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/*
* event notifier support
*
* Copyright Red Hat, Inc. 2010
*
* Authors:
* Michael S. Tsirkin <mst@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/cutils.h"
#include "qemu/event_notifier.h"
#include "qemu/main-loop.h"
#ifdef CONFIG_EVENTFD
#include <sys/eventfd.h>
#endif
#ifdef CONFIG_EVENTFD
/*
* Initialize @e with existing file descriptor @fd.
* @fd must be a genuine eventfd object, emulation with pipe won't do.
*/
void event_notifier_init_fd(EventNotifier *e, int fd)
{
e->rfd = fd;
e->wfd = fd;
e->cleanup = NULL;
}
#endif
int event_notifier_init(EventNotifier *e, int active)
{
int fds[2];
int ret;
#ifdef CONFIG_EVENTFD
ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
#else
ret = -1;
errno = ENOSYS;
#endif
if (ret >= 0) {
e->rfd = e->wfd = ret;
} else {
if (errno != ENOSYS) {
return -errno;
}
if (qemu_pipe(fds) < 0) {
return -errno;
}
ret = fcntl_setfl(fds[0], O_NONBLOCK);
if (ret < 0) {
ret = -errno;
goto fail;
}
ret = fcntl_setfl(fds[1], O_NONBLOCK);
if (ret < 0) {
ret = -errno;
goto fail;
}
e->rfd = fds[0];
e->wfd = fds[1];
}
e->cleanup = NULL;
if (active) {
event_notifier_set(e);
}
return 0;
fail:
close(fds[0]);
close(fds[1]);
return ret;
}
void event_notifier_cleanup(EventNotifier *e)
{
if (e->rfd != e->wfd) {
close(e->rfd);
}
close(e->wfd);
e->rfd = -1;
e->wfd = -1;
e->cleanup = NULL;
}
int event_notifier_get_fd(const EventNotifier *e)
{
return e->rfd;
}
int event_notifier_set(EventNotifier *e)
{
static const uint64_t value = 1;
ssize_t ret;
do {
ret = write(e->wfd, &value, sizeof(value));
} while (ret < 0 && errno == EINTR);
/* EAGAIN is fine, a read must be pending. */
if (ret < 0 && errno != EAGAIN) {
return -errno;
}
return 0;
}
int event_notifier_test_and_clear(EventNotifier *e)
{
int value;
ssize_t len;
char buffer[512];
/* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
value = 0;
do {
len = read(e->rfd, buffer, sizeof(buffer));
value |= (len > 0);
} while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
return value;
}
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