libusb/os/netbsd_usb.c

   1 /*
   2  * Copyright © 2011 Martin Pieuchot <mpi@openbsd.org>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #include <config.h>
  20
  21 #include <sys/time.h>
  22 #include <sys/types.h>
  23
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <dev/usb/usb.h>
  32
  33 #include "libusbi.h"
  34
  35 struct device_priv {
  36         char devnode[16];
  37         int fd;
  38
  39         unsigned char *cdesc;                   /* active config descriptor */
  40         usb_device_descriptor_t ddesc;          /* usb device descriptor */
  41 };
  42
  43 struct handle_priv {
  44         int endpoints[USB_MAX_ENDPOINTS];
  45 };
  46
  47 /*
  48  * Backend functions
  49  */
  50 static int netbsd_get_device_list(struct libusb_context *,
  51     struct discovered_devs **);
  52 static int netbsd_open(struct libusb_device_handle *);
  53 static void netbsd_close(struct libusb_device_handle *);
  54
  55 static int netbsd_get_device_descriptor(struct libusb_device *, unsigned char *,
  56     int *);
  57 static int netbsd_get_active_config_descriptor(struct libusb_device *,
  58     unsigned char *, size_t, int *);
  59 static int netbsd_get_config_descriptor(struct libusb_device *, uint8_t,
  60     unsigned char *, size_t, int *);
  61
  62 static int netbsd_get_configuration(struct libusb_device_handle *, int *);
  63 static int netbsd_set_configuration(struct libusb_device_handle *, int);
  64
  65 static int netbsd_claim_interface(struct libusb_device_handle *, int);
  66 static int netbsd_release_interface(struct libusb_device_handle *, int);
  67
  68 static int netbsd_set_interface_altsetting(struct libusb_device_handle *, int,
  69     int);
  70 static int netbsd_clear_halt(struct libusb_device_handle *, unsigned char);
  71 static int netbsd_reset_device(struct libusb_device_handle *);
  72 static void netbsd_destroy_device(struct libusb_device *);
  73
  74 static int netbsd_submit_transfer(struct usbi_transfer *);
  75 static int netbsd_cancel_transfer(struct usbi_transfer *);
  76 static void netbsd_clear_transfer_priv(struct usbi_transfer *);
  77 static int netbsd_handle_transfer_completion(struct usbi_transfer *);
  78 static int netbsd_clock_gettime(int, struct timespec *);
  79
  80 /*
  81  * Private functions
  82  */
  83 static int _errno_to_libusb(int);
  84 static int _cache_active_config_descriptor(struct libusb_device *, int);
  85 static int _sync_control_transfer(struct usbi_transfer *);
  86 static int _sync_gen_transfer(struct usbi_transfer *);
  87 static int _access_endpoint(struct libusb_transfer *);
  88
  89 const struct usbi_os_backend usbi_backend = {
  90         "Synchronous NetBSD backend",
  91         0,
  92         NULL,                           /* init() */
  93         NULL,                           /* exit() */
  94         netbsd_get_device_list,
  95         NULL,                           /* hotplug_poll */
  96         netbsd_open,
  97         netbsd_close,
  98
  99         netbsd_get_device_descriptor,
 100         netbsd_get_active_config_descriptor,
 101         netbsd_get_config_descriptor,
 102         NULL,                           /* get_config_descriptor_by_value() */
 103
 104         netbsd_get_configuration,
 105         netbsd_set_configuration,
 106
 107         netbsd_claim_interface,
 108         netbsd_release_interface,
 109
 110         netbsd_set_interface_altsetting,
 111         netbsd_clear_halt,
 112         netbsd_reset_device,
 113
 114         NULL,                           /* alloc_streams */
 115         NULL,                           /* free_streams */
 116
 117         NULL,                           /* dev_mem_alloc() */
 118         NULL,                           /* dev_mem_free() */
 119
 120         NULL,                           /* kernel_driver_active() */
 121         NULL,                           /* detach_kernel_driver() */
 122         NULL,                           /* attach_kernel_driver() */
 123
 124         netbsd_destroy_device,
 125
 126         netbsd_submit_transfer,
 127         netbsd_cancel_transfer,
 128         netbsd_clear_transfer_priv,
 129
 130         NULL,                           /* handle_events() */
 131         netbsd_handle_transfer_completion,
 132
 133         netbsd_clock_gettime,
 134         0,                              /* context_priv_size */
 135         sizeof(struct device_priv),
 136         sizeof(struct handle_priv),
