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 #include "thread-utils.h"
   7 #include "strbuf.h"
   8
   9 void child_process_init(struct child_process *child)
  10 {
  11         memset(child, 0, sizeof(*child));
  12         argv_array_init(&child->args);
  13         argv_array_init(&child->env_array);
  14 }
  15
  16 void child_process_clear(struct child_process *child)
  17 {
  18         argv_array_clear(&child->args);
  19         argv_array_clear(&child->env_array);
  20 }
  21
  22 struct child_to_clean {
  23         pid_t pid;
  24         struct child_process *process;
  25         struct child_to_clean *next;
  26 };
  27 static struct child_to_clean *children_to_clean;
  28 static int installed_child_cleanup_handler;
  29
  30 static void cleanup_children(int sig, int in_signal)
  31 {
  32         struct child_to_clean *children_to_wait_for = NULL;
  33
  34         while (children_to_clean) {
  35                 struct child_to_clean *p = children_to_clean;
  36                 children_to_clean = p->next;
  37
  38                 if (p->process && !in_signal) {
  39                         struct child_process *process = p->process;
  40                         if (process->clean_on_exit_handler) {
  41                                 trace_printf(
  42                                         "trace: run_command: running exit handler for pid %"
  43                                         PRIuMAX, (uintmax_t)p->pid
  44                                 );
  45                                 process->clean_on_exit_handler(process);
  46                         }
  47                 }
  48
  49                 kill(p->pid, sig);
  50
  51                 if (p->process && p->process->wait_after_clean) {
  52                         p->next = children_to_wait_for;
  53                         children_to_wait_for = p;
  54                 } else {
  55                         if (!in_signal)
  56                                 free(p);
  57                 }
  58         }
  59
  60         while (children_to_wait_for) {
  61                 struct child_to_clean *p = children_to_wait_for;
  62                 children_to_wait_for = p->next;
  63
  64                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  65                         ; /* spin waiting for process exit or error */
  66
  67                 if (!in_signal)
  68                         free(p);
  69         }
  70 }
  71
  72 static void cleanup_children_on_signal(int sig)
  73 {
  74         cleanup_children(sig, 1);
  75         sigchain_pop(sig);
  76         raise(sig);
  77 }
  78
  79 static void cleanup_children_on_exit(void)
  80 {
  81         cleanup_children(SIGTERM, 0);
  82 }
  83
  84 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  85 {
  86         struct child_to_clean *p = xmalloc(sizeof(*p));
  87         p->pid = pid;
  88         p->process = process;
  89         p->next = children_to_clean;
  90         children_to_clean = p;
  91
  92         if (!installed_child_cleanup_handler) {
  93                 atexit(cleanup_children_on_exit);
  94                 sigchain_push_common(cleanup_children_on_signal);
  95                 installed_child_cleanup_handler = 1;
  96         }
  97 }
  98
  99 static void clear_child_for_cleanup(pid_t pid)
 100 {
 101         struct child_to_clean **pp;
 102
 103         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 104                 struct child_to_clean *clean_me = *pp;
 105
 106                 if (clean_me->pid == pid) {
 107                         *pp = clean_me->next;
 108                         free(clean_me);
 109                         return;
 110                 }
 111         }
 112 }
 113
 114 static inline void close_pair(int fd[2])
 115 {
 116         close(fd[0]);
 117         close(fd[1]);
 118 }
 119
 120 #ifndef GIT_WINDOWS_NATIVE
 121 static inline void dup_devnull(int to)
 122 {
 123         int fd = open("/dev/null", O_RDWR);
 124         if (fd < 0)
 125                 die_errno(_("open /dev/null failed"));
 126         if (dup2(fd, to) < 0)
 127                 die_errno(_("dup2(%d,%d) failed"), fd, to);
 128         close(fd);
 129 }
 130 #endif
 131
 132 static char *locate_in_PATH(const char *file)
 133 {
 134         const char *p = getenv("PATH");
 135         struct strbuf buf = STRBUF_INIT;
 136
 137         if (!p || !*p)
 138                 return NULL;
 139
 140         while (1) {
 141                 const char *end = strchrnul(p, ':');
 142
 143                 strbuf_reset(&buf);
 144
 145                 /* POSIX specifies an empty entry as the current directory. */
 146                 if (end != p) {
 147                         strbuf_add(&buf, p, end - p);
 148                         strbuf_addch(&buf, '/');
 149                 }
 150                 strbuf_addstr(&buf, file);
 151
 152                 if (!access(buf.buf, F_OK))
 153                         return strbuf_detach(&buf, NULL);
 154
 155                 if (!*end)
 156                         break;
 157                 p = end + 1;
 158         }
 159
 160         strbuf_release(&buf);
 161         return NULL;
 162 }
 163
 164 static int exists_in_PATH(const char *file)
 165 {
 166         char *r = locate_in_PATH(file);
 167         free(r);
 168         return r != NULL;
 169 }
 170
 171 int sane_execvp(const char *file, char * const argv[])
 172 {
 173         if (!execvp(file, argv))
 174                 return 0; /* cannot happen ;-) */
 175
 176         /*
 177          * When a command can't be found because one of the directories
 178          * listed in $PATH is unsearchable, execvp reports EACCES, but
 179          * careful usability testing (read: analysis of occasional bug
 180          * reports) reveals that "No such file or directory" is more
 181          * intuitive.
