All GSS-API functions return two types of codes that provide information on the function's success or failure. Both types of status codes are returned as OM_uint32 values. The two types of return codes are as follows:
Major-status codes. These are codes that indicate: a) generic GSS-API routine errors (such as giving a routine an invalid mechanism); b) calling errors specific to a particular GSS-API language binding (namely, a function argument that cannot be read, cannot be written, or is malformed); or c) both. Additionally, major-status codes can provide supplementary information about a routine's status — that an operation is not finished, for example, or that a token has been sent out of order. If no errors occur, the routine returns a major status value of GSS_S_COMPLETE.
Major-status codes are returned as shown here:
OM_uint32 major_status ; /* status returned by GSS-API */ major_status = gss_generic_function(arg1, arg2 ...);
OM_uint32 maj_stat; maj_sta = gss_generic_function(arg1, arg2 ...); if (maj_stat == GSS_CREDENTIALS_EXPIRED) <do something...>
Minor status codes. These are returned by the underlying mechanism, and so are not specifically documented in this manual.
Every GSS-API function has as its first argument an OM_uint32 for the minor code status. The minor status code is stored here when the function returns to the function that called it:
OM_uint32 *minor_status ; /* status returned by mech */ major_status = gss_generic_function(&minor_status, arg1, arg2 ...);
The minor_status parameter is always set by a GSS-API routine, even if it returns a fatal major-code error, although most other output parameters can remain unset. However, output parameters that are expected to return pointers to storage allocated by the routine are set to NULL to indicate that no storage was actually allocated. Any length field associated with such pointers (as in a gss_buffer_desc structure) are set to zero. In these cases applications don't need to release these buffers.