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 #include "string-list.h"
   9 #include "quote.h"
  10
  11 void child_process_init(struct child_process *child)
  12 {
  13         memset(child, 0, sizeof(*child));
  14         argv_array_init(&child->args);
  15         argv_array_init(&child->env_array);
  16 }
  17
  18 void child_process_clear(struct child_process *child)
  19 {
  20         argv_array_clear(&child->args);
  21         argv_array_clear(&child->env_array);
  22 }
  23
  24 struct child_to_clean {
  25         pid_t pid;
  26         struct child_process *process;
  27         struct child_to_clean *next;
  28 };
  29 static struct child_to_clean *children_to_clean;
  30 static int installed_child_cleanup_handler;
  31
  32 static void cleanup_children(int sig, int in_signal)
  33 {
  34         struct child_to_clean *children_to_wait_for = NULL;
  35
  36         while (children_to_clean) {
  37                 struct child_to_clean *p = children_to_clean;
  38                 children_to_clean = p->next;
  39
  40                 if (p->process && !in_signal) {
  41                         struct child_process *process = p->process;
  42                         if (process->clean_on_exit_handler) {
  43                                 trace_printf(
  44                                         "trace: run_command: running exit handler for pid %"
  45                                         PRIuMAX, (uintmax_t)p->pid
  46                                 );
  47                                 process->clean_on_exit_handler(process);
  48                         }
  49                 }
  50
  51                 kill(p->pid, sig);
  52
  53                 if (p->process && p->process->wait_after_clean) {
  54                         p->next = children_to_wait_for;
  55                         children_to_wait_for = p;
  56                 } else {
  57                         if (!in_signal)
  58                                 free(p);
  59                 }
  60         }
  61
  62         while (children_to_wait_for) {
  63                 struct child_to_clean *p = children_to_wait_for;
  64                 children_to_wait_for = p->next;
  65
  66                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  67                         ; /* spin waiting for process exit or error */
  68
  69                 if (!in_signal)
  70                         free(p);
  71         }
  72 }
  73
  74 static void cleanup_children_on_signal(int sig)
  75 {
  76         cleanup_children(sig, 1);
  77         sigchain_pop(sig);
  78         raise(sig);
  79 }
  80
  81 static void cleanup_children_on_exit(void)
  82 {
  83         cleanup_children(SIGTERM, 0);
  84 }
  85
  86 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  87 {
  88         struct child_to_clean *p = xmalloc(sizeof(*p));
  89         p->pid = pid;
  90         p->process = process;
  91         p->next = children_to_clean;
  92         children_to_clean = p;
  93
  94         if (!installed_child_cleanup_handler) {
  95                 atexit(cleanup_children_on_exit);
  96                 sigchain_push_common(cleanup_children_on_signal);
  97                 installed_child_cleanup_handler = 1;
  98         }
  99 }
 100
 101 static void clear_child_for_cleanup(pid_t pid)
 102 {
 103         struct child_to_clean **pp;
 104
 105         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 106                 struct child_to_clean *clean_me = *pp;
 107
 108                 if (clean_me->pid == pid) {
 109                         *pp = clean_me->next;
 110                         free(clean_me);
 111                         return;
 112                 }
 113         }
 114 }
 115
 116 static inline void close_pair(int fd[2])
 117 {
 118         close(fd[0]);
 119         close(fd[1]);
 120 }
 121
 122 int is_executable(const char *name)
 123 {
 124         struct stat st;
 125
 126         if (stat(name, &st) || /* stat, not lstat */
 127             !S_ISREG(st.st_mode))
 128                 return 0;
 129
 130 #if defined(GIT_WINDOWS_NATIVE)
 131         /*
 132          * On Windows there is no executable bit. The file extension
 133          * indicates whether it can be run as an executable, and Git
 134          * has special-handling to detect scripts and launch them
 135          * through the indicated script interpreter. We test for the
 136          * file extension first because virus scanners may make
 137          * it quite expensive to open many files.
 138          */
 139         if (ends_with(name, ".exe"))
 140                 return S_IXUSR;
 141
 142 {
 143         /*
 144          * Now that we know it does not have an executable extension,
 145          * peek into the file instead.
 146          */
 147         char buf[3] = { 0 };
 148         int n;
 149         int fd = open(name, O_RDONLY);
 150         st.st_mode &= ~S_IXUSR;
 151         if (fd >= 0) {
 152                 n = read(fd, buf, 2);
 153                 if (n == 2)
 154                         /* look for a she-bang */
 155                         if (!strcmp(buf, "#!"))
 156                                 st.st_mode |= S_IXUSR;
 157                 close(fd);
 158         }
 159 }
 160 #endif
 161         return st.st_mode & S_IXUSR;
 162 }
 163
 164 /*
 165  * Search $PATH for a command.  This emulates the path search that
 166  * execvp would perform, without actually executing the command so it
 167  * can be used before fork() to prepare to run a command using
 168  * execve() or after execvp() to diagnose why it failed.
 169  *
 170  * The caller should ensure that file contains no directory
 171  * separators.
 172  *
 173  * Returns the path to the command, as found in $PATH or NULL if the
 174  * command could not be found.  The caller inherits ownership of the memory
 175  * used to store the resultant path.
 176  *
 177  * This should not be used on Windows, where the $PATH search rules
 178  * are more complicated (e.g., a search for "foo" should find
 179  * "foo.exe").
 180  */
 181 static char *locate_in_PATH(const char *file)
 182 {
 183         const char *p = getenv("PATH");
 184         struct strbuf buf = STRBUF_INIT;
 185
 186         if (!p || !*p)
 187                 return NULL;
 188
 189         while (1) {
 190                 const char *end = strchrnul(p, ':');
 191
 192                 strbuf_reset(&buf);
 193
 194                 /* POSIX specifies an empty entry as the current directory. */
 195                 if (end != p) {
 196                         strbuf_add(&buf, p, end - p);
 197                         strbuf_addch(&buf, '/');
 198                 }
 199                 strbuf_addstr(&buf, file);
 200
 201                 if (is_executable(buf.buf))
 202                         return strbuf_detach(&buf, NULL);
 203
 204                 if (!*end)
 205                         break;
 206                 p = end + 1;
 207         }
 208
 209         strbuf_release(&buf);
 210         return NULL;
 211 }
 212
 213 static int exists_in_PATH(const char *file)
 214 {
 215         char *r = locate_in_PATH(file);
 216         free(r);
 217         return r != NULL;
 218 }
 219
 220 int sane_execvp(const char *file, char * const argv[])
 221 {
 222         if (!execvp(file, argv))
 223                 return 0; /* cannot happen ;-) */
 224
 225         /*
 226          * When a command can't be found because one of the directories
 227          * listed in $PATH is unsearchable, execvp reports EACCES, but
 228          * careful usability testing (read: analysis of occasional bug
 229          * reports) reveals that "No such file or directory" is more
 230          * intuitive.