 182          *
 183          * We avoid commands with "/", because execvp will not do $PATH
 184          * lookups in that case.
 185          *
 186          * The reassignment of EACCES to errno looks like a no-op below,
 187          * but we need to protect against exists_in_PATH overwriting errno.
 188          */
 189         if (errno == EACCES && !strchr(file, '/'))
 190                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 191         else if (errno == ENOTDIR && !strchr(file, '/'))
 192                 errno = ENOENT;
 193         return -1;
 194 }
 195
 196 static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 197 {
 198         if (!argv[0])
 199                 die("BUG: shell command is empty");
 200
 201         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 202 #ifndef GIT_WINDOWS_NATIVE
 203                 argv_array_push(out, SHELL_PATH);
 204 #else
 205                 argv_array_push(out, "sh");
 206 #endif
 207                 argv_array_push(out, "-c");
 208
 209                 /*
 210                  * If we have no extra arguments, we do not even need to
 211                  * bother with the "$@" magic.
 212                  */
 213                 if (!argv[1])
 214                         argv_array_push(out, argv[0]);
 215                 else
 216                         argv_array_pushf(out, "%s \"$@\"", argv[0]);
 217         }
 218
 219         argv_array_pushv(out, argv);
 220         return out->argv;
 221 }
 222
 223 #ifndef GIT_WINDOWS_NATIVE
 224 static int child_notifier = -1;
 225
 226 static void notify_parent(void)
 227 {
 228         /*
 229          * execvp failed.  If possible, we'd like to let start_command
 230          * know, so failures like ENOENT can be handled right away; but
 231          * otherwise, finish_command will still report the error.
 232          */
 233         xwrite(child_notifier, "", 1);
 234 }
 235
 236 static void prepare_cmd(struct argv_array *out, const struct child_process *cmd)
 237 {
 238         if (!cmd->argv[0])
 239                 die("BUG: command is empty");
 240
 241         if (cmd->git_cmd) {
 242                 argv_array_push(out, "git");
 243                 argv_array_pushv(out, cmd->argv);
 244         } else if (cmd->use_shell) {
 245                 prepare_shell_cmd(out, cmd->argv);
 246         } else {
 247                 argv_array_pushv(out, cmd->argv);
 248         }
 249 }
 250 #endif
 251
 252 static inline void set_cloexec(int fd)
 253 {
 254         int flags = fcntl(fd, F_GETFD);
 255         if (flags >= 0)
 256                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 257 }
 258
 259 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 260 {
 261         int status, code = -1;
 262         pid_t waiting;
 263         int failed_errno = 0;
 264
 265         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 266                 ;       /* nothing */
 267         if (in_signal)
 268                 return 0;
 269
 270         if (waiting < 0) {
 271                 failed_errno = errno;
 272                 error_errno("waitpid for %s failed", argv0);
 273         } else if (waiting != pid) {
 274                 error("waitpid is confused (%s)", argv0);
 275         } else if (WIFSIGNALED(status)) {
 276                 code = WTERMSIG(status);
 277                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 278                         error("%s died of signal %d", argv0, code);
 279                 /*
 280                  * This return value is chosen so that code & 0xff
 281                  * mimics the exit code that a POSIX shell would report for
 282                  * a program that died from this signal.
 283                  */
 284                 code += 128;
 285         } else if (WIFEXITED(status)) {
 286                 code = WEXITSTATUS(status);
 287                 /*
 288                  * Convert special exit code when execvp failed.
 289                  */
 290                 if (code == 127) {
 291                         code = -1;
 292                         failed_errno = ENOENT;
 293                 }
 294         } else {
 295                 error("waitpid is confused (%s)", argv0);
 296         }
 297
 298         clear_child_for_cleanup(pid);
 299
 300         errno = failed_errno;
 301         return code;
 302 }
 303
 304 int start_command(struct child_process *cmd)
 305 {
 306         int need_in, need_out, need_err;
 307         int fdin[2], fdout[2], fderr[2];
 308         int failed_errno;
 309         char *str;
 310
 311         if (!cmd->argv)
 312                 cmd->argv = cmd->args.argv;
 313         if (!cmd->env)
 314                 cmd->env = cmd->env_array.argv;
 315
 316         /*
 317          * In case of errors we must keep the promise to close FDs
 318          * that have been passed in via ->in and ->out.
