Make CCodec_ProgressiveDecoder::ReadMoreData() slightly saner
- Fix buffer leak if TryRealloc fails.
- Make m_SrcSize always represent the usable bytes in the buffer, even
when read the last partial block from the file.
- Remove redundant comparisons and use std::min().
- Better naming.
Change-Id: Ie7dd79bac21b2f2422f299563a2dd28ed358e3e2
Reviewed-on: https://pdfium-review.googlesource.com/42130
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcodec/codec/ccodec_progressivedecoder.cpp b/core/fxcodec/codec/ccodec_progressivedecoder.cpp
index 6e9b954..27a2494 100644
--- a/core/fxcodec/codec/ccodec_progressivedecoder.cpp
+++ b/core/fxcodec/codec/ccodec_progressivedecoder.cpp
@@ -1595,46 +1595,51 @@
CodecModuleIface::Context* pContext,
bool invalidate_buffer,
FXCODEC_STATUS& err_status) {
- if (static_cast<uint32_t>(m_pFile->GetSize()) <= m_offSet)
+ // Check for EOF.
+ if (m_offSet >= static_cast<uint32_t>(m_pFile->GetSize()))
return false;
- uint32_t dwFileRemaining = m_pFile->GetSize() - m_offSet;
- uint32_t dwAmountToFetchFromFile = dwFileRemaining;
- uint32_t dwUnusedBuffer = 0;
+ // Try to get whatever remains.
+ uint32_t dwBytesToFetchFromFile = m_pFile->GetSize() - m_offSet;
+
+ // Figure out if the codec stopped processing midway through the buffer.
+ uint32_t dwUnconsumed = 0;
if (!invalidate_buffer) {
FX_SAFE_UINT32 avail_input = pModule->GetAvailInput(pContext);
if (!avail_input.IsValid())
return false;
- dwUnusedBuffer = avail_input.ValueOrDie();
+ dwUnconsumed = avail_input.ValueOrDie();
}
- if (dwUnusedBuffer == m_SrcSize) {
- if (dwFileRemaining > FXCODEC_BLOCK_SIZE)
- dwAmountToFetchFromFile = FXCODEC_BLOCK_SIZE;
- m_SrcSize = std::min(
- (dwAmountToFetchFromFile + dwUnusedBuffer + FXCODEC_BLOCK_SIZE - 1) /
- FXCODEC_BLOCK_SIZE * FXCODEC_BLOCK_SIZE,
- static_cast<uint32_t>(m_pFile->GetSize()));
- m_pSrcBuf.reset(FX_TryRealloc(uint8_t, m_pSrcBuf.release(), m_SrcSize));
- if (!m_pSrcBuf) {
+
+ if (dwUnconsumed == m_SrcSize) {
+ // Codec couldn't make any progress against the bytes in the buffer.
+ // Increase the buffer size so that there might be enough contiguous
+ // bytes to allow whatever operation is having difficulty to succeed.
+ dwBytesToFetchFromFile =
+ std::min<uint32_t>(dwBytesToFetchFromFile, FXCODEC_BLOCK_SIZE);
+ uint32_t dwNewSize = m_SrcSize + dwBytesToFetchFromFile;
+ uint8_t* pNewBuf = FX_TryRealloc(uint8_t, m_pSrcBuf.release(), dwNewSize);
+ if (!pNewBuf) {
err_status = FXCODEC_STATUS_ERR_MEMORY;
return false;
}
+ m_SrcSize = dwNewSize;
+ m_pSrcBuf.reset(pNewBuf);
} else {
- uint32_t dwConsumed = m_SrcSize - dwUnusedBuffer;
- if (dwUnusedBuffer)
- memmove(m_pSrcBuf.get(), m_pSrcBuf.get() + dwConsumed, dwUnusedBuffer);
- if (dwFileRemaining > dwConsumed)
- dwAmountToFetchFromFile = dwConsumed;
+ uint32_t dwConsumed = m_SrcSize - dwUnconsumed;
+ memmove(m_pSrcBuf.get(), m_pSrcBuf.get() + dwConsumed, dwUnconsumed);
+ dwBytesToFetchFromFile = std::min(dwBytesToFetchFromFile, dwConsumed);
+ m_SrcSize = dwBytesToFetchFromFile + dwUnconsumed;
}
- if (!m_pFile->ReadBlock(m_pSrcBuf.get() + dwUnusedBuffer, m_offSet,
- dwAmountToFetchFromFile)) {
+
+ // Append new data past the bytes not yet processed by the codec.
+ if (!m_pFile->ReadBlock(m_pSrcBuf.get() + dwUnconsumed, m_offSet,
+ dwBytesToFetchFromFile)) {
err_status = FXCODEC_STATUS_ERR_READ;
return false;
}
- m_offSet += dwAmountToFetchFromFile;
- return pModule->Input(
- pContext, {m_pSrcBuf.get(), dwAmountToFetchFromFile + dwUnusedBuffer},
- nullptr);
+ m_offSet += dwBytesToFetchFromFile;
+ return pModule->Input(pContext, {m_pSrcBuf.get(), m_SrcSize}, nullptr);
}
FXCODEC_STATUS CCodec_ProgressiveDecoder::LoadImageInfo(
