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 netbsd_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,                           /* kernel_driver_active() */
 118         NULL,                           /* detach_kernel_driver() */
 119         NULL,                           /* attach_kernel_driver() */
 120
 121         netbsd_destroy_device,
 122
 123         netbsd_submit_transfer,
 124         netbsd_cancel_transfer,
 125         netbsd_clear_transfer_priv,
 126
 127         NULL,                           /* handle_events() */
 128         netbsd_handle_transfer_completion,
 129
 130         netbsd_clock_gettime,
 131         sizeof(struct device_priv),
 132         sizeof(struct handle_priv),
 133         0,                              /* transfer_priv_size */
 134         0,                              /* add_iso_packet_size */
 135 };
 136
 137 int
 138 netbsd_get_device_list(struct libusb_context * ctx,
 139         struct discovered_devs **discdevs)
 140 {
 141         struct libusb_device *dev;
 142         struct device_priv *dpriv;
 143         struct usb_device_info di;
 144         unsigned long session_id;
 145         char devnode[16];
 146         int fd, err, i;
 147
 148         usbi_dbg("");
 149
 150         /* Only ugen(4) is supported */
 151         for (i = 0; i < USB_MAX_DEVICES; i++) {
 152                 /* Control endpoint is always .00 */
 153                 snprintf(devnode, sizeof(devnode), "/dev/ugen%d.00", i);
 154
 155                 if ((fd = open(devnode, O_RDONLY)) < 0) {
 156                         if (errno != ENOENT && errno != ENXIO)
 157                                 usbi_err(ctx, "could not open %s", devnode);
 158                         continue;
 159                 }
 160
 161                 if (ioctl(fd, USB_GET_DEVICEINFO, &di) < 0)
 162                         continue;
 163
 164                 session_id = (di.udi_bus << 8 | di.udi_addr);
 165                 dev = usbi_get_device_by_session_id(ctx, session_id);
 166
 167                 if (dev == NULL) {
 168                         dev = usbi_alloc_device(ctx, session_id);
 169                         if (dev == NULL)
 170                                 return (LIBUSB_ERROR_NO_MEM);
 171
 172                         dev->bus_number = di.udi_bus;
 173                         dev->device_address = di.udi_addr;
 174                         dev->speed = di.udi_speed;
 175
 176                         dpriv = (struct device_priv *)dev->os_priv;
 177                         strlcpy(dpriv->devnode, devnode, sizeof(devnode));
 178                         dpriv->fd = -1;
 179
 180                         if (ioctl(fd, USB_GET_DEVICE_DESC, &dpriv->ddesc) < 0) {
 181                                 err = errno;
 182                                 goto error;
 183                         }
 184
 185                         dpriv->cdesc = NULL;
 186                         if (_cache_active_config_descriptor(dev, fd)) {
 187                                 err = errno;
 188                                 goto error;
 189                         }
 190
 191                         if ((err = usbi_sanitize_device(dev)))
 192                                 goto error;
 193                 }
 194                 close(fd);
 195
 196                 if (discovered_devs_append(*discdevs, dev) == NULL)
 197                         return (LIBUSB_ERROR_NO_MEM);
 198
 199                 libusb_unref_device(dev);
 200         }
 201
 202         return (LIBUSB_SUCCESS);
 203
 204 error:
 205         close(fd);
 206         libusb_unref_device(dev);
 207         return _errno_to_libusb(err);
 208 }
 209
 210 int
 211 netbsd_open(struct libusb_device_handle *handle)
 212 {
 213         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 214         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 215
 216         dpriv->fd = open(dpriv->devnode, O_RDWR);
 217         if (dpriv->fd < 0) {
 218                 dpriv->fd = open(dpriv->devnode, O_RDONLY);
 219                 if (dpriv->fd < 0)
 220                         return _errno_to_libusb(errno);
 221         }
 222
 223         usbi_dbg("open %s: fd %d", dpriv->devnode, dpriv->fd);
 224
 225         return (LIBUSB_SUCCESS);
 226 }
 227
 228 void
 229 netbsd_close(struct libusb_device_handle *handle)
 230 {
 231         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 232         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 233
 234         usbi_dbg("close: fd %d", dpriv->fd);
 235
 236         close(dpriv->fd);
 237         dpriv->fd = -1;
 238 }
 239
 240 int
 241 netbsd_get_device_descriptor(struct libusb_device *dev, unsigned char *buf,
