1SD_EVENT_SOURCE_SET_DEsSdT_ReOvYe_nCtA_LsLoBuArCcKe(_3s)etS_Dd_eEsVtErNoTy__ScOaUlRlCbEa_cSkET_DESTROY_CALLBACK(3)
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NAME

6       sd_event_source_set_destroy_callback,
7       sd_event_source_get_destroy_callback, sd_event_destroy_t - Define the
8       callback function for resource cleanup
9

SYNOPSIS

11       #include <systemd/sd-event.h>
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13       typedef int (*sd_event_destroy_t)(void *userdata);
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15       int sd_event_source_set_destroy_callback(sd_event_source *source,
16                                                sd_event_destroy_t callback);
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18       int sd_event_source_get_destroy_callback(sd_event_source *source,
19                                                sd_event_destroy_t *callback);
20

DESCRIPTION

22       sd_event_source_set_destroy_callback() sets callback as the callback
23       function to be called right before the event source object source is
24       deallocated. The userdata pointer from the event source object will be
25       passed as the userdata parameter. This pointer can be set by an
26       argument to the constructor functions, see sd_event_add_io(3), or
27       directly, see sd_event_source_set_userdata(3). This callback function
28       is called even if userdata is NULL. Note that this callback is invoked
29       at a time where the event source object itself is already invalidated,
30       and executing operations or taking new references to the event source
31       object is not permissible.
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33       sd_event_source_get_destroy_callback() returns the current callback for
34       source in the callback parameter.
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RETURN VALUE

37       On success, sd_event_source_set_destroy_callback() returns 0 or a
38       positive integer. On failure, it returns a negative errno-style error
39       code.
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41       sd_event_source_get_destroy_callback() returns positive if the destroy
42       callback function is set, 0 if not. On failure, returns a negative
43       errno-style error code.
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45   Errors
46       Returned errors may indicate the following problems:
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48       -EINVAL
49           The source parameter is NULL.
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NOTES

52       Functions described here are available as a shared library, which can
53       be compiled against and linked to with the libsystemd pkg-config(1)
54       file.
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56       The code described here uses getenv(3), which is declared to be not
57       multi-thread-safe. This means that the code calling the functions
58       described here must not call setenv(3) from a parallel thread. It is
59       recommended to only do calls to setenv() from an early phase of the
60       program when no other threads have been started.
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SEE ALSO

63       systemd(1), sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
64       sd_event_add_signal(3), sd_event_add_child(3), sd_event_add_inotify(3),
65       sd_event_add_defer(3), sd_event_source_set_userdata(3)
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69systemd 254                            SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)
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