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

xfa/fde/xml/cfx_saxreader.cpp

Index: xfa/fde/xml/cfx_saxreader.cpp
diff --git a/xfa/fde/xml/cfx_saxreader.cpp b/xfa/fde/xml/cfx_saxreader.cpp
index ec22c735416f8eacbb293b8ce58477639c275e75..b616516490de2837be80a4cd4797ddd2ba1ba289 100644
--- a/xfa/fde/xml/cfx_saxreader.cpp
+++ b/xfa/fde/xml/cfx_saxreader.cpp
@@ -84,7 +84,8 @@ FX_BOOL CFX_SAXFile::StartFile(IFX_FileRead* pFile,
   }
   m_dwBufSize = std::min(dwLen, kSaxFileBufSize);
   m_pBuf = FX_Alloc(uint8_t, m_dwBufSize);
-  if (!pFile->ReadBlock(m_pBuf, dwStart, m_dwBufSize)) {
+  if (pFile->ReadBlock(m_pBuf, dwStart, m_dwBufSize) != m_dwBufSize &&
+      !pFile->IsEOF()) {
     return FALSE;
   }
   m_dwStart = dwStart;
@@ -101,7 +102,8 @@ FX_BOOL CFX_SAXFile::ReadNextBlock() {
     return FALSE;
   }
   m_dwBufSize = std::min(dwSize, kSaxFileBufSize);
-  if (!m_pFile->ReadBlock(m_pBuf, m_dwCur, m_dwBufSize)) {
+  if (m_pFile->ReadBlock(m_pBuf, m_dwCur, m_dwBufSize) != m_dwBufSize &&
+      !m_pFile->IsEOF()) {
     return FALSE;
   }
   m_dwBufIndex = 0;