Ubuntu Manpage: sd_event_exit, sd_event_get_exit_code

Provided by: libsystemd-dev_256.5-2ubuntu3.1_amd64

NAME

       sd_event_exit, sd_event_get_exit_code - Ask the event loop to exit

SYNOPSIS

       #include <systemd/sd-event.h>

       int sd_event_exit(sd_event *event, int code);

       int sd_event_get_exit_code(sd_event *event, int *code);

DESCRIPTION

sd_event_exit() requests the event loop specified in the event event loop object to exit.
The code parameter may be any integer value and is returned as-is by sd_event_loop(3)
after the last event loop iteration. It may also be queried using
sd_event_get_exit_code(), see below.

When exiting is requested the event loop will stop listening for and dispatching regular
event sources. Instead it will proceed with executing only event sources registered with
sd_event_add_exit(3) in the order defined by their priority. After all exit event sources
have been dispatched the event loop is terminated.

If sd_event_exit() is invoked a second time while the event loop is still processing exit
event sources, the exit code stored in the event loop object is updated, but otherwise no
further operation is executed.

sd_event_get_exit_code() may be used to query the exit code passed to an earlier call of
sd_event_exit(). The return parameter code may be set to NULL, in order to simply check if
sd_event_exit() has been called before (as sd_event_get_exit_code() fails with -ENODATA if
that's not the case, see below).

While the full positive and negative integer ranges may be used for the exit code, care
should be taken not pick exit codes that conflict with regular exit codes returned by
sd_event_loop(), if these exit codes shall be distinguishable.

Note that for most event source types passing the callback pointer as NULL in the
respective constructor call (i.e. in sd_event_add_time(3), sd_event_add_signal(3), ...)
has the effect of sd_event_exit() being invoked once the event source triggers, with the
specified userdata pointer cast to an integer as the exit code parameter. This is useful
to automatically terminate an event loop after some condition, such as a time-out or
reception of SIGTERM or similar. See the documentation for the respective constructor call
for details.

RETURN VALUE

       On success, sd_event_exit() and sd_event_get_exit_code() return 0 or a positive integer.
       On failure, they return a negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           The event loop object or error code pointer are invalid.

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

       -ESTALE
           The event loop has exited already and all exit handlers are already processed.

       -ENODATA
           Returned by sd_event_get_exit_code() in case the event loop has not been requested to
           exit yet.

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