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 (file)
--- 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;
 }