X-Git-Url: https://git.ao2.it/visomat-utils.git/blobdiff_plain/91d0c4148bdb1fca33062b80b669e3c9e00c8030..6d26d073abb2eed23a21d87058b8d6eb0e8d2112:/src/visomat-data-downloader.c

diff --git a/src/visomat-data-downloader.c b/src/visomat-data-downloader.c
index a91ee43..c2b8590 100644
--- a/src/visomat-data-downloader.c
+++ b/src/visomat-data-downloader.c
@@ -21,19 +21,21 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #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 {
@@ -117,7 +119,7 @@ static void print_record_csv_compat(struct datetime *d, struct pressure *p)
 	printf("\n");
 }
 
-/* TODO separate better decoding data from printing it */
+/* TODO: it would be better to separate decoding data from printing it */
 static int decode_eeprom(unsigned char *buffer,
 			 unsigned int len,
 			 unsigned int user_mask)
@@ -224,7 +226,7 @@ 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 +249,7 @@ 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));
@@ -315,30 +317,89 @@ int main(void)
 {
 	int ret;
 	libusb_device_handle *dev;
+	int current_configuration;
+
+	ret = libusb_init(NULL);
+	if (ret < 0) {
+		fprintf(stderr, "libusb_init failed: %s\n",
+			libusb_error_name(ret));
+		goto out;
+	}
 
-	libusb_init(NULL);
 	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, "libusb_open failed: %s\n", strerror(errno));
+		ret = -errno;
 		goto out_libusb_exit;
 	}
 
-	libusb_set_configuration(dev, 1);
-	libusb_detach_kernel_driver(dev, 1);
-	libusb_claim_interface(dev, 1);
+	current_configuration = -1;
+	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 != 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, "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;
+		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;
 }