Revert 129069 - Import libusb 1.0.9-rc3 into third_party.

third_party/libusb/libusb/os/linux_usbfs.c

Index: third_party/libusb/libusb/os/linux_usbfs.c
===================================================================
--- third_party/libusb/libusb/os/linux_usbfs.c	(revision 129100)
+++ third_party/libusb/libusb/os/linux_usbfs.c	(working copy)
@@ -1,2313 +0,0 @@
-/*
- * Linux usbfs backend for libusb
- * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
- * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <config.h>
-#include <ctype.h>
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <poll.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/ioctl.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <sys/utsname.h>
-#include <unistd.h>
-
-#include "libusb.h"
-#include "libusbi.h"
-#include "linux_usbfs.h"
-
-/* sysfs vs usbfs:
- * opening a usbfs node causes the device to be resumed, so we attempt to
- * avoid this during enumeration.
- *
- * sysfs allows us to read the kernel's in-memory copies of device descriptors
- * and so forth, avoiding the need to open the device:
- *  - The binary "descriptors" file was added in 2.6.23.
- *  - The "busnum" file was added in 2.6.22
- *  - The "devnum" file has been present since pre-2.6.18
- *  - the "bConfigurationValue" file has been present since pre-2.6.18
- *
- * If we have bConfigurationValue, busnum, and devnum, then we can determine
- * the active configuration without having to open the usbfs node in RDWR mode.
- * We assume this is the case if we see the busnum file (indicates 2.6.22+).
- * The busnum file is important as that is the only way we can relate sysfs
- * devices to usbfs nodes.
- *
- * If we also have descriptors, we can obtain the device descriptor and active 
- * configuration without touching usbfs at all.
- *
- * The descriptors file originally only contained the active configuration
- * descriptor alongside the device descriptor, but all configurations are
- * included as of Linux 2.6.26.
- */
-
-/* endianness for multi-byte fields:
- *
- * Descriptors exposed by usbfs have the multi-byte fields in the device
- * descriptor as host endian. Multi-byte fields in the other descriptors are
- * bus-endian. The kernel documentation says otherwise, but it is wrong.
- */
-
-static const char *usbfs_path = NULL;
-
-/* Linux 2.6.32 adds support for a bulk continuation URB flag. this basically
- * allows us to mark URBs as being part of a specific logical transfer when
- * we submit them to the kernel. then, on any error except a cancellation, all
- * URBs within that transfer will be cancelled and no more URBs will be
- * accepted for the transfer, meaning that no more data can creep in.
- *
- * The BULK_CONTINUATION flag must be set on all URBs within a bulk transfer
- * (in either direction) except the first.
- * For IN transfers, we must also set SHORT_NOT_OK on all URBs except the
- * last; it means that the kernel should treat a short reply as an error.
- * For OUT transfers, SHORT_NOT_OK must not be set. it isn't needed (OUT
- * transfers can't be short unless there's already some sort of error), and
- * setting this flag is disallowed (a kernel with USB debugging enabled will
- * reject such URBs).
- */
-static int supports_flag_bulk_continuation = -1;
-
-/* clock ID for monotonic clock, as not all clock sources are available on all
- * systems. appropriate choice made at initialization time. */
-static clockid_t monotonic_clkid = -1;
-
-/* do we have a busnum to relate devices? this also implies that we can read
- * the active configuration through bConfigurationValue */
-static int sysfs_can_relate_devices = 0;
-
-/* do we have a descriptors file? */
-static int sysfs_has_descriptors = 0;
-
-struct linux_device_priv {
-	char *sysfs_dir;
-	unsigned char *dev_descriptor;
-	unsigned char *config_descriptor;
-};
-
-struct linux_device_handle_priv {
-	int fd;
-};
-
-enum reap_action {
-	NORMAL = 0,
-	/* submission failed after the first URB, so await cancellation/completion
-	 * of all the others */
-	SUBMIT_FAILED,
-
-	/* cancelled by user or timeout */
-	CANCELLED,
-
-	/* completed multi-URB transfer in non-final URB */
-	COMPLETED_EARLY,
-
-	/* one or more urbs encountered a low-level error */
-	ERROR,
-};
-
-struct linux_transfer_priv {
-	union {
-		struct usbfs_urb *urbs;
-		struct usbfs_urb **iso_urbs;
-	};
-
-	enum reap_action reap_action;
-	int num_urbs;
-	unsigned int num_retired;
-	enum libusb_transfer_status reap_status;
-
-	/* next iso packet in user-supplied transfer to be populated */
-	int iso_packet_offset;
-};
-
-static void _get_usbfs_path(struct libusb_device *dev, char *path)
-{
-	snprintf(path, PATH_MAX, "%s/%03d/%03d", usbfs_path, dev->bus_number,
-		dev->device_address);
-}
-
-static struct linux_device_priv *_device_priv(struct libusb_device *dev)
-{
-	return (struct linux_device_priv *) dev->os_priv;
-}
-
-static struct linux_device_handle_priv *_device_handle_priv(
-	struct libusb_device_handle *handle)
-{
-	return (struct linux_device_handle_priv *) handle->os_priv;
-}
-
-static int check_usb_vfs(const char *dirname)
-{
-	DIR *dir;
-	struct dirent *entry;
-	int found = 0;
-
-	dir = opendir(dirname);
-	if (!dir)
-		return 0;
-
-	while ((entry = readdir(dir)) != NULL) {
-		if (entry->d_name[0] == '.')
-			continue;
-
-		/* We assume if we find any files that it must be the right place */
-		found = 1;
-		break;
-	}
-
-	closedir(dir);
-	return found;
-}
-
-static const char *find_usbfs_path(void)
-{
-	const char *path = "/dev/bus/usb";
-	const char *ret = NULL;
-
-	if (check_usb_vfs(path)) {
-		ret = path;
-	} else {
-		path = "/proc/bus/usb";
-		if (check_usb_vfs(path))
-			ret = path;
-	}
-
-	usbi_dbg("found usbfs at %s", ret);
-	return ret;
-}
-
-/* the monotonic clock is not usable on all systems (e.g. embedded ones often
- * seem to lack it). fall back to REALTIME if we have to. */
-static clockid_t find_monotonic_clock(void)
-{
-	struct timespec ts;
-	int r;
-
-#ifdef CLOCK_MONOTONIC
-	/* Linux 2.6.28 adds CLOCK_MONOTONIC_RAW but we don't use it
-	 * because it's not available through timerfd */
-	r = clock_gettime(CLOCK_MONOTONIC, &ts);
-	if (r == 0)
-		return CLOCK_MONOTONIC;
-	usbi_dbg("monotonic clock doesn't work, errno %d", errno);
-#endif
-
-	return CLOCK_REALTIME;
-}
-
-/* bulk continuation URB flag available from Linux 2.6.32 */
-static int check_flag_bulk_continuation(void)
-{
-	struct utsname uts;
-	int atoms, major, minor, sublevel;
-
-	if (uname(&uts) < 0)
-		return -1;
-	atoms = sscanf(uts.release, "%d.%d.%d", &major, &minor, &sublevel);
-	if (atoms < 1)
-		return -1;
-
-	if (major > 2)
-		return 1;
-	if (major < 2)
-		return 0;
-
-	if (atoms < 2)
-		return 0;
-
-	/* major == 2 */
-	if (minor < 6)
-		return 0;
-	if (minor > 6) /* Does not exist, just here for correctness */
-		return 1;
-
-	/* 2.6.x */
-	if (3 == atoms && sublevel >= 32)
-		return 1;
-
-	return 0;
-}
-
-/* Return 1 if filename exists inside dirname in sysfs.
-   SYSFS_DEVICE_PATH is assumed to be the beginning of the path. */
-static int sysfs_has_file(const char *dirname, const char *filename)
-{
-	struct stat statbuf;
-	char path[PATH_MAX];
-	int r;
-
-	snprintf(path, PATH_MAX, "%s/%s/%s", SYSFS_DEVICE_PATH, dirname, filename);
-	r = stat(path, &statbuf);
-	if (r == 0 && S_ISREG(statbuf.st_mode))
-		return 1;
-
-	return 0;
-}
-
-static int op_init(struct libusb_context *ctx)
-{
-	struct stat statbuf;
-	int r;
-
-	usbfs_path = find_usbfs_path();
-	if (!usbfs_path) {
-		usbi_err(ctx, "could not find usbfs");
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	if (monotonic_clkid == -1)
-		monotonic_clkid = find_monotonic_clock();
-
-	if (supports_flag_bulk_continuation == -1) {
-		supports_flag_bulk_continuation = check_flag_bulk_continuation();
-		if (supports_flag_bulk_continuation == -1) {
-			usbi_err(ctx, "error checking for bulk continuation support");
-			return LIBUSB_ERROR_OTHER;
-		}
-	}
-
-	if (supports_flag_bulk_continuation)
-		usbi_dbg("bulk continuation flag supported");
-
-	r = stat(SYSFS_DEVICE_PATH, &statbuf);
-	if (r == 0 && S_ISDIR(statbuf.st_mode)) {
-		DIR *devices = opendir(SYSFS_DEVICE_PATH);
-		struct dirent *entry;
-
-		usbi_dbg("found usb devices in sysfs");
-
-		if (!devices) {
-			usbi_err(ctx, "opendir devices failed errno=%d", errno);
-			return LIBUSB_ERROR_IO;
-		}
-
-		/* Make sure sysfs supports all the required files. If it
-		 * does not, then usbfs will be used instead.  Determine
-		 * this by looping through the directories in
-		 * SYSFS_DEVICE_PATH.  With the assumption that there will
-		 * always be subdirectories of the name usbN (usb1, usb2,
-		 * etc) representing the root hubs, check the usbN
-		 * subdirectories to see if they have all the needed files.
-		 * This algorithm uses the usbN subdirectories (root hubs)
-		 * because a device disconnection will cause a race
-		 * condition regarding which files are available, sometimes
-		 * causing an incorrect result.  The root hubs are used
-		 * because it is assumed that they will always be present.
-		 * See the "sysfs vs usbfs" comment at the top of this file
-		 * for more details.  */
-		while ((entry = readdir(devices))) {
-			int has_busnum=0, has_devnum=0, has_descriptors=0;
-			int has_configuration_value=0;
-
-			/* Only check the usbN directories. */
-			if (strncmp(entry->d_name, "usb", 3) != 0)
-				continue;
-
-			/* Check for the files libusb needs from sysfs. */
-			has_busnum = sysfs_has_file(entry->d_name, "busnum");
-			has_devnum = sysfs_has_file(entry->d_name, "devnum");
-			has_descriptors = sysfs_has_file(entry->d_name, "descriptors");
-			has_configuration_value = sysfs_has_file(entry->d_name, "bConfigurationValue");
-
-			if (has_busnum && has_devnum && has_configuration_value)
-				sysfs_can_relate_devices = 1;
-			if (has_descriptors)
-				sysfs_has_descriptors = 1;
-
-			/* Only need to check until we've found ONE device which
-			   has all the attributes. */
-			if (sysfs_has_descriptors && sysfs_can_relate_devices)
-				break;
-		}
-		closedir(devices);
-
-		/* Only use sysfs descriptors if the rest of
-		   sysfs will work for libusb. */
-		if (!sysfs_can_relate_devices)
-			sysfs_has_descriptors = 0;
-	} else {
-		usbi_dbg("sysfs usb info not available");
-		sysfs_has_descriptors = 0;
-		sysfs_can_relate_devices = 0;
-	}
-
-	return 0;
-}
-
-static int usbfs_get_device_descriptor(struct libusb_device *dev,
-	unsigned char *buffer)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-
-	/* return cached copy */
-	memcpy(buffer, priv->dev_descriptor, DEVICE_DESC_LENGTH);
-	return 0;
-}
-
-static int _open_sysfs_attr(struct libusb_device *dev, const char *attr)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-	char filename[PATH_MAX];
-	int fd;
-
-	snprintf(filename, PATH_MAX, "%s/%s/%s",
-		SYSFS_DEVICE_PATH, priv->sysfs_dir, attr);
-	fd = open(filename, O_RDONLY);
-	if (fd < 0) {
-		usbi_err(DEVICE_CTX(dev),
-			"open %s failed ret=%d errno=%d", filename, fd, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return fd;
-}
-
-/* Note only suitable for attributes which always read >= 0, < 0 is error */
-static int __read_sysfs_attr(struct libusb_context *ctx,
-	const char *devname, const char *attr)
-{
-	char filename[PATH_MAX];
-	FILE *f;
-	int r, value;
-
-	snprintf(filename, PATH_MAX, "%s/%s/%s", SYSFS_DEVICE_PATH,
-		 devname, attr);
-	f = fopen(filename, "r");
-	if (f == NULL) {
-		if (errno == ENOENT) {
-			/* File doesn't exist. Assume the device has been
-			   disconnected (see trac ticket #70). */
-			return LIBUSB_ERROR_NO_DEVICE;
-		}
-		usbi_err(ctx, "open %s failed errno=%d", filename, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	r = fscanf(f, "%d", &value);
-	fclose(f);
-	if (r != 1) {
-		usbi_err(ctx, "fscanf %s returned %d, errno=%d", attr, r, errno);
-		return LIBUSB_ERROR_NO_DEVICE; /* For unplug race (trac #70) */
-	}
-	if (value < 0) {
-		usbi_err(ctx, "%s contains a negative value", filename);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return value;
-}
-
-static int sysfs_get_device_descriptor(struct libusb_device *dev,
-	unsigned char *buffer)
-{
-	int fd;
-	ssize_t r;
-
-	/* sysfs provides access to an in-memory copy of the device descriptor,
-	 * so we use that rather than keeping our own copy */
-
-	fd = _open_sysfs_attr(dev, "descriptors");
-	if (fd < 0)
-		return fd;
-
-	r = read(fd, buffer, DEVICE_DESC_LENGTH);;
-	close(fd);
-	if (r < 0) {
-		usbi_err(DEVICE_CTX(dev), "read failed, ret=%d errno=%d", fd, errno);
-		return LIBUSB_ERROR_IO;
-	} else if (r < DEVICE_DESC_LENGTH) {
-		usbi_err(DEVICE_CTX(dev), "short read %d/%d", r, DEVICE_DESC_LENGTH);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return 0;
-}
-
-static int op_get_device_descriptor(struct libusb_device *dev,
-	unsigned char *buffer, int *host_endian)
-{
-	if (sysfs_has_descriptors) {
-		return sysfs_get_device_descriptor(dev, buffer);
-	} else {
-		*host_endian = 1;
-		return usbfs_get_device_descriptor(dev, buffer);
-	}
-}
-
-static int usbfs_get_active_config_descriptor(struct libusb_device *dev,
-	unsigned char *buffer, size_t len)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-	if (!priv->config_descriptor)
-		return LIBUSB_ERROR_NOT_FOUND; /* device is unconfigured */
-
-	/* retrieve cached copy */
-	memcpy(buffer, priv->config_descriptor, len);
-	return 0;
-}
-
-/* read the bConfigurationValue for a device */
-static int sysfs_get_active_config(struct libusb_device *dev, int *config)
-{
-	char *endptr;
-	char tmp[4] = {0, 0, 0, 0};
-	long num;
-	int fd;
-	ssize_t r;
-
-	fd = _open_sysfs_attr(dev, "bConfigurationValue");
-	if (fd < 0)
-		return fd;
-
-	r = read(fd, tmp, sizeof(tmp));
-	close(fd);
-	if (r < 0) {
-		usbi_err(DEVICE_CTX(dev), 
-			"read bConfigurationValue failed ret=%d errno=%d", r, errno);
-		return LIBUSB_ERROR_IO;
-	} else if (r == 0) {
-		usbi_err(DEVICE_CTX(dev), "device unconfigured");
-		*config = -1;
-		return 0;
-	}
-
-	if (tmp[sizeof(tmp) - 1] != 0) {
-		usbi_err(DEVICE_CTX(dev), "not null-terminated?");
-		return LIBUSB_ERROR_IO;
-	} else if (tmp[0] == 0) {
-		usbi_err(DEVICE_CTX(dev), "no configuration value?");
-		return LIBUSB_ERROR_IO;
-	}
-
-	num = strtol(tmp, &endptr, 10);
-	if (endptr == tmp) {
-		usbi_err(DEVICE_CTX(dev), "error converting '%s' to integer", tmp);
-		return LIBUSB_ERROR_IO;
-	}
-
-	*config = (int) num;
-	return 0;
-}
-
-/* takes a usbfs/descriptors fd seeked to the start of a configuration, and
- * seeks to the next one. */
-static int seek_to_next_config(struct libusb_context *ctx, int fd,
-	int host_endian)
-{
-	struct libusb_config_descriptor config;
-	unsigned char tmp[6];
-	off_t off;
-	ssize_t r;
-
-	/* read first 6 bytes of descriptor */
-	r = read(fd, tmp, sizeof(tmp));
-	if (r < 0) {
-		usbi_err(ctx, "read failed ret=%d errno=%d", r, errno);
-		return LIBUSB_ERROR_IO;
-	} else if (r < sizeof(tmp)) {
-		usbi_err(ctx, "short descriptor read %d/%d", r, sizeof(tmp));
-		return LIBUSB_ERROR_IO;
-	}
-
-	/* seek forward to end of config */
-	usbi_parse_descriptor(tmp, "bbwbb", &config, host_endian);
-	off = lseek(fd, config.wTotalLength - sizeof(tmp), SEEK_CUR);
-	if (off < 0) {
-		usbi_err(ctx, "seek failed ret=%d errno=%d", off, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return 0;
-}
-
-static int sysfs_get_active_config_descriptor(struct libusb_device *dev,
-	unsigned char *buffer, size_t len)
-{
-	int fd;
-	ssize_t r;
-	off_t off;
-	int to_copy;
-	int config;
-	unsigned char tmp[6];
-
-	r = sysfs_get_active_config(dev, &config);
-	if (r < 0)
-		return r;
-	if (config == -1)
-		return LIBUSB_ERROR_NOT_FOUND;
-
-	usbi_dbg("active configuration %d", config);
-
-	/* sysfs provides access to an in-memory copy of the device descriptor,
-	 * so we use that rather than keeping our own copy */
-
-	fd = _open_sysfs_attr(dev, "descriptors");
-	if (fd < 0)
-		return fd;
-
-	/* device might have been unconfigured since we read bConfigurationValue,
-	 * so first check that there is any config descriptor data at all... */
-	off = lseek(fd, 0, SEEK_END);
-	if (off < 1) {
-		usbi_err(DEVICE_CTX(dev), "end seek failed, ret=%d errno=%d",
-			off, errno);
-		close(fd);
-		return LIBUSB_ERROR_IO;
-	} else if (off == DEVICE_DESC_LENGTH) {
-		close(fd);
-		return LIBUSB_ERROR_NOT_FOUND;
-	}
-
-	off = lseek(fd, DEVICE_DESC_LENGTH, SEEK_SET);
-	if (off < 0) {
-		usbi_err(DEVICE_CTX(dev), "seek failed, ret=%d errno=%d", off, errno);
-		close(fd);
-		return LIBUSB_ERROR_IO;
-	}
-
-	/* unbounded loop: we expect the descriptor to be present under all
-	 * circumstances */
-	while (1) {
-		r = read(fd, tmp, sizeof(tmp));
-		if (r < 0) {
-			usbi_err(DEVICE_CTX(dev), "read failed, ret=%d errno=%d",
