Split USB initialization and connection

This will allow to execute other USB calls (retrieving the device list
for example) before connecting to the selected device.

PR #2974 <https://github.com/Genymobile/scrcpy/pull/2974>

app/src/scrcpy.c

@@ -424,9 +424,17 @@ scrcpy(struct scrcpy_options *options) {
                 goto end;
             }
 
-            ok = sc_usb_init(&s->usb, serial);
+            ok = sc_usb_init(&s->usb);
             if (!ok) {
-                LOGE("Failed to initialized USB device");
+                LOGE("Failed to initialize USB");
+                sc_acksync_destroy(&s->acksync);
+                goto aoa_hid_end;
+            }
+
+            ok = sc_usb_connect(&s->usb, serial);
+            if (!ok) {
+                LOGE("Failed to connect to USB device %s", serial);
+                sc_usb_destroy(&s->usb);
                 sc_acksync_destroy(&s->acksync);
                 goto aoa_hid_end;
             }
@@ -434,6 +442,7 @@ scrcpy(struct scrcpy_options *options) {
             ok = sc_aoa_init(&s->aoa, &s->usb, &s->acksync);
             if (!ok) {
                 LOGE("Failed to enable HID over AOA");
+                sc_usb_disconnect(&s->usb);
                 sc_usb_destroy(&s->usb);
                 sc_acksync_destroy(&s->acksync);
                 goto aoa_hid_end;
@@ -461,6 +470,7 @@ scrcpy(struct scrcpy_options *options) {
 
             if (!need_aoa || !sc_aoa_start(&s->aoa)) {
                 sc_acksync_destroy(&s->acksync);
+                sc_usb_disconnect(&s->usb);
                 sc_usb_destroy(&s->usb);
                 sc_aoa_destroy(&s->aoa);
                 goto aoa_hid_end;
@@ -650,6 +660,7 @@ end:
     if (aoa_hid_initialized) {
         sc_aoa_join(&s->aoa);
         sc_aoa_destroy(&s->aoa);
+        sc_usb_disconnect(&s->usb);
         sc_usb_destroy(&s->usb);
     }
 #endif

app/src/usb/usb.c

@@ -76,18 +76,23 @@ sc_usb_open_handle(libusb_device *device) {
  }
 
 bool
-sc_usb_init(struct sc_usb *usb, const char *serial) {
-    assert(serial);
+sc_usb_init(struct sc_usb *usb) {
+    usb->handle = NULL;
+    return libusb_init(&usb->context) == LIBUSB_SUCCESS;
+}
 
-    // There is only one device, initialize the context here
-    if (libusb_init(&usb->context) != LIBUSB_SUCCESS) {
-        return false;
-    }
+void
+sc_usb_destroy(struct sc_usb *usb) {
+    libusb_exit(usb->context);
+}
+
+bool
+sc_usb_connect(struct sc_usb *usb, const char *serial) {
+    assert(serial);
 
     libusb_device *device = sc_usb_find_device(usb, serial);
     if (!device) {
         LOGW("USB device %s not found", serial);
-        libusb_exit(usb->context);
         return false;
     }
 
@@ -95,7 +100,6 @@ sc_usb_init(struct sc_usb *usb, const char *serial) {
     libusb_unref_device(device);
     if (!usb->handle) {
         LOGW("Could not open USB device %s", serial);
-        libusb_exit(usb->context);
         return false;
     }
 
@@ -103,7 +107,6 @@ sc_usb_init(struct sc_usb *usb, const char *serial) {
 }
 
 void
-sc_usb_destroy(struct sc_usb *usb) {
+sc_usb_disconnect(struct sc_usb *usb) {
     libusb_close(usb->handle);
-    libusb_exit(usb->context);
 }

app/src/usb/usb.h

@@ -12,9 +12,15 @@ struct sc_usb {
 };
 
 bool
-sc_usb_init(struct sc_usb *usb, const char *serial);
+sc_usb_init(struct sc_usb *usb);
 
 void
 sc_usb_destroy(struct sc_usb *usb);
 
+bool
+sc_usb_connect(struct sc_usb *usb, const char *serial);
+
+void
+sc_usb_disconnect(struct sc_usb *usb);
+
 #endif