git.oblomov.eu Git - git/blob - 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 static char *locate_in_PATH(const char *file)
 121 {
 122         const char *p = getenv("PATH");
 123         struct strbuf buf = STRBUF_INIT;
 124
 125         if (!p || !*p)
 126                 return NULL;
 127
 128         while (1) {
 129                 const char *end = strchrnul(p, ':');
 130
 131                 strbuf_reset(&buf);
 132
 133                 /* POSIX specifies an empty entry as the current directory. */
 134                 if (end != p) {
 135                         strbuf_add(&buf, p, end - p);
 136                         strbuf_addch(&buf, '/');
 137                 }
 138                 strbuf_addstr(&buf, file);
 139
 140                 if (!access(buf.buf, F_OK))
 141                         return strbuf_detach(&buf, NULL);
 142
 143                 if (!*end)
 144                         break;
 145                 p = end + 1;
 146         }
 147
 148         strbuf_release(&buf);
 149         return NULL;
 150 }
 151
 152 static int exists_in_PATH(const char *file)
 153 {
 154         char *r = locate_in_PATH(file);
 155         free(r);
 156         return r != NULL;
 157 }
 158
 159 int sane_execvp(const char *file, char * const argv[])
 160 {
 161         if (!execvp(file, argv))
 162                 return 0; /* cannot happen ;-) */
 163
 164         /*
 165          * When a command can't be found because one of the directories
 166          * listed in $PATH is unsearchable, execvp reports EACCES, but
 167          * careful usability testing (read: analysis of occasional bug
 168          * reports) reveals that "No such file or directory" is more
 169          * intuitive.
 170          *
 171          * We avoid commands with "/", because execvp will not do $PATH
 172          * lookups in that case.
 173          *
 174          * The reassignment of EACCES to errno looks like a no-op below,
 175          * but we need to protect against exists_in_PATH overwriting errno.
 176          */
 177         if (errno == EACCES && !strchr(file, '/'))
 178                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 179         else if (errno == ENOTDIR && !strchr(file, '/'))
 180                 errno = ENOENT;
 181         return -1;
 182 }
 183
 184 static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 185 {
 186         if (!argv[0])
 187                 die("BUG: shell command is empty");
 188
 189         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 190 #ifndef GIT_WINDOWS_NATIVE
 191                 argv_array_push(out, SHELL_PATH);
 192 #else
 193                 argv_array_push(out, "sh");
 194 #endif
 195                 argv_array_push(out, "-c");
 196
 197                 /*
 198                  * If we have no extra arguments, we do not even need to
 199                  * bother with the "$@" magic.
 200                  */
 201                 if (!argv[1])
 202                         argv_array_push(out, argv[0]);
 203                 else
 204                         argv_array_pushf(out, "%s \"$@\"", argv[0]);
 205         }
 206
 207         argv_array_pushv(out, argv);
 208         return out->argv;
 209 }
 210
 211 #ifndef GIT_WINDOWS_NATIVE
 212 static int child_notifier = -1;
 213
 214 static void notify_parent(void)
 215 {
 216         /*
 217          * execvp failed.  If possible, we'd like to let start_command
 218          * know, so failures like ENOENT can be handled right away; but
 219          * otherwise, finish_command will still report the error.
 220          */
 221         xwrite(child_notifier, "", 1);
 222 }
 223
 224 static void prepare_cmd(struct argv_array *out, const struct child_process *cmd)
 225 {
 226         if (!cmd->argv[0])
 227                 die("BUG: command is empty");
 228
 229         /*
 230          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 231          * attempt to interpret the command with 'sh'.
 232          */
 233         argv_array_push(out, SHELL_PATH);
 234
 235         if (cmd->git_cmd) {
 236                 argv_array_push(out, "git");
 237                 argv_array_pushv(out, cmd->argv);
 238         } else if (cmd->use_shell) {
 239                 prepare_shell_cmd(out, cmd->argv);
 240         } else {
 241                 argv_array_pushv(out, cmd->argv);
 242         }
 243
 244         /*
 245          * If there are no '/' characters in the command then perform a path
 246          * lookup and use the resolved path as the command to exec.  If there
 247          * are no '/' characters or if the command wasn't found in the path,
 248          * have exec attempt to invoke the command directly.
