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.
Destinations
The defined destinations (as specified in
krb5.conf) follows:
STDERR
This logs to the program's stderr.
FILE=/file
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.
DEVICE=/device
This logs to the specified device, at present this is the same as FILE:/device.
CONSOLE
Log to the console, this is the same as DEVICE=/dev/console.
SYSLOG[:priority[:facility]]
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 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.