move descriptor parsing into main library

OS modules now provide functionality for fetching device/config
descriptors

3 files changed, 201 insertions, 100 deletions

diff --git a/libusb/core.c b/libusb/core.c
index 2225106..0464bd8 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -232,6 +232,7 @@ static void discovered_devs_free(struct discovered_devs *discdevs)
 	free(discdevs);
 }
 
+/* allocate a new device with reference count 1 */
 struct libusb_device *usbi_alloc_device(unsigned long session_id)
 {
 	size_t priv_size = usbi_backend->device_priv_size;
@@ -255,6 +256,97 @@ struct libusb_device *usbi_alloc_device(unsigned long session_id)
 	return dev;
 }
 
+/* call the OS discovery routines to populate descriptors etc */
+int usbi_discover_device(struct libusb_device *dev)
+{
+	int r;
+	int i;
+	void *user_data;
+	unsigned char raw_desc[DEVICE_DESC_LENGTH];
+	size_t alloc_size;
+
+	dev->config = NULL;
+
+	r = usbi_backend->begin_discovery(dev, &user_data);
+	if (r < 0)
+		return r;
+	
+	r = usbi_backend->get_device_descriptor(dev, raw_desc, user_data);
+	if (r < 0)
+		goto err;
+
+	usbi_parse_descriptor(raw_desc, "bbWbbbbWWWbbbb", &dev->desc);
+
+	if (dev->desc.bNumConfigurations > USB_MAXCONFIG) {
+		usbi_err("too many configurations");
+		r = -EINVAL;
+		goto err;
+	}
+
+	if (dev->desc.bNumConfigurations < 1) {
+		usbi_dbg("no configurations?");
+		r = -EINVAL;
+		goto err;
+	}
+
+	alloc_size = dev->desc.bNumConfigurations
+		* sizeof(struct libusb_config_descriptor);
+	dev->config = malloc(alloc_size);
+	if (!dev->config) {
+		r = LIBUSB_ERROR_NO_MEM;
+		goto err;
+	}
+
+	memset(dev->config, 0, alloc_size);
+	for (i = 0; i < dev->desc.bNumConfigurations; i++) {
+		unsigned char tmp[8];
+		unsigned char *bigbuffer;
+		struct libusb_config_descriptor config;
+
+		r = usbi_backend->get_config_descriptor(dev, i, tmp, sizeof(tmp),
+			user_data);
+		if (r < 0)
+			goto err;
+
+		usbi_parse_descriptor(tmp, "bbw", &config);
+
+		bigbuffer = malloc(config.wTotalLength);
+		if (!bigbuffer) {
+			r = LIBUSB_ERROR_NO_MEM;
+			goto err;
+		}
+
+		r = usbi_backend->get_config_descriptor(dev, i, bigbuffer,
+			config.wTotalLength, user_data);
+		if (r < 0) {
+			free(bigbuffer);
+			goto err;
+		}
+
+		r = usbi_parse_configuration(&dev->config[i], bigbuffer);
+		free(bigbuffer);
+		if (r < 0) {
+			usbi_err("parse_configuration failed with code %d", r);
+			goto err;
+		} else if (r > 0) {
+			usbi_warn("descriptor data still left\n");
+		}
+	}
+
+	usbi_backend->end_discovery(dev, user_data);
+	return 0;
+
+err:
+	if (dev->config) {
+		usbi_clear_configurations(dev);
+		free(dev->config);
+		dev->config = NULL;
+	}
+
+	usbi_backend->end_discovery(dev, user_data);
+	return r;
+}
+
 struct libusb_device *usbi_get_device_by_session_id(unsigned long session_id)
 {
 	struct libusb_device *dev;
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index 2f70053..ca44512 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -223,6 +223,7 @@ void usbi_io_init(void);
 
 struct libusb_device *usbi_alloc_device(unsigned long session_id);
 struct libusb_device *usbi_get_device_by_session_id(unsigned long session_id);
+int usbi_discover_device(struct libusb_device *dev);
 
 void usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
 	enum libusb_transfer_status status);
@@ -273,6 +274,13 @@ struct usbi_os_backend {
 	int (*open)(struct libusb_device_handle *handle);
 	void (*close)(struct libusb_device_handle *handle);
 
