[PATCH libinput] Add a libinput_device_get_udev_devices() call for merged devices

[Peter Hutterer]

Merged devices may comprise of multiple event nodes. To get those we need to
return all udev devices we have.

This patch still leaves the backend where it is (one evdev device per libinput
device) and merely introduces the new API.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
This is preparation work for the tablet support bits where we will end up
merging multiple devices into one struct libinput_device.

 src/libinput.c   | 10 ++++++++++
 src/libinput.h   | 43 ++++++++++++++++++++++++++++++++++++++++++-
 src/libinput.sym |  1 +
 test/device.c    | 31 +++++++++++++++++++++++++++++++
 4 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/src/libinput.c b/src/libinput.c
index 39c4ef6..6185651 100644
--- a/src/libinput.c
+++ b/src/libinput.c
@@ -1414,6 +1414,16 @@ libinput_device_get_udev_device(struct libinput_device *device)
 	return evdev_device_get_udev_device((struct evdev_device *)device);
 }
 
+LIBINPUT_EXPORT size_t
+libinput_device_get_udev_devices(struct libinput_device *device,
+				 struct udev_device **udev_devices,
+				 size_t ndevices)
+{
+	if (ndevices > 0)
+		udev_devices[0] = evdev_device_get_udev_device((struct evdev_device *)device);
+	return 1;
+}
+
 LIBINPUT_EXPORT void
 libinput_device_led_update(struct libinput_device *device,
 			   enum libinput_led leds)
diff --git a/src/libinput.h b/src/libinput.h
index 59a841f..4cb8fe8 100644
--- a/src/libinput.h
+++ b/src/libinput.h
@@ -1561,6 +1561,9 @@ libinput_device_set_seat_logical_name(struct libinput_device *device,
 /**
  * @ingroup device
  *
+ * @deprecated This function is deprecated and always returns the first udev
+ * device. Use libinput_device_get_udev_devices() instead.
+ *
  * Return a udev handle to the device that is this libinput device, if any.
  * The returned handle has a refcount of at least 1, the caller must call
  * udev_device_unref() once to release the associated resources.
@@ -1576,7 +1579,45 @@ libinput_device_set_seat_logical_name(struct libinput_device *device,
  * @retval NULL This device is not represented by a udev device
  */
 struct udev_device *
-libinput_device_get_udev_device(struct libinput_device *device);
+libinput_device_get_udev_device(struct libinput_device *device)
+	LIBINPUT_ATTRIBUTE_DEPRECATED;
+
+/**
+ * @ingroup device
+ *
+ * Return the udev handles for the devices that make up this libinput
+ * device, if any. The returned handles have a refcount of at least 1, the
+ * caller must call udev_device_unref() once on each device to release the
+ * associated resources.
+ *
+ * This function returns the number of available udev handles for this
+ * device, but writes at most ndevices handles into the udev_devices array.
+ *
+ * Some devices may not have a udev device, or the udev device may be
+ * unobtainable. This function returns 0 if no udev device was available.
+ * Some libinput devices may be composed of multiple devices, not all of
+ * which have a corresponding udev device. In this case, this function
+ * returns all available udev devices.
+ *
+ * A device may be composed of multiple device nodes, these may appear or
+ * disappear at any time. The list of udev devices can only be considered
+ * static once all events have been processed until the next call to
+ * libinput_dispatch().
+ *
+ * Calling this function multiple times for the same device may not
+ * return the same udev handles each time.
+ *
+ * @param device A previously obtained device
+ * @param udev_devices A pre-allocated array that will be filled with up to
+ * ndevices udev handles.
+ * @param ndevices Number of elements in udev_devices
+ * @return The number of udev handles available for this device.
+ * @retval 0 This device is not represented by a udev device
+ */
+size_t
+libinput_device_get_udev_devices(struct libinput_device *device,
+				 struct udev_device **udev_devices,
+				 size_t ndevices);
 
 /**
  * @ingroup device
diff --git a/src/libinput.sym b/src/libinput.sym
index 671930e..32d39d5 100644
--- a/src/libinput.sym
+++ b/src/libinput.sym
@@ -127,5 +127,6 @@ global:
 	libinput_device_config_click_get_method;
 	libinput_device_config_click_get_methods;
 	libinput_device_config_click_set_method;
+	libinput_device_get_udev_devices;
 	libinput_event_get_device_capability_event;
 } LIBINPUT_0.8.0;
diff --git a/test/device.c b/test/device.c
index 76486f0..2e7a3bb 100644
--- a/test/device.c
+++ b/test/device.c
@@ -639,6 +639,8 @@ START_TEST(device_ids)
 }
 END_TEST
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 START_TEST(device_get_udev_handle)
 {
 	struct litest_device *dev = litest_current_device();
@@ -649,6 +651,34 @@ START_TEST(device_get_udev_handle)
 	udev_device_unref(udev_device);
 }
 END_TEST
+#pragma GCC diagnostic pop
+
+START_TEST(device_get_udev_handles)
+{
+	struct litest_device *dev = litest_current_device();
+	struct udev_device *udev_devices[3];
+	size_t ndevices;
+
+	udev_devices[1] = (struct udev_device *)0xab;
+	udev_devices[2] = (struct udev_device *)0xcd;
+
+	ndevices = libinput_device_get_udev_devices(dev->libinput_device,
+						    udev_devices,
+						    3);
+	ck_assert_int_eq(ndevices, 1);
+	ck_assert_notnull(udev_devices[0]);
+	udev_device_unref(udev_devices[0]);
+	ck_assert_ptr_eq(udev_devices[1], 0xab);
+	ck_assert_ptr_eq(udev_devices[2], 0xcd);
+
+	udev_devices[0] = (struct udev_device *)0xef;
+	ndevices = libinput_device_get_udev_devices(dev->libinput_device,
+						    udev_devices,
+						    0);
+	ck_assert_int_eq(ndevices, 1);
+	ck_assert_ptr_eq(udev_devices[0], 0xef);
+}
+END_TEST
 
 START_TEST(device_context)
 {
@@ -685,6 +715,7 @@ int main (int argc, char **argv)
 	litest_add_for_device("device:context", device_context, LITEST_SYNAPTICS_CLICKPAD);
 
 	litest_add("device:udev", device_get_udev_handle, LITEST_ANY, LITEST_ANY);
+	litest_add("device:udev", device_get_udev_handles, LITEST_ANY, LITEST_ANY);
 
 	return litest_run(argc, argv);
 }
-- 
2.1.0