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

 // Copyright 2016 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/fpdfapi/fpdf_parser/include/cpdf_data_avail.h"
 
 #include <algorithm>
 #include <memory>
@@ skipping 1056 matching lines @@
   if (m_bufferOffset >= pos ||
       (FX_FILESIZE)(m_bufferOffset + m_bufferSize) <= pos) {
     FX_FILESIZE read_pos = pos;
     uint32_t read_size = 512;
     if ((FX_FILESIZE)read_size > m_dwFileLen)
       read_size = (uint32_t)m_dwFileLen;
 
     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;
     m_bufferSize = read_size;
   }
   ch = m_bufferData[pos - m_bufferOffset];
   m_Pos++;
   return TRUE;
 }
 
@@ skipping 92 matching lines @@
       (int32_t)(m_Pos + 512 > m_dwFileLen ? m_dwFileLen - m_Pos : 512);
   if (m_pFileAvail->IsDataAvail(m_Pos, iTrailerSize)) {
     int32_t iSize = (int32_t)(m_Pos + iTrailerSize - m_dwTrailerOffset);
     CFX_BinaryBuf buf(iSize);
     uint8_t* pBuf = buf.GetBuffer();
     if (!pBuf) {
       m_docStatus = PDF_DATAAVAIL_ERROR;
       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));
     m_syntaxParser.InitParser(file.get(), 0);
 
     std::unique_ptr<CPDF_Object, ReleaseDeleter<CPDF_Object>> pTrailer(
         m_syntaxParser.GetObject(nullptr, 0, 0, true));
     if (!pTrailer) {
       m_Pos += m_syntaxParser.SavePos();
       pHints->AddSegment(m_Pos, iTrailerSize);
@@ skipping 634 matching lines @@
   return FormAvailable;
 }
 
 CPDF_DataAvail::PageNode::PageNode() : m_type(PDF_PAGENODE_UNKNOWN) {}
 
 CPDF_DataAvail::PageNode::~PageNode() {
   for (int32_t i = 0; i < m_childNode.GetSize(); ++i)
     delete m_childNode[i];
   m_childNode.RemoveAll();
 }