.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (C) 1997 Andries Brouwer (aeb@cwi.nl)
.\" and Copyright (C) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Additions from Richard Gooch <rgooch@atnf.CSIRO.AU> and aeb, 971207
.\" 2006-03-13, mtk, Added ppoll() + various other rewordings
.\" 2006-07-01, mtk, Added POLLRDHUP + various other wording and
.\"	formatting changes.
.\"
.\" FIXME . 2.6.17 has a definition for POLLREMOVE, but this
.\" flag is not used in the code.  Check later to see if it
.\" does get a use.  2.6.21 still shows no use.
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-12-11, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated & Modified 2004-05-22, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated & Modified 2005-01-03, Yuichi SATO
.\" Updated & Modified 2005-10-10, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2005-12-05, Akihiro MOTOKI, Catch up to LDP man-pages 2.16
.\" Updated 2006-04-16, Akihiro MOTOKI, Catch up to LDP man-pages 2.28
.\" Updated 2006-07-23, Akihiro MOTOKI, Catch up to LDP man-pages 2.36
.\"
.\"WORD:	descriptor		ǥץ
.\"
.TH POLL 2 2006-03-13 "Linux" "Linux Programmer's Manual"
.SH ̾
poll, ppoll \- եǥץˤ륤٥ȤԤ
.SH 
.nf
.B #include <poll.h>
.sp
.BI "int poll(struct pollfd *" fds ", nfds_t " nfds ", int " timeout );
.sp
.B #define _GNU_SOURCE
.B #include <poll.h>
.sp
.BI "int ppoll(struct pollfd *" fds ", nfds_t " nfds ", "
.BI "        const struct timespec *" timeout ", const sigset_t *" sigmask );
.fi
.SH 
.BR poll ()

.BR select (2)
ƱͤλŻԤĤޤꡢեǥץΤ줫Ĥ
I/O ¹Բǽʾ֤ˤʤΤԤġ

ƻ뤹եǥץϡ
.I fds
ǻꤹ롣
.I fds
ϡʲηι¤Τ
.I nfds
ĤǤ롣
.in +4n
.nf

struct pollfd {
    int   fd;         /* file descriptor */
    short events;     /* requested events */
    short revents;    /* returned events */
};

.fi
.in
¤Τ
.I fd
ˤϥץ󤷤եΥեǥץ롣

¤Τ
.I events
Ǥϥѥ᡼ǡץꥱ󤬶̣äƤ륤٥Ȥ
ӥåȥޥꤹ롣

.I revents
ǤϽϥѥ᡼ǡºݤ˵ä٥Ȥͥˤꤵ롣
.I revents
֤ӥåˤϡ
.I events
ǻꤷΤΤɤ줫⤷
.BR POLLERR ,
.BR POLLHUP ,
.B POLLNVAL
ΤΰĤޤޤ
.RB ( POLLERR ,
.BR POLLHUP ,
.B POLLNVAL
 3ĤΥӥåȤ
.I events
˻ꤷƤ̣ʤб֤ξ
.I revents
ꤵ)

ɤΥեǥץˤ׵ᤷ٥ȤȯƤ餺
顼ⵯʤ硢
.BR poll ()
ϥ٥ȤΤ줫Ĥȯޤ (block) 롣

.I timeout

.BR poll ()
ߤ֤ξ¤ꤹΤǡߥñ̤ǻꤹ롣
.I timeout
ͤꤹȡॢȻ̵֤¤Ȥʤ롣

.I events
˻ꤷꡢ
.I revents
֤ӥåȤ \fI<poll.h>\fP Ƥ:
.RS
.TP
.B POLLIN
ɤ߽Фǽʥǡ롣
.TP
.B POLLPRI
ɤ߽Фǽʶ۵ޥǡ (urgent data) 
(㤨СTCP åȤӰ賰 (out-of-band data) ǡ䡢
ѥåȥ⡼ɤεüΥޥ졼¦Ѳ򸫤ĤȤ)
.TP
.B POLLOUT
񤭹ߤ (block) ʤ֤Ǥ롣
.TP
.BR POLLRDHUP " (Linux 2.6.17 ʹ)"
ȥ꡼ॽåȤ¾üͥ close 
ͥν񤭹¦ shutdown 
ͭˤˤϡ
.B _GNU_SOURCE
ǽޥʤФʤʤ
.TP
.B POLLERR
顼 (ϤξΤ)
.TP
.B POLLHUP
ϥ󥰥åפ (ϤξΤ)
.TP
.B POLLNVAL
׵:
.I fd
ץ󤵤Ƥʤ (ϤξΤ)
.RE
.PP
.B _XOPEN_SOURCE
ƥѥ뤷ˤϡʲԤ롣
嵭ΥꥹȤˤӥåȰʾξǤϤʤ
.RS
.TP
.B POLLRDNORM
.B POLLIN
Ʊ
.TP
.B POLLRDBAND
ͥӰǡ (priority band data) ɤ߽ФǽǤ
(̤ Linux ǤϻѤʤ)
.\" POLLRDBAND is used in the DECnet protocol.
.TP
.B POLLWRNORM
.B POLLOUT
Ʊ
.TP
.B POLLWRBAND
ͥӰǡ (priority data) 񤭹߲ǽǤ롣
.RE
.PP
Linux Ǥ
.B POLLMSG
Ƥ뤬ѤƤʤ
.SS ppoll()
.BR poll ()

