run-command.c

   1 #include "git-compat-util.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 "symlinks.h"
   9 #include "thread-utils.h"
  10 #include "strbuf.h"
  11 #include "string-list.h"
  12 #include "trace.h"
  13 #include "trace2.h"
  14 #include "quote.h"
  15 #include "config.h"
  16 #include "packfile.h"
  17 #include "hook.h"
  18 #include "compat/nonblock.h"
  19 #include "alloc.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 /*
 174  * Search $PATH for a command.  This emulates the path search that
 175  * execvp would perform, without actually executing the command so it
 176  * can be used before fork() to prepare to run a command using
 177  * execve() or after execvp() to diagnose why it failed.
 178  *
 179  * The caller should ensure that file contains no directory
 180  * separators.
 181  *
 182  * Returns the path to the command, as found in $PATH or NULL if the
 183  * command could not be found.  The caller inherits ownership of the memory
 184  * used to store the resultant path.
 185  *
 186  * This should not be used on Windows, where the $PATH search rules
 187  * are more complicated (e.g., a search for "foo" should find
 188  * "foo.exe").
 189  */
 190 static char *locate_in_PATH(const char *file)
 191 {
 192         const char *p = getenv("PATH");
 193         struct strbuf buf = STRBUF_INIT;
 194
 195         if (!p || !*p)
 196                 return NULL;
 197
 198         while (1) {
 199                 const char *end = strchrnul(p, ':');
 200
 201                 strbuf_reset(&buf);
 202
 203                 /* POSIX specifies an empty entry as the current directory. */
 204                 if (end != p) {
 205                         strbuf_add(&buf, p, end - p);
 206                         strbuf_addch(&buf, '/');
 207                 }
 208                 strbuf_addstr(&buf, file);
 209
 210                 if (is_executable(buf.buf))
 211                         return strbuf_detach(&buf, NULL);
 212
 213                 if (!*end)
 214                         break;
 215                 p = end + 1;
 216         }
 217
 218         strbuf_release(&buf);
 219         return NULL;
 220 }
 221
 222 int exists_in_PATH(const char *command)
 223 {
 224         char *r = locate_in_PATH(command);
 225         int found = r != NULL;
 226         free(r);
 227         return found;
 228 }
 229
 230 int sane_execvp(const char *file, char * const argv[])
 231 {
 232 #ifndef GIT_WINDOWS_NATIVE
 233         /*
 234          * execvp() doesn't return, so we all we can do is tell trace2
 235          * what we are about to do and let it leave a hint in the log
 236          * (unless of course the execvp() fails).
 237          *
 238          * we skip this for Windows because the compat layer already
 239          * has to emulate the execvp() call anyway.
 240          */
 241         int exec_id = trace2_exec(file, (const char **)argv);
 242 #endif
 243
 244         if (!execvp(file, argv))
 245                 return 0; /* cannot happen ;-) */
 246
 247 #ifndef GIT_WINDOWS_NATIVE
 248         {
 249                 int ec = errno;
 250                 trace2_exec_result(exec_id, ec);
 251                 errno = ec;
 252         }
 253 #endif
 254
 255         /*
 256          * When a command can't be found because one of the directories
 257          * listed in $PATH is unsearchable, execvp reports EACCES, but
 258          * careful usability testing (read: analysis of occasional bug
 259          * reports) reveals that "No such file or directory" is more
 260          * intuitive.
 261          *
 262          * We avoid commands with "/", because execvp will not do $PATH
 263          * lookups in that case.
 264          *
 265          * The reassignment of EACCES to errno looks like a no-op below,
 266          * but we need to protect against exists_in_PATH overwriting errno.
 267          */
 268         if (errno == EACCES && !strchr(file, '/'))
 269                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 270         else if (errno == ENOTDIR && !strchr(file, '/'))
 271                 errno = ENOENT;
 272         return -1;
 273 }
 274
 275 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 276 {
 277         if (!argv[0])
 278                 BUG("shell command is empty");
 279
 280         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 281 #ifndef GIT_WINDOWS_NATIVE
 282                 strvec_push(out, SHELL_PATH);
 283 #else
 284                 strvec_push(out, "sh");
 285 #endif
 286                 strvec_push(out, "-c");
 287
 288                 /*
 289                  * If we have no extra arguments, we do not even need to
 290                  * bother with the "$@" magic.
 291                  */
 292                 if (!argv[1])
 293                         strvec_push(out, argv[0]);
 294                 else
 295                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 296         }
 297
 298         strvec_pushv(out, argv);
 299         return out->v;
 300 }
 301
 302 #ifndef GIT_WINDOWS_NATIVE
 303 static int child_notifier = -1;
 304
 305 enum child_errcode {
 306         CHILD_ERR_CHDIR,
 307         CHILD_ERR_DUP2,
 308         CHILD_ERR_CLOSE,
 309         CHILD_ERR_SIGPROCMASK,
 310         CHILD_ERR_ENOENT,
 311         CHILD_ERR_SILENT,
 312         CHILD_ERR_ERRNO
 313 };
 314
 315 struct child_err {
 316         enum child_errcode err;
 317         int syserr; /* errno */
 318 };
 319
 320 static void child_die(enum child_errcode err)
 321 {
 322         struct child_err buf;
 323
 324         buf.err = err;
 325         buf.syserr = errno;
 326
 327         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 328         xwrite(child_notifier, &buf, sizeof(buf));
 329         _exit(1);
 330 }
 331
 332 static void child_dup2(int fd, int to)
 333 {
 334         if (dup2(fd, to) < 0)
 335                 child_die(CHILD_ERR_DUP2);
 336 }
 337
 338 static void child_close(int fd)
 339 {
 340         if (close(fd))
 341                 child_die(CHILD_ERR_CLOSE);
 342 }
 343
 344 static void child_close_pair(int fd[2])
 345 {
 346         child_close(fd[0]);
 347         child_close(fd[1]);
 348 }
 349
 350 static void child_error_fn(const char *err UNUSED, va_list params UNUSED)
 351 {
 352         const char msg[] = "error() should not be called in child\n";
 353         xwrite(2, msg, sizeof(msg) - 1);
 354 }
 355
 356 static void child_warn_fn(const char *err UNUSED, va_list params UNUSED)
 357 {
 358         const char msg[] = "warn() should not be called in child\n";
 359         xwrite(2, msg, sizeof(msg) - 1);
 360 }
 361
 362 static void NORETURN child_die_fn(const char *err UNUSED, va_list params UNUSED)
 363 {
 364         const char msg[] = "die() should not be called in child\n";
 365         xwrite(2, msg, sizeof(msg) - 1);
 366         _exit(2);
 367 }
 368
 369 /* this runs in the parent process */
 370 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 371 {
 372         static void (*old_errfn)(const char *err, va_list params);
 373         report_fn die_message_routine = get_die_message_routine();
 374
 375         old_errfn = get_error_routine();
 376         set_error_routine(die_message_routine);
 377         errno = cerr->syserr;
 378
 379         switch (cerr->err) {
 380         case CHILD_ERR_CHDIR:
 381                 error_errno("exec '%s': cd to '%s' failed",
 382                             cmd->args.v[0], cmd->dir);
 383                 break;
 384         case CHILD_ERR_DUP2:
 385                 error_errno("dup2() in child failed");
 386                 break;
 387         case CHILD_ERR_CLOSE:
 388                 error_errno("close() in child failed");
 389                 break;
 390         case CHILD_ERR_SIGPROCMASK:
 391                 error_errno("sigprocmask failed restoring signals");
 392                 break;
 393         case CHILD_ERR_ENOENT:
 394                 error_errno("cannot run %s", cmd->args.v[0]);
 395                 break;
 396         case CHILD_ERR_SILENT:
 397                 break;
 398         case CHILD_ERR_ERRNO:
 399                 error_errno("cannot exec '%s'", cmd->args.v[0]);
 400                 break;
 401         }
 402         set_error_routine(old_errfn);
 403 }
 404
 405 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 406 {
 407         if (!cmd->args.v[0])
 408                 BUG("command is empty");
 409
 410         /*
 411          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 412          * attempt to interpret the command with 'sh'.
 413          */
 414         strvec_push(out, SHELL_PATH);
 415
 416         if (cmd->git_cmd) {
 417                 prepare_git_cmd(out, cmd->args.v);
 418         } else if (cmd->use_shell) {
 419                 prepare_shell_cmd(out, cmd->args.v);
 420         } else {
 421                 strvec_pushv(out, cmd->args.v);
 422         }
 423
 424         /*
 425          * If there are no dir separator characters in the command then perform
 426          * a path lookup and use the resolved path as the command to exec. If
 427          * there are dir separator characters, we have exec attempt to invoke
 428          * the command directly.
 429          */
 430         if (!has_dir_sep(out->v[1])) {
 431                 char *program = locate_in_PATH(out->v[1]);
 432                 if (program) {
 433                         free((char *)out->v[1]);
 434                         out->v[1] = program;
 435                 } else {
 436                         strvec_clear(out);
 437                         errno = ENOENT;
 438                         return -1;
 439                 }
 440         }
 441
 442         return 0;
 443 }
 444
 445 static char **prep_childenv(const char *const *deltaenv)
 446 {
 447         extern char **environ;
 448         char **childenv;
 449         struct string_list env = STRING_LIST_INIT_DUP;
 450         struct strbuf key = STRBUF_INIT;
 451         const char *const *p;
 452         int i;
 453
 454         /* Construct a sorted string list consisting of the current environ */
 455         for (p = (const char *const *) environ; p && *p; p++) {
 456                 const char *equals = strchr(*p, '=');
 457
 458                 if (equals) {
 459                         strbuf_reset(&key);
 460                         strbuf_add(&key, *p, equals - *p);
 461                         string_list_append(&env, key.buf)->util = (void *) *p;
 462                 } else {
 463                         string_list_append(&env, *p)->util = (void *) *p;
 464                 }
 465         }
 466         string_list_sort(&env);
 467
 468         /* Merge in 'deltaenv' with the current environ */
 469         for (p = deltaenv; p && *p; p++) {
 470                 const char *equals = strchr(*p, '=');
 471
 472                 if (equals) {
 473                         /* ('key=value'), insert or replace entry */
 474                         strbuf_reset(&key);
 475                         strbuf_add(&key, *p, equals - *p);
 476                         string_list_insert(&env, key.buf)->util = (void *) *p;
 477                 } else {
 478                         /* otherwise ('key') remove existing entry */
 479                         string_list_remove(&env, *p, 0);
 480                 }
 481         }
 482
 483         /* Create an array of 'char *' to be used as the childenv */
 484         ALLOC_ARRAY(childenv, env.nr + 1);
 485         for (i = 0; i < env.nr; i++)
 486                 childenv[i] = env.items[i].util;
 487         childenv[env.nr] = NULL;
 488
 489         string_list_clear(&env, 0);
 490         strbuf_release(&key);
 491         return childenv;
 492 }
 493
 494 struct atfork_state {
 495 #ifndef NO_PTHREADS
 496         int cs;
 497 #endif
 498         sigset_t old;
 499 };
 500
 501 #define CHECK_BUG(err, msg) \
 502         do { \
 503                 int e = (err); \
 504                 if (e) \
 505                         BUG("%s: %s", msg, strerror(e)); \
 506         } while(0)
 507
 508 static void atfork_prepare(struct atfork_state *as)
 509 {
 510         sigset_t all;
 511
 512         if (sigfillset(&all))
 513                 die_errno("sigfillset");
 514 #ifdef NO_PTHREADS
 515         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 516                 die_errno("sigprocmask");
 517 #else
 518         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 519                 "blocking all signals");
 520         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 521                 "disabling cancellation");
 522 #endif
 523 }
 524
 525 static void atfork_parent(struct atfork_state *as)
 526 {
 527 #ifdef NO_PTHREADS
 528         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 529                 die_errno("sigprocmask");
 530 #else
 531         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 532                 "re-enabling cancellation");
 533         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 534                 "restoring signal mask");
 535 #endif
 536 }
 537 #endif /* GIT_WINDOWS_NATIVE */
 538
 539 static inline void set_cloexec(int fd)
 540 {
 541         int flags = fcntl(fd, F_GETFD);
 542         if (flags >= 0)
 543                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 544 }
 545
 546 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 547 {
 548         int status, code = -1;
 549         pid_t waiting;
 550         int failed_errno = 0;
 551
 552         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 553                 ;       /* nothing */
 554
 555         if (waiting < 0) {
 556                 failed_errno = errno;
 557                 if (!in_signal)
 558                         error_errno("waitpid for %s failed", argv0);
 559         } else if (waiting != pid) {
 560                 if (!in_signal)
 561                         error("waitpid is confused (%s)", argv0);
 562         } else if (WIFSIGNALED(status)) {
 563                 code = WTERMSIG(status);
 564                 if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 565                         error("%s died of signal %d", argv0, code);
 566                 /*
 567                  * This return value is chosen so that code & 0xff
 568                  * mimics the exit code that a POSIX shell would report for
 569                  * a program that died from this signal.
 570                  */
 571                 code += 128;
 572         } else if (WIFEXITED(status)) {
 573                 code = WEXITSTATUS(status);
 574         } else {
 575                 if (!in_signal)
 576                         error("waitpid is confused (%s)", argv0);
 577         }
 578
 579         if (!in_signal)
 580                 clear_child_for_cleanup(pid);
 581
 582         errno = failed_errno;
 583         return code;
 584 }
 585
 586 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 587 {
 588         struct string_list envs = STRING_LIST_INIT_DUP;
 589         const char *const *e;
 590         int i;
 591         int printed_unset = 0;
 592
 593         /* Last one wins, see run-command.c:prep_childenv() for context */
 594         for (e = deltaenv; e && *e; e++) {
 595                 struct strbuf key = STRBUF_INIT;
 596                 char *equals = strchr(*e, '=');
 597
 598                 if (equals) {
 599                         strbuf_add(&key, *e, equals - *e);
 600                         string_list_insert(&envs, key.buf)->util = equals + 1;
 601                 } else {
 602                         string_list_insert(&envs, *e)->util = NULL;
 603                 }
 604                 strbuf_release(&key);
 605         }
 606
 607         /* "unset X Y...;" */
 608         for (i = 0; i < envs.nr; i++) {
 609                 const char *var = envs.items[i].string;
 610                 const char *val = envs.items[i].util;
 611
 612                 if (val || !getenv(var))
 613                         continue;
 614
 615                 if (!printed_unset) {
 616                         strbuf_addstr(dst, " unset");
 617                         printed_unset = 1;
 618                 }
 619                 strbuf_addf(dst, " %s", var);
 620         }
 621         if (printed_unset)
 622                 strbuf_addch(dst, ';');
 623
 624         /* ... followed by "A=B C=D ..." */
 625         for (i = 0; i < envs.nr; i++) {
 626                 const char *var = envs.items[i].string;
 627                 const char *val = envs.items[i].util;
 628                 const char *oldval;
 629
 630                 if (!val)
 631                         continue;
 632
 633                 oldval = getenv(var);
 634                 if (oldval && !strcmp(val, oldval))
 635                         continue;
 636
 637                 strbuf_addf(dst, " %s=", var);
 638                 sq_quote_buf_pretty(dst, val);
 639         }
 640         string_list_clear(&envs, 0);
 641 }
 642
 643 static void trace_run_command(const struct child_process *cp)
 644 {
 645         struct strbuf buf = STRBUF_INIT;
 646
 647         if (!trace_want(&trace_default_key))
 648                 return;
 649
 650         strbuf_addstr(&buf, "trace: run_command:");
 651         if (cp->dir) {
 652                 strbuf_addstr(&buf, " cd ");
 653                 sq_quote_buf_pretty(&buf, cp->dir);
 654                 strbuf_addch(&buf, ';');
 655         }
 656         trace_add_env(&buf, cp->env.v);
 657         if (cp->git_cmd)
 658                 strbuf_addstr(&buf, " git");
 659         sq_quote_argv_pretty(&buf, cp->args.v);
 660
 661         trace_printf("%s", buf.buf);
 662         strbuf_release(&buf);
 663 }
 664
 665 int start_command(struct child_process *cmd)
 666 {
 667         int need_in, need_out, need_err;
 668         int fdin[2], fdout[2], fderr[2];
 669         int failed_errno;
 670         char *str;
 671
 672         /*
 673          * In case of errors we must keep the promise to close FDs
 674          * that have been passed in via ->in and ->out.
 675          */
 676
 677         need_in = !cmd->no_stdin && cmd->in < 0;
 678         if (need_in) {
 679                 if (pipe(fdin) < 0) {
 680                         failed_errno = errno;
 681                         if (cmd->out > 0)
 682                                 close(cmd->out);
 683                         str = "standard input";
 684                         goto fail_pipe;
 685                 }
 686                 cmd->in = fdin[1];
 687         }
 688
 689         need_out = !cmd->no_stdout
 690                 && !cmd->stdout_to_stderr
 691                 && cmd->out < 0;
 692         if (need_out) {
 693                 if (pipe(fdout) < 0) {
 694                         failed_errno = errno;
 695                         if (need_in)
 696                                 close_pair(fdin);
 697                         else if (cmd->in)
 698                                 close(cmd->in);
 699                         str = "standard output";
 700                         goto fail_pipe;
 701                 }
 702                 cmd->out = fdout[0];
 703         }
 704
 705         need_err = !cmd->no_stderr && cmd->err < 0;
 706         if (need_err) {
 707                 if (pipe(fderr) < 0) {
 708                         failed_errno = errno;
 709                         if (need_in)
 710                                 close_pair(fdin);
 711                         else if (cmd->in)
 712                                 close(cmd->in);
 713                         if (need_out)
 714                                 close_pair(fdout);
 715                         else if (cmd->out)
 716                                 close(cmd->out);
 717                         str = "standard error";
 718 fail_pipe:
 719                         error("cannot create %s pipe for %s: %s",
 720                                 str, cmd->args.v[0], strerror(failed_errno));
 721                         child_process_clear(cmd);
 722                         errno = failed_errno;
 723                         return -1;
 724                 }
 725                 cmd->err = fderr[0];
 726         }
 727
 728         trace2_child_start(cmd);
 729         trace_run_command(cmd);
 730
 731         fflush(NULL);
 732
 733         if (cmd->close_object_store)
 734                 close_object_store(the_repository->objects);
 735
 736 #ifndef GIT_WINDOWS_NATIVE
 737 {
 738         int notify_pipe[2];
 739         int null_fd = -1;
 740         char **childenv;
 741         struct strvec argv = STRVEC_INIT;
 742         struct child_err cerr;
 743         struct atfork_state as;
 744
 745         if (prepare_cmd(&argv, cmd) < 0) {
 746                 failed_errno = errno;
 747                 cmd->pid = -1;
 748                 if (!cmd->silent_exec_failure)
 749                         error_errno("cannot run %s", cmd->args.v[0]);
 750                 goto end_of_spawn;
 751         }
 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 (errno == ENOENT) {
 850                         if (cmd->silent_exec_failure)
 851                                 child_die(CHILD_ERR_SILENT);
 852                         child_die(CHILD_ERR_ENOENT);
 853                 } else {
 854                         child_die(CHILD_ERR_ERRNO);
 855                 }
 856         }
 857         atfork_parent(&as);
 858         if (cmd->pid < 0)
 859                 error_errno("cannot fork() for %s", cmd->args.v[0]);
 860         else if (cmd->clean_on_exit)
 861                 mark_child_for_cleanup(cmd->pid, cmd);
 862
 863         /*
 864          * Wait for child's exec. If the exec succeeds (or if fork()
 865          * failed), EOF is seen immediately by the parent. Otherwise, the
 866          * child process sends a child_err struct.
 867          * Note that use of this infrastructure is completely advisory,
 868          * therefore, we keep error checks minimal.
 869          */
 870         close(notify_pipe[1]);
 871         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 872                 /*
 873                  * At this point we know that fork() succeeded, but exec()
 874                  * failed. Errors have been reported to our stderr.
