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

core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
index a29137cd4315a8c185709be10ce1dcd34aed168f..abb4698f0d1ba2766cccb86c714c98df01731c1c 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
@@ -77,7 +77,9 @@ FX_BOOL CPDF_SyntaxParser::GetNextChar(uint8_t& ch) {
       }
     }
 
-    if (!m_pFileAccess->ReadBlock(m_pFileBuf, read_pos, read_size))
+    if (m_pFileAccess->ReadBlock(m_pFileBuf, read_pos, read_size) !=
+            read_size &&
+        !m_pFileAccess->IsEOF())
       return FALSE;
 
     m_BufOffset = read_pos;
@@ -109,7 +111,9 @@ FX_BOOL CPDF_SyntaxParser::GetCharAtBackward(FX_FILESIZE pos, uint8_t& ch) {
       }
     }
 
-    if (!m_pFileAccess->ReadBlock(m_pFileBuf, read_pos, read_size))
+    if (m_pFileAccess->ReadBlock(m_pFileBuf, read_pos, read_size) !=
+            read_size &&
+        !m_pFileAccess->IsEOF())
       return FALSE;
 
     m_BufOffset = read_pos;
@@ -119,7 +123,8 @@ FX_BOOL CPDF_SyntaxParser::GetCharAtBackward(FX_FILESIZE pos, uint8_t& ch) {
 }
 
 FX_BOOL CPDF_SyntaxParser::ReadBlock(uint8_t* pBuf, uint32_t size) {
-  if (!m_pFileAccess->ReadBlock(pBuf, m_Pos + m_HeaderOffset, size))
+  if (m_pFileAccess->ReadBlock(pBuf, m_Pos + m_HeaderOffset, size) != size &&
+      !m_pFileAccess->IsEOF())
     return FALSE;
   m_Pos += size;
   return TRUE;