 319          */
 320
 321         need_in = !cmd->no_stdin && cmd->in < 0;
 322         if (need_in) {
 323                 if (pipe(fdin) < 0) {
 324                         failed_errno = errno;
 325                         if (cmd->out > 0)
 326                                 close(cmd->out);
 327                         str = "standard input";
 328                         goto fail_pipe;
 329                 }
 330                 cmd->in = fdin[1];
 331         }
 332
 333         need_out = !cmd->no_stdout
 334                 && !cmd->stdout_to_stderr
 335                 && cmd->out < 0;
 336         if (need_out) {
 337                 if (pipe(fdout) < 0) {
 338                         failed_errno = errno;
 339                         if (need_in)
 340                                 close_pair(fdin);
 341                         else if (cmd->in)
 342                                 close(cmd->in);
 343                         str = "standard output";
 344                         goto fail_pipe;
 345                 }
 346                 cmd->out = fdout[0];
 347         }
 348
 349         need_err = !cmd->no_stderr && cmd->err < 0;
 350         if (need_err) {
 351                 if (pipe(fderr) < 0) {
 352                         failed_errno = errno;
 353                         if (need_in)
 354                                 close_pair(fdin);
 355                         else if (cmd->in)
 356                                 close(cmd->in);
 357                         if (need_out)
 358                                 close_pair(fdout);
 359                         else if (cmd->out)
 360                                 close(cmd->out);
 361                         str = "standard error";
 362 fail_pipe:
 363                         error("cannot create %s pipe for %s: %s",
 364                                 str, cmd->argv[0], strerror(failed_errno));
 365                         child_process_clear(cmd);
 366                         errno = failed_errno;
 367                         return -1;
 368                 }
 369                 cmd->err = fderr[0];
 370         }
 371
 372         trace_argv_printf(cmd->argv, "trace: run_command:");
 373         fflush(NULL);
 374
 375 #ifndef GIT_WINDOWS_NATIVE
 376 {
 377         int notify_pipe[2];
 378         struct argv_array argv = ARGV_ARRAY_INIT;
 379
 380         if (pipe(notify_pipe))
 381                 notify_pipe[0] = notify_pipe[1] = -1;
 382
 383         prepare_cmd(&argv, cmd);
 384
 385         cmd->pid = fork();
 386         failed_errno = errno;
 387         if (!cmd->pid) {
 388                 /*
 389                  * Redirect the channel to write syscall error messages to
 390                  * before redirecting the process's stderr so that all die()
 391                  * in subsequent call paths use the parent's stderr.
 392                  */
 393                 if (cmd->no_stderr || need_err) {
 394                         int child_err = dup(2);
 395                         set_cloexec(child_err);
 396                         set_error_handle(fdopen(child_err, "w"));
 397                 }
 398
 399                 close(notify_pipe[0]);
 400                 set_cloexec(notify_pipe[1]);
 401                 child_notifier = notify_pipe[1];
 402                 atexit(notify_parent);
 403
 404                 if (cmd->no_stdin)
 405                         dup_devnull(0);
 406                 else if (need_in) {
 407                         dup2(fdin[0], 0);
 408                         close_pair(fdin);
 409                 } else if (cmd->in) {
 410                         dup2(cmd->in, 0);
 411                         close(cmd->in);
 412                 }
 413
 414                 if (cmd->no_stderr)
 415                         dup_devnull(2);
 416                 else if (need_err) {
 417                         dup2(fderr[1], 2);
 418                         close_pair(fderr);
 419                 } else if (cmd->err > 1) {
 420                         dup2(cmd->err, 2);
 421                         close(cmd->err);
 422                 }
 423
 424                 if (cmd->no_stdout)
 425                         dup_devnull(1);
 426                 else if (cmd->stdout_to_stderr)
 427                         dup2(2, 1);
 428                 else if (need_out) {
 429                         dup2(fdout[1], 1);
 430                         close_pair(fdout);
 431                 } else if (cmd->out > 1) {
 432                         dup2(cmd->out, 1);
 433                         close(cmd->out);
 434                 }
 435
 436                 if (cmd->dir && chdir(cmd->dir))
 437                         die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 438                             cmd->dir);
 439                 if (cmd->env) {
 440                         for (; *cmd->env; cmd->env++) {
 441                                 if (strchr(*cmd->env, '='))
 442                                         putenv((char *)*cmd->env);
 443                                 else
 444                                         unsetenv(*cmd->env);
 445                         }
 446                 }
 447
 448                 sane_execvp(argv.argv[0], (char *const *) argv.argv);
 449
 450                 if (errno == ENOENT) {
 451                         if (!cmd->silent_exec_failure)
 452                                 error("cannot run %s: %s", cmd->argv[0],
 453                                         strerror(ENOENT));
 454                         exit(127);
 455                 } else {
 456                         die_errno("cannot exec '%s'", cmd->argv[0]);
 457                 }
 458         }
 459         if (cmd->pid < 0)
 460                 error_errno("cannot fork() for %s", cmd->argv[0]);
 461         else if (cmd->clean_on_exit)
 462                 mark_child_for_cleanup(cmd->pid, cmd);
 463
 464         /*
 465          * Wait for child's exec. If the exec succeeds (or if fork()
 466          * failed), EOF is seen immediately by the parent. Otherwise, the
 467          * child process sends a single byte.
 468          * Note that use of this infrastructure is completely advisory,
 469          * therefore, we keep error checks minimal.
 470          */
 471         close(notify_pipe[1]);
 472         if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 473                 /*
 474                  * At this point we know that fork() succeeded, but exec()
 475                  * failed. Errors have been reported to our stderr.