-				fd, errno);
-			return LIBUSB_ERROR_IO;
-		} else if (r < sizeof(tmp)) {
-			usbi_err(DEVICE_CTX(dev), "short read %d/%d", r, sizeof(tmp));
-			return LIBUSB_ERROR_IO;
-		}
-
-		/* check bConfigurationValue */
-		if (tmp[5] == config)
-			break;
-
-		/* try the next descriptor */
-		off = lseek(fd, 0 - sizeof(tmp), SEEK_CUR);
-		if (off < 0)
-			return LIBUSB_ERROR_IO;
-
-		r = seek_to_next_config(DEVICE_CTX(dev), fd, 0);
-		if (r < 0)
-			return r;
-	}
-
-	to_copy = (len < sizeof(tmp)) ? len : sizeof(tmp);
-	memcpy(buffer, tmp, to_copy);
-	if (len > sizeof(tmp)) {
-		r = read(fd, buffer + sizeof(tmp), len - sizeof(tmp));
-		if (r < 0) {
-			usbi_err(DEVICE_CTX(dev), "read failed, ret=%d errno=%d",
-				fd, errno);
-			r = LIBUSB_ERROR_IO;
-		} else if (r == 0) {
-			usbi_dbg("device is unconfigured");
-			r = LIBUSB_ERROR_NOT_FOUND;
-		} else if (r < len - sizeof(tmp)) {
-			usbi_err(DEVICE_CTX(dev), "short read %d/%d", r, len);
-			r = LIBUSB_ERROR_IO;
-		}
-	} else {
-		r = 0;
-	}
-
-	close(fd);
-	return r;
-}
-
-static int op_get_active_config_descriptor(struct libusb_device *dev,
-	unsigned char *buffer, size_t len, int *host_endian)
-{
-	if (sysfs_has_descriptors) {
-		return sysfs_get_active_config_descriptor(dev, buffer, len);
-	} else {
-		return usbfs_get_active_config_descriptor(dev, buffer, len);
-	}
-}
-
-/* takes a usbfs fd, attempts to find the requested config and copy a certain
- * amount of it into an output buffer. */
-static int get_config_descriptor(struct libusb_context *ctx, int fd,
-	uint8_t config_index, unsigned char *buffer, size_t len)
-{
-	off_t off;
-	ssize_t r;
-
-	off = lseek(fd, DEVICE_DESC_LENGTH, SEEK_SET);
-	if (off < 0) {
-		usbi_err(ctx, "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 (config_index > 0) {
-		r = seek_to_next_config(ctx, fd, 1);
-		if (r < 0)
-			return r;
-		config_index--;
-	}
-
-	/* read the rest of the descriptor */
-	r = read(fd, buffer, len);
-	if (r < 0) {
-		usbi_err(ctx, "read failed ret=%d errno=%d", r, errno);
-		return LIBUSB_ERROR_IO;
-	} else if (r < len) {
-		usbi_err(ctx, "short output read %d/%d", r, len);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return 0;
-}
-
-static int op_get_config_descriptor(struct libusb_device *dev,
-	uint8_t config_index, unsigned char *buffer, size_t len, int *host_endian)
-{
-	char filename[PATH_MAX];
-	int fd;
-	int r;
-
-	/* always read from usbfs: sysfs only has the active descriptor
-	 * this will involve waking the device up, but oh well! */
-
-	/* FIXME: the above is no longer true, new kernels have all descriptors
-	 * in the descriptors file. but its kinda hard to detect if the kernel
-	 * is sufficiently new. */
-
-	_get_usbfs_path(dev, filename);
-	fd = open(filename, O_RDONLY);
-	if (fd < 0) {
-		usbi_err(DEVICE_CTX(dev),
-			"open '%s' failed, ret=%d errno=%d", filename, fd, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	r = get_config_descriptor(DEVICE_CTX(dev), fd, config_index, buffer, len);
-	close(fd);
-	return r;
-}
-
-/* cache the active config descriptor in memory. a value of -1 means that
- * we aren't sure which one is active, so just assume the first one. 
- * only for usbfs. */
-static int cache_active_config(struct libusb_device *dev, int fd,
-	int active_config)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-	struct libusb_config_descriptor config;
-	unsigned char tmp[8];
-	unsigned char *buf;
-	int idx;
-	int r;
-
-	if (active_config == -1) {
-		idx = 0;
-	} else {
-		r = usbi_get_config_index_by_value(dev, active_config, &idx);
-		if (r < 0)
-			return r;
-		if (idx == -1)
-			return LIBUSB_ERROR_NOT_FOUND;
-	}
-
-	r = get_config_descriptor(DEVICE_CTX(dev), fd, idx, tmp, sizeof(tmp));
-	if (r < 0) {
-		usbi_err(DEVICE_CTX(dev), "first read error %d", r);
-		return r;
-	}
-
-	usbi_parse_descriptor(tmp, "bbw", &config, 0);
-	buf = malloc(config.wTotalLength);
-	if (!buf)
-		return LIBUSB_ERROR_NO_MEM;
-
-	r = get_config_descriptor(DEVICE_CTX(dev), fd, idx, buf,
-		config.wTotalLength);
-	if (r < 0) {
-		free(buf);
-		return r;
-	}
-
-	if (priv->config_descriptor)
-		free(priv->config_descriptor);
-	priv->config_descriptor = buf;
-	return 0;
-}
-
-/* send a control message to retrieve active configuration */
-static int usbfs_get_active_config(struct libusb_device *dev, int fd)
-{
-	unsigned char active_config = 0;
-	int r;
-
-	struct usbfs_ctrltransfer ctrl = {
-		.bmRequestType = LIBUSB_ENDPOINT_IN,
-		.bRequest = LIBUSB_REQUEST_GET_CONFIGURATION,
-		.wValue = 0,
-		.wIndex = 0,
-		.wLength = 1,
-		.timeout = 1000,
-		.data = &active_config
-	};
-
-	r = ioctl(fd, IOCTL_USBFS_CONTROL, &ctrl);
-	if (r < 0) {
-		if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		/* we hit this error path frequently with buggy devices :( */
-		usbi_warn(DEVICE_CTX(dev),
-			"get_configuration failed ret=%d errno=%d", r, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	return active_config;
-}
-
-static int initialize_device(struct libusb_device *dev, uint8_t busnum,
-	uint8_t devaddr, const char *sysfs_dir)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-	unsigned char *dev_buf;
-	char path[PATH_MAX];
-	int fd, speed;
-	int active_config = 0;
-	int device_configured = 1;
-	ssize_t r;
-
-	dev->bus_number = busnum;
-	dev->device_address = devaddr;
-
-	if (sysfs_dir) {
-		priv->sysfs_dir = malloc(strlen(sysfs_dir) + 1);
-		if (!priv->sysfs_dir)
-			return LIBUSB_ERROR_NO_MEM;
-		strcpy(priv->sysfs_dir, sysfs_dir);
-
-		/* Note speed can contain 1.5, in this case __read_sysfs_attr
-		   will stop parsing at the '.' and return 1 */
-		speed = __read_sysfs_attr(DEVICE_CTX(dev), sysfs_dir, "speed");
-		if (speed >= 0) {
-			switch (speed) {
-			case     1: dev->speed = LIBUSB_SPEED_LOW; break;
-			case    12: dev->speed = LIBUSB_SPEED_FULL; break;
-			case   480: dev->speed = LIBUSB_SPEED_HIGH; break;
-			case  5000: dev->speed = LIBUSB_SPEED_SUPER; break;
-			default:
-				usbi_warn(DEVICE_CTX(dev), "Unknown device speed: %d Mbps", speed);
-			}
-		}
-	}
-
-	if (sysfs_has_descriptors)
-		return 0;
-
-	/* cache device descriptor in memory so that we can retrieve it later
-	 * without waking the device up (op_get_device_descriptor) */
-
-	priv->dev_descriptor = NULL;
-	priv->config_descriptor = NULL;
-
-	if (sysfs_can_relate_devices) {
-		int tmp = sysfs_get_active_config(dev, &active_config);
-		if (tmp < 0)
-			return tmp;
-		if (active_config == -1)
-			device_configured = 0;
-	}
-
-	_get_usbfs_path(dev, path);
-	fd = open(path, O_RDWR);
-	if (fd < 0 && errno == EACCES) {
-		fd = open(path, O_RDONLY);
-		/* if we only have read-only access to the device, we cannot
-		 * send a control message to determine the active config. just
-		 * assume the first one is active. */
-		active_config = -1;
-	}
-
-	if (fd < 0) {
-		usbi_err(DEVICE_CTX(dev), "open failed, ret=%d errno=%d", fd, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	if (!sysfs_can_relate_devices) {
-		if (active_config == -1) {
-			/* if we only have read-only access to the device, we cannot
-			 * send a control message to determine the active config. just
-			 * assume the first one is active. */
-			usbi_warn(DEVICE_CTX(dev), "access to %s is read-only; cannot "
-				"determine active configuration descriptor", path);
-		} else {
-			active_config = usbfs_get_active_config(dev, fd);
-			if (active_config == LIBUSB_ERROR_IO) {
-				/* buggy devices sometimes fail to report their active config.
-				 * assume unconfigured and continue the probing */
-				usbi_warn(DEVICE_CTX(dev), "couldn't query active "
-					"configuration, assumung unconfigured");
-				device_configured = 0;
-			} else if (active_config < 0) {
-				close(fd);
-				return active_config;
-			} else if (active_config == 0) {
-				/* some buggy devices have a configuration 0, but we're
-				 * reaching into the corner of a corner case here, so let's
-				 * not support buggy devices in these circumstances.
-				 * stick to the specs: a configuration value of 0 means
-				 * unconfigured. */
-				usbi_dbg("active cfg 0? assuming unconfigured device");
-				device_configured = 0;
-			}
-		}
-	}
-
-	dev_buf = malloc(DEVICE_DESC_LENGTH);
-	if (!dev_buf) {
-		close(fd);
-		return LIBUSB_ERROR_NO_MEM;
-	}
-
-	r = read(fd, dev_buf, DEVICE_DESC_LENGTH);
-	if (r < 0) {
-		usbi_err(DEVICE_CTX(dev),
-			"read descriptor failed ret=%d errno=%d", fd, errno);
-		free(dev_buf);
-		close(fd);
-		return LIBUSB_ERROR_IO;
-	} else if (r < DEVICE_DESC_LENGTH) {
-		usbi_err(DEVICE_CTX(dev), "short descriptor read (%d)", r);
-		free(dev_buf);
-		close(fd);
-		return LIBUSB_ERROR_IO;
-	}
-
-	/* bit of a hack: set num_configurations now because cache_active_config()
-	 * calls usbi_get_config_index_by_value() which uses it */
-	dev->num_configurations = dev_buf[DEVICE_DESC_LENGTH - 1];
-
-	if (device_configured) {
-		r = cache_active_config(dev, fd, active_config);
-		if (r < 0) {
-			close(fd);
-			free(dev_buf);
-			return r;
-		}
-	}
-
-	close(fd);
-	priv->dev_descriptor = dev_buf;
-	return 0;
-}
-
-static int enumerate_device(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs, uint8_t busnum, uint8_t devaddr,
-	const char *sysfs_dir)
-{
-	struct discovered_devs *discdevs;
-	unsigned long session_id;
-	int need_unref = 0;
-	struct libusb_device *dev;
-	int r = 0;
-
-	/* FIXME: session ID is not guaranteed unique as addresses can wrap and
-	 * will be reused. instead we should add a simple sysfs attribute with
-	 * a session ID. */
-	session_id = busnum << 8 | devaddr;
-	usbi_dbg("busnum %d devaddr %d session_id %ld", busnum, devaddr,
-		session_id);
-
-	dev = usbi_get_device_by_session_id(ctx, session_id);
-	if (dev) {
-		usbi_dbg("using existing device for %d/%d (session %ld)",
-			busnum, devaddr, session_id);
-	} else {
-		usbi_dbg("allocating new device for %d/%d (session %ld)",
-			busnum, devaddr, session_id);
-		dev = usbi_alloc_device(ctx, session_id);
-		if (!dev)
-			return LIBUSB_ERROR_NO_MEM;
-		need_unref = 1;
-		r = initialize_device(dev, busnum, devaddr, sysfs_dir);
-		if (r < 0)
-			goto out;
-		r = usbi_sanitize_device(dev);
-		if (r < 0)
-			goto out;
-	}
-
-	discdevs = discovered_devs_append(*_discdevs, dev);
-	if (!discdevs)
-		r = LIBUSB_ERROR_NO_MEM;
-	else
-		*_discdevs = discdevs;
-
-out:
-	if (need_unref)
-		libusb_unref_device(dev);
-	return r;
-}
-
-/* open a bus directory and adds all discovered devices to discdevs. on
- * failure (non-zero return) the pre-existing discdevs should be destroyed
- * (and devices freed). on success, the new discdevs pointer should be used
- * as it may have been moved. */
-static int usbfs_scan_busdir(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs, uint8_t busnum)
-{
-	DIR *dir;
-	char dirpath[PATH_MAX];
-	struct dirent *entry;
-	struct discovered_devs *discdevs = *_discdevs;
-	int r = LIBUSB_ERROR_IO;
-
-	snprintf(dirpath, PATH_MAX, "%s/%03d", usbfs_path, busnum);
-	usbi_dbg("%s", dirpath);
-	dir = opendir(dirpath);
-	if (!dir) {
-		usbi_err(ctx, "opendir '%s' failed, errno=%d", dirpath, errno);
-		/* FIXME: should handle valid race conditions like hub unplugged
-		 * during directory iteration - this is not an error */
-		return r;
-	}
-
-	while ((entry = readdir(dir))) {
-		int devaddr;
-
-		if (entry->d_name[0] == '.')
-			continue;
-
-		devaddr = atoi(entry->d_name);
-		if (devaddr == 0) {
-			usbi_dbg("unknown dir entry %s", entry->d_name);
-			continue;
-		}
-
-		if (enumerate_device(ctx, &discdevs, busnum, (uint8_t) devaddr, NULL)) {
-			usbi_dbg("failed to enumerate dir entry %s", entry->d_name);
-			continue;
-		}
-
-		r = 0;
-	}
-
-	if (!r)
-		*_discdevs = discdevs;
-	closedir(dir);
-	return r;
-}
-
-static int usbfs_get_device_list(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs)
-{
-	struct dirent *entry;
-	DIR *buses = opendir(usbfs_path);
-	struct discovered_devs *discdevs = *_discdevs;
-	int r = 0;
-
-	if (!buses) {
-		usbi_err(ctx, "opendir buses failed errno=%d", errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	while ((entry = readdir(buses))) {
-		struct discovered_devs *discdevs_new = discdevs;
-		int busnum;
-
-		if (entry->d_name[0] == '.')
-			continue;
-
-		busnum = atoi(entry->d_name);
-		if (busnum == 0) {
-			usbi_dbg("unknown dir entry %s", entry->d_name);
-			continue;
-		}
-
-		r = usbfs_scan_busdir(ctx, &discdevs_new, busnum);
-		if (r < 0)
-			goto out;
-		discdevs = discdevs_new;
-	}
-
-out:
-	closedir(buses);
-	*_discdevs = discdevs;
-	return r;
-
-}
-
-static int sysfs_scan_device(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs, const char *devname)
-{
-	int busnum;
-	int devaddr;
-
-	usbi_dbg("scan %s", devname);
-
-	busnum = __read_sysfs_attr(ctx, devname, "busnum");
-	if (busnum < 0)
-		return busnum;
-
-	devaddr = __read_sysfs_attr(ctx, devname, "devnum");
-	if (devaddr < 0)
-		return devaddr;
-
-	usbi_dbg("bus=%d dev=%d", busnum, devaddr);
-	if (busnum > 255 || devaddr > 255)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
-	return enumerate_device(ctx, _discdevs, busnum & 0xff, devaddr & 0xff,
-		devname);
-}
-
-static int sysfs_get_device_list(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs)
-{
-	struct discovered_devs *discdevs = *_discdevs;
-	DIR *devices = opendir(SYSFS_DEVICE_PATH);
-	struct dirent *entry;
-	int r = LIBUSB_ERROR_IO;
-
-	if (!devices) {
-		usbi_err(ctx, "opendir devices failed errno=%d", errno);
-		return r;
-	}
-
-	while ((entry = readdir(devices))) {
-		struct discovered_devs *discdevs_new = discdevs;
-
-		if ((!isdigit(entry->d_name[0]) && strncmp(entry->d_name, "usb", 3))
-				|| strchr(entry->d_name, ':'))
-			continue;
-
-		if (sysfs_scan_device(ctx, &discdevs_new, entry->d_name)) {
-			usbi_dbg("failed to enumerate dir entry %s", entry->d_name);
-			continue;
-		}
-
-		r = 0;
-		discdevs = discdevs_new;
-	}
-
-	if (!r)
-		*_discdevs = discdevs;
-	closedir(devices);
-	return r;
-}
-
-static int op_get_device_list(struct libusb_context *ctx,
-	struct discovered_devs **_discdevs)
-{
-	/* we can retrieve device list and descriptors from sysfs or usbfs.
-	 * sysfs is preferable, because if we use usbfs we end up resuming
-	 * any autosuspended USB devices. however, sysfs is not available
-	 * everywhere, so we need a usbfs fallback too.
-	 *
-	 * as described in the "sysfs vs usbfs" comment at the top of this
-	 * file, sometimes we have sysfs but not enough information to
-	 * relate sysfs devices to usbfs nodes.  op_init() determines the
-	 * adequacy of sysfs and sets sysfs_can_relate_devices.
