linux/tools/usb/ffs-test.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * ffs-test.c -- user mode filesystem api for usb composite function
   4 *
   5 * Copyright (C) 2010 Samsung Electronics
   6 *                    Author: Michal Nazarewicz <mina86@mina86.com>
   7 */
   8
   9/* $(CROSS_COMPILE)cc -Wall -Wextra -g -o ffs-test ffs-test.c -lpthread */
  10
  11
  12#define _DEFAULT_SOURCE /* for endian.h */
  13
  14#include <endian.h>
  15#include <errno.h>
  16#include <fcntl.h>
  17#include <pthread.h>
  18#include <stdarg.h>
  19#include <stdbool.h>
  20#include <stdio.h>
  21#include <stdlib.h>
  22#include <string.h>
  23#include <sys/ioctl.h>
  24#include <sys/stat.h>
  25#include <sys/types.h>
  26#include <unistd.h>
  27#include <tools/le_byteshift.h>
  28
  29#include "../../include/uapi/linux/usb/functionfs.h"
  30
  31
  32/******************** Little Endian Handling ********************************/
  33
  34/*
  35 * cpu_to_le16/32 are used when initializing structures, a context where a
  36 * function call is not allowed. To solve this, we code cpu_to_le16/32 in a way
  37 * that allows them to be used when initializing structures.
  38 */
  39
  40#if __BYTE_ORDER == __LITTLE_ENDIAN
  41#define cpu_to_le16(x)  (x)
  42#define cpu_to_le32(x)  (x)
  43#else
  44#define cpu_to_le16(x)  ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
  45#define cpu_to_le32(x)  \
  46        ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) | \
  47        (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
  48#endif
  49
  50#define le32_to_cpu(x)  le32toh(x)
  51#define le16_to_cpu(x)  le16toh(x)
  52
  53/******************** Messages and Errors ***********************************/
  54
  55static const char argv0[] = "ffs-test";
  56
  57static unsigned verbosity = 7;
  58
  59static void _msg(unsigned level, const char *fmt, ...)
  60{
  61        if (level < 2)
  62                level = 2;
  63        else if (level > 7)
  64                level = 7;
  65
  66        if (level <= verbosity) {
  67                static const char levels[8][6] = {
  68                        [2] = "crit:",
  69                        [3] = "err: ",
  70                        [4] = "warn:",
  71                        [5] = "note:",
  72                        [6] = "info:",
  73                        [7] = "dbg: "
  74                };
  75
  76                int _errno = errno;
  77                va_list ap;
  78
  79                fprintf(stderr, "%s: %s ", argv0, levels[level]);
  80                va_start(ap, fmt);
  81                vfprintf(stderr, fmt, ap);
  82                va_end(ap);
  83
  84                if (fmt[strlen(fmt) - 1] != '\n') {
  85                        char buffer[128];
  86                        strerror_r(_errno, buffer, sizeof buffer);
  87                        fprintf(stderr, ": (-%d) %s\n", _errno, buffer);
  88                }
  89
  90                fflush(stderr);
  91        }
  92}
  93
  94#define die(...)  (_msg(2, __VA_ARGS__), exit(1))
  95#define err(...)   _msg(3, __VA_ARGS__)
  96#define warn(...)  _msg(4, __VA_ARGS__)
  97#define note(...)  _msg(5, __VA_ARGS__)
  98#define info(...)  _msg(6, __VA_ARGS__)
  99#define debug(...) _msg(7, __VA_ARGS__)
 100
 101#define die_on(cond, ...) do { \
 102        if (cond) \
 103                die(__VA_ARGS__); \
 104        } while (0)
 105
 106
 107/******************** Descriptors and Strings *******************************/
 108
 109static const struct {
 110        struct usb_functionfs_descs_head_v2 header;
 111        __le32 fs_count;
 112        __le32 hs_count;
 113        __le32 ss_count;
 114        struct {
 115                struct usb_interface_descriptor intf;
 116                struct usb_endpoint_descriptor_no_audio sink;
 117                struct usb_endpoint_descriptor_no_audio source;
 118        } __attribute__((packed)) fs_descs, hs_descs;
 119        struct {
 120                struct usb_interface_descriptor intf;
 121                struct usb_endpoint_descriptor_no_audio sink;
 122                struct usb_ss_ep_comp_descriptor sink_comp;
 123                struct usb_endpoint_descriptor_no_audio source;