 476                  */
 477                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 478                 failed_errno = errno;
 479                 cmd->pid = -1;
 480         }
 481         close(notify_pipe[0]);
 482
 483         argv_array_clear(&argv);
 484 }
 485 #else
 486 {
 487         int fhin = 0, fhout = 1, fherr = 2;
 488         const char **sargv = cmd->argv;
 489         struct argv_array nargv = ARGV_ARRAY_INIT;
 490
 491         if (cmd->no_stdin)
 492                 fhin = open("/dev/null", O_RDWR);
 493         else if (need_in)
 494                 fhin = dup(fdin[0]);
 495         else if (cmd->in)
 496                 fhin = dup(cmd->in);
 497
 498         if (cmd->no_stderr)
 499                 fherr = open("/dev/null", O_RDWR);
 500         else if (need_err)
 501                 fherr = dup(fderr[1]);
 502         else if (cmd->err > 2)
 503                 fherr = dup(cmd->err);
 504
 505         if (cmd->no_stdout)
 506                 fhout = open("/dev/null", O_RDWR);
 507         else if (cmd->stdout_to_stderr)
 508                 fhout = dup(fherr);
 509         else if (need_out)
 510                 fhout = dup(fdout[1]);
 511         else if (cmd->out > 1)
 512                 fhout = dup(cmd->out);
 513
 514         if (cmd->git_cmd)
 515                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 516         else if (cmd->use_shell)
 517                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 518
 519         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 520                         cmd->dir, fhin, fhout, fherr);
 521         failed_errno = errno;
 522         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 523                 error_errno("cannot spawn %s", cmd->argv[0]);
 524         if (cmd->clean_on_exit && cmd->pid >= 0)
 525                 mark_child_for_cleanup(cmd->pid, cmd);
 526
 527         argv_array_clear(&nargv);
 528         cmd->argv = sargv;
 529         if (fhin != 0)
 530                 close(fhin);
 531         if (fhout != 1)
 532                 close(fhout);
 533         if (fherr != 2)
 534                 close(fherr);
 535 }
 536 #endif
 537
 538         if (cmd->pid < 0) {
 539                 if (need_in)
 540                         close_pair(fdin);
 541                 else if (cmd->in)
 542                         close(cmd->in);
 543                 if (need_out)
 544                         close_pair(fdout);
 545                 else if (cmd->out)
 546                         close(cmd->out);
 547                 if (need_err)
 548                         close_pair(fderr);
 549                 else if (cmd->err)
 550                         close(cmd->err);
 551                 child_process_clear(cmd);
 552                 errno = failed_errno;
 553                 return -1;
 554         }
 555
 556         if (need_in)
 557                 close(fdin[0]);
 558         else if (cmd->in)
 559                 close(cmd->in);
 560
 561         if (need_out)
 562                 close(fdout[1]);
 563         else if (cmd->out)
 564                 close(cmd->out);
 565
 566         if (need_err)
 567                 close(fderr[1]);
 568         else if (cmd->err)
 569                 close(cmd->err);
 570
 571         return 0;
 572 }
 573
 574 int finish_command(struct child_process *cmd)
 575 {
 576         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 577         child_process_clear(cmd);
 578         return ret;
 579 }
 580
 581 int finish_command_in_signal(struct child_process *cmd)
 582 {
 583         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 584 }
 585
 586
 587 int run_command(struct child_process *cmd)
 588 {
 589         int code;
 590
 591         if (cmd->out < 0 || cmd->err < 0)
 592                 die("BUG: run_command with a pipe can cause deadlock");
 593
 594         code = start_command(cmd);
 595         if (code)
 596                 return code;
 597         return finish_command(cmd);
 598 }
 599
 600 int run_command_v_opt(const char **argv, int opt)
 601 {
 602         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 603 }
 604
 605 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 606 {
 607         struct child_process cmd = CHILD_PROCESS_INIT;
 608         cmd.argv = argv;
 609         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 610         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 611         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 612         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 613         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 614         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 615         cmd.dir = dir;
 616         cmd.env = env;
 617         return run_command(&cmd);
 618 }
 619
 620 #ifndef NO_PTHREADS
 621 static pthread_t main_thread;
 622 static int main_thread_set;
 623 static pthread_key_t async_key;
 624 static pthread_key_t async_die_counter;
 625
 626 static void *run_thread(void *data)
 627 {
 628         struct async *async = data;
 629         intptr_t ret;
 630
 631         if (async->isolate_sigpipe) {
 632                 sigset_t mask;
 633                 sigemptyset(&mask);
 634                 sigaddset(&mask, SIGPIPE);
 635                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 636                         ret = error("unable to block SIGPIPE in async thread");
 637                         return (void *)ret;
 638                 }
 639         }
 640
 641         pthread_setspecific(async_key, async);
 642         ret = async->proc(async->proc_in, async->proc_out, async->data);
 643         return (void *)ret;
 644 }
 645
 646 static NORETURN void die_async(const char *err, va_list params)
 647 {
 648         vreportf("fatal: ", err, params);
 649
 650         if (in_async()) {
 651                 struct async *async = pthread_getspecific(async_key);
 652                 if (async->proc_in >= 0)
 653                         close(async->proc_in);
 654                 if (async->proc_out >= 0)
 655                         close(async->proc_out);
 656                 pthread_exit((void *)128);
 657         }
 658
 659         exit(128);
 660 }
 661
 662 static int async_die_is_recursing(void)
 663 {
 664         void *ret = pthread_getspecific(async_die_counter);
 665         pthread_setspecific(async_die_counter, (void *)1);
 666         return ret != NULL;
 667 }
 668
 669 int in_async(void)
 670 {
 671         if (!main_thread_set)
 672                 return 0; /* no asyncs started yet */
 673         return !pthread_equal(main_thread, pthread_self());
 674 }
 675
 676 static void NORETURN async_exit(int code)
 677 {
 678         pthread_exit((void *)(intptr_t)code);
 679 }
 680
 681 #else
 682
 683 static struct {
 684         void (**handlers)(void);
 685         size_t nr;
 686         size_t alloc;
 687 } git_atexit_hdlrs;
