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 #ifndef SHELL_PATH
   8 # define SHELL_PATH "/bin/sh"
   9 #endif
  10
  11 struct child_to_clean {
  12         pid_t pid;
  13         struct child_to_clean *next;
  14 };
  15 static struct child_to_clean *children_to_clean;
  16 static int installed_child_cleanup_handler;
  17
  18 static void cleanup_children(int sig)
  19 {
  20         while (children_to_clean) {
  21                 struct child_to_clean *p = children_to_clean;
  22                 children_to_clean = p->next;
  23                 kill(p->pid, sig);
  24                 free(p);
  25         }
  26 }
  27
  28 static void cleanup_children_on_signal(int sig)
  29 {
  30         cleanup_children(sig);
  31         sigchain_pop(sig);
  32         raise(sig);
  33 }
  34
  35 static void cleanup_children_on_exit(void)
  36 {
  37         cleanup_children(SIGTERM);
  38 }
  39
  40 static void mark_child_for_cleanup(pid_t pid)
  41 {
  42         struct child_to_clean *p = xmalloc(sizeof(*p));
  43         p->pid = pid;
  44         p->next = children_to_clean;
  45         children_to_clean = p;
  46
  47         if (!installed_child_cleanup_handler) {
  48                 atexit(cleanup_children_on_exit);
  49                 sigchain_push_common(cleanup_children_on_signal);
  50                 installed_child_cleanup_handler = 1;
  51         }
  52 }
  53
  54 static void clear_child_for_cleanup(pid_t pid)
  55 {
  56         struct child_to_clean **pp;
  57
  58         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
  59                 struct child_to_clean *clean_me = *pp;
  60
  61                 if (clean_me->pid == pid) {
  62                         *pp = clean_me->next;
  63                         free(clean_me);
  64                         return;
  65                 }
  66         }
  67 }
  68
  69 static inline void close_pair(int fd[2])
  70 {
  71         close(fd[0]);
  72         close(fd[1]);
  73 }
  74
  75 #ifndef GIT_WINDOWS_NATIVE
  76 static inline void dup_devnull(int to)
  77 {
  78         int fd = open("/dev/null", O_RDWR);
  79         if (fd < 0)
  80                 die_errno(_("open /dev/null failed"));
  81         if (dup2(fd, to) < 0)
  82                 die_errno(_("dup2(%d,%d) failed"), fd, to);
  83         close(fd);
  84 }
  85 #endif
  86
  87 static char *locate_in_PATH(const char *file)
  88 {
  89         const char *p = getenv("PATH");
  90         struct strbuf buf = STRBUF_INIT;
  91
  92         if (!p || !*p)
  93                 return NULL;
  94
  95         while (1) {
  96                 const char *end = strchrnul(p, ':');
  97
  98                 strbuf_reset(&buf);
  99
 100                 /* POSIX specifies an empty entry as the current directory. */
 101                 if (end != p) {
 102                         strbuf_add(&buf, p, end - p);
 103                         strbuf_addch(&buf, '/');
 104                 }
 105                 strbuf_addstr(&buf, file);
 106
 107                 if (!access(buf.buf, F_OK))
 108                         return strbuf_detach(&buf, NULL);
 109
 110                 if (!*end)
 111                         break;
 112                 p = end + 1;
 113         }
 114
 115         strbuf_release(&buf);
 116         return NULL;
 117 }
 118
 119 static int exists_in_PATH(const char *file)
 120 {
 121         char *r = locate_in_PATH(file);
 122         free(r);
 123         return r != NULL;
 124 }
 125
 126 int sane_execvp(const char *file, char * const argv[])
 127 {
 128         if (!execvp(file, argv))
 129                 return 0; /* cannot happen ;-) */
 130
 131         /*
 132          * When a command can't be found because one of the directories
 133          * listed in $PATH is unsearchable, execvp reports EACCES, but
 134          * careful usability testing (read: analysis of occasional bug
 135          * reports) reveals that "No such file or directory" is more
 136          * intuitive.
 137          *
 138          * We avoid commands with "/", because execvp will not do $PATH
 139          * lookups in that case.
 140          *
 141          * The reassignment of EACCES to errno looks like a no-op below,
 142          * but we need to protect against exists_in_PATH overwriting errno.