 231          *
 232          * We avoid commands with "/", because execvp will not do $PATH
 233          * lookups in that case.
 234          *
 235          * The reassignment of EACCES to errno looks like a no-op below,
 236          * but we need to protect against exists_in_PATH overwriting errno.
 237          */
 238         if (errno == EACCES && !strchr(file, '/'))
 239                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 240         else if (errno == ENOTDIR && !strchr(file, '/'))
 241                 errno = ENOENT;
 242         return -1;
 243 }
 244
 245 static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 246 {
 247         if (!argv[0])
 248                 die("BUG: shell command is empty");
 249
 250         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 251 #ifndef GIT_WINDOWS_NATIVE
 252                 argv_array_push(out, SHELL_PATH);
 253 #else
 254                 argv_array_push(out, "sh");
 255 #endif
 256                 argv_array_push(out, "-c");
 257
 258                 /*
 259                  * If we have no extra arguments, we do not even need to
 260                  * bother with the "$@" magic.
 261                  */
 262                 if (!argv[1])
 263                         argv_array_push(out, argv[0]);
 264                 else
 265                         argv_array_pushf(out, "%s \"$@\"", argv[0]);
 266         }
 267
 268         argv_array_pushv(out, argv);
 269         return out->argv;
 270 }
 271
 272 #ifndef GIT_WINDOWS_NATIVE
 273 static int child_notifier = -1;
 274
 275 enum child_errcode {
 276         CHILD_ERR_CHDIR,
 277         CHILD_ERR_DUP2,
 278         CHILD_ERR_CLOSE,
 279         CHILD_ERR_SIGPROCMASK,
 280         CHILD_ERR_ENOENT,
 281         CHILD_ERR_SILENT,
 282         CHILD_ERR_ERRNO
 283 };
 284
 285 struct child_err {
 286         enum child_errcode err;
 287         int syserr; /* errno */
 288 };
 289
 290 static void child_die(enum child_errcode err)
 291 {
 292         struct child_err buf;
 293
 294         buf.err = err;
 295         buf.syserr = errno;
 296
 297         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 298         xwrite(child_notifier, &buf, sizeof(buf));
 299         _exit(1);
 300 }
 301
 302 static void child_dup2(int fd, int to)
 303 {
 304         if (dup2(fd, to) < 0)
 305                 child_die(CHILD_ERR_DUP2);
 306 }
 307
 308 static void child_close(int fd)
 309 {
 310         if (close(fd))
 311                 child_die(CHILD_ERR_CLOSE);
 312 }
 313
 314 static void child_close_pair(int fd[2])
 315 {
 316         child_close(fd[0]);
 317         child_close(fd[1]);
 318 }
 319
 320 /*
 321  * parent will make it look like the child spewed a fatal error and died
 322  * this is needed to prevent changes to t0061.
 323  */
 324 static void fake_fatal(const char *err, va_list params)
 325 {
 326         vreportf("fatal: ", err, params);
 327 }
 328
 329 static void child_error_fn(const char *err, va_list params)
 330 {
 331         const char msg[] = "error() should not be called in child\n";
 332         xwrite(2, msg, sizeof(msg) - 1);
 333 }
 334
 335 static void child_warn_fn(const char *err, va_list params)
 336 {
 337         const char msg[] = "warn() should not be called in child\n";
 338         xwrite(2, msg, sizeof(msg) - 1);
 339 }
 340
 341 static void NORETURN child_die_fn(const char *err, va_list params)
 342 {
 343         const char msg[] = "die() should not be called in child\n";
 344         xwrite(2, msg, sizeof(msg) - 1);
 345         _exit(2);
 346 }
 347
 348 /* this runs in the parent process */
 349 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 350 {
 351         static void (*old_errfn)(const char *err, va_list params);
 352
 353         old_errfn = get_error_routine();
 354         set_error_routine(fake_fatal);
 355         errno = cerr->syserr;
 356
 357         switch (cerr->err) {
 358         case CHILD_ERR_CHDIR:
 359                 error_errno("exec '%s': cd to '%s' failed",
 360                             cmd->argv[0], cmd->dir);
 361                 break;
 362         case CHILD_ERR_DUP2:
 363                 error_errno("dup2() in child failed");
 364                 break;
 365         case CHILD_ERR_CLOSE:
 366                 error_errno("close() in child failed");
 367                 break;
 368         case CHILD_ERR_SIGPROCMASK:
 369                 error_errno("sigprocmask failed restoring signals");
 370                 break;
 371         case CHILD_ERR_ENOENT:
 372                 error_errno("cannot run %s", cmd->argv[0]);
 373                 break;
 374         case CHILD_ERR_SILENT:
 375                 break;
 376         case CHILD_ERR_ERRNO:
 377                 error_errno("cannot exec '%s'", cmd->argv[0]);
 378                 break;
 379         }
 380         set_error_routine(old_errfn);
 381 }
 382
 383 static void prepare_cmd(struct argv_array *out, const struct child_process *cmd)
 384 {
 385         if (!cmd->argv[0])
 386                 die("BUG: command is empty");
 387
 388         /*
 389          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 390          * attempt to interpret the command with 'sh'.
 391          */
 392         argv_array_push(out, SHELL_PATH);
 393
 394         if (cmd->git_cmd) {
 395                 argv_array_push(out, "git");
 396                 argv_array_pushv(out, cmd->argv);
 397         } else if (cmd->use_shell) {
 398                 prepare_shell_cmd(out, cmd->argv);
 399         } else {
 400                 argv_array_pushv(out, cmd->argv);
 401         }
 402
 403         /*
 404          * If there are no '/' characters in the command then perform a path
 405          * lookup and use the resolved path as the command to exec.  If there
 406          * are no '/' characters or if the command wasn't found in the path,
 407          * have exec attempt to invoke the command directly.
