Kerberos 5 Library (libkrb5, -lkrb5)
(*krb5_log_log_func_t)(const char *time, const char *message, void *data);
krb5_addlog_dest(krb5_context context, krb5_log_facility *facility, const char *destination);
krb5_addlog_func(krb5_context context, krb5_log_facility *facility, int min, int max, krb5_log_log_func_t log, krb5_log_close_func_t close, void *data);
krb5_closelog(krb5_context context, krb5_log_facility *facility);
krb5_initlog(krb5_context context, const char *program, krb5_log_facility **facility);
krb5_log(krb5_context context, krb5_log_facility *facility, int level, const char *format, ...);
krb5_log_msg(krb5_context context, krb5_log_facility *facility, char **reply, int level, const char *format, ...);
krb5_openlog(krb5_context context, const char *program, krb5_log_facility **facility);
krb5_vlog(krb5_context context, krb5_log_facility *facility, int level, const char *format, va_list arglist);
krb5_vlog_msg(krb5_context context, krb5_log_facility *facility, char **reply, int level, const char *format, va_list arglist);
These functions logs messages to one or more destinations.
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
To log a message to a facility use one of the functions
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_initlog(), which just initializes a facility, but doesn't define any actual logging destinations. You can then add destinations with the
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_initlog() and then calls
krb5_addlog_dest() for each destination found.
The defined destinations (as specified in
This logs to the program's stderr.
Log to the specified file. The form using a colon appends to the file, the form with an equal truncates the file. The truncating form keeps the file open, while the appending form closes it after each log message (which makes it possible to rotate logs). The truncating form is mainly for compatibility with the MIT libkrb5.
This logs to the specified device, at present this is the same as
Log to the console, this is the same as
Send messages to the syslog system, using priority, and facility. To get the name for one of these, you take the name of the macro passed to syslog(3), and remove the leading
NOTICE). The default values (as well as the values used for unrecognised values), are
AUTH, respectively. See syslog(3) for a list of priorities and facilities.
Each destination may optionally be prepended with a range of logging levels, specified as
min-max/. If the level parameter to
krb5_log() is within this range (inclusive) the message gets logged to this destination, otherwise not. Either of the min and max valued may be omitted, in this case min is assumed to be zero, and max is assumed to be infinity. If you don't include a dash, both min and max gets set to the specified value. If no range is specified, all messages gets logged.
[logging] kdc = 0/FILE:/var/log/kdc.log kdc = 1-/SYSLOG:INFO:USER default = STDERR
This will log all messages from the kdc program with level 0 to
/var/log/kdc.log, other messages will be logged to syslog with priority
LOG_INFO, and facility
LOG_USER. All other programs will log all messages to their stderr.
These functions use
asprintf() to format the message. If your operating system does not have a working
asprintf(), a replacement will be used. At present this replacement does not handle some correct conversion specifications (like floating point numbers). Until this is fixed, the use of these conversions should be avoided.
If logging is done to the syslog facility, these functions might not be thread-safe, depending on the implementation of
heimdal-krb5.conf(5), kdc(8), kgetcred(1).
The man pages krb5_addlog_dest(3), krb5_addlog_func(3), krb5_closelog(3), krb5_log(3), krb5_log_msg(3), krb5_openlog(3), krb5_vlog(3) and krb5_vlog_msg(3) are aliases of krb5_initlog(3).