 875                  */
 876                 wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 877                 child_err_spew(cmd, &cerr);
 878                 failed_errno = errno;
 879                 cmd->pid = -1;
 880         }
 881         close(notify_pipe[0]);
 882
 883         if (null_fd >= 0)
 884                 close(null_fd);
 885         strvec_clear(&argv);
 886         free(childenv);
 887 }
 888 end_of_spawn:
 889
 890 #else
 891 {
 892         int fhin = 0, fhout = 1, fherr = 2;
 893         const char **sargv = cmd->args.v;
 894         struct strvec nargv = STRVEC_INIT;
 895
 896         if (cmd->no_stdin)
 897                 fhin = open("/dev/null", O_RDWR);
 898         else if (need_in)
 899                 fhin = dup(fdin[0]);
 900         else if (cmd->in)
 901                 fhin = dup(cmd->in);
 902
 903         if (cmd->no_stderr)
 904                 fherr = open("/dev/null", O_RDWR);
 905         else if (need_err)
 906                 fherr = dup(fderr[1]);
 907         else if (cmd->err > 2)
 908                 fherr = dup(cmd->err);
 909
 910         if (cmd->no_stdout)
 911                 fhout = open("/dev/null", O_RDWR);
 912         else if (cmd->stdout_to_stderr)
 913                 fhout = dup(fherr);
 914         else if (need_out)
 915                 fhout = dup(fdout[1]);
 916         else if (cmd->out > 1)
 917                 fhout = dup(cmd->out);
 918
 919         if (cmd->git_cmd)
 920                 cmd->args.v = prepare_git_cmd(&nargv, sargv);
 921         else if (cmd->use_shell)
 922                 cmd->args.v = prepare_shell_cmd(&nargv, sargv);
 923
 924         cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v,
 925                                   (char**) cmd->env.v,
 926                                   cmd->dir, fhin, fhout, fherr);
 927         failed_errno = errno;
 928         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 929                 error_errno("cannot spawn %s", cmd->args.v[0]);
 930         if (cmd->clean_on_exit && cmd->pid >= 0)
 931                 mark_child_for_cleanup(cmd->pid, cmd);
 932
 933         strvec_clear(&nargv);
 934         cmd->args.v = sargv;
 935         if (fhin != 0)
 936                 close(fhin);
 937         if (fhout != 1)
 938                 close(fhout);
 939         if (fherr != 2)
 940                 close(fherr);
 941 }
 942 #endif
 943
 944         if (cmd->pid < 0) {
 945                 trace2_child_exit(cmd, -1);
 946
 947                 if (need_in)
 948                         close_pair(fdin);
 949                 else if (cmd->in)
 950                         close(cmd->in);
 951                 if (need_out)
 952                         close_pair(fdout);
 953                 else if (cmd->out)
 954                         close(cmd->out);
 955                 if (need_err)
 956                         close_pair(fderr);
 957                 else if (cmd->err)
 958                         close(cmd->err);
 959                 child_process_clear(cmd);
 960                 errno = failed_errno;
 961                 return -1;
 962         }
 963
 964         if (need_in)
 965                 close(fdin[0]);
 966         else if (cmd->in)
 967                 close(cmd->in);
 968
 969         if (need_out)
 970                 close(fdout[1]);
 971         else if (cmd->out)
 972                 close(cmd->out);
 973
 974         if (need_err)
 975                 close(fderr[1]);
 976         else if (cmd->err)
 977                 close(cmd->err);
 978
 979         return 0;
 980 }
 981
 982 int finish_command(struct child_process *cmd)
 983 {
 984         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 985         trace2_child_exit(cmd, ret);
 986         child_process_clear(cmd);
 987         invalidate_lstat_cache();
 988         return ret;
 989 }
 990
 991 int finish_command_in_signal(struct child_process *cmd)
 992 {
 993         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
 994         if (ret != -1)
 995                 trace2_child_exit(cmd, ret);
 996         return ret;
 997 }
 998
 999
1000 int run_command(struct child_process *cmd)
1001 {
1002         int code;
1003
1004         if (cmd->out < 0 || cmd->err < 0)
1005                 BUG("run_command with a pipe can cause deadlock");
1006
1007         code = start_command(cmd);
1008         if (code)
1009                 return code;
1010         return finish_command(cmd);
1011 }
1012
1013 #ifndef NO_PTHREADS
1014 static pthread_t main_thread;
1015 static int main_thread_set;
1016 static pthread_key_t async_key;
1017 static pthread_key_t async_die_counter;
1018
1019 static void *run_thread(void *data)
1020 {
1021         struct async *async = data;
1022         intptr_t ret;
1023
1024         if (async->isolate_sigpipe) {
1025                 sigset_t mask;
1026                 sigemptyset(&mask);
1027                 sigaddset(&mask, SIGPIPE);
1028                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL)) {
1029                         ret = error("unable to block SIGPIPE in async thread");
1030                         return (void *)ret;
1031                 }
1032         }
1033
1034         pthread_setspecific(async_key, async);
1035         ret = async->proc(async->proc_in, async->proc_out, async->data);
1036         return (void *)ret;
1037 }
1038
1039 static NORETURN void die_async(const char *err, va_list params)
1040 {
1041         report_fn die_message_fn = get_die_message_routine();
1042
1043         die_message_fn(err, params);
1044
1045         if (in_async()) {
1046                 struct async *async = pthread_getspecific(async_key);
1047                 if (async->proc_in >= 0)
1048                         close(async->proc_in);
1049                 if (async->proc_out >= 0)
1050                         close(async->proc_out);
1051                 pthread_exit((void *)128);
1052         }
1053
1054         exit(128);
1055 }
1056
1057 static int async_die_is_recursing(void)
1058 {
1059         void *ret = pthread_getspecific(async_die_counter);
1060         pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
1061         return ret != NULL;
1062 }
1063
1064 int in_async(void)
1065 {
1066         if (!main_thread_set)
1067                 return 0; /* no asyncs started yet */
1068         return !pthread_equal(main_thread, pthread_self());
1069 }
1070
1071 static void NORETURN async_exit(int code)
1072 {
1073         pthread_exit((void *)(intptr_t)code);
1074 }
1075
1076 #else
1077
1078 static struct {
1079         void (**handlers)(void);
1080         size_t nr;
1081         size_t alloc;
1082 } git_atexit_hdlrs;
1083
1084 static int git_atexit_installed;
1085
1086 static void git_atexit_dispatch(void)
1087 {
1088         size_t i;
1089
1090         for (i=git_atexit_hdlrs.nr ; i ; i--)
1091                 git_atexit_hdlrs.handlers[i-1]();
1092 }
1093
1094 static void git_atexit_clear(void)
1095 {
1096         free(git_atexit_hdlrs.handlers);
1097         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1098         git_atexit_installed = 0;
1099 }
1100
1101 #undef atexit
1102 int git_atexit(void (*handler)(void))
1103 {
1104         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1105         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1106         if (!git_atexit_installed) {
1107                 if (atexit(&git_atexit_dispatch))
