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153 lines
4.6 KiB
Groff
153 lines
4.6 KiB
Groff
'\" t
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.TH "SD_EVENT_GET_FD" "3" "" "systemd 219" "sd_event_get_fd"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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sd_event_get_fd \- Obtain a file descriptor to poll for event loop events
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.SH "SYNOPSIS"
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.sp
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.ft B
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.nf
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#include <systemd/sd\-bus\&.h>
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.fi
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.ft
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.HP \w'int\ sd_event_get_fd('u
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.BI "int sd_event_get_fd(sd_bus\ *" "event" ");"
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.SH "DESCRIPTION"
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.PP
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\fBsd_event_get_fd()\fR
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returns the file descriptor that the event loop object returned by the
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\fBsd_event_new\fR(3)
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function uses to wait for events\&. This file descriptor can be polled for events\&. This makes it possible to embed the
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\fBsd-event\fR(3)
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event loop inside of another event loop\&.
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.SH "RETURN VALUE"
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.PP
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On success,
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\fBsd_event_get_fd()\fR
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returns a non\-negative integer\&. On failure, it returns a negative errno\-style error code\&.
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.SH "ERRORS"
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.PP
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Returned errors may indicate the following problems:
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.PP
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\fB\-EINVAL\fR
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.RS 4
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\fIevent\fR
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is not a valid pointer to an
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sd_event
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structure\&.
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.RE
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.PP
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\fB\-ECHILD\fR
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.RS 4
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The event loop has been created in a different process\&.
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.RE
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.SH "EXAMPLES"
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.PP
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\fBExample\ \&1.\ \&Integration in glib event loop\fR
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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/***
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Copyright 2014 Tom Gundersen
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation files
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(the "Software"), to deal in the Software without restriction,
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including without limitation the rights to use, copy, modify, merge,
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publish, distribute, sublicense, and/or sell copies of the Software,
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and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software\&.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT\&. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE\&.
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***/
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#include <stdlib\&.h>
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typedef struct SDEventSource {
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GSource source;
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GPollFD pollfd;
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sd_event *event;
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} SDEventSource;
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static gboolean event_prepare(GSource *source, gint *timeout_) {
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return sd_event_prepare(((SDEventSource *)source)\->event) > 0;
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}
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static gboolean event_check(GSource *source) {
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return sd_event_wait(((SDEventSource *)source)\->event, 0) > 0;
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}
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static gboolean event_dispatch(GSource *source, GSourceFunc callback, gpointer user_data) {
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return sd_event_dispatch(((SDEventSource *)source)\->event) > 0;
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}
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static void event_finalize(GSource *source) {
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sd_event_unref(((SDEventSource *)source)\->event);
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}
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static GSourceFuncs event_funcs = {
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\&.prepare = event_prepare,
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\&.check = event_check,
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\&.dispatch = event_dispatch,
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\&.finalize = event_finalize,
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};
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GSource *g_sd_event_create_source(sd_event *event) {
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SDEventSource *source;
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source = (SDEventSource *)g_source_new(&event_funcs, sizeof(SDEventSource));
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source\->event = sd_event_ref(event);
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source\->pollfd\&.fd = sd_event_get_fd(event);
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source\->pollfd\&.events = G_IO_IN | G_IO_HUP | G_IO_ERR;
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g_source_add_poll((GSource *)source, &source\->pollfd);
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return (GSource *)source;
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}
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.fi
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.if n \{\
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.RE
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.\}
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.SH "NOTES"
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.PP
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\fBsd_event_get_fd()\fR
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is available as a shared library, which can be compiled and linked to with the
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\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
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file\&.
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.SH "SEE ALSO"
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.PP
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\fBsd-event\fR(3),
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\fBsd_event_new\fR(3),
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\fBsd_event_ref\fR(3)
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