run-command.c

   1 #define USE_THE_REPOSITORY_VARIABLE
   2
   3 #include "git-compat-util.h"
   4 #include "run-command.h"
   5 #include "environment.h"
   6 #include "exec-cmd.h"
   7 #include "gettext.h"
   8 #include "sigchain.h"
   9 #include "strvec.h"
  10 #include "symlinks.h"
  11 #include "thread-utils.h"
  12 #include "strbuf.h"
  13 #include "string-list.h"
  14 #include "trace.h"
  15 #include "trace2.h"
  16 #include "quote.h"
  17 #include "config.h"
  18 #include "packfile.h"
  19 #include "compat/nonblock.h"
  20
  21 void child_process_init(struct child_process *child)
  22 {
  23         struct child_process blank = CHILD_PROCESS_INIT;
  24         memcpy(child, &blank, sizeof(*child));
  25 }
  26
  27 void child_process_clear(struct child_process *child)
  28 {
  29         strvec_clear(&child->args);
  30         strvec_clear(&child->env);
  31 }
  32
  33 struct child_to_clean {
  34         pid_t pid;
  35         struct child_process *process;
  36         struct child_to_clean *next;
  37 };
  38 static struct child_to_clean *children_to_clean;
  39 static int installed_child_cleanup_handler;
  40
  41 static void cleanup_children(int sig, int in_signal)
  42 {
  43         struct child_to_clean *children_to_wait_for = NULL;
  44
  45         while (children_to_clean) {
  46                 struct child_to_clean *p = children_to_clean;
  47                 children_to_clean = p->next;
  48
  49                 if (p->process && !in_signal) {
  50                         struct child_process *process = p->process;
  51                         if (process->clean_on_exit_handler) {
  52                                 trace_printf(
  53                                         "trace: run_command: running exit handler for pid %"
  54                                         PRIuMAX, (uintmax_t)p->pid
  55                                 );
  56                                 process->clean_on_exit_handler(process);
  57                         }
  58                 }
  59
  60                 kill(p->pid, sig);
  61
  62                 if (p->process && p->process->wait_after_clean) {
  63                         p->next = children_to_wait_for;
  64                         children_to_wait_for = p;
  65                 } else {
  66                         if (!in_signal)
  67                                 free(p);
  68                 }
  69         }
  70
  71         while (children_to_wait_for) {
  72                 struct child_to_clean *p = children_to_wait_for;
  73                 children_to_wait_for = p->next;
  74
  75                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  76                         ; /* spin waiting for process exit or error */
  77
  78                 if (!in_signal)
  79                         free(p);
  80         }
  81 }
  82
  83 static void cleanup_children_on_signal(int sig)
  84 {
  85         cleanup_children(sig, 1);
  86         sigchain_pop(sig);
  87         raise(sig);
  88 }
  89
  90 static void cleanup_children_on_exit(void)
  91 {
  92         cleanup_children(SIGTERM, 0);
  93 }
  94
  95 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  96 {
  97         struct child_to_clean *p = xmalloc(sizeof(*p));
  98         p->pid = pid;
  99         p->process = process;
 100         p->next = children_to_clean;
 101         children_to_clean = p;
 102
 103         if (!installed_child_cleanup_handler) {
 104                 atexit(cleanup_children_on_exit);
 105                 sigchain_push_common(cleanup_children_on_signal);
 106                 installed_child_cleanup_handler = 1;
 107         }
 108 }
 109
 110 static void clear_child_for_cleanup(pid_t pid)
 111 {
 112         struct child_to_clean **pp;
 113
 114         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 115                 struct child_to_clean *clean_me = *pp;
 116
 117                 if (clean_me->pid == pid) {
 118                         *pp = clean_me->next;
 119                         free(clean_me);
 120                         return;
 121                 }
 122         }
 123 }
 124
 125 static inline void close_pair(int fd[2])
 126 {
 127         close(fd[0]);
 128         close(fd[1]);
 129 }
 130
 131 int is_executable(const char *name)
 132 {
 133         struct stat st;
 134
 135         if (stat(name, &st) || /* stat, not lstat */
 136             !S_ISREG(st.st_mode))
 137                 return 0;
 138
 139 #if defined(GIT_WINDOWS_NATIVE)
 140         /*
 141          * On Windows there is no executable bit. The file extension
 142          * indicates whether it can be run as an executable, and Git
 143          * has special-handling to detect scripts and launch them
 144          * through the indicated script interpreter. We test for the
 145          * file extension first because virus scanners may make
 146          * it quite expensive to open many files.
 147          */
 148         if (ends_with(name, ".exe"))
 149                 return S_IXUSR;
 150
 151 {
 152         /*
 153          * Now that we know it does not have an executable extension,
 154          * peek into the file instead.
 155          */
 156         char buf[3] = { 0 };
 157         int n;
 158         int fd = open(name, O_RDONLY);
 159         st.st_mode &= ~S_IXUSR;
 160         if (fd >= 0) {
 161                 n = read(fd, buf, 2);
 162                 if (n == 2)
 163                         /* look for a she-bang */
 164                         if (!strcmp(buf, "#!"))
 165                                 st.st_mode |= S_IXUSR;
 166                 close(fd);
 167         }
 168 }
 169 #endif
 170         return st.st_mode & S_IXUSR;
 171 }
 172
 173 #ifndef locate_in_PATH
 174 /*
 175  * Search $PATH for a command.  This emulates the path search that
 176  * execvp would perform, without actually executing the command so it
 177  * can be used before fork() to prepare to run a command using
 178  * execve() or after execvp() to diagnose why it failed.
 179  *
 180  * The caller should ensure that file contains no directory
 181  * separators.
 182  *
 183  * Returns the path to the command, as found in $PATH or NULL if the
 184  * command could not be found.  The caller inherits ownership of the memory
 185  * used to store the resultant path.
 186  *
 187  * This should not be used on Windows, where the $PATH search rules
 188  * are more complicated (e.g., a search for "foo" should find
 189  * "foo.exe").
 190  */
 191 static char *locate_in_PATH(const char *file)
 192 {
 193         const char *p = getenv("PATH");
 194         struct strbuf buf = STRBUF_INIT;
 195
 196         if (!p || !*p)
 197                 return NULL;
 198
 199         while (1) {
 200                 const char *end = strchrnul(p, ':');
 201
 202                 strbuf_reset(&buf);
 203
 204                 /* POSIX specifies an empty entry as the current directory. */
 205                 if (end != p) {
 206                         strbuf_add(&buf, p, end - p);
 207                         strbuf_addch(&buf, '/');
 208                 }
 209                 strbuf_addstr(&buf, file);
 210
 211                 if (is_executable(buf.buf))
 212                         return strbuf_detach(&buf, NULL);
 213
 214                 if (!*end)
 215                         break;
 216                 p = end + 1;
 217         }
 218
 219         strbuf_release(&buf);
 220         return NULL;
 221 }
 222 #endif
 223
 224 int exists_in_PATH(const char *command)
 225 {
 226         char *r = locate_in_PATH(command);
 227         int found = r != NULL;
 228         free(r);
 229         return found;
 230 }
 231
 232 int sane_execvp(const char *file, char * const argv[])
 233 {
 234 #ifndef GIT_WINDOWS_NATIVE
 235         /*
 236          * execvp() doesn't return, so we all we can do is tell trace2
 237          * what we are about to do and let it leave a hint in the log
 238          * (unless of course the execvp() fails).
 239          *
 240          * we skip this for Windows because the compat layer already
 241          * has to emulate the execvp() call anyway.