 249          */
 250         if (!strchr(out->argv[1], '/')) {
 251                 char *program = locate_in_PATH(out->argv[1]);
 252                 if (program) {
 253                         free((char *)out->argv[1]);
 254                         out->argv[1] = program;
 255                 }
 256         }
 257 }
 258
 259 static char **prep_childenv(const char *const *deltaenv)
 260 {
 261         extern char **environ;
 262         char **childenv;
 263         struct string_list env = STRING_LIST_INIT_DUP;
 264         struct strbuf key = STRBUF_INIT;
 265         const char *const *p;
 266         int i;
 267
 268         /* Construct a sorted string list consisting of the current environ */
 269         for (p = (const char *const *) environ; p && *p; p++) {
 270                 const char *equals = strchr(*p, '=');
 271
 272                 if (equals) {
 273                         strbuf_reset(&key);
 274                         strbuf_add(&key, *p, equals - *p);
 275                         string_list_append(&env, key.buf)->util = (void *) *p;
 276                 } else {
 277                         string_list_append(&env, *p)->util = (void *) *p;
 278                 }
 279         }
 280         string_list_sort(&env);
 281
 282         /* Merge in 'deltaenv' with the current environ */
 283         for (p = deltaenv; p && *p; p++) {
 284                 const char *equals = strchr(*p, '=');
 285
 286                 if (equals) {
 287                         /* ('key=value'), insert or replace entry */
 288                         strbuf_reset(&key);
 289                         strbuf_add(&key, *p, equals - *p);
 290                         string_list_insert(&env, key.buf)->util = (void *) *p;
 291                 } else {
 292                         /* otherwise ('key') remove existing entry */
 293                         string_list_remove(&env, *p, 0);
 294                 }
 295         }
 296
 297         /* Create an array of 'char *' to be used as the childenv */
 298         childenv = xmalloc((env.nr + 1) * sizeof(char *));
 299         for (i = 0; i < env.nr; i++)
 300                 childenv[i] = env.items[i].util;
 301         childenv[env.nr] = NULL;
 302
 303         string_list_clear(&env, 0);
 304         strbuf_release(&key);
 305         return childenv;
 306 }
 307 #endif
 308
 309 static inline void set_cloexec(int fd)
 310 {
 311         int flags = fcntl(fd, F_GETFD);
 312         if (flags >= 0)
 313                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 314 }
 315
 316 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 317 {
 318         int status, code = -1;
 319         pid_t waiting;
 320         int failed_errno = 0;
 321
 322         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 323                 ;       /* nothing */
 324         if (in_signal)
 325                 return 0;
 326
 327         if (waiting < 0) {
 328                 failed_errno = errno;
 329                 error_errno("waitpid for %s failed", argv0);
 330         } else if (waiting != pid) {
 331                 error("waitpid is confused (%s)", argv0);
 332         } else if (WIFSIGNALED(status)) {
 333                 code = WTERMSIG(status);
 334                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 335                         error("%s died of signal %d", argv0, code);
 336                 /*
 337                  * This return value is chosen so that code & 0xff
 338                  * mimics the exit code that a POSIX shell would report for
 339                  * a program that died from this signal.
 340                  */
 341                 code += 128;
 342         } else if (WIFEXITED(status)) {
 343                 code = WEXITSTATUS(status);
 344                 /*
 345                  * Convert special exit code when execvp failed.
 346                  */
 347                 if (code == 127) {
 348                         code = -1;
 349                         failed_errno = ENOENT;
 350                 }
 351         } else {
 352                 error("waitpid is confused (%s)", argv0);
 353         }
 354
 355         clear_child_for_cleanup(pid);
 356
 357         errno = failed_errno;
 358         return code;
 359 }
 360
 361 int start_command(struct child_process *cmd)
 362 {
 363         int need_in, need_out, need_err;
 364         int fdin[2], fdout[2], fderr[2];
 365         int failed_errno;
 366         char *str;
 367
 368         if (!cmd->argv)
 369                 cmd->argv = cmd->args.argv;
 370         if (!cmd->env)
 371                 cmd->env = cmd->env_array.argv;
 372
 373         /*
 374          * In case of errors we must keep the promise to close FDs
 375          * that have been passed in via ->in and ->out.
 376          */
 377
 378         need_in = !cmd->no_stdin && cmd->in < 0;
 379         if (need_in) {
 380                 if (pipe(fdin) < 0) {
 381                         failed_errno = errno;
 382                         if (cmd->out > 0)
 383                                 close(cmd->out);
 384                         str = "standard input";
 385                         goto fail_pipe;
 386                 }
 387                 cmd->in = fdin[1];
 388         }
 389
 390         need_out = !cmd->no_stdout
 391                 && !cmd->stdout_to_stderr
 392                 && cmd->out < 0;
 393         if (need_out) {
 394                 if (pipe(fdout) < 0) {
 395                         failed_errno = errno;
 396                         if (need_in)
 397                                 close_pair(fdin);
 398                         else if (cmd->in)
 399                                 close(cmd->in);
 400                         str = "standard output";
 401                         goto fail_pipe;
 402                 }
 403                 cmd->out = fdout[0];
 404         }
 405
 406         need_err = !cmd->no_stderr && cmd->err < 0;
 407         if (need_err) {
 408                 if (pipe(fderr) < 0) {
 409                         failed_errno = errno;
 410                         if (need_in)
 411                                 close_pair(fdin);
 412                         else if (cmd->in)
 413                                 close(cmd->in);
 414                         if (need_out)
 415                                 close_pair(fdout);
 416                         else if (cmd->out)
 417                                 close(cmd->out);
 418                         str = "standard error";
 419 fail_pipe:
 420                         error("cannot create %s pipe for %s: %s",
 421                                 str, cmd->argv[0], strerror(failed_errno));
 422                         child_process_clear(cmd);
 423                         errno = failed_errno;
 424                         return -1;
 425                 }
 426                 cmd->err = fderr[0];
 427         }
 428
 429         trace_argv_printf(cmd->argv, "trace: run_command:");
 430         fflush(NULL);
 431
 432 #ifndef GIT_WINDOWS_NATIVE
 433 {
 434         int notify_pipe[2];
 435         int null_fd = -1;
 436         char **childenv;
 437         struct argv_array argv = ARGV_ARRAY_INIT;
 438
 439         if (pipe(notify_pipe))
 440                 notify_pipe[0] = notify_pipe[1] = -1;
 441
 442         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 443                 null_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
 444                 if (null_fd < 0)
 445                         die_errno(_("open /dev/null failed"));
 446                 set_cloexec(null_fd);
 447         }
 448
 449         prepare_cmd(&argv, cmd);
 450         childenv = prep_childenv(cmd->env);
 451
 452         cmd->pid = fork();
 453         failed_errno = errno;
 454         if (!cmd->pid) {
 455                 /*
 456                  * Redirect the channel to write syscall error messages to
 457                  * before redirecting the process's stderr so that all die()
 458                  * in subsequent call paths use the parent's stderr.