 688
 689 static int git_atexit_installed;
 690
 691 static void git_atexit_dispatch(void)
 692 {
 693         size_t i;
 694
 695         for (i=git_atexit_hdlrs.nr ; i ; i--)
 696                 git_atexit_hdlrs.handlers[i-1]();
 697 }
 698
 699 static void git_atexit_clear(void)
 700 {
 701         free(git_atexit_hdlrs.handlers);
 702         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 703         git_atexit_installed = 0;
 704 }
 705
 706 #undef atexit
 707 int git_atexit(void (*handler)(void))
 708 {
 709         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 710         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 711         if (!git_atexit_installed) {
 712                 if (atexit(&git_atexit_dispatch))
 713                         return -1;
 714                 git_atexit_installed = 1;
 715         }
 716         return 0;
 717 }
 718 #define atexit git_atexit
 719
 720 static int process_is_async;
 721 int in_async(void)
 722 {
 723         return process_is_async;
 724 }
 725
 726 static void NORETURN async_exit(int code)
 727 {
 728         exit(code);
 729 }
 730
 731 #endif
 732
 733 void check_pipe(int err)
 734 {
 735         if (err == EPIPE) {
 736                 if (in_async())
 737                         async_exit(141);
 738
 739                 signal(SIGPIPE, SIG_DFL);
 740                 raise(SIGPIPE);
 741                 /* Should never happen, but just in case... */
 742                 exit(141);
 743         }
 744 }
 745
 746 int start_async(struct async *async)
 747 {
 748         int need_in, need_out;
 749         int fdin[2], fdout[2];
 750         int proc_in, proc_out;
 751
 752         need_in = async->in < 0;
 753         if (need_in) {
 754                 if (pipe(fdin) < 0) {
 755                         if (async->out > 0)
 756                                 close(async->out);
 757                         return error_errno("cannot create pipe");
 758                 }
 759                 async->in = fdin[1];
 760         }
 761
 762         need_out = async->out < 0;
 763         if (need_out) {
 764                 if (pipe(fdout) < 0) {
 765                         if (need_in)
 766                                 close_pair(fdin);
 767                         else if (async->in)
 768                                 close(async->in);
 769                         return error_errno("cannot create pipe");
 770                 }
 771                 async->out = fdout[0];
 772         }
 773
 774         if (need_in)
 775                 proc_in = fdin[0];
 776         else if (async->in)
 777                 proc_in = async->in;
 778         else
 779                 proc_in = -1;
 780
 781         if (need_out)
 782                 proc_out = fdout[1];
 783         else if (async->out)
 784                 proc_out = async->out;
 785         else
 786                 proc_out = -1;
 787
 788 #ifdef NO_PTHREADS
 789         /* Flush stdio before fork() to avoid cloning buffers */
 790         fflush(NULL);
 791
 792         async->pid = fork();
 793         if (async->pid < 0) {
 794                 error_errno("fork (async) failed");
 795                 goto error;
 796         }
 797         if (!async->pid) {
 798                 if (need_in)
 799                         close(fdin[1]);
 800                 if (need_out)
 801                         close(fdout[0]);
 802                 git_atexit_clear();
 803                 process_is_async = 1;
 804                 exit(!!async->proc(proc_in, proc_out, async->data));
 805         }
 806
 807         mark_child_for_cleanup(async->pid, NULL);
 808
 809         if (need_in)
 810                 close(fdin[0]);
 811         else if (async->in)
 812                 close(async->in);
 813
 814         if (need_out)
 815                 close(fdout[1]);
 816         else if (async->out)
 817                 close(async->out);
 818 #else
 819         if (!main_thread_set) {
 820                 /*
 821                  * We assume that the first time that start_async is called
 822                  * it is from the main thread.
 823                  */
 824                 main_thread_set = 1;
 825                 main_thread = pthread_self();
 826                 pthread_key_create(&async_key, NULL);
 827                 pthread_key_create(&async_die_counter, NULL);
 828                 set_die_routine(die_async);
 829                 set_die_is_recursing_routine(async_die_is_recursing);
 830         }
 831
 832         if (proc_in >= 0)
 833                 set_cloexec(proc_in);
 834         if (proc_out >= 0)
 835                 set_cloexec(proc_out);
 836         async->proc_in = proc_in;
 837         async->proc_out = proc_out;
 838         {
 839                 int err = pthread_create(&async->tid, NULL, run_thread, async);
 840                 if (err) {
 841                         error_errno("cannot create thread");
 842                         goto error;
 843                 }
 844         }
 845 #endif
 846         return 0;
 847
 848 error:
 849         if (need_in)
 850                 close_pair(fdin);
 851         else if (async->in)
 852                 close(async->in);
 853
 854         if (need_out)
 855                 close_pair(fdout);
 856         else if (async->out)
 857                 close(async->out);
 858         return -1;
 859 }
 860
 861 int finish_async(struct async *async)
 862 {
 863 #ifdef NO_PTHREADS
 864         return wait_or_whine(async->pid, "child process", 0);
 865 #else
 866         void *ret = (void *)(intptr_t)(-1);
 867
 868         if (pthread_join(async->tid, &ret))
 869                 error("pthread_join failed");
 870         return (int)(intptr_t)ret;
 871 #endif
 872 }
 873
 874 const char *find_hook(const char *name)
 875 {
 876         static struct strbuf path = STRBUF_INIT;
 877
 878         strbuf_reset(&path);
 879         strbuf_git_path(&path, "hooks/%s", name);
 880         if (access(path.buf, X_OK) < 0) {
 881 #ifdef STRIP_EXTENSION
 882                 strbuf_addstr(&path, STRIP_EXTENSION);
 883                 if (access(path.buf, X_OK) >= 0)
 884                         return path.buf;
 885 #endif
 886                 return NULL;
 887         }
 888         return path.buf;
 889 }
 890
 891 int run_hook_ve(const char *const *env, const char *name, va_list args)
 892 {
 893         struct child_process hook = CHILD_PROCESS_INIT;
 894         const char *p;
 895
 896         p = find_hook(name);
 897         if (!p)
 898                 return 0;
 899
 900         argv_array_push(&hook.args, p);
 901         while ((p = va_arg(args, const char *)))
 902                 argv_array_push(&hook.args, p);
 903         hook.env = env;
 904         hook.no_stdin = 1;
 905         hook.stdout_to_stderr = 1;
 906
 907         return run_command(&hook);
 908 }
 909
 910 int run_hook_le(const char *const *env, const char *name, ...)
