lib/libusb/libusb20_desc.c

   1 /* $FreeBSD$ */
   2 /*-
   3  * Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/queue.h>
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #include "libusb20.h"
  34 #include "libusb20_desc.h"
  35 #include "libusb20_int.h"
  36
  37 static const uint32_t libusb20_me_encode_empty[2];      /* dummy */
  38
  39 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_DEVICE_DESC);
  40 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_ENDPOINT_DESC);
  41 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_INTERFACE_DESC);
  42 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONFIG_DESC);
  43 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONTROL_SETUP);
  44 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_ENDPT_COMP_DESC);
  45 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_USB_20_DEVCAP_DESC);
  46 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_USB_DEVCAP_DESC);
  47 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_BOS_DESCRIPTOR);
  48
  49 /*------------------------------------------------------------------------*
  50  *      libusb20_parse_config_desc
  51  *
  52  * Return values:
  53  * NULL: Out of memory.
  54  * Else: A valid config structure pointer which must be passed to "free()"
  55  *------------------------------------------------------------------------*/
  56 struct libusb20_config *
  57 libusb20_parse_config_desc(const void *config_desc)
  58 {
  59         struct libusb20_config *lub_config;
  60         struct libusb20_interface *lub_interface;
  61         struct libusb20_interface *lub_alt_interface;
  62         struct libusb20_interface *last_if;
  63         struct libusb20_endpoint *lub_endpoint;
  64         struct libusb20_endpoint *last_ep;
  65
  66         struct libusb20_me_struct pcdesc;
  67         const uint8_t *ptr;
  68         uint32_t size;
  69         uint16_t niface_no_alt;
  70         uint16_t niface;
  71         uint16_t nendpoint;
  72         uint8_t iface_no;
  73
  74         ptr = config_desc;
  75         if (ptr[1] != LIBUSB20_DT_CONFIG) {
  76                 return (NULL);          /* not config descriptor */
  77         }
  78         /*
  79          * The first "bInterfaceNumber" should never have the value 0xff.
  80          * Then it is corrupt.
  81          */
  82         niface_no_alt = 0;
  83         nendpoint = 0;
  84         niface = 0;
  85         iface_no = 0 - 1;
  86         ptr = NULL;
  87
  88         /* get "wTotalLength" and setup "pcdesc" */
  89         pcdesc.ptr = LIBUSB20_ADD_BYTES(config_desc, 0);
  90         pcdesc.len =
  91             ((const uint8_t *)config_desc)[2] |
  92             (((const uint8_t *)config_desc)[3] << 8);
  93         pcdesc.type = LIBUSB20_ME_IS_RAW;
  94
  95         /* descriptor pre-scan */
  96         while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) {
  97                 if (ptr[1] == LIBUSB20_DT_ENDPOINT) {
  98                         nendpoint++;
  99                 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) {
 100                         niface++;
 101                         /* check "bInterfaceNumber" */
 102                         if (ptr[2] != iface_no) {
 103                                 iface_no = ptr[2];
 104                                 niface_no_alt++;
 105                         }
 106                 }
 107         }
 108
 109         /* sanity checking */
 110         if (niface >= 256) {
 111                 return (NULL);          /* corrupt */
 112         }
 113         if (nendpoint >= 256) {
 114                 return (NULL);          /* corrupt */
 115         }
 116         size = sizeof(*lub_config) +
 117             (niface * sizeof(*lub_interface)) +
 118             (nendpoint * sizeof(*lub_endpoint)) +
 119             pcdesc.len;
 120
 121         lub_config = malloc(size);
 122         if (lub_config == NULL) {
 123                 return (NULL);          /* out of memory */
 124         }
 125         /* make sure memory is initialised */
 126         memset(lub_config, 0, size);
 127
 128         lub_interface = (void *)(lub_config + 1);
 129         lub_alt_interface = (void *)(lub_interface + niface_no_alt);
 130         lub_endpoint = (void *)(lub_interface + niface);
 131
 132         /*
 133          * Make a copy of the config descriptor, so that the caller can free
 134          * the inital config descriptor pointer!
