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 #ifndef GIT_WINDOWS_NATIVE
 121 static inline void dup_devnull(int to)
 122 {
 123         int fd = open("/dev/null", O_RDWR);
 124         if (fd < 0)
 125                 die_errno(_("open /dev/null failed"));
 126         if (dup2(fd, to) < 0)
 127                 die_errno(_("dup2(%d,%d) failed"), fd, to);
 128         close(fd);
 129 }
 130 #endif
 131
 132 static char *locate_in_PATH(const char *file)
 133 {
 134         const char *p = getenv("PATH");
 135         struct strbuf buf = STRBUF_INIT;
 136
 137         if (!p || !*p)
 138                 return NULL;
 139
 140         while (1) {
 141                 const char *end = strchrnul(p, ':');
 142
 143                 strbuf_reset(&buf);
 144
 145                 /* POSIX specifies an empty entry as the current directory. */
 146                 if (end != p) {
 147                         strbuf_add(&buf, p, end - p);
 148                         strbuf_addch(&buf, '/');
 149                 }
 150                 strbuf_addstr(&buf, file);
 151
 152                 if (!access(buf.buf, F_OK))
 153                         return strbuf_detach(&buf, NULL);
 154
 155                 if (!*end)
 156                         break;
 157                 p = end + 1;
 158         }
 159
 160         strbuf_release(&buf);
 161         return NULL;
 162 }
 163
 164 static int exists_in_PATH(const char *file)
 165 {
 166         char *r = locate_in_PATH(file);
 167         free(r);
 168         return r != NULL;
 169 }
 170
 171 int sane_execvp(const char *file, char * const argv[])
 172 {
 173         if (!execvp(file, argv))
 174                 return 0; /* cannot happen ;-) */
 175
 176         /*
 177          * When a command can't be found because one of the directories
 178          * listed in $PATH is unsearchable, execvp reports EACCES, but
 179          * careful usability testing (read: analysis of occasional bug
 180          * reports) reveals that "No such file or directory" is more
 181          * intuitive.
 182          *
 183          * We avoid commands with "/", because execvp will not do $PATH
 184          * lookups in that case.
 185          *
 186          * The reassignment of EACCES to errno looks like a no-op below,
 187          * but we need to protect against exists_in_PATH overwriting errno.
 188          */
 189         if (errno == EACCES && !strchr(file, '/'))
 190                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 191         else if (errno == ENOTDIR && !strchr(file, '/'))
 192                 errno = ENOENT;
 193         return -1;
 194 }
 195
 196 static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 197 {
 198         if (!argv[0])
 199                 die("BUG: shell command is empty");
 200
 201         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 202 #ifndef GIT_WINDOWS_NATIVE
 203                 argv_array_push(out, SHELL_PATH);
 204 #else
 205                 argv_array_push(out, "sh");
 206 #endif
 207                 argv_array_push(out, "-c");
 208
 209                 /*
 210                  * If we have no extra arguments, we do not even need to
 211                  * bother with the "$@" magic.
 212                  */
 213                 if (!argv[1])
 214                         argv_array_push(out, argv[0]);
 215                 else
 216                         argv_array_pushf(out, "%s \"$@\"", argv[0]);
 217         }
 218
 219         argv_array_pushv(out, argv);
 220         return out->argv;
 221 }
 222
 223 #ifndef GIT_WINDOWS_NATIVE
 224 static int child_notifier = -1;
 225
 226 static void notify_parent(void)
 227 {
 228         /*
 229          * execvp failed.  If possible, we'd like to let start_command
 230          * know, so failures like ENOENT can be handled right away; but
 231          * otherwise, finish_command will still report the error.
 232          */
 233         xwrite(child_notifier, "", 1);
 234 }
 235
 236 static void prepare_cmd(struct argv_array *out, const struct child_process *cmd)
 237 {
 238         if (!cmd->argv[0])
 239                 die("BUG: command is empty");
 240
 241         /*
 242          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 243          * attempt to interpret the command with 'sh'.
 244          */
 245         argv_array_push(out, SHELL_PATH);
 246
 247         if (cmd->git_cmd) {
 248                 argv_array_push(out, "git");
 249                 argv_array_pushv(out, cmd->argv);
 250         } else if (cmd->use_shell) {
 251                 prepare_shell_cmd(out, cmd->argv);
 252         } else {
 253                 argv_array_pushv(out, cmd->argv);
 254         }
 255
 256         /*
 257          * If there are no '/' characters in the command then perform a path
 258          * lookup and use the resolved path as the command to exec.  If there
 259          * are no '/' characters or if the command wasn't found in the path,
 260          * have exec attempt to invoke the command directly.
