event_notifier.c

   1 /*
   2  * event notifier support
   3  *
   4  * Copyright Red Hat, Inc. 2010
   5  *
   6  * Authors:
   7  *  Michael S. Tsirkin <mst@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu-common.h"
  14 #include "event_notifier.h"
  15
  16 #ifdef CONFIG_EVENTFD
  17 #include <sys/eventfd.h>
  18 #endif
  19
  20 void event_notifier_init_fd(EventNotifier *e, int fd)
  21 {
  22     e->fd = fd;
  23 }
  24
  25 int event_notifier_init(EventNotifier *e, int active)
  26 {
  27 #ifdef CONFIG_EVENTFD
  28     int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC);
  29     if (fd < 0)
  30         return -errno;
  31     e->fd = fd;
  32     return 0;
  33 #else
  34     return -ENOSYS;
  35 #endif
  36 }
  37
  38 void event_notifier_cleanup(EventNotifier *e)
  39 {
  40     close(e->fd);
  41 }
  42
  43 int event_notifier_get_fd(EventNotifier *e)
  44 {
  45     return e->fd;
  46 }
  47
  48 int event_notifier_set(EventNotifier *e)
  49 {
  50     uint64_t value = 1;
  51     int r = write(e->fd, &value, sizeof(value));
  52     return r == sizeof(value);
  53 }
  54
  55 int event_notifier_test_and_clear(EventNotifier *e)
  56 {
  57     uint64_t value;
  58     int r = read(e->fd, &value, sizeof(value));
  59     return r == sizeof(value);
  60 }