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

core/fpdfapi/parser/fpdf_parser_utility.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/fpdfapi/parser/fpdf_parser_utility.h"
 
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
@@ skipping 54 matching lines @@
     'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
     'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
     'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
     'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R', 'R',
     'R', 'R', 'R', 'R', 'R', 'R', 'R', 'W'};
 
 int32_t GetHeaderOffset(IFX_SeekableReadStream* pFile) {
   const size_t kBufSize = 4;
   uint8_t buf[kBufSize];
   for (int32_t offset = 0; offset <= 1024; ++offset) {
-    if (!pFile->ReadBlock(buf, offset, kBufSize))
+    if (pFile->ReadBlock(buf, offset, kBufSize) != kBufSize && !pFile->IsEOF())
       return -1;
 
     if (memcmp(buf, "%PDF", 4) == 0)

[Tom Sepez, 2016/11/14 20:27:40]

might not have read 4 bytes if EOF.

       return offset;
   }
   return -1;
 }
 
 int32_t GetDirectInteger(CPDF_Dictionary* pDict, const CFX_ByteString& key) {
   CPDF_Number* pObj = ToNumber(pDict->GetObjectFor(key));
   return pObj ? pObj->GetInteger() : 0;
 }
 
@@ skipping 123 matching lines @@
       buf.AppendBlock(acc.GetData(), acc.GetSize());
       buf << "\r\nendstream";
       break;
     }
     default:
       ASSERT(false);
       break;
   }
   return buf;
 }