usr/src/lib/libc/port/sys/eventfd.c

   1 /*
   2  * This file and its contents are supplied under the terms of the
   3  * Common Development and Distribution License ("CDDL"), version 1.0.
   4  * You may only use this file in accordance with the terms of version
   5  * 1.0 of the CDDL.
   6  *
   7  * A full copy of the text of the CDDL should have accompanied this
   8  * source.  A copy of the CDDL is also available via the Internet at
   9  * http://www.illumos.org/license/CDDL.
  10  */
  11
  12 /*
  13  * Copyright (c) 2015, Joyent, Inc.  All rights reserved.
  14  */
  15
  16 #include <sys/eventfd.h>
  17 #include <sys/stat.h>
  18 #include <unistd.h>
  19 #include <errno.h>
  20 #include <fcntl.h>
  21
  22 int
  23 eventfd(unsigned int initval, int flags)
  24 {
  25         int oflags = O_RDWR;
  26         uint64_t val = initval;
  27         int fd;
  28
  29         if (flags & ~(EFD_NONBLOCK | EFD_CLOEXEC | EFD_SEMAPHORE)) {
  30                 errno = EINVAL;
  31                 return (-1);
  32         }
  33
  34         if (flags & EFD_NONBLOCK)
  35                 oflags |= O_NONBLOCK;
  36
  37         if (flags & EFD_CLOEXEC)
  38                 oflags |= O_CLOEXEC;
  39
  40         if ((fd = open("/dev/eventfd", oflags)) < 0)
  41                 return (-1);
  42
  43         if ((flags & EFD_SEMAPHORE) &&
  44             ioctl(fd, EVENTFDIOC_SEMAPHORE, 0) != 0) {
  45                 (void) close(fd);
  46                 return (-1);
  47         }
  48
  49         if (write(fd, &val, sizeof (val)) < sizeof (val)) {
  50                 (void) close(fd);
  51                 return (-1);
  52         }
  53
  54         return (fd);
  55 }
  56
  57 int
  58 eventfd_read(int fd, eventfd_t *valp)
  59 {
  60         return (read(fd, valp, sizeof (*valp)) < sizeof (*valp) ? -1 : 0);
  61 }
  62
  63 int
  64 eventfd_write(int fd, eventfd_t val)
  65 {
  66         return (write(fd, &val, sizeof (val)) < sizeof (val) ? -1 : 0);
  67 }