Added a new WebcamChanged bus signal that will let clients know when …

…a new webcam is connected/a webcam is disconnected from system.

README.md

@@ -89,7 +89,7 @@ Last line will smoothly change current backlight on every internal/external scre
 
 Please note that for internal laptop screen, serialNumber must be your backlight kernel interface (eg: intel_backlight) or an empty string (to forcefully use first udev backlight subsystem matching device).  
 
-A "version" bus property is exported too. It will return a "s" of clightd version.  
+### Methods
 
 *Smooth struct* here means:  
 * b -> isSmooth (true for smooth change)
@@ -112,6 +112,19 @@ A "version" bus property is exported too. It will return a "s" of clightd versio
 | setdpms_timeouts | ssiii | <ul><li>env DISPLAY</li><li>env XAUTHORITY</li><li>New dpms timeouts</li></ul> | iii | New dpms timeouts | ✔ | ✔ |
 | getidletime | ss | <ul><li>env DISPLAY</li><li>env XAUTHORITY</li></ul> | i | Current idle time in ms | | ✔ |
 
+### Properties
+
+| Prop | OUT | OUT values |
+|-|:-:|-|
+| version | s | Clightd version |
+
+### Signals
+
+| Sig | OUT | OUT values |
+|-|:-:|-|
+| WebcamChanged | ss | <ul><li>Webcam's devpath</li><li>Action string, as received from udev. Eg: "add", "remove".</li></ul> |
+
+
 ## Ddcutil support
 Clightd uses [ddcutil](https://github.com/rockowitz/ddcutil) C api to set external monitor brightness and thus supporting desktop PCs too.  
 

TODO.md

@@ -1,4 +1,7 @@
 ## 2.4
+- [x] Add WebcamChanged signal that will be sent when a new webcam is connected/a webcam is disconnected
+
+## 2.5
 - [ ] Add gamma (and dpms + idle) support on wayland (wlroots)
 https://github.com/swaywm/wlroots/blob/master/examples/gamma-control.c
 https://github.com/swaywm/wlroots/blob/master/examples/idle.c

inc/udev.h

@@ -2,5 +2,9 @@
 
 extern struct udev *udev;
 
+#ifndef DISABLE_FRAME_CAPTURES
+int init_udev_monitor(const char *subsystem);
+void receive_udev_device(struct udev_device **dev);
+#endif
 void get_udev_device(const char *interface, const char *subsystem,
                      sd_bus_error **ret_error, struct udev_device **dev);

src/clightd.c

@@ -45,6 +45,9 @@ enum poll_idx {
     BRIGHT_SMOOTH,
 #ifdef GAMMA_PRESENT
     GAMMA_SMOOTH,
+#endif
+#ifndef DISABLE_FRAME_CAPTURES
+    UDEV_MON,
 #endif
     POLL_SIZE };
 enum quit_codes { LEAVE_W_ERR = -1, SIGNAL_RCV = 1 };
@@ -74,6 +77,7 @@ static const sd_bus_vtable clightd_vtable[] = {
 #ifndef DISABLE_FRAME_CAPTURES
     SD_BUS_METHOD("captureframes", "si", "ad", method_captureframes, SD_BUS_VTABLE_UNPRIVILEGED),
     SD_BUS_METHOD("iswebcamavailable", "", "b", method_iswebcamavailable, SD_BUS_VTABLE_UNPRIVILEGED),
+    SD_BUS_SIGNAL("WebcamChanged", "ss", 0),
 #endif
 #ifdef DPMS_PRESENT
     SD_BUS_METHOD("getdpms", "ss", "i", method_getdpms, SD_BUS_VTABLE_UNPRIVILEGED),
@@ -151,6 +155,12 @@ static void set_pollfd(void) {
     };
     set_gamma_smooth_fd(gamma_smooth_fd);
 #endif
+#ifndef DISABLE_FRAME_CAPTURES
+    main_p[UDEV_MON] = (struct pollfd) {
+        .fd = init_udev_monitor("video4linux"),
+        .events = POLLIN,
+    };
+#endif
 }
 
 /*
@@ -181,6 +191,17 @@ static void main_poll(void) {
                 case GAMMA_SMOOTH:
                     gamma_smooth_cb();
                     break;
+#endif
+#ifndef DISABLE_FRAME_CAPTURES
+                case UDEV_MON: {
+                    struct udev_device *dev = NULL;
+                    receive_udev_device(&dev);
+                    if (dev) {
+                        sd_bus_emit_signal(bus, object_path, bus_interface, "WebcamChanged", "ss", udev_device_get_devnode(dev), udev_device_get_action(dev));
+                        udev_device_unref(dev);
+                    }
+                    break;
+                }
 #endif
                 }
                 r--;

src/udev.c

@@ -2,6 +2,21 @@
 
 static void get_first_matching_device(struct udev_device **dev, const char *subsystem);
 
+#ifndef DISABLE_FRAME_CAPTURES
+static struct udev_monitor *mon;
+
+int init_udev_monitor(const char *subsystem) {
+    mon = udev_monitor_new_from_netlink(udev, "udev");
+    udev_monitor_filter_add_match_subsystem_devtype(mon, subsystem, NULL);
+    udev_monitor_enable_receiving(mon);
+    return udev_monitor_get_fd(mon);
+}
+
+void receive_udev_device(struct udev_device **dev) {
+    *dev = udev_monitor_receive_device(mon);
+}
+#endif
+
 /**
  * Set dev to first device in subsystem
  */