run-command.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "exec_cmd.h"
   4 #include "sigchain.h"
   5 #include "argv-array.h"
   6
   7 void 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
  14 void child_process_clear(struct child_process *child)
  15 {
  16         argv_array_clear(&child->args);
  17         argv_array_clear(&child->env_array);
  18 }
  19
  20 struct child_to_clean {
  21         pid_t pid;
  22         struct child_to_clean *next;
  23 };
  24 static struct child_to_clean *children_to_clean;
  25 static int installed_child_cleanup_handler;
  26
  27 static 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
  38 static void cleanup_children_on_signal(int sig)
  39 {
  40         cleanup_children(sig, 1);
  41         sigchain_pop(sig);
  42         raise(sig);
  43 }
  44
  45 static void cleanup_children_on_exit(void)
  46 {
  47         cleanup_children(SIGTERM, 0);
  48 }
  49
  50 static 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
  64 static 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
  79 static inline void close_pair(int fd[2])
  80 {
  81         close(fd[0]);
  82         close(fd[1]);
  83 }
  84
  85 #ifndef GIT_WINDOWS_NATIVE
  86 static 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
  97 static 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
 129 static int exists_in_PATH(const char *file)
 130 {
 131         char *r = locate_in_PATH(file);
 132         free(r);
 133         return r != NULL;
 134 }
 135
 136 int 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
 161 static 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
 199 static 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
 210 static int child_notifier = -1;
 211
 212 static 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
 223 static 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
 230 static 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
 275 int 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";
 333 fail_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
 544 int 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
 551 int finish_command_in_signal(struct child_process *cmd)
 552 {
 553         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 554 }
 555
 556
 557 int 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
 570 int run_command_v_opt(const char **argv, int opt)
 571 {
 572         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 573 }
 574
 575 int 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
 591 static pthread_t main_thread;
 592 static int main_thread_set;
 593 static pthread_key_t async_key;
 594 static pthread_key_t async_die_counter;
 595
 596 static 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
 606 static NORETURN void die_async(const char *err, va_list params)
 607 {
 608         vreportf("fatal: ", err, params);
 609
 610         if (!pthread_equal(main_thread, pthread_self())) {
 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
 622 static 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
 629 #else
 630
 631 static struct {
 632         void (**handlers)(void);
 633         size_t nr;
 634         size_t alloc;
 635 } git_atexit_hdlrs;
 636
 637 static int git_atexit_installed;
 638
 639 static void git_atexit_dispatch(void)
 640 {
 641         size_t i;
 642
 643         for (i=git_atexit_hdlrs.nr ; i ; i--)
 644                 git_atexit_hdlrs.handlers[i-1]();
 645 }
 646
 647 static void git_atexit_clear(void)
 648 {
 649         free(git_atexit_hdlrs.handlers);
 650         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 651         git_atexit_installed = 0;
 652 }
 653
 654 #undef atexit
 655 int git_atexit(void (*handler)(void))
 656 {
 657         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 658         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 659         if (!git_atexit_installed) {
 660                 if (atexit(&git_atexit_dispatch))
 661                         return -1;
 662                 git_atexit_installed = 1;
 663         }
 664         return 0;
 665 }
 666 #define atexit git_atexit
 667
 668 #endif
 669
 670 int start_async(struct async *async)
 671 {
 672         int need_in, need_out;
 673         int fdin[2], fdout[2];
 674         int proc_in, proc_out;
 675
 676         need_in = async->in < 0;
 677         if (need_in) {
 678                 if (pipe(fdin) < 0) {
 679                         if (async->out > 0)
 680                                 close(async->out);
 681                         return error("cannot create pipe: %s", strerror(errno));
 682                 }
 683                 async->in = fdin[1];
 684         }
 685
 686         need_out = async->out < 0;
 687         if (need_out) {
 688                 if (pipe(fdout) < 0) {
 689                         if (need_in)
 690                                 close_pair(fdin);
 691                         else if (async->in)
 692                                 close(async->in);
 693                         return error("cannot create pipe: %s", strerror(errno));
 694                 }
 695                 async->out = fdout[0];
 696         }
 697
 698         if (need_in)
 699                 proc_in = fdin[0];
 700         else if (async->in)
 701                 proc_in = async->in;
 702         else
 703                 proc_in = -1;
 704
 705         if (need_out)
 706                 proc_out = fdout[1];
 707         else if (async->out)
 708                 proc_out = async->out;
 709         else
 710                 proc_out = -1;
 711
 712 #ifdef NO_PTHREADS
 713         /* Flush stdio before fork() to avoid cloning buffers */
 714         fflush(NULL);
 715
 716         async->pid = fork();
 717         if (async->pid < 0) {
 718                 error("fork (async) failed: %s", strerror(errno));
 719                 goto error;
 720         }
 721         if (!async->pid) {
 722                 if (need_in)
 723                         close(fdin[1]);
 724                 if (need_out)
 725                         close(fdout[0]);
 726                 git_atexit_clear();
 727                 exit(!!async->proc(proc_in, proc_out, async->data));
 728         }
 729
 730         mark_child_for_cleanup(async->pid);
 731
 732         if (need_in)
 733                 close(fdin[0]);
 734         else if (async->in)
 735                 close(async->in);
 736
 737         if (need_out)
 738                 close(fdout[1]);
 739         else if (async->out)
 740                 close(async->out);
 741 #else
 742         if (!main_thread_set) {
 743                 /*
 744                  * We assume that the first time that start_async is called
 745                  * it is from the main thread.
