SD_EVENT_ADD_SIGNAL(3)        sd_event_add_signal       SD_EVENT_ADD_SIGNAL(3)

NAME
       sd_event_add_signal, sd_event_source_get_signal,
       sd_event_signal_handler_t, SD_EVENT_SIGNAL_PROCMASK - Add a UNIX
       process signal event source to an event loop

SYNOPSIS
       #include <systemd/sd-event.h>

       typedef struct sd_event_source sd_event_source;

       SD_EVENT_SIGNAL_PROCMASK

       typedef int (*sd_event_signal_handler_t)(sd_event_source *s,
                                                const struct signalfd_siginfo *si,
                                                void *userdata);

       int sd_event_add_signal(sd_event *event, sd_event_source **source,
                               int signal, sd_event_signal_handler_t handler,
                               void *userdata);

       int sd_event_source_get_signal(sd_event_source *source);

DESCRIPTION
       sd_event_add_signal() adds a new UNIX process signal event source to an
       event loop. The event loop object is specified in the event parameter,
       and the event source object is returned in the source parameter. The
       signal parameter specifies the numeric signal to be handled (see
       signal(7)).

       The handler parameter is a function to call when the signal is received
       or NULL. The handler function will be passed the userdata pointer,
       which may be chosen freely by the caller. The handler also receives a
       pointer to a signalfd_siginfo structure containing information about
       the received signal. See signalfd(2) for further information. The
       handler may return negative to signal an error (see below), other
       return values are ignored. If handler is NULL, a default handler that
       calls sd_event_exit(3) will be used.

       Only a single handler may be installed for a specific signal. The
       signal must be blocked in all threads before this function is called
       (using sigprocmask(2) or pthread_sigmask(3)). For convenience, if the
       special flag SD_EVENT_SIGNAL_PROCMASK is ORed into the specified signal
       the signal will be automatically masked as necessary, for the calling
       thread. Note that this only works reliably if the signal is already
       masked in all other threads of the process, or if there are no other
       threads at the moment of invocation.

       By default, the event source is enabled permanently (SD_EVENT_ON), but
       this may be changed with sd_event_source_set_enabled(3). If the handler
       function returns a negative error code, it will either be disabled
       after the invocation, even if the SD_EVENT_ON mode was requested
       before, or it will cause the loop to terminate, see
       sd_event_source_set_exit_on_failure(3).

       To destroy an event source object use sd_event_source_unref(3), but
       note that the event source is only removed from the event loop when all
       references to the event source are dropped. To make sure an event
       source does not fire anymore, even if it is still referenced, disable
       the event source using sd_event_source_set_enabled(3) with
       SD_EVENT_OFF.

       If the second parameter of sd_event_add_signal() is NULL no reference
       to the event source object is returned. In this case the event source
       is considered "floating", and will be destroyed implicitly when the
       event loop itself is destroyed.

       If the handler parameter to sd_event_add_signal() is NULL, and the
       event source fires, this will be considered a request to exit the event
       loop. In this case, the userdata parameter, cast to an integer, is
       passed as the exit code parameter to sd_event_exit(3).

       sd_event_source_get_signal() returns the configured signal number of an
       event source created previously with sd_event_add_signal(). It takes
       the event source object as the source parameter.

RETURN VALUE
       On success, these functions return 0 or a positive integer. On failure,
       they return a negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -ENOMEM
           Not enough memory to allocate an object.

       -EINVAL
           An invalid argument has been passed.

       -EBUSY
           A handler is already installed for this signal or the signal was
           not blocked previously.

       -ESTALE
           The event loop is already terminated.

       -ECHILD
           The event loop has been created in a different process.

       -EDOM
           The passed event source is not a signal event source.

NOTES
       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO
       systemd(1), sd-event(3), sd_event_new(3), sd_event_now(3),
       sd_event_add_io(3), sd_event_add_time(3), sd_event_add_child(3),
       sd_event_add_inotify(3), sd_event_add_defer(3),
       sd_event_source_set_enabled(3), sd_event_source_set_description(3),
       sd_event_source_set_userdata(3), sd_event_source_set_floating(3),
       signal(7), signalfd(2), sigprocmask(2), pthread_sigmask(3)

systemd 252                                             SD_EVENT_ADD_SIGNAL(3)

Czas wygenerowania: 0.00045 sek.

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