 124                struct usb_ss_ep_comp_descriptor source_comp;
 125        } ss_descs;
 126} __attribute__((packed)) descriptors = {
 127        .header = {
 128                .magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
 129                .flags = cpu_to_le32(FUNCTIONFS_HAS_FS_DESC |
 130                                     FUNCTIONFS_HAS_HS_DESC |
 131                                     FUNCTIONFS_HAS_SS_DESC),
 132                .length = cpu_to_le32(sizeof descriptors),
 133        },
 134        .fs_count = cpu_to_le32(3),
 135        .fs_descs = {
 136                .intf = {
 137                        .bLength = sizeof descriptors.fs_descs.intf,
 138                        .bDescriptorType = USB_DT_INTERFACE,
 139                        .bNumEndpoints = 2,
 140                        .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
 141                        .iInterface = 1,
 142                },
 143                .sink = {
 144                        .bLength = sizeof descriptors.fs_descs.sink,
 145                        .bDescriptorType = USB_DT_ENDPOINT,
 146                        .bEndpointAddress = 1 | USB_DIR_IN,
 147                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 148                        /* .wMaxPacketSize = autoconfiguration (kernel) */
 149                },
 150                .source = {
 151                        .bLength = sizeof descriptors.fs_descs.source,
 152                        .bDescriptorType = USB_DT_ENDPOINT,
 153                        .bEndpointAddress = 2 | USB_DIR_OUT,
 154                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 155                        /* .wMaxPacketSize = autoconfiguration (kernel) */
 156                },
 157        },
 158        .hs_count = cpu_to_le32(3),
 159        .hs_descs = {
 160                .intf = {
 161                        .bLength = sizeof descriptors.fs_descs.intf,
 162                        .bDescriptorType = USB_DT_INTERFACE,
 163                        .bNumEndpoints = 2,
 164                        .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
 165                        .iInterface = 1,
 166                },
 167                .sink = {
 168                        .bLength = sizeof descriptors.hs_descs.sink,
 169                        .bDescriptorType = USB_DT_ENDPOINT,
 170                        .bEndpointAddress = 1 | USB_DIR_IN,
 171                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 172                        .wMaxPacketSize = cpu_to_le16(512),
 173                },
 174                .source = {
 175                        .bLength = sizeof descriptors.hs_descs.source,
 176                        .bDescriptorType = USB_DT_ENDPOINT,
 177                        .bEndpointAddress = 2 | USB_DIR_OUT,
 178                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 179                        .wMaxPacketSize = cpu_to_le16(512),
 180                        .bInterval = 1, /* NAK every 1 uframe */
 181                },
 182        },
 183        .ss_count = cpu_to_le32(5),
 184        .ss_descs = {
 185                .intf = {
 186                        .bLength = sizeof descriptors.fs_descs.intf,
 187                        .bDescriptorType = USB_DT_INTERFACE,
 188                        .bNumEndpoints = 2,
 189                        .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
 190                        .iInterface = 1,
 191                },
 192                .sink = {
 193                        .bLength = sizeof descriptors.hs_descs.sink,
 194                        .bDescriptorType = USB_DT_ENDPOINT,
 195                        .bEndpointAddress = 1 | USB_DIR_IN,
 196                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 197                        .wMaxPacketSize = cpu_to_le16(1024),
 198                },
 199                .sink_comp = {
 200                        .bLength = USB_DT_SS_EP_COMP_SIZE,
 201                        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
 202                        .bMaxBurst = 0,
 203                        .bmAttributes = 0,