 242          */
 243         int exec_id = trace2_exec(file, (const char **)argv);
 244 #endif
 245
 246         if (!execvp(file, argv))
 247                 return 0; /* cannot happen ;-) */
 248
 249 #ifndef GIT_WINDOWS_NATIVE
 250         {
 251                 int ec = errno;
 252                 trace2_exec_result(exec_id, ec);
 253                 errno = ec;
 254         }
 255 #endif
 256
 257         /*
 258          * When a command can't be found because one of the directories
 259          * listed in $PATH is unsearchable, execvp reports EACCES, but
 260          * careful usability testing (read: analysis of occasional bug
 261          * reports) reveals that "No such file or directory" is more
 262          * intuitive.
 263          *
 264          * We avoid commands with "/", because execvp will not do $PATH
 265          * lookups in that case.
 266          *
 267          * The reassignment of EACCES to errno looks like a no-op below,
 268          * but we need to protect against exists_in_PATH overwriting errno.
 269          */
 270         if (errno == EACCES && !strchr(file, '/'))
 271                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 272         else if (errno == ENOTDIR && !strchr(file, '/'))
 273                 errno = ENOENT;
 274         return -1;
 275 }
 276
 277 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 278 {
 279         if (!argv[0])
 280                 BUG("shell command is empty");
 281
 282         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 283 #ifndef GIT_WINDOWS_NATIVE
 284                 strvec_push(out, SHELL_PATH);
 285 #else
 286                 strvec_push(out, "sh");
 287 #endif
 288                 strvec_push(out, "-c");
 289
 290                 /*
 291                  * If we have no extra arguments, we do not even need to
 292                  * bother with the "$@" magic.
 293                  */
 294                 if (!argv[1])
 295                         strvec_push(out, argv[0]);
 296                 else
 297                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 298         }
 299
 300         strvec_pushv(out, argv);
 301         return out->v;
 302 }
 303
 304 #ifndef GIT_WINDOWS_NATIVE
 305 static int child_notifier = -1;
 306
 307 enum child_errcode {
 308         CHILD_ERR_CHDIR,
 309         CHILD_ERR_DUP2,
 310         CHILD_ERR_CLOSE,
 311         CHILD_ERR_SIGPROCMASK,
 312         CHILD_ERR_SILENT,
 313         CHILD_ERR_ERRNO
 314 };
 315
 316 struct child_err {
 317         enum child_errcode err;
 318         int syserr; /* errno */
 319 };
 320
 321 static void child_die(enum child_errcode err)
 322 {
 323         struct child_err buf;
 324
 325         buf.err = err;
 326         buf.syserr = errno;
 327
 328         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 329         xwrite(child_notifier, &buf, sizeof(buf));
 330         _exit(1);
 331 }
 332
 333 static void child_dup2(int fd, int to)
 334 {
 335         if (dup2(fd, to) < 0)
 336                 child_die(CHILD_ERR_DUP2);
 337 }
 338
 339 static void child_close(int fd)
 340 {
 341         if (close(fd))
 342                 child_die(CHILD_ERR_CLOSE);
 343 }
 344
 345 static void child_close_pair(int fd[2])
 346 {
 347         child_close(fd[0]);
 348         child_close(fd[1]);
 349 }
 350
 351 static void child_error_fn(const char *err UNUSED, va_list params UNUSED)
 352 {
 353         const char msg[] = "error() should not be called in child\n";
 354         xwrite(2, msg, sizeof(msg) - 1);
 355 }
 356
 357 static void child_warn_fn(const char *err UNUSED, va_list params UNUSED)
 358 {
 359         const char msg[] = "warn() should not be called in child\n";
 360         xwrite(2, msg, sizeof(msg) - 1);
 361 }
 362
 363 static void NORETURN child_die_fn(const char *err UNUSED, va_list params UNUSED)
 364 {
 365         const char msg[] = "die() should not be called in child\n";
 366         xwrite(2, msg, sizeof(msg) - 1);
 367         _exit(2);
 368 }
 369
 370 /* this runs in the parent process */
 371 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 372 {
 373         static void (*old_errfn)(const char *err, va_list params);
 374         report_fn die_message_routine = get_die_message_routine();
 375
 376         old_errfn = get_error_routine();
 377         set_error_routine(die_message_routine);
 378         errno = cerr->syserr;
 379
 380         switch (cerr->err) {
 381         case CHILD_ERR_CHDIR:
 382                 error_errno("exec '%s': cd to '%s' failed",
 383                             cmd->args.v[0], cmd->dir);
 384                 break;
 385         case CHILD_ERR_DUP2:
 386                 error_errno("dup2() in child failed");
 387                 break;
 388         case CHILD_ERR_CLOSE:
 389                 error_errno("close() in child failed");
 390                 break;
 391         case CHILD_ERR_SIGPROCMASK:
 392                 error_errno("sigprocmask failed restoring signals");
 393                 break;
 394         case CHILD_ERR_SILENT:
 395                 break;
 396         case CHILD_ERR_ERRNO:
 397                 error_errno("cannot exec '%s'", cmd->args.v[0]);
 398                 break;
 399         }
 400         set_error_routine(old_errfn);
 401 }
 402
 403 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 404 {
 405         if (!cmd->args.v[0])
 406                 BUG("command is empty");
 407
 408         /*
 409          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 410          * attempt to interpret the command with 'sh'.
 411          */
 412         strvec_push(out, SHELL_PATH);
 413
 414         if (cmd->git_cmd) {
 415                 prepare_git_cmd(out, cmd->args.v);
 416         } else if (cmd->use_shell) {
 417                 prepare_shell_cmd(out, cmd->args.v);
 418         } else {
 419                 strvec_pushv(out, cmd->args.v);
 420         }
 421
 422         /*
 423          * If there are no dir separator characters in the command then perform
 424          * a path lookup and use the resolved path as the command to exec. If
 425          * there are dir separator characters, we have exec attempt to invoke
 426          * the command directly.