 459                  */
 460                 if (cmd->no_stderr || need_err) {
 461                         int child_err = dup(2);
 462                         set_cloexec(child_err);
 463                         set_error_handle(fdopen(child_err, "w"));
 464                 }
 465
 466                 close(notify_pipe[0]);
 467                 set_cloexec(notify_pipe[1]);
 468                 child_notifier = notify_pipe[1];
 469                 atexit(notify_parent);
 470
 471                 if (cmd->no_stdin)
 472                         dup2(null_fd, 0);
 473                 else if (need_in) {
 474                         dup2(fdin[0], 0);
 475                         close_pair(fdin);
 476                 } else if (cmd->in) {
 477                         dup2(cmd->in, 0);
 478                         close(cmd->in);
 479                 }
 480
 481                 if (cmd->no_stderr)
 482                         dup2(null_fd, 2);
 483                 else if (need_err) {
 484                         dup2(fderr[1], 2);
 485                         close_pair(fderr);
 486                 } else if (cmd->err > 1) {
 487                         dup2(cmd->err, 2);
 488                         close(cmd->err);
 489                 }
 490
 491                 if (cmd->no_stdout)
 492                         dup2(null_fd, 1);
 493                 else if (cmd->stdout_to_stderr)
 494                         dup2(2, 1);
 495                 else if (need_out) {
 496                         dup2(fdout[1], 1);
 497                         close_pair(fdout);
 498                 } else if (cmd->out > 1) {
 499                         dup2(cmd->out, 1);
 500                         close(cmd->out);
 501                 }
 502
 503                 if (cmd->dir && chdir(cmd->dir))
 504                         die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 505                             cmd->dir);
 506
 507                 /*
 508                  * Attempt to exec using the command and arguments starting at
 509                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 510                  * be used in the event exec failed with ENOEXEC at which point
 511                  * we will try to interpret the command using 'sh'.
 512                  */
 513                 execve(argv.argv[1], (char *const *) argv.argv + 1,
 514                        (char *const *) childenv);
 515                 if (errno == ENOEXEC)
 516                         execve(argv.argv[0], (char *const *) argv.argv,
 517                                (char *const *) childenv);
 518
 519                 if (errno == ENOENT) {
 520                         if (!cmd->silent_exec_failure)
 521                                 error("cannot run %s: %s", cmd->argv[0],
 522                                         strerror(ENOENT));
 523                         exit(127);
 524                 } else {
 525                         die_errno("cannot exec '%s'", cmd->argv[0]);
 526                 }
 527         }
 528         if (cmd->pid < 0)
 529                 error_errno("cannot fork() for %s", cmd->argv[0]);
 530         else if (cmd->clean_on_exit)
 531                 mark_child_for_cleanup(cmd->pid, cmd);
 532
 533         /*
 534          * Wait for child's exec. If the exec succeeds (or if fork()
 535          * failed), EOF is seen immediately by the parent. Otherwise, the
 536          * child process sends a single byte.
 537          * Note that use of this infrastructure is completely advisory,
 538          * therefore, we keep error checks minimal.
 539          */
 540         close(notify_pipe[1]);
 541         if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 542                 /*
 543                  * At this point we know that fork() succeeded, but exec()
 544                  * failed. Errors have been reported to our stderr.
