2 .\" epoll by Davide Libenzi ( efficient event notification retrieval )
3 .\" Copyright (C) 2003 Davide Libenzi
5 .\" This program is free software; you can redistribute it and/or modify
6 .\" it under the terms of the GNU General Public License as published by
7 .\" the Free Software Foundation; either version 2 of the License, or
8 .\" (at your option) any later version.
10 .\" This program is distributed in the hope that it will be useful,
11 .\" but WITHOUT ANY WARRANTY; without even the implied warranty of
12 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 .\" GNU General Public License for more details.
15 .\" You should have received a copy of the GNU General Public License
16 .\" along with this program; if not, write to the Free Software
17 .\" Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 .\" Davide Libenzi <davidel@xmailserver.org>
21 .TH EPOLL_CTL 2 "2002-10-23" Linux "Linux Programmer's Manual"
23 epoll_ctl \- control interface for an epoll descriptor
25 .B #include <sys/epoll.h>
27 .BI "int epoll_ctl(int " epfd ", int " op ", int " fd ", struct epoll_event *" event )
33 by requesting that the operation
35 be performed on the target file descriptor,
39 describes the object linked to the file descriptor
46 typedef union epoll_data {
54 __uint32_t events; /* Epoll events */
55 epoll_data_t data; /* User data variable */
61 member is a bit set composed using the following available event
65 The associated file is available for
70 The associated file is available for
75 Stream socket peer closed connection,
76 or shut down writing half of connection.
77 (This flag is especially useful for writing simple code to detect
78 peer shutdown when using Edge Triggered monitoring.)
81 There is urgent data available for
86 Error condition happened on the associated file descriptor.
88 will always wait for this event; it is not necessary to set it in
92 Hang up happened on the associated file descriptor.
94 will always wait for this event; it is not necessary to set it in
98 Sets the Edge Triggered behaviour for the associated file descriptor.
99 The default behaviour for
101 is Level Triggered. See
103 for more detailed information about Edge and Level Triggered event
104 distribution architectures.
106 .BR EPOLLONESHOT " (since kernel 2.6.2)"
107 Sets the one-shot behaviour for the associated file descriptor.
108 This means that after an event is pulled out with
110 the associated file descriptor is internally disabled and no other events
111 will be reported by the
113 interface. The user must call
117 to re-enable the file descriptor with a new event mask.
121 interface supports all file descriptors that support
129 Add the target file descriptor
135 and associate the event
137 with the internal file linked to
143 associated with the target file descriptor
147 Remove the target file descriptor
155 is ignored and can be NULL (but see BUGS below).
160 returns zero. When an error occurs,
164 is set appropriately.
171 is not a valid file descriptor.
175 was EPOLL_CTL_ADD, and the supplied file descriptor
189 or the requested operation
191 is not supported by this interface.
195 was EPOLL_CTL_MOD or EPOLL_CTL_DEL, and
201 There was insufficient memory to handle the requested
212 is a new API introduced in Linux kernel 2.5.44.
213 The interface should be finalized by Linux kernel 2.5.66.
215 In kernel versions before 2.6.9, the
217 operation required a non-NULL pointer in
219 even though this argument is ignored.
222 can be specified as NULL
226 .BR epoll_create (2),