 143          */
 144         if (errno == EACCES && !strchr(file, '/'))
 145                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 146         else if (errno == ENOTDIR && !strchr(file, '/'))
 147                 errno = ENOENT;
 148         return -1;
 149 }
 150
 151 static const char **prepare_shell_cmd(const char **argv)
 152 {
 153         int argc, nargc = 0;
 154         const char **nargv;
 155
 156         for (argc = 0; argv[argc]; argc++)
 157                 ; /* just counting */
 158         /* +1 for NULL, +3 for "sh -c" plus extra $0 */
 159         nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
 160
 161         if (argc < 1)
 162                 die("BUG: shell command is empty");
 163
 164         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 165 #ifndef GIT_WINDOWS_NATIVE
 166                 nargv[nargc++] = SHELL_PATH;
 167 #else
 168                 nargv[nargc++] = "sh";
 169 #endif
 170                 nargv[nargc++] = "-c";
 171
 172                 if (argc < 2)
 173                         nargv[nargc++] = argv[0];
 174                 else {
 175                         struct strbuf arg0 = STRBUF_INIT;
 176                         strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
 177                         nargv[nargc++] = strbuf_detach(&arg0, NULL);
 178                 }
 179         }
 180
 181         for (argc = 0; argv[argc]; argc++)
 182                 nargv[nargc++] = argv[argc];
 183         nargv[nargc] = NULL;
 184
 185         return nargv;
 186 }
 187
 188 #ifndef GIT_WINDOWS_NATIVE
 189 static int execv_shell_cmd(const char **argv)
 190 {
 191         const char **nargv = prepare_shell_cmd(argv);
 192         trace_argv_printf(nargv, "trace: exec:");
 193         sane_execvp(nargv[0], (char **)nargv);
 194         free(nargv);
 195         return -1;
 196 }
 197 #endif
 198
 199 #ifndef GIT_WINDOWS_NATIVE
 200 static int child_err = 2;
 201 static int child_notifier = -1;
 202
 203 static void notify_parent(void)
 204 {
 205         /*
 206          * execvp failed.  If possible, we'd like to let start_command
 207          * know, so failures like ENOENT can be handled right away; but
 208          * otherwise, finish_command will still report the error.
 209          */
 210         xwrite(child_notifier, "", 1);
 211 }
 212
 213 static NORETURN void die_child(const char *err, va_list params)
 214 {
 215         vwritef(child_err, "fatal: ", err, params);
 216         exit(128);
 217 }
 218
 219 static void error_child(const char *err, va_list params)
 220 {
 221         vwritef(child_err, "error: ", err, params);
 222 }
 223 #endif
 224
 225 static inline void set_cloexec(int fd)
 226 {
 227         int flags = fcntl(fd, F_GETFD);
 228         if (flags >= 0)
 229                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 230 }
 231
 232 static int wait_or_whine(pid_t pid, const char *argv0)
 233 {
 234         int status, code = -1;
 235         pid_t waiting;
 236         int failed_errno = 0;
 237
 238         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 239                 ;       /* nothing */
 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         /*
 283          * In case of errors we must keep the promise to close FDs
 284          * that have been passed in via ->in and ->out.
 285          */
 286
 287         need_in = !cmd->no_stdin && cmd->in < 0;
 288         if (need_in) {
 289                 if (pipe(fdin) < 0) {
 290                         failed_errno = errno;
 291                         if (cmd->out > 0)
 292                                 close(cmd->out);
 293                         str = "standard input";
 294                         goto fail_pipe;
 295                 }
 296                 cmd->in = fdin[1];
 297         }
 298
 299         need_out = !cmd->no_stdout
 300                 && !cmd->stdout_to_stderr
 301                 && cmd->out < 0;
 302         if (need_out) {
 303                 if (pipe(fdout) < 0) {
 304                         failed_errno = errno;
 305                         if (need_in)
 306                                 close_pair(fdin);
 307                         else if (cmd->in)
 308                                 close(cmd->in);
 309                         str = "standard output";
 310                         goto fail_pipe;
 311                 }
 312                 cmd->out = fdout[0];
 313         }
 314
 315         need_err = !cmd->no_stderr && cmd->err < 0;
 316         if (need_err) {
 317                 if (pipe(fderr) < 0) {
 318                         failed_errno = errno;
 319                         if (need_in)
 320                                 close_pair(fdin);
 321                         else if (cmd->in)
 322                                 close(cmd->in);
 323                         if (need_out)
 324                                 close_pair(fdout);
 325                         else if (cmd->out)
 326                                 close(cmd->out);
 327                         str = "standard error";
 328 fail_pipe:
 329                         error("cannot create %s pipe for %s: %s",
 330                                 str, cmd->argv[0], strerror(failed_errno));
 331                         errno = failed_errno;
 332                         return -1;
 333                 }
 334                 cmd->err = fderr[0];
 335         }
 336
 337         trace_argv_printf(cmd->argv, "trace: run_command:");
 338         fflush(NULL);
 339
 340 #ifndef GIT_WINDOWS_NATIVE
 341 {
 342         int notify_pipe[2];
 343         if (pipe(notify_pipe))
 344                 notify_pipe[0] = notify_pipe[1] = -1;
 345
 346         cmd->pid = fork();
 347         failed_errno = errno;
 348         if (!cmd->pid) {
 349                 /*
 350                  * Redirect the channel to write syscall error messages to
 351                  * before redirecting the process's stderr so that all die()
 352                  * in subsequent call paths use the parent's stderr.