 261          */
 262         if (!strchr(out->argv[1], '/')) {
 263                 char *program = locate_in_PATH(out->argv[1]);
 264                 if (program) {
 265                         free((char *)out->argv[1]);
 266                         out->argv[1] = program;
 267                 }
 268         }
 269 }
 270
 271 static char **prep_childenv(const char *const *deltaenv)
 272 {
 273         extern char **environ;
 274         char **childenv;
 275         struct string_list env = STRING_LIST_INIT_DUP;
 276         struct strbuf key = STRBUF_INIT;
 277         const char *const *p;
 278         int i;
 279
 280         /* Construct a sorted string list consisting of the current environ */
 281         for (p = (const char *const *) environ; p && *p; p++) {
 282                 const char *equals = strchr(*p, '=');
 283
 284                 if (equals) {
 285                         strbuf_reset(&key);
 286                         strbuf_add(&key, *p, equals - *p);
 287                         string_list_append(&env, key.buf)->util = (void *) *p;
 288                 } else {
 289                         string_list_append(&env, *p)->util = (void *) *p;
 290                 }
 291         }
 292         string_list_sort(&env);
 293
 294         /* Merge in 'deltaenv' with the current environ */
 295         for (p = deltaenv; p && *p; p++) {
 296                 const char *equals = strchr(*p, '=');
 297
 298                 if (equals) {
 299                         /* ('key=value'), insert or replace entry */
 300                         strbuf_reset(&key);
 301                         strbuf_add(&key, *p, equals - *p);
 302                         string_list_insert(&env, key.buf)->util = (void *) *p;
 303                 } else {
 304                         /* otherwise ('key') remove existing entry */
 305                         string_list_remove(&env, *p, 0);
 306                 }
 307         }
 308
 309         /* Create an array of 'char *' to be used as the childenv */
 310         childenv = xmalloc((env.nr + 1) * sizeof(char *));
 311         for (i = 0; i < env.nr; i++)
 312                 childenv[i] = env.items[i].util;
 313         childenv[env.nr] = NULL;
 314
 315         string_list_clear(&env, 0);
 316         strbuf_release(&key);
 317         return childenv;
 318 }
 319 #endif
 320
 321 static inline void set_cloexec(int fd)
 322 {
 323         int flags = fcntl(fd, F_GETFD);
 324         if (flags >= 0)
 325                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 326 }
 327
 328 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 329 {
 330         int status, code = -1;
 331         pid_t waiting;
 332         int failed_errno = 0;
 333
 334         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 335                 ;       /* nothing */
 336         if (in_signal)
 337                 return 0;
 338
 339         if (waiting < 0) {
 340                 failed_errno = errno;
 341                 error_errno("waitpid for %s failed", argv0);
 342         } else if (waiting != pid) {
 343                 error("waitpid is confused (%s)", argv0);
 344         } else if (WIFSIGNALED(status)) {
 345                 code = WTERMSIG(status);
 346                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 347                         error("%s died of signal %d", argv0, code);
 348                 /*
 349                  * This return value is chosen so that code & 0xff
 350                  * mimics the exit code that a POSIX shell would report for
 351                  * a program that died from this signal.
 352                  */
 353                 code += 128;
 354         } else if (WIFEXITED(status)) {
 355                 code = WEXITSTATUS(status);
 356                 /*
 357                  * Convert special exit code when execvp failed.
 358                  */
 359                 if (code == 127) {
 360                         code = -1;
 361                         failed_errno = ENOENT;
 362                 }
 363         } else {
 364                 error("waitpid is confused (%s)", argv0);
 365         }
 366
 367         clear_child_for_cleanup(pid);
 368
 369         errno = failed_errno;
 370         return code;
 371 }
 372
 373 int start_command(struct child_process *cmd)
 374 {
 375         int need_in, need_out, need_err;
 376         int fdin[2], fdout[2], fderr[2];
 377         int failed_errno;
 378         char *str;
 379
 380         if (!cmd->argv)
 381                 cmd->argv = cmd->args.argv;
 382         if (!cmd->env)
 383                 cmd->env = cmd->env_array.argv;
 384
 385         /*
 386          * In case of errors we must keep the promise to close FDs
 387          * that have been passed in via ->in and ->out.
 388          */
 389
 390         need_in = !cmd->no_stdin && cmd->in < 0;
 391         if (need_in) {
 392                 if (pipe(fdin) < 0) {
 393                         failed_errno = errno;
 394                         if (cmd->out > 0)
 395                                 close(cmd->out);
 396                         str = "standard input";
 397                         goto fail_pipe;
 398                 }
 399                 cmd->in = fdin[1];
 400         }
 401
 402         need_out = !cmd->no_stdout
 403                 && !cmd->stdout_to_stderr
 404                 && cmd->out < 0;
 405         if (need_out) {
 406                 if (pipe(fdout) < 0) {
 407                         failed_errno = errno;
 408                         if (need_in)
 409                                 close_pair(fdin);
 410                         else if (cmd->in)
 411                                 close(cmd->in);
 412                         str = "standard output";
 413                         goto fail_pipe;
 414                 }
 415                 cmd->out = fdout[0];
 416         }
 417
 418         need_err = !cmd->no_stderr && cmd->err < 0;
 419         if (need_err) {
 420                 if (pipe(fderr) < 0) {
 421                         failed_errno = errno;
 422                         if (need_in)
 423                                 close_pair(fdin);
 424                         else if (cmd->in)
 425                                 close(cmd->in);
 426                         if (need_out)
 427                                 close_pair(fdout);
 428                         else if (cmd->out)
 429                                 close(cmd->out);
 430                         str = "standard error";
 431 fail_pipe:
 432                         error("cannot create %s pipe for %s: %s",
 433                                 str, cmd->argv[0], strerror(failed_errno));
 434                         child_process_clear(cmd);
 435                         errno = failed_errno;
 436                         return -1;
 437                 }
 438                 cmd->err = fderr[0];
 439         }
 440
 441         trace_argv_printf(cmd->argv, "trace: run_command:");
 442         fflush(NULL);
 443
 444 #ifndef GIT_WINDOWS_NATIVE
 445 {
 446         int notify_pipe[2];
 447         char **childenv;
 448         struct argv_array argv = ARGV_ARRAY_INIT;
 449
 450         if (pipe(notify_pipe))
 451                 notify_pipe[0] = notify_pipe[1] = -1;
 452
 453         prepare_cmd(&argv, cmd);
 454         childenv = prep_childenv(cmd->env);
 455
 456         cmd->pid = fork();
 457         failed_errno = errno;
 458         if (!cmd->pid) {
 459                 /*
 460                  * Redirect the channel to write syscall error messages to
 461                  * before redirecting the process's stderr so that all die()
 462                  * in subsequent call paths use the parent's stderr.