 427          */
 428         if (!has_dir_sep(out->v[1])) {
 429                 char *program = locate_in_PATH(out->v[1]);
 430                 if (program) {
 431                         free((char *)out->v[1]);
 432                         out->v[1] = program;
 433                 } else {
 434                         strvec_clear(out);
 435                         errno = ENOENT;
 436                         return -1;
 437                 }
 438         }
 439
 440         return 0;
 441 }
 442
 443 static char **prep_childenv(const char *const *deltaenv)
 444 {
 445         extern char **environ;
 446         char **childenv;
 447         struct string_list env = STRING_LIST_INIT_DUP;
 448         struct strbuf key = STRBUF_INIT;
 449         const char *const *p;
 450         int i;
 451
 452         /* Construct a sorted string list consisting of the current environ */
 453         for (p = (const char *const *) environ; p && *p; p++) {
 454                 const char *equals = strchr(*p, '=');
 455
 456                 if (equals) {
 457                         strbuf_reset(&key);
 458                         strbuf_add(&key, *p, equals - *p);
 459                         string_list_append(&env, key.buf)->util = (void *) *p;
 460                 } else {
 461                         string_list_append(&env, *p)->util = (void *) *p;
 462                 }
 463         }
 464         string_list_sort(&env);
 465
 466         /* Merge in 'deltaenv' with the current environ */
 467         for (p = deltaenv; p && *p; p++) {
 468                 const char *equals = strchr(*p, '=');
 469
 470                 if (equals) {
 471                         /* ('key=value'), insert or replace entry */
 472                         strbuf_reset(&key);
 473                         strbuf_add(&key, *p, equals - *p);
 474                         string_list_insert(&env, key.buf)->util = (void *) *p;
 475                 } else {
 476                         /* otherwise ('key') remove existing entry */
 477                         string_list_remove(&env, *p, 0);
 478                 }
 479         }
 480
 481         /* Create an array of 'char *' to be used as the childenv */
 482         ALLOC_ARRAY(childenv, env.nr + 1);
 483         for (i = 0; i < env.nr; i++)
 484                 childenv[i] = env.items[i].util;
 485         childenv[env.nr] = NULL;
 486
 487         string_list_clear(&env, 0);
 488         strbuf_release(&key);
 489         return childenv;
 490 }
 491
 492 struct atfork_state {
 493 #ifndef NO_PTHREADS
 494         int cs;
 495 #endif
 496         sigset_t old;
 497 };
 498
 499 #define CHECK_BUG(err, msg) \
 500         do { \
 501                 int e = (err); \
 502                 if (e) \
 503                         BUG("%s: %s", msg, strerror(e)); \
 504         } while(0)
 505
 506 static void atfork_prepare(struct atfork_state *as)
 507 {
 508         sigset_t all;
 509
 510         if (sigfillset(&all))
 511                 die_errno("sigfillset");
 512 #ifdef NO_PTHREADS
 513         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 514                 die_errno("sigprocmask");
 515 #else
 516         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 517                 "blocking all signals");
 518         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 519                 "disabling cancellation");
 520 #endif
 521 }
 522
 523 static void atfork_parent(struct atfork_state *as)
 524 {
 525 #ifdef NO_PTHREADS
 526         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 527                 die_errno("sigprocmask");
 528 #else
 529         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 530                 "re-enabling cancellation");
 531         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 532                 "restoring signal mask");
 533 #endif
 534 }
 535 #endif /* GIT_WINDOWS_NATIVE */
 536
 537 static inline void set_cloexec(int fd)
 538 {
 539         int flags = fcntl(fd, F_GETFD);
 540         if (flags >= 0)
 541                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 542 }
 543
 544 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 545 {
 546         int status, code = -1;
 547         pid_t waiting;
 548         int failed_errno = 0;
 549
 550         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 551                 ;       /* nothing */
 552
 553         if (waiting < 0) {
 554                 failed_errno = errno;
 555                 if (!in_signal)
 556                         error_errno("waitpid for %s failed", argv0);
 557         } else if (waiting != pid) {
 558                 if (!in_signal)
 559                         error("waitpid is confused (%s)", argv0);
 560         } else if (WIFSIGNALED(status)) {
 561                 code = WTERMSIG(status);
 562                 if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 563                         error("%s died of signal %d", argv0, code);
 564                 /*
 565                  * This return value is chosen so that code & 0xff
 566                  * mimics the exit code that a POSIX shell would report for
 567                  * a program that died from this signal.
 568                  */
 569                 code += 128;
 570         } else if (WIFEXITED(status)) {
 571                 code = WEXITSTATUS(status);
 572         } else {
 573                 if (!in_signal)
 574                         error("waitpid is confused (%s)", argv0);
 575         }
 576
 577         if (!in_signal)
 578                 clear_child_for_cleanup(pid);
 579
 580         errno = failed_errno;
 581         return code;
 582 }
 583
 584 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 585 {
 586         struct string_list envs = STRING_LIST_INIT_DUP;
 587         const char *const *e;
 588         int i;
 589         int printed_unset = 0;
 590
 591         /* Last one wins, see run-command.c:prep_childenv() for context */
 592         for (e = deltaenv; e && *e; e++) {
 593                 struct strbuf key = STRBUF_INIT;
 594                 char *equals = strchr(*e, '=');
 595
 596                 if (equals) {
 597                         strbuf_add(&key, *e, equals - *e);
 598                         string_list_insert(&envs, key.buf)->util = equals + 1;
 599                 } else {
 600                         string_list_insert(&envs, *e)->util = NULL;
 601                 }
 602                 strbuf_release(&key);
 603         }
 604
 605         /* "unset X Y...;" */
 606         for (i = 0; i < envs.nr; i++) {
 607                 const char *var = envs.items[i].string;
 608                 const char *val = envs.items[i].util;
 609
 610                 if (val || !getenv(var))
 611                         continue;
 612
 613                 if (!printed_unset) {
 614                         strbuf_addstr(dst, " unset");
 615                         printed_unset = 1;
 616                 }
 617                 strbuf_addf(dst, " %s", var);
 618         }
 619         if (printed_unset)
 620                 strbuf_addch(dst, ';');
 621
 622         /* ... followed by "A=B C=D ..." */
 623         for (i = 0; i < envs.nr; i++) {
 624                 const char *var = envs.items[i].string;
 625                 const char *val = envs.items[i].util;
 626                 const char *oldval;
 627
 628                 if (!val)
 629                         continue;
 630
 631                 oldval = getenv(var);
 632                 if (oldval && !strcmp(val, oldval))
 633                         continue;
 634
 635                 strbuf_addf(dst, " %s=", var);
 636                 sq_quote_buf_pretty(dst, val);
 637         }
 638         string_list_clear(&envs, 0);
 639 }
 640
 641 static void trace_run_command(const struct child_process *cp)
 642 {
 643         struct strbuf buf = STRBUF_INIT;
 644
 645         if (!trace_want(&trace_default_key))
 646                 return;
 647
 648         strbuf_addstr(&buf, "trace: run_command:");
 649         if (cp->dir) {
 650                 strbuf_addstr(&buf, " cd ");
 651                 sq_quote_buf_pretty(&buf, cp->dir);
 652                 strbuf_addch(&buf, ';');
 653         }
 654         trace_add_env(&buf, cp->env.v);
 655         if (cp->git_cmd)
 656                 strbuf_addstr(&buf, " git");
 657         sq_quote_argv_pretty(&buf, cp->args.v);
 658
 659         trace_printf("%s", buf.buf);
 660         strbuf_release(&buf);
 661 }
 662
 663 int start_command(struct child_process *cmd)
 664 {
 665         int need_in, need_out, need_err;
 666         int fdin[2], fdout[2], fderr[2];
 667         int failed_errno;
 668         const char *str;
 669
 670         /*
 671          * In case of errors we must keep the promise to close FDs
 672          * that have been passed in via ->in and ->out.
 673          */
 674
 675         need_in = !cmd->no_stdin && cmd->in < 0;
 676         if (need_in) {
 677                 if (pipe(fdin) < 0) {
 678                         failed_errno = errno;
 679                         if (cmd->out > 0)
 680                                 close(cmd->out);
 681                         str = "standard input";
 682                         goto fail_pipe;
 683                 }
 684                 cmd->in = fdin[1];
 685         }
 686
 687         need_out = !cmd->no_stdout
 688                 && !cmd->stdout_to_stderr
 689                 && cmd->out < 0;
 690         if (need_out) {
 691                 if (pipe(fdout) < 0) {
 692                         failed_errno = errno;
 693                         if (need_in)
 694                                 close_pair(fdin);
 695                         else if (cmd->in)
 696                                 close(cmd->in);
 697                         str = "standard output";
 698                         goto fail_pipe;
 699                 }
 700                 cmd->out = fdout[0];
 701         }
 702
 703         need_err = !cmd->no_stderr && cmd->err < 0;
 704         if (need_err) {
 705                 if (pipe(fderr) < 0) {
 706                         failed_errno = errno;
 707                         if (need_in)
 708                                 close_pair(fdin);
 709                         else if (cmd->in)
 710                                 close(cmd->in);
 711                         if (need_out)
 712                                 close_pair(fdout);
 713                         else if (cmd->out)
 714                                 close(cmd->out);
 715                         str = "standard error";
 716 fail_pipe:
 717                         error("cannot create %s pipe for %s: %s",
 718                                 str, cmd->args.v[0], strerror(failed_errno));
 719                         child_process_clear(cmd);
 720                         errno = failed_errno;
 721                         return -1;
 722                 }
 723                 cmd->err = fderr[0];
 724         }
 725
 726         trace2_child_start(cmd);
 727         trace_run_command(cmd);
 728
 729         fflush(NULL);
 730
 731         if (cmd->close_object_store)
 732                 close_object_store(the_repository->objects);
 733
 734 #ifndef GIT_WINDOWS_NATIVE
 735 {
 736         int notify_pipe[2];
 737         int null_fd = -1;
 738         char **childenv;
 739         struct strvec argv = STRVEC_INIT;
 740         struct child_err cerr;
 741         struct atfork_state as;
 742
 743         if (prepare_cmd(&argv, cmd) < 0) {
 744                 failed_errno = errno;
 745                 cmd->pid = -1;
 746                 if (!cmd->silent_exec_failure)
 747                         error_errno("cannot run %s", cmd->args.v[0]);
 748                 goto end_of_spawn;
 749         }
 750
 751         trace_argv_printf(&argv.v[1], "trace: start_command:");
 752
 753         if (pipe(notify_pipe))
 754                 notify_pipe[0] = notify_pipe[1] = -1;
 755
 756         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 757                 null_fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
 758                 set_cloexec(null_fd);
 759         }
 760
 761         childenv = prep_childenv(cmd->env.v);
 762         atfork_prepare(&as);
 763
 764         /*
 765          * NOTE: In order to prevent deadlocking when using threads special
 766          * care should be taken with the function calls made in between the
 767          * fork() and exec() calls.  No calls should be made to functions which
 768          * require acquiring a lock (e.g. malloc) as the lock could have been
 769          * held by another thread at the time of forking, causing the lock to
 770          * never be released in the child process.  This means only
 771          * Async-Signal-Safe functions are permitted in the child.
 772          */
 773         cmd->pid = fork();
 774         failed_errno = errno;
 775         if (!cmd->pid) {
 776                 int sig;
 777                 /*
 778                  * Ensure the default die/error/warn routines do not get
 779                  * called, they can take stdio locks and malloc.
 780                  */
 781                 set_die_routine(child_die_fn);
 782                 set_error_routine(child_error_fn);
 783                 set_warn_routine(child_warn_fn);
 784
 785                 close(notify_pipe[0]);
 786                 set_cloexec(notify_pipe[1]);
 787                 child_notifier = notify_pipe[1];
 788
 789                 if (cmd->no_stdin)
 790                         child_dup2(null_fd, 0);
 791                 else if (need_in) {
 792                         child_dup2(fdin[0], 0);
 793                         child_close_pair(fdin);
 794                 } else if (cmd->in) {
 795                         child_dup2(cmd->in, 0);
 796                         child_close(cmd->in);
 797                 }
 798
 799                 if (cmd->no_stderr)
 800                         child_dup2(null_fd, 2);
 801                 else if (need_err) {
 802                         child_dup2(fderr[1], 2);
 803                         child_close_pair(fderr);
 804                 } else if (cmd->err > 1) {
 805                         child_dup2(cmd->err, 2);
 806                         child_close(cmd->err);
 807                 }
 808
 809                 if (cmd->no_stdout)
 810                         child_dup2(null_fd, 1);
 811                 else if (cmd->stdout_to_stderr)
 812                         child_dup2(2, 1);
 813                 else if (need_out) {
 814                         child_dup2(fdout[1], 1);
 815                         child_close_pair(fdout);
 816                 } else if (cmd->out > 1) {
 817                         child_dup2(cmd->out, 1);
 818                         child_close(cmd->out);
 819                 }
 820
 821                 if (cmd->dir && chdir(cmd->dir))
 822                         child_die(CHILD_ERR_CHDIR);
 823
 824                 /*
 825                  * restore default signal handlers here, in case
 826                  * we catch a signal right before execve below
 827                  */
 828                 for (sig = 1; sig < NSIG; sig++) {
 829                         /* ignored signals get reset to SIG_DFL on execve */
 830                         if (signal(sig, SIG_DFL) == SIG_IGN)
 831                                 signal(sig, SIG_IGN);
 832                 }
 833
 834                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 835                         child_die(CHILD_ERR_SIGPROCMASK);
 836
 837                 /*
 838                  * Attempt to exec using the command and arguments starting at
 839                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 840                  * be used in the event exec failed with ENOEXEC at which point
 841                  * we will try to interpret the command using 'sh'.
 842                  */
 843                 execve(argv.v[1], (char *const *) argv.v + 1,
 844                        (char *const *) childenv);
 845                 if (errno == ENOEXEC)
 846                         execve(argv.v[0], (char *const *) argv.v,
 847                                (char *const *) childenv);
 848
 849                 if (cmd->silent_exec_failure && errno == ENOENT)
 850                         child_die(CHILD_ERR_SILENT);
 851                 child_die(CHILD_ERR_ERRNO);
 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         trace_argv_printf(cmd->args.v, "trace: start_command:");
 921         cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v,
 922                                   (char**) cmd->env.v,
 923                                   cmd->dir, fhin, fhout, fherr);
 924         failed_errno = errno;
 925         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 926                 error_errno("cannot spawn %s", cmd->args.v[0]);
 927         if (cmd->clean_on_exit && cmd->pid >= 0)
 928                 mark_child_for_cleanup(cmd->pid, cmd);
 929
 930         strvec_clear(&nargv);
 931         cmd->args.v = sargv;
 932         if (fhin != 0)
 933                 close(fhin);
 934         if (fhout != 1)
 935                 close(fhout);
 936         if (fherr != 2)
 937                 close(fherr);
