man/sd_event_add_defer.3

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   2 .TH "SD_EVENT_ADD_DEFER" "3" "" "systemd 217" "sd_event_add_defer"
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   8 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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  22 .SH "NAME"
  23 sd_event_add_defer, sd_event_add_post, sd_event_add_exit \- Add static event sources to an event loop
  24 .SH "SYNOPSIS"
  25 .sp
  26 .ft B
  27 .nf
  28 #include <systemd/sd\-bus\&.h>
  29 .fi
  30 .ft
  31 .HP \w'int\ sd_event_add_defer('u
  32 .BI "int sd_event_add_defer(sd_event\ *" "event" ", sd_event_source\ **" "source" ", sd_event_handler_t\ " "handler" ", void\ *" "userdata" ");"
  33 .HP \w'int\ sd_event_add_post('u
  34 .BI "int sd_event_add_post(sd_event\ *" "event" ", sd_event_source\ **" "source" ", sd_event_handler_t\ " "handler" ", void\ *" "userdata" ");"
  35 .HP \w'int\ sd_event_add_exit('u
  36 .BI "int sd_event_add_exit(sd_event\ *" "event" ", sd_event_source\ **" "source" ", sd_event_handler_t\ " "handler" ", void\ *" "userdata" ");"
  37 .HP \w'typedef\ int\ (*sd_event_handler_t)('u
  38 .BI "typedef int (*sd_event_handler_t)(sd_event_source\ *" "s" ", void\ *" "userdata" ");"
  39 .SH "DESCRIPTION"
  40 .PP
  41 Those three functions add new event sources to an event loop object\&. The event loop is specified in
  42 \fIevent\fR, the event source is returned in the
  43 \fIsource\fR
  44 parameter\&. The event sources are enabled statically and will "fire" when the event loop is run and the conditions described below are met\&. The handler function will be passed the
  45 \fIuserdata\fR
  46 pointer, which may be chosen freely by the caller\&.
  47 .PP
  48 \fBsd_event_add_defer()\fR
  49 adds a new event source that will "fire" the next time the event loop is run\&. By default, the handler will be called once (\fBSD_EVENT_ONESHOT\fR)\&.
  50 .PP
  51 \fBsd_event_add_defer()\fR
  52 adds a new event source that will "fire" if any event handlers are invoked whenever the event loop is run\&. By default, the source is enabled permanently (\fBSD_EVENT_ON\fR)\&.
  53 .PP
  54 \fBsd_event_add_exit()\fR
  55 adds a new event source that will "fire" when the event loop is terminated with
  56 \fBsd_event_exit()\fR\&.
  57 .PP
  58 The
  59 \fBsd_event_source_set_enabled\fR(3)
  60 function may be used to enable the event source permanently (\fBSD_EVENT_ON\fR) or to make it fire just once (\fBSD_EVENT_ONESHOT\fR)\&. If the handler function returns a negative error code, it will be disabled after the invocation, even if
  61 \fBSD_EVENT_ON\fR
  62 mode is set\&.
  63 .SH "RETURN VALUE"
  64 .PP
  65 On success, this functions return 0 or a positive integer\&. On failure, they return a negative errno\-style error code\&.
  66 .SH "ERRORS"
  67 .PP
  68 Returned errors may indicate the following problems:
  69 .PP
  70 \fB\-ENOMEM\fR
  71 .RS 4
  72 Not enough memory to allocate an object\&.
  73 .RE
  74 .PP
  75 \fB\-EINVAL\fR
  76 .RS 4
  77 An invalid argument has been passed\&.
  78 .RE
  79 .PP
  80 \fB\-ESTALE\fR
  81 .RS 4
  82 The event loop is already terminated\&.
  83 .RE
  84 .PP
  85 \fB\-ECHILD\fR
  86 .RS 4
  87 The event loop has been created in a different process\&.
  88 .RE
  89 .SH "NOTES"
  90 .PP
  91 Functions described here are available as a shared library, which can be compiled and linked to with the
  92 \fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
  93 file\&.
  94 .SH "SEE ALSO"
  95 .PP
  96 \fBsystemd\fR(1),
  97 \fBsd-event\fR(3),
  98 \fBsd_event_new\fR(3),
  99 \fBsd_event_add_time\fR(3),
 100 \fBsd_event_add_signal\fR(3),
 101 \fBsd_event_add_child\fR(3),
 102 \fBsd_event_source_set_enabled\fR(3)