 545                  */
 546                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 547                 failed_errno = errno;
 548                 cmd->pid = -1;
 549         }
 550         close(notify_pipe[0]);
 551
 552         if (null_fd >= 0)
 553                 close(null_fd);
 554         argv_array_clear(&argv);
 555         free(childenv);
 556 }
 557 #else
 558 {
 559         int fhin = 0, fhout = 1, fherr = 2;
 560         const char **sargv = cmd->argv;
 561         struct argv_array nargv = ARGV_ARRAY_INIT;
 562
 563         if (cmd->no_stdin)
 564                 fhin = open("/dev/null", O_RDWR);
 565         else if (need_in)
 566                 fhin = dup(fdin[0]);
 567         else if (cmd->in)
 568                 fhin = dup(cmd->in);
 569
 570         if (cmd->no_stderr)
 571                 fherr = open("/dev/null", O_RDWR);
 572         else if (need_err)
 573                 fherr = dup(fderr[1]);
 574         else if (cmd->err > 2)
 575                 fherr = dup(cmd->err);
 576
 577         if (cmd->no_stdout)
 578                 fhout = open("/dev/null", O_RDWR);
 579         else if (cmd->stdout_to_stderr)
 580                 fhout = dup(fherr);
 581         else if (need_out)
 582                 fhout = dup(fdout[1]);
 583         else if (cmd->out > 1)
 584                 fhout = dup(cmd->out);
 585
 586         if (cmd->git_cmd)
 587                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 588         else if (cmd->use_shell)
 589                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 590
 591         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 592                         cmd->dir, fhin, fhout, fherr);
 593         failed_errno = errno;
 594         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 595                 error_errno("cannot spawn %s", cmd->argv[0]);
 596         if (cmd->clean_on_exit && cmd->pid >= 0)
 597                 mark_child_for_cleanup(cmd->pid, cmd);
 598
 599         argv_array_clear(&nargv);
 600         cmd->argv = sargv;
 601         if (fhin != 0)
 602                 close(fhin);
 603         if (fhout != 1)
 604                 close(fhout);
 605         if (fherr != 2)
 606                 close(fherr);
 607 }
 608 #endif
 609
 610         if (cmd->pid < 0) {
 611                 if (need_in)
 612                         close_pair(fdin);
 613                 else if (cmd->in)
 614                         close(cmd->in);
 615                 if (need_out)
 616                         close_pair(fdout);
 617                 else if (cmd->out)
 618                         close(cmd->out);
 619                 if (need_err)
 620                         close_pair(fderr);
 621                 else if (cmd->err)
 622                         close(cmd->err);
 623                 child_process_clear(cmd);
 624                 errno = failed_errno;
 625                 return -1;
 626         }
 627
 628         if (need_in)
 629                 close(fdin[0]);
 630         else if (cmd->in)
 631                 close(cmd->in);
 632
 633         if (need_out)
 634                 close(fdout[1]);
 635         else if (cmd->out)
 636                 close(cmd->out);
 637
 638         if (need_err)
 639                 close(fderr[1]);
 640         else if (cmd->err)
 641                 close(cmd->err);
 642
 643         return 0;
 644 }
 645
 646 int finish_command(struct child_process *cmd)
 647 {
 648         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 649         child_process_clear(cmd);
 650         return ret;
 651 }
 652
 653 int finish_command_in_signal(struct child_process *cmd)
 654 {
 655         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 656 }
 657
 658
 659 int run_command(struct child_process *cmd)
 660 {
 661         int code;
 662
 663         if (cmd->out < 0 || cmd->err < 0)
 664                 die("BUG: run_command with a pipe can cause deadlock");
 665
 666         code = start_command(cmd);
 667         if (code)
 668                 return code;
 669         return finish_command(cmd);
 670 }
 671
 672 int run_command_v_opt(const char **argv, int opt)
 673 {
 674         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 675 }
 676
 677 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 678 {
 679         struct child_process cmd = CHILD_PROCESS_INIT;
 680         cmd.argv = argv;
 681         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 682         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 683         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 684         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 685         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 686         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 687         cmd.dir = dir;
 688         cmd.env = env;
 689         return run_command(&cmd);
 690 }
 691
 692 #ifndef NO_PTHREADS
 693 static pthread_t main_thread;
 694 static int main_thread_set;
 695 static pthread_key_t async_key;
 696 static pthread_key_t async_die_counter;
 697
 698 static void *run_thread(void *data)
 699 {
 700         struct async *async = data;
 701         intptr_t ret;
 702
 703         if (async->isolate_sigpipe) {
 704                 sigset_t mask;
 705                 sigemptyset(&mask);
 706                 sigaddset(&mask, SIGPIPE);
 707                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 708                         ret = error("unable to block SIGPIPE in async thread");
 709                         return (void *)ret;
 710                 }
 711         }
 712
 713         pthread_setspecific(async_key, async);
 714         ret = async->proc(async->proc_in, async->proc_out, async->data);
 715         return (void *)ret;
 716 }
 717
 718 static NORETURN void die_async(const char *err, va_list params)
 719 {
 720         vreportf("fatal: ", err, params);
 721
 722         if (in_async()) {
 723                 struct async *async = pthread_getspecific(async_key);
 724                 if (async->proc_in >= 0)
 725                         close(async->proc_in);
 726                 if (async->proc_out >= 0)
 727                         close(async->proc_out);
 728                 pthread_exit((void *)128);
 729         }
 730
 731         exit(128);
 732 }
 733
 734 static int async_die_is_recursing(void)
 735 {
 736         void *ret = pthread_getspecific(async_die_counter);
 737         pthread_setspecific(async_die_counter, (void *)1);
 738         return ret != NULL;
 739 }
 740
 741 int in_async(void)
 742 {
 743         if (!main_thread_set)
 744                 return 0; /* no asyncs started yet */
 745         return !pthread_equal(main_thread, pthread_self());
 746 }
 747
 748 static void NORETURN async_exit(int code)
 749 {
 750         pthread_exit((void *)(intptr_t)code);
 751 }
 752
 753 #else
 754
 755 static struct {
 756         void (**handlers)(void);
 757         size_t nr;
