Add --pass-volume-keys option to just pass volume keys

i3lock.1

@@ -199,6 +199,11 @@ XF86MonBrightnessUp, XF86MonBrightnessDown.
 Allow the following keys to be used while the screen is locked by passing them through:
 XF86PowerDown, XF86PowerOff, XF86Sleep.
 
+.TP
+.B \-\-pass\-volume\-keys
+Allow the following keys to be used while the screen is locked by passing them through:
+XF86AudioMute, XF86AudioLowerVolume, XF86AudioRaiseVolume.
+
 .TP
 .B \-\-insidevercolor=rrggbbaa
 Sets the interior circle color while the password is being verified.

i3lock.c

@@ -236,6 +236,7 @@ bool skip_repeated_empty_password = false;
 bool pass_media_keys = false;
 bool pass_screen_keys = false;
 bool pass_power_keys = false;
+bool pass_volume_keys = false;
 
 // for the rendering thread, so we can clean it up
 pthread_t draw_thread;
@@ -700,6 +701,17 @@ static void handle_key_press(xcb_key_press_event_t *event) {
         }
     }
 
+    // volume keys
+    if (pass_volume_keys) {
+        switch(ksym) {
+            case XKB_KEY_XF86AudioMute:
+            case XKB_KEY_XF86AudioLowerVolume:
+            case XKB_KEY_XF86AudioRaiseVolume:
+                xcb_send_event(conn, true, screen->root, XCB_EVENT_MASK_BUTTON_PRESS, (char *)event);
+                return;
+        }
+    }
+
     // return/enter/etc
     switch (ksym) {
         case XKB_KEY_j:
@@ -1467,6 +1479,7 @@ int main(int argc, char *argv[]) {
         {"pass-media-keys", no_argument, NULL, 601},
         {"pass-screen-keys", no_argument, NULL, 602},
         {"pass-power-keys", no_argument, NULL, 603},
+        {"pass-volume-keys", no_argument, NULL, 604},
 
         // bar indicator stuff
         {"bar-indicator", no_argument, NULL, 700},
@@ -1943,6 +1956,9 @@ int main(int argc, char *argv[]) {
 			case 603:
 				pass_power_keys = true;
 				break;
+			case 604:
+				pass_volume_keys = true;
+				break;
 
 			// Bar indicator
             case 700: