Andrew's git / gitweb.git / run-command.c
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run-command.con commit Merge branch 'nd/git-common-dir-fix' into maint (9c17cca)
   1#include "cache.h"
   2#include "run-command.h"
   3#include "exec_cmd.h"
   4#include "sigchain.h"
   5#include "argv-array.h"
   6
   7void child_process_init(struct child_process *child)
   8{
   9        memset(child, 0, sizeof(*child));
  10        argv_array_init(&child->args);
  11        argv_array_init(&child->env_array);
  12}
  13
  14void child_process_clear(struct child_process *child)
  15{
  16        argv_array_clear(&child->args);
  17        argv_array_clear(&child->env_array);
  18}
  19
  20struct child_to_clean {
  21        pid_t pid;
  22        struct child_to_clean *next;
  23};
  24static struct child_to_clean *children_to_clean;
  25static int installed_child_cleanup_handler;
  26
  27static void cleanup_children(int sig, int in_signal)
  28{
  29        while (children_to_clean) {
  30                struct child_to_clean *p = children_to_clean;
  31                children_to_clean = p->next;
  32                kill(p->pid, sig);
  33                if (!in_signal)
  34                        free(p);
  35        }
  36}
  37
  38static void cleanup_children_on_signal(int sig)
  39{
  40        cleanup_children(sig, 1);
  41        sigchain_pop(sig);
  42        raise(sig);
  43}
  44
  45static void cleanup_children_on_exit(void)
  46{
  47        cleanup_children(SIGTERM, 0);
  48}
  49
  50static void mark_child_for_cleanup(pid_t pid)
  51{
  52        struct child_to_clean *p = xmalloc(sizeof(*p));
  53        p->pid = pid;
  54        p->next = children_to_clean;
  55        children_to_clean = p;
  56
  57        if (!installed_child_cleanup_handler) {
  58                atexit(cleanup_children_on_exit);
  59                sigchain_push_common(cleanup_children_on_signal);
  60                installed_child_cleanup_handler = 1;
  61        }
  62}
  63
  64static void clear_child_for_cleanup(pid_t pid)
  65{
  66        struct child_to_clean **pp;
  67
  68        for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
  69                struct child_to_clean *clean_me = *pp;
  70
  71                if (clean_me->pid == pid) {
  72                        *pp = clean_me->next;
  73                        free(clean_me);
  74                        return;
  75                }
  76        }
  77}
  78
  79static inline void close_pair(int fd[2])
  80{
  81        close(fd[0]);
  82        close(fd[1]);
  83}
  84
  85#ifndef GIT_WINDOWS_NATIVE
  86static inline void dup_devnull(int to)
  87{
  88        int fd = open("/dev/null", O_RDWR);
  89        if (fd < 0)
  90                die_errno(_("open /dev/null failed"));
  91        if (dup2(fd, to) < 0)
  92                die_errno(_("dup2(%d,%d) failed"), fd, to);
  93        close(fd);
  94}
  95#endif
  96
  97static char *locate_in_PATH(const char *file)
  98{
  99        const char *p = getenv("PATH");
 100        struct strbuf buf = STRBUF_INIT;
 101
 102        if (!p || !*p)
 103                return NULL;
 104
 105        while (1) {
 106                const char *end = strchrnul(p, ':');
 107
 108                strbuf_reset(&buf);
 109
 110                /* POSIX specifies an empty entry as the current directory. */
 111                if (end != p) {
 112                        strbuf_add(&buf, p, end - p);
 113                        strbuf_addch(&buf, '/');
 114                }
 115                strbuf_addstr(&buf, file);
 116
 117                if (!access(buf.buf, F_OK))
 118                        return strbuf_detach(&buf, NULL);
 119
 120                if (!*end)
 121                        break;
 122                p = end + 1;
 123        }
 124
 125        strbuf_release(&buf);
 126        return NULL;
 127}
 128
 129static int exists_in_PATH(const char *file)
 130{
 131        char *r = locate_in_PATH(file);
 132        free(r);
 133        return r != NULL;
 134}
 135
 136int sane_execvp(const char *file, char * const argv[])
 137{
 138        if (!execvp(file, argv))
 139                return 0; /* cannot happen ;-) */
 140
 141        /*
 142         * When a command can't be found because one of the directories
 143         * listed in $PATH is unsearchable, execvp reports EACCES, but
 144         * careful usability testing (read: analysis of occasional bug
 145         * reports) reveals that "No such file or directory" is more
 146         * intuitive.
 147         *
 148         * We avoid commands with "/", because execvp will not do $PATH
 149         * lookups in that case.
 150         *
 151         * The reassignment of EACCES to errno looks like a no-op below,
 152         * but we need to protect against exists_in_PATH overwriting errno.
 153         */
 154        if (errno == EACCES && !strchr(file, '/'))
 155                errno = exists_in_PATH(file) ? EACCES : ENOENT;
 156        else if (errno == ENOTDIR && !strchr(file, '/'))
 157                errno = ENOENT;
 158        return -1;
 159}
 160
 161static const char **prepare_shell_cmd(const char **argv)
 162{
 163        int argc, nargc = 0;
 164        const char **nargv;
 165
 166        for (argc = 0; argv[argc]; argc++)
 167                ; /* just counting */
 168        /* +1 for NULL, +3 for "sh -c" plus extra $0 */
 169        nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
 170
 171        if (argc < 1)
 172                die("BUG: shell command is empty");
 173
 174        if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 175#ifndef GIT_WINDOWS_NATIVE
 176                nargv[nargc++] = SHELL_PATH;
 177#else
 178                nargv[nargc++] = "sh";
 179#endif
 180                nargv[nargc++] = "-c";
 181
 182                if (argc < 2)
 183                        nargv[nargc++] = argv[0];
 184                else {
 185                        struct strbuf arg0 = STRBUF_INIT;
 186                        strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
 187                        nargv[nargc++] = strbuf_detach(&arg0, NULL);
 188                }
 189        }
 190
 191        for (argc = 0; argv[argc]; argc++)
 192                nargv[nargc++] = argv[argc];
 193        nargv[nargc] = NULL;
 194
 195        return nargv;
 196}
 197
 198#ifndef GIT_WINDOWS_NATIVE
 199static int execv_shell_cmd(const char **argv)
 200{
 201        const char **nargv = prepare_shell_cmd(argv);
 202        trace_argv_printf(nargv, "trace: exec:");
 203        sane_execvp(nargv[0], (char **)nargv);
 204        free(nargv);
 205        return -1;
 206}
 207#endif
 208
 209#ifndef GIT_WINDOWS_NATIVE
 210static int child_notifier = -1;
 211
 212static void notify_parent(void)
 213{
 214        /*
 215         * execvp failed.  If possible, we'd like to let start_command
 216         * know, so failures like ENOENT can be handled right away; but
 217         * otherwise, finish_command will still report the error.
 218         */
 219        xwrite(child_notifier, "", 1);
 220}
 221#endif
 222
 223static inline void set_cloexec(int fd)
 224{
 225        int flags = fcntl(fd, F_GETFD);
 226        if (flags >= 0)
 227                fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 228}
 229
 230static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 231{
 232        int status, code = -1;
 233        pid_t waiting;
 234        int failed_errno = 0;
 235
 236        while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 237                ;       /* nothing */
 238        if (in_signal)
 239                return 0;
 240
 241        if (waiting < 0) {
 242                failed_errno = errno;
 243                error("waitpid for %s failed: %s", argv0, strerror(errno));
 244        } else if (waiting != pid) {
 245                error("waitpid is confused (%s)", argv0);
 246        } else if (WIFSIGNALED(status)) {
 247                code = WTERMSIG(status);
 248                if (code != SIGINT && code != SIGQUIT)
 249                        error("%s died of signal %d", argv0, code);
 250                /*
 251                 * This return value is chosen so that code & 0xff
 252                 * mimics the exit code that a POSIX shell would report for
 253                 * a program that died from this signal.
 254                 */
 255                code += 128;
 256        } else if (WIFEXITED(status)) {
 257                code = WEXITSTATUS(status);
 258                /*
 259                 * Convert special exit code when execvp failed.
 260                 */
 261                if (code == 127) {
 262                        code = -1;
 263                        failed_errno = ENOENT;
 264                }
 265        } else {
 266                error("waitpid is confused (%s)", argv0);
 267        }
 268
 269        clear_child_for_cleanup(pid);
 270
 271        errno = failed_errno;
 272        return code;
 273}
 274
 275int start_command(struct child_process *cmd)
 276{
 277        int need_in, need_out, need_err;
 278        int fdin[2], fdout[2], fderr[2];
 279        int failed_errno;
 280        char *str;
 281
 282        if (!cmd->argv)
 283                cmd->argv = cmd->args.argv;
 284        if (!cmd->env)
 285                cmd->env = cmd->env_array.argv;
 286
 287        /*
 288         * In case of errors we must keep the promise to close FDs
 289         * that have been passed in via ->in and ->out.
