xkb: if the keymap failed to compile, load the default keymap instead.

We really need symbols, compat, keynames, vmods and types for a sensible keymap.

Try this in your xorg.conf.d snippets for all keyboards:
        Option "XkbLayout" "us"
        Option "XkbVariant" "nodeadkeys"

us(nodeadkeys) doesn't exist so xkbcomp provides everything but the symbols
map. We say we want everything but don't _need_ anything, the server happily
gives us a keymap with every key mapped to NoSymbol. This in turn isn't what
we want after all.

So instead, require symbols, compat, keynames, vmods and types from the
keymap and if that fails, load the default keymap instead. If that fails
too, all bets are off.

Signed-off-by: Peter Hutterer <[email protected]>
Reviewed-by: Dan Nicholson <[email protected]>

xkb/ddxLoad.c

@@ -470,13 +470,34 @@ XkbDescPtr
 XkbCompileKeymap(DeviceIntPtr dev, XkbRMLVOSet *rmlvo)
 {
     XkbDescPtr xkb;
+    unsigned int need;
 
     if (!dev || !rmlvo) {
         LogMessage(X_ERROR, "XKB: No device or RMLVO specified\n");
         return NULL;
     }
 
-    xkb = XkbCompileKeymapForDevice(dev, rmlvo, 0);
+    /* These are the components we really really need */
+    need = XkmSymbolsMask | XkmCompatMapMask | XkmTypesMask |
+           XkmKeyNamesMask | XkmVirtualModsMask;
+
+
+    xkb = XkbCompileKeymapForDevice(dev, rmlvo, need);
+
+    if (!xkb) {
+        XkbRMLVOSet dflts;
+
+        /* we didn't get what we really needed. And that will likely leave
+         * us with a keyboard that doesn't work. Use the defaults instead */
+        LogMessage(X_ERROR, "XKB: Failed to load keymap. Loading default "
+                   "keymap instead.\n");
+
+        XkbGetRulesDflts(&dflts);
+
+        xkb = XkbCompileKeymapForDevice(dev, &dflts, 0);
+
+        XkbFreeRMLVOSet(&dflts, FALSE);
+    }
 
     return xkb;
 }