Fetch configurations by index (not value)

Otherwise there is no way to know which values to look for.

5 files changed, 74 insertions, 57 deletions

diff --git a/libusb/core.c b/libusb/core.c
index 43491ad..d94d7b8 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -325,6 +325,7 @@ int usbi_sanitize_device(struct libusb_device *dev)
 		return LIBUSB_ERROR_IO;
 	}
 
+	dev->num_configurations = num_configurations;
 	return 0;
 }
 
diff --git a/libusb/descriptor.c b/libusb/descriptor.c
index e07711a..8814ced 100644
--- a/libusb/descriptor.c
+++ b/libusb/descriptor.c
@@ -432,6 +432,7 @@ API_EXPORTED int libusb_get_device_descriptor(libusb_device *dev,
 	unsigned char raw_desc[DEVICE_DESC_LENGTH];
 	int r;
 
+	usbi_dbg("");
 	r = usbi_backend->get_device_descriptor(dev, raw_desc);
 	if (r < 0)
 		return r;
@@ -460,6 +461,7 @@ struct libusb_config_descriptor *libusb_get_active_config_descriptor(
 	unsigned char *buf = NULL;
 	int r;
 
+	usbi_dbg("");
 	if (!config)
 		return NULL;
 
@@ -467,7 +469,7 @@ struct libusb_config_descriptor *libusb_get_active_config_descriptor(
 	if (r < 0)
 		goto err;
 
-	usbi_parse_descriptor(tmp, "bbw", &config);
+	usbi_parse_descriptor(tmp, "bbw", config);
 	buf = malloc(config->wTotalLength);
 	if (!buf)
 		goto err;
@@ -495,40 +497,45 @@ err:
 }
 
 /** \ingroup desc
- * Get the USB configuration descriptor for the currently active configuration.
+ * Get a USB configuration descriptor based on its index.
  * This is a non-blocking function which does not involve any requests being
  * sent to the device.
  *
  * \param dev a device
- * \param bConfigurationValue the bConfigurationValue of the configuration
- * you wish to retreive
+ * \param config_index the index of the configuration you wish to retrieve
  * \returns the USB configuration descriptor which must be freed with
  * libusb_free_config_descriptor() when done
  * \returns NULL on error
  * \see libusb_get_active_config_descriptor()
+ * \see libusb_get_config_descriptor_by_value()
  */
 API_EXPORTED struct libusb_config_descriptor *libusb_get_config_descriptor(
-	libusb_device *dev, uint8_t bConfigurationValue)
+	libusb_device *dev, uint8_t config_index)
 {
-	struct libusb_config_descriptor *config = malloc(sizeof(*config));
+	struct libusb_config_descriptor *config;
 	unsigned char tmp[8];
 	unsigned char *buf = NULL;
 	int r;
 
+	usbi_dbg("index %d", config_index);
+	if (config_index >= dev->num_configurations)
+		return NULL;
+
+	config = malloc(sizeof(*config));
 	if (!config)
 		return NULL;
 
-	r = usbi_backend->get_config_descriptor(dev, bConfigurationValue, tmp,
+	r = usbi_backend->get_config_descriptor(dev, config_index, tmp,
 		sizeof(tmp));
 	if (r < 0)
 		goto err;
 
-	usbi_parse_descriptor(tmp, "bbw", &config);
+	usbi_parse_descriptor(tmp, "bbw", config);
 	buf = malloc(config->wTotalLength);
 	if (!buf)
 		goto err;
 
-	r = usbi_backend->get_config_descriptor(dev, bConfigurationValue, buf,
+	r = usbi_backend->get_config_descriptor(dev, config_index, buf,
 		config->wTotalLength);
 	if (r < 0)
 		goto err;
@@ -551,6 +558,46 @@ err:
 }
 