 408          */
 409         if (!strchr(out->argv[1], '/')) {
 410                 char *program = locate_in_PATH(out->argv[1]);
 411                 if (program) {
 412                         free((char *)out->argv[1]);
 413                         out->argv[1] = program;
 414                 }
 415         }
 416 }
 417
 418 static char **prep_childenv(const char *const *deltaenv)
 419 {
 420         extern char **environ;
 421         char **childenv;
 422         struct string_list env = STRING_LIST_INIT_DUP;
 423         struct strbuf key = STRBUF_INIT;
 424         const char *const *p;
 425         int i;
 426
 427         /* Construct a sorted string list consisting of the current environ */
 428         for (p = (const char *const *) environ; p && *p; p++) {
 429                 const char *equals = strchr(*p, '=');
 430
 431                 if (equals) {
 432                         strbuf_reset(&key);
 433                         strbuf_add(&key, *p, equals - *p);
 434                         string_list_append(&env, key.buf)->util = (void *) *p;
 435                 } else {
 436                         string_list_append(&env, *p)->util = (void *) *p;
 437                 }
 438         }
 439         string_list_sort(&env);
 440
 441         /* Merge in 'deltaenv' with the current environ */
 442         for (p = deltaenv; p && *p; p++) {
 443                 const char *equals = strchr(*p, '=');
 444
 445                 if (equals) {
 446                         /* ('key=value'), insert or replace entry */
 447                         strbuf_reset(&key);
 448                         strbuf_add(&key, *p, equals - *p);
 449                         string_list_insert(&env, key.buf)->util = (void *) *p;
 450                 } else {
 451                         /* otherwise ('key') remove existing entry */
 452                         string_list_remove(&env, *p, 0);
 453                 }
 454         }
 455
 456         /* Create an array of 'char *' to be used as the childenv */
 457         ALLOC_ARRAY(childenv, env.nr + 1);
 458         for (i = 0; i < env.nr; i++)
 459                 childenv[i] = env.items[i].util;
 460         childenv[env.nr] = NULL;
 461
 462         string_list_clear(&env, 0);
 463         strbuf_release(&key);
 464         return childenv;
 465 }
 466
 467 struct atfork_state {
 468 #ifndef NO_PTHREADS
 469         int cs;
 470 #endif
 471         sigset_t old;
 472 };
 473
 474 #ifndef NO_PTHREADS
 475 static void bug_die(int err, const char *msg)
 476 {
 477         if (err) {
 478                 errno = err;
 479                 die_errno("BUG: %s", msg);
 480         }
 481 }
 482 #endif
 483
 484 static void atfork_prepare(struct atfork_state *as)
 485 {
 486         sigset_t all;
 487
 488         if (sigfillset(&all))
 489                 die_errno("sigfillset");
 490 #ifdef NO_PTHREADS
 491         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 492                 die_errno("sigprocmask");
 493 #else
 494         bug_die(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 495                 "blocking all signals");
 496         bug_die(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 497                 "disabling cancellation");
 498 #endif
 499 }
 500
 501 static void atfork_parent(struct atfork_state *as)
 502 {
 503 #ifdef NO_PTHREADS
 504         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 505                 die_errno("sigprocmask");
 506 #else
 507         bug_die(pthread_setcancelstate(as->cs, NULL),
 508                 "re-enabling cancellation");
 509         bug_die(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 510                 "restoring signal mask");
 511 #endif
 512 }
 513 #endif /* GIT_WINDOWS_NATIVE */
 514
 515 static inline void set_cloexec(int fd)
 516 {
 517         int flags = fcntl(fd, F_GETFD);
 518         if (flags >= 0)
 519                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 520 }
 521
 522 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 523 {
 524         int status, code = -1;
 525         pid_t waiting;
 526         int failed_errno = 0;
 527
 528         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 529                 ;       /* nothing */
 530         if (in_signal)
 531                 return 0;
 532
 533         if (waiting < 0) {
 534                 failed_errno = errno;
 535                 error_errno("waitpid for %s failed", argv0);
 536         } else if (waiting != pid) {
 537                 error("waitpid is confused (%s)", argv0);
 538         } else if (WIFSIGNALED(status)) {
 539                 code = WTERMSIG(status);
 540                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 541                         error("%s died of signal %d", argv0, code);
 542                 /*
 543                  * This return value is chosen so that code & 0xff
 544                  * mimics the exit code that a POSIX shell would report for
 545                  * a program that died from this signal.
 546                  */
 547                 code += 128;
 548         } else if (WIFEXITED(status)) {
 549                 code = WEXITSTATUS(status);
 550         } else {
 551                 error("waitpid is confused (%s)", argv0);
 552         }
 553
 554         clear_child_for_cleanup(pid);
 555
 556         errno = failed_errno;
 557         return code;
 558 }
 559
 560 static void trace_run_command(const struct child_process *cp)
 561 {
 562         struct strbuf buf = STRBUF_INIT;
 563
 564         if (!trace_want(&trace_default_key))
 565                 return;
 566
 567         strbuf_addf(&buf, "trace: run_command:");
 568         if (cp->git_cmd)
 569                 strbuf_addstr(&buf, " git");
 570         sq_quote_argv_pretty(&buf, cp->argv);
 571
 572         trace_printf("%s", buf.buf);
 573         strbuf_release(&buf);
 574 }
 575
 576 int start_command(struct child_process *cmd)
 577 {
 578         int need_in, need_out, need_err;
 579         int fdin[2], fdout[2], fderr[2];
 580         int failed_errno;
 581         char *str;
 582
 583         if (!cmd->argv)
 584                 cmd->argv = cmd->args.argv;
 585         if (!cmd->env)
 586                 cmd->env = cmd->env_array.argv;
 587
 588         /*
 589          * In case of errors we must keep the promise to close FDs
 590          * that have been passed in via ->in and ->out.
 591          */
 592
 593         need_in = !cmd->no_stdin && cmd->in < 0;
 594         if (need_in) {
 595                 if (pipe(fdin) < 0) {
 596                         failed_errno = errno;
 597                         if (cmd->out > 0)
 598                                 close(cmd->out);
 599                         str = "standard input";
 600                         goto fail_pipe;
 601                 }
 602                 cmd->in = fdin[1];
 603         }
 604
 605         need_out = !cmd->no_stdout
 606                 && !cmd->stdout_to_stderr
 607                 && cmd->out < 0;
 608         if (need_out) {
 609                 if (pipe(fdout) < 0) {
 610                         failed_errno = errno;
 611                         if (need_in)
 612                                 close_pair(fdin);
 613                         else if (cmd->in)
 614                                 close(cmd->in);
 615                         str = "standard output";
 616                         goto fail_pipe;
 617                 }
 618                 cmd->out = fdout[0];
 619         }
 620
 621         need_err = !cmd->no_stderr && cmd->err < 0;
 622         if (need_err) {
 623                 if (pipe(fderr) < 0) {
 624                         failed_errno = errno;
 625                         if (need_in)
 626                                 close_pair(fdin);
 627                         else if (cmd->in)
 628                                 close(cmd->in);
 629                         if (need_out)
 630                                 close_pair(fdout);
 631                         else if (cmd->out)
 632                                 close(cmd->out);
 633                         str = "standard error";
 634 fail_pipe:
 635                         error("cannot create %s pipe for %s: %s",
 636                                 str, cmd->argv[0], strerror(failed_errno));
 637                         child_process_clear(cmd);
 638                         errno = failed_errno;
 639                         return -1;
 640                 }
 641                 cmd->err = fderr[0];
 642         }
 643
 644         trace_run_command(cmd);
 645
 646         fflush(NULL);
 647
 648 #ifndef GIT_WINDOWS_NATIVE
 649 {
 650         int notify_pipe[2];
 651         int null_fd = -1;
 652         char **childenv;
 653         struct argv_array argv = ARGV_ARRAY_INIT;
 654         struct child_err cerr;
 655         struct atfork_state as;
 656
 657         if (pipe(notify_pipe))
 658                 notify_pipe[0] = notify_pipe[1] = -1;
 659
 660         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 661                 null_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
 662                 if (null_fd < 0)
 663                         die_errno(_("open /dev/null failed"));
 664                 set_cloexec(null_fd);
 665         }
 666
 667         prepare_cmd(&argv, cmd);
 668         childenv = prep_childenv(cmd->env);
 669         atfork_prepare(&as);
 670
 671         /*
 672          * NOTE: In order to prevent deadlocking when using threads special
 673          * care should be taken with the function calls made in between the
 674          * fork() and exec() calls.  No calls should be made to functions which
 675          * require acquiring a lock (e.g. malloc) as the lock could have been
 676          * held by another thread at the time of forking, causing the lock to
 677          * never be released in the child process.  This means only
 678          * Async-Signal-Safe functions are permitted in the child.
