pfnIsFileSupported callback function

The pfnIsFileSupported callback function queries the subject interface packages (SIPs) listed in the registry to determine which SIP handles the file type.


pfnIsFileSupported Pfnisfilesupported;

BOOL Pfnisfilesupported(
  IN HANDLE hFile,
  OUT GUID *pgSubject



A handle to the file.


The GUID that identifies the SIP that handles the file type.

Return Value

If the function succeeds, the function returns TRUE.

If the function fails, it returns FALSE. For extended error information, call GetLastError.


If the SIP supports the file type passed by hfile, the function returns TRUE, and sets pgSubject to the GUID that identifies the SIP for handling the file type.

Each SIP implements its own version of the function that determines whether the file type is supported. The specific name of the function may vary depending on the implementation of the SIP, but the signature of the function will match that of the pfnIsFileSupported function. The function name is added to the registry by the CryptSIPAddProvider function, which takes the function name as a parameter in the pwszIsFunctionName field of the SIP_ADD_NEWPROVIDER structure.


Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header mssip.h