKeyword = true;
+ // Note, we allow zero length streams as we need to pass them through when we
+ // are importing pages into a new document.
if (len >= 0) {
- pdfium::base::CheckedNumeric<FX_FILESIZE> pos = GetPos();
- pos += len;
- if (pos.IsValid() && pos.ValueOrDie() < m_FileLen)
- m_Pos = pos.ValueOrDie();
-
+ const CPDF_ReadValidator::Session read_session(GetValidator().Get());
m_Pos += ReadEOLMarkers(GetPos());
memset(m_WordBuffer, 0, kEndStreamStr.GetLength() + 1);
GetNextWordInternal(nullptr);
+ if (GetValidator()->has_read_problems())
+ return nullptr;
+
// Earlier version of PDF specification doesn't require EOL marker before
// 'endstream' keyword. If keyword 'endstream' follows the bytes in
// specified length, it signals the end of stream.
if (memcmp(m_WordBuffer, kEndStreamStr.raw_str(),
- kEndStreamStr.GetLength()) == 0) {
- bSearchForKeyword = false;
+ kEndStreamStr.GetLength()) != 0) {
+ pData.reset();
+ len = -1;
+ SetPos(streamStartPos);
}
}
- if (bSearchForKeyword) {
- // If len is not available, len needs to be calculated
+ if (len < 0) {
+ // If len is not available or incorrect, len needs to be calculated
// by searching the keywords "endstream" or "endobj".
- m_Pos = streamStartPos;
- FX_FILESIZE endStreamOffset = 0;
- while (endStreamOffset >= 0) {
- endStreamOffset = FindTag(kEndStreamStr, 0);
-
- // Can't find "endstream".
- if (endStreamOffset < 0)
- break;
-
- // Stop searching when "endstream" is found.
- if (IsWholeWord(GetPos() - kEndStreamStr.GetLength(), m_FileLen,
- kEndStreamStr, true)) {
- endStreamOffset = GetPos() - streamStartPos - kEndStreamStr.GetLength();
- break;
- }
- }
-
- m_Pos = streamStartPos;
- FX_FILESIZE endObjOffset = 0;
- while (endObjOffset >= 0) {
- endObjOffset = FindTag(kEndObjStr, 0);
-
- // Can't find "endobj".
- if (endObjOffset < 0)
- break;
-
- // Stop searching when "endobj" is found.
- if (IsWholeWord(GetPos() - kEndObjStr.GetLength(), m_FileLen, kEndObjStr,
- true)) {
- endObjOffset = GetPos() - streamStartPos - kEndObjStr.GetLength();
- break;
- }
- }
-
- // Can't find "endstream" or "endobj".
- if (endStreamOffset < 0 && endObjOffset < 0)
+ const FX_FILESIZE streamEndPos = FindStreamEndPos();
+ if (streamEndPos < 0)
return nullptr;
- if (endStreamOffset < 0 && endObjOffset >= 0) {
- // Correct the position of end stream.
- endStreamOffset = endObjOffset;
- } else if (endStreamOffset >= 0 && endObjOffset < 0) {
- // Correct the position of end obj.
- endObjOffset = endStreamOffset;
- } else if (endStreamOffset > endObjOffset) {
- endStreamOffset = endObjOffset;
- }
- len = endStreamOffset;
-
- int numMarkers = ReadEOLMarkers(streamStartPos + endStreamOffset - 2);
- if (numMarkers == 2) {
- len -= 2;
- } else {
- numMarkers = ReadEOLMarkers(streamStartPos + endStreamOffset - 1);
- if (numMarkers == 1) {
- len -= 1;
- }
+ len = streamEndPos - streamStartPos;
+ ASSERT(len >= 0);
+ if (len > 0) {
+ SetPos(streamStartPos);
+ pData.reset(FX_Alloc(uint8_t, len));
+ if (!ReadBlock(pData.get(), len))
+ return nullptr;
}
- if (len < 0)
- return nullptr;
-
- pDict->SetNewFor<CPDF_Number>("Length", static_cast<int>(len));
}
- m_Pos = streamStartPos;
-
- // Read up to the end of the buffer. Note, we allow zero length streams as
- // we need to pass them through when we are importing pages into a new
- // document.
- len = std::min(len, m_FileLen - GetPos() - m_HeaderOffset);
- if (len < 0)
- return nullptr;
- std::unique_ptr<uint8_t, FxFreeDeleter> pData;
- if (len > 0) {
- pData.reset(FX_Alloc(uint8_t, len));
- ReadBlock(pData.get(), len);
- }
auto pStream =
pdfium::MakeUnique<CPDF_Stream>(std::move(pData), len, std::move(pDict));
- streamStartPos = GetPos();
+ const FX_FILESIZE end_stream_offset = GetPos();
memset(m_WordBuffer, 0, kEndObjStr.GetLength() + 1);
GetNextWordInternal(nullptr);
@@ -639,7 +644,7 @@ std::unique_ptr<CPDF_Stream> CPDF_SyntaxParser::ReadStream(
if (m_WordSize == static_cast<unsigned int>(kEndObjStr.GetLength()) &&
numMarkers != 0 &&
memcmp(m_WordBuffer, kEndObjStr.raw_str(), kEndObjStr.GetLength()) == 0) {
- m_Pos = streamStartPos;
+ SetPos(end_stream_offset);
}
return pStream;
}
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser.h b/core/fpdfapi/parser/cpdf_syntax_parser.h
index a8f6bb2033..a29d631c95 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser.h
+++ b/core/fpdfapi/parser/cpdf_syntax_parser.h
@@ -87,6 +87,8 @@ class CPDF_SyntaxParser {
ByteString ReadString();
ByteString ReadHexString();
unsigned int ReadEOLMarkers(FX_FILESIZE pos);
+ FX_FILESIZE FindWordPos(const ByteStringView& word);
+ FX_FILESIZE FindStreamEndPos();
std::unique_ptr<CPDF_Stream> ReadStream(
std::unique_ptr<CPDF_Dictionary> pDict);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-01 05:13:50 +0000