Reset the struct on set_fd

libevdev_set_fd may fail at a number of points. If it does, it errors out but does nothing
otherwise. Thus, a client may call set_fd again for the same struct but on a different fd and have
it succeed. Depending on when set_fd bailed out the first time, some fields may already be set.

Thus, reset the whole struct at set_fd time to make sure we're nulled out appropriately.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>

1 files changed, 19 insertions, 7 deletions

diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 6f203e2..d84e67e 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -110,20 +110,28 @@ log_msg(enum libevdev_log_priority priority,
 	va_end(args);
 }
 
-LIBEVDEV_EXPORT struct libevdev*
-libevdev_new(void)
+static void
+libevdev_reset(struct libevdev *dev)
 {
-	struct libevdev *dev;
-
-	dev = calloc(1, sizeof(*dev));
-	if (!dev)
-		return NULL;
+	memset(dev, 0, sizeof(*dev));
 	dev->fd = -1;
 	dev->initialized = false;
 	dev->num_slots = -1;
 	dev->current_slot = -1;
 	dev->grabbed = LIBEVDEV_UNGRAB;
 	dev->sync_state = SYNC_NONE;
+}
+
+LIBEVDEV_EXPORT struct libevdev*
+libevdev_new(void)
+{
+	struct libevdev *dev;
+
+	dev = malloc(sizeof(*dev));
+	if (!dev)
+		return NULL;
+
+	libevdev_reset(dev);
 
 	return dev;
 }
@@ -212,6 +220,8 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	} else if (fd < 0)
 		return -EBADF;
 
+	libevdev_reset(dev);
+
 	rc = ioctl(fd, EVIOCGBIT(0, sizeof(dev->bits)), dev->bits);
 	if (rc < 0)
 		goto out;
@@ -360,6 +370,8 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 
 	dev->initialized = true;
 out:
+	if (rc)
+		libevdev_reset(dev);
 	return rc ? -errno : 0;
 }