 938 }
 939 #endif
 940
 941         if (cmd->pid < 0) {
 942                 trace2_child_exit(cmd, -1);
 943
 944                 if (need_in)
 945                         close_pair(fdin);
 946                 else if (cmd->in)
 947                         close(cmd->in);
 948                 if (need_out)
 949                         close_pair(fdout);
 950                 else if (cmd->out)
 951                         close(cmd->out);
 952                 if (need_err)
 953                         close_pair(fderr);
 954                 else if (cmd->err)
 955                         close(cmd->err);
 956                 child_process_clear(cmd);
 957                 errno = failed_errno;
 958                 return -1;
 959         }
 960
 961         if (need_in)
 962                 close(fdin[0]);
 963         else if (cmd->in)
 964                 close(cmd->in);
 965
 966         if (need_out)
 967                 close(fdout[1]);
 968         else if (cmd->out)
 969                 close(cmd->out);
 970
 971         if (need_err)
 972                 close(fderr[1]);
 973         else if (cmd->err)
 974                 close(cmd->err);
 975
 976         return 0;
 977 }
 978
 979 int finish_command(struct child_process *cmd)
 980 {
 981         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 982         trace2_child_exit(cmd, ret);
 983         child_process_clear(cmd);
 984         invalidate_lstat_cache();
 985         return ret;
 986 }
 987
 988 int finish_command_in_signal(struct child_process *cmd)
 989 {
 990         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
 991         if (ret != -1)
 992                 trace2_child_exit(cmd, ret);
 993         return ret;
 994 }
 995
 996
 997 int run_command(struct child_process *cmd)
 998 {
 999         int code;
1000
1001         if (cmd->out < 0 || cmd->err < 0)
1002                 BUG("run_command with a pipe can cause deadlock");
1003
1004         code = start_command(cmd);
1005         if (code)
1006                 return code;
1007         return finish_command(cmd);
1008 }
1009
1010 #ifndef NO_PTHREADS
1011 static pthread_t main_thread;
1012 static int main_thread_set;
1013 static pthread_key_t async_key;
1014 static pthread_key_t async_die_counter;
1015
1016 static void *run_thread(void *data)
1017 {
1018         struct async *async = data;
1019         intptr_t ret;
1020
1021         if (async->isolate_sigpipe) {
1022                 sigset_t mask;
1023                 sigemptyset(&mask);
1024                 sigaddset(&mask, SIGPIPE);
1025                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL)) {
1026                         ret = error("unable to block SIGPIPE in async thread");
1027                         return (void *)ret;
1028                 }
1029         }
1030
1031         pthread_setspecific(async_key, async);
1032         ret = async->proc(async->proc_in, async->proc_out, async->data);
1033         return (void *)ret;
1034 }
1035
1036 static NORETURN void die_async(const char *err, va_list params)
1037 {
1038         report_fn die_message_fn = get_die_message_routine();
1039
1040         die_message_fn(err, params);
1041
1042         if (in_async()) {
1043                 struct async *async = pthread_getspecific(async_key);
1044                 if (async->proc_in >= 0)
1045                         close(async->proc_in);
1046                 if (async->proc_out >= 0)
1047                         close(async->proc_out);
1048                 pthread_exit((void *)128);
1049         }
1050
1051         exit(128);
1052 }
1053
1054 static int async_die_is_recursing(void)
1055 {
1056         void *ret = pthread_getspecific(async_die_counter);
1057         pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
1058         return ret != NULL;
1059 }
1060
1061 int in_async(void)
1062 {
1063         if (!main_thread_set)
1064                 return 0; /* no asyncs started yet */
1065         return !pthread_equal(main_thread, pthread_self());
1066 }
1067
1068 static void NORETURN async_exit(int code)
1069 {
1070         pthread_exit((void *)(intptr_t)code);
1071 }
1072
1073 #else
1074
1075 static struct {
1076         void (**handlers)(void);
1077         size_t nr;
1078         size_t alloc;
1079 } git_atexit_hdlrs;
1080
1081 static int git_atexit_installed;
1082
1083 static void git_atexit_dispatch(void)
1084 {
1085         size_t i;
1086
1087         for (i=git_atexit_hdlrs.nr ; i ; i--)
1088                 git_atexit_hdlrs.handlers[i-1]();
1089 }
1090
1091 static void git_atexit_clear(void)
1092 {
1093         free(git_atexit_hdlrs.handlers);
1094         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1095         git_atexit_installed = 0;
1096 }
1097
1098 #undef atexit
1099 int git_atexit(void (*handler)(void))
1100 {
1101         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1102         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1103         if (!git_atexit_installed) {
1104                 if (atexit(&git_atexit_dispatch))
1105                         return -1;
1106                 git_atexit_installed = 1;
1107         }
1108         return 0;
1109 }
1110 #define atexit git_atexit
1111
1112 static int process_is_async;
1113 int in_async(void)
1114 {
1115         return process_is_async;
1116 }
1117
1118 static void NORETURN async_exit(int code)
1119 {
1120         exit(code);
1121 }
1122
1123 #endif
1124
1125 void check_pipe(int err)
1126 {
1127         if (err == EPIPE) {
1128                 if (in_async())
1129                         async_exit(141);
1130
1131                 signal(SIGPIPE, SIG_DFL);
1132                 raise(SIGPIPE);
1133                 /* Should never happen, but just in case... */
1134                 exit(141);
1135         }
1136 }
1137
1138 int start_async(struct async *async)
1139 {
1140         int need_in, need_out;
1141         int fdin[2], fdout[2];
1142         int proc_in, proc_out;
1143
1144         need_in = async->in < 0;
1145         if (need_in) {
1146                 if (pipe(fdin) < 0) {
1147                         if (async->out > 0)
1148                                 close(async->out);
1149                         return error_errno("cannot create pipe");
1150                 }
1151                 async->in = fdin[1];
1152         }
1153
1154         need_out = async->out < 0;
1155         if (need_out) {
1156                 if (pipe(fdout) < 0) {
1157                         if (need_in)
1158                                 close_pair(fdin);
1159                         else if (async->in)
1160                                 close(async->in);
1161                         return error_errno("cannot create pipe");
1162                 }
1163                 async->out = fdout[0];
1164         }
1165
1166         if (need_in)
1167                 proc_in = fdin[0];
1168         else if (async->in)
1169                 proc_in = async->in;
1170         else
1171                 proc_in = -1;
1172
1173         if (need_out)
1174                 proc_out = fdout[1];
1175         else if (async->out)
1176                 proc_out = async->out;
1177         else
1178                 proc_out = -1;
1179
1180 #ifdef NO_PTHREADS
1181         /* Flush stdio before fork() to avoid cloning buffers */
1182         fflush(NULL);
1183
1184         async->pid = fork();
1185         if (async->pid < 0) {
1186                 error_errno("fork (async) failed");
1187                 goto error;
1188         }
1189         if (!async->pid) {
1190                 if (need_in)
1191                         close(fdin[1]);
1192                 if (need_out)
1193                         close(fdout[0]);
1194                 git_atexit_clear();
1195                 process_is_async = 1;
1196                 exit(!!async->proc(proc_in, proc_out, async->data));
1197         }
1198
1199         mark_child_for_cleanup(async->pid, NULL);
1200
1201         if (need_in)
1202                 close(fdin[0]);
1203         else if (async->in)
1204                 close(async->in);
1205
1206         if (need_out)
1207                 close(fdout[1]);
1208         else if (async->out)
1209                 close(async->out);
1210 #else
1211         if (!main_thread_set) {
1212                 /*
1213                  * We assume that the first time that start_async is called
1214                  * it is from the main thread.
