run-command.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "environment.h"
   4 #include "exec-cmd.h"
   5 #include "gettext.h"
   6 #include "sigchain.h"
   7 #include "strvec.h"
   8 #include "thread-utils.h"
   9 #include "strbuf.h"
  10 #include "string-list.h"
  11 #include "quote.h"
  12 #include "config.h"
  13 #include "packfile.h"
  14 #include "hook.h"
  15 #include "compat/nonblock.h"
  16
  17 void child_process_init(struct child_process *child)
  18 {
  19         struct child_process blank = CHILD_PROCESS_INIT;
  20         memcpy(child, &blank, sizeof(*child));
  21 }
  22
  23 void child_process_clear(struct child_process *child)
  24 {
  25         strvec_clear(&child->args);
  26         strvec_clear(&child->env);
  27 }
  28
  29 struct child_to_clean {
  30         pid_t pid;
  31         struct child_process *process;
  32         struct child_to_clean *next;
  33 };
  34 static struct child_to_clean *children_to_clean;
  35 static int installed_child_cleanup_handler;
  36
  37 static void cleanup_children(int sig, int in_signal)
  38 {
  39         struct child_to_clean *children_to_wait_for = NULL;
  40
  41         while (children_to_clean) {
  42                 struct child_to_clean *p = children_to_clean;
  43                 children_to_clean = p->next;
  44
  45                 if (p->process && !in_signal) {
  46                         struct child_process *process = p->process;
  47                         if (process->clean_on_exit_handler) {
  48                                 trace_printf(
  49                                         "trace: run_command: running exit handler for pid %"
  50                                         PRIuMAX, (uintmax_t)p->pid
  51                                 );
  52                                 process->clean_on_exit_handler(process);
  53                         }
  54                 }
  55
  56                 kill(p->pid, sig);
  57
  58                 if (p->process && p->process->wait_after_clean) {
  59                         p->next = children_to_wait_for;
  60                         children_to_wait_for = p;
  61                 } else {
  62                         if (!in_signal)
  63                                 free(p);
  64                 }
  65         }
  66
  67         while (children_to_wait_for) {
  68                 struct child_to_clean *p = children_to_wait_for;
  69                 children_to_wait_for = p->next;
  70
  71                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  72                         ; /* spin waiting for process exit or error */
  73
  74                 if (!in_signal)
  75                         free(p);
  76         }
  77 }
  78
  79 static void cleanup_children_on_signal(int sig)
  80 {
  81         cleanup_children(sig, 1);
  82         sigchain_pop(sig);
  83         raise(sig);
  84 }
  85
  86 static void cleanup_children_on_exit(void)
  87 {
  88         cleanup_children(SIGTERM, 0);
  89 }
  90
  91 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  92 {
  93         struct child_to_clean *p = xmalloc(sizeof(*p));
  94         p->pid = pid;
  95         p->process = process;
  96         p->next = children_to_clean;
  97         children_to_clean = p;
  98
  99         if (!installed_child_cleanup_handler) {
 100                 atexit(cleanup_children_on_exit);
 101                 sigchain_push_common(cleanup_children_on_signal);
 102                 installed_child_cleanup_handler = 1;
 103         }
 104 }
 105
 106 static void clear_child_for_cleanup(pid_t pid)
 107 {
 108         struct child_to_clean **pp;
 109
 110         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 111                 struct child_to_clean *clean_me = *pp;
 112
 113                 if (clean_me->pid == pid) {
 114                         *pp = clean_me->next;
 115                         free(clean_me);
 116                         return;
 117                 }
 118         }
 119 }
 120
 121 static inline void close_pair(int fd[2])
 122 {
 123         close(fd[0]);
 124         close(fd[1]);
 125 }
 126
 127 int is_executable(const char *name)
 128 {
 129         struct stat st;
 130
 131         if (stat(name, &st) || /* stat, not lstat */
 132             !S_ISREG(st.st_mode))
 133                 return 0;
 134
 135 #if defined(GIT_WINDOWS_NATIVE)
 136         /*
 137          * On Windows there is no executable bit. The file extension
 138          * indicates whether it can be run as an executable, and Git
 139          * has special-handling to detect scripts and launch them
 140          * through the indicated script interpreter. We test for the
 141          * file extension first because virus scanners may make
 142          * it quite expensive to open many files.
 143          */
 144         if (ends_with(name, ".exe"))
 145                 return S_IXUSR;
 146
 147 {
 148         /*
 149          * Now that we know it does not have an executable extension,
 150          * peek into the file instead.
 151          */
 152         char buf[3] = { 0 };
 153         int n;
 154         int fd = open(name, O_RDONLY);
 155         st.st_mode &= ~S_IXUSR;
 156         if (fd >= 0) {
 157                 n = read(fd, buf, 2);
 158                 if (n == 2)
 159                         /* look for a she-bang */
 160                         if (!strcmp(buf, "#!"))
 161                                 st.st_mode |= S_IXUSR;
 162                 close(fd);
 163         }
 164 }
 165 #endif
 166         return st.st_mode & S_IXUSR;
 167 }
 168
 169 /*
 170  * Search $PATH for a command.  This emulates the path search that
 171  * execvp would perform, without actually executing the command so it
 172  * can be used before fork() to prepare to run a command using
 173  * execve() or after execvp() to diagnose why it failed.
 174  *
 175  * The caller should ensure that file contains no directory
 176  * separators.
 177  *
 178  * Returns the path to the command, as found in $PATH or NULL if the
 179  * command could not be found.  The caller inherits ownership of the memory
 180  * used to store the resultant path.
 181  *
 182  * This should not be used on Windows, where the $PATH search rules
 183  * are more complicated (e.g., a search for "foo" should find
 184  * "foo.exe").
 185  */
 186 static char *locate_in_PATH(const char *file)
 187 {
 188         const char *p = getenv("PATH");
 189         struct strbuf buf = STRBUF_INIT;
 190
 191         if (!p || !*p)
 192                 return NULL;
 193
 194         while (1) {
 195                 const char *end = strchrnul(p, ':');
 196
 197                 strbuf_reset(&buf);
 198
 199                 /* POSIX specifies an empty entry as the current directory. */
 200                 if (end != p) {
 201                         strbuf_add(&buf, p, end - p);
 202                         strbuf_addch(&buf, '/');
 203                 }
 204                 strbuf_addstr(&buf, file);
 205
 206                 if (is_executable(buf.buf))
 207                         return strbuf_detach(&buf, NULL);
 208
 209                 if (!*end)
 210                         break;
 211                 p = end + 1;
 212         }
 213
 214         strbuf_release(&buf);
 215         return NULL;
 216 }
 217
 218 int exists_in_PATH(const char *command)
 219 {
 220         char *r = locate_in_PATH(command);
 221         int found = r != NULL;
 222         free(r);
 223         return found;
 224 }
 225
 226 int sane_execvp(const char *file, char * const argv[])
 227 {
 228 #ifndef GIT_WINDOWS_NATIVE
 229         /*
 230          * execvp() doesn't return, so we all we can do is tell trace2
 231          * what we are about to do and let it leave a hint in the log
 232          * (unless of course the execvp() fails).
 233          *
 234          * we skip this for Windows because the compat layer already
 235          * has to emulate the execvp() call anyway.
 236          */
 237         int exec_id = trace2_exec(file, (const char **)argv);
 238 #endif
 239
 240         if (!execvp(file, argv))
 241                 return 0; /* cannot happen ;-) */
 242
 243 #ifndef GIT_WINDOWS_NATIVE
 244         {
 245                 int ec = errno;
 246                 trace2_exec_result(exec_id, ec);
 247                 errno = ec;
 248         }
 249 #endif
 250
 251         /*
 252          * When a command can't be found because one of the directories
 253          * listed in $PATH is unsearchable, execvp reports EACCES, but
 254          * careful usability testing (read: analysis of occasional bug
 255          * reports) reveals that "No such file or directory" is more
 256          * intuitive.
