run-command.c

   1 #define USE_THE_REPOSITORY_VARIABLE
   2 #define DISABLE_SIGN_COMPARE_WARNINGS
   3
   4 #include "git-compat-util.h"
   5 #include "run-command.h"
   6 #include "environment.h"
   7 #include "exec-cmd.h"
   8 #include "gettext.h"
   9 #include "sigchain.h"
  10 #include "strvec.h"
  11 #include "symlinks.h"
  12 #include "thread-utils.h"
  13 #include "strbuf.h"
  14 #include "string-list.h"
  15 #include "trace.h"
  16 #include "trace2.h"
  17 #include "quote.h"
  18 #include "config.h"
  19 #include "packfile.h"
  20 #include "compat/nonblock.h"
  21
  22 void child_process_init(struct child_process *child)
  23 {
  24         struct child_process blank = CHILD_PROCESS_INIT;
  25         memcpy(child, &blank, sizeof(*child));
  26 }
  27
  28 void child_process_clear(struct child_process *child)
  29 {
  30         strvec_clear(&child->args);
  31         strvec_clear(&child->env);
  32 }
  33
  34 struct child_to_clean {
  35         pid_t pid;
  36         struct child_process *process;
  37         struct child_to_clean *next;
  38 };
  39 static struct child_to_clean *children_to_clean;
  40 static int installed_child_cleanup_handler;
  41
  42 static void cleanup_children(int sig, int in_signal)
  43 {
  44         struct child_to_clean *children_to_wait_for = NULL;
  45
  46         while (children_to_clean) {
  47                 struct child_to_clean *p = children_to_clean;
  48                 children_to_clean = p->next;
  49
  50                 if (p->process && !in_signal) {
  51                         struct child_process *process = p->process;
  52                         if (process->clean_on_exit_handler) {
  53                                 trace_printf(
  54                                         "trace: run_command: running exit handler for pid %"
  55                                         PRIuMAX, (uintmax_t)p->pid
  56                                 );
  57                                 process->clean_on_exit_handler(process);
  58                         }
  59                 }
  60
  61                 kill(p->pid, sig);
  62
  63                 if (p->process && p->process->wait_after_clean) {
  64                         p->next = children_to_wait_for;
  65                         children_to_wait_for = p;
  66                 } else {
  67                         if (!in_signal)
  68                                 free(p);
  69                 }
  70         }
  71
  72         while (children_to_wait_for) {
  73                 struct child_to_clean *p = children_to_wait_for;
  74                 children_to_wait_for = p->next;
  75
  76                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  77                         ; /* spin waiting for process exit or error */
  78
  79                 if (!in_signal)
  80                         free(p);
  81         }
  82 }
  83
  84 static void cleanup_children_on_signal(int sig)
  85 {
  86         cleanup_children(sig, 1);
  87         sigchain_pop(sig);
  88         raise(sig);
  89 }
  90
  91 static void cleanup_children_on_exit(void)
  92 {
  93         cleanup_children(SIGTERM, 0);
  94 }
  95
  96 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  97 {
  98         struct child_to_clean *p = xmalloc(sizeof(*p));
  99         p->pid = pid;
 100         p->process = process;
 101         p->next = children_to_clean;
 102         children_to_clean = p;
 103
 104         if (!installed_child_cleanup_handler) {
 105                 atexit(cleanup_children_on_exit);
 106                 sigchain_push_common(cleanup_children_on_signal);
 107                 installed_child_cleanup_handler = 1;
 108         }
 109 }
 110
 111 static void clear_child_for_cleanup(pid_t pid)
 112 {
 113         struct child_to_clean **pp;
 114
 115         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 116                 struct child_to_clean *clean_me = *pp;
 117
 118                 if (clean_me->pid == pid) {
 119                         *pp = clean_me->next;
 120                         free(clean_me);
 121                         return;
 122                 }
 123         }
 124 }
 125
 126 static inline void close_pair(int fd[2])
 127 {
 128         close(fd[0]);
 129         close(fd[1]);
 130 }
 131
 132 int is_executable(const char *name)
 133 {
 134         struct stat st;
 135
 136         if (stat(name, &st) || /* stat, not lstat */
 137             !S_ISREG(st.st_mode))
 138                 return 0;
 139
 140 #if defined(GIT_WINDOWS_NATIVE)
 141         /*
 142          * On Windows there is no executable bit. The file extension
 143          * indicates whether it can be run as an executable, and Git
 144          * has special-handling to detect scripts and launch them
 145          * through the indicated script interpreter. We test for the
 146          * file extension first because virus scanners may make
 147          * it quite expensive to open many files.
 148          */
 149         if (ends_with(name, ".exe"))
 150                 return S_IXUSR;
 151
 152 {
 153         /*
 154          * Now that we know it does not have an executable extension,
 155          * peek into the file instead.
 156          */
 157         char buf[3] = { 0 };
 158         int n;
 159         int fd = open(name, O_RDONLY);
 160         st.st_mode &= ~S_IXUSR;
 161         if (fd >= 0) {
 162                 n = read(fd, buf, 2);
 163                 if (n == 2)
 164                         /* look for a she-bang */
 165                         if (!strcmp(buf, "#!"))
 166                                 st.st_mode |= S_IXUSR;
 167                 close(fd);
 168         }
 169 }
 170 #endif
 171         return st.st_mode & S_IXUSR;
 172 }
 173
 174 #ifndef locate_in_PATH
 175 /*
 176  * Search $PATH for a command.  This emulates the path search that
 177  * execvp would perform, without actually executing the command so it
 178  * can be used before fork() to prepare to run a command using
 179  * execve() or after execvp() to diagnose why it failed.
 180  *
 181  * The caller should ensure that file contains no directory
 182  * separators.
 183  *
 184  * Returns the path to the command, as found in $PATH or NULL if the
 185  * command could not be found.  The caller inherits ownership of the memory
 186  * used to store the resultant path.
 187  *
 188  * This should not be used on Windows, where the $PATH search rules
 189  * are more complicated (e.g., a search for "foo" should find
 190  * "foo.exe").
 191  */
 192 static char *locate_in_PATH(const char *file)
 193 {
 194         const char *p = getenv("PATH");
 195         struct strbuf buf = STRBUF_INIT;
 196
 197         if (!p || !*p)
 198                 return NULL;
 199
 200         while (1) {
 201                 const char *end = strchrnul(p, ':');
 202
 203                 strbuf_reset(&buf);
 204
 205                 /* POSIX specifies an empty entry as the current directory. */
 206                 if (end != p) {
 207                         strbuf_add(&buf, p, end - p);
 208                         strbuf_addch(&buf, '/');
 209                 }
 210                 strbuf_addstr(&buf, file);
 211
 212                 if (is_executable(buf.buf))
 213                         return strbuf_detach(&buf, NULL);
 214
 215                 if (!*end)
 216                         break;
 217                 p = end + 1;
 218         }
 219
 220         strbuf_release(&buf);
 221         return NULL;
 222 }
 223 #endif
 224
 225 int exists_in_PATH(const char *command)
 226 {
 227         char *r = locate_in_PATH(command);
 228         int found = r != NULL;
 229         free(r);
 230         return found;
 231 }
 232
 233 int sane_execvp(const char *file, char * const argv[])
 234 {
 235 #ifndef GIT_WINDOWS_NATIVE
 236         /*
 237          * execvp() doesn't return, so we all we can do is tell trace2
 238          * what we are about to do and let it leave a hint in the log
 239          * (unless of course the execvp() fails).
 240          *
 241          * we skip this for Windows because the compat layer already
 242          * has to emulate the execvp() call anyway.