-	 */
-	if (sysfs_can_relate_devices != 0)
-		return sysfs_get_device_list(ctx, _discdevs);
-	else
-		return usbfs_get_device_list(ctx, _discdevs);
-}
-
-static int op_open(struct libusb_device_handle *handle)
-{
-	struct linux_device_handle_priv *hpriv = _device_handle_priv(handle);
-	char filename[PATH_MAX];
-
-	_get_usbfs_path(handle->dev, filename);
-	usbi_dbg("opening %s", filename);
-	hpriv->fd = open(filename, O_RDWR);
-	if (hpriv->fd < 0) {
-		if (errno == EACCES) {
-			usbi_err(HANDLE_CTX(handle), "libusb couldn't open USB device %s: "
-				"Permission denied.", filename);
-			usbi_err(HANDLE_CTX(handle),
-				"libusb requires write access to USB device nodes.");
-			return LIBUSB_ERROR_ACCESS;
-		} else if (errno == ENOENT) {
-			usbi_err(HANDLE_CTX(handle), "libusb couldn't open USB device %s: "
-				"No such file or directory.", filename);
-			return LIBUSB_ERROR_NO_DEVICE;
-		} else {
-			usbi_err(HANDLE_CTX(handle),
-				"open failed, code %d errno %d", hpriv->fd, errno);
-			return LIBUSB_ERROR_IO;
-		}
-	}
-
-	return usbi_add_pollfd(HANDLE_CTX(handle), hpriv->fd, POLLOUT);
-}
-
-static void op_close(struct libusb_device_handle *dev_handle)
-{
-	int fd = _device_handle_priv(dev_handle)->fd;
-	usbi_remove_pollfd(HANDLE_CTX(dev_handle), fd);
-	close(fd);
-}
-
-static int op_get_configuration(struct libusb_device_handle *handle,
-	int *config)
-{
-	int r;
-	if (sysfs_can_relate_devices != 1)
-		return LIBUSB_ERROR_NOT_SUPPORTED;
-
-	r = sysfs_get_active_config(handle->dev, config);
-	if (r < 0)
-		return r;
-
-	if (*config == -1)
-		*config = 0;
-
-	return 0;
-}
-
-static int op_set_configuration(struct libusb_device_handle *handle, int config)
-{
-	struct linux_device_priv *priv = _device_priv(handle->dev);
-	int fd = _device_handle_priv(handle)->fd;
-	int r = ioctl(fd, IOCTL_USBFS_SETCONFIG, &config);
-	if (r) {
-		if (errno == EINVAL)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == EBUSY)
-			return LIBUSB_ERROR_BUSY;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle), "failed, error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	if (!sysfs_has_descriptors) {
-		/* update our cached active config descriptor */
-		if (config == -1) {
-			if (priv->config_descriptor) {
-				free(priv->config_descriptor);
-				priv->config_descriptor = NULL;
-			}
-		} else {
-			r = cache_active_config(handle->dev, fd, config);
-			if (r < 0)
-				usbi_warn(HANDLE_CTX(handle),
-					"failed to update cached config descriptor, error %d", r);
-		}
-	}
-
-	return 0;
-}
-
-static int op_claim_interface(struct libusb_device_handle *handle, int iface)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	int r = ioctl(fd, IOCTL_USBFS_CLAIMINTF, &iface);
-	if (r) {
-		if (errno == ENOENT)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == EBUSY)
-			return LIBUSB_ERROR_BUSY;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"claim interface failed, error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-	return 0;
-}
-
-static int op_release_interface(struct libusb_device_handle *handle, int iface)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	int r = ioctl(fd, IOCTL_USBFS_RELEASEINTF, &iface);
-	if (r) {
-		if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"release interface failed, error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-	return 0;
-}
-
-static int op_set_interface(struct libusb_device_handle *handle, int iface,
-	int altsetting)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	struct usbfs_setinterface setintf;
-	int r;
-
-	setintf.interface = iface;
-	setintf.altsetting = altsetting;
-	r = ioctl(fd, IOCTL_USBFS_SETINTF, &setintf);
-	if (r) {
-		if (errno == EINVAL)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"setintf failed error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	return 0;
-}
-
-static int op_clear_halt(struct libusb_device_handle *handle,
-	unsigned char endpoint)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	unsigned int _endpoint = endpoint;
-	int r = ioctl(fd, IOCTL_USBFS_CLEAR_HALT, &_endpoint);
-	if (r) {
-		if (errno == ENOENT)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"clear_halt failed error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	return 0;
-}
-
-static int op_reset_device(struct libusb_device_handle *handle)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	int i, r, ret = 0;
-
-	/* Doing a device reset will cause the usbfs driver to get unbound
-	   from any interfaces it is bound to. By voluntarily unbinding
-	   the usbfs driver ourself, we stop the kernel from rebinding
-	   the interface after reset (which would end up with the interface
-	   getting bound to the in kernel driver if any). */
-	for (i = 0; i < USB_MAXINTERFACES; i++) {
-		if (handle->claimed_interfaces & (1L << i)) {
-			op_release_interface(handle, i);
-		}
-	}
-
-	usbi_mutex_lock(&handle->lock);
-	r = ioctl(fd, IOCTL_USBFS_RESET, NULL);
-	if (r) {
-		if (errno == ENODEV) {
-			ret = LIBUSB_ERROR_NOT_FOUND;
-			goto out;
-		}
-
-		usbi_err(HANDLE_CTX(handle),
-			"reset failed error %d errno %d", r, errno);
-		ret = LIBUSB_ERROR_OTHER;
-		goto out;
-	}
-
-	/* And re-claim any interfaces which were claimed before the reset */
-	for (i = 0; i < USB_MAXINTERFACES; i++) {
-		if (handle->claimed_interfaces & (1L << i)) {
-			r = op_claim_interface(handle, i);
-			if (r) {
-				usbi_warn(HANDLE_CTX(handle),
-					"failed to re-claim interface %d after reset", i);
-				handle->claimed_interfaces &= ~(1L << i);
-			}
-		}
-	}
-out:
-	usbi_mutex_unlock(&handle->lock);
-	return ret;
-}
-
-static int op_kernel_driver_active(struct libusb_device_handle *handle,
-	int interface)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	struct usbfs_getdriver getdrv;
-	int r;
-
-	getdrv.interface = interface;
-	r = ioctl(fd, IOCTL_USBFS_GETDRIVER, &getdrv);
-	if (r) {
-		if (errno == ENODATA)
-			return 0;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"get driver failed error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	return 1;
-}
-
-static int op_detach_kernel_driver(struct libusb_device_handle *handle,
-	int interface)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	struct usbfs_ioctl command;
-	int r;
-
-	command.ifno = interface;
-	command.ioctl_code = IOCTL_USBFS_DISCONNECT;
-	command.data = NULL;
-
-	r = ioctl(fd, IOCTL_USBFS_IOCTL, &command);
-	if (r) {
-		if (errno == ENODATA)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == EINVAL)
-			return LIBUSB_ERROR_INVALID_PARAM;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle),
-			"detach failed error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	}
-
-	return 0;
-}
-
-static int op_attach_kernel_driver(struct libusb_device_handle *handle,
-	int interface)
-{
-	int fd = _device_handle_priv(handle)->fd;
-	struct usbfs_ioctl command;
-	int r;
-
-	command.ifno = interface;
-	command.ioctl_code = IOCTL_USBFS_CONNECT;
-	command.data = NULL;
-
-	r = ioctl(fd, IOCTL_USBFS_IOCTL, &command);
-	if (r < 0) {
-		if (errno == ENODATA)
-			return LIBUSB_ERROR_NOT_FOUND;
-		else if (errno == EINVAL)
-			return LIBUSB_ERROR_INVALID_PARAM;
-		else if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-		else if (errno == EBUSY)
-			return LIBUSB_ERROR_BUSY;
-
-		usbi_err(HANDLE_CTX(handle),
-			"attach failed error %d errno %d", r, errno);
-		return LIBUSB_ERROR_OTHER;
-	} else if (r == 0) {
-		return LIBUSB_ERROR_NOT_FOUND;
-	}
-
-	return 0;
-}
-
-static void op_destroy_device(struct libusb_device *dev)
-{
-	struct linux_device_priv *priv = _device_priv(dev);
-	if (!sysfs_has_descriptors) {
-		if (priv->dev_descriptor)
-			free(priv->dev_descriptor);
-		if (priv->config_descriptor)
-			free(priv->config_descriptor);
-	}
-	if (priv->sysfs_dir)
-		free(priv->sysfs_dir);
-}
-
-/* URBs are discarded in reverse order of submission to avoid races. */
-static int discard_urbs(struct usbi_transfer *itransfer, int first, int last_plus_one)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_transfer_priv *tpriv =
-		usbi_transfer_get_os_priv(itransfer);
-	struct linux_device_handle_priv *dpriv =
-		_device_handle_priv(transfer->dev_handle);
-	int i, ret = 0;
-	struct usbfs_urb *urb;
-
-	for (i = last_plus_one - 1; i >= first; i--) {
-		if (LIBUSB_TRANSFER_TYPE_ISOCHRONOUS == transfer->type)
-			urb = tpriv->iso_urbs[i];
-		else
-			urb = &tpriv->urbs[i];
-
-		if (0 == ioctl(dpriv->fd, IOCTL_USBFS_DISCARDURB, urb))
-			continue;
-
-		if (EINVAL == errno) {
-			usbi_dbg("URB not found --> assuming ready to be reaped");
-			ret = LIBUSB_ERROR_NOT_FOUND;
-		} else if (ENODEV == errno) {
-			usbi_dbg("Device not found for URB --> assuming ready to be reaped");
-			ret = LIBUSB_ERROR_NO_DEVICE;
-		} else {
-			usbi_warn(TRANSFER_CTX(transfer),
-				"unrecognised discard errno %d", errno);
-			ret = LIBUSB_ERROR_OTHER;
-		}
-	}
-	return ret;
-}
-
-static void free_iso_urbs(struct linux_transfer_priv *tpriv)
-{
-	int i;
-	for (i = 0; i < tpriv->num_urbs; i++) {
-		struct usbfs_urb *urb = tpriv->iso_urbs[i];
-		if (!urb)
-			break;
-		free(urb);
-	}
-
-	free(tpriv->iso_urbs);
-	tpriv->iso_urbs = NULL;
-}
-
-static int submit_bulk_transfer(struct usbi_transfer *itransfer,
-	unsigned char urb_type)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	struct linux_device_handle_priv *dpriv =
-		_device_handle_priv(transfer->dev_handle);
-	struct usbfs_urb *urbs;
-	int is_out = (transfer->endpoint & LIBUSB_ENDPOINT_DIR_MASK)
-		== LIBUSB_ENDPOINT_OUT;
-	int r;
-	int i;
-	size_t alloc_size;
-
-	if (tpriv->urbs)
-		return LIBUSB_ERROR_BUSY;
-
-	/* usbfs places a 16kb limit on bulk URBs. we divide up larger requests
-	 * into smaller units to meet such restriction, then fire off all the
-	 * units at once. it would be simpler if we just fired one unit at a time,
-	 * but there is a big performance gain through doing it this way. */
-	int num_urbs = transfer->length / MAX_BULK_BUFFER_LENGTH;
-	int last_urb_partial = 0;
-
-	if (transfer->length == 0) {
-		num_urbs = 1;
-	} else if ((transfer->length % MAX_BULK_BUFFER_LENGTH) > 0) {
-		last_urb_partial = 1;
-		num_urbs++;
-	}
-	usbi_dbg("need %d urbs for new transfer with length %d", num_urbs,
-		transfer->length);
-	alloc_size = num_urbs * sizeof(struct usbfs_urb);
-	urbs = malloc(alloc_size);
-	if (!urbs)
-		return LIBUSB_ERROR_NO_MEM;
-	memset(urbs, 0, alloc_size);
-	tpriv->urbs = urbs;
-	tpriv->num_urbs = num_urbs;
-	tpriv->num_retired = 0;
-	tpriv->reap_action = NORMAL;
-	tpriv->reap_status = LIBUSB_TRANSFER_COMPLETED;
-
-	for (i = 0; i < num_urbs; i++) {
-		struct usbfs_urb *urb = &urbs[i];
-		urb->usercontext = itransfer;
-		urb->type = urb_type;
-		urb->endpoint = transfer->endpoint;
-		urb->buffer = transfer->buffer + (i * MAX_BULK_BUFFER_LENGTH);
-		if (supports_flag_bulk_continuation && !is_out)
-			urb->flags = USBFS_URB_SHORT_NOT_OK;
-		if (i == num_urbs - 1 && last_urb_partial)
-			urb->buffer_length = transfer->length % MAX_BULK_BUFFER_LENGTH;
-		else if (transfer->length == 0)
-			urb->buffer_length = 0;
-		else
-			urb->buffer_length = MAX_BULK_BUFFER_LENGTH;
-
-		if (i > 0 && supports_flag_bulk_continuation)
-			urb->flags |= USBFS_URB_BULK_CONTINUATION;
-
-		r = ioctl(dpriv->fd, IOCTL_USBFS_SUBMITURB, urb);
-		if (r < 0) {
-			if (errno == ENODEV) {
-				r = LIBUSB_ERROR_NO_DEVICE;
-			} else {
-				usbi_err(TRANSFER_CTX(transfer),
-					"submiturb failed error %d errno=%d", r, errno);
-				r = LIBUSB_ERROR_IO;
-			}
-	
-			/* if the first URB submission fails, we can simply free up and
-			 * return failure immediately. */
-			if (i == 0) {
-				usbi_dbg("first URB failed, easy peasy");
-				free(urbs);
-				tpriv->urbs = NULL;
-				return r;
-			}
-
-			/* if it's not the first URB that failed, the situation is a bit
-			 * tricky. we may need to discard all previous URBs. there are
-			 * complications:
-			 *  - discarding is asynchronous - discarded urbs will be reaped
-			 *    later. the user must not have freed the transfer when the
-			 *    discarded URBs are reaped, otherwise libusb will be using
-			 *    freed memory.
-			 *  - the earlier URBs may have completed successfully and we do
-			 *    not want to throw away any data.
-			 *  - this URB failing may be no error; EREMOTEIO means that
-			 *    this transfer simply didn't need all the URBs we submitted
-			 * so, we report that the transfer was submitted successfully and
-			 * in case of error we discard all previous URBs. later when
-			 * the final reap completes we can report error to the user,
-			 * or success if an earlier URB was completed successfully.
-			 */
-			tpriv->reap_action = EREMOTEIO == errno ? COMPLETED_EARLY : SUBMIT_FAILED;
-
-			/* The URBs we haven't submitted yet we count as already
-			 * retired. */
-			tpriv->num_retired += num_urbs - i;
-
-			/* If we completed short then don't try to discard. */
-			if (COMPLETED_EARLY == tpriv->reap_action)
-				return 0;
-
-			discard_urbs(itransfer, 0, i);
-
-			usbi_dbg("reporting successful submission but waiting for %d "
-				"discards before reporting error", i);
-			return 0;
-		}
-	}
-
-	return 0;
-}
-
-static int submit_iso_transfer(struct usbi_transfer *itransfer)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	struct linux_device_handle_priv *dpriv =
-		_device_handle_priv(transfer->dev_handle);
-	struct usbfs_urb **urbs;
-	size_t alloc_size;
-	int num_packets = transfer->num_iso_packets;
-	int i;
-	int this_urb_len = 0;
-	int num_urbs = 1;
-	int packet_offset = 0;
-	unsigned int packet_len;
-	unsigned char *urb_buffer = transfer->buffer;
-
-	if (tpriv->iso_urbs)
-		return LIBUSB_ERROR_BUSY;
-
-	/* usbfs places a 32kb limit on iso URBs. we divide up larger requests
-	 * into smaller units to meet such restriction, then fire off all the
-	 * units at once. it would be simpler if we just fired one unit at a time,
-	 * but there is a big performance gain through doing it this way. */
-
-	/* calculate how many URBs we need */
-	for (i = 0; i < num_packets; i++) {
-		int space_remaining = MAX_ISO_BUFFER_LENGTH - this_urb_len;
-		packet_len = transfer->iso_packet_desc[i].length;
-
-		if (packet_len > space_remaining) {
-			num_urbs++;
-			this_urb_len = packet_len;
-		} else {
-			this_urb_len += packet_len;
-		}
-	}
-	usbi_dbg("need %d 32k URBs for transfer", num_urbs);
-
-	alloc_size = num_urbs * sizeof(*urbs);
-	urbs = malloc(alloc_size);
-	if (!urbs)
-		return LIBUSB_ERROR_NO_MEM;
-	memset(urbs, 0, alloc_size);
-
-	tpriv->iso_urbs = urbs;
-	tpriv->num_urbs = num_urbs;
-	tpriv->num_retired = 0;
-	tpriv->reap_action = NORMAL;
-	tpriv->iso_packet_offset = 0;
-
-	/* allocate + initialize each URB with the correct number of packets */
-	for (i = 0; i < num_urbs; i++) {
-		struct usbfs_urb *urb;
-		int space_remaining_in_urb = MAX_ISO_BUFFER_LENGTH;
-		int urb_packet_offset = 0;
-		unsigned char *urb_buffer_orig = urb_buffer;
-		int j;
-		int k;
-
-		/* swallow up all the packets we can fit into this URB */
-		while (packet_offset < transfer->num_iso_packets) {
-			packet_len = transfer->iso_packet_desc[packet_offset].length;
-			if (packet_len <= space_remaining_in_urb) {
-				/* throw it in */
-				urb_packet_offset++;
-				packet_offset++;
-				space_remaining_in_urb -= packet_len;
-				urb_buffer += packet_len;
-			} else {
-				/* it can't fit, save it for the next URB */
-				break;
-			}
-		}
-
-		alloc_size = sizeof(*urb)
-			+ (urb_packet_offset * sizeof(struct usbfs_iso_packet_desc));
-		urb = malloc(alloc_size);
-		if (!urb) {
-			free_iso_urbs(tpriv);
-			return LIBUSB_ERROR_NO_MEM;
-		}
-		memset(urb, 0, alloc_size);
-		urbs[i] = urb;
-
-		/* populate packet lengths */
-		for (j = 0, k = packet_offset - urb_packet_offset;
-				k < packet_offset; k++, j++) {
-			packet_len = transfer->iso_packet_desc[k].length;
-			urb->iso_frame_desc[j].length = packet_len;
-		}
-
-		urb->usercontext = itransfer;
-		urb->type = USBFS_URB_TYPE_ISO;
-		/* FIXME: interface for non-ASAP data? */
-		urb->flags = USBFS_URB_ISO_ASAP;
-		urb->endpoint = transfer->endpoint;
-		urb->number_of_packets = urb_packet_offset;
-		urb->buffer = urb_buffer_orig;
-	}
-
-	/* submit URBs */
-	for (i = 0; i < num_urbs; i++) {
-		int r = ioctl(dpriv->fd, IOCTL_USBFS_SUBMITURB, urbs[i]);
-		if (r < 0) {
-			if (errno == ENODEV) {
-				r = LIBUSB_ERROR_NO_DEVICE;
-			} else {
-				usbi_err(TRANSFER_CTX(transfer),
-					"submiturb failed error %d errno=%d", r, errno);
-				r = LIBUSB_ERROR_IO;
-			}
-
-			/* if the first URB submission fails, we can simply free up and
-			 * return failure immediately. */
-			if (i == 0) {
-				usbi_dbg("first URB failed, easy peasy");
-				free_iso_urbs(tpriv);
-				return r;
-			}
-
-			/* if it's not the first URB that failed, the situation is a bit
-			 * tricky. we must discard all previous URBs. there are
-			 * complications:
-			 *  - discarding is asynchronous - discarded urbs will be reaped
-			 *    later. the user must not have freed the transfer when the
-			 *    discarded URBs are reaped, otherwise libusb will be using
-			 *    freed memory.
-			 *  - the earlier URBs may have completed successfully and we do
-			 *    not want to throw away any data.
-			 * so, in this case we discard all the previous URBs BUT we report
-			 * that the transfer was submitted successfully. then later when
-			 * the final discard completes we can report error to the user.