+	int (*begin_discovery)(struct libusb_device *device, void **user_data);
+	int (*get_device_descriptor)(struct libusb_device *device,
+		unsigned char *buffer, void *user_data);
+	int (*get_config_descriptor)(struct libusb_device *device, int index,
+		unsigned char *buffer, size_t len, void *user_data);
+	void (*end_discovery)(struct libusb_device *device, void *user_data);
+
 	int (*set_configuration)(struct libusb_device_handle *handle, int config);
 
 	int (*claim_interface)(struct libusb_device_handle *handle, int iface);
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 22d6b6a..4e1cae1 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -133,132 +133,125 @@ static int op_init(void)
 	return 0;
 }
 
-static int initialize_device(struct libusb_device *dev, uint8_t busnum,
-	uint8_t devaddr)
+struct discovery_data {
+	int fd;
+};
+
+static int op_begin_discovery(struct libusb_device *dev, void **user_data)
 {
 	struct linux_device_priv *priv = __device_priv(dev);
-	char path[PATH_MAX + 1];
-	unsigned char raw_desc[DEVICE_DESC_LENGTH];
-	int fd = 0;
-	int i;
-	int r;
-	int tmp;
-
-	priv->nodepath = NULL;
-	dev->config = NULL;
-	dev->bus_number = busnum;
-	dev->device_address = devaddr;
+	struct discovery_data *ddata = malloc(sizeof(*ddata));
+	if (!ddata)
+		return LIBUSB_ERROR_NO_MEM;
 
-	snprintf(path, PATH_MAX, "%s/%03d/%03d", usbfs_path, busnum, devaddr);
-	usbi_dbg("%s", path);
-	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-		usbi_dbg("open '%s' failed, ret=%d errno=%d", path, fd, errno);
-		/* FIXME this might not be an error if the file has gone away due
-		 * to unplugging */
-		r = -EIO;
-		goto err;
+	ddata->fd = open(priv->nodepath, O_RDONLY);
+	if (ddata->fd < 0) {
+		usbi_dbg("open '%s' failed, ret=%d errno=%d", priv->nodepath,
+			ddata->fd, errno);
+		free(ddata);
+		return LIBUSB_ERROR_IO;
 	}
 
-	/* FIXME: move config parsing into main lib */
-	r = read(fd, raw_desc, DEVICE_DESC_LENGTH);
+	*user_data = ddata;
+	return 0;
+}
+
+static int op_get_device_descriptor(struct libusb_device *device,
+	unsigned char *buffer, void *user_data)
+{
+	struct discovery_data *ddata = user_data;
+	int r = read(ddata->fd, buffer, DEVICE_DESC_LENGTH);
 	if (r < 0) {
 		usbi_err("read failed ret=%d errno=%d", r, errno);
-		goto err;
-	}
-	if (r < DEVICE_DESC_LENGTH) {
+		return LIBUSB_ERROR_IO;
+	} else if (r < DEVICE_DESC_LENGTH) {
 		usbi_err("short descriptor read %d/%d", r, DEVICE_DESC_LENGTH);
-		r = -EIO;
-		goto err;
-	}
-
-	usbi_parse_descriptor(raw_desc, "bbWbbbbWWWbbbb", &dev->desc);
-
-	/* Now try to fetch the rest of the descriptors */
-	if (dev->desc.bNumConfigurations > USB_MAXCONFIG) {
-		usbi_err("too many configurations");
-		r = -EINVAL;
-		goto err;
+		return LIBUSB_ERROR_IO;
 	}
 
-	if (dev->desc.bNumConfigurations < 1) {
-		usbi_dbg("no configurations?");
-		r = -EINVAL;
-		goto err;
-	}
+	return 0;
+}
 
-	tmp = dev->desc.bNumConfigurations * sizeof(struct libusb_config_descriptor);
-	dev->config = malloc(tmp);
-	if (!dev->config) {
-		r = -ENOMEM;
-		goto err;
+static int op_get_config_descriptor(struct libusb_device *device,
+	int config_index, unsigned char *buffer, size_t len, void *user_data)
+{
+	struct discovery_data *ddata = user_data;
+	off_t off;
+	ssize_t r;
+	int fd = ddata->fd;
+
+	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;
 	}
 
-	memset(dev->config, 0, tmp);
-	for (i = 0; i < dev->desc.bNumConfigurations; i++) {
-		unsigned char buffer[8], *bigbuffer;
+	/* might need to skip some configuration descriptors to reach the
+	 * requested index */
+	while (config_index > 0) {
+		unsigned char tmp[8];
 		struct libusb_config_descriptor config;
 