 204                        .wBytesPerInterval = 0,
 205                },
 206                .source = {
 207                        .bLength = sizeof descriptors.hs_descs.source,
 208                        .bDescriptorType = USB_DT_ENDPOINT,
 209                        .bEndpointAddress = 2 | USB_DIR_OUT,
 210                        .bmAttributes = USB_ENDPOINT_XFER_BULK,
 211                        .wMaxPacketSize = cpu_to_le16(1024),
 212                        .bInterval = 1, /* NAK every 1 uframe */
 213                },
 214                .source_comp = {
 215                        .bLength = USB_DT_SS_EP_COMP_SIZE,
 216                        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
 217                        .bMaxBurst = 0,
 218                        .bmAttributes = 0,
 219                        .wBytesPerInterval = 0,
 220                },
 221        },
 222};
 223
 224static size_t descs_to_legacy(void **legacy, const void *descriptors_v2)
 225{
 226        const unsigned char *descs_end, *descs_start;
 227        __u32 length, fs_count = 0, hs_count = 0, count;
 228
 229        /* Read v2 header */
 230        {
 231                const struct {
 232                        const struct usb_functionfs_descs_head_v2 header;
 233                        const __le32 counts[];
 234                } __attribute__((packed)) *const in = descriptors_v2;
 235                const __le32 *counts = in->counts;
 236                __u32 flags;
 237
 238                if (le32_to_cpu(in->header.magic) !=
 239                    FUNCTIONFS_DESCRIPTORS_MAGIC_V2)
 240                        return 0;
 241                length = le32_to_cpu(in->header.length);
 242                if (length <= sizeof in->header)
 243                        return 0;
 244                length -= sizeof in->header;
 245                flags = le32_to_cpu(in->header.flags);
 246                if (flags & ~(FUNCTIONFS_HAS_FS_DESC | FUNCTIONFS_HAS_HS_DESC |
 247                              FUNCTIONFS_HAS_SS_DESC))
 248                        return 0;
 249
 250#define GET_NEXT_COUNT_IF_FLAG(ret, flg) do {           \
 251                        if (!(flags & (flg)))           \
 252                                break;                  \
 253                        if (length < 4)                 \
 254                                return 0;               \
 255                        ret = le32_to_cpu(*counts);     \
 256                        length -= 4;                    \
 257                        ++counts;                       \
 258                } while (0)
 259
 260                GET_NEXT_COUNT_IF_FLAG(fs_count, FUNCTIONFS_HAS_FS_DESC);
 261                GET_NEXT_COUNT_IF_FLAG(hs_count, FUNCTIONFS_HAS_HS_DESC);
 262                GET_NEXT_COUNT_IF_FLAG(count, FUNCTIONFS_HAS_SS_DESC);
 263
 264                count = fs_count + hs_count;
 265                if (!count)
 266                        return 0;
 267                descs_start = (const void *)counts;
 268
 269#undef GET_NEXT_COUNT_IF_FLAG
 270        }
 271
 272        /*
 273         * Find the end of FS and HS USB descriptors.  SS descriptors
 274         * are ignored since legacy format does not support them.
 275         */
 276        descs_end = descs_start;
 277        do {
 278                if (length < *descs_end)
 279                        return 0;
 280                length -= *descs_end;
 281                descs_end += *descs_end;
 282        } while (--count);
 283
 284        /* Allocate legacy descriptors and copy the data. */
 285        {
 286#pragma GCC diagnostic push
 287#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 288                struct {
 289                        struct usb_functionfs_descs_head header;
 290                        __u8 descriptors[];
 291                } __attribute__((packed)) *out;
 292#pragma GCC diagnostic pop
 293
 294                length = sizeof out->header + (descs_end - descs_start);
 295                out = malloc(length);
 296                out->header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC);
 297                out->header.length = cpu_to_le32(length);