 290         */
 291
 292        need_in = !cmd->no_stdin && cmd->in < 0;
 293        if (need_in) {
 294                if (pipe(fdin) < 0) {
 295                        failed_errno = errno;
 296                        if (cmd->out > 0)
 297                                close(cmd->out);
 298                        str = "standard input";
 299                        goto fail_pipe;
 300                }
 301                cmd->in = fdin[1];
 302        }
 303
 304        need_out = !cmd->no_stdout
 305                && !cmd->stdout_to_stderr
 306                && cmd->out < 0;
 307        if (need_out) {
 308                if (pipe(fdout) < 0) {
 309                        failed_errno = errno;
 310                        if (need_in)
 311                                close_pair(fdin);
 312                        else if (cmd->in)
 313                                close(cmd->in);
 314                        str = "standard output";
 315                        goto fail_pipe;
 316                }
 317                cmd->out = fdout[0];
 318        }
 319
 320        need_err = !cmd->no_stderr && cmd->err < 0;
 321        if (need_err) {
 322                if (pipe(fderr) < 0) {
 323                        failed_errno = errno;
 324                        if (need_in)
 325                                close_pair(fdin);
 326                        else if (cmd->in)
 327                                close(cmd->in);
 328                        if (need_out)
 329                                close_pair(fdout);
 330                        else if (cmd->out)
 331                                close(cmd->out);
 332                        str = "standard error";
 333fail_pipe:
 334                        error("cannot create %s pipe for %s: %s",
 335                                str, cmd->argv[0], strerror(failed_errno));
 336                        child_process_clear(cmd);
 337                        errno = failed_errno;
 338                        return -1;
 339                }
 340                cmd->err = fderr[0];
 341        }
 342
 343        trace_argv_printf(cmd->argv, "trace: run_command:");
 344        fflush(NULL);
 345
 346#ifndef GIT_WINDOWS_NATIVE
 347{
 348        int notify_pipe[2];
 349        if (pipe(notify_pipe))
 350                notify_pipe[0] = notify_pipe[1] = -1;
 351
 352        cmd->pid = fork();
 353        failed_errno = errno;
 354        if (!cmd->pid) {
 355                /*
 356                 * Redirect the channel to write syscall error messages to
 357                 * before redirecting the process's stderr so that all die()
 358                 * in subsequent call paths use the parent's stderr.
 359                 */
 360                if (cmd->no_stderr || need_err) {
 361                        int child_err = dup(2);
 362                        set_cloexec(child_err);
 363                        set_error_handle(fdopen(child_err, "w"));
 364                }
 365
 366                close(notify_pipe[0]);
 367                set_cloexec(notify_pipe[1]);
 368                child_notifier = notify_pipe[1];
 369                atexit(notify_parent);
 370
 371                if (cmd->no_stdin)
 372                        dup_devnull(0);
 373                else if (need_in) {
 374                        dup2(fdin[0], 0);
 375                        close_pair(fdin);
 376                } else if (cmd->in) {
 377                        dup2(cmd->in, 0);
 378                        close(cmd->in);
 379                }
 380
 381                if (cmd->no_stderr)
 382                        dup_devnull(2);
 383                else if (need_err) {
 384                        dup2(fderr[1], 2);
 385                        close_pair(fderr);
 386                } else if (cmd->err > 1) {
 387                        dup2(cmd->err, 2);
 388                        close(cmd->err);
 389                }
 390
 391                if (cmd->no_stdout)
 392                        dup_devnull(1);
 393                else if (cmd->stdout_to_stderr)
 394                        dup2(2, 1);
 395                else if (need_out) {
 396                        dup2(fdout[1], 1);
 397                        close_pair(fdout);
 398                } else if (cmd->out > 1) {
 399                        dup2(cmd->out, 1);
 400                        close(cmd->out);
 401                }
 402
 403                if (cmd->dir && chdir(cmd->dir))
 404                        die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 405                            cmd->dir);
 406                if (cmd->env) {
 407                        for (; *cmd->env; cmd->env++) {
 408                                if (strchr(*cmd->env, '='))
 409                                        putenv((char *)*cmd->env);
 410                                else
 411                                        unsetenv(*cmd->env);
 412                        }
 413                }
 414                if (cmd->git_cmd)
 415                        execv_git_cmd(cmd->argv);
 416                else if (cmd->use_shell)
 417                        execv_shell_cmd(cmd->argv);
 418                else
 419                        sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
 420                if (errno == ENOENT) {
 421                        if (!cmd->silent_exec_failure)
 422                                error("cannot run %s: %s", cmd->argv[0],
 423                                        strerror(ENOENT));
 424                        exit(127);
 425                } else {
 426                        die_errno("cannot exec '%s'", cmd->argv[0]);
 427                }
 428        }
 429        if (cmd->pid < 0)
 430                error("cannot fork() for %s: %s", cmd->argv[0],
 431                        strerror(errno));
 432        else if (cmd->clean_on_exit)
 433                mark_child_for_cleanup(cmd->pid);
 434
 435        /*
 436         * Wait for child's execvp. If the execvp succeeds (or if fork()
 437         * failed), EOF is seen immediately by the parent. Otherwise, the
 438         * child process sends a single byte.
 439         * Note that use of this infrastructure is completely advisory,
 440         * therefore, we keep error checks minimal.
 441         */
 442        close(notify_pipe[1]);
 443        if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 444                /*
 445                 * At this point we know that fork() succeeded, but execvp()
 446                 * failed. Errors have been reported to our stderr.
 447                 */
 448                wait_or_whine(cmd->pid, cmd->argv[0], 0);
 449                failed_errno = errno;
 450                cmd->pid = -1;
 451        }
 452        close(notify_pipe[0]);
 453}
 454#else
 455{
 456        int fhin = 0, fhout = 1, fherr = 2;
 457        const char **sargv = cmd->argv;
 458
 459        if (cmd->no_stdin)
 460                fhin = open("/dev/null", O_RDWR);
 461        else if (need_in)
 462                fhin = dup(fdin[0]);
 463        else if (cmd->in)
 464                fhin = dup(cmd->in);
 465
 466        if (cmd->no_stderr)
 467                fherr = open("/dev/null", O_RDWR);
 468        else if (need_err)
 469                fherr = dup(fderr[1]);
 470        else if (cmd->err > 2)
 471                fherr = dup(cmd->err);
 472
 473        if (cmd->no_stdout)
 474                fhout = open("/dev/null", O_RDWR);
 475        else if (cmd->stdout_to_stderr)
 476                fhout = dup(fherr);
 477        else if (need_out)
 478                fhout = dup(fdout[1]);
 479        else if (cmd->out > 1)
 480                fhout = dup(cmd->out);
 481
 482        if (cmd->git_cmd)
 483                cmd->argv = prepare_git_cmd(cmd->argv);
 484        else if (cmd->use_shell)
 485                cmd->argv = prepare_shell_cmd(cmd->argv);
 486
 487        cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 488                        cmd->dir, fhin, fhout, fherr);
 489        failed_errno = errno;
 490        if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 491                error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
 492        if (cmd->clean_on_exit && cmd->pid >= 0)
 493                mark_child_for_cleanup(cmd->pid);
 494
 495        if (cmd->git_cmd)
 496                free(cmd->argv);
 497
 498        cmd->argv = sargv;
 499        if (fhin != 0)
 500                close(fhin);
 501        if (fhout != 1)
 502                close(fhout);
 503        if (fherr != 2)
 504                close(fherr);
 505}
 506#endif
 507
 508        if (cmd->pid < 0) {
 509                if (need_in)
 510                        close_pair(fdin);
 511                else if (cmd->in)
 512                        close(cmd->in);
 513                if (need_out)
 514                        close_pair(fdout);
 515                else if (cmd->out)
 516                        close(cmd->out);
 517                if (need_err)
 518                        close_pair(fderr);
 519                else if (cmd->err)
 520                        close(cmd->err);
 521                child_process_clear(cmd);
 522                errno = failed_errno;
 523                return -1;
 524        }
 525
 526        if (need_in)
 527                close(fdin[0]);
 528        else if (cmd->in)
 529                close(cmd->in);
 530
 531        if (need_out)
 532                close(fdout[1]);
 533        else if (cmd->out)
 534                close(cmd->out);
 535
 536        if (need_err)
 537                close(fderr[1]);
 538        else if (cmd->err)
 539                close(cmd->err);
 540
 541        return 0;
 542}
 543
 544int finish_command(struct child_process *cmd)
 545{
 546        int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 547        child_process_clear(cmd);
 548        return ret;
 549}
 550
 551int finish_command_in_signal(struct child_process *cmd)
 552{
 553        return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 554}
 555
 556
 557int run_command(struct child_process *cmd)
 558{
 559        int code;
 560
 561        if (cmd->out < 0 || cmd->err < 0)
 562                die("BUG: run_command with a pipe can cause deadlock");
 563
 564        code = start_command(cmd);
 565        if (code)
 566                return code;
 567        return finish_command(cmd);
 568}
 569
 570int run_command_v_opt(const char **argv, int opt)
 571{
 572        return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 573}
 574
 575int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 576{
 577        struct child_process cmd = CHILD_PROCESS_INIT;
