|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON |
SD_EVENT_SOURCE_SET_PREPARE(3)ent_source_set_prepareNT_SOURCE_SET_PREPARE(3)
sd_event_source_set_prepare - Set a preparation callback for event
sources
#include <systemd/sd-event.h>
int sd_event_source_set_prepare(sd_event_source *source,
sd_event_handler_t callback);
typedef int (*sd_event_handler_t)(sd_event_source *s,
void *userdata);
sd_event_source_set_prepare() may be used to set a preparation
callback for the event source object specified as source. The
callback function specified as callback will be invoked immediately
before the event loop goes to sleep to wait for incoming events. It
is invoked with the user data pointer passed when the event source
was created. The event source will be disabled if the callback
function returns a negative error code. The callback function may be
used to reconfigure the precise events to wait for. If the callback
parameter is passed as NULL the callback function is reset.
Event source objects have no preparation callback associated when
they are first created with calls such as sd_event_add_io(3),
sd_event_add_time(3). Preparation callback functions are supported
for all event source types with the exception of those created with
sd_event_add_exit(3). Preparation callback functions are dispatched
in the order indicated by the event source's priority field, as set
with sd_event_source_set_priority(3). Preparation callbacks of
disabled event sources (see sd_event_source_set_enabled(3)) are not
invoked.
On success, sd_event_source_set_prepare() returns a non-negative
integer. On failure, it returns a negative errno-style error code.
Returned errors may indicate the following problems:
-EINVAL
source is not a valid pointer to an sd_event_source object.
-ESTALE
The event loop is already terminated.
-ENOMEM
Not enough memory.
-ECHILD
The event loop has been created in a different process.
-EDOM
The specified event source has been created with
sd_event_add_exit(3).
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
sd_event_add_child(3), sd_event_add_signal(3), sd_event_add_defer(3),
sd_event_source_set_enabled(3), sd_event_source_set_priority(3),
sd_event_source_set_userdata(3)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
systemd 234 SD_EVENT_SOURCE_SET_PREPARE(3)
Pages that refer to this page: sd-event(3), sd_event_wait(3), systemd.directives(7), systemd.index(7)