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

core/fpdfapi/parser/cpdf_parser.cpp

Index: core/fpdfapi/parser/cpdf_parser.cpp
diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index ed20cf73f4f43ce2dd9aa8d12c68486e109ea813..4a6c0169b3c44554b490e322bec701e4d6931dc1 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -598,9 +598,11 @@ bool CPDF_Parser::RebuildCrossRef() {
     bool bOverFlow = false;
     uint32_t size =
         std::min((uint32_t)(m_pSyntax->m_FileLen - pos), kBufferSize);
-    if (!m_pSyntax->m_pFileAccess->ReadBlock(buffer.data(), pos, size))
+    uint32_t readSize =
+        m_pSyntax->m_pFileAccess->ReadBlock(buffer.data(), pos, size);
+    if (readSize != size && !m_pSyntax->m_pFileAccess->IsEOF())
       break;
-
+    size = readSize;
     for (uint32_t i = 0; i < size; i++) {
       uint8_t byte = buffer[i];
       switch (state) {