 135          */
 136         ptr = (void *)(lub_endpoint + nendpoint);
 137         memcpy(LIBUSB20_ADD_BYTES(ptr, 0), config_desc, pcdesc.len);
 138         pcdesc.ptr = LIBUSB20_ADD_BYTES(ptr, 0);
 139         config_desc = LIBUSB20_ADD_BYTES(ptr, 0);
 140
 141         /* init config structure */
 142
 143         ptr = config_desc;
 144
 145         LIBUSB20_INIT(LIBUSB20_CONFIG_DESC, &lub_config->desc);
 146
 147         if (libusb20_me_decode(ptr, ptr[0], &lub_config->desc)) {
 148                 /* ignore */
 149         }
 150         lub_config->num_interface = 0;
 151         lub_config->interface = lub_interface;
 152         lub_config->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 153         lub_config->extra.len = -ptr[0];
 154         lub_config->extra.type = LIBUSB20_ME_IS_RAW;
 155
 156         /* reset states */
 157         niface = 0;
 158         iface_no = 0 - 1;
 159         ptr = NULL;
 160         lub_interface--;
 161         lub_endpoint--;
 162         last_if = NULL;
 163         last_ep = NULL;
 164
 165         /* descriptor pre-scan */
 166         while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) {
 167                 if (ptr[1] == LIBUSB20_DT_ENDPOINT) {
 168                         if (last_if) {
 169                                 lub_endpoint++;
 170                                 last_ep = lub_endpoint;
 171                                 last_if->num_endpoints++;
 172
 173                                 LIBUSB20_INIT(LIBUSB20_ENDPOINT_DESC, &last_ep->desc);
 174
 175                                 if (libusb20_me_decode(ptr, ptr[0], &last_ep->desc)) {
 176                                         /* ignore */
 177                                 }
 178                                 last_ep->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 179                                 last_ep->extra.len = 0;
 180                                 last_ep->extra.type = LIBUSB20_ME_IS_RAW;
 181                         } else {
 182                                 lub_config->extra.len += ptr[0];
 183                         }
 184
 185                 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) {
 186                         if (ptr[2] != iface_no) {
 187                                 /* new interface */
 188                                 iface_no = ptr[2];
 189                                 lub_interface++;
 190                                 lub_config->num_interface++;
 191                                 last_if = lub_interface;
 192                                 niface++;
 193                         } else {
 194                                 /* one more alternate setting */
 195                                 lub_interface->num_altsetting++;
 196                                 last_if = lub_alt_interface;
 197                                 lub_alt_interface++;
 198                         }
 199
 200                         LIBUSB20_INIT(LIBUSB20_INTERFACE_DESC, &last_if->desc);
 201
 202                         if (libusb20_me_decode(ptr, ptr[0], &last_if->desc)) {
 203                                 /* ignore */
 204                         }
 205                         /*
 206                          * Sometimes USB devices have corrupt interface
 207                          * descriptors and we need to overwrite the provided
 208                          * interface number!
 209                          */
 210                         last_if->desc.bInterfaceNumber = niface - 1;
 211                         last_if->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 212                         last_if->extra.len = 0;
 213                         last_if->extra.type = LIBUSB20_ME_IS_RAW;
 214                         last_if->endpoints = lub_endpoint + 1;
 215                         last_if->altsetting = lub_alt_interface;
 216                         last_if->num_altsetting = 0;
 217                         last_if->num_endpoints = 0;
 218                         last_ep = NULL;
 219                 } else {
 220                         /* unknown descriptor */
 221                         if (last_if) {
 222                                 if (last_ep) {
 223                                         last_ep->extra.len += ptr[0];
 224                                 } else {
 225                                         last_if->extra.len += ptr[0];
 226                                 }
 227                         } else {
 228                                 lub_config->extra.len += ptr[0];
 229                         }
 230                 }
 231         }
 232         return (lub_config);
 233 }
 234
 235 /*------------------------------------------------------------------------*
 236  *      libusb20_desc_foreach
 237  *
 238  * Safe traversal of USB descriptors.
