libudev: queue provide file descriptor to watch busy event queue

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

3 files changed, 50 insertions, 0 deletions

diff --git a/src/libudev/libudev-queue.c b/src/libudev/libudev-queue.c
index c32a7ef709..d4334b440d 100644
--- a/src/libudev/libudev-queue.c
+++ b/src/libudev/libudev-queue.c
@@ -26,6 +26,7 @@
 #include <string.h>
 #include <limits.h>
 #include <sys/stat.h>
+#include <sys/inotify.h>
 
 #include "libudev.h"
 #include "libudev-private.h"
@@ -45,6 +46,7 @@
 struct udev_queue {
         struct udev *udev;
         int refcount;
+        int fd;
 };
 
 /**
@@ -69,6 +71,7 @@ _public_ struct udev_queue *udev_queue_new(struct udev *udev)
 
         udev_queue->refcount = 1;
         udev_queue->udev = udev;
+        udev_queue->fd = -1;
         return udev_queue;
 }
 
@@ -107,6 +110,8 @@ _public_ struct udev_queue *udev_queue_unref(struct udev_queue *udev_queue)
         if (udev_queue->refcount > 0)
                 return NULL;
 
+        safe_close(udev_queue->fd);
+
         free(udev_queue);
         return NULL;
 }
@@ -222,3 +227,44 @@ _public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_qu
 {
         return NULL;
 }
+
+/**
+ * udev_queue_get_fd:
+ * @udev_queue: udev queue context
+ *
+ * Returns: a file descriptor to watch for a queue to become empty.
+ */
+_public_ int udev_queue_get_fd(struct udev_queue *udev_queue) {
+        int fd;
+        int r;
+
+        if (udev_queue->fd >= 0)
+                return udev_queue->fd;
+
+        fd = inotify_init1(IN_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        r = inotify_add_watch(fd, "/run/udev/queue" , IN_DELETE);
+        if (r < 0) {
+                r = -errno;
+                close(fd);
+                return r;
+        }
+
+        udev_queue->fd = fd;
+        return fd;
+}
+
+/**
+ * udev_queue_flush:
+ * @udev_queue: udev queue context
+ *
+ * Returns: the result of clearing the watch for queue changes.
+ */
+_public_ int udev_queue_flush(struct udev_queue *udev_queue) {
+        if (udev_queue->fd < 0)
+                return -EINVAL;
+
+        return flush_fd(udev_queue->fd);
+}
diff --git a/src/libudev/libudev.h b/src/libudev/libudev.h
index ceb89bd593..4f2f11502c 100644
--- a/src/libudev/libudev.h
+++ b/src/libudev/libudev.h
@@ -177,6 +177,8 @@ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue);
 int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum) __attribute__ ((deprecated));
 int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
                                                unsigned long long int start, unsigned long long int end) __attribute__ ((deprecated));
+int udev_queue_get_fd(struct udev_queue *udev_queue);
+int udev_queue_flush(struct udev_queue *udev_queue);
 struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue) __attribute__ ((deprecated));
 
 /*
diff --git a/src/libudev/libudev.sym b/src/libudev/libudev.sym
index 920e7e61eb..7062e29bda 100644
--- a/src/libudev/libudev.sym
+++ b/src/libudev/libudev.sym
@@ -82,6 +82,8 @@ global:
         udev_queue_get_udev;
         udev_queue_get_udev_is_active;
         udev_queue_get_udev_seqnum;
+        udev_queue_get_fd;
+        udev_queue_flush;
         udev_queue_new;
         udev_queue_ref;
         udev_queue_unref;