 353                  */
 354                 if (cmd->no_stderr || need_err) {
 355                         child_err = dup(2);
 356                         set_cloexec(child_err);
 357                 }
 358                 set_die_routine(die_child);
 359                 set_error_routine(error_child);
 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]);
 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                 errno = failed_errno;
 517                 return -1;
 518         }
 519
 520         if (need_in)
 521                 close(fdin[0]);
 522         else if (cmd->in)
 523                 close(cmd->in);
 524
 525         if (need_out)
 526                 close(fdout[1]);
 527         else if (cmd->out)
 528                 close(cmd->out);
 529
 530         if (need_err)
 531                 close(fderr[1]);
 532         else if (cmd->err)
 533                 close(cmd->err);
 534
 535         return 0;
 536 }
 537
 538 int finish_command(struct child_process *cmd)
 539 {
 540         return wait_or_whine(cmd->pid, cmd->argv[0]);
 541 }
 542
 543 int run_command(struct child_process *cmd)
 544 {
 545         int code = start_command(cmd);
 546         if (code)
 547                 return code;
 548         return finish_command(cmd);
 549 }
 550
 551 static void prepare_run_command_v_opt(struct child_process *cmd,
 552                                       const char **argv,
 553                                       int opt)
 554 {
 555         memset(cmd, 0, sizeof(*cmd));
 556         cmd->argv = argv;
 557         cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 558         cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 559         cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 560         cmd->silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 561         cmd->use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 562         cmd->clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 563 }
 564
 565 int run_command_v_opt(const char **argv, int opt)
 566 {
 567         struct child_process cmd;
 568         prepare_run_command_v_opt(&cmd, argv, opt);
 569         return run_command(&cmd);
 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;
 575         prepare_run_command_v_opt(&cmd, argv, opt);
 576         cmd.dir = dir;
 577         cmd.env = env;
 578         return run_command(&cmd);
 579 }
 580
 581 #ifndef NO_PTHREADS
 582 static pthread_t main_thread;
 583 static int main_thread_set;
 584 static pthread_key_t async_key;
 585 static pthread_key_t async_die_counter;
 586
 587 static void *run_thread(void *data)
 588 {
 589         struct async *async = data;
 590         intptr_t ret;
 591
 592         pthread_setspecific(async_key, async);
 593         ret = async->proc(async->proc_in, async->proc_out, async->data);
 594         return (void *)ret;
 595 }
 596
 597 static NORETURN void die_async(const char *err, va_list params)
 598 {
 599         vreportf("fatal: ", err, params);
 600
 601         if (!pthread_equal(main_thread, pthread_self())) {
 602                 struct async *async = pthread_getspecific(async_key);
 603                 if (async->proc_in >= 0)
 604                         close(async->proc_in);
 605                 if (async->proc_out >= 0)
 606                         close(async->proc_out);
 607                 pthread_exit((void *)128);
 608         }
 609
 610         exit(128);
 611 }
 612
 613 static int async_die_is_recursing(void)
 614 {
 615         void *ret = pthread_getspecific(async_die_counter);
 616         pthread_setspecific(async_die_counter, (void *)1);
 617         return ret != NULL;
 618 }
 619
 620 #endif
 621
 622 int start_async(struct async *async)
 623 {
 624         int need_in, need_out;
 625         int fdin[2], fdout[2];
 626         int proc_in, proc_out;
 627
 628         need_in = async->in < 0;
 629         if (need_in) {
 630                 if (pipe(fdin) < 0) {
 631                         if (async->out > 0)
 632                                 close(async->out);
 633                         return error("cannot create pipe: %s", strerror(errno));
 634                 }
 635                 async->in = fdin[1];
 636         }
 637
 638         need_out = async->out < 0;
 639         if (need_out) {
 640                 if (pipe(fdout) < 0) {
 641                         if (need_in)
 642                                 close_pair(fdin);
 643                         else if (async->in)
 644                                 close(async->in);
 645                         return error("cannot create pipe: %s", strerror(errno));