 463                  */
 464                 if (cmd->no_stderr || need_err) {
 465                         int child_err = dup(2);
 466                         set_cloexec(child_err);
 467                         set_error_handle(fdopen(child_err, "w"));
 468                 }
 469
 470                 close(notify_pipe[0]);
 471                 set_cloexec(notify_pipe[1]);
 472                 child_notifier = notify_pipe[1];
 473                 atexit(notify_parent);
 474
 475                 if (cmd->no_stdin)
 476                         dup_devnull(0);
 477                 else if (need_in) {
 478                         dup2(fdin[0], 0);
 479                         close_pair(fdin);
 480                 } else if (cmd->in) {
 481                         dup2(cmd->in, 0);
 482                         close(cmd->in);
 483                 }
 484
 485                 if (cmd->no_stderr)
 486                         dup_devnull(2);
 487                 else if (need_err) {
 488                         dup2(fderr[1], 2);
 489                         close_pair(fderr);
 490                 } else if (cmd->err > 1) {
 491                         dup2(cmd->err, 2);
 492                         close(cmd->err);
 493                 }
 494
 495                 if (cmd->no_stdout)
 496                         dup_devnull(1);
 497                 else if (cmd->stdout_to_stderr)
 498                         dup2(2, 1);
 499                 else if (need_out) {
 500                         dup2(fdout[1], 1);
 501                         close_pair(fdout);
 502                 } else if (cmd->out > 1) {
 503                         dup2(cmd->out, 1);
 504                         close(cmd->out);
 505                 }
 506
 507                 if (cmd->dir && chdir(cmd->dir))
 508                         die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 509                             cmd->dir);
 510
 511                 /*
 512                  * Attempt to exec using the command and arguments starting at
 513                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 514                  * be used in the event exec failed with ENOEXEC at which point
 515                  * we will try to interpret the command using 'sh'.
 516                  */
 517                 execve(argv.argv[1], (char *const *) argv.argv + 1,
 518                        (char *const *) childenv);
 519                 if (errno == ENOEXEC)
 520                         execve(argv.argv[0], (char *const *) argv.argv,
 521                                (char *const *) childenv);
 522
 523                 if (errno == ENOENT) {
 524                         if (!cmd->silent_exec_failure)
 525                                 error("cannot run %s: %s", cmd->argv[0],
 526                                         strerror(ENOENT));
 527                         exit(127);
 528                 } else {
 529                         die_errno("cannot exec '%s'", cmd->argv[0]);
 530                 }
 531         }
 532         if (cmd->pid < 0)
 533                 error_errno("cannot fork() for %s", cmd->argv[0]);
 534         else if (cmd->clean_on_exit)
 535                 mark_child_for_cleanup(cmd->pid, cmd);
 536
 537         /*
 538          * Wait for child's exec. If the exec succeeds (or if fork()
 539          * failed), EOF is seen immediately by the parent. Otherwise, the
 540          * child process sends a single byte.
 541          * Note that use of this infrastructure is completely advisory,
 542          * therefore, we keep error checks minimal.
 543          */
 544         close(notify_pipe[1]);
 545         if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 546                 /*
 547                  * At this point we know that fork() succeeded, but exec()
 548                  * failed. Errors have been reported to our stderr.