 679          */
 680         cmd->pid = fork();
 681         failed_errno = errno;
 682         if (!cmd->pid) {
 683                 int sig;
 684                 /*
 685                  * Ensure the default die/error/warn routines do not get
 686                  * called, they can take stdio locks and malloc.
 687                  */
 688                 set_die_routine(child_die_fn);
 689                 set_error_routine(child_error_fn);
 690                 set_warn_routine(child_warn_fn);
 691
 692                 close(notify_pipe[0]);
 693                 set_cloexec(notify_pipe[1]);
 694                 child_notifier = notify_pipe[1];
 695
 696                 if (cmd->no_stdin)
 697                         child_dup2(null_fd, 0);
 698                 else if (need_in) {
 699                         child_dup2(fdin[0], 0);
 700                         child_close_pair(fdin);
 701                 } else if (cmd->in) {
 702                         child_dup2(cmd->in, 0);
 703                         child_close(cmd->in);
 704                 }
 705
 706                 if (cmd->no_stderr)
 707                         child_dup2(null_fd, 2);
 708                 else if (need_err) {
 709                         child_dup2(fderr[1], 2);
 710                         child_close_pair(fderr);
 711                 } else if (cmd->err > 1) {
 712                         child_dup2(cmd->err, 2);
 713                         child_close(cmd->err);
 714                 }
 715
 716                 if (cmd->no_stdout)
 717                         child_dup2(null_fd, 1);
 718                 else if (cmd->stdout_to_stderr)
 719                         child_dup2(2, 1);
 720                 else if (need_out) {
 721                         child_dup2(fdout[1], 1);
 722                         child_close_pair(fdout);
 723                 } else if (cmd->out > 1) {
 724                         child_dup2(cmd->out, 1);
 725                         child_close(cmd->out);
 726                 }
 727
 728                 if (cmd->dir && chdir(cmd->dir))
 729                         child_die(CHILD_ERR_CHDIR);
 730
 731                 /*
 732                  * restore default signal handlers here, in case
 733                  * we catch a signal right before execve below
 734                  */
 735                 for (sig = 1; sig < NSIG; sig++) {
 736                         /* ignored signals get reset to SIG_DFL on execve */
 737                         if (signal(sig, SIG_DFL) == SIG_IGN)
 738                                 signal(sig, SIG_IGN);
 739                 }
 740
 741                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 742                         child_die(CHILD_ERR_SIGPROCMASK);
 743
 744                 /*
 745                  * Attempt to exec using the command and arguments starting at
 746                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 747                  * be used in the event exec failed with ENOEXEC at which point
 748                  * we will try to interpret the command using 'sh'.
 749                  */
 750                 execve(argv.argv[1], (char *const *) argv.argv + 1,
 751                        (char *const *) childenv);
 752                 if (errno == ENOEXEC)
 753                         execve(argv.argv[0], (char *const *) argv.argv,
 754                                (char *const *) childenv);
 755
 756                 if (errno == ENOENT) {
 757                         if (cmd->silent_exec_failure)
 758                                 child_die(CHILD_ERR_SILENT);
 759                         child_die(CHILD_ERR_ENOENT);
 760                 } else {
 761                         child_die(CHILD_ERR_ERRNO);
 762                 }
 763         }
 764         atfork_parent(&as);
 765         if (cmd->pid < 0)
 766                 error_errno("cannot fork() for %s", cmd->argv[0]);
 767         else if (cmd->clean_on_exit)
 768                 mark_child_for_cleanup(cmd->pid, cmd);
 769
 770         /*
 771          * Wait for child's exec. If the exec succeeds (or if fork()
 772          * failed), EOF is seen immediately by the parent. Otherwise, the
 773          * child process sends a child_err struct.
 774          * Note that use of this infrastructure is completely advisory,
 775          * therefore, we keep error checks minimal.
 776          */
 777         close(notify_pipe[1]);
 778         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 779                 /*
 780                  * At this point we know that fork() succeeded, but exec()
 781                  * failed. Errors have been reported to our stderr.