 646                 }
 647                 async->out = fdout[0];
 648         }
 649
 650         if (need_in)
 651                 proc_in = fdin[0];
 652         else if (async->in)
 653                 proc_in = async->in;
 654         else
 655                 proc_in = -1;
 656
 657         if (need_out)
 658                 proc_out = fdout[1];
 659         else if (async->out)
 660                 proc_out = async->out;
 661         else
 662                 proc_out = -1;
 663
 664 #ifdef NO_PTHREADS
 665         /* Flush stdio before fork() to avoid cloning buffers */
 666         fflush(NULL);
 667
 668         async->pid = fork();
 669         if (async->pid < 0) {
 670                 error("fork (async) failed: %s", strerror(errno));
 671                 goto error;
 672         }
 673         if (!async->pid) {
 674                 if (need_in)
 675                         close(fdin[1]);
 676                 if (need_out)
 677                         close(fdout[0]);
 678                 exit(!!async->proc(proc_in, proc_out, async->data));
 679         }
 680
 681         mark_child_for_cleanup(async->pid);
 682
 683         if (need_in)
 684                 close(fdin[0]);
 685         else if (async->in)
 686                 close(async->in);
 687
 688         if (need_out)
 689                 close(fdout[1]);
 690         else if (async->out)
 691                 close(async->out);
 692 #else
 693         if (!main_thread_set) {
 694                 /*
 695                  * We assume that the first time that start_async is called
 696                  * it is from the main thread.
 697                  */
 698                 main_thread_set = 1;
 699                 main_thread = pthread_self();
 700                 pthread_key_create(&async_key, NULL);
 701                 pthread_key_create(&async_die_counter, NULL);
 702                 set_die_routine(die_async);
 703                 set_die_is_recursing_routine(async_die_is_recursing);
 704         }
 705
 706         if (proc_in >= 0)
 707                 set_cloexec(proc_in);
 708         if (proc_out >= 0)
 709                 set_cloexec(proc_out);
 710         async->proc_in = proc_in;
 711         async->proc_out = proc_out;
 712         {
 713                 int err = pthread_create(&async->tid, NULL, run_thread, async);
 714                 if (err) {
 715                         error("cannot create thread: %s", strerror(err));
 716                         goto error;
 717                 }
 718         }
 719 #endif
 720         return 0;
 721
 722 error:
 723         if (need_in)
 724                 close_pair(fdin);
 725         else if (async->in)
 726                 close(async->in);
 727
 728         if (need_out)
 729                 close_pair(fdout);
 730         else if (async->out)
 731                 close(async->out);
 732         return -1;
 733 }
 734
 735 int finish_async(struct async *async)
 736 {
 737 #ifdef NO_PTHREADS
 738         return wait_or_whine(async->pid, "child process");
 739 #else
 740         void *ret = (void *)(intptr_t)(-1);
 741
 742         if (pthread_join(async->tid, &ret))
 743                 error("pthread_join failed");
 744         return (int)(intptr_t)ret;
 745 #endif
 746 }
 747
 748 char *find_hook(const char *name)
 749 {
 750         char *path = git_path("hooks/%s", name);
 751         if (access(path, X_OK) < 0)
 752                 path = NULL;
 753
 754         return path;
 755 }
 756
 757 int run_hook(const char *index_file, const char *name, ...)
 758 {
 759         struct child_process hook;
 760         struct argv_array argv = ARGV_ARRAY_INIT;
 761         const char *p, *env[2];
 762         char index[PATH_MAX];
 763         va_list args;
 764         int ret;
 765
 766         p = find_hook(name);
 767         if (!p)
 768                 return 0;
 769
 770         argv_array_push(&argv, p);
 771
 772         va_start(args, name);
 773         while ((p = va_arg(args, const char *)))
 774                 argv_array_push(&argv, p);
 775         va_end(args);
 776
 777         memset(&hook, 0, sizeof(hook));
 778         hook.argv = argv.argv;
 779         hook.no_stdin = 1;
 780         hook.stdout_to_stderr = 1;
 781         if (index_file) {
 782                 snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
 783                 env[0] = index;
 784                 env[1] = NULL;
 785                 hook.env = env;
 786         }
 787
 788         ret = run_command(&hook);
 789         argv_array_clear(&argv);
 790         return ret;
 791 }