Add keymap component

Adding a new keymap component that will
indicate the current keyboard layout (language)
and variant if any was set. I use the
standard X11 XKB APIs to retrieve and parse
the xkb_symbols set with setxkbmap.

components/keymap.c

@@ -0,0 +1,97 @@
+/* See LICENSE file for copyright and license details. */
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+#include <X11/XKBlib.h>
+#include <X11/Xlib.h>
+
+#include "../util.h"
+
+#define LAYOUT_MAX 256
+
+/* Given a token (sym) from the xkb_symbols string
+ * check whether it is a valid layout/variant. The
+ * EXCLUDES array contains invalid layouts/variants
+ * that are part of the xkb rules config.
+ */
+static int
+IsLayoutOrVariant(char *sym)
+{
+	static const char* EXCLUDES[] = { "evdev", "inet", "pc", "base" };
+
+	size_t i;
+	for (i = 0; i < sizeof(EXCLUDES)/sizeof(EXCLUDES[0]); ++i)
+		if (strstr(sym, EXCLUDES[i])) {
+			return 0;
+		}
+
+	return 1;
+}
+
+static void
+GetKeyLayout(char *syms, char layout[], int groupNum)
+{
+	char *token, *copy, *delims;
+	int group;
+
+	delims = "+:";
+	group = 0;
+	copy = strdup(syms);
+	token = strtok(copy, delims);
+	while (token != NULL && group <= groupNum) {
+		/* Ignore :2,:3,:4 which represent additional layout
+ 		 * groups
+ 		 */
+		if (IsLayoutOrVariant(token)
+		    && !(strlen(token) == 1 && isdigit(token[0]))) {
+			strncpy (layout, token, LAYOUT_MAX);
+			group++;
+		}
+
+		token = strtok(NULL,delims);
+	}
+
+	free(copy);
+}
+
+const char *
+keymap(void)
+{
+	static char layout[LAYOUT_MAX];
+
+	Display *dpy;
+	char *symbols = NULL;
+	XkbDescRec* desc = NULL;
+
+	memset(layout, '\0', LAYOUT_MAX);
+
+	if (!(dpy = XOpenDisplay(NULL))) {
+		warn("XOpenDisplay: Failed to open display");
+		return NULL;
+	}
+
+	;
+	if (!(desc = XkbAllocKeyboard())) {
+		warn("XkbAllocKeyboard: failed to allocate keyboard");
+		XCloseDisplay(dpy);
+		return NULL;
+	}
+
+	XkbGetNames(dpy, XkbSymbolsNameMask, desc);
+	if (desc->names) {
+		XkbStateRec state;
+		XkbGetState(dpy, XkbUseCoreKbd, &state);
+
+		symbols = XGetAtomName(dpy, desc->names->symbols);
+		GetKeyLayout(symbols, layout, state.group);
+		XFree(symbols);
+	} else {
+		warn("XkbGetNames: failed to retrieve symbols for keys");
+		return NULL;
+	}
+
+	XkbFreeKeyboard(desc, XkbSymbolsNameMask, 1);
+	XCloseDisplay(dpy);
+
+	return layout;
+}