 298                out->header.fs_count = cpu_to_le32(fs_count);
 299                out->header.hs_count = cpu_to_le32(hs_count);
 300                memcpy(out->descriptors, descs_start, descs_end - descs_start);
 301                *legacy = out;
 302        }
 303
 304        return length;
 305}
 306
 307
 308#define STR_INTERFACE_ "Source/Sink"
 309
 310static const struct {
 311        struct usb_functionfs_strings_head header;
 312        struct {
 313                __le16 code;
 314                const char str1[sizeof STR_INTERFACE_];
 315        } __attribute__((packed)) lang0;
 316} __attribute__((packed)) strings = {
 317        .header = {
 318                .magic = cpu_to_le32(FUNCTIONFS_STRINGS_MAGIC),
 319                .length = cpu_to_le32(sizeof strings),
 320                .str_count = cpu_to_le32(1),
 321                .lang_count = cpu_to_le32(1),
 322        },
 323        .lang0 = {
 324                cpu_to_le16(0x0409), /* en-us */
 325                STR_INTERFACE_,
 326        },
 327};
 328
 329#define STR_INTERFACE strings.lang0.str1
 330
 331
 332/******************** Files and Threads Handling ****************************/
 333
 334struct thread;
 335
 336static ssize_t read_wrap(struct thread *t, void *buf, size_t nbytes);
 337static ssize_t write_wrap(struct thread *t, const void *buf, size_t nbytes);
 338static ssize_t ep0_consume(struct thread *t, const void *buf, size_t nbytes);
 339static ssize_t fill_in_buf(struct thread *t, void *buf, size_t nbytes);
 340static ssize_t empty_out_buf(struct thread *t, const void *buf, size_t nbytes);
 341
 342
 343static struct thread {
 344        const char *const filename;
 345        size_t buf_size;
 346
 347        ssize_t (*in)(struct thread *, void *, size_t);
 348        const char *const in_name;
 349
 350        ssize_t (*out)(struct thread *, const void *, size_t);
 351        const char *const out_name;
 352
 353        int fd;
 354        pthread_t id;
 355        void *buf;
 356        ssize_t status;
 357} threads[] = {
 358        {
 359                "ep0", 4 * sizeof(struct usb_functionfs_event),
 360                read_wrap, NULL,
 361                ep0_consume, "<consume>",
 362                0, 0, NULL, 0
 363        },
 364        {
 365                "ep1", 8 * 1024,
 366                fill_in_buf, "<in>",
 367                write_wrap, NULL,
 368                0, 0, NULL, 0
 369        },
 370        {
 371                "ep2", 8 * 1024,
 372                read_wrap, NULL,
 373                empty_out_buf, "<out>",
 374                0, 0, NULL, 0
 375        },
 376};
 377
 378
 379static void init_thread(struct thread *t)
 380{
 381        t->buf = malloc(t->buf_size);
 382        die_on(!t->buf, "malloc");
 383
 384        t->fd = open(t->filename, O_RDWR);
 385        die_on(t->fd < 0, "%s", t->filename);
 386}
 387
 388static void cleanup_thread(void *arg)
 389{
 390        struct thread *t = arg;
 391        int ret, fd;
 392
 393        fd = t->fd;
 394        if (t->fd < 0)
 395                return;
 396        t->fd = -1;
 397
 398        /* test the FIFO ioctls (non-ep0 code paths) */
 399        if (t != threads) {
 400                ret = ioctl(fd, FUNCTIONFS_FIFO_STATUS);
 401                if (ret < 0) {
 402                        /* ENODEV reported after disconnect */
 403                        if (errno != ENODEV)
 404                                err("%s: get fifo status", t->filename);
 405                } else if (ret) {
 406                        warn("%s: unclaimed = %d\n", t->filename, ret);
 407                        if (ioctl(fd, FUNCTIONFS_FIFO_FLUSH) < 0)
 408                                err("%s: fifo flush", t->filename);
 409                }
 410        }
 411
 412        if (close(fd) < 0)
 413                err("%s: close", t->filename);
 414
 415        free(t->buf);
 416        t->buf = NULL;
 417}
 418
 419static void *start_thread_helper(void *arg)
 420{
 421        const char *name, *op, *in_name, *out_name;
 422        struct thread *t = arg;
 423        ssize_t ret;
 424
 425        info("%s: starts\n", t->filename);
 426        in_name = t->in_name ? t->in_name : t->filename;
