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sd_event_source_set_enabled(3) — Linux manual page

SD_EVEN..._ENABLED(3)  sd_event_source_set_enabledSD_EVEN..._ENABLED(3)

NAME        top

       sd_event_source_set_enabled, sd_event_source_get_enabled,       SD_EVENT_ON, SD_EVENT_OFF, SD_EVENT_ONESHOT - Enable or disable       event sources

SYNOPSIS        top

#include <systemd/sd-event.h>enum {SD_EVENT_OFF= 0,SD_EVENT_ON= 1,SD_EVENT_ONESHOT= -1,       };int sd_event_source_set_enabled(sd_event_source *source,intenabled);int sd_event_source_get_enabled(sd_event_source *source,int *ret);

DESCRIPTION        top

sd_event_source_set_enabled()may be used to enable or disable the       event source object specified assource. Theenabled parameter       takes one ofSD_EVENT_ON(to enable),SD_EVENT_OFF(to disable) orSD_EVENT_ONESHOT. If invoked withSD_EVENT_ONESHOTthe event       source will be enabled but automatically reset toSD_EVENT_OFF       after one dispatch. ForSD_EVENT_OFF, the event sourcesource may       beNULL, in which case the function does nothing. Otherwise,source must be a valid pointer to an sd_event_source object.       Event sources that are disabled will not result in event loop       wakeups and will not be dispatched, until they are enabled again.sd_event_source_get_enabled()may be used to query whether the       event source objectsource is currently enabled or not. If both       thesource and the output parameterret areNULL, this function       returns false. Otherwise,source must be a valid pointer to an       sd_event_source object. If the output parameterret is notNULL,       it is set to the enablement state (one ofSD_EVENT_ON,SD_EVENT_OFF,SD_EVENT_ONESHOT). The function also returns true if       the event source is not disabled.       Event source objects are enabled when they are first created with       calls such assd_event_add_io(3),sd_event_add_time(3). However,       depending on the event source type they are enabled continuously       (SD_EVENT_ON) or only for a single invocation of the event source       handler (SD_EVENT_ONESHOT). For details see the respective manual       pages.       As event source objects stay active and may be dispatched as long       as there is at least one reference to them, in many cases it is a       good idea to combine a call tosd_event_source_unref(3) with a       prior call tosd_event_source_set_enabled()withSD_EVENT_OFF, to       ensure the event source is not dispatched again until all other       remaining references are dropped.

RETURN VALUE        top

       On success,sd_event_source_set_enabled()returns a non-negative       integer.sd_event_source_get_enabled()returns zero if the source       is disabled (SD_EVENT_OFF) and a positive integer otherwise. On       failure, they return a negative errno-style error code.Errors       Returned errors may indicate the following problems:-EINVALsource is not a valid pointer to an sd_event_source object.-ENOMEM           Not enough memory.-ECHILD           The event loop has been created in a different process,           library or module instance.

NOTES        top

       Functions described here are available as a shared library, which       can be compiled against and linked to with thelibsystemd pkg-config(1) file.       The code described here usesgetenv(3), which is declared to be       not multi-thread-safe. This means that the code calling the       functions described here must not callsetenv(3) from a parallel       thread. It is recommended to only do calls tosetenv()from an       early phase of the program when no other threads have been       started.

HISTORY        top

sd_event_source_set_enabled()andsd_event_source_get_enabled()       were added in version 229.

SEE ALSO        top

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_unref(3),sd_event_source_set_ratelimit(3)

COLOPHON        top

       This page is part of thesystemd (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 2025-08-11.  (At that       time, the date of the most recent commit that was found in the       repository was 2025-08-11.)  If you discover 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 isnot part of the original manual page), send a mail to       man-pages@man7.orgsystemd 258~rc2SD_EVEN..._ENABLED(3)

Pages that refer to this page:sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_memory_pressure(3), sd_event_add_signal(3), sd_event_add_time(3), sd_event_source_set_prepare(3), sd_event_source_set_ratelimit(3), sd_event_source_unref(3), systemd.directives(7), systemd.index(7)

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