Add per-device log handlers

The global log handler isn't a good choice for a low-level library. In the
caser of the X server, both evdev and synaptics are now using the libevdev but
are loaded from the same server process. Thus, there's only one log handler,
but evdev and synaptics don't talk to each other (a bit childish, I know).

Add a per-device log handler that overrides the global log handler, and fall
back to the global log handler if no device log handler is set. The log
macros take care of that automatically, especially as we can't do per-device
log handlers for the uinput code.

Note that we use the same struct for the global and device logging, so in each
instance one of the two function pointers is NULL. Suicide triggers are in
place in case we mess that up.

This also makes libevdev_new_from_fd() a bit less useful since we can't set
the log handler beforehand.

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

1 files changed, 74 insertions, 26 deletions

diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index a316831..903a286 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -48,11 +48,11 @@ static inline int*
 slot_value(const struct libevdev *dev, int slot, int axis)
 {
 	if (unlikely(slot > dev->num_slots)) {
-		log_bug("Slot %d exceeds number of slots (%d)\n", slot, dev->num_slots);
+		log_bug(dev, "Slot %d exceeds number of slots (%d)\n", slot, dev->num_slots);
 		slot = 0;
 	}
 	if (unlikely(axis < ABS_MT_MIN || axis > ABS_MT_MAX)) {
-		log_bug("MT axis %d is outside the valid range [%d,%d]\n",
+		log_bug(dev, "MT axis %d is outside the valid range [%d,%d]\n",
 			axis, ABS_MT_MIN, ABS_MT_MAX);
 		axis = ABS_MT_MIN;
 	}
@@ -129,31 +129,52 @@ libevdev_dflt_log_func(enum libevdev_log_priority priority,
 /*
  * Global logging settings.
  */
-struct logdata log_data = {
-	LIBEVDEV_LOG_INFO,
-	libevdev_dflt_log_func,
-	NULL,
+static struct logdata log_data = {
+	.priority = LIBEVDEV_LOG_INFO,
+	.global_handler = libevdev_dflt_log_func,
+	.userdata = NULL,
 };
 
 void
-log_msg(enum libevdev_log_priority priority,
-	void *data,
+log_msg(const struct libevdev *dev,
+	enum libevdev_log_priority priority,
 	const char *file, int line, const char *func,
 	const char *format, ...)
 {
 	va_list args;
 
-	if (!log_data.handler || priority > log_data.priority)
+	if (dev && dev->log.device_handler) {
+		/**
+		 * if a global handler is set for a device does
+		 * we've set up the handlers wrong.  And that means we'll
+		 * likely get the printf args wrong and cause all sorts of
+		 * mayhem. Seppuku is called for.
+		 */
+		if (unlikely(dev->log.global_handler))
+			abort();
+
+		if (priority > dev->log.priority)
+			return;
+	} else if (!log_data.global_handler || priority > log_data.priority)
 		return;
+	else if (unlikely(log_data.device_handler))
+		abort(); /* Seppuku, see above */
+
 
 	va_start(args, format);
-	log_data.handler(priority, data, file, line, func, format, args);
+	if (dev && dev->log.device_handler)
+		dev->log.device_handler(dev, priority, dev->log.userdata, file, line, func, format, args);
+	else
+		log_data.global_handler(priority, log_data.userdata, file, line, func, format, args);
 	va_end(args);
 }
 
 static void
 libevdev_reset(struct libevdev *dev)
 {
+	enum libevdev_log_priority pri = dev->log.priority;
+	libevdev_device_log_func_t handler = dev->log.device_handler;
+
 	free(dev->name);
 	free(dev->phys);
 	free(dev->uniq);
@@ -168,6 +189,8 @@ libevdev_reset(struct libevdev *dev)
 	dev->current_slot = -1;
 	dev->grabbed = LIBEVDEV_UNGRAB;
 	dev->sync_state = SYNC_NONE;
+	dev->log.priority = pri;
+	dev->log.device_handler = handler;
 	libevdev_enable_event_type(dev, EV_SYN);
 }
 
@@ -217,7 +240,7 @@ libevdev_free(struct libevdev *dev)
 LIBEVDEV_EXPORT void
 libevdev_set_log_function(libevdev_log_func_t logfunc, void *data)
 {
-	log_data.handler = logfunc;
+	log_data.global_handler = logfunc;
 	log_data.userdata = data;
 }
 
@@ -235,11 +258,36 @@ libevdev_get_log_priority(void)
 	return log_data.priority;
 }
 