 746                  */
 747                 main_thread_set = 1;
 748                 main_thread = pthread_self();
 749                 pthread_key_create(&async_key, NULL);
 750                 pthread_key_create(&async_die_counter, NULL);
 751                 set_die_routine(die_async);
 752                 set_die_is_recursing_routine(async_die_is_recursing);
 753         }
 754
 755         if (proc_in >= 0)
 756                 set_cloexec(proc_in);
 757         if (proc_out >= 0)
 758                 set_cloexec(proc_out);
 759         async->proc_in = proc_in;
 760         async->proc_out = proc_out;
 761         {
 762                 int err = pthread_create(&async->tid, NULL, run_thread, async);
 763                 if (err) {
 764                         error("cannot create thread: %s", strerror(err));
 765                         goto error;
 766                 }
 767         }
 768 #endif
 769         return 0;
 770
 771 error:
 772         if (need_in)
 773                 close_pair(fdin);
 774         else if (async->in)
 775                 close(async->in);
 776
 777         if (need_out)
 778                 close_pair(fdout);
 779         else if (async->out)
 780                 close(async->out);
 781         return -1;
 782 }
 783
 784 int finish_async(struct async *async)
 785 {
 786 #ifdef NO_PTHREADS
 787         return wait_or_whine(async->pid, "child process", 0);
 788 #else
 789         void *ret = (void *)(intptr_t)(-1);
 790
 791         if (pthread_join(async->tid, &ret))
 792                 error("pthread_join failed");
 793         return (int)(intptr_t)ret;
 794 #endif
 795 }
 796
 797 const char *find_hook(const char *name)
 798 {
 799         static struct strbuf path = STRBUF_INIT;
 800
 801         strbuf_reset(&path);
 802         strbuf_git_path(&path, "hooks/%s", name);
 803         if (access(path.buf, X_OK) < 0)
 804                 return NULL;
 805         return path.buf;
 806 }
 807
 808 int run_hook_ve(const char *const *env, const char *name, va_list args)
 809 {
 810         struct child_process hook = CHILD_PROCESS_INIT;
 811         const char *p;
 812
 813         p = find_hook(name);
 814         if (!p)
 815                 return 0;
 816
 817         argv_array_push(&hook.args, p);
 818         while ((p = va_arg(args, const char *)))
 819                 argv_array_push(&hook.args, p);
 820         hook.env = env;
 821         hook.no_stdin = 1;
 822         hook.stdout_to_stderr = 1;
 823
 824         return run_command(&hook);
 825 }
 826
 827 int run_hook_le(const char *const *env, const char *name, ...)
 828 {
 829         va_list args;
 830         int ret;
 831
 832         va_start(args, name);
 833         ret = run_hook_ve(env, name, args);
 834         va_end(args);
 835
 836         return ret;
 837 }
 838
 839 int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
 840 {
 841         cmd->out = -1;
 842         if (start_command(cmd) < 0)
 843                 return -1;
 844
 845         if (strbuf_read(buf, cmd->out, hint) < 0) {
 846                 close(cmd->out);
 847                 finish_command(cmd); /* throw away exit code */
 848                 return -1;
 849         }
 850
 851         close(cmd->out);
 852         return finish_command(cmd);
 853 }