1215                  */
1216                 main_thread_set = 1;
1217                 main_thread = pthread_self();
1218                 pthread_key_create(&async_key, NULL);
1219                 pthread_key_create(&async_die_counter, NULL);
1220                 set_die_routine(die_async);
1221                 set_die_is_recursing_routine(async_die_is_recursing);
1222         }
1223
1224         if (proc_in >= 0)
1225                 set_cloexec(proc_in);
1226         if (proc_out >= 0)
1227                 set_cloexec(proc_out);
1228         async->proc_in = proc_in;
1229         async->proc_out = proc_out;
1230         {
1231                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1232                 if (err) {
1233                         error(_("cannot create async thread: %s"), strerror(err));
1234                         goto error;
1235                 }
1236         }
1237 #endif
1238         return 0;
1239
1240 error:
1241         if (need_in)
1242                 close_pair(fdin);
1243         else if (async->in)
1244                 close(async->in);
1245
1246         if (need_out)
1247                 close_pair(fdout);
1248         else if (async->out)
1249                 close(async->out);
1250         return -1;
1251 }
1252
1253 int finish_async(struct async *async)
1254 {
1255 #ifdef NO_PTHREADS
1256         int ret = wait_or_whine(async->pid, "child process", 0);
1257
1258         invalidate_lstat_cache();
1259
1260         return ret;
1261 #else
1262         void *ret = (void *)(intptr_t)(-1);
1263
1264         if (pthread_join(async->tid, &ret))
1265                 error("pthread_join failed");
1266         invalidate_lstat_cache();
1267         return (int)(intptr_t)ret;
1268
1269 #endif
1270 }
1271
1272 int async_with_fork(void)
1273 {
1274 #ifdef NO_PTHREADS
1275         return 1;
1276 #else
1277         return 0;
1278 #endif
1279 }
1280
1281 struct io_pump {
1282         /* initialized by caller */
1283         int fd;
1284         int type; /* POLLOUT or POLLIN */
1285         union {
1286                 struct {
1287                         const char *buf;
1288                         size_t len;
1289                 } out;
1290                 struct {
1291                         struct strbuf *buf;
1292                         size_t hint;
1293                 } in;
1294         } u;
1295
1296         /* returned by pump_io */
1297         int error; /* 0 for success, otherwise errno */
1298
1299         /* internal use */
1300         struct pollfd *pfd;
1301 };
1302
1303 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1304 {
1305         int pollsize = 0;
1306         int i;
1307
1308         for (i = 0; i < nr; i++) {
1309                 struct io_pump *io = &slots[i];
1310                 if (io->fd < 0)
1311                         continue;
1312                 pfd[pollsize].fd = io->fd;
1313                 pfd[pollsize].events = io->type;
1314                 io->pfd = &pfd[pollsize++];
1315         }
1316
1317         if (!pollsize)
1318                 return 0;
1319
1320         if (poll(pfd, pollsize, -1) < 0) {
1321                 if (errno == EINTR)
1322                         return 1;
1323                 die_errno("poll failed");
1324         }
1325
1326         for (i = 0; i < nr; i++) {
1327                 struct io_pump *io = &slots[i];
1328
1329                 if (io->fd < 0)
1330                         continue;
1331
1332                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1333                         continue;
1334
1335                 if (io->type == POLLOUT) {
1336                         ssize_t len;
1337
1338                         /*
1339                          * Don't use xwrite() here. It loops forever on EAGAIN,
1340                          * and we're in our own poll() loop here.
1341                          *
1342                          * Note that we lose xwrite()'s handling of MAX_IO_SIZE
1343                          * and EINTR, so we have to implement those ourselves.
1344                          */
1345                         len = write(io->fd, io->u.out.buf,
1346                                     io->u.out.len <= MAX_IO_SIZE ?
1347                                     io->u.out.len : MAX_IO_SIZE);
1348                         if (len < 0) {
1349                                 if (errno != EINTR && errno != EAGAIN &&
1350                                     errno != ENOSPC) {
1351                                         io->error = errno;
1352                                         close(io->fd);
1353                                         io->fd = -1;
1354                                 }
1355                         } else {
1356                                 io->u.out.buf += len;
1357                                 io->u.out.len -= len;
1358                                 if (!io->u.out.len) {
1359                                         close(io->fd);
1360                                         io->fd = -1;
1361                                 }
1362                         }
1363                 }
1364
1365                 if (io->type == POLLIN) {
1366                         ssize_t len = strbuf_read_once(io->u.in.buf,
1367                                                        io->fd, io->u.in.hint);
1368                         if (len < 0)
1369                                 io->error = errno;
1370                         if (len <= 0) {
1371                                 close(io->fd);
1372                                 io->fd = -1;
1373                         }
1374                 }
1375         }
1376
1377         return 1;
1378 }
1379
1380 static int pump_io(struct io_pump *slots, int nr)
1381 {
1382         struct pollfd *pfd;
1383         int i;
1384
1385         for (i = 0; i < nr; i++)
1386                 slots[i].error = 0;
1387
1388         ALLOC_ARRAY(pfd, nr);
1389         while (pump_io_round(slots, nr, pfd))
1390                 ; /* nothing */
1391         free(pfd);
1392
1393         /* There may be multiple errno values, so just pick the first. */
1394         for (i = 0; i < nr; i++) {
1395                 if (slots[i].error) {
1396                         errno = slots[i].error;
1397                         return -1;
1398                 }
1399         }
1400         return 0;
1401 }
1402
1403
1404 int pipe_command(struct child_process *cmd,
1405                  const char *in, size_t in_len,
1406                  struct strbuf *out, size_t out_hint,
1407                  struct strbuf *err, size_t err_hint)
1408 {
1409         struct io_pump io[3];
1410         int nr = 0;
1411
1412         if (in)
1413                 cmd->in = -1;
1414         if (out)
1415                 cmd->out = -1;
1416         if (err)
1417                 cmd->err = -1;
1418
1419         if (start_command(cmd) < 0)
1420                 return -1;
1421
1422         if (in) {
1423                 if (enable_pipe_nonblock(cmd->in) < 0) {
1424                         error_errno("unable to make pipe non-blocking");
1425                         close(cmd->in);
1426                         if (out)
1427                                 close(cmd->out);
1428                         if (err)
1429                                 close(cmd->err);
1430                         return -1;
1431                 }
1432                 io[nr].fd = cmd->in;
1433                 io[nr].type = POLLOUT;
1434                 io[nr].u.out.buf = in;
1435                 io[nr].u.out.len = in_len;
1436                 nr++;
1437         }
1438         if (out) {
1439                 io[nr].fd = cmd->out;
1440                 io[nr].type = POLLIN;
1441                 io[nr].u.in.buf = out;
1442                 io[nr].u.in.hint = out_hint;
1443                 nr++;
1444         }
1445         if (err) {
1446                 io[nr].fd = cmd->err;
1447                 io[nr].type = POLLIN;
1448                 io[nr].u.in.buf = err;
1449                 io[nr].u.in.hint = err_hint;
1450                 nr++;
1451         }
1452
1453         if (pump_io(io, nr) < 0) {
1454                 finish_command(cmd); /* throw away exit code */
1455                 return -1;
1456         }
1457
1458         return finish_command(cmd);
1459 }
1460
1461 enum child_state {
1462         GIT_CP_FREE,
1463         GIT_CP_WORKING,
1464         GIT_CP_WAIT_CLEANUP,
1465 };
1466
1467 struct parallel_processes {
1468         size_t nr_processes;
1469
1470         struct {
1471                 enum child_state state;
1472                 struct child_process process;
1473                 struct strbuf err;
1474                 void *data;
1475         } *children;
1476         /*
1477          * The struct pollfd is logically part of *children,
1478          * but the system call expects it as its own array.