 427        out_name = t->out_name ? t->out_name : t->filename;
 428
 429        pthread_cleanup_push(cleanup_thread, arg);
 430
 431        for (;;) {
 432                pthread_testcancel();
 433
 434                ret = t->in(t, t->buf, t->buf_size);
 435                if (ret > 0) {
 436                        ret = t->out(t, t->buf, ret);
 437                        name = out_name;
 438                        op = "write";
 439                } else {
 440                        name = in_name;
 441                        op = "read";
 442                }
 443
 444                if (ret > 0) {
 445                        /* nop */
 446                } else if (!ret) {
 447                        debug("%s: %s: EOF", name, op);
 448                        break;
 449                } else if (errno == EINTR || errno == EAGAIN) {
 450                        debug("%s: %s", name, op);
 451                } else {
 452                        warn("%s: %s", name, op);
 453                        break;
 454                }
 455        }
 456
 457        pthread_cleanup_pop(1);
 458
 459        t->status = ret;
 460        info("%s: ends\n", t->filename);
 461        return NULL;
 462}
 463
 464static void start_thread(struct thread *t)
 465{
 466        debug("%s: starting\n", t->filename);
 467
 468        die_on(pthread_create(&t->id, NULL, start_thread_helper, t) < 0,
 469               "pthread_create(%s)", t->filename);
 470}
 471
 472static void join_thread(struct thread *t)
 473{
 474        int ret = pthread_join(t->id, NULL);
 475
 476        if (ret < 0)
 477                err("%s: joining thread", t->filename);
 478        else
 479                debug("%s: joined\n", t->filename);
 480}
 481
 482
 483static ssize_t read_wrap(struct thread *t, void *buf, size_t nbytes)
 484{
 485        return read(t->fd, buf, nbytes);
 486}
 487
 488static ssize_t write_wrap(struct thread *t, const void *buf, size_t nbytes)
 489{
 490        return write(t->fd, buf, nbytes);
 491}
 492
 493
 494/******************** Empty/Fill buffer routines ****************************/
 495
 496/* 0 -- stream of zeros, 1 -- i % 63, 2 -- pipe */
 497enum pattern { PAT_ZERO, PAT_SEQ, PAT_PIPE };
 498static enum pattern pattern;
 499
 500static ssize_t
 501fill_in_buf(struct thread *ignore, void *buf, size_t nbytes)
 502{
 503        size_t i;
 504        __u8 *p;
 505
 506        (void)ignore;
 507
 508        switch (pattern) {
 509        case PAT_ZERO:
 510                memset(buf, 0, nbytes);
 511                break;
 512
 513        case PAT_SEQ:
 514                for (p = buf, i = 0; i < nbytes; ++i, ++p)
 515                        *p = i % 63;
 516                break;
 517
 518        case PAT_PIPE:
 519                return fread(buf, 1, nbytes, stdin);
 520        }
 521
 522        return nbytes;
 523}
 524
 525static ssize_t
 526empty_out_buf(struct thread *ignore, const void *buf, size_t nbytes)
 527{
 528        const __u8 *p;
 529        __u8 expected;
 530        ssize_t ret;
 531        size_t len;
 532
 533        (void)ignore;
 534
 535        switch (pattern) {
 536        case PAT_ZERO:
 537                expected = 0;
 538                for (p = buf, len = 0; len < nbytes; ++p, ++len)
 539                        if (*p)
 540                                goto invalid;
 541                break;
 542
 543        case PAT_SEQ:
 544                for (p = buf, len = 0; len < nbytes; ++p, ++len)
 545                        if (*p != len % 63) {
 546                                expected = len % 63;
 547                                goto invalid;
 548                        }
 549                break;
 550
 551        case PAT_PIPE:
 552                ret = fwrite(buf, nbytes, 1, stdout);
 553                if (ret > 0)
 554                        fflush(stdout);
 555                break;
 556
 557invalid:
 558                err("bad OUT byte %zd, expected %02x got %02x\n",
 559                    len, expected, *p);
 560                for (p = buf, len = 0; len < nbytes; ++p, ++len) {
 561                        if (0 == (len % 32))
 562                                fprintf(stderr, "%4zd:", len);
