kinect_upload_fw: make libusb initialization more robust

Check the return values of all the libusb functions.

Also return more sensible values when ret is not immediately useful.

diff --git a/kinect_upload_fw/kinect_upload_fw.c b/kinect_upload_fw/kinect_upload_fw.c
index 223595d..cf65b5b 100644 (file)
--- a/kinect_upload_fw/kinect_upload_fw.c
+++ b/kinect_upload_fw/kinect_upload_fw.c
@@ -259,38 +259,79 @@ int main(int argc, char *argv[]) {
                return -errno;
        }
 
-       libusb_init(NULL);
+       ret = libusb_init(NULL);
+       if (ret < 0) {
+               fprintf(stderr, "libusb_init failed: %s\n",
+                       libusb_error_name(ret));
+               goto out;
+       }
+
        libusb_set_debug(NULL, 3);
 
        dev = libusb_open_device_with_vid_pid(NULL, KINECT_AUDIO_VID, KINECT_AUDIO_PID);
        if (dev == NULL) {
-               fprintf(stderr, "Couldn't open device.\n");
-               ret = -ENODEV;
-               goto fail_libusb_open;
+               fprintf(stderr, "libusb_open failed: %s\n", strerror(errno));
+               ret = -errno;
+               goto out_libusb_exit;
        }
 
        int current_configuration = -1;
-       libusb_get_configuration(dev, &current_configuration);
-       if (current_configuration != KINECT_AUDIO_CONFIGURATION)
-               libusb_set_configuration(dev, KINECT_AUDIO_CONFIGURATION);
+       ret = libusb_get_configuration(dev, &current_configuration);
+       if (ret < 0) {
+               fprintf(stderr, "libusb_get_configuration failed: %s\n",
+                       libusb_error_name(ret));
+               goto out_libusb_close;
+       }
+
+       if (current_configuration != KINECT_AUDIO_CONFIGURATION) {
+               ret = libusb_set_configuration(dev, KINECT_AUDIO_CONFIGURATION);
+               if (ret < 0) {
+                       fprintf(stderr, "libusb_set_configuration failed: %s\n",
+                               libusb_error_name(ret));
+                       fprintf(stderr, "Cannot set configuration %d\n",
+                               KINECT_AUDIO_CONFIGURATION);
+                       goto out_libusb_close;
+               }
+       }
 
-       libusb_claim_interface(dev, KINECT_AUDIO_INTERFACE);
+       ret = libusb_claim_interface(dev, KINECT_AUDIO_INTERFACE);
+       if (ret < 0) {
+               fprintf(stderr, "libusb_claim_interface failed: %s\n",
+                       libusb_error_name(ret));
+               fprintf(stderr, "Cannot claim interface %d\n",
+                       KINECT_AUDIO_INTERFACE);
+               goto out_libusb_close;
+       }
 
+       /* 
+        * Checking that the configuration has not changed, as suggested in
+        * http://libusb.sourceforge.net/api-1.0/caveats.html
+        */
        current_configuration = -1;
-       libusb_get_configuration(dev, &current_configuration);
+       ret = libusb_get_configuration(dev, &current_configuration);
+       if (ret < 0) {
+               fprintf(stderr, "libusb_get_configuration after claim failed: %s\n",
+                       libusb_error_name(ret));
+               goto out_libusb_release_interface;
+       }
+
        if (current_configuration != KINECT_AUDIO_CONFIGURATION) {
-               ret = -ENODEV;
-               goto cleanup;
+               fprintf(stderr, "libusb configuration changed (expected: %d, current: %d)\n",
+                       KINECT_AUDIO_CONFIGURATION, current_configuration);
+               ret = -EINVAL;
+               goto out_libusb_release_interface;
        }
 
        ret = upload_firmware(fw);
        // Now the device reenumerates.
 
-cleanup:
+out_libusb_release_interface:
        libusb_release_interface(dev, KINECT_AUDIO_INTERFACE);
+out_libusb_close:
        libusb_close(dev);
-fail_libusb_open:
+out_libusb_exit:
        libusb_exit(NULL);
+out:
        fclose(fw);
        return ret;
 }