 578        cmd.argv = argv;
 579        cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 580        cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 581        cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 582        cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 583        cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 584        cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 585        cmd.dir = dir;
 586        cmd.env = env;
 587        return run_command(&cmd);
 588}
 589
 590#ifndef NO_PTHREADS
 591static pthread_t main_thread;
 592static int main_thread_set;
 593static pthread_key_t async_key;
 594static pthread_key_t async_die_counter;
 595
 596static void *run_thread(void *data)
 597{
 598        struct async *async = data;
 599        intptr_t ret;
 600
 601        pthread_setspecific(async_key, async);
 602        ret = async->proc(async->proc_in, async->proc_out, async->data);
 603        return (void *)ret;
 604}
 605
 606static NORETURN void die_async(const char *err, va_list params)
 607{
 608        vreportf("fatal: ", err, params);
 609
 610        if (in_async()) {
 611                struct async *async = pthread_getspecific(async_key);
 612                if (async->proc_in >= 0)
 613                        close(async->proc_in);
 614                if (async->proc_out >= 0)
 615                        close(async->proc_out);
 616                pthread_exit((void *)128);
 617        }
 618
 619        exit(128);
 620}
 621
 622static int async_die_is_recursing(void)
 623{
 624        void *ret = pthread_getspecific(async_die_counter);
 625        pthread_setspecific(async_die_counter, (void *)1);
 626        return ret != NULL;
 627}
 628
 629int in_async(void)
 630{
 631        if (!main_thread_set)
 632                return 0; /* no asyncs started yet */
 633        return !pthread_equal(main_thread, pthread_self());
 634}
 635
 636void NORETURN async_exit(int code)
 637{
 638        pthread_exit((void *)(intptr_t)code);
 639}
 640
 641#else
 642
 643static struct {
 644        void (**handlers)(void);
 645        size_t nr;
 646        size_t alloc;
 647} git_atexit_hdlrs;
 648
 649static int git_atexit_installed;
 650
 651static void git_atexit_dispatch(void)
 652{
 653        size_t i;
 654
 655        for (i=git_atexit_hdlrs.nr ; i ; i--)
 656                git_atexit_hdlrs.handlers[i-1]();
 657}
 658
 659static void git_atexit_clear(void)
 660{
 661        free(git_atexit_hdlrs.handlers);
 662        memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 663        git_atexit_installed = 0;
 664}
 665
 666#undef atexit
 667int git_atexit(void (*handler)(void))
 668{
 669        ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 670        git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 671        if (!git_atexit_installed) {
 672                if (atexit(&git_atexit_dispatch))
 673                        return -1;
 674                git_atexit_installed = 1;
 675        }
 676        return 0;
 677}
 678#define atexit git_atexit
 679
 680static int process_is_async;
 681int in_async(void)
 682{
 683        return process_is_async;
 684}
 685
 686void NORETURN async_exit(int code)
 687{
 688        exit(code);
 689}
 690
 691#endif
 692
 693int start_async(struct async *async)
 694{
 695        int need_in, need_out;
 696        int fdin[2], fdout[2];
 697        int proc_in, proc_out;
 698
 699        need_in = async->in < 0;
 700        if (need_in) {
 701                if (pipe(fdin) < 0) {
 702                        if (async->out > 0)
 703                                close(async->out);
 704                        return error("cannot create pipe: %s", strerror(errno));
 705                }
 706                async->in = fdin[1];
 707        }
 708
 709        need_out = async->out < 0;
 710        if (need_out) {
 711                if (pipe(fdout) < 0) {
 712                        if (need_in)
 713                                close_pair(fdin);
 714                        else if (async->in)
 715                                close(async->in);
 716                        return error("cannot create pipe: %s", strerror(errno));
 717                }
 718                async->out = fdout[0];
 719        }
 720
 721        if (need_in)
 722                proc_in = fdin[0];
 723        else if (async->in)
 724                proc_in = async->in;
 725        else
 726                proc_in = -1;
 727
 728        if (need_out)
 729                proc_out = fdout[1];
