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