-			 */
-			tpriv->reap_action = SUBMIT_FAILED;
-
-			/* The URBs we haven't submitted yet we count as already
-			 * retired. */
-			tpriv->num_retired = num_urbs - i;
-			discard_urbs(itransfer, 0, i);
-
-			usbi_dbg("reporting successful submission but waiting for %d "
-				"discards before reporting error", i);
-			return 0;
-		}
-	}
-
-	return 0;
-}
-
-static int submit_control_transfer(struct usbi_transfer *itransfer)
-{
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_device_handle_priv *dpriv =
-		_device_handle_priv(transfer->dev_handle);
-	struct usbfs_urb *urb;
-	int r;
-
-	if (tpriv->urbs)
-		return LIBUSB_ERROR_BUSY;
-
-	if (transfer->length - LIBUSB_CONTROL_SETUP_SIZE > MAX_CTRL_BUFFER_LENGTH)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
-	urb = malloc(sizeof(struct usbfs_urb));
-	if (!urb)
-		return LIBUSB_ERROR_NO_MEM;
-	memset(urb, 0, sizeof(struct usbfs_urb));
-	tpriv->urbs = urb;
-	tpriv->num_urbs = 1;
-	tpriv->reap_action = NORMAL;
-
-	urb->usercontext = itransfer;
-	urb->type = USBFS_URB_TYPE_CONTROL;
-	urb->endpoint = transfer->endpoint;
-	urb->buffer = transfer->buffer;
-	urb->buffer_length = transfer->length;
-
-	r = ioctl(dpriv->fd, IOCTL_USBFS_SUBMITURB, urb);
-	if (r < 0) {
-		free(urb);
-		tpriv->urbs = NULL;
-		if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(TRANSFER_CTX(transfer),
-			"submiturb failed error %d errno=%d", r, errno);
-		return LIBUSB_ERROR_IO;
-	}
-	return 0;
-}
-
-static int op_submit_transfer(struct usbi_transfer *itransfer)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-
-	switch (transfer->type) {
-	case LIBUSB_TRANSFER_TYPE_CONTROL:
-		return submit_control_transfer(itransfer);
-	case LIBUSB_TRANSFER_TYPE_BULK:
-		return submit_bulk_transfer(itransfer, USBFS_URB_TYPE_BULK);
-	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
-		return submit_bulk_transfer(itransfer, USBFS_URB_TYPE_INTERRUPT);
-	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
-		return submit_iso_transfer(itransfer);
-	default:
-		usbi_err(TRANSFER_CTX(transfer),
-			"unknown endpoint type %d", transfer->type);
-		return LIBUSB_ERROR_INVALID_PARAM;
-	}
-}
-
-static int op_cancel_transfer(struct usbi_transfer *itransfer)
-{
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-
-	switch (transfer->type) {
-	case LIBUSB_TRANSFER_TYPE_BULK:
-		if (tpriv->reap_action == ERROR)
-			break;
-		/* else, fall through */
-	case LIBUSB_TRANSFER_TYPE_CONTROL:
-	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
-	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
-		tpriv->reap_action = CANCELLED;
-		break;
-	default:
-		usbi_err(TRANSFER_CTX(transfer),
-			"unknown endpoint type %d", transfer->type);
-		return LIBUSB_ERROR_INVALID_PARAM;
-	}
-
-	if (!tpriv->urbs)
-		return LIBUSB_ERROR_NOT_FOUND;
-
-	return discard_urbs(itransfer, 0, tpriv->num_urbs);
-}
-
-static void op_clear_transfer_priv(struct usbi_transfer *itransfer)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-
-	/* urbs can be freed also in submit_transfer so lock mutex first */
-	switch (transfer->type) {
-	case LIBUSB_TRANSFER_TYPE_CONTROL:
-	case LIBUSB_TRANSFER_TYPE_BULK:
-	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
-		usbi_mutex_lock(&itransfer->lock);
-		if (tpriv->urbs)
-			free(tpriv->urbs);
-		tpriv->urbs = NULL;
-		usbi_mutex_unlock(&itransfer->lock);
-		break;
-	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
-		usbi_mutex_lock(&itransfer->lock);
-		if (tpriv->iso_urbs)
-			free_iso_urbs(tpriv);
-		usbi_mutex_unlock(&itransfer->lock);
-		break;
-	default:
-		usbi_err(TRANSFER_CTX(transfer),
-			"unknown endpoint type %d", transfer->type);
-	}
-}
-
-static int handle_bulk_completion(struct usbi_transfer *itransfer,
-	struct usbfs_urb *urb)
-{
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	int urb_idx = urb - tpriv->urbs;
-
-	usbi_mutex_lock(&itransfer->lock);
-	usbi_dbg("handling completion status %d of bulk urb %d/%d", urb->status,
-		urb_idx + 1, tpriv->num_urbs);
-
-	tpriv->num_retired++;
-
-	if (tpriv->reap_action != NORMAL) {
-		/* cancelled, submit_fail, or completed early */
-		usbi_dbg("abnormal reap: urb status %d", urb->status);
-
-		/* even though we're in the process of cancelling, it's possible that
-		 * we may receive some data in these URBs that we don't want to lose.
-		 * examples:
-		 * 1. while the kernel is cancelling all the packets that make up an
-		 *    URB, a few of them might complete. so we get back a successful
-		 *    cancellation *and* some data.
-		 * 2. we receive a short URB which marks the early completion condition,
-		 *    so we start cancelling the remaining URBs. however, we're too
-		 *    slow and another URB completes (or at least completes partially).
-		 *    (this can't happen since we always use BULK_CONTINUATION.)
-		 *
-		 * When this happens, our objectives are not to lose any "surplus" data,
-		 * and also to stick it at the end of the previously-received data
-		 * (closing any holes), so that libusb reports the total amount of
-		 * transferred data and presents it in a contiguous chunk.
-		 */
-		if (urb->actual_length > 0) {
-			unsigned char *target = transfer->buffer + itransfer->transferred;
-			usbi_dbg("received %d bytes of surplus data", urb->actual_length);
-			if (urb->buffer != target) {
-				usbi_dbg("moving surplus data from offset %d to offset %d",
-					(unsigned char *) urb->buffer - transfer->buffer,
-					target - transfer->buffer);
-				memmove(target, urb->buffer, urb->actual_length);
-			}
-			itransfer->transferred += urb->actual_length;
-		}
-
-		if (tpriv->num_retired == tpriv->num_urbs) {
-			usbi_dbg("abnormal reap: last URB handled, reporting");
-			if (tpriv->reap_action != COMPLETED_EARLY &&
-			    tpriv->reap_status == LIBUSB_TRANSFER_COMPLETED)
-				tpriv->reap_status = LIBUSB_TRANSFER_ERROR;
-			goto completed;
-		}
-		goto out_unlock;
-	}
-
-	itransfer->transferred += urb->actual_length;
-
-	/* Many of these errors can occur on *any* urb of a multi-urb
-	 * transfer.  When they do, we tear down the rest of the transfer.
-	 */
-	switch (urb->status) {
-	case 0:
-		break;
-	case -EREMOTEIO: /* short transfer */
-		break;
-	case -ENOENT: /* cancelled */
-	case -ECONNRESET:
-		break;
-	case -ESHUTDOWN:
-		usbi_dbg("device removed");
-		tpriv->reap_status = LIBUSB_TRANSFER_NO_DEVICE;
-		goto cancel_remaining;
-	case -EPIPE:
-		usbi_dbg("detected endpoint stall");
-		if (tpriv->reap_status == LIBUSB_TRANSFER_COMPLETED)
-			tpriv->reap_status = LIBUSB_TRANSFER_STALL;
-		goto cancel_remaining;
-	case -EOVERFLOW:
-		/* overflow can only ever occur in the last urb */
-		usbi_dbg("overflow, actual_length=%d", urb->actual_length);
-		if (tpriv->reap_status == LIBUSB_TRANSFER_COMPLETED)
-			tpriv->reap_status = LIBUSB_TRANSFER_OVERFLOW;
-		goto completed;
-	case -ETIME:
-	case -EPROTO:
-	case -EILSEQ:
-		usbi_dbg("low level error %d", urb->status);
-		tpriv->reap_action = ERROR;
-		goto cancel_remaining;
-	default:
-		usbi_warn(ITRANSFER_CTX(itransfer),
-			"unrecognised urb status %d", urb->status);
-		tpriv->reap_action = ERROR;
-		goto cancel_remaining;
-	}
-
-	/* if we're the last urb or we got less data than requested then we're
-	 * done */
-	if (urb_idx == tpriv->num_urbs - 1) {
-		usbi_dbg("last URB in transfer --> complete!");
-		goto completed;
-	} else if (urb->actual_length < urb->buffer_length) {
-		usbi_dbg("short transfer %d/%d --> complete!",
-			urb->actual_length, urb->buffer_length);
-		if (tpriv->reap_action == NORMAL)
-			tpriv->reap_action = COMPLETED_EARLY;
-	} else
-		goto out_unlock;
-
-cancel_remaining:
-	if (ERROR == tpriv->reap_action && LIBUSB_TRANSFER_COMPLETED == tpriv->reap_status)
-		tpriv->reap_status = LIBUSB_TRANSFER_ERROR;
-
-	if (tpriv->num_retired == tpriv->num_urbs) /* nothing to cancel */
-		goto completed;
-
-	/* cancel remaining urbs and wait for their completion before
-	 * reporting results */
-	discard_urbs(itransfer, urb_idx + 1, tpriv->num_urbs);
-
-out_unlock:
-	usbi_mutex_unlock(&itransfer->lock);
-	return 0;
-
-completed:
-	free(tpriv->urbs);
-	tpriv->urbs = NULL;
-	usbi_mutex_unlock(&itransfer->lock);
-	return CANCELLED == tpriv->reap_action ?