-		/* Get the first 8 bytes to figure out what the total length is */
-		r = read(fd, buffer, sizeof(buffer));
-		if (r < sizeof(buffer)) {
-			usbi_err("short descriptor read (%d/%d)", r, sizeof(buffer));
-			r = -EIO;
-			goto err;
+		/* read first 8 bytes of descriptor */
+		r = read(fd, tmp, sizeof(tmp));
+		if (r < 0) {
+			usbi_err("read failed ret=%d errno=%d", r, errno);
+			return LIBUSB_ERROR_IO;
+		} else if (r < sizeof(tmp)) {
+			usbi_err("short descriptor read %d/%d", r, sizeof(tmp));
+			return LIBUSB_ERROR_IO;
 		}
-
+	
 		usbi_parse_descriptor(buffer, "bbw", &config);
 
-		bigbuffer = malloc(config.wTotalLength);
-		if (!bigbuffer) {
-			r = -ENOMEM;
-			goto err;
+		/* seek forward to end of config */
+		off = lseek(fd, config.wTotalLength - sizeof(tmp), SEEK_CUR);
+		if (off < 0) {
+			usbi_err("seek failed ret=%d errno=%d", off, errno);
+			return LIBUSB_ERROR_IO;
 		}
 
-		/* Read the rest of the config descriptor */
-		memcpy(bigbuffer, buffer, sizeof(buffer));
-
-		tmp = config.wTotalLength - 8;
-		r = read(fd, bigbuffer + 8, tmp);
-		if (r < tmp) {
-			usbi_err("short descriptor read (%d/%d)", r, tmp);
-			free(bigbuffer);
-			r = -EIO;
-			goto err;
-		}
-
-		r = usbi_parse_configuration(&dev->config[i], bigbuffer);
-		free(bigbuffer);
-		if (r < 0) {
-			usbi_err("parse_configuration failed with code %d", r);
-			goto err;
-		}
-		if (r > 0)
-			usbi_warn("descriptor data still left\n");
+		config_index--;
 	}
 
-	priv->nodepath = strdup(path);
-	if (!priv->nodepath) {
-		r = -ENOMEM;
-		goto err;
+	/* read the actual config */
+	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 descriptor read %d/%d", r, len);
+		return LIBUSB_ERROR_IO;
 	}
 
-	close(fd);
 	return 0;
+}
 
-err:
-	if (fd)
-		close(fd);
-	if (dev->config) {
-		usbi_clear_configurations(dev);
-		free(dev->config);
-		dev->config = NULL;
-	}
-	if (priv->nodepath) {
-		free(priv->nodepath);
-		priv->nodepath = NULL;
-	}
-	return r;
+static void op_end_discovery(struct libusb_device *device, void *user_data)
+{
+	struct discovery_data *ddata = user_data;
+	close(ddata->fd);
+	free(ddata);
+}
+
+static int initialize_device(struct libusb_device *dev, uint8_t busnum,
+	uint8_t devaddr)
+{
+	struct linux_device_priv *priv = __device_priv(dev);
+	char path[PATH_MAX + 1];
+
+	priv->nodepath = NULL;
+	dev->bus_number = busnum;
+	dev->device_address = devaddr;
+
+	snprintf(path, PATH_MAX, "%s/%03d/%03d", usbfs_path, busnum, devaddr);
+	usbi_dbg("%s", path);
+
+	priv->nodepath = strdup(path);
+	if (!priv->nodepath)
+		return LIBUSB_ERROR_NO_MEM;
+
+	return 0;
 }
 
 /* open a device file, set up the libusb_device structure for it, and add it to
@@ -297,6 +290,9 @@ static int scan_device(struct discovered_devs **_discdevs, uint8_t busnum,
 		r = initialize_device(dev, busnum, devaddr);
 		if (r < 0)
 			goto out;
+		r = usbi_discover_device(dev);
+		if (r < 0)
+			goto out;
 	}
 
 	discdevs = discovered_devs_append(*_discdevs, dev);
@@ -1212,6 +1208,11 @@ const struct usbi_os_backend linux_usbfs_backend = {
 	.init = op_init,
 	.exit = NULL,
 	.get_device_list = op_get_device_list,
+	.begin_discovery = op_begin_discovery,
+	.get_device_descriptor = op_get_device_descriptor,
+	.get_config_descriptor = op_get_config_descriptor,
+	.end_discovery = op_end_discovery,
+
 	.open = op_open,
 	.close = op_close,
 	.set_configuration = op_set_configuration,