 758         size_t alloc;
 759 } git_atexit_hdlrs;
 760
 761 static int git_atexit_installed;
 762
 763 static void git_atexit_dispatch(void)
 764 {
 765         size_t i;
 766
 767         for (i=git_atexit_hdlrs.nr ; i ; i--)
 768                 git_atexit_hdlrs.handlers[i-1]();
 769 }
 770
 771 static void git_atexit_clear(void)
 772 {
 773         free(git_atexit_hdlrs.handlers);
 774         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 775         git_atexit_installed = 0;
 776 }
 777
 778 #undef atexit
 779 int git_atexit(void (*handler)(void))
 780 {
 781         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 782         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 783         if (!git_atexit_installed) {
 784                 if (atexit(&git_atexit_dispatch))
 785                         return -1;
 786                 git_atexit_installed = 1;
 787         }
 788         return 0;
 789 }
 790 #define atexit git_atexit
 791
 792 static int process_is_async;
 793 int in_async(void)
 794 {
 795         return process_is_async;
 796 }
 797
 798 static void NORETURN async_exit(int code)
 799 {
 800         exit(code);
 801 }
 802
 803 #endif
 804
 805 void check_pipe(int err)
 806 {
 807         if (err == EPIPE) {
 808                 if (in_async())
 809                         async_exit(141);
 810
 811                 signal(SIGPIPE, SIG_DFL);
 812                 raise(SIGPIPE);
 813                 /* Should never happen, but just in case... */
 814                 exit(141);
 815         }
 816 }
 817
 818 int start_async(struct async *async)
 819 {
 820         int need_in, need_out;
 821         int fdin[2], fdout[2];
 822         int proc_in, proc_out;
 823
 824         need_in = async->in < 0;
 825         if (need_in) {
 826                 if (pipe(fdin) < 0) {
 827                         if (async->out > 0)
 828                                 close(async->out);
 829                         return error_errno("cannot create pipe");
 830                 }
 831                 async->in = fdin[1];
 832         }
 833
 834         need_out = async->out < 0;
 835         if (need_out) {
 836                 if (pipe(fdout) < 0) {
 837                         if (need_in)
 838                                 close_pair(fdin);
 839                         else if (async->in)
 840                                 close(async->in);
 841                         return error_errno("cannot create pipe");
 842                 }
 843                 async->out = fdout[0];
 844         }
 845
 846         if (need_in)
 847                 proc_in = fdin[0];
 848         else if (async->in)
 849                 proc_in = async->in;
 850         else
 851                 proc_in = -1;
 852
 853         if (need_out)
 854                 proc_out = fdout[1];
 855         else if (async->out)
 856                 proc_out = async->out;
 857         else
 858                 proc_out = -1;
 859
 860 #ifdef NO_PTHREADS
 861         /* Flush stdio before fork() to avoid cloning buffers */
 862         fflush(NULL);
 863
 864         async->pid = fork();
 865         if (async->pid < 0) {
 866                 error_errno("fork (async) failed");
 867                 goto error;
 868         }
 869         if (!async->pid) {
 870                 if (need_in)
 871                         close(fdin[1]);
 872                 if (need_out)
 873                         close(fdout[0]);
 874                 git_atexit_clear();
 875                 process_is_async = 1;
 876                 exit(!!async->proc(proc_in, proc_out, async->data));
 877         }
 878
 879         mark_child_for_cleanup(async->pid, NULL);
 880
 881         if (need_in)
 882                 close(fdin[0]);
 883         else if (async->in)
 884                 close(async->in);
 885
 886         if (need_out)
 887                 close(fdout[1]);
 888         else if (async->out)
 889                 close(async->out);
 890 #else
 891         if (!main_thread_set) {
 892                 /*
 893                  * We assume that the first time that start_async is called
 894                  * it is from the main thread.
 895                  */
 896                 main_thread_set = 1;
 897                 main_thread = pthread_self();
 898                 pthread_key_create(&async_key, NULL);
 899                 pthread_key_create(&async_die_counter, NULL);
 900                 set_die_routine(die_async);
 901                 set_die_is_recursing_routine(async_die_is_recursing);
 902         }
 903
 904         if (proc_in >= 0)
 905                 set_cloexec(proc_in);
 906         if (proc_out >= 0)
 907                 set_cloexec(proc_out);
 908         async->proc_in = proc_in;
 909         async->proc_out = proc_out;
 910         {
 911                 int err = pthread_create(&async->tid, NULL, run_thread, async);
 912                 if (err) {
 913                         error_errno("cannot create thread");
 914                         goto error;
 915                 }
 916         }
 917 #endif
 918         return 0;
 919
 920 error:
 921         if (need_in)
 922                 close_pair(fdin);
 923         else if (async->in)
 924                 close(async->in);
 925
 926         if (need_out)
 927                 close_pair(fdout);
 928         else if (async->out)
 929                 close(async->out);
 930         return -1;
 931 }
 932
 933 int finish_async(struct async *async)
 934 {
 935 #ifdef NO_PTHREADS
 936         return wait_or_whine(async->pid, "child process", 0);
 937 #else
 938         void *ret = (void *)(intptr_t)(-1);
 939
 940         if (pthread_join(async->tid, &ret))
 941                 error("pthread_join failed");
 942         return (int)(intptr_t)ret;
 943 #endif
 944 }
 945
 946 const char *find_hook(const char *name)
 947 {
 948         static struct strbuf path = STRBUF_INIT;
 949
 950         strbuf_reset(&path);
 951         strbuf_git_path(&path, "hooks/%s", name);
 952         if (access(path.buf, X_OK) < 0) {
 953 #ifdef STRIP_EXTENSION
 954                 strbuf_addstr(&path, STRIP_EXTENSION);
 955                 if (access(path.buf, X_OK) >= 0)
 956                         return path.buf;
 957 #endif
 958                 return NULL;
 959         }
 960         return path.buf;
 961 }
 962
 963 int run_hook_ve(const char *const *env, const char *name, va_list args)
 964 {
 965         struct child_process hook = CHILD_PROCESS_INIT;
 966         const char *p;
 967
 968         p = find_hook(name);
 969         if (!p)
 970                 return 0;
 971
 972         argv_array_push(&hook.args, p);
 973         while ((p = va_arg(args, const char *)))
 974                 argv_array_push(&hook.args, p);
 975         hook.env = env;
 976         hook.no_stdin = 1;
 977         hook.stdout_to_stderr = 1;
 978
 979         return run_command(&hook);
 980 }
 981
 982 int run_hook_le(const char *const *env, const char *name, ...)