 /** \ingroup desc
+ * Get a USB configuration descriptor with a specific bConfigurationValue.
+ * This is a non-blocking function which does not involve any requests being
+ * sent to the device.
+ *
+ * \param dev a device
+ * \param bConfigurationValue the bConfigurationValue of the configuration you
+ * wish to retrieve
+ * \returns the USB configuration descriptor which must be freed with
+ * libusb_free_config_descriptor() when done
+ * \returns NULL on error
+ * \see libusb_get_active_config_descriptor()
+ * \see libusb_get_config_descriptor()
+ */
+API_EXPORTED
+struct libusb_config_descriptor *libusb_get_config_descriptor_by_value(
+	libusb_device *dev, uint8_t bConfigurationValue)
+{
+	int i;
+	int r;
+	int found = -1;
+
+	usbi_dbg("value %d", bConfigurationValue);
+	for (i = 0; i < dev->num_configurations; i++) {
+		unsigned char tmp[6];
+		r = usbi_backend->get_config_descriptor(dev, i, tmp, sizeof(tmp));
+		if (r < 0)
+			return NULL;
+		if (tmp[5] == bConfigurationValue) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found)
+		return NULL;
+	else
+		return libusb_get_config_descriptor(dev, i);
+}
+
+/** \ingroup desc
  * Free a configuration descriptor obtained from
  * libusb_get_active_config_descriptor() or libusb_get_config_descriptor().
  * It is safe to call this function with a NULL config parameter, in which
diff --git a/libusb/libusb.h b/libusb/libusb.h
index 62ed0ea..f946a27 100644
--- a/libusb/libusb.h
+++ b/libusb/libusb.h
@@ -670,7 +670,9 @@ int libusb_get_device_descriptor(libusb_device *dev,
 struct libusb_config_descriptor *libusb_get_active_config_descriptor(
 	libusb_device *dev);
 struct libusb_config_descriptor *libusb_get_config_descriptor(
-	libusb_device *dev, uint8_t config);
+	libusb_device *dev, uint8_t config_index);
+struct libusb_config_descriptor *libusb_get_config_descriptor_by_value(
+	libusb_device *dev, uint8_t bConfigurationValue);
 void libusb_free_config_descriptor(struct libusb_config_descriptor *config);
 uint8_t libusb_get_bus_number(libusb_device *dev);
 uint8_t libusb_get_device_address(libusb_device *dev);
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index e596b86..c807903 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -150,6 +150,7 @@ struct libusb_device {
 
 	uint8_t bus_number;
 	uint8_t device_address;
+	uint8_t num_configurations;
 
 	struct list_head list;
 	unsigned long session_data;
@@ -273,8 +274,8 @@ struct usbi_os_backend {
 		unsigned char *buffer);
 	int (*get_active_config_descriptor)(struct libusb_device *device,
 		unsigned char *buffer, size_t len);
-	int (*get_config_descriptor)(struct libusb_device *device, uint8_t config,
-		unsigned char *buffer, size_t len);
+	int (*get_config_descriptor)(struct libusb_device *device,
+		uint8_t config_index, unsigned char *buffer, size_t len);
 
 	int (*set_configuration)(struct libusb_device_handle *handle, int config);
 
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 6bebc06..957900a 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -301,49 +301,22 @@ static int op_get_active_config_descriptor(struct libusb_device *dev,
 /* takes a usbfs fd, attempts to find the requested config and copy a certain
  * amount of it into an output buffer. a bConfigurationValue of -1 indicates
  * that the first config should be retreived. */
-static int get_config_descriptor(int fd, int bConfigurationValue,
+static int get_config_descriptor(int fd, uint8_t config_index,
 	unsigned char *buffer, size_t len)
 {
 	unsigned char tmp[8];
-	uint8_t num_configurations;
 	off_t off;
 	ssize_t r;
 
