NAME

       sd_event_source_set_description, sd_event_source_get_description - Set or retrieve
       descriptive names of event sources

SYNOPSIS

       #include <systemd/sd-event.h>

       int sd_event_source_set_description(sd_event_source *source, const char *description);

       int sd_event_source_get_description(sd_event_source *source, const char **description);

DESCRIPTION

       sd_event_source_set_description() may be used to set an arbitrary descriptive name for the
       event source object specified as source. This name will be used in debugging messages
       generated by sd-event(3) for this event source, and may be queried using
       sd_event_source_get_description() for debugging purposes. The description parameter shall
       point to a NUL-terminated string or be NULL. In the latter case, the descriptive name will
       be unset. The string is copied internally, hence the description argument is not
       referenced after the function returns.

       sd_event_source_get_description() may be used to query the current descriptive name
       assigned to the event source object source. It returns a pointer to the current name in
       description, stored in memory internal to the event source. The memory is invalidated when
       the event source is destroyed or the descriptive name is changed.

       Event source objects generally have no description set when they are created, except for
       UNIX signal event sources created with sd_event_add_signal(3), whose descriptive name is
       initialized to the signal's C constant name (e.g.  "SIGINT" or "SIGTERM").

RETURN VALUE

       On success, sd_event_source_set_description() and sd_event_source_get_description() return
       a non-negative integer. On failure, they return a negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           source is not a valid pointer to an sd_event_source object or the description argument
           for sd_event_source_get_description() is NULL.

       -ENOMEM
           Not enough memory to copy the name.

       -ECHILD
           The event loop has been created in a different process, library or module instance.

       -ENXIO
           No name was set for the event source.

NOTES

       Functions described here are available as a shared library, which can be compiled against
       and linked to with the libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be not multi-thread-safe.
       This means that the code calling the functions described here must not call setenv(3) from
       a parallel thread. It is recommended to only do calls to setenv() from an early phase of
       the program when no other threads have been started.

HISTORY

       sd_event_source_set_description() and sd_event_source_get_description() were added in
       version 229.

SEE ALSO

       sd-event(3), sd_event_add_io(3), sd_event_add_time(3), sd_event_add_signal(3),
       sd_event_add_child(3), sd_event_add_inotify(3), sd_event_add_defer(3),
       sd_event_source_set_userdata(3)