1108                         return -1;
1109                 git_atexit_installed = 1;
1110         }
1111         return 0;
1112 }
1113 #define atexit git_atexit
1114
1115 static int process_is_async;
1116 int in_async(void)
1117 {
1118         return process_is_async;
1119 }
1120
1121 static void NORETURN async_exit(int code)
1122 {
1123         exit(code);
1124 }
1125
1126 #endif
1127
1128 void check_pipe(int err)
1129 {
1130         if (err == EPIPE) {
1131                 if (in_async())
1132                         async_exit(141);
1133
1134                 signal(SIGPIPE, SIG_DFL);
1135                 raise(SIGPIPE);
1136                 /* Should never happen, but just in case... */
1137                 exit(141);
1138         }
1139 }
1140
1141 int start_async(struct async *async)
1142 {
1143         int need_in, need_out;
1144         int fdin[2], fdout[2];
1145         int proc_in, proc_out;
1146
1147         need_in = async->in < 0;
1148         if (need_in) {
1149                 if (pipe(fdin) < 0) {
1150                         if (async->out > 0)
1151                                 close(async->out);
1152                         return error_errno("cannot create pipe");
1153                 }
1154                 async->in = fdin[1];
1155         }
1156
1157         need_out = async->out < 0;
1158         if (need_out) {
1159                 if (pipe(fdout) < 0) {
1160                         if (need_in)
1161                                 close_pair(fdin);
1162                         else if (async->in)
1163                                 close(async->in);
1164                         return error_errno("cannot create pipe");
1165                 }
1166                 async->out = fdout[0];
1167         }
1168
1169         if (need_in)
1170                 proc_in = fdin[0];
1171         else if (async->in)
1172                 proc_in = async->in;
1173         else
1174                 proc_in = -1;
1175
1176         if (need_out)
1177                 proc_out = fdout[1];
1178         else if (async->out)
1179                 proc_out = async->out;
1180         else
1181                 proc_out = -1;
1182
1183 #ifdef NO_PTHREADS
1184         /* Flush stdio before fork() to avoid cloning buffers */
1185         fflush(NULL);
1186
1187         async->pid = fork();
1188         if (async->pid < 0) {
1189                 error_errno("fork (async) failed");
1190                 goto error;
1191         }
1192         if (!async->pid) {
1193                 if (need_in)
1194                         close(fdin[1]);
1195                 if (need_out)
1196                         close(fdout[0]);
1197                 git_atexit_clear();
1198                 process_is_async = 1;
1199                 exit(!!async->proc(proc_in, proc_out, async->data));
1200         }
1201
1202         mark_child_for_cleanup(async->pid, NULL);
1203
1204         if (need_in)
1205                 close(fdin[0]);
1206         else if (async->in)
1207                 close(async->in);
1208
1209         if (need_out)
1210                 close(fdout[1]);
1211         else if (async->out)
1212                 close(async->out);
1213 #else
1214         if (!main_thread_set) {
1215                 /*
1216                  * We assume that the first time that start_async is called
1217                  * it is from the main thread.
1218                  */
1219                 main_thread_set = 1;
1220                 main_thread = pthread_self();
1221                 pthread_key_create(&async_key, NULL);
1222                 pthread_key_create(&async_die_counter, NULL);
1223                 set_die_routine(die_async);
1224                 set_die_is_recursing_routine(async_die_is_recursing);
1225         }
1226
1227         if (proc_in >= 0)
1228                 set_cloexec(proc_in);
1229         if (proc_out >= 0)
1230                 set_cloexec(proc_out);
1231         async->proc_in = proc_in;
1232         async->proc_out = proc_out;
1233         {
1234                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1235                 if (err) {
1236                         error(_("cannot create async thread: %s"), strerror(err));
1237                         goto error;
1238                 }
1239         }
1240 #endif
1241         return 0;
1242
1243 error:
1244         if (need_in)
1245                 close_pair(fdin);
1246         else if (async->in)
1247                 close(async->in);
1248
1249         if (need_out)
1250                 close_pair(fdout);
1251         else if (async->out)
1252                 close(async->out);
1253         return -1;
1254 }
1255
1256 int finish_async(struct async *async)
1257 {
1258 #ifdef NO_PTHREADS
1259         int ret = wait_or_whine(async->pid, "child process", 0);
1260
1261         invalidate_lstat_cache();
1262
1263         return ret;
1264 #else
1265         void *ret = (void *)(intptr_t)(-1);
1266
1267         if (pthread_join(async->tid, &ret))
1268                 error("pthread_join failed");
1269         invalidate_lstat_cache();
1270         return (int)(intptr_t)ret;
1271
1272 #endif
1273 }
1274
1275 int async_with_fork(void)
1276 {
1277 #ifdef NO_PTHREADS
1278         return 1;
1279 #else
1280         return 0;
1281 #endif
1282 }
1283
1284 struct io_pump {
1285         /* initialized by caller */
1286         int fd;
1287         int type; /* POLLOUT or POLLIN */
1288         union {
1289                 struct {
1290                         const char *buf;
1291                         size_t len;
1292                 } out;
1293                 struct {
1294                         struct strbuf *buf;
1295                         size_t hint;
1296                 } in;
1297         } u;
1298
1299         /* returned by pump_io */
1300         int error; /* 0 for success, otherwise errno */
1301
1302         /* internal use */
1303         struct pollfd *pfd;
1304 };
1305
1306 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1307 {
1308         int pollsize = 0;
1309         int i;
1310
1311         for (i = 0; i < nr; i++) {
1312                 struct io_pump *io = &slots[i];
1313                 if (io->fd < 0)
1314                         continue;
1315                 pfd[pollsize].fd = io->fd;
1316                 pfd[pollsize].events = io->type;
1317                 io->pfd = &pfd[pollsize++];
1318         }
1319
1320         if (!pollsize)
1321                 return 0;
1322
1323         if (poll(pfd, pollsize, -1) < 0) {
1324                 if (errno == EINTR)
1325                         return 1;
1326                 die_errno("poll failed");
1327         }
1328
1329         for (i = 0; i < nr; i++) {
1330                 struct io_pump *io = &slots[i];
1331
1332                 if (io->fd < 0)
1333                         continue;
1334
1335                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1336                         continue;
1337
1338                 if (io->type == POLLOUT) {
1339                         ssize_t len;
1340
1341                         /*
1342                          * Don't use xwrite() here. It loops forever on EAGAIN,
1343                          * and we're in our own poll() loop here.
1344                          *
1345                          * Note that we lose xwrite()'s handling of MAX_IO_SIZE
1346                          * and EINTR, so we have to implement those ourselves.