 239  *
 240  * Return values:
 241  * NULL: End of descriptors
 242  * Else: Pointer to next descriptor
 243  *------------------------------------------------------------------------*/
 244 const uint8_t *
 245 libusb20_desc_foreach(const struct libusb20_me_struct *pdesc,
 246     const uint8_t *psubdesc)
 247 {
 248         const uint8_t *start;
 249         const uint8_t *end;
 250         const uint8_t *desc_next;
 251
 252         /* be NULL safe */
 253         if (pdesc == NULL)
 254                 return (NULL);
 255
 256         start = (const uint8_t *)pdesc->ptr;
 257         end = LIBUSB20_ADD_BYTES(start, pdesc->len);
 258
 259         /* get start of next descriptor */
 260         if (psubdesc == NULL)
 261                 psubdesc = start;
 262         else
 263                 psubdesc = psubdesc + psubdesc[0];
 264
 265         /* check that the next USB descriptor is within the range */
 266         if ((psubdesc < start) || (psubdesc >= end))
 267                 return (NULL);          /* out of range, or EOD */
 268
 269         /* check start of the second next USB descriptor, if any */
 270         desc_next = psubdesc + psubdesc[0];
 271         if ((desc_next < start) || (desc_next > end))
 272                 return (NULL);          /* out of range */
 273
 274         /* check minimum descriptor length */
 275         if (psubdesc[0] < 3)
 276                 return (NULL);          /* too short descriptor */
 277
 278         return (psubdesc);              /* return start of next descriptor */
 279 }
 280
 281 /*------------------------------------------------------------------------*
 282  *      libusb20_me_get_1 - safety wrapper to read out one byte
 283  *------------------------------------------------------------------------*/
 284 uint8_t
 285 libusb20_me_get_1(const struct libusb20_me_struct *ie, uint16_t offset)
 286 {
 287         if (offset < ie->len) {
 288                 return (*((uint8_t *)LIBUSB20_ADD_BYTES(ie->ptr, offset)));
 289         }
 290         return (0);
 291 }
 292
 293 /*------------------------------------------------------------------------*
 294  *      libusb20_me_get_2 - safety wrapper to read out one word
 295  *------------------------------------------------------------------------*/
 296 uint16_t
 297 libusb20_me_get_2(const struct libusb20_me_struct *ie, uint16_t offset)
 298 {
 299         return (libusb20_me_get_1(ie, offset) |
 300             (libusb20_me_get_1(ie, offset + 1) << 8));
 301 }
 302
 303 /*------------------------------------------------------------------------*
 304  *      libusb20_me_encode - encode a message structure
 305  *
 306  * Description of parameters:
 307  * "len" - maximum length of output buffer
 308  * "ptr" - pointer to output buffer. If NULL, no data will be written
 309  * "pd" - source structure
 310  *
 311  * Return values:
 312  * 0..65535 - Number of bytes used, limited by the "len" input parameter.
