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>

2 files changed, 2 insertions, 2 deletions

diff --git a/core/fxcodec/bmp/cfx_bmpdecompressor.cpp b/core/fxcodec/bmp/cfx_bmpdecompressor.cpp
index 56f11fd4cb..71909d2732 100644
--- a/core/fxcodec/bmp/cfx_bmpdecompressor.cpp
+++ b/core/fxcodec/bmp/cfx_bmpdecompressor.cpp
@@ -649,7 +649,7 @@ void CFX_BmpDecompressor::SetInputBuffer(uint8_t* src_buf, uint32_t src_size) {
       pdfium::MakeRetain<CFX_MemoryStream>(src_buf, src_size, false);
 }
 
-uint32_t CFX_BmpDecompressor::GetAvailInput(uint8_t** avail_buf) {
+FX_FILESIZE CFX_BmpDecompressor::GetAvailInput(uint8_t** avail_buf) {
   if (!input_buffer_)
     return 0;
 
diff --git a/core/fxcodec/bmp/cfx_bmpdecompressor.h b/core/fxcodec/bmp/cfx_bmpdecompressor.h
index eece78c7ca..152a2bd0ee 100644
--- a/core/fxcodec/bmp/cfx_bmpdecompressor.h
+++ b/core/fxcodec/bmp/cfx_bmpdecompressor.h
@@ -25,7 +25,7 @@ class CFX_BmpDecompressor {
   int32_t DecodeImage();
   int32_t ReadHeader();
   void SetInputBuffer(uint8_t* src_buf, uint32_t src_size);
-  uint32_t GetAvailInput(uint8_t** avail_buf);
+  FX_FILESIZE GetAvailInput(uint8_t** avail_buf);
 
   jmp_buf jmpbuf_;