 730        else if (async->out)
 731                proc_out = async->out;
 732        else
 733                proc_out = -1;
 734
 735#ifdef NO_PTHREADS
 736        /* Flush stdio before fork() to avoid cloning buffers */
 737        fflush(NULL);
 738
 739        async->pid = fork();
 740        if (async->pid < 0) {
 741                error("fork (async) failed: %s", strerror(errno));
 742                goto error;
 743        }
 744        if (!async->pid) {
 745                if (need_in)
 746                        close(fdin[1]);
 747                if (need_out)
 748                        close(fdout[0]);
 749                git_atexit_clear();
 750                process_is_async = 1;
 751                exit(!!async->proc(proc_in, proc_out, async->data));
 752        }
 753
 754        mark_child_for_cleanup(async->pid);
 755
 756        if (need_in)
 757                close(fdin[0]);
 758        else if (async->in)
 759                close(async->in);
 760
 761        if (need_out)
 762                close(fdout[1]);
 763        else if (async->out)
 764                close(async->out);
 765#else
 766        if (!main_thread_set) {
 767                /*
 768                 * We assume that the first time that start_async is called
 769                 * it is from the main thread.
 770                 */
 771                main_thread_set = 1;
 772                main_thread = pthread_self();
 773                pthread_key_create(&async_key, NULL);
 774                pthread_key_create(&async_die_counter, NULL);
 775                set_die_routine(die_async);
 776                set_die_is_recursing_routine(async_die_is_recursing);
 777        }
 778
 779        if (proc_in >= 0)
 780                set_cloexec(proc_in);
 781        if (proc_out >= 0)
 782                set_cloexec(proc_out);
 783        async->proc_in = proc_in;
 784        async->proc_out = proc_out;
 785        {
 786                int err = pthread_create(&async->tid, NULL, run_thread, async);
 787                if (err) {
 788                        error("cannot create thread: %s", strerror(err));
 789                        goto error;
 790                }
 791        }
 792#endif
 793        return 0;
 794
 795error:
 796        if (need_in)
 797                close_pair(fdin);
 798        else if (async->in)
 799                close(async->in);
 800
 801        if (need_out)
 802                close_pair(fdout);
 803        else if (async->out)
 804                close(async->out);
 805        return -1;
 806}
 807
 808int finish_async(struct async *async)
 809{
 810#ifdef NO_PTHREADS
 811        return wait_or_whine(async->pid, "child process", 0);
 812#else
 813        void *ret = (void *)(intptr_t)(-1);
 814
 815        if (pthread_join(async->tid, &ret))
 816                error("pthread_join failed");
 817        return (int)(intptr_t)ret;
 818#endif
 819}
 820
 821const char *find_hook(const char *name)
 822{
 823        static struct strbuf path = STRBUF_INIT;
 824
 825        strbuf_reset(&path);
 826        strbuf_git_path(&path, "hooks/%s", name);
 827        if (access(path.buf, X_OK) < 0)
 828                return NULL;
 829        return path.buf;
 830}
 831
 832int run_hook_ve(const char *const *env, const char *name, va_list args)
 833{
 834        struct child_process hook = CHILD_PROCESS_INIT;
 835        const char *p;
 836
 837        p = find_hook(name);
 838        if (!p)
 839                return 0;
 840
 841        argv_array_push(&hook.args, p);
 842        while ((p = va_arg(args, const char *)))
 843                argv_array_push(&hook.args, p);
 844        hook.env = env;
 845        hook.no_stdin = 1;
 846        hook.stdout_to_stderr = 1;
 847
 848        return run_command(&hook);
 849}
 850
 851int run_hook_le(const char *const *env, const char *name, ...)
 852{
 853        va_list args;
 854        int ret;
 855
 856        va_start(args, name);
 857        ret = run_hook_ve(env, name, args);
 858        va_end(args);
 859
 860        return ret;
 861}
 862
 863int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
 864{
 865        cmd->out = -1;
 866        if (start_command(cmd) < 0)
 867                return -1;
 868
 869        if (strbuf_read(buf, cmd->out, hint) < 0) {
 870                close(cmd->out);
 871                finish_command(cmd); /* throw away exit code */
 872                return -1;
 873        }
 874
 875        close(cmd->out);
 876        return finish_command(cmd);
 877}