(split) Import translated manuals from JM CVS Repository.

[linuxjm/LDP_man-pages.git] / release / man2 / eventfd.2

.\" Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
.\" starting from a version by Davide Libenzi <davidel@xmailserver.org>
.\"
.\" This program is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 2 of the License, or
.\" (at your option) any later version.
.\"
.\" This program is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public License
.\" along with this program; if not, write to the Free Software
.\" Foundation, Inc., 59 Temple Place, Suite 330, Boston,
.\" MA  02111-1307  USA
.\"
.\" 2008-10-10, mtk: describe eventfd2(), and EFD_NONBLOCK and EFD_CLOEXEC
.\"
.\" Japanese Version Copyright (c) 2008  Akihiro MOTOKI
.\"         all rights reserved.
.\" Translated 2008-04-08, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2008-11-10, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v3.13
.\" 
.TH EVENTFD 2 2009-01-26 Linux "Linux Programmer's Manual"
.SH ̾Á°
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typedef uint64_t eventfd_t;

int eventfd_read(int fd, eventfd_t *value);
int eventfd_write(int fd, eventfd_t value);
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.RB "$" " ./a.out 1 2 4 7 14"
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Child writing 2 to efd
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Child writing 14 to efd
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Parent read 28 (0x1c) from efd
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#include <sys/eventfd.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>             /* Definition of uint64_t */

#define handle_error(msg) \\
    do { perror(msg); exit(EXIT_FAILURE); } while (0)

int
main(int argc, char *argv[])
{
    int efd, j;
    uint64_t u;
    ssize_t s;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s <num>...\\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    efd = eventfd(0, 0);
    if (efd == \-1)
        handle_error("eventfd");

    switch (fork()) {
    case 0:
        for (j = 1; j < argc; j++) {
            printf("Child writing %s to efd\\n", argv[j]);
            u = strtoull(argv[j], NULL, 0);
                    /* strtoull() allows various bases */
            s = write(efd, &u, sizeof(uint64_t));
            if (s != sizeof(uint64_t))
                handle_error("write");
        }
        printf("Child completed write loop\\n");

        exit(EXIT_SUCCESS);

    default:
        sleep(2);

        printf("Parent about to read\\n");
        s = read(efd, &u, sizeof(uint64_t));
        if (s != sizeof(uint64_t))
            handle_error("read");
        printf("Parent read %llu (0x%llx) from efd\\n",
                (unsigned long long) u, (unsigned long long) u);
        exit(EXIT_SUCCESS);

    case \-1:
        handle_error("fork");
    }
}
.fi
.SH ´ØÏ¢¹àÌÜ
.BR futex (2),
.BR pipe (2),
.BR poll (2),
.BR read (2),
.BR select (2),
.BR signalfd (2),
.BR timerfd_create (2),
.BR write (2),
.BR epoll (7),
.BR sem_overview (7)