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     krb5_initlog, krb5_openlog, krb5_closelog, krb5_addlog_dest,
     krb5_addlog_func, krb5_log, krb5_vlog, krb5_log_msg, krb5_vlog_msg -
     Heimdal logging functions


     Kerberos 5 Library (libkrb5, -lkrb5)


     #include <krb5.h>

     typedef void
     (*krb5_log_log_func_t)(const char *time, const char *message,
             void *data);

     typedef void
     (*krb5_log_close_func_t)(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.

     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 doesn’t 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:

                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 FILE:/device.

                Log to the console, this is the same as DEVICE=/dev/console.

                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 LOG_
                (LOG_NOTICE becomes NOTICE).  The default values (as well as
                the values used for unrecognised values), are ERR, and AUTH,
                respectively.  See syslog(3) for a list of priorities and

     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.


                   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.


     syslog(3), krb5.conf(5)


     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 openlog(), and syslog().