1479          */
1480         struct pollfd *pfd;
1481
1482         unsigned shutdown : 1;
1483
1484         size_t output_owner;
1485         struct strbuf buffered_output; /* of finished children */
1486 };
1487
1488 struct parallel_processes_for_signal {
1489         const struct run_process_parallel_opts *opts;
1490         const struct parallel_processes *pp;
1491 };
1492
1493 static void kill_children(const struct parallel_processes *pp,
1494                           const struct run_process_parallel_opts *opts,
1495                           int signo)
1496 {
1497         for (size_t i = 0; i < opts->processes; i++)
1498                 if (pp->children[i].state == GIT_CP_WORKING)
1499                         kill(pp->children[i].process.pid, signo);
1500 }
1501
1502 static void kill_children_signal(const struct parallel_processes_for_signal *pp_sig,
1503                                  int signo)
1504 {
1505         kill_children(pp_sig->pp, pp_sig->opts, signo);
1506 }
1507
1508 static struct parallel_processes_for_signal *pp_for_signal;
1509
1510 static void handle_children_on_signal(int signo)
1511 {
1512         kill_children_signal(pp_for_signal, signo);
1513         sigchain_pop(signo);
1514         raise(signo);
1515 }
1516
1517 static void pp_init(struct parallel_processes *pp,
1518                     const struct run_process_parallel_opts *opts,
1519                     struct parallel_processes_for_signal *pp_sig)
1520 {
1521         const size_t n = opts->processes;
1522
1523         if (!n)
1524                 BUG("you must provide a non-zero number of processes!");
1525
1526         trace_printf("run_processes_parallel: preparing to run up to %"PRIuMAX" tasks",
1527                      (uintmax_t)n);
1528
1529         if (!opts->get_next_task)
1530                 BUG("you need to specify a get_next_task function");
1531
1532         CALLOC_ARRAY(pp->children, n);
1533         if (!opts->ungroup)
1534                 CALLOC_ARRAY(pp->pfd, n);
1535
1536         for (size_t i = 0; i < n; i++) {
1537                 strbuf_init(&pp->children[i].err, 0);
1538                 child_process_init(&pp->children[i].process);
1539                 if (pp->pfd) {
1540                         pp->pfd[i].events = POLLIN | POLLHUP;
1541                         pp->pfd[i].fd = -1;
1542                 }
1543         }
1544
1545         pp_sig->pp = pp;
1546         pp_sig->opts = opts;
1547         pp_for_signal = pp_sig;
1548         sigchain_push_common(handle_children_on_signal);
1549 }
1550
1551 static void pp_cleanup(struct parallel_processes *pp,
1552                        const struct run_process_parallel_opts *opts)
1553 {
1554         trace_printf("run_processes_parallel: done");
1555         for (size_t i = 0; i < opts->processes; i++) {
1556                 strbuf_release(&pp->children[i].err);
1557                 child_process_clear(&pp->children[i].process);
1558         }
1559
1560         free(pp->children);
1561         free(pp->pfd);
1562
1563         /*
1564          * When get_next_task added messages to the buffer in its last
1565          * iteration, the buffered output is non empty.
1566          */
1567         strbuf_write(&pp->buffered_output, stderr);
1568         strbuf_release(&pp->buffered_output);
1569
1570         sigchain_pop_common();
1571 }
1572
1573 /* returns
1574  *  0 if a new task was started.
1575  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1576  *    problem with starting a new command)
1577  * <0 no new job was started, user wishes to shutdown early. Use negative code
1578  *    to signal the children.
1579  */
1580 static int pp_start_one(struct parallel_processes *pp,
1581                         const struct run_process_parallel_opts *opts)
1582 {
1583         size_t i;
1584         int code;
1585
1586         for (i = 0; i < opts->processes; i++)
1587                 if (pp->children[i].state == GIT_CP_FREE)
1588                         break;
1589         if (i == opts->processes)
1590                 BUG("bookkeeping is hard");
1591
1592         /*
1593          * By default, do not inherit stdin from the parent process - otherwise,
1594          * all children would share stdin! Users may overwrite this to provide
1595          * something to the child's stdin by having their 'get_next_task'
1596          * callback assign 0 to .no_stdin and an appropriate integer to .in.
1597          */
1598         pp->children[i].process.no_stdin = 1;
1599
1600         code = opts->get_next_task(&pp->children[i].process,
1601                                    opts->ungroup ? NULL : &pp->children[i].err,
1602                                    opts->data,
1603                                    &pp->children[i].data);
1604         if (!code) {
1605                 if (!opts->ungroup) {
1606                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1607                         strbuf_reset(&pp->children[i].err);
1608                 }
1609                 return 1;
1610         }
1611         if (!opts->ungroup) {
1612                 pp->children[i].process.err = -1;
1613                 pp->children[i].process.stdout_to_stderr = 1;
1614         }
1615
1616         if (start_command(&pp->children[i].process)) {
1617                 if (opts->start_failure)
1618                         code = opts->start_failure(opts->ungroup ? NULL :
1619                                                    &pp->children[i].err,
1620                                                    opts->data,
1621                                                    pp->children[i].data);
1622                 else
1623                         code = 0;
1624
1625                 if (!opts->ungroup) {
1626                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1627                         strbuf_reset(&pp->children[i].err);
1628                 }
1629                 if (code)
1630                         pp->shutdown = 1;
1631                 return code;
1632         }
1633
1634         pp->nr_processes++;
1635         pp->children[i].state = GIT_CP_WORKING;
1636         if (pp->pfd)
1637                 pp->pfd[i].fd = pp->children[i].process.err;
1638         return 0;
1639 }
1640
1641 static void pp_buffer_stderr(struct parallel_processes *pp,
1642                              const struct run_process_parallel_opts *opts,
1643                              int output_timeout)
1644 {
1645         while (poll(pp->pfd, opts->processes, output_timeout) < 0) {
1646                 if (errno == EINTR)
1647                         continue;
1648                 pp_cleanup(pp, opts);
1649                 die_errno("poll");
1650         }
1651
1652         /* Buffer output from all pipes. */
1653         for (size_t i = 0; i < opts->processes; i++) {
1654                 if (pp->children[i].state == GIT_CP_WORKING &&
1655                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1656                         int n = strbuf_read_once(&pp->children[i].err,
1657                                                  pp->children[i].process.err, 0);
1658                         if (n == 0) {
1659                                 close(pp->children[i].process.err);
1660                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1661                         } else if (n < 0)
1662                                 if (errno != EAGAIN)
1663                                         die_errno("read");
1664                 }
1665         }
1666 }
1667
1668 static void pp_output(const struct parallel_processes *pp)
1669 {
1670         size_t i = pp->output_owner;
1671
1672         if (pp->children[i].state == GIT_CP_WORKING &&
1673             pp->children[i].err.len) {
1674                 strbuf_write(&pp->children[i].err, stderr);
1675                 strbuf_reset(&pp->children[i].err);
1676         }
1677 }
1678
1679 static int pp_collect_finished(struct parallel_processes *pp,
1680                                const struct run_process_parallel_opts *opts)
1681 {
1682         int code;
1683         size_t i;
1684         int result = 0;
1685
1686         while (pp->nr_processes > 0) {
1687                 for (i = 0; i < opts->processes; i++)
1688                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1689                                 break;
1690                 if (i == opts->processes)
1691                         break;
1692
1693                 code = finish_command(&pp->children[i].process);
1694
1695                 if (opts->task_finished)
1696                         code = opts->task_finished(code, opts->ungroup ? NULL :
1697                                                    &pp->children[i].err, opts->data,
1698                                                    pp->children[i].data);
1699                 else
1700                         code = 0;
1701
1702                 if (code)
1703                         result = code;
1704                 if (code < 0)
1705                         break;
1706
1707                 pp->nr_processes--;
1708                 pp->children[i].state = GIT_CP_FREE;
1709                 if (pp->pfd)
1710                         pp->pfd[i].fd = -1;
1711                 child_process_init(&pp->children[i].process);
1712
1713                 if (opts->ungroup) {
1714                         ; /* no strbuf_*() work to do here */
1715                 } else if (i != pp->output_owner) {
1716                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1717                         strbuf_reset(&pp->children[i].err);
1718                 } else {
1719                         const size_t n = opts->processes;
1720
1721                         strbuf_write(&pp->children[i].err, stderr);
1722                         strbuf_reset(&pp->children[i].err);
1723
1724                         /* Output all other finished child processes */
1725                         strbuf_write(&pp->buffered_output, stderr);
1726                         strbuf_reset(&pp->buffered_output);
1727
1728                         /*
1729                          * Pick next process to output live.
1730                          * NEEDSWORK:
1731                          * For now we pick it randomly by doing a round
1732                          * robin. Later we may want to pick the one with
1733                          * the most output or the longest or shortest
1734                          * running process time.