+LIBEVDEV_EXPORT void
+libevdev_set_device_log_function(struct libevdev *dev,
+				 libevdev_device_log_func_t logfunc,
+				 enum libevdev_log_priority priority,
+				 void *data)
+{
+	if (!dev) {
+		log_bug(NULL, "device must not be NULL\n");
+		return;
+	}
+
+	dev->log.priority = priority;
+	dev->log.device_handler = logfunc;
+	dev->log.userdata = data;
+}
+
+enum libevdev_log_priority
+log_priority(const struct libevdev *dev)
+{
+	if (dev && dev->log.device_handler)
+		return dev->log.priority;
+	else
+		return libevdev_get_log_priority();
+}
+
 LIBEVDEV_EXPORT int
 libevdev_change_fd(struct libevdev *dev, int fd)
 {
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -1;
 	}
 	dev->fd = fd;
@@ -254,7 +302,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	char buf[256];
 
 	if (dev->initialized) {
-		log_bug("device already initialized.\n");
+		log_bug(dev, "device already initialized.\n");
 		return -EBADF;
 	} else if (fd < 0)
 		return -EBADF;
@@ -743,7 +791,7 @@ drain_events(struct libevdev *dev)
 			return;
 
 		if (rc < 0) {
-			log_error("Failed to drain events before sync.\n");
+			log_error(dev, "Failed to drain events before sync.\n");
 			return;
 		}
 
@@ -758,7 +806,7 @@ drain_events(struct libevdev *dev)
 	   we can drain them.
 	 */
 	if (iterations >= max_iterations)
-		log_info("Unable to drain events, buffer size mismatch.\n");
+		log_info(dev, "Unable to drain events, buffer size mismatch.\n");
 }
 
 static int
@@ -913,7 +961,7 @@ sanitize_event(const struct libevdev *dev,
 	if (unlikely(dev->num_slots > -1 &&
 		     libevdev_event_is_code(ev, EV_ABS, ABS_MT_SLOT) &&
 		     (ev->value < 0 || ev->value >= dev->num_slots))) {
-		log_bug("Device \"%s\" received an invalid slot index %d."
+		log_bug(dev, "Device \"%s\" received an invalid slot index %d."
 				"Capping to announced max slot number %d.\n",
 				dev->name, ev->value, dev->num_slots - 1);
 		ev->value = dev->num_slots - 1;
@@ -930,7 +978,7 @@ sanitize_event(const struct libevdev *dev,
 			     *slot_value(dev, dev->current_slot, ABS_MT_TRACKING_ID) == -1) ||
 			     (ev->value != -1 &&
 			     *slot_value(dev, dev->current_slot, ABS_MT_TRACKING_ID) != -1)))) {
-		log_bug("Device \"%s\" received a double tracking ID %d in slot %d.\n",
+		log_bug(dev, "Device \"%s\" received a double tracking ID %d in slot %d.\n",
 			dev->name, ev->value, dev->current_slot);
 		return EVENT_FILTER_DISCARD;
 	}
@@ -945,13 +993,13 @@ libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event
 	enum event_filter_status filter_status;
 
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;
 
 	if (!(flags & (LIBEVDEV_READ_FLAG_NORMAL|LIBEVDEV_READ_FLAG_SYNC|LIBEVDEV_READ_FLAG_FORCE_SYNC))) {
-		log_bug("invalid flags %#x\n.\n", flags);
+		log_bug(dev, "invalid flags %#x\n.\n", flags);
 		return -EINVAL;
 	}
 
@@ -1029,7 +1077,7 @@ libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event
 
 			if (queue_peek(dev, 0, &next) == 0 &&
 			    next.type == EV_SYN && next.code == SYN_DROPPED)
-				log_info("SYN_DROPPED received after finished "
+				log_info(dev, "SYN_DROPPED received after finished "
 					 "sync - you're not keeping up\n");
 		}
 	}
@@ -1045,7 +1093,7 @@ libevdev_has_event_pending(struct libevdev *dev)
 	int rc;
 
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;
@@ -1451,7 +1499,7 @@ libevdev_kernel_set_abs_info(struct libevdev *dev, unsigned int code, const stru
 	int rc;
 
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;
@@ -1474,13 +1522,13 @@ libevdev_grab(struct libevdev *dev, enum libevdev_grab_mode grab)
 	int rc = 0;
 
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;
 
 	if (grab != LIBEVDEV_GRAB && grab != LIBEVDEV_UNGRAB) {
-		log_bug("invalid grab parameter %#x\n", grab);
+		log_bug(dev, "invalid grab parameter %#x\n", grab);
 		return -EINVAL;
 	}
 
@@ -1585,7 +1633,7 @@ libevdev_kernel_set_led_values(struct libevdev *dev, ...)
 	size_t nleds = 0;
 
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;
@@ -1641,7 +1689,7 @@ LIBEVDEV_EXPORT int
 libevdev_set_clock_id(struct libevdev *dev, int clockid)
 {
 	if (!dev->initialized) {
-		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		log_bug(dev, "device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
 	} else if (dev->fd < 0)
 		return -EBADF;