 549                  */
 550                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 551                 failed_errno = errno;
 552                 cmd->pid = -1;
 553         }
 554         close(notify_pipe[0]);
 555
 556         argv_array_clear(&argv);
 557         free(childenv);
 558 }
 559 #else
 560 {
 561         int fhin = 0, fhout = 1, fherr = 2;
 562         const char **sargv = cmd->argv;
 563         struct argv_array nargv = ARGV_ARRAY_INIT;
 564
 565         if (cmd->no_stdin)
 566                 fhin = open("/dev/null", O_RDWR);
 567         else if (need_in)
 568                 fhin = dup(fdin[0]);
 569         else if (cmd->in)
 570                 fhin = dup(cmd->in);
 571
 572         if (cmd->no_stderr)
 573                 fherr = open("/dev/null", O_RDWR);
 574         else if (need_err)
 575                 fherr = dup(fderr[1]);
 576         else if (cmd->err > 2)
 577                 fherr = dup(cmd->err);
 578
 579         if (cmd->no_stdout)
 580                 fhout = open("/dev/null", O_RDWR);
 581         else if (cmd->stdout_to_stderr)
 582                 fhout = dup(fherr);
 583         else if (need_out)
 584                 fhout = dup(fdout[1]);
 585         else if (cmd->out > 1)
 586                 fhout = dup(cmd->out);
 587
 588         if (cmd->git_cmd)
 589                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 590         else if (cmd->use_shell)
 591                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 592
 593         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 594                         cmd->dir, fhin, fhout, fherr);
 595         failed_errno = errno;
 596         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 597                 error_errno("cannot spawn %s", cmd->argv[0]);
 598         if (cmd->clean_on_exit && cmd->pid >= 0)
 599                 mark_child_for_cleanup(cmd->pid, cmd);
 600
 601         argv_array_clear(&nargv);
 602         cmd->argv = sargv;
 603         if (fhin != 0)
 604                 close(fhin);
 605         if (fhout != 1)
 606                 close(fhout);
 607         if (fherr != 2)
 608                 close(fherr);
 609 }
 610 #endif
 611
 612         if (cmd->pid < 0) {
 613                 if (need_in)
 614                         close_pair(fdin);
 615                 else if (cmd->in)
 616                         close(cmd->in);
 617                 if (need_out)
 618                         close_pair(fdout);
 619                 else if (cmd->out)
 620                         close(cmd->out);
 621                 if (need_err)
 622                         close_pair(fderr);
 623                 else if (cmd->err)
 624                         close(cmd->err);
 625                 child_process_clear(cmd);
 626                 errno = failed_errno;
 627                 return -1;
 628         }
 629
 630         if (need_in)
 631                 close(fdin[0]);
 632         else if (cmd->in)
 633                 close(cmd->in);
 634
 635         if (need_out)
 636                 close(fdout[1]);
 637         else if (cmd->out)
 638                 close(cmd->out);
 639
 640         if (need_err)
 641                 close(fderr[1]);
 642         else if (cmd->err)
 643                 close(cmd->err);
 644
 645         return 0;
 646 }
 647
 648 int finish_command(struct child_process *cmd)
 649 {
 650         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 651         child_process_clear(cmd);
 652         return ret;
 653 }
 654
 655 int finish_command_in_signal(struct child_process *cmd)
 656 {
 657         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 658 }
 659
 660
 661 int run_command(struct child_process *cmd)
 662 {
 663         int code;
 664
 665         if (cmd->out < 0 || cmd->err < 0)
 666                 die("BUG: run_command with a pipe can cause deadlock");
 667
 668         code = start_command(cmd);
 669         if (code)
 670                 return code;
 671         return finish_command(cmd);
 672 }
 673
 674 int run_command_v_opt(const char **argv, int opt)
 675 {
 676         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 677 }
 678
 679 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 680 {
 681         struct child_process cmd = CHILD_PROCESS_INIT;
 682         cmd.argv = argv;
 683         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 684         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 685         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 686         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 687         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 688         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 689         cmd.dir = dir;
 690         cmd.env = env;
 691         return run_command(&cmd);
 692 }
 693
 694 #ifndef NO_PTHREADS
 695 static pthread_t main_thread;
 696 static int main_thread_set;
 697 static pthread_key_t async_key;
 698 static pthread_key_t async_die_counter;
 699
 700 static void *run_thread(void *data)
 701 {
 702         struct async *async = data;
 703         intptr_t ret;
 704
 705         if (async->isolate_sigpipe) {
 706                 sigset_t mask;
 707                 sigemptyset(&mask);
 708                 sigaddset(&mask, SIGPIPE);
 709                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 710                         ret = error("unable to block SIGPIPE in async thread");
 711                         return (void *)ret;
 712                 }
 713         }
 714
 715         pthread_setspecific(async_key, async);
 716         ret = async->proc(async->proc_in, async->proc_out, async->data);
 717         return (void *)ret;
 718 }
 719
 720 static NORETURN void die_async(const char *err, va_list params)
 721 {
 722         vreportf("fatal: ", err, params);
 723
 724         if (in_async()) {
 725                 struct async *async = pthread_getspecific(async_key);
 726                 if (async->proc_in >= 0)
 727                         close(async->proc_in);
 728                 if (async->proc_out >= 0)
 729                         close(async->proc_out);
 730                 pthread_exit((void *)128);
 731         }
 732
 733         exit(128);
 734 }
 735
 736 static int async_die_is_recursing(void)
 737 {
 738         void *ret = pthread_getspecific(async_die_counter);
 739         pthread_setspecific(async_die_counter, (void *)1);
 740         return ret != NULL;
 741 }
 742
 743 int in_async(void)
 744 {
 745         if (!main_thread_set)
 746                 return 0; /* no asyncs started yet */
 747         return !pthread_equal(main_thread, pthread_self());
 748 }
 749
 750 static void NORETURN async_exit(int code)
 751 {
 752         pthread_exit((void *)(intptr_t)code);
 753 }
 754
 755 #else
 756
 757 static struct {
 758         void (**handlers)(void);
 759         size_t nr;
 760         size_t alloc;