 782                  */
 783                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 784                 child_err_spew(cmd, &cerr);
 785                 failed_errno = errno;
 786                 cmd->pid = -1;
 787         }
 788         close(notify_pipe[0]);
 789
 790         if (null_fd >= 0)
 791                 close(null_fd);
 792         argv_array_clear(&argv);
 793         free(childenv);
 794 }
 795 #else
 796 {
 797         int fhin = 0, fhout = 1, fherr = 2;
 798         const char **sargv = cmd->argv;
 799         struct argv_array nargv = ARGV_ARRAY_INIT;
 800
 801         if (cmd->no_stdin)
 802                 fhin = open("/dev/null", O_RDWR);
 803         else if (need_in)
 804                 fhin = dup(fdin[0]);
 805         else if (cmd->in)
 806                 fhin = dup(cmd->in);
 807
 808         if (cmd->no_stderr)
 809                 fherr = open("/dev/null", O_RDWR);
 810         else if (need_err)
 811                 fherr = dup(fderr[1]);
 812         else if (cmd->err > 2)
 813                 fherr = dup(cmd->err);
 814
 815         if (cmd->no_stdout)
 816                 fhout = open("/dev/null", O_RDWR);
 817         else if (cmd->stdout_to_stderr)
 818                 fhout = dup(fherr);
 819         else if (need_out)
 820                 fhout = dup(fdout[1]);
 821         else if (cmd->out > 1)
 822                 fhout = dup(cmd->out);
 823
 824         if (cmd->git_cmd)
 825                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 826         else if (cmd->use_shell)
 827                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 828
 829         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 830                         cmd->dir, fhin, fhout, fherr);
 831         failed_errno = errno;
 832         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 833                 error_errno("cannot spawn %s", cmd->argv[0]);
 834         if (cmd->clean_on_exit && cmd->pid >= 0)
 835                 mark_child_for_cleanup(cmd->pid, cmd);
 836
 837         argv_array_clear(&nargv);
 838         cmd->argv = sargv;
 839         if (fhin != 0)
 840                 close(fhin);
 841         if (fhout != 1)
 842                 close(fhout);
 843         if (fherr != 2)
 844                 close(fherr);
 845 }
 846 #endif
 847
 848         if (cmd->pid < 0) {
 849                 if (need_in)
 850                         close_pair(fdin);
 851                 else if (cmd->in)
 852                         close(cmd->in);
 853                 if (need_out)
 854                         close_pair(fdout);
 855                 else if (cmd->out)
 856                         close(cmd->out);
 857                 if (need_err)
 858                         close_pair(fderr);
 859                 else if (cmd->err)
 860                         close(cmd->err);
 861                 child_process_clear(cmd);
 862                 errno = failed_errno;
 863                 return -1;
 864         }
 865
 866         if (need_in)
 867                 close(fdin[0]);
 868         else if (cmd->in)
 869                 close(cmd->in);
 870
 871         if (need_out)
 872                 close(fdout[1]);
 873         else if (cmd->out)
 874                 close(cmd->out);
 875
 876         if (need_err)
 877                 close(fderr[1]);
 878         else if (cmd->err)
 879                 close(cmd->err);
 880
 881         return 0;
 882 }
 883
 884 int finish_command(struct child_process *cmd)
 885 {
 886         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 887         child_process_clear(cmd);
 888         return ret;
 889 }
 890
 891 int finish_command_in_signal(struct child_process *cmd)
 892 {
 893         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 894 }
 895
 896
 897 int run_command(struct child_process *cmd)
 898 {
 899         int code;
 900
 901         if (cmd->out < 0 || cmd->err < 0)
 902                 die("BUG: run_command with a pipe can cause deadlock");
 903
 904         code = start_command(cmd);
 905         if (code)
 906                 return code;
 907         return finish_command(cmd);
 908 }
 909
 910 int run_command_v_opt(const char **argv, int opt)
 911 {
 912         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 913 }
 914
 915 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 916 {
 917         struct child_process cmd = CHILD_PROCESS_INIT;
 918         cmd.argv = argv;
 919         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 920         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 921         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 922         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 923         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 924         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 925         cmd.dir = dir;
 926         cmd.env = env;
 927         return run_command(&cmd);
 928 }
 929
 930 #ifndef NO_PTHREADS
 931 static pthread_t main_thread;
 932 static int main_thread_set;
 933 static pthread_key_t async_key;
 934 static pthread_key_t async_die_counter;
 935
 936 static void *run_thread(void *data)
 937 {
 938         struct async *async = data;
 939         intptr_t ret;
 940
 941         if (async->isolate_sigpipe) {
 942                 sigset_t mask;
 943                 sigemptyset(&mask);
 944                 sigaddset(&mask, SIGPIPE);
 945                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 946                         ret = error("unable to block SIGPIPE in async thread");
 947                         return (void *)ret;
 948                 }
 949         }
 950
 951         pthread_setspecific(async_key, async);
 952         ret = async->proc(async->proc_in, async->proc_out, async->data);
 953         return (void *)ret;
 954 }
 955
 956 static NORETURN void die_async(const char *err, va_list params)
 957 {
 958         vreportf("fatal: ", err, params);
 959
 960         if (in_async()) {
 961                 struct async *async = pthread_getspecific(async_key);
 962                 if (async->proc_in >= 0)
 963                         close(async->proc_in);
 964                 if (async->proc_out >= 0)
 965                         close(async->proc_out);
 966                 pthread_exit((void *)128);
 967         }
 968
 969         exit(128);
 970 }
 971
 972 static int async_die_is_recursing(void)
 973 {
 974         void *ret = pthread_getspecific(async_die_counter);
 975         pthread_setspecific(async_die_counter, (void *)1);
 976         return ret != NULL;
 977 }
 978
 979 int in_async(void)
 980 {
 981         if (!main_thread_set)
 982                 return 0; /* no asyncs started yet */
 983         return !pthread_equal(main_thread, pthread_self());
 984 }
 985
 986 static void NORETURN async_exit(int code)
 987 {
 988         pthread_exit((void *)(intptr_t)code);
 989 }
 990
 991 #else
 992
 993 static struct {
 994         void (**handlers)(void);
 995         size_t nr;
 996         size_t alloc;
 997 } git_atexit_hdlrs;
 998
 999 static int git_atexit_installed;
1000
1001 static void git_atexit_dispatch(void)
1002 {
1003         size_t i;
1004
1005         for (i=git_atexit_hdlrs.nr ; i ; i--)
1006                 git_atexit_hdlrs.handlers[i-1]();
1007 }
1008
1009 static void git_atexit_clear(void)
1010 {
1011         free(git_atexit_hdlrs.handlers);