 257          *
 258          * We avoid commands with "/", because execvp will not do $PATH
 259          * lookups in that case.
 260          *
 261          * The reassignment of EACCES to errno looks like a no-op below,
 262          * but we need to protect against exists_in_PATH overwriting errno.
 263          */
 264         if (errno == EACCES && !strchr(file, '/'))
 265                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 266         else if (errno == ENOTDIR && !strchr(file, '/'))
 267                 errno = ENOENT;
 268         return -1;
 269 }
 270
 271 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 272 {
 273         if (!argv[0])
 274                 BUG("shell command is empty");
 275
 276         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 277 #ifndef GIT_WINDOWS_NATIVE
 278                 strvec_push(out, SHELL_PATH);
 279 #else
 280                 strvec_push(out, "sh");
 281 #endif
 282                 strvec_push(out, "-c");
 283
 284                 /*
 285                  * If we have no extra arguments, we do not even need to
 286                  * bother with the "$@" magic.
 287                  */
 288                 if (!argv[1])
 289                         strvec_push(out, argv[0]);
 290                 else
 291                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 292         }
 293
 294         strvec_pushv(out, argv);
 295         return out->v;
 296 }
 297
 298 #ifndef GIT_WINDOWS_NATIVE
 299 static int child_notifier = -1;
 300
 301 enum child_errcode {
 302         CHILD_ERR_CHDIR,
 303         CHILD_ERR_DUP2,
 304         CHILD_ERR_CLOSE,
 305         CHILD_ERR_SIGPROCMASK,
 306         CHILD_ERR_ENOENT,
 307         CHILD_ERR_SILENT,
 308         CHILD_ERR_ERRNO
 309 };
 310
 311 struct child_err {
 312         enum child_errcode err;
 313         int syserr; /* errno */
 314 };
 315
 316 static void child_die(enum child_errcode err)
 317 {
 318         struct child_err buf;
 319
 320         buf.err = err;
 321         buf.syserr = errno;
 322
 323         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 324         xwrite(child_notifier, &buf, sizeof(buf));
 325         _exit(1);
 326 }
 327
 328 static void child_dup2(int fd, int to)
 329 {
 330         if (dup2(fd, to) < 0)
 331                 child_die(CHILD_ERR_DUP2);
 332 }
 333
 334 static void child_close(int fd)
 335 {
 336         if (close(fd))
 337                 child_die(CHILD_ERR_CLOSE);
 338 }
 339
 340 static void child_close_pair(int fd[2])
 341 {
 342         child_close(fd[0]);
 343         child_close(fd[1]);
 344 }
 345
 346 static void child_error_fn(const char *err UNUSED, va_list params UNUSED)
 347 {
 348         const char msg[] = "error() should not be called in child\n";
 349         xwrite(2, msg, sizeof(msg) - 1);
 350 }
 351
 352 static void child_warn_fn(const char *err UNUSED, va_list params UNUSED)
 353 {
 354         const char msg[] = "warn() should not be called in child\n";
 355         xwrite(2, msg, sizeof(msg) - 1);
 356 }
 357
 358 static void NORETURN child_die_fn(const char *err UNUSED, va_list params UNUSED)
 359 {
 360         const char msg[] = "die() should not be called in child\n";
 361         xwrite(2, msg, sizeof(msg) - 1);
 362         _exit(2);
 363 }
 364
 365 /* this runs in the parent process */
 366 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 367 {
 368         static void (*old_errfn)(const char *err, va_list params);
 369         report_fn die_message_routine = get_die_message_routine();
 370
 371         old_errfn = get_error_routine();
 372         set_error_routine(die_message_routine);
 373         errno = cerr->syserr;
 374
 375         switch (cerr->err) {
 376         case CHILD_ERR_CHDIR:
 377                 error_errno("exec '%s': cd to '%s' failed",
 378                             cmd->args.v[0], cmd->dir);
 379                 break;
 380         case CHILD_ERR_DUP2:
 381                 error_errno("dup2() in child failed");
 382                 break;
 383         case CHILD_ERR_CLOSE:
 384                 error_errno("close() in child failed");
 385                 break;
 386         case CHILD_ERR_SIGPROCMASK:
 387                 error_errno("sigprocmask failed restoring signals");
 388                 break;
 389         case CHILD_ERR_ENOENT:
 390                 error_errno("cannot run %s", cmd->args.v[0]);
 391                 break;
 392         case CHILD_ERR_SILENT:
 393                 break;
 394         case CHILD_ERR_ERRNO:
 395                 error_errno("cannot exec '%s'", cmd->args.v[0]);
 396                 break;
 397         }
 398         set_error_routine(old_errfn);
 399 }
 400
 401 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 402 {
 403         if (!cmd->args.v[0])
 404                 BUG("command is empty");
 405
 406         /*
 407          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 408          * attempt to interpret the command with 'sh'.
 409          */
 410         strvec_push(out, SHELL_PATH);
 411
 412         if (cmd->git_cmd) {
 413                 prepare_git_cmd(out, cmd->args.v);
 414         } else if (cmd->use_shell) {
 415                 prepare_shell_cmd(out, cmd->args.v);
 416         } else {
 417                 strvec_pushv(out, cmd->args.v);
 418         }
 419
 420         /*
 421          * If there are no dir separator characters in the command then perform
 422          * a path lookup and use the resolved path as the command to exec. If
 423          * there are dir separator characters, we have exec attempt to invoke
 424          * the command directly.
 425          */
 426         if (!has_dir_sep(out->v[1])) {
 427                 char *program = locate_in_PATH(out->v[1]);
 428                 if (program) {
 429                         free((char *)out->v[1]);
 430                         out->v[1] = program;
 431                 } else {
 432                         strvec_clear(out);
 433                         errno = ENOENT;
 434                         return -1;
 435                 }
 436         }
 437
 438         return 0;
 439 }
 440
 441 static char **prep_childenv(const char *const *deltaenv)
 442 {
 443         extern char **environ;
 444         char **childenv;
 445         struct string_list env = STRING_LIST_INIT_DUP;
 446         struct strbuf key = STRBUF_INIT;
 447         const char *const *p;
 448         int i;
 449
 450         /* Construct a sorted string list consisting of the current environ */
 451         for (p = (const char *const *) environ; p && *p; p++) {
 452                 const char *equals = strchr(*p, '=');
 453
 454                 if (equals) {
 455                         strbuf_reset(&key);
 456                         strbuf_add(&key, *p, equals - *p);
 457                         string_list_append(&env, key.buf)->util = (void *) *p;
 458                 } else {
 459                         string_list_append(&env, *p)->util = (void *) *p;
 460                 }
 461         }
 462         string_list_sort(&env);
 463
 464         /* Merge in 'deltaenv' with the current environ */
 465         for (p = deltaenv; p && *p; p++) {
 466                 const char *equals = strchr(*p, '=');
 467
 468                 if (equals) {
 469                         /* ('key=value'), insert or replace entry */
 470                         strbuf_reset(&key);
 471                         strbuf_add(&key, *p, equals - *p);
 472                         string_list_insert(&env, key.buf)->util = (void *) *p;
 473                 } else {
 474                         /* otherwise ('key') remove existing entry */
 475                         string_list_remove(&env, *p, 0);
 476                 }
 477         }
 478
 479         /* Create an array of 'char *' to be used as the childenv */
 480         ALLOC_ARRAY(childenv, env.nr + 1);
 481         for (i = 0; i < env.nr; i++)
 482                 childenv[i] = env.items[i].util;
 483         childenv[env.nr] = NULL;
 484
 485         string_list_clear(&env, 0);
 486         strbuf_release(&key);
 487         return childenv;
 488 }
 489
 490 struct atfork_state {
 491 #ifndef NO_PTHREADS
 492         int cs;
 493 #endif
 494         sigset_t old;
 495 };
 496
 497 #define CHECK_BUG(err, msg) \
 498         do { \
 499                 int e = (err); \
 500                 if (e) \
 501                         BUG("%s: %s", msg, strerror(e)); \
 502         } while(0)
 503
 504 static void atfork_prepare(struct atfork_state *as)
 505 {
 506         sigset_t all;
 507
 508         if (sigfillset(&all))
 509                 die_errno("sigfillset");
 510 #ifdef NO_PTHREADS
 511         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 512                 die_errno("sigprocmask");
 513 #else
 514         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 515                 "blocking all signals");
 516         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 517                 "disabling cancellation");
 518 #endif
 519 }
 520
 521 static void atfork_parent(struct atfork_state *as)
 522 {
 523 #ifdef NO_PTHREADS
 524         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 525                 die_errno("sigprocmask");
 526 #else
 527         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 528                 "re-enabling cancellation");
 529         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 530                 "restoring signal mask");
 531 #endif
 532 }
 533 #endif /* GIT_WINDOWS_NATIVE */
 534
 535 static inline void set_cloexec(int fd)
 536 {
 537         int flags = fcntl(fd, F_GETFD);
 538         if (flags >= 0)
 539                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 540 }
 541
 542 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 543 {
 544         int status, code = -1;
 545         pid_t waiting;
 546         int failed_errno = 0;
 547
 548         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 549                 ;       /* nothing */
 550
 551         if (waiting < 0) {
 552                 failed_errno = errno;
 553                 if (!in_signal)
 554                         error_errno("waitpid for %s failed", argv0);
 555         } else if (waiting != pid) {
 556                 if (!in_signal)
 557                         error("waitpid is confused (%s)", argv0);
 558         } else if (WIFSIGNALED(status)) {
 559                 code = WTERMSIG(status);
 560                 if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 561                         error("%s died of signal %d", argv0, code);
 562                 /*
 563                  * This return value is chosen so that code & 0xff
 564                  * mimics the exit code that a POSIX shell would report for
 565                  * a program that died from this signal.
 566                  */
 567                 code += 128;
 568         } else if (WIFEXITED(status)) {
 569                 code = WEXITSTATUS(status);
 570         } else {
 571                 if (!in_signal)
 572                         error("waitpid is confused (%s)", argv0);
 573         }
 574
 575         if (!in_signal)
 576                 clear_child_for_cleanup(pid);
 577
 578         errno = failed_errno;
 579         return code;
 580 }
 581
 582 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 583 {
 584         struct string_list envs = STRING_LIST_INIT_DUP;
 585         const char *const *e;
 586         int i;
 587         int printed_unset = 0;
 588
 589         /* Last one wins, see run-command.c:prep_childenv() for context */
 590         for (e = deltaenv; e && *e; e++) {
 591                 struct strbuf key = STRBUF_INIT;
 592                 char *equals = strchr(*e, '=');
 593
 594                 if (equals) {
 595                         strbuf_add(&key, *e, equals - *e);
 596                         string_list_insert(&envs, key.buf)->util = equals + 1;
 597                 } else {
 598                         string_list_insert(&envs, *e)->util = NULL;
 599                 }
 600                 strbuf_release(&key);
 601         }
 602
 603         /* "unset X Y...;" */
 604         for (i = 0; i < envs.nr; i++) {
 605                 const char *var = envs.items[i].string;
 606                 const char *val = envs.items[i].util;
 607
 608                 if (val || !getenv(var))
 609                         continue;
 610
 611                 if (!printed_unset) {
 612                         strbuf_addstr(dst, " unset");
 613                         printed_unset = 1;
 614                 }
 615                 strbuf_addf(dst, " %s", var);
 616         }
 617         if (printed_unset)
 618                 strbuf_addch(dst, ';');
 619
 620         /* ... followed by "A=B C=D ..." */
 621         for (i = 0; i < envs.nr; i++) {
 622                 const char *var = envs.items[i].string;
 623                 const char *val = envs.items[i].util;
 624                 const char *oldval;
 625
 626                 if (!val)
 627                         continue;
 628
 629                 oldval = getenv(var);
 630                 if (oldval && !strcmp(val, oldval))
 631                         continue;
 632
 633                 strbuf_addf(dst, " %s=", var);
 634                 sq_quote_buf_pretty(dst, val);
 635         }
 636         string_list_clear(&envs, 0);
 637 }
 638
 639 static void trace_run_command(const struct child_process *cp)
 640 {
 641         struct strbuf buf = STRBUF_INIT;
 642
 643         if (!trace_want(&trace_default_key))
 644                 return;
 645
 646         strbuf_addstr(&buf, "trace: run_command:");
 647         if (cp->dir) {
 648                 strbuf_addstr(&buf, " cd ");
 649                 sq_quote_buf_pretty(&buf, cp->dir);
 650                 strbuf_addch(&buf, ';');
 651         }
 652         trace_add_env(&buf, cp->env.v);
 653         if (cp->git_cmd)
 654                 strbuf_addstr(&buf, " git");
 655         sq_quote_argv_pretty(&buf, cp->args.v);
 656
 657         trace_printf("%s", buf.buf);
 658         strbuf_release(&buf);
 659 }
 660
 661 int start_command(struct child_process *cmd)
 662 {
 663         int need_in, need_out, need_err;
 664         int fdin[2], fdout[2], fderr[2];
 665         int failed_errno;
 666         char *str;
 667
 668         /*
 669          * In case of errors we must keep the promise to close FDs
 670          * that have been passed in via ->in and ->out.
 671          */
 672
 673         need_in = !cmd->no_stdin && cmd->in < 0;
 674         if (need_in) {
 675                 if (pipe(fdin) < 0) {
 676                         failed_errno = errno;
 677                         if (cmd->out > 0)
 678                                 close(cmd->out);
 679                         str = "standard input";
 680                         goto fail_pipe;
 681                 }
 682                 cmd->in = fdin[1];
 683         }
 684
 685         need_out = !cmd->no_stdout
 686                 && !cmd->stdout_to_stderr
 687                 && cmd->out < 0;
 688         if (need_out) {
 689                 if (pipe(fdout) < 0) {
 690                         failed_errno = errno;
 691                         if (need_in)
 692                                 close_pair(fdin);
 693                         else if (cmd->in)
 694                                 close(cmd->in);
 695                         str = "standard output";
 696                         goto fail_pipe;
 697                 }
 698                 cmd->out = fdout[0];
 699         }
 700
 701         need_err = !cmd->no_stderr && cmd->err < 0;
 702         if (need_err) {
 703                 if (pipe(fderr) < 0) {
 704                         failed_errno = errno;
 705                         if (need_in)
 706                                 close_pair(fdin);
 707                         else if (cmd->in)
 708                                 close(cmd->in);
 709                         if (need_out)
 710                                 close_pair(fdout);
 711                         else if (cmd->out)
 712                                 close(cmd->out);
 713                         str = "standard error";
 714 fail_pipe:
 715                         error("cannot create %s pipe for %s: %s",
 716                                 str, cmd->args.v[0], strerror(failed_errno));
 717                         child_process_clear(cmd);
 718                         errno = failed_errno;
 719                         return -1;
 720                 }
 721                 cmd->err = fderr[0];
 722         }
 723
 724         trace2_child_start(cmd);
 725         trace_run_command(cmd);
 726
 727         fflush(NULL);
 728
 729         if (cmd->close_object_store)
 730                 close_object_store(the_repository->objects);
 731
 732 #ifndef GIT_WINDOWS_NATIVE
 733 {
 734         int notify_pipe[2];
 735         int null_fd = -1;
 736         char **childenv;
 737         struct strvec argv = STRVEC_INIT;
 738         struct child_err cerr;
 739         struct atfork_state as;
 740
 741         if (prepare_cmd(&argv, cmd) < 0) {
 742                 failed_errno = errno;
 743                 cmd->pid = -1;
 744                 if (!cmd->silent_exec_failure)
 745                         error_errno("cannot run %s", cmd->args.v[0]);
 746                 goto end_of_spawn;
 747         }
 748
 749         if (pipe(notify_pipe))
 750                 notify_pipe[0] = notify_pipe[1] = -1;
 751
 752         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 753                 null_fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
 754                 set_cloexec(null_fd);
 755         }
 756
 757         childenv = prep_childenv(cmd->env.v);
 758         atfork_prepare(&as);
 759
 760         /*
 761          * NOTE: In order to prevent deadlocking when using threads special
 762          * care should be taken with the function calls made in between the
 763          * fork() and exec() calls.  No calls should be made to functions which
 764          * require acquiring a lock (e.g. malloc) as the lock could have been
 765          * held by another thread at the time of forking, causing the lock to
 766          * never be released in the child process.  This means only
 767          * Async-Signal-Safe functions are permitted in the child.
 768          */
 769         cmd->pid = fork();
 770         failed_errno = errno;
 771         if (!cmd->pid) {
 772                 int sig;
 773                 /*
 774                  * Ensure the default die/error/warn routines do not get
 775                  * called, they can take stdio locks and malloc.
 776                  */
 777                 set_die_routine(child_die_fn);
 778                 set_error_routine(child_error_fn);
 779                 set_warn_routine(child_warn_fn);
 780
 781                 close(notify_pipe[0]);
 782                 set_cloexec(notify_pipe[1]);
 783                 child_notifier = notify_pipe[1];
 784
 785                 if (cmd->no_stdin)
 786                         child_dup2(null_fd, 0);
 787                 else if (need_in) {
 788                         child_dup2(fdin[0], 0);
 789                         child_close_pair(fdin);
 790                 } else if (cmd->in) {
 791                         child_dup2(cmd->in, 0);
 792                         child_close(cmd->in);
 793                 }
 794
 795                 if (cmd->no_stderr)
 796                         child_dup2(null_fd, 2);
 797                 else if (need_err) {
 798                         child_dup2(fderr[1], 2);
 799                         child_close_pair(fderr);
 800                 } else if (cmd->err > 1) {
 801                         child_dup2(cmd->err, 2);
 802                         child_close(cmd->err);
 803                 }
 804
 805                 if (cmd->no_stdout)
 806                         child_dup2(null_fd, 1);
 807                 else if (cmd->stdout_to_stderr)
 808                         child_dup2(2, 1);
 809                 else if (need_out) {
 810                         child_dup2(fdout[1], 1);
 811                         child_close_pair(fdout);
 812                 } else if (cmd->out > 1) {
 813                         child_dup2(cmd->out, 1);
 814                         child_close(cmd->out);
 815                 }
 816
 817                 if (cmd->dir && chdir(cmd->dir))
 818                         child_die(CHILD_ERR_CHDIR);
 819
 820                 /*
 821                  * restore default signal handlers here, in case
 822                  * we catch a signal right before execve below
 823                  */
 824                 for (sig = 1; sig < NSIG; sig++) {
 825                         /* ignored signals get reset to SIG_DFL on execve */
 826                         if (signal(sig, SIG_DFL) == SIG_IGN)
 827                                 signal(sig, SIG_IGN);
 828                 }
 829
 830                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 831                         child_die(CHILD_ERR_SIGPROCMASK);
 832
 833                 /*
 834                  * Attempt to exec using the command and arguments starting at
 835                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 836                  * be used in the event exec failed with ENOEXEC at which point
 837                  * we will try to interpret the command using 'sh'.
 838                  */
 839                 execve(argv.v[1], (char *const *) argv.v + 1,
 840                        (char *const *) childenv);
 841                 if (errno == ENOEXEC)
 842                         execve(argv.v[0], (char *const *) argv.v,
 843                                (char *const *) childenv);
 844
 845                 if (errno == ENOENT) {
 846                         if (cmd->silent_exec_failure)
 847                                 child_die(CHILD_ERR_SILENT);
 848                         child_die(CHILD_ERR_ENOENT);
 849                 } else {
 850                         child_die(CHILD_ERR_ERRNO);
 851                 }
 852         }
 853         atfork_parent(&as);
 854         if (cmd->pid < 0)
 855                 error_errno("cannot fork() for %s", cmd->args.v[0]);
 856         else if (cmd->clean_on_exit)
 857                 mark_child_for_cleanup(cmd->pid, cmd);
 858
 859         /*
 860          * Wait for child's exec. If the exec succeeds (or if fork()
 861          * failed), EOF is seen immediately by the parent. Otherwise, the
 862          * child process sends a child_err struct.
 863          * Note that use of this infrastructure is completely advisory,
 864          * therefore, we keep error checks minimal.
 865          */
 866         close(notify_pipe[1]);
 867         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 868                 /*
 869                  * At this point we know that fork() succeeded, but exec()
 870                  * failed. Errors have been reported to our stderr.
 871                  */
 872                 wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 873                 child_err_spew(cmd, &cerr);
 874                 failed_errno = errno;
 875                 cmd->pid = -1;
 876         }
 877         close(notify_pipe[0]);
 878
 879         if (null_fd >= 0)
 880                 close(null_fd);
 881         strvec_clear(&argv);
 882         free(childenv);
 883 }
 884 end_of_spawn:
 885
 886 #else
 887 {
 888         int fhin = 0, fhout = 1, fherr = 2;
 889         const char **sargv = cmd->args.v;
 890         struct strvec nargv = STRVEC_INIT;
 891
 892         if (cmd->no_stdin)
 893                 fhin = open("/dev/null", O_RDWR);
 894         else if (need_in)
 895                 fhin = dup(fdin[0]);
 896         else if (cmd->in)
 897                 fhin = dup(cmd->in);
 898
 899         if (cmd->no_stderr)
 900                 fherr = open("/dev/null", O_RDWR);
 901         else if (need_err)
 902                 fherr = dup(fderr[1]);
 903         else if (cmd->err > 2)
 904                 fherr = dup(cmd->err);
 905
 906         if (cmd->no_stdout)
 907                 fhout = open("/dev/null", O_RDWR);
 908         else if (cmd->stdout_to_stderr)
 909                 fhout = dup(fherr);
 910         else if (need_out)
 911                 fhout = dup(fdout[1]);
 912         else if (cmd->out > 1)
 913                 fhout = dup(cmd->out);
 914
 915         if (cmd->git_cmd)
 916                 cmd->args.v = prepare_git_cmd(&nargv, sargv);
 917         else if (cmd->use_shell)
 918                 cmd->args.v = prepare_shell_cmd(&nargv, sargv);
 919
 920         cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v,
 921                                   (char**) cmd->env.v,
 922                                   cmd->dir, fhin, fhout, fherr);
 923         failed_errno = errno;
 924         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 925                 error_errno("cannot spawn %s", cmd->args.v[0]);
 926         if (cmd->clean_on_exit && cmd->pid >= 0)
 927                 mark_child_for_cleanup(cmd->pid, cmd);
 928
 929         strvec_clear(&nargv);
 930         cmd->args.v = sargv;
 931         if (fhin != 0)
 932                 close(fhin);
 933         if (fhout != 1)
 934                 close(fhout);
 935         if (fherr != 2)
 936                 close(fherr);
 937 }
 938 #endif
 939
 940         if (cmd->pid < 0) {
 941                 trace2_child_exit(cmd, -1);
 942
 943                 if (need_in)
 944                         close_pair(fdin);
 945                 else if (cmd->in)
 946                         close(cmd->in);
 947                 if (need_out)
 948                         close_pair(fdout);
 949                 else if (cmd->out)
 950                         close(cmd->out);
 951                 if (need_err)
 952                         close_pair(fderr);
 953                 else if (cmd->err)
 954                         close(cmd->err);
 955                 child_process_clear(cmd);
 956                 errno = failed_errno;
 957                 return -1;
 958         }
 959
 960         if (need_in)
 961                 close(fdin[0]);
 962         else if (cmd->in)
 963                 close(cmd->in);
 964
 965         if (need_out)
 966                 close(fdout[1]);
 967         else if (cmd->out)
 968                 close(cmd->out);
 969
 970         if (need_err)
 971                 close(fderr[1]);
 972         else if (cmd->err)
 973                 close(cmd->err);
 974
 975         return 0;
 976 }
 977
 978 int finish_command(struct child_process *cmd)
 979 {
 980         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 981         trace2_child_exit(cmd, ret);
 982         child_process_clear(cmd);
 983         invalidate_lstat_cache();
 984         return ret;
 985 }
 986
 987 int finish_command_in_signal(struct child_process *cmd)
 988 {
 989         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
 990         if (ret != -1)
 991                 trace2_child_exit(cmd, ret);
 992         return ret;
 993 }
 994
 995
 996 int run_command(struct child_process *cmd)
 997 {
 998         int code;
 999
1000         if (cmd->out < 0 || cmd->err < 0)
1001                 BUG("run_command with a pipe can cause deadlock");
1002
1003         code = start_command(cmd);
1004         if (code)
1005                 return code;
1006         return finish_command(cmd);
1007 }
1008
1009 #ifndef NO_PTHREADS
1010 static pthread_t main_thread;
1011 static int main_thread_set;
1012 static pthread_key_t async_key;
1013 static pthread_key_t async_die_counter;
1014
1015 static void *run_thread(void *data)
1016 {
1017         struct async *async = data;
1018         intptr_t ret;
1019
1020         if (async->isolate_sigpipe) {
1021                 sigset_t mask;
1022                 sigemptyset(&mask);
1023                 sigaddset(&mask, SIGPIPE);
1024                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL)) {
1025                         ret = error("unable to block SIGPIPE in async thread");
1026                         return (void *)ret;
1027                 }
1028         }
1029
1030         pthread_setspecific(async_key, async);
1031         ret = async->proc(async->proc_in, async->proc_out, async->data);
1032         return (void *)ret;
1033 }
1034
1035 static NORETURN void die_async(const char *err, va_list params)
1036 {
1037         report_fn die_message_fn = get_die_message_routine();
1038
1039         die_message_fn(err, params);
1040
1041         if (in_async()) {
1042                 struct async *async = pthread_getspecific(async_key);
1043                 if (async->proc_in >= 0)
1044                         close(async->proc_in);
1045                 if (async->proc_out >= 0)
1046                         close(async->proc_out);
1047                 pthread_exit((void *)128);
1048         }
1049
1050         exit(128);
1051 }
1052
1053 static int async_die_is_recursing(void)
1054 {
1055         void *ret = pthread_getspecific(async_die_counter);
1056         pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
1057         return ret != NULL;
1058 }
1059
1060 int in_async(void)
1061 {
1062         if (!main_thread_set)
1063                 return 0; /* no asyncs started yet */
1064         return !pthread_equal(main_thread, pthread_self());
1065 }
1066
1067 static void NORETURN async_exit(int code)
1068 {
1069         pthread_exit((void *)(intptr_t)code);
1070 }
1071
1072 #else
1073
1074 static struct {
1075         void (**handlers)(void);
1076         size_t nr;
1077         size_t alloc;
1078 } git_atexit_hdlrs;
1079
1080 static int git_atexit_installed;
1081
1082 static void git_atexit_dispatch(void)
1083 {
1084         size_t i;
1085
1086         for (i=git_atexit_hdlrs.nr ; i ; i--)
1087                 git_atexit_hdlrs.handlers[i-1]();
1088 }
1089
1090 static void git_atexit_clear(void)
1091 {
1092         free(git_atexit_hdlrs.handlers);
1093         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1094         git_atexit_installed = 0;
1095 }
1096
1097 #undef atexit
1098 int git_atexit(void (*handler)(void))
1099 {
1100         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1101         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1102         if (!git_atexit_installed) {
1103                 if (atexit(&git_atexit_dispatch))
1104                         return -1;
1105                 git_atexit_installed = 1;
1106         }
1107         return 0;
1108 }
1109 #define atexit git_atexit
1110
1111 static int process_is_async;
1112 int in_async(void)
1113 {
1114         return process_is_async;
1115 }
1116
1117 static void NORETURN async_exit(int code)
1118 {
1119         exit(code);
1120 }
1121
1122 #endif
1123
1124 void check_pipe(int err)
1125 {
1126         if (err == EPIPE) {
1127                 if (in_async())
1128                         async_exit(141);
1129
1130                 signal(SIGPIPE, SIG_DFL);
1131                 raise(SIGPIPE);
1132                 /* Should never happen, but just in case... */
1133                 exit(141);
1134         }
1135 }
1136
1137 int start_async(struct async *async)
1138 {
1139         int need_in, need_out;
1140         int fdin[2], fdout[2];
1141         int proc_in, proc_out;
1142
1143         need_in = async->in < 0;
1144         if (need_in) {
1145                 if (pipe(fdin) < 0) {
1146                         if (async->out > 0)
1147                                 close(async->out);
1148                         return error_errno("cannot create pipe");
1149                 }
1150                 async->in = fdin[1];
1151         }
1152
1153         need_out = async->out < 0;
1154         if (need_out) {
1155                 if (pipe(fdout) < 0) {
1156                         if (need_in)
1157                                 close_pair(fdin);
1158                         else if (async->in)
1159                                 close(async->in);
1160                         return error_errno("cannot create pipe");
1161                 }
1162                 async->out = fdout[0];
1163         }
1164
1165         if (need_in)
1166                 proc_in = fdin[0];
1167         else if (async->in)
1168                 proc_in = async->in;
1169         else
1170                 proc_in = -1;
1171
1172         if (need_out)
1173                 proc_out = fdout[1];
1174         else if (async->out)
1175                 proc_out = async->out;
1176         else
1177                 proc_out = -1;
1178
1179 #ifdef NO_PTHREADS
1180         /* Flush stdio before fork() to avoid cloning buffers */
1181         fflush(NULL);
1182
1183         async->pid = fork();
1184         if (async->pid < 0) {
1185                 error_errno("fork (async) failed");
1186                 goto error;
1187         }
1188         if (!async->pid) {
1189                 if (need_in)
1190                         close(fdin[1]);
1191                 if (need_out)
1192                         close(fdout[0]);
1193                 git_atexit_clear();
1194                 process_is_async = 1;
1195                 exit(!!async->proc(proc_in, proc_out, async->data));
1196         }
1197
1198         mark_child_for_cleanup(async->pid, NULL);
1199
1200         if (need_in)
1201                 close(fdin[0]);
1202         else if (async->in)
1203                 close(async->in);
1204
1205         if (need_out)
1206                 close(fdout[1]);
1207         else if (async->out)
1208                 close(async->out);
1209 #else
1210         if (!main_thread_set) {
1211                 /*
1212                  * We assume that the first time that start_async is called
1213                  * it is from the main thread.
1214                  */
1215                 main_thread_set = 1;
1216                 main_thread = pthread_self();
1217                 pthread_key_create(&async_key, NULL);
1218                 pthread_key_create(&async_die_counter, NULL);
1219                 set_die_routine(die_async);
1220                 set_die_is_recursing_routine(async_die_is_recursing);
1221         }
1222
1223         if (proc_in >= 0)
1224                 set_cloexec(proc_in);
1225         if (proc_out >= 0)
1226                 set_cloexec(proc_out);
1227         async->proc_in = proc_in;
1228         async->proc_out = proc_out;
1229         {
1230                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1231                 if (err) {
1232                         error(_("cannot create async thread: %s"), strerror(err));
1233                         goto error;
1234                 }
1235         }
1236 #endif
1237         return 0;
1238
1239 error:
1240         if (need_in)
1241                 close_pair(fdin);
1242         else if (async->in)
1243                 close(async->in);
1244
1245         if (need_out)
1246                 close_pair(fdout);
1247         else if (async->out)
1248                 close(async->out);
1249         return -1;
1250 }
1251
1252 int finish_async(struct async *async)
1253 {
1254 #ifdef NO_PTHREADS
1255         int ret = wait_or_whine(async->pid, "child process", 0);
1256
1257         invalidate_lstat_cache();
1258
1259         return ret;
1260 #else
1261         void *ret = (void *)(intptr_t)(-1);
1262
1263         if (pthread_join(async->tid, &ret))
1264                 error("pthread_join failed");
1265         invalidate_lstat_cache();
1266         return (int)(intptr_t)ret;
1267
1268 #endif
1269 }
1270
1271 int async_with_fork(void)
1272 {
1273 #ifdef NO_PTHREADS
1274         return 1;
1275 #else
1276         return 0;
1277 #endif
1278 }
1279
1280 struct io_pump {
1281         /* initialized by caller */
1282         int fd;
1283         int type; /* POLLOUT or POLLIN */
1284         union {
1285                 struct {
1286                         const char *buf;
1287                         size_t len;
1288                 } out;
1289                 struct {
1290                         struct strbuf *buf;
1291                         size_t hint;
1292                 } in;
1293         } u;
1294
1295         /* returned by pump_io */
1296         int error; /* 0 for success, otherwise errno */
1297
1298         /* internal use */
1299         struct pollfd *pfd;
1300 };
1301
1302 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1303 {
1304         int pollsize = 0;
1305         int i;
1306
1307         for (i = 0; i < nr; i++) {
1308                 struct io_pump *io = &slots[i];
1309                 if (io->fd < 0)
1310                         continue;
1311                 pfd[pollsize].fd = io->fd;
1312                 pfd[pollsize].events = io->type;
1313                 io->pfd = &pfd[pollsize++];
1314         }
1315
1316         if (!pollsize)
1317                 return 0;
1318
1319         if (poll(pfd, pollsize, -1) < 0) {
1320                 if (errno == EINTR)
1321                         return 1;
1322                 die_errno("poll failed");
1323         }
1324
1325         for (i = 0; i < nr; i++) {
1326                 struct io_pump *io = &slots[i];
1327
1328                 if (io->fd < 0)
1329                         continue;
1330
1331                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1332                         continue;
1333
1334                 if (io->type == POLLOUT) {
1335                         ssize_t len;
1336
1337                         /*
1338                          * Don't use xwrite() here. It loops forever on EAGAIN,
1339                          * and we're in our own poll() loop here.
1340                          *
1341                          * Note that we lose xwrite()'s handling of MAX_IO_SIZE
1342                          * and EINTR, so we have to implement those ourselves.
1343                          */
1344                         len = write(io->fd, io->u.out.buf,
1345                                     io->u.out.len <= MAX_IO_SIZE ?
1346                                     io->u.out.len : MAX_IO_SIZE);
1347                         if (len < 0) {
1348                                 if (errno != EINTR && errno != EAGAIN &&
1349                                     errno != ENOSPC) {
1350                                         io->error = errno;
1351                                         close(io->fd);
1352                                         io->fd = -1;
1353                                 }
1354                         } else {
1355                                 io->u.out.buf += len;
1356                                 io->u.out.len -= len;
1357                                 if (!io->u.out.len) {
1358                                         close(io->fd);
1359                                         io->fd = -1;
1360                                 }
1361                         }
1362                 }
1363
1364                 if (io->type == POLLIN) {
1365                         ssize_t len = strbuf_read_once(io->u.in.buf,
1366                                                        io->fd, io->u.in.hint);
1367                         if (len < 0)
1368                                 io->error = errno;
1369                         if (len <= 0) {
1370                                 close(io->fd);
1371                                 io->fd = -1;
1372                         }
1373                 }
1374         }
1375
1376         return 1;
1377 }
1378
1379 static int pump_io(struct io_pump *slots, int nr)
1380 {
1381         struct pollfd *pfd;
1382         int i;
1383
1384         for (i = 0; i < nr; i++)
1385                 slots[i].error = 0;
1386
1387         ALLOC_ARRAY(pfd, nr);
1388         while (pump_io_round(slots, nr, pfd))
1389                 ; /* nothing */
1390         free(pfd);
1391
1392         /* There may be multiple errno values, so just pick the first. */
1393         for (i = 0; i < nr; i++) {
1394                 if (slots[i].error) {
1395                         errno = slots[i].error;
1396                         return -1;
1397                 }
1398         }
1399         return 0;
1400 }
1401
1402
1403 int pipe_command(struct child_process *cmd,
1404                  const char *in, size_t in_len,
1405                  struct strbuf *out, size_t out_hint,
1406                  struct strbuf *err, size_t err_hint)
1407 {
1408         struct io_pump io[3];
1409         int nr = 0;
1410
1411         if (in)
1412                 cmd->in = -1;
1413         if (out)
1414                 cmd->out = -1;
1415         if (err)
1416                 cmd->err = -1;
1417
1418         if (start_command(cmd) < 0)
1419                 return -1;
1420
1421         if (in) {
1422                 if (enable_pipe_nonblock(cmd->in) < 0) {
1423                         error_errno("unable to make pipe non-blocking");
1424                         close(cmd->in);
1425                         if (out)
1426                                 close(cmd->out);
1427                         if (err)
1428                                 close(cmd->err);
1429                         return -1;
1430                 }
1431                 io[nr].fd = cmd->in;
1432                 io[nr].type = POLLOUT;
1433                 io[nr].u.out.buf = in;
1434                 io[nr].u.out.len = in_len;
1435                 nr++;
1436         }
1437         if (out) {
1438                 io[nr].fd = cmd->out;
1439                 io[nr].type = POLLIN;
1440                 io[nr].u.in.buf = out;
1441                 io[nr].u.in.hint = out_hint;
1442                 nr++;
1443         }
1444         if (err) {
1445                 io[nr].fd = cmd->err;
1446                 io[nr].type = POLLIN;
1447                 io[nr].u.in.buf = err;
1448                 io[nr].u.in.hint = err_hint;
1449                 nr++;
1450         }
1451
1452         if (pump_io(io, nr) < 0) {
1453                 finish_command(cmd); /* throw away exit code */
1454                 return -1;
1455         }
1456
1457         return finish_command(cmd);
1458 }
1459
1460 enum child_state {
1461         GIT_CP_FREE,
1462         GIT_CP_WORKING,
1463         GIT_CP_WAIT_CLEANUP,
1464 };
1465
1466 struct parallel_processes {
1467         size_t nr_processes;
1468
1469         struct {
1470                 enum child_state state;
1471                 struct child_process process;
1472                 struct strbuf err;
1473                 void *data;
1474         } *children;
1475         /*
1476          * The struct pollfd is logically part of *children,
1477          * but the system call expects it as its own array.
1478          */
1479         struct pollfd *pfd;
1480
1481         unsigned shutdown : 1;
1482
1483         size_t output_owner;
1484         struct strbuf buffered_output; /* of finished children */
1485 };
1486
1487 struct parallel_processes_for_signal {
1488         const struct run_process_parallel_opts *opts;
1489         const struct parallel_processes *pp;
1490 };
1491
1492 static void kill_children(const struct parallel_processes *pp,
1493                           const struct run_process_parallel_opts *opts,
1494                           int signo)
1495 {
1496         for (size_t i = 0; i < opts->processes; i++)
1497                 if (pp->children[i].state == GIT_CP_WORKING)
1498                         kill(pp->children[i].process.pid, signo);
1499 }
1500
1501 static void kill_children_signal(const struct parallel_processes_for_signal *pp_sig,
1502                                  int signo)
1503 {
1504         kill_children(pp_sig->pp, pp_sig->opts, signo);
1505 }
1506
1507 static struct parallel_processes_for_signal *pp_for_signal;
1508
1509 static void handle_children_on_signal(int signo)
1510 {
1511         kill_children_signal(pp_for_signal, signo);
1512         sigchain_pop(signo);
1513         raise(signo);
1514 }
1515
1516 static void pp_init(struct parallel_processes *pp,
1517                     const struct run_process_parallel_opts *opts,
1518                     struct parallel_processes_for_signal *pp_sig)
1519 {
1520         const size_t n = opts->processes;
1521
1522         if (!n)
1523                 BUG("you must provide a non-zero number of processes!");
1524
1525         trace_printf("run_processes_parallel: preparing to run up to %"PRIuMAX" tasks",
1526                      (uintmax_t)n);
1527
1528         if (!opts->get_next_task)
1529                 BUG("you need to specify a get_next_task function");
1530
1531         CALLOC_ARRAY(pp->children, n);
1532         if (!opts->ungroup)
1533                 CALLOC_ARRAY(pp->pfd, n);
1534
1535         for (size_t i = 0; i < n; i++) {
1536                 strbuf_init(&pp->children[i].err, 0);
1537                 child_process_init(&pp->children[i].process);
1538                 if (pp->pfd) {
1539                         pp->pfd[i].events = POLLIN | POLLHUP;
1540                         pp->pfd[i].fd = -1;
1541                 }
1542         }
1543
1544         pp_sig->pp = pp;
1545         pp_sig->opts = opts;
1546         pp_for_signal = pp_sig;
1547         sigchain_push_common(handle_children_on_signal);
1548 }
1549
1550 static void pp_cleanup(struct parallel_processes *pp,
1551                        const struct run_process_parallel_opts *opts)
1552 {
1553         trace_printf("run_processes_parallel: done");
1554         for (size_t i = 0; i < opts->processes; i++) {
1555                 strbuf_release(&pp->children[i].err);
1556                 child_process_clear(&pp->children[i].process);
1557         }
1558
1559         free(pp->children);
1560         free(pp->pfd);
1561
1562         /*
1563          * When get_next_task added messages to the buffer in its last
1564          * iteration, the buffered output is non empty.
1565          */
1566         strbuf_write(&pp->buffered_output, stderr);
1567         strbuf_release(&pp->buffered_output);
1568
1569         sigchain_pop_common();
1570 }
1571
1572 /* returns
1573  *  0 if a new task was started.
1574  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1575  *    problem with starting a new command)
1576  * <0 no new job was started, user wishes to shutdown early. Use negative code
1577  *    to signal the children.
1578  */
1579 static int pp_start_one(struct parallel_processes *pp,
1580                         const struct run_process_parallel_opts *opts)
1581 {
1582         size_t i;
1583         int code;
1584
1585         for (i = 0; i < opts->processes; i++)
1586                 if (pp->children[i].state == GIT_CP_FREE)
1587                         break;
1588         if (i == opts->processes)
1589                 BUG("bookkeeping is hard");
1590
1591         /*
1592          * By default, do not inherit stdin from the parent process - otherwise,
1593          * all children would share stdin! Users may overwrite this to provide
1594          * something to the child's stdin by having their 'get_next_task'
1595          * callback assign 0 to .no_stdin and an appropriate integer to .in.
1596          */
1597         pp->children[i].process.no_stdin = 1;
1598
1599         code = opts->get_next_task(&pp->children[i].process,
1600                                    opts->ungroup ? NULL : &pp->children[i].err,
1601                                    opts->data,
1602                                    &pp->children[i].data);
1603         if (!code) {
1604                 if (!opts->ungroup) {
1605                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1606                         strbuf_reset(&pp->children[i].err);
1607                 }
1608                 return 1;
1609         }
1610         if (!opts->ungroup) {
1611                 pp->children[i].process.err = -1;
1612                 pp->children[i].process.stdout_to_stderr = 1;
1613         }
1614
1615         if (start_command(&pp->children[i].process)) {
1616                 if (opts->start_failure)
1617                         code = opts->start_failure(opts->ungroup ? NULL :
1618                                                    &pp->children[i].err,
1619                                                    opts->data,
1620                                                    pp->children[i].data);
1621                 else
1622                         code = 0;
1623
1624                 if (!opts->ungroup) {
1625                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1626                         strbuf_reset(&pp->children[i].err);
1627                 }
1628                 if (code)
1629                         pp->shutdown = 1;
1630                 return code;
1631         }
1632
1633         pp->nr_processes++;
1634         pp->children[i].state = GIT_CP_WORKING;
1635         if (pp->pfd)
1636                 pp->pfd[i].fd = pp->children[i].process.err;
1637         return 0;
1638 }
1639
1640 static void pp_buffer_stderr(struct parallel_processes *pp,
1641                              const struct run_process_parallel_opts *opts,
1642                              int output_timeout)
1643 {
1644         while (poll(pp->pfd, opts->processes, output_timeout) < 0) {
1645                 if (errno == EINTR)
1646                         continue;
1647                 pp_cleanup(pp, opts);
1648                 die_errno("poll");
1649         }
1650
1651         /* Buffer output from all pipes. */
1652         for (size_t i = 0; i < opts->processes; i++) {
1653                 if (pp->children[i].state == GIT_CP_WORKING &&
1654                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1655                         int n = strbuf_read_once(&pp->children[i].err,
1656                                                  pp->children[i].process.err, 0);
1657                         if (n == 0) {
1658                                 close(pp->children[i].process.err);
1659                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1660                         } else if (n < 0)
1661                                 if (errno != EAGAIN)
1662                                         die_errno("read");
1663                 }
1664         }
1665 }
1666
1667 static void pp_output(const struct parallel_processes *pp)
1668 {
1669         size_t i = pp->output_owner;
1670
1671         if (pp->children[i].state == GIT_CP_WORKING &&
1672             pp->children[i].err.len) {
1673                 strbuf_write(&pp->children[i].err, stderr);
1674                 strbuf_reset(&pp->children[i].err);
1675         }
1676 }
1677
1678 static int pp_collect_finished(struct parallel_processes *pp,
1679                                const struct run_process_parallel_opts *opts)
1680 {
1681         int code;
1682         size_t i;
1683         int result = 0;
1684
1685         while (pp->nr_processes > 0) {
1686                 for (i = 0; i < opts->processes; i++)
1687                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1688                                 break;
1689                 if (i == opts->processes)
1690                         break;
1691
1692                 code = finish_command(&pp->children[i].process);
1693
1694                 if (opts->task_finished)
1695                         code = opts->task_finished(code, opts->ungroup ? NULL :
1696                                                    &pp->children[i].err, opts->data,
1697                                                    pp->children[i].data);
1698                 else
1699                         code = 0;
1700
1701                 if (code)
1702                         result = code;
1703                 if (code < 0)
1704                         break;
1705
1706                 pp->nr_processes--;
1707                 pp->children[i].state = GIT_CP_FREE;
1708                 if (pp->pfd)
1709                         pp->pfd[i].fd = -1;
1710                 child_process_init(&pp->children[i].process);
1711
1712                 if (opts->ungroup) {
1713                         ; /* no strbuf_*() work to do here */
1714                 } else if (i != pp->output_owner) {
1715                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1716                         strbuf_reset(&pp->children[i].err);
1717                 } else {
1718                         const size_t n = opts->processes;
1719
1720                         strbuf_write(&pp->children[i].err, stderr);
1721                         strbuf_reset(&pp->children[i].err);
1722
1723                         /* Output all other finished child processes */
1724                         strbuf_write(&pp->buffered_output, stderr);
1725                         strbuf_reset(&pp->buffered_output);
1726
1727                         /*
1728                          * Pick next process to output live.
1729                          * NEEDSWORK:
1730                          * For now we pick it randomly by doing a round
1731                          * robin. Later we may want to pick the one with
1732                          * the most output or the longest or shortest
1733                          * running process time.
1734                          */
1735                         for (i = 0; i < n; i++)
1736                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1737                                         break;
1738                         pp->output_owner = (pp->output_owner + i) % n;
1739                 }
1740         }
1741         return result;
1742 }
1743
1744 void run_processes_parallel(const struct run_process_parallel_opts *opts)
1745 {
1746         int i, code;
1747         int output_timeout = 100;
1748         int spawn_cap = 4;
1749         struct parallel_processes_for_signal pp_sig;
1750         struct parallel_processes pp = {
1751                 .buffered_output = STRBUF_INIT,
1752         };
1753         /* options */
1754         const char *tr2_category = opts->tr2_category;
1755         const char *tr2_label = opts->tr2_label;
1756         const int do_trace2 = tr2_category && tr2_label;
1757
1758         if (do_trace2)
1759                 trace2_region_enter_printf(tr2_category, tr2_label, NULL,
1760                                            "max:%d", opts->processes);
1761
1762         pp_init(&pp, opts, &pp_sig);
1763         while (1) {
1764                 for (i = 0;
1765                     i < spawn_cap && !pp.shutdown &&
1766                     pp.nr_processes < opts->processes;
1767                     i++) {
1768                         code = pp_start_one(&pp, opts);
1769                         if (!code)
1770                                 continue;
1771                         if (code < 0) {
1772                                 pp.shutdown = 1;
1773                                 kill_children(&pp, opts, -code);
1774                         }
1775                         break;
1776                 }
1777                 if (!pp.nr_processes)
1778                         break;
1779                 if (opts->ungroup) {
1780                         for (size_t i = 0; i < opts->processes; i++)
1781                                 pp.children[i].state = GIT_CP_WAIT_CLEANUP;
1782                 } else {
1783                         pp_buffer_stderr(&pp, opts, output_timeout);
1784                         pp_output(&pp);
1785                 }
1786                 code = pp_collect_finished(&pp, opts);
1787                 if (code) {
1788                         pp.shutdown = 1;
1789                         if (code < 0)
1790                                 kill_children(&pp, opts,-code);
1791                 }
1792         }
1793
1794         pp_cleanup(&pp, opts);
1795
1796         if (do_trace2)
1797                 trace2_region_leave(tr2_category, tr2_label, NULL);
1798 }
1799
1800 int run_auto_maintenance(int quiet)
1801 {
1802         int enabled;
1803         struct child_process maint = CHILD_PROCESS_INIT;
1804
1805         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1806             !enabled)
1807                 return 0;
1808
1809         maint.git_cmd = 1;
1810         maint.close_object_store = 1;
1811         strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
1812         strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
1813
1814         return run_command(&maint);
1815 }
1816
1817 void prepare_other_repo_env(struct strvec *env, const char *new_git_dir)
1818 {
1819         const char * const *var;
1820
1821         for (var = local_repo_env; *var; var++) {
1822                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1823                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1824                         strvec_push(env, *var);
1825         }
1826         strvec_pushf(env, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1827 }
1828
1829 enum start_bg_result start_bg_command(struct child_process *cmd,
1830                                       start_bg_wait_cb *wait_cb,
1831                                       void *cb_data,
1832                                       unsigned int timeout_sec)
1833 {
1834         enum start_bg_result sbgr = SBGR_ERROR;
1835         int ret;
1836         int wait_status;
1837         pid_t pid_seen;
1838         time_t time_limit;
1839
1840         /*
1841          * We do not allow clean-on-exit because the child process
1842          * should persist in the background and possibly/probably
1843          * after this process exits.  So we don't want to kill the
1844          * child during our atexit routine.
1845          */
1846         if (cmd->clean_on_exit)
1847                 BUG("start_bg_command() does not allow non-zero clean_on_exit");
1848
1849         if (!cmd->trace2_child_class)
1850                 cmd->trace2_child_class = "background";
1851
1852         ret = start_command(cmd);
1853         if (ret) {
1854                 /*
1855                  * We assume that if `start_command()` fails, we
1856                  * either get a complete `trace2_child_start() /
1857                  * trace2_child_exit()` pair or it fails before the
1858                  * `trace2_child_start()` is emitted, so we do not
1859                  * need to worry about it here.
1860                  *
1861                  * We also assume that `start_command()` does not add
1862                  * us to the cleanup list.  And that it calls
1863                  * `child_process_clear()`.
1864                  */
1865                 sbgr = SBGR_ERROR;
1866                 goto done;
1867         }
1868
1869         time(&time_limit);
1870         time_limit += timeout_sec;
1871
1872 wait:
1873         pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
1874
1875         if (!pid_seen) {
1876                 /*
1877                  * The child is currently running.  Ask the callback
1878                  * if the child is ready to do work or whether we
1879                  * should keep waiting for it to boot up.
1880                  */
1881                 ret = (*wait_cb)(cmd, cb_data);
1882                 if (!ret) {
1883                         /*
1884                          * The child is running and "ready".
1885                          */
1886                         trace2_child_ready(cmd, "ready");
1887                         sbgr = SBGR_READY;
1888                         goto done;
1889                 } else if (ret > 0) {
1890                         /*
1891                          * The callback said to give it more time to boot up
1892                          * (subject to our timeout limit).
1893                          */
1894                         time_t now;
1895
1896                         time(&now);
1897                         if (now < time_limit)
1898                                 goto wait;
1899
1900                         /*
1901                          * Our timeout has expired.  We don't try to
1902                          * kill the child, but rather let it continue
1903                          * (hopefully) trying to startup.
1904                          */
1905                         trace2_child_ready(cmd, "timeout");
1906                         sbgr = SBGR_TIMEOUT;
1907                         goto done;
1908                 } else {
1909                         /*
1910                          * The cb gave up on this child.  It is still running,
1911                          * but our cb got an error trying to probe it.
1912                          */
1913                         trace2_child_ready(cmd, "error");
1914                         sbgr = SBGR_CB_ERROR;
1915                         goto done;
1916                 }
1917         }
1918
1919         else if (pid_seen == cmd->pid) {
1920                 int child_code = -1;
1921
1922                 /*
1923                  * The child started, but exited or was terminated
1924                  * before becoming "ready".
1925                  *
1926                  * We try to match the behavior of `wait_or_whine()`
1927                  * WRT the handling of WIFSIGNALED() and WIFEXITED()
1928                  * and convert the child's status to a return code for
1929                  * tracing purposes and emit the `trace2_child_exit()`
1930                  * event.
1931                  *
1932                  * We do not want the wait_or_whine() error message
1933                  * because we will be called by client-side library
1934                  * routines.
1935                  */
1936                 if (WIFEXITED(wait_status))
1937                         child_code = WEXITSTATUS(wait_status);
1938                 else if (WIFSIGNALED(wait_status))
1939                         child_code = WTERMSIG(wait_status) + 128;
1940                 trace2_child_exit(cmd, child_code);
1941
1942                 sbgr = SBGR_DIED;
1943                 goto done;
1944         }
1945
1946         else if (pid_seen < 0 && errno == EINTR)
1947                 goto wait;
1948
1949         trace2_child_exit(cmd, -1);
1950         sbgr = SBGR_ERROR;
1951
1952 done:
1953         child_process_clear(cmd);
1954         invalidate_lstat_cache();
1955         return sbgr;
1956 }