 761 } git_atexit_hdlrs;
 762
 763 static int git_atexit_installed;
 764
 765 static void git_atexit_dispatch(void)
 766 {
 767         size_t i;
 768
 769         for (i=git_atexit_hdlrs.nr ; i ; i--)
 770                 git_atexit_hdlrs.handlers[i-1]();
 771 }
 772
 773 static void git_atexit_clear(void)
 774 {
 775         free(git_atexit_hdlrs.handlers);
 776         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 777         git_atexit_installed = 0;
 778 }
 779
 780 #undef atexit
 781 int git_atexit(void (*handler)(void))
 782 {
 783         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 784         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 785         if (!git_atexit_installed) {
 786                 if (atexit(&git_atexit_dispatch))
 787                         return -1;
 788                 git_atexit_installed = 1;
 789         }
 790         return 0;
 791 }
 792 #define atexit git_atexit
 793
 794 static int process_is_async;
 795 int in_async(void)
 796 {
 797         return process_is_async;
 798 }
 799
 800 static void NORETURN async_exit(int code)
 801 {
 802         exit(code);
 803 }
 804
 805 #endif
 806
 807 void check_pipe(int err)
 808 {
 809         if (err == EPIPE) {
 810                 if (in_async())
 811                         async_exit(141);
 812
 813                 signal(SIGPIPE, SIG_DFL);
 814                 raise(SIGPIPE);
 815                 /* Should never happen, but just in case... */
 816                 exit(141);
 817         }
 818 }
 819
 820 int start_async(struct async *async)
 821 {
 822         int need_in, need_out;
 823         int fdin[2], fdout[2];
 824         int proc_in, proc_out;
 825
 826         need_in = async->in < 0;
 827         if (need_in) {
 828                 if (pipe(fdin) < 0) {
 829                         if (async->out > 0)
 830                                 close(async->out);
 831                         return error_errno("cannot create pipe");
 832                 }
 833                 async->in = fdin[1];
 834         }
 835
 836         need_out = async->out < 0;
 837         if (need_out) {
 838                 if (pipe(fdout) < 0) {
 839                         if (need_in)
 840                                 close_pair(fdin);
 841                         else if (async->in)
 842                                 close(async->in);
 843                         return error_errno("cannot create pipe");
 844                 }
 845                 async->out = fdout[0];
 846         }
 847
 848         if (need_in)
 849                 proc_in = fdin[0];
 850         else if (async->in)
 851                 proc_in = async->in;
 852         else
 853                 proc_in = -1;
 854
 855         if (need_out)
 856                 proc_out = fdout[1];
 857         else if (async->out)
 858                 proc_out = async->out;
 859         else
 860                 proc_out = -1;
 861
 862 #ifdef NO_PTHREADS
 863         /* Flush stdio before fork() to avoid cloning buffers */
 864         fflush(NULL);
 865
 866         async->pid = fork();
 867         if (async->pid < 0) {
 868                 error_errno("fork (async) failed");
 869                 goto error;
 870         }
 871         if (!async->pid) {
 872                 if (need_in)
 873                         close(fdin[1]);
 874                 if (need_out)
 875                         close(fdout[0]);
 876                 git_atexit_clear();
 877                 process_is_async = 1;
 878                 exit(!!async->proc(proc_in, proc_out, async->data));
 879         }
 880
 881         mark_child_for_cleanup(async->pid, NULL);
 882
 883         if (need_in)
 884                 close(fdin[0]);
 885         else if (async->in)
 886                 close(async->in);
 887
 888         if (need_out)
 889                 close(fdout[1]);
 890         else if (async->out)
 891                 close(async->out);
 892 #else
 893         if (!main_thread_set) {
 894                 /*
 895                  * We assume that the first time that start_async is called
 896                  * it is from the main thread.
 897                  */
 898                 main_thread_set = 1;
 899                 main_thread = pthread_self();
 900                 pthread_key_create(&async_key, NULL);
 901                 pthread_key_create(&async_die_counter, NULL);
 902                 set_die_routine(die_async);
 903                 set_die_is_recursing_routine(async_die_is_recursing);
 904         }
 905
 906         if (proc_in >= 0)
 907                 set_cloexec(proc_in);
 908         if (proc_out >= 0)
 909                 set_cloexec(proc_out);
 910         async->proc_in = proc_in;
 911         async->proc_out = proc_out;
 912         {
 913                 int err = pthread_create(&async->tid, NULL, run_thread, async);
 914                 if (err) {
 915                         error_errno("cannot create thread");
 916                         goto error;
 917                 }
 918         }
 919 #endif
 920         return 0;
 921
 922 error:
 923         if (need_in)
 924                 close_pair(fdin);
 925         else if (async->in)
 926                 close(async->in);
 927
 928         if (need_out)
 929                 close_pair(fdout);
 930         else if (async->out)
 931                 close(async->out);
 932         return -1;
 933 }
 934
 935 int finish_async(struct async *async)
 936 {
 937 #ifdef NO_PTHREADS
 938         return wait_or_whine(async->pid, "child process", 0);
 939 #else
 940         void *ret = (void *)(intptr_t)(-1);
 941
 942         if (pthread_join(async->tid, &ret))
 943                 error("pthread_join failed");
 944         return (int)(intptr_t)ret;
 945 #endif
 946 }
 947
 948 const char *find_hook(const char *name)
 949 {
 950         static struct strbuf path = STRBUF_INIT;
 951
 952         strbuf_reset(&path);
 953         strbuf_git_path(&path, "hooks/%s", name);
 954         if (access(path.buf, X_OK) < 0) {
 955 #ifdef STRIP_EXTENSION
 956                 strbuf_addstr(&path, STRIP_EXTENSION);
 957                 if (access(path.buf, X_OK) >= 0)
 958                         return path.buf;
 959 #endif
 960                 return NULL;
 961         }
 962         return path.buf;
 963 }
 964
 965 int run_hook_ve(const char *const *env, const char *name, va_list args)
 966 {
 967         struct child_process hook = CHILD_PROCESS_INIT;
 968         const char *p;
 969
 970         p = find_hook(name);
 971         if (!p)
 972                 return 0;
 973
 974         argv_array_push(&hook.args, p);
 975         while ((p = va_arg(args, const char *)))
 976                 argv_array_push(&hook.args, p);
 977         hook.env = env;
 978         hook.no_stdin = 1;
 979         hook.stdout_to_stderr = 1;
 980
 981         return run_command(&hook);
 982 }
 983
 984 int run_hook_le(const char *const *env, const char *name, ...)
