Archipelago » qemu

/*

 * 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-common.h"

#include "qemu/event_notifier.h"

#include "sysemu/char.h"

#include "qemu/main-loop.h"

#ifdef CONFIG_EVENTFD

#include <sys/eventfd.h>

#endif

void event_notifier_init_fd(EventNotifier *e, int fd)

{

    e->rfd = fd;

    e->wfd = fd;

}

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];

    }

    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);

}

int event_notifier_get_fd(EventNotifier *e)

{

    return e->rfd;

}

int event_notifier_set_handler(EventNotifier *e,

                               EventNotifierHandler *handler)

{

    return qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e);

}

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;

}