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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |COLOPHON | |
SD_EVE...LLBACK(3) sd_event_source_set_destroy_callbackSD_EVE...LLBACK(3)sd_event_source_set_destroy_callback, sd_event_source_get_destroy_callback, sd_event_destroy_t - Define the callback function for resource cleanup
#include <systemd/sd-event.h>typedef int (*sd_event_destroy_t)(void *userdata);int sd_event_source_set_destroy_callback(sd_event_source *source,sd_event_destroy_tcallback);int sd_event_source_get_destroy_callback(sd_event_source *source,sd_event_destroy_t *callback);
sd_event_source_set_destroy_callback()setscallback as the callback function to be called right before the event source objectsource is deallocated. Theuserdata pointer from the event source object will be passed as theuserdata parameter. This pointer can be set by an argument to the constructor functions, seesd_event_add_io(3), or directly, seesd_event_source_set_userdata(3). This callback function is called even ifuserdata isNULL. Note that this callback is invoked at a time where the event source object itself is already invalidated, and executing operations or taking new references to the event source object is not permissible.sd_event_source_get_destroy_callback()returns the current callback forsource in thecallback parameter.
On success,sd_event_source_set_destroy_callback()returns 0 or a positive integer. On failure, it returns a negative errno-style error code.sd_event_source_get_destroy_callback()returns positive if the destroy callback function is set, 0 if not. On failure, returns a negative errno-style error code.Errors Returned errors may indicate the following problems:-EINVAL Thesource parameter isNULL.
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.
sd_event_destroy_t(),sd_event_source_set_destroy_callback(), andsd_event_source_get_destroy_callback()were added in version 239.
systemd(1),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_set_userdata(3)
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_EVE...LLBACK(3)Pages that refer to this page:systemd.directives(7), systemd.index(7)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |