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