 243          */
 244         int exec_id = trace2_exec(file, (const char **)argv);
 245 #endif
 246
 247         if (!execvp(file, argv))
 248                 return 0; /* cannot happen ;-) */
 249
 250 #ifndef GIT_WINDOWS_NATIVE
 251         {
 252                 int ec = errno;
 253                 trace2_exec_result(exec_id, ec);
 254                 errno = ec;
 255         }
 256 #endif
 257
 258         /*
 259          * When a command can't be found because one of the directories
 260          * listed in $PATH is unsearchable, execvp reports EACCES, but
 261          * careful usability testing (read: analysis of occasional bug
 262          * reports) reveals that "No such file or directory" is more
 263          * intuitive.
 264          *
 265          * We avoid commands with "/", because execvp will not do $PATH
 266          * lookups in that case.
 267          *
 268          * The reassignment of EACCES to errno looks like a no-op below,
 269          * but we need to protect against exists_in_PATH overwriting errno.
 270          */
 271         if (errno == EACCES && !strchr(file, '/'))
 272                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 273         else if (errno == ENOTDIR && !strchr(file, '/'))
 274                 errno = ENOENT;
 275         return -1;
 276 }
 277
 278 char *git_shell_path(void)
 279 {
 280 #ifndef GIT_WINDOWS_NATIVE
 281         return xstrdup(SHELL_PATH);
 282 #else
 283         char *p = locate_in_PATH("sh");
 284         convert_slashes(p);
 285         return p;
 286 #endif
 287 }
 288
 289 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 290 {
 291         if (!argv[0])
 292                 BUG("shell command is empty");
 293
 294         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 295                 strvec_push_nodup(out, git_shell_path());
 296                 strvec_push(out, "-c");
 297
 298                 /*
 299                  * If we have no extra arguments, we do not even need to
 300                  * bother with the "$@" magic.
 301                  */
 302                 if (!argv[1])
 303                         strvec_push(out, argv[0]);
 304                 else
 305                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 306         }
 307
 308         strvec_pushv(out, argv);
 309         return out->v;
 310 }
 311
 312 #ifndef GIT_WINDOWS_NATIVE
 313 static int child_notifier = -1;
 314
 315 enum child_errcode {
 316         CHILD_ERR_CHDIR,
 317         CHILD_ERR_DUP2,
 318         CHILD_ERR_CLOSE,
 319         CHILD_ERR_SIGPROCMASK,
 320         CHILD_ERR_SILENT,
 321         CHILD_ERR_ERRNO
 322 };
 323
 324 struct child_err {
 325         enum child_errcode err;
 326         int syserr; /* errno */
 327 };
 328
 329 static void child_die(enum child_errcode err)
 330 {
 331         struct child_err buf;
 332
 333         buf.err = err;
 334         buf.syserr = errno;
 335
 336         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 337         xwrite(child_notifier, &buf, sizeof(buf));
 338         _exit(1);
 339 }
 340
 341 static void child_dup2(int fd, int to)
 342 {
 343         if (dup2(fd, to) < 0)
 344                 child_die(CHILD_ERR_DUP2);
 345 }
 346
 347 static void child_close(int fd)
 348 {
 349         if (close(fd))
 350                 child_die(CHILD_ERR_CLOSE);
 351 }
 352
 353 static void child_close_pair(int fd[2])
 354 {
 355         child_close(fd[0]);
 356         child_close(fd[1]);
 357 }
 358
 359 static void child_error_fn(const char *err UNUSED, va_list params UNUSED)
 360 {
 361         const char msg[] = "error() should not be called in child\n";
 362         xwrite(2, msg, sizeof(msg) - 1);
 363 }
 364
 365 static void child_warn_fn(const char *err UNUSED, va_list params UNUSED)
 366 {
 367         const char msg[] = "warn() should not be called in child\n";
 368         xwrite(2, msg, sizeof(msg) - 1);
 369 }
 370
 371 static void NORETURN child_die_fn(const char *err UNUSED, va_list params UNUSED)
 372 {
 373         const char msg[] = "die() should not be called in child\n";
 374         xwrite(2, msg, sizeof(msg) - 1);
 375         _exit(2);
 376 }
 377