 242     int *host_endian)
 243 {
 244         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 245
 246         usbi_dbg("");
 247
 248         memcpy(buf, &dpriv->ddesc, DEVICE_DESC_LENGTH);
 249
 250         *host_endian = 0;
 251
 252         return (LIBUSB_SUCCESS);
 253 }
 254
 255 int
 256 netbsd_get_active_config_descriptor(struct libusb_device *dev,
 257     unsigned char *buf, size_t len, int *host_endian)
 258 {
 259         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 260         usb_config_descriptor_t *ucd;
 261
 262         ucd = (usb_config_descriptor_t *) dpriv->cdesc;
 263         len = MIN(len, UGETW(ucd->wTotalLength));
 264
 265         usbi_dbg("len %d", len);
 266
 267         memcpy(buf, dpriv->cdesc, len);
 268
 269         *host_endian = 0;
 270
 271         return len;
 272 }
 273
 274 int
 275 netbsd_get_config_descriptor(struct libusb_device *dev, uint8_t idx,
 276     unsigned char *buf, size_t len, int *host_endian)
 277 {
 278         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 279         struct usb_full_desc ufd;
 280         int fd, err;
 281
 282         usbi_dbg("index %d, len %d", idx, len);
 283
 284         /* A config descriptor may be requested before opening the device */
 285         if (dpriv->fd >= 0) {
 286                 fd = dpriv->fd;
 287         } else {
 288                 fd = open(dpriv->devnode, O_RDONLY);
 289                 if (fd < 0)
 290                         return _errno_to_libusb(errno);
 291         }
 292
 293         ufd.ufd_config_index = idx;
 294         ufd.ufd_size = len;
 295         ufd.ufd_data = buf;
 296
 297         if ((ioctl(fd, USB_GET_FULL_DESC, &ufd)) < 0) {
 298                 err = errno;
 299                 if (dpriv->fd < 0)
 300                         close(fd);
 301                 return _errno_to_libusb(err);
 302         }
 303
 304         if (dpriv->fd < 0)
 305                 close(fd);
 306
 307         *host_endian = 0;
 308
 309         return len;
 310 }
 311
 312 int
 313 netbsd_get_configuration(struct libusb_device_handle *handle, int *config)
 314 {
 315         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 316
 317         usbi_dbg("");
 318
 319         if (ioctl(dpriv->fd, USB_GET_CONFIG, config) < 0)
 320                 return _errno_to_libusb(errno);
 321
 322         usbi_dbg("configuration %d", *config);
 323
 324         return (LIBUSB_SUCCESS);
 325 }
 326
 327 int
 328 netbsd_set_configuration(struct libusb_device_handle *handle, int config)
 329 {
 330         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 331
 332         usbi_dbg("configuration %d", config);
 333
 334         if (ioctl(dpriv->fd, USB_SET_CONFIG, &config) < 0)
 335                 return _errno_to_libusb(errno);
 336
 337         return _cache_active_config_descriptor(handle->dev, dpriv->fd);
 338 }
 339
 340 int
 341 netbsd_claim_interface(struct libusb_device_handle *handle, int iface)
 342 {
 343         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 344         int i;
 345
 346         for (i = 0; i < USB_MAX_ENDPOINTS; i++)
 347                 hpriv->endpoints[i] = -1;
 348
 349         return (LIBUSB_SUCCESS);
 350 }
 351
 352 int
 353 netbsd_release_interface(struct libusb_device_handle *handle, int iface)
 354 {
 355         struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
 356         int i;
 357
 358         for (i = 0; i < USB_MAX_ENDPOINTS; i++)
 359                 if (hpriv->endpoints[i] >= 0)
 360                         close(hpriv->endpoints[i]);
 361
 362         return (LIBUSB_SUCCESS);
 363 }
 364
 365 int
 366 netbsd_set_interface_altsetting(struct libusb_device_handle *handle, int iface,
 367     int altsetting)
 368 {
 369         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 370         struct usb_alt_interface intf;
 371
 372         usbi_dbg("iface %d, setting %d", iface, altsetting);
 373
 374         memset(&intf, 0, sizeof(intf));
 375
 376         intf.uai_interface_index = iface;
 377         intf.uai_alt_no = altsetting;
 378
 379         if (ioctl(dpriv->fd, USB_SET_ALTINTERFACE, &intf) < 0)
 380                 return _errno_to_libusb(errno);
 381
 382         return (LIBUSB_SUCCESS);
 383 }
 384
 385 int
 386 netbsd_clear_halt(struct libusb_device_handle *handle, unsigned char endpoint)
 387 {
 388         struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
 389         struct usb_ctl_request req;
 390
 391         usbi_dbg("");
 392
 393         req.ucr_request.bmRequestType = UT_WRITE_ENDPOINT;
 394         req.ucr_request.bRequest = UR_CLEAR_FEATURE;
 395         USETW(req.ucr_request.wValue, UF_ENDPOINT_HALT);
 396         USETW(req.ucr_request.wIndex, endpoint);