 983 {
 984         va_list args;
 985         int ret;
 986
 987         va_start(args, name);
 988         ret = run_hook_ve(env, name, args);
 989         va_end(args);
 990
 991         return ret;
 992 }
 993
 994 struct io_pump {
 995         /* initialized by caller */
 996         int fd;
 997         int type; /* POLLOUT or POLLIN */
 998         union {
 999                 struct {
1000                         const char *buf;
1001                         size_t len;
1002                 } out;
1003                 struct {
1004                         struct strbuf *buf;
1005                         size_t hint;
1006                 } in;
1007         } u;
1008
1009         /* returned by pump_io */
1010         int error; /* 0 for success, otherwise errno */
1011
1012         /* internal use */
1013         struct pollfd *pfd;
1014 };
1015
1016 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1017 {
1018         int pollsize = 0;
1019         int i;
1020
1021         for (i = 0; i < nr; i++) {
1022                 struct io_pump *io = &slots[i];
1023                 if (io->fd < 0)
1024                         continue;
1025                 pfd[pollsize].fd = io->fd;
1026                 pfd[pollsize].events = io->type;
1027                 io->pfd = &pfd[pollsize++];
1028         }
1029
1030         if (!pollsize)
1031                 return 0;
1032
1033         if (poll(pfd, pollsize, -1) < 0) {
1034                 if (errno == EINTR)
1035                         return 1;
1036                 die_errno("poll failed");
1037         }
1038
1039         for (i = 0; i < nr; i++) {
1040                 struct io_pump *io = &slots[i];
1041
1042                 if (io->fd < 0)
1043                         continue;
1044
1045                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1046                         continue;
1047
1048                 if (io->type == POLLOUT) {
1049                         ssize_t len = xwrite(io->fd,
1050                                              io->u.out.buf, io->u.out.len);
1051                         if (len < 0) {
1052                                 io->error = errno;
1053                                 close(io->fd);
1054                                 io->fd = -1;
1055                         } else {
1056                                 io->u.out.buf += len;
1057                                 io->u.out.len -= len;
1058                                 if (!io->u.out.len) {
1059                                         close(io->fd);
1060                                         io->fd = -1;
1061                                 }
1062                         }
1063                 }
1064
1065                 if (io->type == POLLIN) {
1066                         ssize_t len = strbuf_read_once(io->u.in.buf,
1067                                                        io->fd, io->u.in.hint);
1068                         if (len < 0)
1069                                 io->error = errno;
1070                         if (len <= 0) {
1071                                 close(io->fd);
1072                                 io->fd = -1;
1073                         }
1074                 }
1075         }
1076
1077         return 1;
1078 }
1079
1080 static int pump_io(struct io_pump *slots, int nr)
1081 {
1082         struct pollfd *pfd;
1083         int i;
1084
1085         for (i = 0; i < nr; i++)
1086                 slots[i].error = 0;
1087
1088         ALLOC_ARRAY(pfd, nr);
1089         while (pump_io_round(slots, nr, pfd))
1090                 ; /* nothing */
1091         free(pfd);
1092
1093         /* There may be multiple errno values, so just pick the first. */
1094         for (i = 0; i < nr; i++) {
1095                 if (slots[i].error) {
1096                         errno = slots[i].error;
1097                         return -1;
1098                 }
1099         }
1100         return 0;
1101 }
1102
1103
1104 int pipe_command(struct child_process *cmd,
1105                  const char *in, size_t in_len,
1106                  struct strbuf *out, size_t out_hint,
1107                  struct strbuf *err, size_t err_hint)
1108 {
1109         struct io_pump io[3];
1110         int nr = 0;
1111
1112         if (in)
1113                 cmd->in = -1;
1114         if (out)
1115                 cmd->out = -1;
1116         if (err)
1117                 cmd->err = -1;
1118
1119         if (start_command(cmd) < 0)
1120                 return -1;
1121
1122         if (in) {
1123                 io[nr].fd = cmd->in;
1124                 io[nr].type = POLLOUT;
1125                 io[nr].u.out.buf = in;
1126                 io[nr].u.out.len = in_len;
1127                 nr++;
1128         }
1129         if (out) {
1130                 io[nr].fd = cmd->out;
1131                 io[nr].type = POLLIN;
1132                 io[nr].u.in.buf = out;
1133                 io[nr].u.in.hint = out_hint;
1134                 nr++;
1135         }
1136         if (err) {
1137                 io[nr].fd = cmd->err;
1138                 io[nr].type = POLLIN;
1139                 io[nr].u.in.buf = err;
1140                 io[nr].u.in.hint = err_hint;
1141                 nr++;
1142         }
1143
1144         if (pump_io(io, nr) < 0) {
1145                 finish_command(cmd); /* throw away exit code */
1146                 return -1;
1147         }
1148
1149         return finish_command(cmd);
1150 }
1151
1152 enum child_state {
1153         GIT_CP_FREE,
1154         GIT_CP_WORKING,
1155         GIT_CP_WAIT_CLEANUP,
1156 };
1157
1158 struct parallel_processes {
1159         void *data;
1160
1161         int max_processes;
1162         int nr_processes;
1163
1164         get_next_task_fn get_next_task;
1165         start_failure_fn start_failure;
1166         task_finished_fn task_finished;
1167
1168         struct {
1169                 enum child_state state;
1170                 struct child_process process;
1171                 struct strbuf err;
1172                 void *data;
1173         } *children;
1174         /*
1175          * The struct pollfd is logically part of *children,
1176          * but the system call expects it as its own array.
