Implement support for using key symbols in configuration file

Use "bindsym" instead of "bind". You have to use the names of keys
as in xmodmap. To get a list of currently bounud symbols, use
xmodmap -pke

Technical quirk: Xlib generated MappingNotify events upon
XkbMapNotify events (from XKB, as the name says). XCB does not yet
have support for XKB, thus we need to select and handle the event
by ourself. Hopefully, this will change in the future.

src/mainx.c

@@ -18,6 +18,7 @@
 #include <assert.h>
 #include <limits.h>
 #include <locale.h>
+#include <fcntl.h>
 
 #include <X11/XKBlib.h>
 #include <X11/extensions/XKB.h>
@@ -55,6 +56,8 @@ char **start_argv;
 /* This is our connection to X11 for use with XKB */
 Display *xkbdpy;
 
+xcb_key_symbols_t *keysyms;
+
 /* The list of key bindings */
 struct bindings_head bindings = TAILQ_HEAD_INITIALIZER(bindings);
 
@@ -109,6 +112,34 @@ static void xcb_check_cb(EV_P_ ev_check *w, int revents) {
         }
 }
 
+/*
+ * When using xmodmap to change the keyboard mapping, this event
+ * is only sent via XKB. Therefore, we need this special handler.
+ *
+ */
+static void xkb_got_event(EV_P_ struct ev_io *w, int revents) {
+        LOG("got xkb event, yay\n");
+        XEvent ev;
+        /* When using xmodmap, every change (!) gets an own event.
+         * Therefore, we just read all events and only handle the
+         * mapping_notify once (we do not receive any other XKB
+         * events anyway). */
+        while (XPending(xkbdpy))
+                XNextEvent(xkbdpy, &ev);
+
+        xcb_key_symbols_free(keysyms);
+        keysyms = xcb_key_symbols_alloc(global_conn);
+
+        xcb_get_numlock_mask(global_conn);
+
+        ungrab_all_keys(global_conn);
+        LOG("Re-grabbing...\n");
+        grab_all_keys(global_conn);
+        LOG("Done\n");
+
+}
+
+
 int main(int argc, char *argv[], char *env[]) {
         int i, screens, opt;
         char *override_configpath = NULL;
@@ -193,6 +224,11 @@ int main(int argc, char *argv[], char *env[]) {
                 return 1;
         }
 
+        if (fcntl(ConnectionNumber(xkbdpy), F_SETFD, FD_CLOEXEC) == -1) {
+                fprintf(stderr, "Could not set FD_CLOEXEC on xkbdpy\n");
+                return 1;
+        }
+
         int i1;
         if (!XkbQueryExtension(xkbdpy,&i1,&evBase,&errBase,&major,&minor)) {
                 fprintf(stderr, "XKB not supported by X-server\n");
@@ -200,18 +236,30 @@ int main(int argc, char *argv[], char *env[]) {
         }
         /* end of ugliness */
 
+        if (!XkbSelectEvents(xkbdpy, XkbUseCoreKbd, XkbMapNotifyMask, XkbMapNotifyMask)) {
+                fprintf(stderr, "Could not set XKB event mask\n");
+                return 1;
+        }
+
         /* Initialize event loop using libev */
         struct ev_loop *loop = ev_default_loop(0);
         if (loop == NULL)
                 die("Could not initialize libev. Bad LIBEV_FLAGS?\n");
 
         struct ev_io *xcb_watcher = scalloc(sizeof(struct ev_io));
+        struct ev_io *xkb = scalloc(sizeof(struct ev_io));
         struct ev_check *xcb_check = scalloc(sizeof(struct ev_check));
         struct ev_prepare *xcb_prepare = scalloc(sizeof(struct ev_prepare));
 
         ev_io_init(xcb_watcher, xcb_got_event, xcb_get_file_descriptor(conn), EV_READ);
         ev_io_start(loop, xcb_watcher);
 
+        ev_io_init(xkb, xkb_got_event, ConnectionNumber(xkbdpy), EV_READ);
+        ev_io_start(loop, xkb);
+
+        /* Flush the buffer so that libev can properly get new events */
+        XFlush(xkbdpy);
+
         ev_check_init(xcb_check, xcb_check_cb);
         ev_check_start(loop, xcb_check);
 
@@ -261,6 +309,9 @@ int main(int argc, char *argv[], char *env[]) {
          * cross virtual screen boundaries doing that) */
         xcb_event_set_motion_notify_handler(&evenths, handle_motion_notify, NULL);
 
+        /* Mapping notify = keyboard mapping changed (Xmodmap), re-grab bindings */
+        xcb_event_set_mapping_notify_handler(&evenths, handle_mapping_notify, NULL);
+
         /* Client message are sent to the root window. The only interesting client message
            for us is _NET_WM_STATE, we honour _NET_WM_STATE_FULLSCREEN */
         xcb_event_set_client_message_handler(&evenths, handle_client_message, NULL);
@@ -341,6 +392,8 @@ int main(int argc, char *argv[], char *env[]) {
         xcb_change_property(conn, XCB_PROP_MODE_REPLACE, root, atoms[_NET_SUPPORTING_WM_CHECK], WINDOW, 32, 1, &root);
         xcb_change_property(conn, XCB_PROP_MODE_REPLACE, root, atoms[_NET_WM_NAME], atoms[UTF8_STRING], 8, strlen("i3"), "i3");
 
+        keysyms = xcb_key_symbols_alloc(conn);
+
         xcb_get_numlock_mask(conn);
 
         grab_all_keys(conn);