1012         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1013         git_atexit_installed = 0;
1014 }
1015
1016 #undef atexit
1017 int git_atexit(void (*handler)(void))
1018 {
1019         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1020         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1021         if (!git_atexit_installed) {
1022                 if (atexit(&git_atexit_dispatch))
1023                         return -1;
1024                 git_atexit_installed = 1;
1025         }
1026         return 0;
1027 }
1028 #define atexit git_atexit
1029
1030 static int process_is_async;
1031 int in_async(void)
1032 {
1033         return process_is_async;
1034 }
1035
1036 static void NORETURN async_exit(int code)
1037 {
1038         exit(code);
1039 }
1040
1041 #endif
1042
1043 void check_pipe(int err)
1044 {
1045         if (err == EPIPE) {
1046                 if (in_async())
1047                         async_exit(141);
1048
1049                 signal(SIGPIPE, SIG_DFL);
1050                 raise(SIGPIPE);
1051                 /* Should never happen, but just in case... */
1052                 exit(141);
1053         }
1054 }
1055
1056 int start_async(struct async *async)
1057 {
1058         int need_in, need_out;
1059         int fdin[2], fdout[2];
1060         int proc_in, proc_out;
1061
1062         need_in = async->in < 0;
1063         if (need_in) {
1064                 if (pipe(fdin) < 0) {
1065                         if (async->out > 0)
1066                                 close(async->out);
1067                         return error_errno("cannot create pipe");
1068                 }
1069                 async->in = fdin[1];
1070         }
1071
1072         need_out = async->out < 0;
1073         if (need_out) {
1074                 if (pipe(fdout) < 0) {
1075                         if (need_in)
1076                                 close_pair(fdin);
1077                         else if (async->in)
1078                                 close(async->in);
1079                         return error_errno("cannot create pipe");
1080                 }
1081                 async->out = fdout[0];
1082         }
1083
1084         if (need_in)
1085                 proc_in = fdin[0];
1086         else if (async->in)
1087                 proc_in = async->in;
1088         else
1089                 proc_in = -1;
1090
1091         if (need_out)
1092                 proc_out = fdout[1];
1093         else if (async->out)
1094                 proc_out = async->out;
1095         else
1096                 proc_out = -1;
1097
1098 #ifdef NO_PTHREADS
1099         /* Flush stdio before fork() to avoid cloning buffers */
1100         fflush(NULL);
1101
1102         async->pid = fork();
1103         if (async->pid < 0) {
1104                 error_errno("fork (async) failed");
1105                 goto error;
1106         }
1107         if (!async->pid) {
1108                 if (need_in)
1109                         close(fdin[1]);
1110                 if (need_out)
1111                         close(fdout[0]);
1112                 git_atexit_clear();
1113                 process_is_async = 1;
1114                 exit(!!async->proc(proc_in, proc_out, async->data));
1115         }
1116
1117         mark_child_for_cleanup(async->pid, NULL);
1118
1119         if (need_in)
1120                 close(fdin[0]);
1121         else if (async->in)
1122                 close(async->in);
1123
1124         if (need_out)
1125                 close(fdout[1]);
1126         else if (async->out)
1127                 close(async->out);
1128 #else
1129         if (!main_thread_set) {
1130                 /*
1131                  * We assume that the first time that start_async is called
1132                  * it is from the main thread.
1133                  */
1134                 main_thread_set = 1;
1135                 main_thread = pthread_self();
1136                 pthread_key_create(&async_key, NULL);
1137                 pthread_key_create(&async_die_counter, NULL);
1138                 set_die_routine(die_async);
1139                 set_die_is_recursing_routine(async_die_is_recursing);
1140         }
1141
1142         if (proc_in >= 0)
1143                 set_cloexec(proc_in);
1144         if (proc_out >= 0)
1145                 set_cloexec(proc_out);
1146         async->proc_in = proc_in;
1147         async->proc_out = proc_out;
1148         {
1149                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1150                 if (err) {
1151                         error_errno("cannot create thread");
1152                         goto error;
1153                 }
1154         }
1155 #endif
1156         return 0;
1157
1158 error:
1159         if (need_in)
1160                 close_pair(fdin);
1161         else if (async->in)
1162                 close(async->in);
1163
1164         if (need_out)
1165                 close_pair(fdout);
1166         else if (async->out)
1167                 close(async->out);
1168         return -1;
1169 }
1170
1171 int finish_async(struct async *async)
1172 {
1173 #ifdef NO_PTHREADS
1174         return wait_or_whine(async->pid, "child process", 0);
1175 #else
1176         void *ret = (void *)(intptr_t)(-1);
1177
1178         if (pthread_join(async->tid, &ret))
1179                 error("pthread_join failed");
1180         return (int)(intptr_t)ret;
1181 #endif
1182 }
1183
1184 const char *find_hook(const char *name)
1185 {
1186         static struct strbuf path = STRBUF_INIT;
1187
1188         strbuf_reset(&path);
1189         strbuf_git_path(&path, "hooks/%s", name);
1190         if (access(path.buf, X_OK) < 0) {
1191                 int err = errno;
1192
1193 #ifdef STRIP_EXTENSION
1194                 strbuf_addstr(&path, STRIP_EXTENSION);
1195                 if (access(path.buf, X_OK) >= 0)
1196                         return path.buf;
1197                 if (errno == EACCES)
1198                         err = errno;
1199 #endif
1200
1201                 if (err == EACCES && advice_ignored_hook) {
1202                         static struct string_list advise_given = STRING_LIST_INIT_DUP;
1203
1204                         if (!string_list_lookup(&advise_given, name)) {
1205                                 string_list_insert(&advise_given, name);
1206                                 advise(_("The '%s' hook was ignored because "
1207                                          "it's not set as executable.\n"
1208                                          "You can disable this warning with "
1209                                          "`git config advice.ignoredHook false`."),
1210                                        path.buf);
1211                         }
1212                 }
1213                 return NULL;
1214         }
1215         return path.buf;
1216 }
1217
1218 int run_hook_ve(const char *const *env, const char *name, va_list args)
1219 {
1220         struct child_process hook = CHILD_PROCESS_INIT;
1221         const char *p;
1222
1223         p = find_hook(name);
1224         if (!p)
1225                 return 0;
1226
1227         argv_array_push(&hook.args, p);
1228         while ((p = va_arg(args, const char *)))
1229                 argv_array_push(&hook.args, p);
1230         hook.env = env;
1231         hook.no_stdin = 1;
1232         hook.stdout_to_stderr = 1;
1233
1234         return run_command(&hook);
1235 }
1236
1237 int run_hook_le(const char *const *env, const char *name, ...)