1347                          */
1348                         len = write(io->fd, io->u.out.buf,
1349                                     io->u.out.len <= MAX_IO_SIZE ?
1350                                     io->u.out.len : MAX_IO_SIZE);
1351                         if (len < 0) {
1352                                 if (errno != EINTR && errno != EAGAIN &&
1353                                     errno != ENOSPC) {
1354                                         io->error = errno;
1355                                         close(io->fd);
1356                                         io->fd = -1;
1357                                 }
1358                         } else {
1359                                 io->u.out.buf += len;
1360                                 io->u.out.len -= len;
1361                                 if (!io->u.out.len) {
1362                                         close(io->fd);
1363                                         io->fd = -1;
1364                                 }
1365                         }
1366                 }
1367
1368                 if (io->type == POLLIN) {
1369                         ssize_t len = strbuf_read_once(io->u.in.buf,
1370                                                        io->fd, io->u.in.hint);
1371                         if (len < 0)
1372                                 io->error = errno;
1373                         if (len <= 0) {
1374                                 close(io->fd);
1375                                 io->fd = -1;
1376                         }
1377                 }
1378         }
1379
1380         return 1;
1381 }
1382
1383 static int pump_io(struct io_pump *slots, int nr)
1384 {
1385         struct pollfd *pfd;
1386         int i;
1387
1388         for (i = 0; i < nr; i++)
1389                 slots[i].error = 0;
1390
1391         ALLOC_ARRAY(pfd, nr);
1392         while (pump_io_round(slots, nr, pfd))
1393                 ; /* nothing */
1394         free(pfd);
1395
1396         /* There may be multiple errno values, so just pick the first. */
1397         for (i = 0; i < nr; i++) {
1398                 if (slots[i].error) {
1399                         errno = slots[i].error;
1400                         return -1;
1401                 }
1402         }
1403         return 0;
1404 }
1405
1406
1407 int pipe_command(struct child_process *cmd,
1408                  const char *in, size_t in_len,
1409                  struct strbuf *out, size_t out_hint,
1410                  struct strbuf *err, size_t err_hint)
1411 {
1412         struct io_pump io[3];
1413         int nr = 0;
1414
1415         if (in)
1416                 cmd->in = -1;
1417         if (out)
1418                 cmd->out = -1;
1419         if (err)
1420                 cmd->err = -1;
1421
1422         if (start_command(cmd) < 0)
1423                 return -1;
1424
1425         if (in) {
1426                 if (enable_pipe_nonblock(cmd->in) < 0) {
1427                         error_errno("unable to make pipe non-blocking");
1428                         close(cmd->in);
1429                         if (out)
1430                                 close(cmd->out);
1431                         if (err)
1432                                 close(cmd->err);
1433                         return -1;
1434                 }
1435                 io[nr].fd = cmd->in;
1436                 io[nr].type = POLLOUT;
1437                 io[nr].u.out.buf = in;
1438                 io[nr].u.out.len = in_len;
1439                 nr++;
1440         }
1441         if (out) {
1442                 io[nr].fd = cmd->out;
1443                 io[nr].type = POLLIN;
1444                 io[nr].u.in.buf = out;
1445                 io[nr].u.in.hint = out_hint;
1446                 nr++;
1447         }
1448         if (err) {
1449                 io[nr].fd = cmd->err;
1450                 io[nr].type = POLLIN;
1451                 io[nr].u.in.buf = err;
1452                 io[nr].u.in.hint = err_hint;
1453                 nr++;
1454         }
1455
1456         if (pump_io(io, nr) < 0) {
1457                 finish_command(cmd); /* throw away exit code */
1458                 return -1;
1459         }
1460
1461         return finish_command(cmd);
1462 }
1463
1464 enum child_state {
1465         GIT_CP_FREE,
1466         GIT_CP_WORKING,
1467         GIT_CP_WAIT_CLEANUP,
1468 };
1469
1470 struct parallel_processes {
1471         size_t nr_processes;
1472
1473         struct {
1474                 enum child_state state;
1475                 struct child_process process;
1476                 struct strbuf err;
1477                 void *data;
1478         } *children;
1479         /*
1480          * The struct pollfd is logically part of *children,
1481          * but the system call expects it as its own array.
1482          */
1483         struct pollfd *pfd;
1484
1485         unsigned shutdown : 1;
1486
1487         size_t output_owner;
1488         struct strbuf buffered_output; /* of finished children */
1489 };
1490
1491 struct parallel_processes_for_signal {
1492         const struct run_process_parallel_opts *opts;
1493         const struct parallel_processes *pp;
1494 };
1495
1496 static void kill_children(const struct parallel_processes *pp,
1497                           const struct run_process_parallel_opts *opts,
1498                           int signo)
1499 {
1500         for (size_t i = 0; i < opts->processes; i++)
1501                 if (pp->children[i].state == GIT_CP_WORKING)
1502                         kill(pp->children[i].process.pid, signo);
1503 }
1504
1505 static void kill_children_signal(const struct parallel_processes_for_signal *pp_sig,
1506                                  int signo)
1507 {
1508         kill_children(pp_sig->pp, pp_sig->opts, signo);
1509 }
1510
1511 static struct parallel_processes_for_signal *pp_for_signal;
1512
1513 static void handle_children_on_signal(int signo)
1514 {
1515         kill_children_signal(pp_for_signal, signo);
1516         sigchain_pop(signo);
1517         raise(signo);
1518 }
1519
1520 static void pp_init(struct parallel_processes *pp,
1521                     const struct run_process_parallel_opts *opts,
1522                     struct parallel_processes_for_signal *pp_sig)
1523 {
1524         const size_t n = opts->processes;
1525
1526         if (!n)
1527                 BUG("you must provide a non-zero number of processes!");
1528
1529         trace_printf("run_processes_parallel: preparing to run up to %"PRIuMAX" tasks",
1530                      (uintmax_t)n);
1531
1532         if (!opts->get_next_task)
1533                 BUG("you need to specify a get_next_task function");
1534
1535         CALLOC_ARRAY(pp->children, n);
1536         if (!opts->ungroup)
1537                 CALLOC_ARRAY(pp->pfd, n);
1538
1539         for (size_t i = 0; i < n; i++) {
1540                 strbuf_init(&pp->children[i].err, 0);
1541                 child_process_init(&pp->children[i].process);
1542                 if (pp->pfd) {
1543                         pp->pfd[i].events = POLLIN | POLLHUP;
1544                         pp->pfd[i].fd = -1;
1545                 }
1546         }
1547
1548         pp_sig->pp = pp;
1549         pp_sig->opts = opts;
1550         pp_for_signal = pp_sig;
1551         sigchain_push_common(handle_children_on_signal);
1552 }
1553
1554 static void pp_cleanup(struct parallel_processes *pp,
1555                        const struct run_process_parallel_opts *opts)
1556 {
1557         trace_printf("run_processes_parallel: done");
1558         for (size_t i = 0; i < opts->processes; i++) {
1559                 strbuf_release(&pp->children[i].err);
1560                 child_process_clear(&pp->children[i].process);
1561         }
1562
1563         free(pp->children);
1564         free(pp->pfd);
1565
1566         /*
1567          * When get_next_task added messages to the buffer in its last
1568          * iteration, the buffered output is non empty.
