These functions prints a warning message to some destination. format is a printf style format specifying the message to print. The forms not ending in an "x" prints the error string associated with code along with the message. The "err" functions exits with exit status eval after printing the message.
The krb5_set_warn_func function sets the destination for warning messages to the specified facility. Messages logged with the "warn" functions have a log level of 1, while the "err" functions logs with level 0.
krb5_get_err_text fetches the human readable strings describing the error-code.