 313  *------------------------------------------------------------------------*/
 314 uint16_t
 315 libusb20_me_encode(void *ptr, uint16_t len, const void *pd)
 316 {
 317         const uint8_t *pf;              /* pointer to format data */
 318         uint8_t *buf;                   /* pointer to output buffer */
 319
 320         uint32_t pd_offset;             /* decoded structure offset */
 321         uint16_t len_old;               /* old length */
 322         uint16_t pd_count;              /* decoded element count */
 323         uint8_t me;                     /* message element */
 324
 325         /* initialise */
 326
 327         len_old = len;
 328         buf = ptr;
 329         pd_offset = sizeof(void *);
 330         pf = (*((struct libusb20_me_format *const *)pd))->format;
 331
 332         /* scan */
 333
 334         while (1) {
 335
 336                 /* get information element */
 337
 338                 me = (pf[0]) & LIBUSB20_ME_MASK;
 339                 pd_count = pf[1] | (pf[2] << 8);
 340                 pf += 3;
 341
 342                 /* encode the message element */
 343
 344                 switch (me) {
 345                 case LIBUSB20_ME_INT8:
 346                         while (pd_count--) {
 347                                 uint8_t temp;
 348
 349                                 if (len < 1)    /* overflow */
 350                                         goto done;
 351                                 if (buf) {
 352                                         temp = *((const uint8_t *)
 353                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 354                                         buf[0] = temp;
 355                                         buf += 1;
 356                                 }
 357                                 pd_offset += 1;
 358                                 len -= 1;
 359                         }
 360                         break;
 361
 362                 case LIBUSB20_ME_INT16:
 363                         pd_offset = -((-pd_offset) & ~1);       /* align */
 364                         while (pd_count--) {
 365                                 uint16_t temp;
 366
 367                                 if (len < 2)    /* overflow */
 368                                         goto done;
 369
 370                                 if (buf) {
 371                                         temp = *((const uint16_t *)
 372                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 373                                         buf[1] = (temp >> 8) & 0xFF;
 374                                         buf[0] = temp & 0xFF;
 375                                         buf += 2;
 376                                 }
 377                                 pd_offset += 2;
 378                                 len -= 2;
 379                         }
 380                         break;
 381
 382                 case LIBUSB20_ME_INT32:
 383                         pd_offset = -((-pd_offset) & ~3);       /* align */
 384                         while (pd_count--) {
 385                                 uint32_t temp;
 386
 387                                 if (len < 4)    /* overflow */
 388                                         goto done;
 389                                 if (buf) {
 390                                         temp = *((const uint32_t *)
 391                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 392                                         buf[3] = (temp >> 24) & 0xFF;
 393                                         buf[2] = (temp >> 16) & 0xFF;
 394                                         buf[1] = (temp >> 8) & 0xFF;
 395                                         buf[0] = temp & 0xFF;
 396                                         buf += 4;
 397                                 }
 398                                 pd_offset += 4;
 399                                 len -= 4;
 400                         }
 401                         break;
 402
 403                 case LIBUSB20_ME_INT64:
 404                         pd_offset = -((-pd_offset) & ~7);       /* align */
 405                         while (pd_count--) {
 406                                 uint64_t temp;
 407
 408                                 if (len < 8)    /* overflow */
 409                                         goto done;
 410                                 if (buf) {
 411
 412                                         temp = *((const uint64_t *)
 413                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 414                                         buf[7] = (temp >> 56) & 0xFF;
 415                                         buf[6] = (temp >> 48) & 0xFF;
 416                                         buf[5] = (temp >> 40) & 0xFF;
 417                                         buf[4] = (temp >> 32) & 0xFF;
 418                                         buf[3] = (temp >> 24) & 0xFF;
 419                                         buf[2] = (temp >> 16) & 0xFF;
 420                                         buf[1] = (temp >> 8) & 0xFF;
 421                                         buf[0] = temp & 0xFF;
 422                                         buf += 8;
 423                                 }
 424                                 pd_offset += 8;
 425                                 len -= 8;
 426                         }
 427                         break;
 428
 429                 case LIBUSB20_ME_STRUCT:
 430                         pd_offset = -((-pd_offset) &
 431                             ~(LIBUSB20_ME_STRUCT_ALIGN - 1));   /* align */
 432                         while (pd_count--) {
 433                                 void *src_ptr;
 434                                 uint16_t src_len;
 435                                 struct libusb20_me_struct *ps;
 436
 437                                 ps = LIBUSB20_ADD_BYTES(pd, pd_offset);
 438
 439                                 switch (ps->type) {
 440                                 case LIBUSB20_ME_IS_RAW:
 441                                         src_len = ps->len;
 442                                         src_ptr = ps->ptr;
 443                                         break;
 444
 445                                 case LIBUSB20_ME_IS_ENCODED:
 446                                         if (ps->len == 0) {
 447                                                 /*
 448                                                  * Length is encoded
 449                                                  * in the data itself
 450                                                  * and should be
 451                                                  * correct:
 452                                                  */
 453                                                 ps->len = 0 - 1;
 454                                         }
 455                                         src_len = libusb20_me_get_1(pd, 0);
 456                                         src_ptr = LIBUSB20_ADD_BYTES(ps->ptr, 1);
 457                                         if (src_len == 0xFF) {
 458                                                 /* length is escaped */
 459                                                 src_len = libusb20_me_get_2(pd, 1);
 460                                                 src_ptr =
 461                                                     LIBUSB20_ADD_BYTES(ps->ptr, 3);
 462                                         }
 463                                         break;
 464
 465                                 case LIBUSB20_ME_IS_DECODED:
 466                                         /* reserve 3 length bytes */
 467                                         src_len = libusb20_me_encode(NULL,
 468                                             0 - 1 - 3, ps->ptr);
 469                                         src_ptr = NULL;
 470                                         break;
 471
 472                                 default:        /* empty structure */
 473                                         src_len = 0;
 474                                         src_ptr = NULL;
 475                                         break;
 476                                 }
 477
 478                                 if (src_len > 0xFE) {
 479                                         if (src_len > (uint16_t)(0 - 1 - 3))
 480                                                 /* overflow */
 481                                                 goto done;
 482
 483                                         if (len < (src_len + 3))
 484                                                 /* overflow */
 485                                                 goto done;
 486
 487                                         if (buf) {
 488                                                 buf[0] = 0xFF;
 489                                                 buf[1] = (src_len & 0xFF);
 490                                                 buf[2] = (src_len >> 8) & 0xFF;
 491                                                 buf += 3;
 492                                         }
 493                                         len -= (src_len + 3);
 494                                 } else {
 495                                         if (len < (src_len + 1))
 496                                                 /* overflow */
 497                                                 goto done;
 498
 499                                         if (buf) {
 500                                                 buf[0] = (src_len & 0xFF);
 501                                                 buf += 1;
 502                                         }
 503                                         len -= (src_len + 1);
 504                                 }
 505
 506                                 /* check for buffer and non-zero length */
 507
 508                                 if (buf && src_len) {
 509                                         if (ps->type == LIBUSB20_ME_IS_DECODED) {
 510                                                 /*
 511                                                  * Repeat encode
 512                                                  * procedure - we have
 513                                                  * room for the
 514                                                  * complete structure:
 515                                                  */
 516                                                 uint16_t dummy;
 517
 518                                                 dummy = libusb20_me_encode(buf,
 519                                                     0 - 1 - 3, ps->ptr);
 520                                         } else {
 521                                                 bcopy(src_ptr, buf, src_len);
 522                                         }
 523                                         buf += src_len;
 524                                 }
 525                                 pd_offset += sizeof(struct libusb20_me_struct);
 526                         }
 527                         break;
 528
 529                 default:
 530                         goto done;
 531                 }
 532         }
 533 done:
 534         return (len_old - len);
 535 }
 536
 537 /*------------------------------------------------------------------------*
 538  *      libusb20_me_decode - decode a message into a decoded structure
 539  *
 540  * Description of parameters:
 541  * "ptr" - message pointer
 542  * "len" - message length
 543  * "pd" - pointer to decoded structure
 544  *
 545  * Returns:
 546  * "0..65535" - number of bytes decoded, limited by "len"
 547  *------------------------------------------------------------------------*/
 548 uint16_t
 549 libusb20_me_decode(const void *ptr, uint16_t len, void *pd)
 550 {
 551         const uint8_t *pf;              /* pointer to format data */
 552         const uint8_t *buf;             /* pointer to input buffer */
 553
 554         uint32_t pd_offset;             /* decoded structure offset */