1238 {
1239         va_list args;
1240         int ret;
1241
1242         va_start(args, name);
1243         ret = run_hook_ve(env, name, args);
1244         va_end(args);
1245
1246         return ret;
1247 }
1248
1249 struct io_pump {
1250         /* initialized by caller */
1251         int fd;
1252         int type; /* POLLOUT or POLLIN */
1253         union {
1254                 struct {
1255                         const char *buf;
1256                         size_t len;
1257                 } out;
1258                 struct {
1259                         struct strbuf *buf;
1260                         size_t hint;
1261                 } in;
1262         } u;
1263
1264         /* returned by pump_io */
1265         int error; /* 0 for success, otherwise errno */
1266
1267         /* internal use */
1268         struct pollfd *pfd;
1269 };
1270
1271 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1272 {
1273         int pollsize = 0;
1274         int i;
1275
1276         for (i = 0; i < nr; i++) {
1277                 struct io_pump *io = &slots[i];
1278                 if (io->fd < 0)
1279                         continue;
1280                 pfd[pollsize].fd = io->fd;
1281                 pfd[pollsize].events = io->type;
1282                 io->pfd = &pfd[pollsize++];
1283         }
1284
1285         if (!pollsize)
1286                 return 0;
1287
1288         if (poll(pfd, pollsize, -1) < 0) {
1289                 if (errno == EINTR)
1290                         return 1;
1291                 die_errno("poll failed");
1292         }
1293
1294         for (i = 0; i < nr; i++) {
1295                 struct io_pump *io = &slots[i];
1296
1297                 if (io->fd < 0)
1298                         continue;
1299
1300                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1301                         continue;
1302
1303                 if (io->type == POLLOUT) {
1304                         ssize_t len = xwrite(io->fd,
1305                                              io->u.out.buf, io->u.out.len);
1306                         if (len < 0) {
1307                                 io->error = errno;
1308                                 close(io->fd);
1309                                 io->fd = -1;
1310                         } else {
1311                                 io->u.out.buf += len;
1312                                 io->u.out.len -= len;
1313                                 if (!io->u.out.len) {
1314                                         close(io->fd);
1315                                         io->fd = -1;
1316                                 }
1317                         }
1318                 }
1319
1320                 if (io->type == POLLIN) {
1321                         ssize_t len = strbuf_read_once(io->u.in.buf,
1322                                                        io->fd, io->u.in.hint);
1323                         if (len < 0)
1324                                 io->error = errno;
1325                         if (len <= 0) {
1326                                 close(io->fd);
1327                                 io->fd = -1;
1328                         }
1329                 }
1330         }
1331
1332         return 1;
1333 }
1334
1335 static int pump_io(struct io_pump *slots, int nr)
1336 {
1337         struct pollfd *pfd;
1338         int i;
1339
1340         for (i = 0; i < nr; i++)
1341                 slots[i].error = 0;
1342
1343         ALLOC_ARRAY(pfd, nr);
1344         while (pump_io_round(slots, nr, pfd))
1345                 ; /* nothing */
1346         free(pfd);
1347
1348         /* There may be multiple errno values, so just pick the first. */
1349         for (i = 0; i < nr; i++) {
1350                 if (slots[i].error) {
1351                         errno = slots[i].error;
1352                         return -1;
1353                 }
1354         }
1355         return 0;
1356 }
1357
1358
1359 int pipe_command(struct child_process *cmd,
1360                  const char *in, size_t in_len,
1361                  struct strbuf *out, size_t out_hint,
1362                  struct strbuf *err, size_t err_hint)
1363 {
1364         struct io_pump io[3];
1365         int nr = 0;
1366
1367         if (in)
1368                 cmd->in = -1;
1369         if (out)
1370                 cmd->out = -1;
1371         if (err)
1372                 cmd->err = -1;
1373
1374         if (start_command(cmd) < 0)
1375                 return -1;
1376
1377         if (in) {
1378                 io[nr].fd = cmd->in;
1379                 io[nr].type = POLLOUT;
1380                 io[nr].u.out.buf = in;
1381                 io[nr].u.out.len = in_len;
1382                 nr++;
1383         }
1384         if (out) {
1385                 io[nr].fd = cmd->out;
1386                 io[nr].type = POLLIN;
1387                 io[nr].u.in.buf = out;
1388                 io[nr].u.in.hint = out_hint;
1389                 nr++;
1390         }
1391         if (err) {
1392                 io[nr].fd = cmd->err;
1393                 io[nr].type = POLLIN;
1394                 io[nr].u.in.buf = err;
1395                 io[nr].u.in.hint = err_hint;
1396                 nr++;
1397         }
1398
1399         if (pump_io(io, nr) < 0) {
1400                 finish_command(cmd); /* throw away exit code */
1401                 return -1;
1402         }
1403
1404         return finish_command(cmd);
1405 }
1406
1407 enum child_state {
1408         GIT_CP_FREE,
1409         GIT_CP_WORKING,
1410         GIT_CP_WAIT_CLEANUP,
1411 };
1412
1413 struct parallel_processes {
1414         void *data;
1415
1416         int max_processes;
1417         int nr_processes;
1418
1419         get_next_task_fn get_next_task;
1420         start_failure_fn start_failure;
1421         task_finished_fn task_finished;
1422
1423         struct {
1424                 enum child_state state;
1425                 struct child_process process;
1426                 struct strbuf err;
1427                 void *data;
1428         } *children;
1429         /*
1430          * The struct pollfd is logically part of *children,
1431          * but the system call expects it as its own array.
1432          */
1433         struct pollfd *pfd;
1434
1435         unsigned shutdown : 1;
1436
1437         int output_owner;
1438         struct strbuf buffered_output; /* of finished children */
1439 };
1440
1441 static int default_start_failure(struct strbuf *out,
1442                                  void *pp_cb,
1443                                  void *pp_task_cb)
1444 {
1445         return 0;
1446 }
1447
1448 static int default_task_finished(int result,
1449                                  struct strbuf *out,
1450                                  void *pp_cb,
1451                                  void *pp_task_cb)
1452 {
1453         return 0;
1454 }
1455
1456 static void kill_children(struct parallel_processes *pp, int signo)
1457 {
1458         int i, n = pp->max_processes;
1459
1460         for (i = 0; i < n; i++)
1461                 if (pp->children[i].state == GIT_CP_WORKING)
1462                         kill(pp->children[i].process.pid, signo);
1463 }
1464
1465 static struct parallel_processes *pp_for_signal;
1466
1467 static void handle_children_on_signal(int signo)
1468 {
1469         kill_children(pp_for_signal, signo);
1470         sigchain_pop(signo);
1471         raise(signo);
1472 }
1473
1474 static void pp_init(struct parallel_processes *pp,
1475                     int n,
1476                     get_next_task_fn get_next_task,
1477                     start_failure_fn start_failure,
1478                     task_finished_fn task_finished,
1479                     void *data)
1480 {
1481         int i;
1482
1483         if (n < 1)
1484                 n = online_cpus();
1485
1486         pp->max_processes = n;
1487
1488         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1489
1490         pp->data = data;
1491         if (!get_next_task)
1492                 die("BUG: you need to specify a get_next_task function");
1493         pp->get_next_task = get_next_task;
1494
1495         pp->start_failure = start_failure ? start_failure : default_start_failure;
1496         pp->task_finished = task_finished ? task_finished : default_task_finished;
1497
1498         pp->nr_processes = 0;
1499         pp->output_owner = 0;
1500         pp->shutdown = 0;
1501         pp->children = xcalloc(n, sizeof(*pp->children));
1502         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1503         strbuf_init(&pp->buffered_output, 0);
1504
1505         for (i = 0; i < n; i++) {
1506                 strbuf_init(&pp->children[i].err, 0);
1507                 child_process_init(&pp->children[i].process);
1508                 pp->pfd[i].events = POLLIN | POLLHUP;
1509                 pp->pfd[i].fd = -1;
1510         }
1511
1512         pp_for_signal = pp;
1513         sigchain_push_common(handle_children_on_signal);
1514 }
1515
1516 static void pp_cleanup(struct parallel_processes *pp)
1517 {
1518         int i;
1519
1520         trace_printf("run_processes_parallel: done");
1521         for (i = 0; i < pp->max_processes; i++) {
1522                 strbuf_release(&pp->children[i].err);
1523                 child_process_clear(&pp->children[i].process);
1524         }
1525
1526         free(pp->children);
1527         free(pp->pfd);
1528
1529         /*
1530          * When get_next_task added messages to the buffer in its last
1531          * iteration, the buffered output is non empty.