 911 {
 912         va_list args;
 913         int ret;
 914
 915         va_start(args, name);
 916         ret = run_hook_ve(env, name, args);
 917         va_end(args);
 918
 919         return ret;
 920 }
 921
 922 struct io_pump {
 923         /* initialized by caller */
 924         int fd;
 925         int type; /* POLLOUT or POLLIN */
 926         union {
 927                 struct {
 928                         const char *buf;
 929                         size_t len;
 930                 } out;
 931                 struct {
 932                         struct strbuf *buf;
 933                         size_t hint;
 934                 } in;
 935         } u;
 936
 937         /* returned by pump_io */
 938         int error; /* 0 for success, otherwise errno */
 939
 940         /* internal use */
 941         struct pollfd *pfd;
 942 };
 943
 944 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
 945 {
 946         int pollsize = 0;
 947         int i;
 948
 949         for (i = 0; i < nr; i++) {
 950                 struct io_pump *io = &slots[i];
 951                 if (io->fd < 0)
 952                         continue;
 953                 pfd[pollsize].fd = io->fd;
 954                 pfd[pollsize].events = io->type;
 955                 io->pfd = &pfd[pollsize++];
 956         }
 957
 958         if (!pollsize)
 959                 return 0;
 960
 961         if (poll(pfd, pollsize, -1) < 0) {
 962                 if (errno == EINTR)
 963                         return 1;
 964                 die_errno("poll failed");
 965         }
 966
 967         for (i = 0; i < nr; i++) {
 968                 struct io_pump *io = &slots[i];
 969
 970                 if (io->fd < 0)
 971                         continue;
 972
 973                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
 974                         continue;
 975
 976                 if (io->type == POLLOUT) {
 977                         ssize_t len = xwrite(io->fd,
 978                                              io->u.out.buf, io->u.out.len);
 979                         if (len < 0) {
 980                                 io->error = errno;
 981                                 close(io->fd);
 982                                 io->fd = -1;
 983                         } else {
 984                                 io->u.out.buf += len;
 985                                 io->u.out.len -= len;
 986                                 if (!io->u.out.len) {
 987                                         close(io->fd);
 988                                         io->fd = -1;
 989                                 }
 990                         }
 991                 }
 992
 993                 if (io->type == POLLIN) {
 994                         ssize_t len = strbuf_read_once(io->u.in.buf,
 995                                                        io->fd, io->u.in.hint);
 996                         if (len < 0)
 997                                 io->error = errno;
 998                         if (len <= 0) {
 999                                 close(io->fd);
1000                                 io->fd = -1;
1001                         }
1002                 }
1003         }
1004
1005         return 1;
1006 }
1007
1008 static int pump_io(struct io_pump *slots, int nr)
1009 {
1010         struct pollfd *pfd;
1011         int i;
1012
1013         for (i = 0; i < nr; i++)
1014                 slots[i].error = 0;
1015
1016         ALLOC_ARRAY(pfd, nr);
1017         while (pump_io_round(slots, nr, pfd))
1018                 ; /* nothing */
1019         free(pfd);
1020
1021         /* There may be multiple errno values, so just pick the first. */
1022         for (i = 0; i < nr; i++) {
1023                 if (slots[i].error) {
1024                         errno = slots[i].error;
1025                         return -1;
1026                 }
1027         }
1028         return 0;
1029 }
1030
1031
1032 int pipe_command(struct child_process *cmd,
1033                  const char *in, size_t in_len,
1034                  struct strbuf *out, size_t out_hint,
1035                  struct strbuf *err, size_t err_hint)
1036 {
1037         struct io_pump io[3];
1038         int nr = 0;
1039
1040         if (in)
1041                 cmd->in = -1;
1042         if (out)
1043                 cmd->out = -1;
1044         if (err)
1045                 cmd->err = -1;
1046
1047         if (start_command(cmd) < 0)
1048                 return -1;
1049
1050         if (in) {
1051                 io[nr].fd = cmd->in;
1052                 io[nr].type = POLLOUT;
1053                 io[nr].u.out.buf = in;
1054                 io[nr].u.out.len = in_len;
1055                 nr++;
1056         }
1057         if (out) {
1058                 io[nr].fd = cmd->out;
1059                 io[nr].type = POLLIN;
1060                 io[nr].u.in.buf = out;
1061                 io[nr].u.in.hint = out_hint;
1062                 nr++;
1063         }
1064         if (err) {
1065                 io[nr].fd = cmd->err;
1066                 io[nr].type = POLLIN;
1067                 io[nr].u.in.buf = err;
1068                 io[nr].u.in.hint = err_hint;
1069                 nr++;
1070         }
1071
1072         if (pump_io(io, nr) < 0) {
1073                 finish_command(cmd); /* throw away exit code */
1074                 return -1;
1075         }
1076
1077         return finish_command(cmd);
1078 }
1079
1080 enum child_state {
1081         GIT_CP_FREE,
1082         GIT_CP_WORKING,
1083         GIT_CP_WAIT_CLEANUP,
1084 };
1085
1086 struct parallel_processes {
1087         void *data;
1088
1089         int max_processes;
1090         int nr_processes;
1091
1092         get_next_task_fn get_next_task;
1093         start_failure_fn start_failure;
1094         task_finished_fn task_finished;
1095
1096         struct {
1097                 enum child_state state;
1098                 struct child_process process;
1099                 struct strbuf err;
1100                 void *data;
1101         } *children;
1102         /*
1103          * The struct pollfd is logically part of *children,
1104          * but the system call expects it as its own array.