 985 {
 986         va_list args;
 987         int ret;
 988
 989         va_start(args, name);
 990         ret = run_hook_ve(env, name, args);
 991         va_end(args);
 992
 993         return ret;
 994 }
 995
 996 struct io_pump {
 997         /* initialized by caller */
 998         int fd;
 999         int type; /* POLLOUT or POLLIN */
1000         union {
1001                 struct {
1002                         const char *buf;
1003                         size_t len;
1004                 } out;
1005                 struct {
1006                         struct strbuf *buf;
1007                         size_t hint;
1008                 } in;
1009         } u;
1010
1011         /* returned by pump_io */
1012         int error; /* 0 for success, otherwise errno */
1013
1014         /* internal use */
1015         struct pollfd *pfd;
1016 };
1017
1018 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1019 {
1020         int pollsize = 0;
1021         int i;
1022
1023         for (i = 0; i < nr; i++) {
1024                 struct io_pump *io = &slots[i];
1025                 if (io->fd < 0)
1026                         continue;
1027                 pfd[pollsize].fd = io->fd;
1028                 pfd[pollsize].events = io->type;
1029                 io->pfd = &pfd[pollsize++];
1030         }
1031
1032         if (!pollsize)
1033                 return 0;
1034
1035         if (poll(pfd, pollsize, -1) < 0) {
1036                 if (errno == EINTR)
1037                         return 1;
1038                 die_errno("poll failed");
1039         }
1040
1041         for (i = 0; i < nr; i++) {
1042                 struct io_pump *io = &slots[i];
1043
1044                 if (io->fd < 0)
1045                         continue;
1046
1047                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1048                         continue;
1049
1050                 if (io->type == POLLOUT) {
1051                         ssize_t len = xwrite(io->fd,
1052                                              io->u.out.buf, io->u.out.len);
1053                         if (len < 0) {
1054                                 io->error = errno;
1055                                 close(io->fd);
1056                                 io->fd = -1;
1057                         } else {
1058                                 io->u.out.buf += len;
1059                                 io->u.out.len -= len;
1060                                 if (!io->u.out.len) {
1061                                         close(io->fd);
1062                                         io->fd = -1;
1063                                 }
1064                         }
1065                 }
1066
1067                 if (io->type == POLLIN) {
1068                         ssize_t len = strbuf_read_once(io->u.in.buf,
1069                                                        io->fd, io->u.in.hint);
1070                         if (len < 0)
1071                                 io->error = errno;
1072                         if (len <= 0) {
1073                                 close(io->fd);
1074                                 io->fd = -1;
1075                         }
1076                 }
1077         }
1078
1079         return 1;
1080 }
1081
1082 static int pump_io(struct io_pump *slots, int nr)
1083 {
1084         struct pollfd *pfd;
1085         int i;
1086
1087         for (i = 0; i < nr; i++)
1088                 slots[i].error = 0;
1089
1090         ALLOC_ARRAY(pfd, nr);
1091         while (pump_io_round(slots, nr, pfd))
1092                 ; /* nothing */
1093         free(pfd);
1094
1095         /* There may be multiple errno values, so just pick the first. */
1096         for (i = 0; i < nr; i++) {
1097                 if (slots[i].error) {
1098                         errno = slots[i].error;
1099                         return -1;
1100                 }
1101         }
1102         return 0;
1103 }
1104
1105
1106 int pipe_command(struct child_process *cmd,
1107                  const char *in, size_t in_len,
1108                  struct strbuf *out, size_t out_hint,
1109                  struct strbuf *err, size_t err_hint)
1110 {
1111         struct io_pump io[3];
1112         int nr = 0;
1113
1114         if (in)
1115                 cmd->in = -1;
1116         if (out)
1117                 cmd->out = -1;
1118         if (err)
1119                 cmd->err = -1;
1120
1121         if (start_command(cmd) < 0)
1122                 return -1;
1123
1124         if (in) {
1125                 io[nr].fd = cmd->in;
1126                 io[nr].type = POLLOUT;
1127                 io[nr].u.out.buf = in;
1128                 io[nr].u.out.len = in_len;
1129                 nr++;
1130         }
1131         if (out) {
1132                 io[nr].fd = cmd->out;
1133                 io[nr].type = POLLIN;
1134                 io[nr].u.in.buf = out;
1135                 io[nr].u.in.hint = out_hint;
1136                 nr++;
1137         }
1138         if (err) {
1139                 io[nr].fd = cmd->err;
1140                 io[nr].type = POLLIN;
1141                 io[nr].u.in.buf = err;
1142                 io[nr].u.in.hint = err_hint;
1143                 nr++;
1144         }
1145
1146         if (pump_io(io, nr) < 0) {
1147                 finish_command(cmd); /* throw away exit code */
1148                 return -1;
1149         }
1150
1151         return finish_command(cmd);
1152 }
1153
1154 enum child_state {
1155         GIT_CP_FREE,
1156         GIT_CP_WORKING,
1157         GIT_CP_WAIT_CLEANUP,
1158 };
1159
1160 struct parallel_processes {
1161         void *data;
1162
1163         int max_processes;
1164         int nr_processes;
1165
1166         get_next_task_fn get_next_task;
1167         start_failure_fn start_failure;
1168         task_finished_fn task_finished;
1169
1170         struct {
1171                 enum child_state state;
1172                 struct child_process process;
1173                 struct strbuf err;
1174                 void *data;
1175         } *children;
1176         /*
1177          * The struct pollfd is logically part of *children,
1178          * but the system call expects it as its own array.
1179          */
1180         struct pollfd *pfd;
1181
1182         unsigned shutdown : 1;
1183
1184         int output_owner;
1185         struct strbuf buffered_output; /* of finished children */
1186 };
1187
1188 static int default_start_failure(struct strbuf *out,
1189                                  void *pp_cb,
1190                                  void *pp_task_cb)
1191 {
1192         return 0;
1193 }
1194
1195 static int default_task_finished(int result,
1196                                  struct strbuf *out,
1197                                  void *pp_cb,
1198                                  void *pp_task_cb)
1199 {
1200         return 0;
1201 }
1202
1203 static void kill_children(struct parallel_processes *pp, int signo)
1204 {
1205         int i, n = pp->max_processes;
1206
1207         for (i = 0; i < n; i++)
1208                 if (pp->children[i].state == GIT_CP_WORKING)
1209                         kill(pp->children[i].process.pid, signo);
1210 }
1211
1212 static struct parallel_processes *pp_for_signal;
1213
1214 static void handle_children_on_signal(int signo)
1215 {
1216         kill_children(pp_for_signal, signo);
1217         sigchain_pop(signo);
1218         raise(signo);
1219 }
1220
1221 static void pp_init(struct parallel_processes *pp,
1222                     int n,
1223                     get_next_task_fn get_next_task,
1224                     start_failure_fn start_failure,
1225                     task_finished_fn task_finished,
1226                     void *data)
1227 {
1228         int i;
1229
1230         if (n < 1)
1231                 n = online_cpus();
1232
1233         pp->max_processes = n;
1234
1235         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1236
1237         pp->data = data;
1238         if (!get_next_task)
1239                 die("BUG: you need to specify a get_next_task function");
1240         pp->get_next_task = get_next_task;
1241
1242         pp->start_failure = start_failure ? start_failure : default_start_failure;
1243         pp->task_finished = task_finished ? task_finished : default_task_finished;
1244
1245         pp->nr_processes = 0;
1246         pp->output_owner = 0;
1247         pp->shutdown = 0;
1248         pp->children = xcalloc(n, sizeof(*pp->children));
1249         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1250         strbuf_init(&pp->buffered_output, 0);
1251
1252         for (i = 0; i < n; i++) {
1253                 strbuf_init(&pp->children[i].err, 0);
1254                 child_process_init(&pp->children[i].process);
1255                 pp->pfd[i].events = POLLIN | POLLHUP;
1256                 pp->pfd[i].fd = -1;
1257         }
1258
1259         pp_for_signal = pp;
1260         sigchain_push_common(handle_children_on_signal);
1261 }
1262
1263 static void pp_cleanup(struct parallel_processes *pp)
1264 {
1265         int i;
1266
1267         trace_printf("run_processes_parallel: done");
1268         for (i = 0; i < pp->max_processes; i++) {
1269                 strbuf_release(&pp->children[i].err);
1270                 child_process_clear(&pp->children[i].process);
1271         }
1272
1273         free(pp->children);
1274         free(pp->pfd);
1275
1276         /*
1277          * When get_next_task added messages to the buffer in its last
1278          * iteration, the buffered output is non empty.
1279          */
1280         strbuf_write(&pp->buffered_output, stderr);
1281         strbuf_release(&pp->buffered_output);
1282
1283         sigchain_pop_common();
1284 }
1285
1286 /* returns
1287  *  0 if a new task was started.
1288  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1289  *    problem with starting a new command)
1290  * <0 no new job was started, user wishes to shutdown early. Use negative code
1291  *    to signal the children.
1292  */
1293 static int pp_start_one(struct parallel_processes *pp)
1294 {
1295         int i, code;
1296
1297         for (i = 0; i < pp->max_processes; i++)
1298                 if (pp->children[i].state == GIT_CP_FREE)
1299                         break;
1300         if (i == pp->max_processes)
1301                 die("BUG: bookkeeping is hard");
1302
1303         code = pp->get_next_task(&pp->children[i].process,
1304                                  &pp->children[i].err,
1305                                  pp->data,
1306                                  &pp->children[i].data);
1307         if (!code) {
1308                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1309                 strbuf_reset(&pp->children[i].err);
1310                 return 1;
1311         }
1312         pp->children[i].process.err = -1;
1313         pp->children[i].process.stdout_to_stderr = 1;
1314         pp->children[i].process.no_stdin = 1;
1315
1316         if (start_command(&pp->children[i].process)) {
1317                 code = pp->start_failure(&pp->children[i].err,
1318                                          pp->data,
1319                                          &pp->children[i].data);
1320                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1321                 strbuf_reset(&pp->children[i].err);
1322                 if (code)
1323                         pp->shutdown = 1;
1324                 return code;
1325         }
1326
1327         pp->nr_processes++;
1328         pp->children[i].state = GIT_CP_WORKING;
1329         pp->pfd[i].fd = pp->children[i].process.err;
1330         return 0;
1331 }
1332
1333 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1334 {
1335         int i;
1336
1337         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1338                 if (errno == EINTR)
1339                         continue;
1340                 pp_cleanup(pp);
1341                 die_errno("poll");
1342         }
1343
1344         /* Buffer output from all pipes. */
1345         for (i = 0; i < pp->max_processes; i++) {
1346                 if (pp->children[i].state == GIT_CP_WORKING &&
1347                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1348                         int n = strbuf_read_once(&pp->children[i].err,
1349                                                  pp->children[i].process.err, 0);
1350                         if (n == 0) {
1351                                 close(pp->children[i].process.err);
1352                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1353                         } else if (n < 0)
1354                                 if (errno != EAGAIN)
1355                                         die_errno("read");
1356                 }
1357         }
1358 }
1359
1360 static void pp_output(struct parallel_processes *pp)
1361 {
1362         int i = pp->output_owner;
1363         if (pp->children[i].state == GIT_CP_WORKING &&
1364             pp->children[i].err.len) {
1365                 strbuf_write(&pp->children[i].err, stderr);
1366                 strbuf_reset(&pp->children[i].err);
1367         }
1368 }
1369
1370 static int pp_collect_finished(struct parallel_processes *pp)
1371 {
1372         int i, code;
1373         int n = pp->max_processes;
1374         int result = 0;
1375
1376         while (pp->nr_processes > 0) {
1377                 for (i = 0; i < pp->max_processes; i++)
1378                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1379                                 break;
1380                 if (i == pp->max_processes)
1381                         break;
1382
1383                 code = finish_command(&pp->children[i].process);
1384
1385                 code = pp->task_finished(code,
1386                                          &pp->children[i].err, pp->data,
1387                                          &pp->children[i].data);
1388
1389                 if (code)
1390                         result = code;
1391                 if (code < 0)
1392                         break;
1393
1394                 pp->nr_processes--;
1395                 pp->children[i].state = GIT_CP_FREE;
1396                 pp->pfd[i].fd = -1;
1397                 child_process_init(&pp->children[i].process);
1398
1399                 if (i != pp->output_owner) {
1400                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1401                         strbuf_reset(&pp->children[i].err);
1402                 } else {
1403                         strbuf_write(&pp->children[i].err, stderr);
1404                         strbuf_reset(&pp->children[i].err);
1405
1406                         /* Output all other finished child processes */
1407                         strbuf_write(&pp->buffered_output, stderr);
1408                         strbuf_reset(&pp->buffered_output);
1409
1410                         /*
1411                          * Pick next process to output live.
1412                          * NEEDSWORK:
1413                          * For now we pick it randomly by doing a round
1414                          * robin. Later we may want to pick the one with
1415                          * the most output or the longest or shortest
1416                          * running process time.
1417                          */
1418                         for (i = 0; i < n; i++)
1419                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1420                                         break;
1421                         pp->output_owner = (pp->output_owner + i) % n;
1422                 }
1423         }
1424         return result;
1425 }
1426
1427 int run_processes_parallel(int n,
1428                            get_next_task_fn get_next_task,
1429                            start_failure_fn start_failure,
1430                            task_finished_fn task_finished,
1431                            void *pp_cb)
1432 {
1433         int i, code;
1434         int output_timeout = 100;
1435         int spawn_cap = 4;
1436         struct parallel_processes pp;
1437
1438         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1439         while (1) {
1440                 for (i = 0;
1441                     i < spawn_cap && !pp.shutdown &&
1442                     pp.nr_processes < pp.max_processes;
1443                     i++) {
1444                         code = pp_start_one(&pp);
1445                         if (!code)
1446                                 continue;
1447                         if (code < 0) {
1448                                 pp.shutdown = 1;
1449                                 kill_children(&pp, -code);
1450                         }
1451                         break;
1452                 }
1453                 if (!pp.nr_processes)
1454                         break;
1455                 pp_buffer_stderr(&pp, output_timeout);
1456                 pp_output(&pp);
1457                 code = pp_collect_finished(&pp);
1458                 if (code) {
1459                         pp.shutdown = 1;
1460                         if (code < 0)
1461                                 kill_children(&pp, -code);
1462                 }
1463         }
1464
1465         pp_cleanup(&pp);
1466         return 0;
1467 }