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

fpdfsdk/fsdk_define.h

Index: fpdfsdk/fsdk_define.h
diff --git a/fpdfsdk/fsdk_define.h b/fpdfsdk/fsdk_define.h
index 3a75c8450078275c3a4359ba4ed6fdfaab50f874..fbde3ee008bab7c0bcd413cf24c9a5eabe2f5e00 100644
--- a/fpdfsdk/fsdk_define.h
+++ b/fpdfsdk/fsdk_define.h
@@ -33,10 +33,12 @@ class CPDF_CustomAccess final : public IFX_SeekableReadStream {
   // IFX_SeekableReadStream
   FX_FILESIZE GetSize() override;
   void Release() override;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+  bool IsEOF() override;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
 
  private:
   FPDF_FILEACCESS m_FileAccess;
+  FX_FILESIZE m_nCurPos;
 };
 
 #ifdef PDF_ENABLE_XFA
@@ -51,7 +53,7 @@ class CFPDF_FileStream : public IFX_SeekableStream {
   FX_FILESIZE GetSize() override;
   bool IsEOF() override;
   FX_FILESIZE GetPosition() override;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
   size_t ReadBlock(void* buffer, size_t size) override;
   bool WriteBlock(const void* buffer, FX_FILESIZE offset, size_t size) override;
   bool Flush() override;