1105          */
1106         struct pollfd *pfd;
1107
1108         unsigned shutdown : 1;
1109
1110         int output_owner;
1111         struct strbuf buffered_output; /* of finished children */
1112 };
1113
1114 static int default_start_failure(struct strbuf *out,
1115                                  void *pp_cb,
1116                                  void *pp_task_cb)
1117 {
1118         return 0;
1119 }
1120
1121 static int default_task_finished(int result,
1122                                  struct strbuf *out,
1123                                  void *pp_cb,
1124                                  void *pp_task_cb)
1125 {
1126         return 0;
1127 }
1128
1129 static void kill_children(struct parallel_processes *pp, int signo)
1130 {
1131         int i, n = pp->max_processes;
1132
1133         for (i = 0; i < n; i++)
1134                 if (pp->children[i].state == GIT_CP_WORKING)
1135                         kill(pp->children[i].process.pid, signo);
1136 }
1137
1138 static struct parallel_processes *pp_for_signal;
1139
1140 static void handle_children_on_signal(int signo)
1141 {
1142         kill_children(pp_for_signal, signo);
1143         sigchain_pop(signo);
1144         raise(signo);
1145 }
1146
1147 static void pp_init(struct parallel_processes *pp,
1148                     int n,
1149                     get_next_task_fn get_next_task,
1150                     start_failure_fn start_failure,
1151                     task_finished_fn task_finished,
1152                     void *data)
1153 {
1154         int i;
1155
1156         if (n < 1)
1157                 n = online_cpus();
1158
1159         pp->max_processes = n;
1160
1161         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1162
1163         pp->data = data;
1164         if (!get_next_task)
1165                 die("BUG: you need to specify a get_next_task function");
1166         pp->get_next_task = get_next_task;
1167
1168         pp->start_failure = start_failure ? start_failure : default_start_failure;
1169         pp->task_finished = task_finished ? task_finished : default_task_finished;
1170
1171         pp->nr_processes = 0;
1172         pp->output_owner = 0;
1173         pp->shutdown = 0;
1174         pp->children = xcalloc(n, sizeof(*pp->children));
1175         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1176         strbuf_init(&pp->buffered_output, 0);
1177
1178         for (i = 0; i < n; i++) {
1179                 strbuf_init(&pp->children[i].err, 0);
1180                 child_process_init(&pp->children[i].process);
1181                 pp->pfd[i].events = POLLIN | POLLHUP;
1182                 pp->pfd[i].fd = -1;
1183         }
1184
1185         pp_for_signal = pp;
1186         sigchain_push_common(handle_children_on_signal);
1187 }
1188
1189 static void pp_cleanup(struct parallel_processes *pp)
1190 {
1191         int i;
1192
1193         trace_printf("run_processes_parallel: done");
1194         for (i = 0; i < pp->max_processes; i++) {
1195                 strbuf_release(&pp->children[i].err);
1196                 child_process_clear(&pp->children[i].process);
1197         }
1198
1199         free(pp->children);
1200         free(pp->pfd);
1201
1202         /*
1203          * When get_next_task added messages to the buffer in its last
1204          * iteration, the buffered output is non empty.
1205          */
1206         strbuf_write(&pp->buffered_output, stderr);
1207         strbuf_release(&pp->buffered_output);
1208
1209         sigchain_pop_common();
1210 }
1211
1212 /* returns
1213  *  0 if a new task was started.
1214  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1215  *    problem with starting a new command)
1216  * <0 no new job was started, user wishes to shutdown early. Use negative code
1217  *    to signal the children.
