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

core/fxcrt/fx_extension.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/fxcrt/extension.h"
 
 #include <utility>
 
@@ skipping 86 matching lines @@
     return;
   }
   delete this;
 }
 
 FX_FILESIZE CFX_MemoryStream::GetSize() {
   return (FX_FILESIZE)m_nCurSize;
 }
 
 bool CFX_MemoryStream::IsEOF() {
-  return m_nCurPos >= (size_t)GetSize();
+  return m_nCurPos >= pdfium::base::checked_cast<size_t>(GetSize());
 }
 
 FX_FILESIZE CFX_MemoryStream::GetPosition() {
   return (FX_FILESIZE)m_nCurPos;
 }
 
-bool CFX_MemoryStream::ReadBlock(void* buffer,
-                                 FX_FILESIZE offset,
-                                 size_t size) {
+size_t CFX_MemoryStream::ReadBlock(void* buffer,
+                                   FX_FILESIZE offset,
+                                   size_t size) {
   if (!buffer || !size)
-    return false;
+    return 0;
 
   FX_SAFE_SIZE_T newPos = size;
   newPos += offset;
   if (!newPos.IsValid() || newPos.ValueOrDefault(0) == 0 ||
       newPos.ValueOrDie() > m_nCurSize) {
-    return false;
+    return 0;
   }
 
   m_nCurPos = newPos.ValueOrDie();
   if (m_dwFlags & FX_MEMSTREAM_Consecutive) {
     FXSYS_memcpy(buffer, m_Blocks[0] + (size_t)offset, size);
-    return true;
+    return size;
   }
+  size_t readSize = size;
   size_t nStartBlock = (size_t)offset / m_nGrowSize;
   offset -= (FX_FILESIZE)(nStartBlock * m_nGrowSize);
   while (size) {
     size_t nRead = m_nGrowSize - (size_t)offset;
     if (nRead > size) {
       nRead = size;
     }
     FXSYS_memcpy(buffer, m_Blocks[(int)nStartBlock] + (size_t)offset, nRead);
     buffer = ((uint8_t*)buffer) + nRead;
     size -= nRead;
     nStartBlock++;
     offset = 0;
   }
-  return true;
+  return readSize;
 }
 
 size_t CFX_MemoryStream::ReadBlock(void* buffer, size_t size) {
   if (m_nCurPos >= m_nCurSize) {
     return 0;
   }
   size_t nRead = std::min(size, m_nCurSize - m_nCurPos);
-  if (!ReadBlock(buffer, (int32_t)m_nCurPos, nRead)) {
+  if (ReadBlock(buffer, (int32_t)m_nCurPos, nRead) != nRead && !IsEOF()) {
     return 0;
   }
   return nRead;
 }
 
 bool CFX_MemoryStream::WriteBlock(const void* buffer,
                                   FX_FILESIZE offset,
                                   size_t size) {
   if (!buffer || !size)
     return false;
@@ skipping 134 matching lines @@
 }
 
 bool CFX_CRTFileStream::IsEOF() {
   return GetPosition() >= GetSize();
 }
 
 FX_FILESIZE CFX_CRTFileStream::GetPosition() {
   return m_pFile->GetPosition();
 }
 
-bool CFX_CRTFileStream::ReadBlock(void* buffer,
-                                  FX_FILESIZE offset,
-                                  size_t size) {
-  return m_pFile->ReadPos(buffer, size, offset) > 0;
+size_t CFX_CRTFileStream::ReadBlock(void* buffer,
+                                    FX_FILESIZE offset,
+                                    size_t size) {
+  return m_pFile->ReadPos(buffer, size, offset);
 }
 
 size_t CFX_CRTFileStream::ReadBlock(void* buffer, size_t size) {
   return m_pFile->Read(buffer, size);
 }
 
 bool CFX_CRTFileStream::WriteBlock(const void* buffer,
                                    FX_FILESIZE offset,
                                    size_t size) {
   return !!m_pFile->WritePos(buffer, size, offset);
@@ skipping 288 matching lines @@
     b = ((const uint8_t*)pGUID)[i];
     *pBuf++ = gs_FX_pHexChars[b >> 4];
     *pBuf++ = gs_FX_pHexChars[b & 0x0F];
     if (bSeparator && (i == 3 || i == 5 || i == 7 || i == 9)) {
       *pBuf++ = L'-';
     }
   }
   bsStr.ReleaseBuffer(bSeparator ? 36 : 32);
 }
 #endif  // PDF_ENABLE_XFA