MapFileAndCheckSum

The MapFileAndCheckSum function computes the checksum of the specified file.

ULONG MapFileAndCheckSum(
  IN LPTSTR Filename,      
  OUT LPDWORD HeaderSum,  
  OUT LPDWORD CheckSum    
);

Parameters

Filename
Pointer to a null-terminated string that specifies the filename of the file for which the checksum is to be computed.
HeaderSum
Pointer to a variable that receives the original checksum from the image file, or zero if there is an error.
CheckSum
Pointer to the variable that receives the computed checksum.

Return Values

If the function succeeds, the return value is CHECKSUM_SUCCESS.

If the function fails, the return value is one of the following:

Value Meaning
CHECKSUM_OPEN_FAILURE Could not open the file.
CHECKSUM_MAP_FAILURE Could not create the file mapping for the file.
CHECKSUM_MAPVIEW_FAILURE Could not map a view of the file.
CHECKSUM_UNICODE_FAILURE Could not convert the filename to UNICODE.

Remarks

The MapFileAndCheckSum function computes a new checksum for the file and returns it in the CheckSum parameter. This function is used by any application that creates or modifies an executable image. Checksums are required for Windows NT kernel mode drivers and some system DLLs. The linker computes the original checksum at link time, if you use the appropriate linker switch. For more details, see your linker documentation.

It is recommended that all images have valid checksums. It is the caller's responsibility to place the newly computed checksum into the mapped image and update the on-disk image of the file.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Windows CE: Unsupported.
  Header: Declared in imagehlp.h.
  Import Library: Use imagehlp.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also

PE Image Helper (ImageHlp) Overview, ImageHlp Image Modification Functions, CheckSumMappedFile