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