Export device node as property.

There is currently no mapping between XI devices and physical devices other
than what can be extracted by parsing the Xorg logfile. Add new property
"Device Node" to the driver to export the open device file.

Server 1.11 and later standardises on this property name.

The client is responsible for detecting if the device is on the same host
and converting the data into a more useful format (e.g. sysfs path).

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

man/evdev.man

@@ -66,7 +66,8 @@ is used. Buttons not specified in the user's mapping use the default mapping.
 .BI "Option \*qDevice\*q \*q" string \*q
 Specifies the device through which the device can be accessed.  This will 
 generally be of the form \*q/dev/input/eventX\*q, where X is some integer.
-The mapping from device node to hardware is system-dependent.
+The mapping from device node to hardware is system-dependent. Property:
+"Device Node" (read-only).
 .TP 7
 .BI "Option \*qDragLockButtons\*q \*q" "L1 B2 L3 B4" \*q
 Sets \*qdrag lock buttons\*q that simulate holding a button down, so

src/evdev.c

@@ -118,6 +118,7 @@ static Atom prop_calibration;
 static Atom prop_swap;
 static Atom prop_axis_label;
 static Atom prop_btn_label;
+static Atom prop_device;
 
 /* All devices the evdev driver has allocated and knows about.
  * MAXDEVICES is safe as null-terminated array, as two devices (VCP and VCK)
@@ -2263,6 +2264,8 @@ EvdevInitProperty(DeviceIntPtr dev)
     InputInfoPtr pInfo  = dev->public.devicePrivate;
     EvdevPtr     pEvdev = pInfo->private;
     int          rc;
+    char         *device_node;
+
     CARD32       product[2];
 
     prop_product_id = MakeAtom(XI_PROP_PRODUCT_ID, strlen(XI_PROP_PRODUCT_ID), TRUE);
@@ -2275,6 +2278,21 @@ EvdevInitProperty(DeviceIntPtr dev)
 
     XISetDevicePropertyDeletable(dev, prop_invert, FALSE);
 
+    /* Device node property */
+    device_node = strdup(pEvdev->device);
+    prop_device = MakeAtom(XI_PROP_DEVICE_NODE,
+                           strlen(XI_PROP_DEVICE_NODE), TRUE);
+    rc = XIChangeDeviceProperty(dev, prop_device, XA_STRING, 8,
+                                PropModeReplace,
+                                strlen(device_node), device_node,
+                                FALSE);
+    free(device_node);
+
+    if (rc != Success)
+        return;
+
+    XISetDevicePropertyDeletable(dev, prop_device, FALSE);
+
     if (pEvdev->flags & (EVDEV_RELATIVE_EVENTS | EVDEV_ABSOLUTE_EVENTS))
     {
         BOOL invert[2];
@@ -2382,7 +2400,7 @@ EvdevSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
         if (!checkonly)
             pEvdev->swap_axes = *((BOOL*)val->data);
     } else if (atom == prop_axis_label || atom == prop_btn_label ||
-               atom == prop_product_id)
+               atom == prop_product_id || atom == prop_device)
         return BadAccess; /* Read-only properties */
 
     return Success;

src/evdev.h

@@ -80,6 +80,10 @@
 #define MAX_VALUATORS 36
 #endif
 
+#ifndef XI_PROP_DEVICE_NODE
+#define XI_PROP_DEVICE_NODE "Device Node"
+#endif
+
 #define LONG_BITS (sizeof(long) * 8)
 
 /* Number of longs needed to hold the given number of bits */