 563                        fprintf(stderr, " %02x", *p);
 564                        if (31 == (len % 32))
 565                                fprintf(stderr, "\n");
 566                }
 567                fflush(stderr);
 568                errno = EILSEQ;
 569                return -1;
 570        }
 571
 572        return len;
 573}
 574
 575
 576/******************** Endpoints routines ************************************/
 577
 578static void handle_setup(const struct usb_ctrlrequest *setup)
 579{
 580        printf("bRequestType = %d\n", setup->bRequestType);
 581        printf("bRequest     = %d\n", setup->bRequest);
 582        printf("wValue       = %d\n", le16_to_cpu(setup->wValue));
 583        printf("wIndex       = %d\n", le16_to_cpu(setup->wIndex));
 584        printf("wLength      = %d\n", le16_to_cpu(setup->wLength));
 585}
 586
 587static ssize_t
 588ep0_consume(struct thread *ignore, const void *buf, size_t nbytes)
 589{
 590        static const char *const names[] = {
 591                [FUNCTIONFS_BIND] = "BIND",
 592                [FUNCTIONFS_UNBIND] = "UNBIND",
 593                [FUNCTIONFS_ENABLE] = "ENABLE",
 594                [FUNCTIONFS_DISABLE] = "DISABLE",
 595                [FUNCTIONFS_SETUP] = "SETUP",
 596                [FUNCTIONFS_SUSPEND] = "SUSPEND",
 597                [FUNCTIONFS_RESUME] = "RESUME",
 598        };
 599
 600        const struct usb_functionfs_event *event = buf;
 601        size_t n;
 602
 603        (void)ignore;
 604
 605        for (n = nbytes / sizeof *event; n; --n, ++event)
 606                switch (event->type) {
 607                case FUNCTIONFS_BIND:
 608                case FUNCTIONFS_UNBIND:
 609                case FUNCTIONFS_ENABLE:
 610                case FUNCTIONFS_DISABLE:
 611                case FUNCTIONFS_SETUP:
 612                case FUNCTIONFS_SUSPEND:
 613                case FUNCTIONFS_RESUME:
 614                        printf("Event %s\n", names[event->type]);
 615                        if (event->type == FUNCTIONFS_SETUP)
 616                                handle_setup(&event->u.setup);
 617                        break;
 618
 619                default:
 620                        printf("Event %03u (unknown)\n", event->type);
 621                }
 622
 623        return nbytes;
 624}
 625
 626static void ep0_init(struct thread *t, bool legacy_descriptors)
 627{
 628        void *legacy;
 629        ssize_t ret;
 630        size_t len;
 631
 632        if (legacy_descriptors) {
 633                info("%s: writing descriptors\n", t->filename);
 634                goto legacy;
 635        }
 636
 637        info("%s: writing descriptors (in v2 format)\n", t->filename);
 638        ret = write(t->fd, &descriptors, sizeof descriptors);
 639
 640        if (ret < 0 && errno == EINVAL) {
 641                warn("%s: new format rejected, trying legacy\n", t->filename);
 642legacy:
 643                len = descs_to_legacy(&legacy, &descriptors);
 644                if (len) {
 645                        ret = write(t->fd, legacy, len);
 646                        free(legacy);
 647                }
 648        }
 649        die_on(ret < 0, "%s: write: descriptors", t->filename);
 650
 651        info("%s: writing strings\n", t->filename);
 652        ret = write(t->fd, &strings, sizeof strings);
 653        die_on(ret < 0, "%s: write: strings", t->filename);
 654}
 655
 656
 657/******************** Main **************************************************/
 658
 659int main(int argc, char **argv)
 660{
 661        bool legacy_descriptors;
 662        unsigned i;
 663
 664        legacy_descriptors = argc > 2 && !strcmp(argv[1], "-l");
 665
 666        init_thread(threads);
 667        ep0_init(threads, legacy_descriptors);
 668
 669        for (i = 1; i < sizeof threads / sizeof *threads; ++i)
 670                init_thread(threads + i);
 671
 672        for (i = 1; i < sizeof threads / sizeof *threads; ++i)
 673                start_thread(threads + i);
 674
 675        start_thread_helper(threads);
 676
 677        for (i = 1; i < sizeof threads / sizeof *threads; ++i)
 678                join_thread(threads + i);
 679
 680        return 0;
 681}
 682