linux_usbfs.c

最新的libusb库

	}

	r = get_config_descriptor(DEVICE_CTX(dev), fd, config_index, buffer, len);
	close(fd);
	*host_endian = 1;
	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, 1);
	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)
{
	int active_config;
	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;

		usbi_err(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;
	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);
	}

	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 < 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("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 = 0;

	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 LIBUSB_ERROR_IO;
	}

	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;
		}

		r = enumerate_device(ctx, &discdevs, busnum, (uint8_t) devaddr, NULL);
		if (r < 0)
			goto out;
	}

	*_discdevs = discdevs;
out:
	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 *usbfs_fallback)
{
	int r;
	FILE *fd;
	char filename[PATH_MAX];
	int busnum;
	int devaddr;

	usbi_dbg("scan %s", devname);

	/* determine descriptors presence ahead of time, we need to know this
	 * when we reach initialize_device */
	if (sysfs_has_descriptors == -1) {
		struct stat statbuf;

		snprintf(filename, PATH_MAX, "%s/%s/descriptors", SYSFS_DEVICE_PATH,
			devname);
		r = stat(filename, &statbuf);
		if (r == 0 && S_ISREG(statbuf.st_mode)) {
			usbi_dbg("sysfs descriptors available");
			sysfs_has_descriptors = 1;
		} else {
			usbi_dbg("sysfs descriptors not available");
			sysfs_has_descriptors = 0;
		}
	}

	snprintf(filename, PATH_MAX, "%s/%s/busnum", SYSFS_DEVICE_PATH, devname);
	fd = fopen(filename, "r");
	if (!fd) {
		if (errno == ENOENT) {
			usbi_dbg("busnum not found, cannot relate sysfs to usbfs, "
				"falling back on pure usbfs");
			sysfs_can_relate_devices = 0;
			*usbfs_fallback = 1;
			return LIBUSB_ERROR_OTHER;
		}
		usbi_err(ctx, "open busnum failed, errno=%d", errno);
		return LIBUSB_ERROR_IO;
	}

	sysfs_can_relate_devices = 1;

	r = fscanf(fd, "%d", &busnum);
	fclose(fd);
	if (r != 1) {
		usbi_err(ctx, "fscanf busnum returned %d, errno=%d", r, errno);
		return LIBUSB_ERROR_IO;
	}

	snprintf(filename, PATH_MAX, "%s/%s/devnum", SYSFS_DEVICE_PATH, devname);
	fd = fopen(filename, "r");
	if (!fd) {
		usbi_err(ctx, "open devnum failed, errno=%d", errno);
		return LIBUSB_ERROR_IO;
	}

	r = fscanf(fd, "%d", &devaddr);
	fclose(fd);
	if (r != 1) {
		usbi_err(ctx, "fscanf devnum returned %d, errno=%d", r, errno);
		return LIBUSB_ERROR_IO;
	}

	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, int *usbfs_fallback)
{
	struct discovered_devs *discdevs = *_discdevs;
	DIR *devices = opendir(SYSFS_DEVICE_PATH);
	struct dirent *entry;
	int r = 0;

	if (!devices) {
		usbi_err(ctx, "opendir devices failed errno=%d", errno);
		return LIBUSB_ERROR_IO;
	}

	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;

		r = sysfs_scan_device(ctx, &discdevs_new, entry->d_name,
			usbfs_fallback);
		if (r < 0)
			goto out;
		discdevs = discdevs_new;
	}	

out:
	closedir(devices);
	*_discdevs = discdevs;
	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, sometimes we have
	 * sysfs but not enough information to relate sysfs devices to usbfs
	 * nodes. the usbfs_fallback variable is used to indicate that we should
	 * fall back on usbfs.
	 */
	if (sysfs_can_relate_devices != 0) {
		int usbfs_fallback = 0;
		int r = sysfs_get_device_list(ctx, _discdevs, &usbfs_fallback);
		if (!usbfs_fallback)
			return r;
	}

	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);
	hpriv->fd = open(filename, O_RDWR);
	if (hpriv->fd < 0) {
		if (errno == EACCES) {
			fprintf(stderr, "libusb couldn't open USB device %s: "
				"Permission denied.\n"
				"libusb requires write access to USB device nodes.\n",
				filename);
			return LIBUSB_ERROR_ACCESS;
		} else if (errno == ENOENT) {
			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);