Import QEMU upstream snapshot d2e570c

Upstream: https://gitlab.com/qemu-project/qemu.git

Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475

util/event_notifier-posix.c

@@ -0,0 +1,145 @@
+/*
+ * event notifier support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <[email protected]>
+ *
+ * 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 "qapi/error.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->initialized = true;
+}
+#endif
+
+int event_notifier_init(EventNotifier *e, int active)
+{
+    int fds[2];
+    int ret;
+    Error *local_err = NULL;
+
+#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 (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
+            return -errno;
+        }
+        if (!qemu_set_blocking(fds[0], false, &local_err)) {
+            ret = -errno;
+            goto fail;
+        }
+        if (!qemu_set_blocking(fds[1], false, &local_err)) {
+            ret = -errno;
+            goto fail;
+        }
+        e->rfd = fds[0];
+        e->wfd = fds[1];
+    }
+    e->initialized = true;
+    if (active) {
+        event_notifier_set(e);
+    }
+    return 0;
+
+fail:
+    error_report_err(local_err);
+    close(fds[0]);
+    close(fds[1]);
+    return ret;
+}
+
+void event_notifier_cleanup(EventNotifier *e)
+{
+    if (!e->initialized) {
+        return;
+    }
+
+    if (e->rfd != e->wfd) {
+        close(e->rfd);
+    }
+
+    e->rfd = -1;
+    close(e->wfd);
+    e->wfd = -1;
+    e->initialized = false;
+}
+
+int event_notifier_get_fd(const EventNotifier *e)
+{
+    return e->rfd;
+}
+
+int event_notifier_get_wfd(const EventNotifier *e)
+{
+    return e->wfd;
+}
+
+int event_notifier_set(EventNotifier *e)
+{
+    static const uint64_t value = 1;
+    ssize_t ret;
+
+    if (!e->initialized) {
+        return -1;
+    }
+
+    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];
+
+    if (!e->initialized) {
+        return 0;
+    }
+
+    /* 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;
+}