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 #include "qemu-char.h"
  16
  17 #ifdef CONFIG_EVENTFD
  18 #include <sys/eventfd.h>
  19 #endif
  20
  21 void event_notifier_init_fd(EventNotifier *e, int fd)
  22 {
  23     e->fd = fd;
  24 }
  25
  26 int event_notifier_init(EventNotifier *e, int active)
  27 {
  28 #ifdef CONFIG_EVENTFD
  29     int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC);
  30     if (fd < 0)
  31         return -errno;
  32     e->fd = fd;
  33     return 0;
  34 #else
  35     return -ENOSYS;
  36 #endif
  37 }
  38
  39 void event_notifier_cleanup(EventNotifier *e)
  40 {
  41     close(e->fd);
  42 }
  43
  44 int event_notifier_get_fd(EventNotifier *e)
  45 {
  46     return e->fd;
  47 }
  48
  49 int event_notifier_set_handler(EventNotifier *e,
  50                                EventNotifierHandler *handler)
  51 {
  52     return qemu_set_fd_handler(e->fd, (IOHandler *)handler, NULL, e);
  53 }
  54
  55 int event_notifier_set(EventNotifier *e)
  56 {
  57     uint64_t value = 1;
  58     int r = write(e->fd, &value, sizeof(value));
  59     return r == sizeof(value);
  60 }
  61
  62 int event_notifier_test_and_clear(EventNotifier *e)
  63 {
  64     uint64_t value;
  65     int r = read(e->fd, &value, sizeof(value));
  66     return r == sizeof(value);
  67 }