-		usbi_handle_transfer_cancellation(itransfer) :
-		usbi_handle_transfer_completion(itransfer, tpriv->reap_status);
-}
-
-static int handle_iso_completion(struct usbi_transfer *itransfer,
-	struct usbfs_urb *urb)
-{
-	struct libusb_transfer *transfer =
-		USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	int num_urbs = tpriv->num_urbs;
-	int urb_idx = 0;
-	int i;
-	enum libusb_transfer_status status = LIBUSB_TRANSFER_COMPLETED;
-
-	usbi_mutex_lock(&itransfer->lock);
-	for (i = 0; i < num_urbs; i++) {
-		if (urb == tpriv->iso_urbs[i]) {
-			urb_idx = i + 1;
-			break;
-		}
-	}
-	if (urb_idx == 0) {
-		usbi_err(TRANSFER_CTX(transfer), "could not locate urb!");
-		usbi_mutex_unlock(&itransfer->lock);
-		return LIBUSB_ERROR_NOT_FOUND;
-	}
-
-	usbi_dbg("handling completion status %d of iso urb %d/%d", urb->status,
-		urb_idx, num_urbs);
-
-	/* copy isochronous results back in */
-
-	for (i = 0; i < urb->number_of_packets; i++) {
-		struct usbfs_iso_packet_desc *urb_desc = &urb->iso_frame_desc[i];
-		struct libusb_iso_packet_descriptor *lib_desc =
-			&transfer->iso_packet_desc[tpriv->iso_packet_offset++];
-		lib_desc->status = urb_desc->status;
-		lib_desc->actual_length = urb_desc->actual_length;
-	}
-
-	tpriv->num_retired++;
-
-	if (tpriv->reap_action != NORMAL) { /* cancelled or submit_fail */
-		usbi_dbg("CANCEL: urb status %d", urb->status);
-
-		if (status == LIBUSB_TRANSFER_COMPLETED)
-			status = LIBUSB_TRANSFER_ERROR;
-
-		if (tpriv->num_retired == num_urbs) {
-			usbi_dbg("CANCEL: last URB handled, reporting");
-			free_iso_urbs(tpriv);
-			if (tpriv->reap_action == CANCELLED) {
-				usbi_mutex_unlock(&itransfer->lock);
-				return usbi_handle_transfer_cancellation(itransfer);
-			} else {
-				usbi_mutex_unlock(&itransfer->lock);
-				return usbi_handle_transfer_completion(itransfer,
-					LIBUSB_TRANSFER_ERROR);
-			}
-		}
-		goto out;
-	}
-
-	switch (urb->status) {
-	case 0:
-		break;
-	case -ENOENT: /* cancelled */
-		break;
-	case -ESHUTDOWN:
-		usbi_dbg("device removed");
-		status = LIBUSB_TRANSFER_NO_DEVICE;
-		break;
-	case -ETIME:
-	case -EPROTO:
-	case -EILSEQ:
-		usbi_dbg("low-level USB error %d", urb->status);
-		break;
-	default:
-		usbi_warn(TRANSFER_CTX(transfer),
-			"unrecognised urb status %d", urb->status);
-		break;
-	}
-
-	/* if we're the last urb or we got less data than requested then we're
-	 * done */
-	if (urb_idx == num_urbs) {
-		usbi_dbg("last URB in transfer --> complete!");
-		free_iso_urbs(tpriv);
-		usbi_mutex_unlock(&itransfer->lock);
-		return usbi_handle_transfer_completion(itransfer, status);
-	}
-
-out:
-	usbi_mutex_unlock(&itransfer->lock);
-	return 0;
-}
-
-static int handle_control_completion(struct usbi_transfer *itransfer,
-	struct usbfs_urb *urb)
-{
-	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
-	int status;
-
-	usbi_mutex_lock(&itransfer->lock);
-	usbi_dbg("handling completion status %d", urb->status);
-
-	itransfer->transferred += urb->actual_length;
-
-	if (tpriv->reap_action == CANCELLED) {
-		if (urb->status != 0 && urb->status != -ENOENT)
-			usbi_warn(ITRANSFER_CTX(itransfer),
-				"cancel: unrecognised urb status %d", urb->status);
-		free(tpriv->urbs);
-		tpriv->urbs = NULL;
-		usbi_mutex_unlock(&itransfer->lock);
-		return usbi_handle_transfer_cancellation(itransfer);
-	}
-
-	switch (urb->status) {
-	case 0:
-		status = LIBUSB_TRANSFER_COMPLETED;
-		break;
-	case -ENOENT: /* cancelled */
-		status = LIBUSB_TRANSFER_CANCELLED;
-		break;
-	case -ESHUTDOWN:
-		usbi_dbg("device removed");
-		status = LIBUSB_TRANSFER_NO_DEVICE;
-		break;
-	case -EPIPE:
-		usbi_dbg("unsupported control request");
-		status = LIBUSB_TRANSFER_STALL;
-		break;
-	case -ETIME:
-	case -EPROTO:
-	case -EILSEQ:
-		usbi_dbg("low-level bus error occurred");
-		status = LIBUSB_TRANSFER_ERROR;
-		break;
-	default:
-		usbi_warn(ITRANSFER_CTX(itransfer),
-			"unrecognised urb status %d", urb->status);
-		status = LIBUSB_TRANSFER_ERROR;
-		break;
-	}
-
-	free(tpriv->urbs);
-	tpriv->urbs = NULL;
-	usbi_mutex_unlock(&itransfer->lock);
-	return usbi_handle_transfer_completion(itransfer, status);
-}
-
-static int reap_for_handle(struct libusb_device_handle *handle)
-{
-	struct linux_device_handle_priv *hpriv = _device_handle_priv(handle);
-	int r;
-	struct usbfs_urb *urb;
-	struct usbi_transfer *itransfer;
-	struct libusb_transfer *transfer;
-
-	r = ioctl(hpriv->fd, IOCTL_USBFS_REAPURBNDELAY, &urb);
-	if (r == -1 && errno == EAGAIN)
-		return 1;
-	if (r < 0) {
-		if (errno == ENODEV)
-			return LIBUSB_ERROR_NO_DEVICE;
-
-		usbi_err(HANDLE_CTX(handle), "reap failed error %d errno=%d",
-			r, errno);
-		return LIBUSB_ERROR_IO;
-	}
-
-	itransfer = urb->usercontext;
-	transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-
-	usbi_dbg("urb type=%d status=%d transferred=%d", urb->type, urb->status,
-		urb->actual_length);
-
-	switch (transfer->type) {
-	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
-		return handle_iso_completion(itransfer, urb);
-	case LIBUSB_TRANSFER_TYPE_BULK:
-	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
-		return handle_bulk_completion(itransfer, urb);
-	case LIBUSB_TRANSFER_TYPE_CONTROL:
-		return handle_control_completion(itransfer, urb);
-	default:
-		usbi_err(HANDLE_CTX(handle), "unrecognised endpoint type %x",
-			transfer->type);
-		return LIBUSB_ERROR_OTHER;
-	}
-}
-
-static int op_handle_events(struct libusb_context *ctx,
-	struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready)
-{
-	int r;
-	int i = 0;
-
-	usbi_mutex_lock(&ctx->open_devs_lock);
-	for (i = 0; i < nfds && num_ready > 0; i++) {
-		struct pollfd *pollfd = &fds[i];
-		struct libusb_device_handle *handle;
-		struct linux_device_handle_priv *hpriv = NULL;
-
-		if (!pollfd->revents)
-			continue;
-
-		num_ready--;
-		list_for_each_entry(handle, &ctx->open_devs, list, struct libusb_device_handle) {
-			hpriv = _device_handle_priv(handle);
-			if (hpriv->fd == pollfd->fd)
-				break;
-		}
-
-		if (pollfd->revents & POLLERR) {
-			usbi_remove_pollfd(HANDLE_CTX(handle), hpriv->fd);
-			usbi_handle_disconnect(handle);
-			continue;
-		}
-
-		r = reap_for_handle(handle);
-		if (r == 1 || r == LIBUSB_ERROR_NO_DEVICE)
-			continue;
-		else if (r < 0)
-			goto out;
-	}
-
-	r = 0;
-out:
-	usbi_mutex_unlock(&ctx->open_devs_lock);
-	return r;
-}
-
-static int op_clock_gettime(int clk_id, struct timespec *tp)
-{
-	switch (clk_id) {
-	case USBI_CLOCK_MONOTONIC:
-		return clock_gettime(monotonic_clkid, tp);
-	case USBI_CLOCK_REALTIME:
-		return clock_gettime(CLOCK_REALTIME, tp);
-	default:
-		return LIBUSB_ERROR_INVALID_PARAM;
-  }
-}
-
-#ifdef USBI_TIMERFD_AVAILABLE
-static clockid_t op_get_timerfd_clockid(void)
-{
-	return monotonic_clkid;
-
-}
-#endif
-
-const struct usbi_os_backend linux_usbfs_backend = {
-	.name = "Linux usbfs",
-	.init = op_init,
-	.exit = NULL,
-	.get_device_list = op_get_device_list,
-	.get_device_descriptor = op_get_device_descriptor,
-	.get_active_config_descriptor = op_get_active_config_descriptor,
-	.get_config_descriptor = op_get_config_descriptor,
-
-	.open = op_open,
-	.close = op_close,
-	.get_configuration = op_get_configuration,
-	.set_configuration = op_set_configuration,
-	.claim_interface = op_claim_interface,
-	.release_interface = op_release_interface,
-
-	.set_interface_altsetting = op_set_interface,
-	.clear_halt = op_clear_halt,
-	.reset_device = op_reset_device,
-
-	.kernel_driver_active = op_kernel_driver_active,
-	.detach_kernel_driver = op_detach_kernel_driver,
-	.attach_kernel_driver = op_attach_kernel_driver,
-
-	.destroy_device = op_destroy_device,
-
-	.submit_transfer = op_submit_transfer,
-	.cancel_transfer = op_cancel_transfer,
-	.clear_transfer_priv = op_clear_transfer_priv,
-
-	.handle_events = op_handle_events,
-
-	.clock_gettime = op_clock_gettime,
-
-#ifdef USBI_TIMERFD_AVAILABLE
-	.get_timerfd_clockid = op_get_timerfd_clockid,
-#endif
-
-	.device_priv_size = sizeof(struct linux_device_priv),
-	.device_handle_priv_size = sizeof(struct linux_device_handle_priv),
-	.transfer_priv_size = sizeof(struct linux_transfer_priv),
-	.add_iso_packet_size = 0,
-};
-