Always retrieve device serial

This allows to execute all adb commands with the specific -s parameter,
even if it is not provided by the user.

In practice, calling adb without -s works if there is exactly one device
connected. But some adb commands (for example "adb push" on drag & drop)
could be executed after another device is connected, so the actual
device serial must be known.

app/src/scrcpy.c

@@ -394,8 +394,11 @@ scrcpy(struct scrcpy_options *options) {
     // It is necessarily initialized here, since the device is connected
     struct sc_server_info *info = &s->server.info;
 
+    const char *serial = s->server.params.serial;
+    assert(serial);
+
     if (options->display && options->control) {
-        if (!file_handler_init(&s->file_handler, options->serial,
+        if (!file_handler_init(&s->file_handler, serial,
                                options->push_target)) {
             goto end;
         }
@@ -516,21 +519,7 @@ scrcpy(struct scrcpy_options *options) {
 #ifdef HAVE_AOA_HID
             bool aoa_hid_ok = false;
 
-            char *serialno = NULL;
-
-            const char *serial = options->serial;
-            if (!serial) {
-                serialno = adb_get_serialno();
-                if (!serialno) {
-                    LOGE("Could not get device serial");
-                    goto aoa_hid_end;
-                }
-                serial = serialno;
-                LOGI("Device serial: %s", serial);
-            }
-
             bool ok = sc_aoa_init(&s->aoa, serial);
-            free(serialno);
             if (!ok) {
                 goto aoa_hid_end;
             }

app/src/server.c

@@ -422,12 +422,36 @@ sc_server_on_terminated(void *userdata) {
     LOGD("Server terminated");
 }
 
+static bool
+sc_server_fill_serial(struct sc_server *server) {
+    // Retrieve the actual device immediately if not provided, so that all
+    // future adb commands are executed for this specific device, even if other
+    // devices are connected afterwards (without "more than one
+    // device/emulator" error)
+    if (!server->params.serial) {
+        // The serial is owned by sc_server_params, and will be freed on destroy
+        server->params.serial = adb_get_serialno();
+        if (!server->params.serial) {
+            LOGE("Could not get device serial");
+            return false;
+        }
+    }
+
+    return true;
+}
+
 static int
 run_server(void *data) {
     struct sc_server *server = data;
 
+    if (!sc_server_fill_serial(server)) {
+        goto error_connection_failed;
+    }
+
     const struct sc_server_params *params = &server->params;
 
+    LOGD("Device serial: %s", params->serial);
+
     bool ok = push_server(&server->intr, params->serial);
     if (!ok) {
         goto error_connection_failed;