 397         USETW(req.ucr_request.wLength, 0);
 398
 399         if (ioctl(dpriv->fd, USB_DO_REQUEST, &req) < 0)
 400                 return _errno_to_libusb(errno);
 401
 402         return (LIBUSB_SUCCESS);
 403 }
 404
 405 int
 406 netbsd_reset_device(struct libusb_device_handle *handle)
 407 {
 408         usbi_dbg("");
 409
 410         return (LIBUSB_ERROR_NOT_SUPPORTED);
 411 }
 412
 413 void
 414 netbsd_destroy_device(struct libusb_device *dev)
 415 {
 416         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 417
 418         usbi_dbg("");
 419
 420         free(dpriv->cdesc);
 421 }
 422
 423 int
 424 netbsd_submit_transfer(struct usbi_transfer *itransfer)
 425 {
 426         struct libusb_transfer *transfer;
 427         struct handle_priv *hpriv;
 428         int err = 0;
 429
 430         usbi_dbg("");
 431
 432         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 433         hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;
 434
 435         switch (transfer->type) {
 436         case LIBUSB_TRANSFER_TYPE_CONTROL:
 437                 err = _sync_control_transfer(itransfer);
 438                 break;
 439         case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
 440                 if (IS_XFEROUT(transfer)) {
 441                         /* Isochronous write is not supported */
 442                         err = LIBUSB_ERROR_NOT_SUPPORTED;
 443                         break;
 444                 }
 445                 err = _sync_gen_transfer(itransfer);
 446                 break;
 447         case LIBUSB_TRANSFER_TYPE_BULK:
 448         case LIBUSB_TRANSFER_TYPE_INTERRUPT:
 449                 if (IS_XFEROUT(transfer) &&
 450                     transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET) {
 451                         err = LIBUSB_ERROR_NOT_SUPPORTED;
 452                         break;
 453                 }
 454                 err = _sync_gen_transfer(itransfer);
 455                 break;
 456         case LIBUSB_TRANSFER_TYPE_BULK_STREAM:
 457                 err = LIBUSB_ERROR_NOT_SUPPORTED;
 458                 break;
 459         }
 460
 461         if (err)
 462                 return (err);
 463
 464         usbi_signal_transfer_completion(itransfer);
 465
 466         return (LIBUSB_SUCCESS);
 467 }
 468
 469 int
 470 netbsd_cancel_transfer(struct usbi_transfer *itransfer)
 471 {
 472         usbi_dbg("");
 473
 474         return (LIBUSB_ERROR_NOT_SUPPORTED);
 475 }
 476
 477 void
 478 netbsd_clear_transfer_priv(struct usbi_transfer *itransfer)
 479 {
 480         usbi_dbg("");
 481
 482         /* Nothing to do */
 483 }
 484
 485 int
 486 netbsd_handle_transfer_completion(struct usbi_transfer *itransfer)
 487 {
 488         return usbi_handle_transfer_completion(itransfer, LIBUSB_TRANSFER_COMPLETED);
 489 }
 490
 491 int
 492 netbsd_clock_gettime(int clkid, struct timespec *tp)
 493 {
 494         usbi_dbg("clock %d", clkid);
 495
 496         if (clkid == USBI_CLOCK_REALTIME)
 497                 return clock_gettime(CLOCK_REALTIME, tp);
 498
 499         if (clkid == USBI_CLOCK_MONOTONIC)
 500                 return clock_gettime(CLOCK_MONOTONIC, tp);
 501
 502         return (LIBUSB_ERROR_INVALID_PARAM);
 503 }
 504
 505 int
 506 _errno_to_libusb(int err)
 507 {
 508         switch (err) {
 509         case EIO:
 510                 return (LIBUSB_ERROR_IO);
 511         case EACCES:
 512                 return (LIBUSB_ERROR_ACCESS);
 513         case ENOENT:
 514                 return (LIBUSB_ERROR_NO_DEVICE);
 515         case ENOMEM:
 516                 return (LIBUSB_ERROR_NO_MEM);
 517         }
 518
 519         usbi_dbg("error: %s", strerror(err));
 520
 521         return (LIBUSB_ERROR_OTHER);
 522 }
 523
 524 int
 525 _cache_active_config_descriptor(struct libusb_device *dev, int fd)
 526 {
 527         struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
 528         struct usb_config_desc ucd;
 529         struct usb_full_desc ufd;
 530         unsigned char* buf;
 531         int len;
 532
 533         usbi_dbg("fd %d", fd);
 534
 535         ucd.ucd_config_index = USB_CURRENT_CONFIG_INDEX;
 536
 537         if ((ioctl(fd, USB_GET_CONFIG_DESC, &ucd)) < 0)
 538                 return _errno_to_libusb(errno);
 539
 540         usbi_dbg("active bLength %d", ucd.ucd_desc.bLength);
 541
 542         len = UGETW(ucd.ucd_desc.wTotalLength);
 543         buf = malloc(len);
 544         if (buf == NULL)
 545                 return (LIBUSB_ERROR_NO_MEM);
 546
 547         ufd.ufd_config_index = ucd.ucd_config_index;
 548         ufd.ufd_size = len;
 549         ufd.ufd_data = buf;
 550
 551         usbi_dbg("index %d, len %d", ufd.ufd_config_index, len);
