These functions logs messages to one or more destinations.
The krb5_openlog function creates a logging facility, that is used to log messages. A facility consists of one or more destinations (which can be files or syslog or some other device). The program parameter should be the generic name of the program that is doing the logging. This name is used to lookup which destinations to use. This information is contained in the logging section of the krb5.conf configuration file. If no entry is found for program, the entry for default is used, or if that is missing too, SYSLOG will be used as destination.
To close a logging facility, use the krb5_closelog function.
To log a message to a facility use one of the functions krb5_log, krb5_log_msg, krb5_vlog, or krb5_vlog_msg. The functions ending in _msg return in reply a pointer to the message that just got logged. This string is allocated, and should be freed with free. The format is a standard printf style format string (but see the BUGS section).
If you want better control of where things gets logged, you can instead of using krb5_openlog call krb5_initlog, which just initializes a facility, but doesnt define any actual logging destinations. You can then add destinations with the krb5_addlog_dest and krb5_addlog_func functions. The first of these takes a string specifying a logging destination, and adds this to the facility. If you want to do some non-standard logging you can use the krb5_addlog_func function, which takes a function to use when logging. The log function is called for each message with time being a string specifying the current time, and message the message to log. close is called when the facility is closed. You can pass application specific data in the data parameter. The min and max parameter are the same as in a destination (defined below). To specify a max of infinity, pass -1.
krb5_openlog calls krb5_initlog and then calls krb5_addlog_dest for each destination found.
The defined destinations (as specified in krb5.conf) follows: