X-Git-Url: https://git.ao2.it/visomat-utils.git/blobdiff_plain/f7a9b92e7107a03a92e64a7091f0dea908210cda..ba30def0cce654c843873f8653d1f3a5338e8410:/src/visomat-data-downloader.c

diff --git a/src/visomat-data-downloader.c b/src/visomat-data-downloader.c
index 8cb99e2..818473f 100644
--- a/src/visomat-data-downloader.c
+++ b/src/visomat-data-downloader.c
@@ -21,6 +21,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <unistd.h>
 #include <libusb.h>
@@ -316,10 +317,11 @@ int main(void)
 {
 	int ret;
 	libusb_device_handle *dev;
+	int current_configuration;
 
 	ret = libusb_init(NULL);
 	if (ret < 0) {
-		fprintf(stderr, "error (%d): cannot initialize libusb.\n", ret);
+		fprintf(stderr, "libusb_init failed: %s\n", libusb_error_name(ret));
 		goto out;
 	}
 
@@ -329,27 +331,59 @@ int main(void)
 					      VISOMAT_DEVICE_VID,
 					      VISOMAT_DEVICE_PID);
 	if (dev == NULL) {
-		fprintf(stderr, "error (%d): cannot open device.\n", errno);
+		fprintf(stderr, "libusb_open failed: %s\n", strerror(errno));
 		ret = -errno;
 		goto out_libusb_exit;
 	}
 
-	ret = libusb_set_configuration(dev, VISOMAT_CONFIGURATION);
+	current_configuration = -1;
+	ret = libusb_get_configuration(dev, &current_configuration);
 	if (ret < 0) {
-		fprintf(stderr, "error (%d): cannot set configuration %d.\n",
-			ret, VISOMAT_CONFIGURATION);
+		fprintf(stderr, "libusb_get_configuration failed: %s\n",
+			libusb_error_name(ret));
 		goto out_libusb_close;
 	}
 
+	if (current_configuration != VISOMAT_CONFIGURATION) {
+		ret = libusb_set_configuration(dev, VISOMAT_CONFIGURATION);
+		if (ret < 0) {
+			fprintf(stderr, "libusb_set_configuration failed: %s\n",
+				libusb_error_name(ret));
+			fprintf(stderr, "Cannot set configuration %hhu\n",
+				VISOMAT_CONFIGURATION);
+			goto out_libusb_close;
+		}
+	}
+
 	libusb_set_auto_detach_kernel_driver(dev, 1);
 
 	ret = libusb_claim_interface(dev, VISOMAT_INTERFACE);
 	if (ret < 0) {
-		fprintf(stderr, "error (%d): cannot claim interface %d.\n",
-			ret, VISOMAT_INTERFACE);
+		fprintf(stderr, "libusb_claim_interface failed: %s\n",
+			libusb_error_name(ret));
+		fprintf(stderr, "Cannot claim interface %hhu\n",
+			VISOMAT_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;
+	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 != VISOMAT_CONFIGURATION) {
+		fprintf(stderr, "libusb configuration changed (expected: %hhu, current: %hhu\n",
+			VISOMAT_CONFIGURATION, current_configuration);
+		ret = -EINVAL;
+		goto out_libusb_release_interface;
+	}
+
 	ret = visomat_get_datetime(dev);
 	if (ret < 0)
 		goto out_libusb_release_interface;