1177          */
1178         struct pollfd *pfd;
1179
1180         unsigned shutdown : 1;
1181
1182         int output_owner;
1183         struct strbuf buffered_output; /* of finished children */
1184 };
1185
1186 static int default_start_failure(struct strbuf *out,
1187                                  void *pp_cb,
1188                                  void *pp_task_cb)
1189 {
1190         return 0;
1191 }
1192
1193 static int default_task_finished(int result,
1194                                  struct strbuf *out,
1195                                  void *pp_cb,
1196                                  void *pp_task_cb)
1197 {
1198         return 0;
1199 }
1200
1201 static void kill_children(struct parallel_processes *pp, int signo)
1202 {
1203         int i, n = pp->max_processes;
1204
1205         for (i = 0; i < n; i++)
1206                 if (pp->children[i].state == GIT_CP_WORKING)
1207                         kill(pp->children[i].process.pid, signo);
1208 }
1209
1210 static struct parallel_processes *pp_for_signal;
1211
1212 static void handle_children_on_signal(int signo)
1213 {
1214         kill_children(pp_for_signal, signo);
1215         sigchain_pop(signo);
1216         raise(signo);
1217 }
1218
1219 static void pp_init(struct parallel_processes *pp,
1220                     int n,
1221                     get_next_task_fn get_next_task,
1222                     start_failure_fn start_failure,
1223                     task_finished_fn task_finished,
1224                     void *data)
1225 {
1226         int i;
1227
1228         if (n < 1)
1229                 n = online_cpus();
1230
1231         pp->max_processes = n;
1232
1233         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1234
1235         pp->data = data;
1236         if (!get_next_task)
1237                 die("BUG: you need to specify a get_next_task function");
1238         pp->get_next_task = get_next_task;
1239
1240         pp->start_failure = start_failure ? start_failure : default_start_failure;
1241         pp->task_finished = task_finished ? task_finished : default_task_finished;
1242
1243         pp->nr_processes = 0;
1244         pp->output_owner = 0;
1245         pp->shutdown = 0;
1246         pp->children = xcalloc(n, sizeof(*pp->children));
1247         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1248         strbuf_init(&pp->buffered_output, 0);
1249
1250         for (i = 0; i < n; i++) {
1251                 strbuf_init(&pp->children[i].err, 0);
1252                 child_process_init(&pp->children[i].process);
1253                 pp->pfd[i].events = POLLIN | POLLHUP;
1254                 pp->pfd[i].fd = -1;
1255         }
1256
1257         pp_for_signal = pp;
1258         sigchain_push_common(handle_children_on_signal);
1259 }
1260
1261 static void pp_cleanup(struct parallel_processes *pp)
1262 {
1263         int i;
1264
1265         trace_printf("run_processes_parallel: done");
1266         for (i = 0; i < pp->max_processes; i++) {
1267                 strbuf_release(&pp->children[i].err);
1268                 child_process_clear(&pp->children[i].process);
1269         }
1270
1271         free(pp->children);
1272         free(pp->pfd);
1273
1274         /*
1275          * When get_next_task added messages to the buffer in its last
1276          * iteration, the buffered output is non empty.
1277          */
1278         strbuf_write(&pp->buffered_output, stderr);
1279         strbuf_release(&pp->buffered_output);
1280
1281         sigchain_pop_common();
1282 }
1283
1284 /* returns
1285  *  0 if a new task was started.
1286  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1287  *    problem with starting a new command)
1288  * <0 no new job was started, user wishes to shutdown early. Use negative code
1289  *    to signal the children.
