Computes the checksum of the specified image file.

Syntax

PIMAGE_NT_HEADERS CheckSumMappedFile(
  __in   PVOID BaseAddress,
  __in   DWORD FileLength,
  __out  PDWORD HeaderSum,
  __out  PDWORD CheckSum
);

Parameters

BaseAddress [in]

The base address of the mapped file. This value is obtained by calling the MapViewOfFile function.

FileLength [in]

The size of the file, in bytes.

HeaderSum [out]

A pointer to a variable that receives the original checksum from the image file, or zero if there is an error.

CheckSum [out]

A pointer to the variable that receives the computed checksum.

Return Value

If the function succeeds, the return value is a pointer to the IMAGE_NT_HEADERS structure contained in the mapped image.

If the function fails, the return value is NULL. To retrieve extended error information, call GetLastError.

Remarks

The CheckSumMappedFile 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 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.

All ImageHlp functions, such as this one, are single threaded. Therefore, calls from more than one thread to this function will likely result in unexpected behavior or memory corruption. To avoid this, you must synchronize all concurrent calls from more than one thread to this function.

Requirements

See Also

ImageHlp Functions

IMAGE_NT_HEADERS

MapFileAndCheckSum

MapViewOfFile

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Build date: 1/22/2010