 137         0,                              /* transfer_priv_size */
 138 };
 139
 140 int
 141 netbsd_get_device_list(struct libusb_context * ctx,
 142         struct discovered_devs **discdevs)
 143 {
 144         struct libusb_device *dev;
 145         struct device_priv *dpriv;
 146         struct usb_device_info di;
 147         unsigned long session_id;
 148         char devnode[16];
 149         int fd, err, i;
 150
 151         usbi_dbg("");
 152
 153         /* Only ugen(4) is supported */
 154         for (i = 0; i < USB_MAX_DEVICES; i++) {
 155                 /* Control endpoint is always .00 */
 156                 snprintf(devnode, sizeof(devnode), "/dev/ugen%d.00", i);
 157
 158                 if ((fd = open(devnode, O_RDONLY)) < 0) {
 159                         if (errno != ENOENT && errno != ENXIO)
 160                                 usbi_err(ctx, "could not open %s", devnode);
 161                         continue;
 162                 }
 163
 164                 if (ioctl(fd, USB_GET_DEVICEINFO, &di) < 0)
 165                         continue;
 166
 167                 session_id = (di.udi_bus << 8 | di.udi_addr);
 168                 dev = usbi_get_device_by_session_id(ctx, session_id);
 169
 170                 if (dev == NULL) {
 171                         dev = usbi_alloc_device(ctx, session_id);
 172                         if (dev == NULL)
 173                                 return (LIBUSB_ERROR_NO_MEM);
 174
 175                         dev->bus_number = di.udi_bus;
 176                         dev->device_address = di.udi_addr;
 177                         dev->speed = di.udi_speed;
 178
 179                         dpriv = (struct device_priv *)dev->os_priv;
 180                         strlcpy(dpriv->devnode, devnode, sizeof(devnode));
 181                         dpriv->fd = -1;
 182
 183                         if (ioctl(fd, USB_GET_DEVICE_DESC, &dpriv->ddesc) < 0) {
 184                                 err = errno;
 185                                 goto error;
 186                         }
 187
 188                         dpriv->cdesc = NULL;
 189                         if (_cache_active_config_descriptor(dev, fd)) {
 190                                 err = errno;
 191                                 goto error;
 192                         }
 193
 194                         if ((err = usbi_sanitize_device(dev)))
 195                                 goto error;
 196                 }
 197                 close(fd);
 198
 199                 if (discovered_devs_append(*discdevs, dev) == NULL)
 200                         return (LIBUSB_ERROR_NO_MEM);
 201
 202                 libusb_unref_device(dev);
 203         }
 204
 205         return (LIBUSB_SUCCESS);
 206
 207 error:
 208         close(fd);
 209         libusb_unref_device(dev);
 210         return _errno_to_libusb(err);
 211 }
 212
 213 int
 214 netbsd_open(struct libusb_device_handle *handle)
 215 {
 216         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 217         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 218
 219         dpriv->fd = open(dpriv->devnode, O_RDWR);
 220         if (dpriv->fd < 0) {
 221                 dpriv->fd = open(dpriv->devnode, O_RDONLY);
 222                 if (dpriv->fd < 0)
 223                         return _errno_to_libusb(errno);
 224         }
 225
 226         usbi_dbg("open %s: fd %d", dpriv->devnode, dpriv->fd);
 227
 228         return (LIBUSB_SUCCESS);
 229 }
 230
 231 void
 232 netbsd_close(struct libusb_device_handle *handle)
 233 {
 234         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 235         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 236
 237         usbi_dbg("close: fd %d", dpriv->fd);
 238
 239         close(dpriv->fd);
 240         dpriv->fd = -1;
 241 }
 242
 243 int
 244 netbsd_get_device_descriptor(struct libusb_device *dev, unsigned char *buf,
 245     int *host_endian)
 246 {
 247         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 248
 249         usbi_dbg("");
 250
 251         memcpy(buf, &dpriv->ddesc, DEVICE_DESC_LENGTH);
 252
 253         *host_endian = 0;
 254
 255         return (LIBUSB_SUCCESS);
 256 }
 257
 258 int
 259 netbsd_get_active_config_descriptor(struct libusb_device *dev,
 260     unsigned char *buf, size_t len, int *host_endian)
 261 {
 262         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 263         usb_config_descriptor_t *ucd;
 264
 265         ucd = (usb_config_descriptor_t *) dpriv->cdesc;