1218  */
1219 static int pp_start_one(struct parallel_processes *pp)
1220 {
1221         int i, code;
1222
1223         for (i = 0; i < pp->max_processes; i++)
1224                 if (pp->children[i].state == GIT_CP_FREE)
1225                         break;
1226         if (i == pp->max_processes)
1227                 die("BUG: bookkeeping is hard");
1228
1229         code = pp->get_next_task(&pp->children[i].process,
1230                                  &pp->children[i].err,
1231                                  pp->data,
1232                                  &pp->children[i].data);
1233         if (!code) {
1234                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1235                 strbuf_reset(&pp->children[i].err);
1236                 return 1;
1237         }
1238         pp->children[i].process.err = -1;
1239         pp->children[i].process.stdout_to_stderr = 1;
1240         pp->children[i].process.no_stdin = 1;
1241
1242         if (start_command(&pp->children[i].process)) {
1243                 code = pp->start_failure(&pp->children[i].err,
1244                                          pp->data,
1245                                          &pp->children[i].data);
1246                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1247                 strbuf_reset(&pp->children[i].err);
1248                 if (code)
1249                         pp->shutdown = 1;
1250                 return code;
1251         }
1252
1253         pp->nr_processes++;
1254         pp->children[i].state = GIT_CP_WORKING;
1255         pp->pfd[i].fd = pp->children[i].process.err;
1256         return 0;
1257 }
1258
1259 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1260 {
1261         int i;
1262
1263         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1264                 if (errno == EINTR)
1265                         continue;
1266                 pp_cleanup(pp);
1267                 die_errno("poll");
1268         }
1269
1270         /* Buffer output from all pipes. */
1271         for (i = 0; i < pp->max_processes; i++) {
1272                 if (pp->children[i].state == GIT_CP_WORKING &&
1273                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1274                         int n = strbuf_read_once(&pp->children[i].err,
1275                                                  pp->children[i].process.err, 0);
1276                         if (n == 0) {
1277                                 close(pp->children[i].process.err);
1278                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1279                         } else if (n < 0)
1280                                 if (errno != EAGAIN)
1281                                         die_errno("read");
1282                 }
1283         }
1284 }
1285
1286 static void pp_output(struct parallel_processes *pp)
1287 {
1288         int i = pp->output_owner;
1289         if (pp->children[i].state == GIT_CP_WORKING &&
1290             pp->children[i].err.len) {
1291                 strbuf_write(&pp->children[i].err, stderr);
1292                 strbuf_reset(&pp->children[i].err);
1293         }
1294 }
1295
1296 static int pp_collect_finished(struct parallel_processes *pp)
1297 {
1298         int i, code;
1299         int n = pp->max_processes;
1300         int result = 0;
1301
1302         while (pp->nr_processes > 0) {
1303                 for (i = 0; i < pp->max_processes; i++)
1304                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1305                                 break;
1306                 if (i == pp->max_processes)
1307                         break;
1308
1309                 code = finish_command(&pp->children[i].process);
1310
1311                 code = pp->task_finished(code,
1312                                          &pp->children[i].err, pp->data,
1313                                          &pp->children[i].data);
1314
1315                 if (code)
1316                         result = code;
1317                 if (code < 0)
1318                         break;
1319
1320                 pp->nr_processes--;
1321                 pp->children[i].state = GIT_CP_FREE;
1322                 pp->pfd[i].fd = -1;
1323                 child_process_init(&pp->children[i].process);
1324
1325                 if (i != pp->output_owner) {
1326                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1327                         strbuf_reset(&pp->children[i].err);
1328                 } else {
1329                         strbuf_write(&pp->children[i].err, stderr);
1330                         strbuf_reset(&pp->children[i].err);
1331
1332                         /* Output all other finished child processes */
1333                         strbuf_write(&pp->buffered_output, stderr);
1334                         strbuf_reset(&pp->buffered_output);
1335
1336                         /*
1337                          * Pick next process to output live.
1338                          * NEEDSWORK:
1339                          * For now we pick it randomly by doing a round
1340                          * robin. Later we may want to pick the one with
1341                          * the most output or the longest or shortest
1342                          * running process time.
1343                          */
1344                         for (i = 0; i < n; i++)
1345                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1346                                         break;
1347                         pp->output_owner = (pp->output_owner + i) % n;
1348                 }
1349         }
1350         return result;
1351 }
1352
1353 int run_processes_parallel(int n,
1354                            get_next_task_fn get_next_task,
1355                            start_failure_fn start_failure,
1356                            task_finished_fn task_finished,
1357                            void *pp_cb)
1358 {
1359         int i, code;
1360         int output_timeout = 100;
1361         int spawn_cap = 4;
1362         struct parallel_processes pp;
1363
1364         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1365         while (1) {
1366                 for (i = 0;
1367                     i < spawn_cap && !pp.shutdown &&
1368                     pp.nr_processes < pp.max_processes;
1369                     i++) {
1370                         code = pp_start_one(&pp);
1371                         if (!code)
1372                                 continue;
1373                         if (code < 0) {
1374                                 pp.shutdown = 1;
1375                                 kill_children(&pp, -code);
1376                         }
1377                         break;
1378                 }
1379                 if (!pp.nr_processes)
1380                         break;
1381                 pp_buffer_stderr(&pp, output_timeout);
1382                 pp_output(&pp);
1383                 code = pp_collect_finished(&pp);
1384                 if (code) {
1385                         pp.shutdown = 1;
1386                         if (code < 0)
1387                                 kill_children(&pp, -code);
1388                 }
1389         }
1390
1391         pp_cleanup(&pp);
1392         return 0;
1393 }