.BR ppoll ()
δط
.BR select (2)

.BR pselect (2)
δطƱ褦ʤΤǤ:
.BR pselect (2)
Ʊͤˡ
.BR ppoll ()
ȤȡץꥱϥեǥץξѲ
⤷ϥʥªԤĤȤǤ롣
.PP
.I timeout
ΰ㤤ȡʲ
.BR ppoll ()
θƤӽФϡ
.nf

    ready = ppoll(&fds, nfds, timeout, &sigmask);

.fi
Υ
.I atomic
˼¹ԤΤǤ롣
.nf

    sigset_t origmask;

    sigprocmask(SIG_SETMASK, &sigmask, &origmask);
    ready = poll(&fds, nfds, timeout);
    sigprocmask(SIG_SETMASK, &origmask, NULL);
.fi
.PP
ʤ
.BR ppoll ()
ɬפʤΤˤĤƤ
.BR pselect (2)
򻲾ȤΤȡ

.I timeout

.BR ppoll ()
ߤ֤ξ¤ꤹΤǤ롣
ΰˤϰʲηι¤ΤؤΥݥ󥿤ꤹ롣
.in +4n
.nf

struct timespec {
    long    tv_sec;         /* seconds */
    long    tv_nsec;        /* nanoseconds */
};
.fi
.in

.I timeout
 NULL ꤵ줿硢
.B ppoll
̵¤ߤ뤳Ȥ롣
.SH ֤
ο֤ο 0 ʳ
.I revents
ǤŤΤοǤ (̤θ򤹤ȡΥǥץ
ˤϥ٥Ȥ顼𤬤)
 0 ϡॢȤȤʤꡢɤΥեǥץǤ⥤٥Ȥ
ȯʤäȤ򼨤顼ξ \-1 ֤졢
.I errno
Ŭڤꤵ롣
.SH 顼
.TP
.B EBADF
Τɤ줫ʥեǥץޤޤƤ롣
.TP
.B EFAULT
Ȥƻꤷ󤬡ƤӽФץΥɥ쥹֤
ޤޤƤʤ
.TP
.B EINTR
׵ᤵ줿٥ȤΤɤ줫˥ʥ뤬ȯ
.TP
.B EINVAL
.I nfds
ͤ
.B RLIMIT_NOFILE
Ķ
.TP
.B ENOMEM
եǥץơ֥ݤ뤿Υ꤬ʤ
.SH С
.BR poll ()
ƥॳ Linux 2.1.23 Ƴ줿
.BR poll ()
饤֥ꡦ libc 5.4.28 Ƴ줿
(ϥͥ뤬
.BR poll ()
ƥॳ򥵥ݡȤƤʤ
.BR select (2)
Ѥƥߥ졼ȤԤ)

.BR ppoll ()
ƥॳ ͥ 2.6.16  Linux ɲä줿
.BR ppoll ()
饤֥ꥳ glibc 2.4 ɲä줿
.SH 
.BR poll ()
 POSIX.1-2001 ˽򤷤Ƥ롣
.BR ppoll ()
 Linux ͭǤ롣
.\" NetBSD 3.0 ˤ pollts() 롣
.\" pollts()  Linux ppoll () Ʊ褦ʤΤǤ롣
.SH 
ĤμǤϡ \-1 äɸ
.B INFTIM
Ƥꡢ
.I timeout
λ˻ѤǤ롣
 glibc ǤƤʤ
.SS "Linux Ǥ"
Linux 
.BR ppoll ()
ƥॳ
.I timeout
ѹ롣
glibc ΥåѡؿϡƥॳϤ timeout 
ȤƥѿȤȤǤưäƤ롣
Τᡢglibc 
.BR ppoll ()
ؿ
.I timeout
ѹʤ
.SH Х
.BR select (2)
Ρ֥Хפ˽񤫤Ƥ롢äλ (spurious readiness
notifications) ˤĤƤε򻲾ȤΤȡ
.SH Ϣ
.BR select (2),
.BR select_tut (2),
.BR feature_test_macros (7)