 555         uint16_t len_old;               /* old length */
 556         uint16_t pd_count;              /* decoded element count */
 557         uint8_t me;                     /* message element */
 558
 559         /* initialise */
 560
 561         len_old = len;
 562         buf = ptr;
 563         pd_offset = sizeof(void *);
 564         pf = (*((struct libusb20_me_format **)pd))->format;
 565
 566         /* scan */
 567
 568         while (1) {
 569
 570                 /* get information element */
 571
 572                 me = (pf[0]) & LIBUSB20_ME_MASK;
 573                 pd_count = pf[1] | (pf[2] << 8);
 574                 pf += 3;
 575
 576                 /* decode the message element by type */
 577
 578                 switch (me) {
 579                 case LIBUSB20_ME_INT8:
 580                         while (pd_count--) {
 581                                 uint8_t temp;
 582
 583                                 if (len < 1) {
 584                                         len = 0;
 585                                         temp = 0;
 586                                 } else {
 587                                         len -= 1;
 588                                         temp = buf[0];
 589                                         buf++;
 590                                 }
 591                                 *((uint8_t *)LIBUSB20_ADD_BYTES(pd,
 592                                     pd_offset)) = temp;
 593                                 pd_offset += 1;
 594                         }
 595                         break;
 596
 597                 case LIBUSB20_ME_INT16:
 598                         pd_offset = -((-pd_offset) & ~1);       /* align */
 599                         while (pd_count--) {
 600                                 uint16_t temp;
 601
 602                                 if (len < 2) {
 603                                         len = 0;
 604                                         temp = 0;
 605                                 } else {
 606                                         len -= 2;
 607                                         temp = buf[1] << 8;
 608                                         temp |= buf[0];
 609                                         buf += 2;
 610                                 }
 611                                 *((uint16_t *)LIBUSB20_ADD_BYTES(pd,
 612                                     pd_offset)) = temp;
 613                                 pd_offset += 2;
 614                         }
 615                         break;
 616
 617                 case LIBUSB20_ME_INT32:
 618                         pd_offset = -((-pd_offset) & ~3);       /* align */
 619                         while (pd_count--) {
 620                                 uint32_t temp;
 621
 622                                 if (len < 4) {
 623                                         len = 0;
 624                                         temp = 0;
 625                                 } else {
 626                                         len -= 4;
 627                                         temp = buf[3] << 24;
 628                                         temp |= buf[2] << 16;
 629                                         temp |= buf[1] << 8;
 630                                         temp |= buf[0];
 631                                         buf += 4;
 632                                 }
 633
 634                                 *((uint32_t *)LIBUSB20_ADD_BYTES(pd,
 635                                     pd_offset)) = temp;
 636                                 pd_offset += 4;
 637                         }
 638                         break;
 639
 640                 case LIBUSB20_ME_INT64:
 641                         pd_offset = -((-pd_offset) & ~7);       /* align */
 642                         while (pd_count--) {
 643                                 uint64_t temp;
 644
 645                                 if (len < 8) {
 646                                         len = 0;
 647                                         temp = 0;
 648                                 } else {
 649                                         len -= 8;
 650                                         temp = ((uint64_t)buf[7]) << 56;
 651                                         temp |= ((uint64_t)buf[6]) << 48;
 652                                         temp |= ((uint64_t)buf[5]) << 40;
 653                                         temp |= ((uint64_t)buf[4]) << 32;
 654                                         temp |= buf[3] << 24;
 655                                         temp |= buf[2] << 16;
 656                                         temp |= buf[1] << 8;
 657                                         temp |= buf[0];
 658                                         buf += 8;
 659                                 }
 660
 661                                 *((uint64_t *)LIBUSB20_ADD_BYTES(pd,
 662                                     pd_offset)) = temp;
 663                                 pd_offset += 8;
 664                         }
 665                         break;
 666
 667                 case LIBUSB20_ME_STRUCT:
 668                         pd_offset = -((-pd_offset) &
 669                             ~(LIBUSB20_ME_STRUCT_ALIGN - 1));   /* align */
 670                         while (pd_count--) {
 671                                 uint16_t temp;
 672                                 uint16_t dummy;
 673                                 struct libusb20_me_struct *ps;
 674
 675                                 ps = LIBUSB20_ADD_BYTES(pd, pd_offset);
 676
 677                                 if (ps->type == LIBUSB20_ME_IS_ENCODED) {
 678                                         /*
 679                                          * Pre-store a de-constified
 680                                          * pointer to the raw
 681                                          * structure:
 682                                          */
 683                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 684
