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