 266         len = MIN(len, UGETW(ucd->wTotalLength));
 267
 268         usbi_dbg("len %d", len);
 269
 270         memcpy(buf, dpriv->cdesc, len);
 271
 272         *host_endian = 0;
 273
 274         return len;
 275 }
 276
 277 int
 278 netbsd_get_config_descriptor(struct libusb_device *dev, uint8_t idx,
 279     unsigned char *buf, size_t len, int *host_endian)
 280 {
 281         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 282         struct usb_full_desc ufd;
 283         int fd, err;
 284
 285         usbi_dbg("index %d, len %d", idx, len);
 286
 287         /* A config descriptor may be requested before opening the device */
 288         if (dpriv->fd >= 0) {
 289                 fd = dpriv->fd;
 290         } else {
 291                 fd = open(dpriv->devnode, O_RDONLY);
 292                 if (fd < 0)
 293                         return _errno_to_libusb(errno);
 294         }
 295
 296         ufd.ufd_config_index = idx;
 297         ufd.ufd_size = len;
 298         ufd.ufd_data = buf;
 299
 300         if ((ioctl(fd, USB_GET_FULL_DESC, &ufd)) < 0) {
 301                 err = errno;
 302                 if (dpriv->fd < 0)
 303                         close(fd);
 304                 return _errno_to_libusb(err);
 305         }
 306
 307         if (dpriv->fd < 0)
 308                 close(fd);
 309
 310         *host_endian = 0;
 311
 312         return len;
 313 }
 314
 315 int
 316 netbsd_get_configuration(struct libusb_device_handle *handle, int *config)
 317 {
 318         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 319
 320         usbi_dbg("");
 321
 322         if (ioctl(dpriv->fd, USB_GET_CONFIG, config) < 0)
 323                 return _errno_to_libusb(errno);
 324
 325         usbi_dbg("configuration %d", *config);
 326
 327         return (LIBUSB_SUCCESS);
 328 }
 329
 330 int
 331 netbsd_set_configuration(struct libusb_device_handle *handle, int config)
 332 {
 333         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 334
 335         usbi_dbg("configuration %d", config);
 336
 337         if (ioctl(dpriv->fd, USB_SET_CONFIG, &config) < 0)
 338                 return _errno_to_libusb(errno);
 339
 340         return _cache_active_config_descriptor(handle->dev, dpriv->fd);
 341 }
 342
 343 int
 344 netbsd_claim_interface(struct libusb_device_handle *handle, int iface)
 345 {
 346         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 347         int i;
 348
 349         for (i = 0; i < USB_MAX_ENDPOINTS; i++)
 350                 hpriv->endpoints[i] = -1;
 351
 352         return (LIBUSB_SUCCESS);
 353 }
 354
 355 int
 356 netbsd_release_interface(struct libusb_device_handle *handle, int iface)
 357 {
 358         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 359         int i;
 360
 361         for (i = 0; i < USB_MAX_ENDPOINTS; i++)
 362                 if (hpriv->endpoints[i] >= 0)
 363                         close(hpriv->endpoints[i]);
 364
 365         return (LIBUSB_SUCCESS);
 366 }
 367
 368 int
 369 netbsd_set_interface_altsetting(struct libusb_device_handle *handle, int iface,
 370     int altsetting)
 371 {
 372         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 373         struct usb_alt_interface intf;
 374
 375         usbi_dbg("iface %d, setting %d", iface, altsetting);
 376
 377         memset(&intf, 0, sizeof(intf));
 378
 379         intf.uai_interface_index = iface;
 380         intf.uai_alt_no = altsetting;
 381
 382         if (ioctl(dpriv->fd, USB_SET_ALTINTERFACE, &intf) < 0)
 383                 return _errno_to_libusb(errno);
 384
 385         return (LIBUSB_SUCCESS);
 386 }
 387
 388 int
 389 netbsd_clear_halt(struct libusb_device_handle *handle, unsigned char endpoint)
 390 {
 391         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 392         struct usb_ctl_request req;
 393
 394         usbi_dbg("");
 395
 396         req.ucr_request.bmRequestType = UT_WRITE_ENDPOINT;
 397         req.ucr_request.bRequest = UR_CLEAR_FEATURE;
 398         USETW(req.ucr_request.wValue, UF_ENDPOINT_HALT);
 399         USETW(req.ucr_request.wIndex, endpoint);
 400         USETW(req.ucr_request.wLength, 0);
 401
 402         if (ioctl(dpriv->fd, USB_DO_REQUEST, &req) < 0)
 403                 return _errno_to_libusb(errno);
 404
 405         return (LIBUSB_SUCCESS);
 406 }
 407
 408 int
 409 netbsd_reset_device(struct libusb_device_handle *handle)
 410 {
 411         usbi_dbg("");
 412
 413         return (LIBUSB_ERROR_NOT_SUPPORTED);
 414 }
 415
 416 void
 417 netbsd_destroy_device(struct libusb_device *dev)
 418 {
 419         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 420
 421         usbi_dbg("");
 422
 423         free(dpriv->cdesc);
 424 }
 425
 426 int
 427 netbsd_submit_transfer(struct usbi_transfer *itransfer)
 428 {
 429         struct libusb_transfer *transfer;
 430         struct handle_priv *hpriv;
 431         int err = 0;
 432
 433         usbi_dbg("");
 434
 435         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 436         hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;
 437
 438         switch (transfer->type) {
 439         case LIBUSB_TRANSFER_TYPE_CONTROL:
 440                 err = _sync_control_transfer(itransfer);
 441                 break;
 442         case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
 443                 if (IS_XFEROUT(transfer)) {
 444                         /* Isochronous write is not supported */
 445                         err = LIBUSB_ERROR_NOT_SUPPORTED;
 446                         break;
 447                 }
 448                 err = _sync_gen_transfer(itransfer);
 449                 break;
 450         case LIBUSB_TRANSFER_TYPE_BULK:
 451         case LIBUSB_TRANSFER_TYPE_INTERRUPT:
 452                 if (IS_XFEROUT(transfer) &&
 453                     transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET) {
 454                         err = LIBUSB_ERROR_NOT_SUPPORTED;
 455                         break;
 456                 }
 457                 err = _sync_gen_transfer(itransfer);
 458                 break;
 459         case LIBUSB_TRANSFER_TYPE_BULK_STREAM:
 460                 err = LIBUSB_ERROR_NOT_SUPPORTED;
 461                 break;
 462         }
 463
 464         if (err)
 465                 return (err);
 466
 467         usbi_signal_transfer_completion(itransfer);
 468
 469         return (LIBUSB_SUCCESS);
 470 }
 471
 472 int
 473 netbsd_cancel_transfer(struct usbi_transfer *itransfer)
 474 {
 475         usbi_dbg("");
 476
 477         return (LIBUSB_ERROR_NOT_SUPPORTED);
 478 }
 479
 480 void
 481 netbsd_clear_transfer_priv(struct usbi_transfer *itransfer)
 482 {
 483         usbi_dbg("");
 484
 485         /* Nothing to do */
 486 }
 487
 488 int
 489 netbsd_handle_transfer_completion(struct usbi_transfer *itransfer)
 490 {
 491         return usbi_handle_transfer_completion(itransfer, LIBUSB_TRANSFER_COMPLETED);
 492 }
 493
 494 int
 495 netbsd_clock_gettime(int clkid, struct timespec *tp)
 496 {
 497         usbi_dbg("clock %d", clkid);
 498
 499         if (clkid == USBI_CLOCK_REALTIME)
 500                 return clock_gettime(CLOCK_REALTIME, tp);
 501
 502         if (clkid == USBI_CLOCK_MONOTONIC)
 503                 return clock_gettime(CLOCK_MONOTONIC, tp);
 504
 505         return (LIBUSB_ERROR_INVALID_PARAM);
 506 }
 507
 508 int
 509 _errno_to_libusb(int err)
 510 {
 511         switch (err) {
 512         case EIO:
 513                 return (LIBUSB_ERROR_IO);
 514         case EACCES:
 515                 return (LIBUSB_ERROR_ACCESS);
 516         case ENOENT:
 517                 return (LIBUSB_ERROR_NO_DEVICE);
 518         case ENOMEM:
 519                 return (LIBUSB_ERROR_NO_MEM);
 520         }
 521
 522         usbi_dbg("error: %s", strerror(err));
 523
 524         return (LIBUSB_ERROR_OTHER);
 525 }
 526
 527 int
 528 _cache_active_config_descriptor(struct libusb_device *dev, int fd)
 529 {
 530         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 531         struct usb_config_desc ucd;
 532         struct usb_full_desc ufd;
 533         unsigned char* buf;
 534         int len;
 535
 536         usbi_dbg("fd %d", fd);
 537
 538         ucd.ucd_config_index = USB_CURRENT_CONFIG_INDEX;
 539
 540         if ((ioctl(fd, USB_GET_CONFIG_DESC, &ucd)) < 0)
 541                 return _errno_to_libusb(errno);
 542
 543         usbi_dbg("active bLength %d", ucd.ucd_desc.bLength);
 544
 545         len = UGETW(ucd.ucd_desc.wTotalLength);
 546         buf = malloc(len);
 547         if (buf == NULL)
 548                 return (LIBUSB_ERROR_NO_MEM);
 549
 550         ufd.ufd_config_index = ucd.ucd_config_index;
 551         ufd.ufd_size = len;
 552         ufd.ufd_data = buf;
 553
 554         usbi_dbg("index %d, len %d", ufd.ufd_config_index, len);
 555
 556         if ((ioctl(fd, USB_GET_FULL_DESC, &ufd)) < 0) {
 557                 free(buf);
 558                 return _errno_to_libusb(errno);
 559         }
 560