 685                                         /*
 686                                          * Get the correct number of
 687                                          * length bytes:
 688                                          */
 689                                         if (len != 0) {
 690                                                 if (buf[0] == 0xFF) {
 691                                                         ps->len = 3;
 692                                                 } else {
 693                                                         ps->len = 1;
 694                                                 }
 695                                         } else {
 696                                                 ps->len = 0;
 697                                         }
 698                                 }
 699                                 /* get the structure length */
 700
 701                                 if (len != 0) {
 702                                         if (buf[0] == 0xFF) {
 703                                                 if (len < 3) {
 704                                                         len = 0;
 705                                                         temp = 0;
 706                                                 } else {
 707                                                         len -= 3;
 708                                                         temp = buf[1] |
 709                                                             (buf[2] << 8);
 710                                                         buf += 3;
 711                                                 }
 712                                         } else {
 713                                                 len -= 1;
 714                                                 temp = buf[0];
 715                                                 buf += 1;
 716                                         }
 717                                 } else {
 718                                         len = 0;
 719                                         temp = 0;
 720                                 }
 721                                 /* check for invalid length */
 722
 723                                 if (temp > len) {
 724                                         len = 0;
 725                                         temp = 0;
 726                                 }
 727                                 /* check wanted structure type */
 728
 729                                 switch (ps->type) {
 730                                 case LIBUSB20_ME_IS_ENCODED:
 731                                         /* check for zero length */
 732                                         if (temp == 0) {
 733                                                 /*
 734                                                  * The pointer must
 735                                                  * be valid:
 736                                                  */
 737                                                 ps->ptr = LIBUSB20_ADD_BYTES(
 738                                                     libusb20_me_encode_empty, 0);
 739                                                 ps->len = 1;
 740                                         } else {
 741                                                 ps->len += temp;
 742                                         }
 743                                         break;
 744
 745                                 case LIBUSB20_ME_IS_RAW:
 746                                         /* update length and pointer */
 747                                         ps->len = temp;
 748                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 749                                         break;
 750
 751                                 case LIBUSB20_ME_IS_EMPTY:
 752                                 case LIBUSB20_ME_IS_DECODED:
 753                                         /* check for non-zero length */
 754                                         if (temp != 0) {
 755                                                 /* update type */
 756                                                 ps->type = LIBUSB20_ME_IS_DECODED;
 757                                                 ps->len = 0;
 758                                                 /*
 759                                                  * Recursivly decode
 760                                                  * the next structure
 761                                                  */
 762                                                 dummy = libusb20_me_decode(buf,
 763                                                     temp, ps->ptr);
 764                                         } else {
 765                                                 /* update type */
 766                                                 ps->type = LIBUSB20_ME_IS_EMPTY;
 767                                                 ps->len = 0;
 768                                         }
 769                                         break;
 770
 771                                 default:
 772                                         /*
 773                                          * nothing to do - should
 774                                          * not happen
 775                                          */
 776                                         ps->ptr = NULL;
 777                                         ps->len = 0;
 778                                         break;
 779                                 }
 780                                 buf += temp;
 781                                 len -= temp;
 782                                 pd_offset += sizeof(struct libusb20_me_struct);
 783                         }
 784                         break;
 785
 786                 default:
 787                         goto done;
 788                 }
 789         }
 790 done:
 791         return (len_old - len);
 792 }