1569          */
1570         strbuf_write(&pp->buffered_output, stderr);
1571         strbuf_release(&pp->buffered_output);
1572
1573         sigchain_pop_common();
1574 }
1575
1576 /* returns
1577  *  0 if a new task was started.
1578  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1579  *    problem with starting a new command)
1580  * <0 no new job was started, user wishes to shutdown early. Use negative code
1581  *    to signal the children.
1582  */
1583 static int pp_start_one(struct parallel_processes *pp,
1584                         const struct run_process_parallel_opts *opts)
1585 {
1586         size_t i;
1587         int code;
1588
1589         for (i = 0; i < opts->processes; i++)
1590                 if (pp->children[i].state == GIT_CP_FREE)
1591                         break;
1592         if (i == opts->processes)
1593                 BUG("bookkeeping is hard");
1594
1595         /*
1596          * By default, do not inherit stdin from the parent process - otherwise,
1597          * all children would share stdin! Users may overwrite this to provide
1598          * something to the child's stdin by having their 'get_next_task'
1599          * callback assign 0 to .no_stdin and an appropriate integer to .in.
1600          */
1601         pp->children[i].process.no_stdin = 1;
1602
1603         code = opts->get_next_task(&pp->children[i].process,
1604                                    opts->ungroup ? NULL : &pp->children[i].err,
1605                                    opts->data,
1606                                    &pp->children[i].data);
1607         if (!code) {
1608                 if (!opts->ungroup) {
1609                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1610                         strbuf_reset(&pp->children[i].err);
1611                 }
1612                 return 1;
1613         }
1614         if (!opts->ungroup) {
1615                 pp->children[i].process.err = -1;
1616                 pp->children[i].process.stdout_to_stderr = 1;
1617         }
1618
1619         if (start_command(&pp->children[i].process)) {
1620                 if (opts->start_failure)
1621                         code = opts->start_failure(opts->ungroup ? NULL :
1622                                                    &pp->children[i].err,
1623                                                    opts->data,
1624                                                    pp->children[i].data);
1625                 else
1626                         code = 0;
1627
1628                 if (!opts->ungroup) {
1629                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1630                         strbuf_reset(&pp->children[i].err);
1631                 }
1632                 if (code)
1633                         pp->shutdown = 1;
1634                 return code;
1635         }
1636
1637         pp->nr_processes++;
1638         pp->children[i].state = GIT_CP_WORKING;
1639         if (pp->pfd)
1640                 pp->pfd[i].fd = pp->children[i].process.err;
1641         return 0;
1642 }
1643
1644 static void pp_buffer_stderr(struct parallel_processes *pp,
1645                              const struct run_process_parallel_opts *opts,
1646                              int output_timeout)
1647 {
1648         while (poll(pp->pfd, opts->processes, output_timeout) < 0) {
1649                 if (errno == EINTR)
1650                         continue;
1651                 pp_cleanup(pp, opts);
1652                 die_errno("poll");
1653         }
1654
1655         /* Buffer output from all pipes. */
1656         for (size_t i = 0; i < opts->processes; i++) {
1657                 if (pp->children[i].state == GIT_CP_WORKING &&
1658                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1659                         int n = strbuf_read_once(&pp->children[i].err,
1660                                                  pp->children[i].process.err, 0);
1661                         if (n == 0) {
1662                                 close(pp->children[i].process.err);
1663                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1664                         } else if (n < 0)
1665                                 if (errno != EAGAIN)
1666                                         die_errno("read");
1667                 }
1668         }
1669 }
1670
1671 static void pp_output(const struct parallel_processes *pp)
1672 {
1673         size_t i = pp->output_owner;
1674
1675         if (pp->children[i].state == GIT_CP_WORKING &&
1676             pp->children[i].err.len) {
1677                 strbuf_write(&pp->children[i].err, stderr);
1678                 strbuf_reset(&pp->children[i].err);
1679         }
1680 }
1681
1682 static int pp_collect_finished(struct parallel_processes *pp,
1683                                const struct run_process_parallel_opts *opts)
1684 {
1685         int code;
1686         size_t i;
1687         int result = 0;
1688
1689         while (pp->nr_processes > 0) {
1690                 for (i = 0; i < opts->processes; i++)
1691                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1692                                 break;
1693                 if (i == opts->processes)
1694                         break;
1695
1696                 code = finish_command(&pp->children[i].process);
1697
1698                 if (opts->task_finished)
1699                         code = opts->task_finished(code, opts->ungroup ? NULL :
1700                                                    &pp->children[i].err, opts->data,
1701                                                    pp->children[i].data);
1702                 else
1703                         code = 0;
1704
1705                 if (code)
1706                         result = code;
1707                 if (code < 0)
1708                         break;
1709
1710                 pp->nr_processes--;
1711                 pp->children[i].state = GIT_CP_FREE;
1712                 if (pp->pfd)
1713                         pp->pfd[i].fd = -1;
1714                 child_process_init(&pp->children[i].process);
1715
1716                 if (opts->ungroup) {
1717                         ; /* no strbuf_*() work to do here */
1718                 } else if (i != pp->output_owner) {
1719                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1720                         strbuf_reset(&pp->children[i].err);
1721                 } else {
1722                         const size_t n = opts->processes;
1723
1724                         strbuf_write(&pp->children[i].err, stderr);
1725                         strbuf_reset(&pp->children[i].err);
1726
1727                         /* Output all other finished child processes */
1728                         strbuf_write(&pp->buffered_output, stderr);
1729                         strbuf_reset(&pp->buffered_output);
1730
1731                         /*
1732                          * Pick next process to output live.
1733                          * NEEDSWORK:
1734                          * For now we pick it randomly by doing a round
1735                          * robin. Later we may want to pick the one with
1736                          * the most output or the longest or shortest
1737                          * running process time.