 561         if (dpriv->cdesc)
 562                 free(dpriv->cdesc);
 563         dpriv->cdesc = buf;
 564
 565         return (0);
 566 }
 567
 568 int
 569 _sync_control_transfer(struct usbi_transfer *itransfer)
 570 {
 571         struct libusb_transfer *transfer;
 572         struct libusb_control_setup *setup;
 573         struct device_priv *dpriv;
 574         struct usb_ctl_request req;
 575
 576         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 577         dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;
 578         setup = (struct libusb_control_setup *)transfer->buffer;
 579
 580         usbi_dbg("type %d request %d value %d index %d length %d timeout %d",
 581             setup->bmRequestType, setup->bRequest,
 582             libusb_le16_to_cpu(setup->wValue),
 583             libusb_le16_to_cpu(setup->wIndex),
 584             libusb_le16_to_cpu(setup->wLength), transfer->timeout);
 585
 586         req.ucr_request.bmRequestType = setup->bmRequestType;
 587         req.ucr_request.bRequest = setup->bRequest;
 588         /* Don't use USETW, libusb already deals with the endianness */
 589         (*(uint16_t *)req.ucr_request.wValue) = setup->wValue;
 590         (*(uint16_t *)req.ucr_request.wIndex) = setup->wIndex;
 591         (*(uint16_t *)req.ucr_request.wLength) = setup->wLength;
 592         req.ucr_data = transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE;
 593
 594         if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
 595                 req.ucr_flags = USBD_SHORT_XFER_OK;
 596
 597         if ((ioctl(dpriv->fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
 598                 return _errno_to_libusb(errno);
 599
 600         if ((ioctl(dpriv->fd, USB_DO_REQUEST, &req)) < 0)
 601                 return _errno_to_libusb(errno);
 602
 603         itransfer->transferred = req.ucr_actlen;
 604
 605         usbi_dbg("transferred %d", itransfer->transferred);
 606
 607         return (0);
 608 }
 609
 610 int
 611 _access_endpoint(struct libusb_transfer *transfer)
 612 {
 613         struct handle_priv *hpriv;
 614         struct device_priv *dpriv;
 615         char *s, devnode[16];
 616         int fd, endpt;
 617         mode_t mode;
 618
 619         hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;
 620         dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;
 621
 622         endpt = UE_GET_ADDR(transfer->endpoint);
 623         mode = IS_XFERIN(transfer) ? O_RDONLY : O_WRONLY;
 624
 625         usbi_dbg("endpoint %d mode %d", endpt, mode);
 626
 627         if (hpriv->endpoints[endpt] < 0) {
 628                 /* Pick the right node given the control one */
 629                 strlcpy(devnode, dpriv->devnode, sizeof(devnode));
 630                 s = strchr(devnode, '.');
 631                 snprintf(s, 4, ".%02d", endpt);
 632
 633                 /* We may need to read/write to the same endpoint later. */
 634                 if (((fd = open(devnode, O_RDWR)) < 0) && (errno == ENXIO))
 635                         if ((fd = open(devnode, mode)) < 0)
 636                                 return (-1);
 637
 638                 hpriv->endpoints[endpt] = fd;
 639         }
 640
 641         return (hpriv->endpoints[endpt]);
 642 }
 643
 644 int
 645 _sync_gen_transfer(struct usbi_transfer *itransfer)
 646 {
 647         struct libusb_transfer *transfer;
 648         int fd, nr = 1;
 649
 650         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 651
 652         /*
 653          * Bulk, Interrupt or Isochronous transfer depends on the
 654          * endpoint and thus the node to open.
 655          */
 656         if ((fd = _access_endpoint(transfer)) < 0)
 657                 return _errno_to_libusb(errno);
 658
 659         if ((ioctl(fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
 660                 return _errno_to_libusb(errno);
 661
 662         if (IS_XFERIN(transfer)) {
 663                 if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
 664                         if ((ioctl(fd, USB_SET_SHORT_XFER, &nr)) < 0)
 665                                 return _errno_to_libusb(errno);
 666
 667                 nr = read(fd, transfer->buffer, transfer->length);
 668         } else {
 669                 nr = write(fd, transfer->buffer, transfer->length);
 670         }
 671
 672         if (nr < 0)
 673                 return _errno_to_libusb(errno);
 674
 675         itransfer->transferred = nr;
 676
 677         return (0);
 678 }