sd_event_exit, sd_event_get_exit_code — Ask the event loop to exit
#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); |
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.
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.
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.
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.