1738                          */
1739                         for (i = 0; i < n; i++)
1740                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1741                                         break;
1742                         pp->output_owner = (pp->output_owner + i) % n;
1743                 }
1744         }
1745         return result;
1746 }
1747
1748 void run_processes_parallel(const struct run_process_parallel_opts *opts)
1749 {
1750         int i, code;
1751         int output_timeout = 100;
1752         int spawn_cap = 4;
1753         struct parallel_processes_for_signal pp_sig;
1754         struct parallel_processes pp = {
1755                 .buffered_output = STRBUF_INIT,
1756         };
1757         /* options */
1758         const char *tr2_category = opts->tr2_category;
1759         const char *tr2_label = opts->tr2_label;
1760         const int do_trace2 = tr2_category && tr2_label;
1761
1762         if (do_trace2)
1763                 trace2_region_enter_printf(tr2_category, tr2_label, NULL,
1764                                            "max:%d", opts->processes);
1765
1766         pp_init(&pp, opts, &pp_sig);
1767         while (1) {
1768                 for (i = 0;
1769                     i < spawn_cap && !pp.shutdown &&
1770                     pp.nr_processes < opts->processes;
1771                     i++) {
1772                         code = pp_start_one(&pp, opts);
1773                         if (!code)
1774                                 continue;
1775                         if (code < 0) {
1776                                 pp.shutdown = 1;
1777                                 kill_children(&pp, opts, -code);
1778                         }
1779                         break;
1780                 }
1781                 if (!pp.nr_processes)
1782                         break;
1783                 if (opts->ungroup) {
1784                         for (size_t i = 0; i < opts->processes; i++)
1785                                 pp.children[i].state = GIT_CP_WAIT_CLEANUP;
1786                 } else {
1787                         pp_buffer_stderr(&pp, opts, output_timeout);
1788                         pp_output(&pp);
1789                 }
1790                 code = pp_collect_finished(&pp, opts);
1791                 if (code) {
1792                         pp.shutdown = 1;
1793                         if (code < 0)
1794                                 kill_children(&pp, opts,-code);
1795                 }
1796         }
1797
1798         pp_cleanup(&pp, opts);
1799
1800         if (do_trace2)
1801                 trace2_region_leave(tr2_category, tr2_label, NULL);
1802 }
1803
1804 int run_auto_maintenance(int quiet)
1805 {
1806         int enabled;
1807         struct child_process maint = CHILD_PROCESS_INIT;
1808
1809         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1810             !enabled)
1811                 return 0;
1812
1813         maint.git_cmd = 1;
1814         maint.close_object_store = 1;
1815         strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
1816         strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
1817
1818         return run_command(&maint);
1819 }
1820
1821 void prepare_other_repo_env(struct strvec *env, const char *new_git_dir)
1822 {
1823         const char * const *var;
1824
1825         for (var = local_repo_env; *var; var++) {
1826                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1827                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1828                         strvec_push(env, *var);
1829         }
1830         strvec_pushf(env, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1831 }
1832
1833 enum start_bg_result start_bg_command(struct child_process *cmd,
1834                                       start_bg_wait_cb *wait_cb,
1835                                       void *cb_data,
1836                                       unsigned int timeout_sec)
1837 {
1838         enum start_bg_result sbgr = SBGR_ERROR;
1839         int ret;
1840         int wait_status;
1841         pid_t pid_seen;
1842         time_t time_limit;
1843
1844         /*
1845          * We do not allow clean-on-exit because the child process
1846          * should persist in the background and possibly/probably
1847          * after this process exits.  So we don't want to kill the
1848          * child during our atexit routine.
1849          */
1850         if (cmd->clean_on_exit)
1851                 BUG("start_bg_command() does not allow non-zero clean_on_exit");
1852
1853         if (!cmd->trace2_child_class)
1854                 cmd->trace2_child_class = "background";
1855
1856         ret = start_command(cmd);
1857         if (ret) {
1858                 /*
1859                  * We assume that if `start_command()` fails, we
1860                  * either get a complete `trace2_child_start() /
1861                  * trace2_child_exit()` pair or it fails before the
1862                  * `trace2_child_start()` is emitted, so we do not
1863                  * need to worry about it here.
1864                  *
1865                  * We also assume that `start_command()` does not add
1866                  * us to the cleanup list.  And that it calls
1867                  * `child_process_clear()`.
1868                  */
1869                 sbgr = SBGR_ERROR;
1870                 goto done;
1871         }
1872
1873         time(&time_limit);
1874         time_limit += timeout_sec;
1875
1876 wait:
1877         pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
1878
1879         if (!pid_seen) {
1880                 /*
1881                  * The child is currently running.  Ask the callback
1882                  * if the child is ready to do work or whether we
1883                  * should keep waiting for it to boot up.
1884                  */
1885                 ret = (*wait_cb)(cmd, cb_data);
1886                 if (!ret) {
1887                         /*
1888                          * The child is running and "ready".
1889                          */
1890                         trace2_child_ready(cmd, "ready");
1891                         sbgr = SBGR_READY;
1892                         goto done;
1893                 } else if (ret > 0) {
1894                         /*
1895                          * The callback said to give it more time to boot up
1896                          * (subject to our timeout limit).
1897                          */
1898                         time_t now;
1899
1900                         time(&now);
1901                         if (now < time_limit)
1902                                 goto wait;
1903
1904                         /*
1905                          * Our timeout has expired.  We don't try to
1906                          * kill the child, but rather let it continue
1907                          * (hopefully) trying to startup.
1908                          */
1909                         trace2_child_ready(cmd, "timeout");
1910                         sbgr = SBGR_TIMEOUT;
1911                         goto done;
1912                 } else {
1913                         /*
1914                          * The cb gave up on this child.  It is still running,
1915                          * but our cb got an error trying to probe it.
1916                          */
1917                         trace2_child_ready(cmd, "error");
1918                         sbgr = SBGR_CB_ERROR;
1919                         goto done;
1920                 }
1921         }
1922
1923         else if (pid_seen == cmd->pid) {
1924                 int child_code = -1;
1925
1926                 /*
1927                  * The child started, but exited or was terminated
1928                  * before becoming "ready".
1929                  *
1930                  * We try to match the behavior of `wait_or_whine()`
1931                  * WRT the handling of WIFSIGNALED() and WIFEXITED()
1932                  * and convert the child's status to a return code for
1933                  * tracing purposes and emit the `trace2_child_exit()`
1934                  * event.
1935                  *
1936                  * We do not want the wait_or_whine() error message
1937                  * because we will be called by client-side library
1938                  * routines.
1939                  */
1940                 if (WIFEXITED(wait_status))
1941                         child_code = WEXITSTATUS(wait_status);
1942                 else if (WIFSIGNALED(wait_status))
1943                         child_code = WTERMSIG(wait_status) + 128;
1944                 trace2_child_exit(cmd, child_code);
1945
1946                 sbgr = SBGR_DIED;
1947                 goto done;
1948         }
1949
1950         else if (pid_seen < 0 && errno == EINTR)
1951                 goto wait;
1952
1953         trace2_child_exit(cmd, -1);
1954         sbgr = SBGR_ERROR;
1955
1956 done:
1957         child_process_clear(cmd);
1958         invalidate_lstat_cache();
1959         return sbgr;
1960 }