 552
 553         if ((ioctl(fd, USB_GET_FULL_DESC, &ufd)) < 0) {
 554                 free(buf);
 555                 return _errno_to_libusb(errno);
 556         }
 557
 558         if (dpriv->cdesc)
 559                 free(dpriv->cdesc);
 560         dpriv->cdesc = buf;
 561
 562         return (0);
 563 }
 564
 565 int
 566 _sync_control_transfer(struct usbi_transfer *itransfer)
 567 {
 568         struct libusb_transfer *transfer;
 569         struct libusb_control_setup *setup;
 570         struct device_priv *dpriv;
 571         struct usb_ctl_request req;
 572
 573         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 574         dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;
 575         setup = (struct libusb_control_setup *)transfer->buffer;
 576
 577         usbi_dbg("type %d request %d value %d index %d length %d timeout %d",
 578             setup->bmRequestType, setup->bRequest,
 579             libusb_le16_to_cpu(setup->wValue),
 580             libusb_le16_to_cpu(setup->wIndex),
 581             libusb_le16_to_cpu(setup->wLength), transfer->timeout);
 582
 583         req.ucr_request.bmRequestType = setup->bmRequestType;
 584         req.ucr_request.bRequest = setup->bRequest;
 585         /* Don't use USETW, libusb already deals with the endianness */
 586         (*(uint16_t *)req.ucr_request.wValue) = setup->wValue;
 587         (*(uint16_t *)req.ucr_request.wIndex) = setup->wIndex;
 588         (*(uint16_t *)req.ucr_request.wLength) = setup->wLength;
 589         req.ucr_data = transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE;
 590
 591         if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
 592                 req.ucr_flags = USBD_SHORT_XFER_OK;
 593
 594         if ((ioctl(dpriv->fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
 595                 return _errno_to_libusb(errno);
 596
 597         if ((ioctl(dpriv->fd, USB_DO_REQUEST, &req)) < 0)
 598                 return _errno_to_libusb(errno);
 599
 600         itransfer->transferred = req.ucr_actlen;
 601
 602         usbi_dbg("transferred %d", itransfer->transferred);
 603
 604         return (0);
 605 }
 606
 607 int
 608 _access_endpoint(struct libusb_transfer *transfer)
 609 {
 610         struct handle_priv *hpriv;
 611         struct device_priv *dpriv;
 612         char *s, devnode[16];
 613         int fd, endpt;
 614         mode_t mode;
 615
 616         hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;
 617         dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;
 618
 619         endpt = UE_GET_ADDR(transfer->endpoint);
 620         mode = IS_XFERIN(transfer) ? O_RDONLY : O_WRONLY;
 621
 622         usbi_dbg("endpoint %d mode %d", endpt, mode);
 623
 624         if (hpriv->endpoints[endpt] < 0) {
 625                 /* Pick the right node given the control one */
 626                 strlcpy(devnode, dpriv->devnode, sizeof(devnode));
 627                 s = strchr(devnode, '.');
 628                 snprintf(s, 4, ".%02d", endpt);
 629
 630                 /* We may need to read/write to the same endpoint later. */
 631                 if (((fd = open(devnode, O_RDWR)) < 0) && (errno == ENXIO))
 632                         if ((fd = open(devnode, mode)) < 0)
 633                                 return (-1);
 634
 635                 hpriv->endpoints[endpt] = fd;
 636         }
 637
 638         return (hpriv->endpoints[endpt]);
 639 }
 640
 641 int
 642 _sync_gen_transfer(struct usbi_transfer *itransfer)
 643 {
 644         struct libusb_transfer *transfer;
 645         int fd, nr = 1;
 646
 647         transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 648
 649         /*
 650          * Bulk, Interrupt or Isochronous transfer depends on the
 651          * endpoint and thus the node to open.
 652          */
 653         if ((fd = _access_endpoint(transfer)) < 0)
 654                 return _errno_to_libusb(errno);
 655
 656         if ((ioctl(fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
 657                 return _errno_to_libusb(errno);
 658
 659         if (IS_XFERIN(transfer)) {
 660                 if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
 661                         if ((ioctl(fd, USB_SET_SHORT_XFER, &nr)) < 0)
 662                                 return _errno_to_libusb(errno);
 663
 664                 nr = read(fd, transfer->buffer, transfer->length);
 665         } else {
 666                 nr = write(fd, transfer->buffer, transfer->length);
 667         }
 668
 669         if (nr < 0)
 670                 return _errno_to_libusb(errno);
 671
 672         itransfer->transferred = nr;
 673
 674         return (0);
 675 }