Do not report error on device disconnected

A device disconnection (when the adb connection is closed) makes the
read() on the "receiver" socket fail.

Since commit 063a8339ed, this is reported
as an error. As a consequence, scrcpy fails with:

    ERROR: Controller error

instead of:

    WARN: Device disconnected

To fix the issue, report a device disconnection in that case.

PR #5044 <https://github.com/Genymobile/scrcpy/pull/5044>

app/src/controller.c

@@ -7,12 +7,13 @@
 #define SC_CONTROL_MSG_QUEUE_MAX 64
 
 static void
-sc_controller_receiver_on_error(struct sc_receiver *receiver, void *userdata) {
+sc_controller_receiver_on_ended(struct sc_receiver *receiver, bool error,
+                                void *userdata) {
     (void) receiver;
 
     struct sc_controller *controller = userdata;
     // Forward the event to the controller listener
-    controller->cbs->on_error(controller, controller->cbs_userdata);
+    controller->cbs->on_ended(controller, error, controller->cbs_userdata);
 }
 
 bool
@@ -27,7 +28,7 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
     }
 
     static const struct sc_receiver_callbacks receiver_cbs = {
-        .on_error = sc_controller_receiver_on_error,
+        .on_ended = sc_controller_receiver_on_ended,
     };
 
     ok = sc_receiver_init(&controller->receiver, control_socket, &receiver_cbs,
@@ -55,7 +56,7 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
     controller->control_socket = control_socket;
     controller->stopped = false;
 
-    assert(cbs && cbs->on_error);
+    assert(cbs && cbs->on_ended);
     controller->cbs = cbs;
     controller->cbs_userdata = cbs_userdata;
 
@@ -110,21 +111,30 @@ sc_controller_push_msg(struct sc_controller *controller,
 
 static bool
 process_msg(struct sc_controller *controller,
-            const struct sc_control_msg *msg) {
+            const struct sc_control_msg *msg, bool *eos) {
     static uint8_t serialized_msg[SC_CONTROL_MSG_MAX_SIZE];
     size_t length = sc_control_msg_serialize(msg, serialized_msg);
     if (!length) {
+        *eos = false;
         return false;
     }
+
     ssize_t w =
         net_send_all(controller->control_socket, serialized_msg, length);
-    return (size_t) w == length;
+    if ((size_t) w != length) {
+        *eos = true;
+        return false;
+    }
+
+    return true;
 }
 
 static int
 run_controller(void *data) {
     struct sc_controller *controller = data;
 
+    bool error = false;
+
     for (;;) {
         sc_mutex_lock(&controller->mutex);
         while (!controller->stopped
@@ -134,6 +144,7 @@ run_controller(void *data) {
         if (controller->stopped) {
             // stop immediately, do not process further msgs
             sc_mutex_unlock(&controller->mutex);
+            LOGD("Controller stopped");
             break;
         }
 
@@ -141,20 +152,21 @@ run_controller(void *data) {
         struct sc_control_msg msg = sc_vecdeque_pop(&controller->queue);
         sc_mutex_unlock(&controller->mutex);
 
-        bool ok = process_msg(controller, &msg);
+        bool eos;
+        bool ok = process_msg(controller, &msg, &eos);
         sc_control_msg_destroy(&msg);
         if (!ok) {
-            LOGD("Could not write msg to socket");
-            goto error;
+            if (eos) {
+                LOGD("Controller stopped (socket closed)");
+            } // else error already logged
+            error = !eos;
+            break;
         }
     }
 
+    controller->cbs->on_ended(controller, error, controller->cbs_userdata);
+
     return 0;
-
-error:
-    controller->cbs->on_error(controller, controller->cbs_userdata);
-
-    return 1; // ignored
 }
 
 bool

app/src/controller.h

@@ -28,7 +28,8 @@ struct sc_controller {
 };
 
 struct sc_controller_callbacks {
-    void (*on_error)(struct sc_controller *controller, void *userdata);
+    void (*on_ended)(struct sc_controller *controller, bool error,
+                     void *userdata);
 };
 
 bool

app/src/receiver.c

@@ -21,7 +21,7 @@ sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
     receiver->acksync = NULL;
     receiver->uhid_devices = NULL;
 
-    assert(cbs && cbs->on_error);
+    assert(cbs && cbs->on_ended);
     receiver->cbs = cbs;
     receiver->cbs_userdata = cbs_userdata;
 
@@ -134,12 +134,15 @@ run_receiver(void *data) {
     static uint8_t buf[DEVICE_MSG_MAX_SIZE];
     size_t head = 0;
 
+    bool error = false;
+
     for (;;) {
         assert(head < DEVICE_MSG_MAX_SIZE);
         ssize_t r = net_recv(receiver->control_socket, buf + head,
                              DEVICE_MSG_MAX_SIZE - head);
         if (r <= 0) {
             LOGD("Receiver stopped");
+            // device disconnected: keep error=false
             break;
         }
 
@@ -147,6 +150,7 @@ run_receiver(void *data) {
         ssize_t consumed = process_msgs(receiver, buf, head);
         if (consumed == -1) {
             // an error occurred
+            error = true;
             break;
         }
 
@@ -157,7 +161,7 @@ run_receiver(void *data) {
         }
     }
 
-    receiver->cbs->on_error(receiver, receiver->cbs_userdata);
+    receiver->cbs->on_ended(receiver, error, receiver->cbs_userdata);
 
     return 0;
 }

app/src/receiver.h

@@ -25,7 +25,7 @@ struct sc_receiver {
 };
 
 struct sc_receiver_callbacks {
-    void (*on_error)(struct sc_receiver *receiver, void *userdata);
+    void (*on_ended)(struct sc_receiver *receiver, bool error, void *userdata);
 };
 
 bool

app/src/scrcpy.c

@@ -269,13 +269,18 @@ sc_audio_demuxer_on_ended(struct sc_demuxer *demuxer,
 }
 
 static void
-sc_controller_on_error(struct sc_controller *controller, void *userdata) {
+sc_controller_on_ended(struct sc_controller *controller, bool error,
+                       void *userdata) {
     // Note: this function may be called twice, once from the controller thread
     // and once from the receiver thread
     (void) controller;
     (void) userdata;
 
-    PUSH_EVENT(SC_EVENT_CONTROLLER_ERROR);
+    if (error) {
+        PUSH_EVENT(SC_EVENT_CONTROLLER_ERROR);
+    } else {
+        PUSH_EVENT(SC_EVENT_DEVICE_DISCONNECTED);
+    }
 }
 
 static void
@@ -567,7 +572,7 @@ scrcpy(struct scrcpy_options *options) {
 
     if (options->control) {
         static const struct sc_controller_callbacks controller_cbs = {
-            .on_error = sc_controller_on_error,
+            .on_ended = sc_controller_on_ended,
         };
 
         if (!sc_controller_init(&s->controller, s->server.control_socket,