-	if (bConfigurationValue == -1) {
-		/* read first configuration */
-		off = lseek(fd, DEVICE_DESC_LENGTH, SEEK_SET);
-		if (off < 0) {
-			usbi_err("seek failed, ret=%d errno=%d", off, errno);
-			return LIBUSB_ERROR_IO;
-		}
-		r = read(fd, buffer, len);
-		if (r < 0) {
-			usbi_err("read failed ret=%d errno=%d", r, errno);
-			return LIBUSB_ERROR_IO;
-		} else if (r < len) {
-			usbi_err("short output read %d/%d", r, len);
-			return LIBUSB_ERROR_IO;
-		}
-		return 0;
-	}
-
-	/* seek to last byte of device descriptor to determine number of
-	 * configurations */
-	off = lseek(fd, DEVICE_DESC_LENGTH - 1, SEEK_SET);
+	off = lseek(fd, DEVICE_DESC_LENGTH, SEEK_SET);
 	if (off < 0) {
-		usbi_err("seek failed, ret=%d errno=%d", off, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	r = read(fd, &num_configurations, 1);
-	if (r < 0) {
-		usbi_err("read num_configurations failed, ret=%d errno=%d", off, errno);
+		usbi_err("seek failed ret=%d errno=%d", off, errno);
 		return LIBUSB_ERROR_IO;
 	}
 
 	/* might need to skip some configuration descriptors to reach the
 	 * requested configuration */
-	while (num_configurations) {
+	while (config_index) {
 		struct libusb_config_descriptor config;
 
 		/* read first 8 bytes of descriptor */
@@ -357,8 +330,6 @@ static int get_config_descriptor(int fd, int bConfigurationValue,
 		}
 
 		usbi_parse_descriptor(tmp, "bbwbb", &config);
-		if (config.bConfigurationValue == bConfigurationValue)
-			break;
 
 		/* seek forward to end of config */
 		off = lseek(fd, config.wTotalLength - sizeof(tmp), SEEK_CUR);
@@ -367,21 +338,15 @@ static int get_config_descriptor(int fd, int bConfigurationValue,
 			return LIBUSB_ERROR_IO;
 		}
 
-		num_configurations--;
+		config_index--;
 	}
 
-	if (num_configurations == 0)
-		return LIBUSB_ERROR_NOT_FOUND;
-
-	/* copy config-so-far */
-	memcpy(buffer, tmp, sizeof(tmp));
-
 	/* read the rest of the descriptor */
-	r = read(fd, buffer + sizeof(tmp), len - sizeof(tmp));
+	r = read(fd, buffer, len);
 	if (r < 0) {
 		usbi_err("read failed ret=%d errno=%d", r, errno);
 		return LIBUSB_ERROR_IO;
-	} else if (r < (len - sizeof(tmp))) {
+	} else if (r < len) {
 		usbi_err("short output read %d/%d", r, len);
 		return LIBUSB_ERROR_IO;
 	}
@@ -389,8 +354,8 @@ static int get_config_descriptor(int fd, int bConfigurationValue,
 	return 0;
 }
 
-static int op_get_config_descriptor(struct libusb_device *dev, uint8_t config,
-	unsigned char *buffer, size_t len)
+static int op_get_config_descriptor(struct libusb_device *dev,
+	uint8_t config_index, unsigned char *buffer, size_t len)
 {
 	char filename[PATH_MAX + 1];
 	int fd;
@@ -406,7 +371,7 @@ static int op_get_config_descriptor(struct libusb_device *dev, uint8_t config,
 		return LIBUSB_ERROR_IO;
 	}
 
-	r = get_config_descriptor(fd, config, buffer, len);
+	r = get_config_descriptor(fd, config_index, buffer, len);
 	close(fd);
 	return r;
 }
@@ -420,6 +385,7 @@ static int cache_active_config(struct libusb_device *dev, int fd,
 	unsigned char *buf;
 	int r;
 
+	/* FIXME */
 	r = get_config_descriptor(fd, active_config, tmp, sizeof(tmp));
 	if (r < 0) {
 		usbi_err("first read error %d", r);