1532          */
1533         strbuf_write(&pp->buffered_output, stderr);
1534         strbuf_release(&pp->buffered_output);
1535
1536         sigchain_pop_common();
1537 }
1538
1539 /* returns
1540  *  0 if a new task was started.
1541  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1542  *    problem with starting a new command)
1543  * <0 no new job was started, user wishes to shutdown early. Use negative code
1544  *    to signal the children.
1545  */
1546 static int pp_start_one(struct parallel_processes *pp)
1547 {
1548         int i, code;
1549
1550         for (i = 0; i < pp->max_processes; i++)
1551                 if (pp->children[i].state == GIT_CP_FREE)
1552                         break;
1553         if (i == pp->max_processes)
1554                 die("BUG: bookkeeping is hard");
1555
1556         code = pp->get_next_task(&pp->children[i].process,
1557                                  &pp->children[i].err,
1558                                  pp->data,
1559                                  &pp->children[i].data);
1560         if (!code) {
1561                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1562                 strbuf_reset(&pp->children[i].err);
1563                 return 1;
1564         }
1565         pp->children[i].process.err = -1;
1566         pp->children[i].process.stdout_to_stderr = 1;
1567         pp->children[i].process.no_stdin = 1;
1568
1569         if (start_command(&pp->children[i].process)) {
1570                 code = pp->start_failure(&pp->children[i].err,
1571                                          pp->data,
1572                                          pp->children[i].data);
1573                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1574                 strbuf_reset(&pp->children[i].err);
1575                 if (code)
1576                         pp->shutdown = 1;
1577                 return code;
1578         }
1579
1580         pp->nr_processes++;
1581         pp->children[i].state = GIT_CP_WORKING;
1582         pp->pfd[i].fd = pp->children[i].process.err;
1583         return 0;
1584 }
1585
1586 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1587 {
1588         int i;
1589
1590         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1591                 if (errno == EINTR)
1592                         continue;
1593                 pp_cleanup(pp);
1594                 die_errno("poll");
1595         }
1596
1597         /* Buffer output from all pipes. */
1598         for (i = 0; i < pp->max_processes; i++) {
1599                 if (pp->children[i].state == GIT_CP_WORKING &&
1600                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1601                         int n = strbuf_read_once(&pp->children[i].err,
1602                                                  pp->children[i].process.err, 0);
1603                         if (n == 0) {
1604                                 close(pp->children[i].process.err);
1605                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1606                         } else if (n < 0)
1607                                 if (errno != EAGAIN)
1608                                         die_errno("read");
1609                 }
1610         }
1611 }
1612
1613 static void pp_output(struct parallel_processes *pp)
1614 {
1615         int i = pp->output_owner;
1616         if (pp->children[i].state == GIT_CP_WORKING &&
1617             pp->children[i].err.len) {
1618                 strbuf_write(&pp->children[i].err, stderr);
1619                 strbuf_reset(&pp->children[i].err);
1620         }
1621 }
1622
1623 static int pp_collect_finished(struct parallel_processes *pp)
1624 {
1625         int i, code;
1626         int n = pp->max_processes;
1627         int result = 0;
1628
1629         while (pp->nr_processes > 0) {
1630                 for (i = 0; i < pp->max_processes; i++)
1631                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1632                                 break;
1633                 if (i == pp->max_processes)
1634                         break;
1635
1636                 code = finish_command(&pp->children[i].process);
1637
1638                 code = pp->task_finished(code,
1639                                          &pp->children[i].err, pp->data,
1640                                          pp->children[i].data);
1641
1642                 if (code)
1643                         result = code;
1644                 if (code < 0)
1645                         break;
1646
1647                 pp->nr_processes--;
1648                 pp->children[i].state = GIT_CP_FREE;
1649                 pp->pfd[i].fd = -1;
1650                 child_process_init(&pp->children[i].process);
1651
1652                 if (i != pp->output_owner) {
1653                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1654                         strbuf_reset(&pp->children[i].err);
1655                 } else {
1656                         strbuf_write(&pp->children[i].err, stderr);
1657                         strbuf_reset(&pp->children[i].err);
1658
1659                         /* Output all other finished child processes */
1660                         strbuf_write(&pp->buffered_output, stderr);
1661                         strbuf_reset(&pp->buffered_output);
1662
1663                         /*
1664                          * Pick next process to output live.
1665                          * NEEDSWORK:
1666                          * For now we pick it randomly by doing a round
1667                          * robin. Later we may want to pick the one with
1668                          * the most output or the longest or shortest
1669                          * running process time.
1670                          */
1671                         for (i = 0; i < n; i++)
1672                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1673                                         break;
1674                         pp->output_owner = (pp->output_owner + i) % n;
1675                 }
1676         }
1677         return result;
1678 }
1679
1680 int run_processes_parallel(int n,
1681                            get_next_task_fn get_next_task,
1682                            start_failure_fn start_failure,
1683                            task_finished_fn task_finished,
1684                            void *pp_cb)
1685 {
1686         int i, code;
1687         int output_timeout = 100;
1688         int spawn_cap = 4;
1689         struct parallel_processes pp;
1690
1691         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1692         while (1) {
1693                 for (i = 0;
1694                     i < spawn_cap && !pp.shutdown &&
1695                     pp.nr_processes < pp.max_processes;
1696                     i++) {
1697                         code = pp_start_one(&pp);
1698                         if (!code)
1699                                 continue;
1700                         if (code < 0) {
1701                                 pp.shutdown = 1;
1702                                 kill_children(&pp, -code);
1703                         }
1704                         break;
1705                 }
1706                 if (!pp.nr_processes)
1707                         break;
1708                 pp_buffer_stderr(&pp, output_timeout);
1709                 pp_output(&pp);
1710                 code = pp_collect_finished(&pp);
1711                 if (code) {
1712                         pp.shutdown = 1;
1713                         if (code < 0)
1714                                 kill_children(&pp, -code);
1715                 }
1716         }
1717
1718         pp_cleanup(&pp);
1719         return 0;
1720 }