Change return value of GetAvailInput

This changes the return value from uint32_t to FX_FILESIZE, which is
the type the methods is uses return. The existing code does an
unguarded static cast, so something like -1 could cause a very large
value being returned.

This change has a cascading impact up to the top of the progressive
codec, which now has to handle negative values gracefully.

Change-Id: I813fb71e932dd5da014dbaed0dbf3bb28f8d4e9f
Reviewed-on: https://pdfium-review.googlesource.com/26450
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/core/fxcodec/codec/fx_codec_progress.cpp b/core/fxcodec/codec/fx_codec_progress.cpp
index 82b0168f6e..7e29524b2f 100644
--- a/core/fxcodec/codec/fx_codec_progress.cpp
+++ b/core/fxcodec/codec/fx_codec_progress.cpp
@@ -836,7 +836,12 @@ bool CCodec_ProgressiveDecoder::BmpReadMoreData(CCodec_BmpModule* pBmpModule,
     return false;
 
   dwSize = dwSize - m_offSet;
-  uint32_t dwAvail = pBmpModule->GetAvailInput(m_pBmpContext.get(), nullptr);
+  FX_SAFE_UINT32 avail_input =
+      pBmpModule->GetAvailInput(m_pBmpContext.get(), nullptr);
+  if (!avail_input.IsValid())
+    return false;
+
+  uint32_t dwAvail = avail_input.ValueOrDie();
   if (dwAvail == m_SrcSize) {
     if (dwSize > FXCODEC_BLOCK_SIZE) {
       dwSize = FXCODEC_BLOCK_SIZE;