From: Antonio Ospite <ao2@ao2.it>
Date: Wed, 10 Jun 2015 09:13:04 +0000 (+0200)
Subject: Misc libusb cleanups
X-Git-Url: https://git.ao2.it/visomat-utils.git/commitdiff_plain/f7a9b92e7107a03a92e64a7091f0dea908210cda?ds=inline

Misc libusb cleanups

Use symbolic constants, check return values, auto detach the kernel
driver, release the interface.
---

diff --git a/src/visomat-data-downloader.c b/src/visomat-data-downloader.c
index a91ee43..8cb99e2 100644
--- a/src/visomat-data-downloader.c
+++ b/src/visomat-data-downloader.c
@@ -25,15 +25,16 @@
 #include <unistd.h>
 #include <libusb.h>
 
+#define VISOMAT_DEVICE_VID    0x1247
+#define VISOMAT_DEVICE_PID    0x00f8
+#define VISOMAT_CONFIGURATION 1
+#define VISOMAT_INTERFACE     1
+#define VISOMAT_EP_IN         0x82
+#define VISOMAT_EP_OUT        0x03
+
 #define STX 0x02
 #define ETX 0x03
 
-#define DEVICE_VID 0x1247
-#define DEVICE_PID 0x00f8
-
-#define EP_IN 0x82
-#define EP_OUT 0x03
-
 #define BASE_YEAR 2000
 
 typedef enum {
@@ -224,7 +225,7 @@ static int send_command(libusb_device_handle *dev, visomat_command cmd)
 	request[4] = ETX;
 
 	transferred = 0;
-	ret = libusb_bulk_transfer(dev, EP_OUT, request, sizeof(request), &transferred, 0);
+	ret = libusb_bulk_transfer(dev, VISOMAT_EP_OUT, request, sizeof(request), &transferred, 0);
 	if (ret != 0 || transferred != sizeof(request)) {
 		fprintf(stderr, "Error: sending request: %d (%s)\ttransferred: %d (expected %zu)\n",
 			ret, libusb_error_name(ret), transferred, sizeof(request));
@@ -247,7 +248,7 @@ static int get_response(libusb_device_handle *dev,
 		unsigned int j;
 
 		transferred = 0;
-		ret = libusb_bulk_transfer(dev, EP_IN, response, sizeof(response), &transferred, 5000);
+		ret = libusb_bulk_transfer(dev, VISOMAT_EP_IN, response, sizeof(response), &transferred, 5000);
 		if (ret != 0) {
 			fprintf(stderr, "Error getting response: %d (%s)\ttransferred: %d (expected %zu)\n",
 				ret, libusb_error_name(ret), transferred, sizeof(response));
@@ -316,29 +317,54 @@ int main(void)
 	int ret;
 	libusb_device_handle *dev;
 
-	libusb_init(NULL);
+	ret = libusb_init(NULL);
+	if (ret < 0) {
+		fprintf(stderr, "error (%d): cannot initialize libusb.\n", ret);
+		goto out;
+	}
+
 	libusb_set_debug(NULL, LIBUSB_LOG_LEVEL_INFO);
 
-	dev = libusb_open_device_with_vid_pid(NULL, DEVICE_VID, DEVICE_PID);
+	dev = libusb_open_device_with_vid_pid(NULL,
+					      VISOMAT_DEVICE_VID,
+					      VISOMAT_DEVICE_PID);
 	if (dev == NULL) {
-		fprintf(stderr, "Couldn't open device.\n");
-		ret = -ENODEV;
+		fprintf(stderr, "error (%d): cannot open device.\n", errno);
+		ret = -errno;
 		goto out_libusb_exit;
 	}
 
-	libusb_set_configuration(dev, 1);
-	libusb_detach_kernel_driver(dev, 1);
-	libusb_claim_interface(dev, 1);
+	ret = libusb_set_configuration(dev, VISOMAT_CONFIGURATION);
+	if (ret < 0) {
+		fprintf(stderr, "error (%d): cannot set configuration %d.\n",
+			ret, 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);
+		goto out_libusb_close;
+	}
 
 	ret = visomat_get_datetime(dev);
 	if (ret < 0)
-		goto out;
+		goto out_libusb_release_interface;
 
 	ret = visomat_dump_eeprom(dev, 0x01 | 0x02);
+	if (ret < 0)
+		goto out_libusb_release_interface;
 
-out:
+out_libusb_release_interface:
+	libusb_release_interface(dev, VISOMAT_INTERFACE);
+out_libusb_close:
 	libusb_close(dev);
+	dev = NULL;
 out_libusb_exit:
 	libusb_exit(NULL);
+out:
 	return ret;
 }