1735                          */
1736                         for (i = 0; i < n; i++)
1737                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1738                                         break;
1739                         pp->output_owner = (pp->output_owner + i) % n;
1740                 }
1741         }
1742         return result;
1743 }
1744
1745 void run_processes_parallel(const struct run_process_parallel_opts *opts)
1746 {
1747         int i, code;
1748         int output_timeout = 100;
1749         int spawn_cap = 4;
1750         struct parallel_processes_for_signal pp_sig;
1751         struct parallel_processes pp = {
1752                 .buffered_output = STRBUF_INIT,
1753         };
1754         /* options */
1755         const char *tr2_category = opts->tr2_category;
1756         const char *tr2_label = opts->tr2_label;
1757         const int do_trace2 = tr2_category && tr2_label;
1758
1759         if (do_trace2)
1760                 trace2_region_enter_printf(tr2_category, tr2_label, NULL,
1761                                            "max:%"PRIuMAX,
1762                                            (uintmax_t)opts->processes);
1763
1764         pp_init(&pp, opts, &pp_sig);
1765         while (1) {
1766                 for (i = 0;
1767                     i < spawn_cap && !pp.shutdown &&
1768                     pp.nr_processes < opts->processes;
1769                     i++) {
1770                         code = pp_start_one(&pp, opts);
1771                         if (!code)
1772                                 continue;
1773                         if (code < 0) {
1774                                 pp.shutdown = 1;
1775                                 kill_children(&pp, opts, -code);
1776                         }
1777                         break;
1778                 }
1779                 if (!pp.nr_processes)
1780                         break;
1781                 if (opts->ungroup) {
1782                         for (size_t i = 0; i < opts->processes; i++)
1783                                 pp.children[i].state = GIT_CP_WAIT_CLEANUP;
1784                 } else {
1785                         pp_buffer_stderr(&pp, opts, output_timeout);
1786                         pp_output(&pp);
1787                 }
1788                 code = pp_collect_finished(&pp, opts);
1789                 if (code) {
1790                         pp.shutdown = 1;
1791                         if (code < 0)
1792                                 kill_children(&pp, opts,-code);
1793                 }
1794         }
1795
1796         pp_cleanup(&pp, opts);
1797
1798         if (do_trace2)
1799                 trace2_region_leave(tr2_category, tr2_label, NULL);
1800 }
1801
1802 int prepare_auto_maintenance(int quiet, struct child_process *maint)
1803 {
1804         int enabled;
1805
1806         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1807             !enabled)
1808                 return 0;
1809
1810         maint->git_cmd = 1;
1811         maint->close_object_store = 1;
1812         strvec_pushl(&maint->args, "maintenance", "run", "--auto", NULL);
1813         strvec_push(&maint->args, quiet ? "--quiet" : "--no-quiet");
1814
1815         return 1;
1816 }
1817
1818 int run_auto_maintenance(int quiet)
1819 {
1820         struct child_process maint = CHILD_PROCESS_INIT;
1821         if (!prepare_auto_maintenance(quiet, &maint))
1822                 return 0;
1823         return run_command(&maint);
1824 }
1825
1826 void prepare_other_repo_env(struct strvec *env, const char *new_git_dir)
1827 {
1828         const char * const *var;
1829
1830         for (var = local_repo_env; *var; var++) {
1831                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1832                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1833                         strvec_push(env, *var);
1834         }
1835         strvec_pushf(env, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1836 }
1837
1838 enum start_bg_result start_bg_command(struct child_process *cmd,
1839                                       start_bg_wait_cb *wait_cb,
1840                                       void *cb_data,
1841                                       unsigned int timeout_sec)
1842 {
1843         enum start_bg_result sbgr = SBGR_ERROR;
1844         int ret;
1845         int wait_status;
1846         pid_t pid_seen;
1847         time_t time_limit;
1848
1849         /*
1850          * We do not allow clean-on-exit because the child process
1851          * should persist in the background and possibly/probably
1852          * after this process exits.  So we don't want to kill the
1853          * child during our atexit routine.
1854          */
1855         if (cmd->clean_on_exit)
1856                 BUG("start_bg_command() does not allow non-zero clean_on_exit");
1857
1858         if (!cmd->trace2_child_class)
1859                 cmd->trace2_child_class = "background";
1860
1861         ret = start_command(cmd);
1862         if (ret) {
1863                 /*
1864                  * We assume that if `start_command()` fails, we
1865                  * either get a complete `trace2_child_start() /
1866                  * trace2_child_exit()` pair or it fails before the
1867                  * `trace2_child_start()` is emitted, so we do not
1868                  * need to worry about it here.
1869                  *
1870                  * We also assume that `start_command()` does not add
1871                  * us to the cleanup list.  And that it calls
1872                  * `child_process_clear()`.
1873                  */
1874                 sbgr = SBGR_ERROR;
1875                 goto done;
1876         }
1877
1878         time(&time_limit);
1879         time_limit += timeout_sec;
1880
1881 wait:
1882         pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
1883
1884         if (!pid_seen) {
1885                 /*
1886                  * The child is currently running.  Ask the callback
1887                  * if the child is ready to do work or whether we
1888                  * should keep waiting for it to boot up.
1889                  */
1890                 ret = (*wait_cb)(cmd, cb_data);
1891                 if (!ret) {
1892                         /*
1893                          * The child is running and "ready".
1894                          */
1895                         trace2_child_ready(cmd, "ready");
1896                         sbgr = SBGR_READY;
1897                         goto done;
1898                 } else if (ret > 0) {
1899                         /*
1900                          * The callback said to give it more time to boot up
1901                          * (subject to our timeout limit).
1902                          */
1903                         time_t now;
1904
1905                         time(&now);
1906                         if (now < time_limit)
1907                                 goto wait;
1908
1909                         /*
1910                          * Our timeout has expired.  We don't try to
1911                          * kill the child, but rather let it continue
1912                          * (hopefully) trying to startup.
1913                          */
1914                         trace2_child_ready(cmd, "timeout");
1915                         sbgr = SBGR_TIMEOUT;
1916                         goto done;
1917                 } else {
1918                         /*
1919                          * The cb gave up on this child.  It is still running,
1920                          * but our cb got an error trying to probe it.
1921                          */
1922                         trace2_child_ready(cmd, "error");
1923                         sbgr = SBGR_CB_ERROR;
1924                         goto done;
1925                 }
1926         }
1927
1928         else if (pid_seen == cmd->pid) {
1929                 int child_code = -1;
1930
1931                 /*
1932                  * The child started, but exited or was terminated
1933                  * before becoming "ready".
1934                  *
1935                  * We try to match the behavior of `wait_or_whine()`
1936                  * WRT the handling of WIFSIGNALED() and WIFEXITED()
1937                  * and convert the child's status to a return code for
1938                  * tracing purposes and emit the `trace2_child_exit()`
1939                  * event.
1940                  *
1941                  * We do not want the wait_or_whine() error message
1942                  * because we will be called by client-side library
1943                  * routines.
1944                  */
1945                 if (WIFEXITED(wait_status))
1946                         child_code = WEXITSTATUS(wait_status);
1947                 else if (WIFSIGNALED(wait_status))
1948                         child_code = WTERMSIG(wait_status) + 128;
1949                 trace2_child_exit(cmd, child_code);
1950
1951                 sbgr = SBGR_DIED;
1952                 goto done;
1953         }
1954
1955         else if (pid_seen < 0 && errno == EINTR)
1956                 goto wait;
1957
1958         trace2_child_exit(cmd, -1);
1959         sbgr = SBGR_ERROR;
1960
1961 done:
1962         child_process_clear(cmd);
1963         invalidate_lstat_cache();
1964         return sbgr;
1965 }