1290  */
1291 static int pp_start_one(struct parallel_processes *pp)
1292 {
1293         int i, code;
1294
1295         for (i = 0; i < pp->max_processes; i++)
1296                 if (pp->children[i].state == GIT_CP_FREE)
1297                         break;
1298         if (i == pp->max_processes)
1299                 die("BUG: bookkeeping is hard");
1300
1301         code = pp->get_next_task(&pp->children[i].process,
1302                                  &pp->children[i].err,
1303                                  pp->data,
1304                                  &pp->children[i].data);
1305         if (!code) {
1306                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1307                 strbuf_reset(&pp->children[i].err);
1308                 return 1;
1309         }
1310         pp->children[i].process.err = -1;
1311         pp->children[i].process.stdout_to_stderr = 1;
1312         pp->children[i].process.no_stdin = 1;
1313
1314         if (start_command(&pp->children[i].process)) {
1315                 code = pp->start_failure(&pp->children[i].err,
1316                                          pp->data,
1317                                          &pp->children[i].data);
1318                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1319                 strbuf_reset(&pp->children[i].err);
1320                 if (code)
1321                         pp->shutdown = 1;
1322                 return code;
1323         }
1324
1325         pp->nr_processes++;
1326         pp->children[i].state = GIT_CP_WORKING;
1327         pp->pfd[i].fd = pp->children[i].process.err;
1328         return 0;
1329 }
1330
1331 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1332 {
1333         int i;
1334
1335         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1336                 if (errno == EINTR)
1337                         continue;
1338                 pp_cleanup(pp);
1339                 die_errno("poll");
1340         }
1341
1342         /* Buffer output from all pipes. */
1343         for (i = 0; i < pp->max_processes; i++) {
1344                 if (pp->children[i].state == GIT_CP_WORKING &&
1345                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1346                         int n = strbuf_read_once(&pp->children[i].err,
1347                                                  pp->children[i].process.err, 0);
1348                         if (n == 0) {
1349                                 close(pp->children[i].process.err);
1350                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1351                         } else if (n < 0)
1352                                 if (errno != EAGAIN)
1353                                         die_errno("read");
1354                 }
1355         }
1356 }
1357
1358 static void pp_output(struct parallel_processes *pp)
1359 {
1360         int i = pp->output_owner;
1361         if (pp->children[i].state == GIT_CP_WORKING &&
1362             pp->children[i].err.len) {
1363                 strbuf_write(&pp->children[i].err, stderr);
1364                 strbuf_reset(&pp->children[i].err);
1365         }
1366 }
1367
1368 static int pp_collect_finished(struct parallel_processes *pp)
1369 {
1370         int i, code;
1371         int n = pp->max_processes;
1372         int result = 0;
1373
1374         while (pp->nr_processes > 0) {
1375                 for (i = 0; i < pp->max_processes; i++)
1376                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1377                                 break;
1378                 if (i == pp->max_processes)
1379                         break;
1380
1381                 code = finish_command(&pp->children[i].process);
1382
1383                 code = pp->task_finished(code,
1384                                          &pp->children[i].err, pp->data,
1385                                          &pp->children[i].data);
1386
1387                 if (code)
1388                         result = code;
1389                 if (code < 0)
1390                         break;
1391
1392                 pp->nr_processes--;
1393                 pp->children[i].state = GIT_CP_FREE;
1394                 pp->pfd[i].fd = -1;
1395                 child_process_init(&pp->children[i].process);
1396
1397                 if (i != pp->output_owner) {
1398                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1399                         strbuf_reset(&pp->children[i].err);
1400                 } else {
1401                         strbuf_write(&pp->children[i].err, stderr);
1402                         strbuf_reset(&pp->children[i].err);
1403
1404                         /* Output all other finished child processes */
1405                         strbuf_write(&pp->buffered_output, stderr);
1406                         strbuf_reset(&pp->buffered_output);
1407
1408                         /*
1409                          * Pick next process to output live.
1410                          * NEEDSWORK:
1411                          * For now we pick it randomly by doing a round
1412                          * robin. Later we may want to pick the one with
1413                          * the most output or the longest or shortest
1414                          * running process time.
1415                          */
1416                         for (i = 0; i < n; i++)
1417                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1418                                         break;
1419                         pp->output_owner = (pp->output_owner + i) % n;
1420                 }
1421         }
1422         return result;
1423 }
1424
1425 int run_processes_parallel(int n,
1426                            get_next_task_fn get_next_task,
1427                            start_failure_fn start_failure,
1428                            task_finished_fn task_finished,
1429                            void *pp_cb)
1430 {
1431         int i, code;
1432         int output_timeout = 100;
1433         int spawn_cap = 4;
1434         struct parallel_processes pp;
1435
1436         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1437         while (1) {
1438                 for (i = 0;
1439                     i < spawn_cap && !pp.shutdown &&
1440                     pp.nr_processes < pp.max_processes;
1441                     i++) {
1442                         code = pp_start_one(&pp);
1443                         if (!code)
1444                                 continue;
1445                         if (code < 0) {
1446                                 pp.shutdown = 1;
1447                                 kill_children(&pp, -code);
1448                         }
1449                         break;
1450                 }
1451                 if (!pp.nr_processes)
1452                         break;
1453                 pp_buffer_stderr(&pp, output_timeout);
1454                 pp_output(&pp);
1455                 code = pp_collect_finished(&pp);
1456                 if (code) {
1457                         pp.shutdown = 1;
1458                         if (code < 0)
1459                                 kill_children(&pp, -code);
1460                 }
1461         }
1462
1463         pp_cleanup(&pp);
1464         return 0;
1465 }