in the attempt to fix 627393, changed IFX_FileRead's readBlock to return the length it reads

core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp b/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
index a8cbeaf5d4e3544473b089f614e28ce6099ee4ce..964df647efffdd3ffdf6a27895f36b3571363735 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_data_avail.cpp
@@ -1074,7 +1074,9 @@ FX_BOOL CPDF_DataAvail::GetNextChar(uint8_t& ch) {
     if ((FX_FILESIZE)(read_pos + read_size) > m_dwFileLen)
       read_pos = m_dwFileLen - read_size;
 
-    if (!m_pFileRead->ReadBlock(m_bufferData, read_pos, read_size))
+    if (m_pFileRead->ReadBlock(m_bufferData, read_pos, read_size) !=
+            read_size &&
+        !m_pFileRead->IsEOF())
       return FALSE;
 
     m_bufferOffset = read_pos;
@@ -1187,7 +1189,8 @@ FX_BOOL CPDF_DataAvail::CheckTrailer(DownloadHints* pHints) {
       return FALSE;
     }
 
-    if (!m_pFileRead->ReadBlock(pBuf, m_dwTrailerOffset, iSize))
+    if (m_pFileRead->ReadBlock(pBuf, m_dwTrailerOffset, iSize) != iSize &&

[Tom Sepez, 2016/10/19 23:12:47]

this may trigger a signed/unsigned comparision warning on some compilers.  iSize
may need to be uint32_t, along with a check for underflow at line 1184.  

+        !m_pFileRead->IsEOF())
       return FALSE;
 
     ScopedFileStream file(FX_CreateMemoryStream(pBuf, (size_t)iSize, FALSE));