 378 /* this runs in the parent process */
 379 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 380 {
 381         static void (*old_errfn)(const char *err, va_list params);
 382         report_fn die_message_routine = get_die_message_routine();
 383
 384         old_errfn = get_error_routine();
 385         set_error_routine(die_message_routine);
 386         errno = cerr->syserr;
 387
 388         switch (cerr->err) {
 389         case CHILD_ERR_CHDIR:
 390                 error_errno("exec '%s': cd to '%s' failed",
 391                             cmd->args.v[0], cmd->dir);
 392                 break;
 393         case CHILD_ERR_DUP2:
 394                 error_errno("dup2() in child failed");
 395                 break;
 396         case CHILD_ERR_CLOSE:
 397                 error_errno("close() in child failed");
 398                 break;
 399         case CHILD_ERR_SIGPROCMASK:
 400                 error_errno("sigprocmask failed restoring signals");
 401                 break;
 402         case CHILD_ERR_SILENT:
 403                 break;
 404         case CHILD_ERR_ERRNO:
 405                 error_errno("cannot exec '%s'", cmd->args.v[0]);
 406                 break;
 407         }
 408         set_error_routine(old_errfn);
 409 }
 410
 411 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 412 {
 413         if (!cmd->args.v[0])
 414                 BUG("command is empty");
 415
 416         /*
 417          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 418          * attempt to interpret the command with 'sh'.
 419          */
 420         strvec_push(out, SHELL_PATH);
 421
 422         if (cmd->git_cmd) {
 423                 prepare_git_cmd(out, cmd->args.v);
 424         } else if (cmd->use_shell) {
 425                 prepare_shell_cmd(out, cmd->args.v);
 426         } else {
 427                 strvec_pushv(out, cmd->args.v);
 428         }
 429
 430         /*
 431          * If there are no dir separator characters in the command then perform
 432          * a path lookup and use the resolved path as the command to exec. If
 433          * there are dir separator characters, we have exec attempt to invoke
 434          * the command directly.
 435          */
 436         if (!has_dir_sep(out->v[1])) {
 437                 char *program = locate_in_PATH(out->v[1]);
 438                 if (program) {
 439                         free((char *)out->v[1]);
 440                         out->v[1] = program;
 441                 } else {
 442                         strvec_clear(out);
 443                         errno = ENOENT;
 444                         return -1;
 445                 }
 446         }
 447
 448         return 0;
 449 }
 450
 451 static char **prep_childenv(const char *const *deltaenv)
 452 {
 453         extern char **environ;
 454         char **childenv;
 455         struct string_list env = STRING_LIST_INIT_DUP;
 456         struct strbuf key = STRBUF_INIT;
 457         const char *const *p;
 458         int i;
 459
 460         /* Construct a sorted string list consisting of the current environ */
 461         for (p = (const char *const *) environ; p && *p; p++) {
 462                 const char *equals = strchr(*p, '=');
 463
 464                 if (equals) {
 465                         strbuf_reset(&key);
 466                         strbuf_add(&key, *p, equals - *p);
 467                         string_list_append(&env, key.buf)->util = (void *) *p;
 468                 } else {
 469                         string_list_append(&env, *p)->util = (void *) *p;
 470                 }
 471         }
 472         string_list_sort(&env);
 473
 474         /* Merge in 'deltaenv' with the current environ */
 475         for (p = deltaenv; p && *p; p++) {
 476                 const char *equals = strchr(*p, '=');
 477
 478                 if (equals) {
 479                         /* ('key=value'), insert or replace entry */
 480                         strbuf_reset(&key);
 481                         strbuf_add(&key, *p, equals - *p);
 482                         string_list_insert(&env, key.buf)->util = (void *) *p;
 483                 } else {
 484                         /* otherwise ('key') remove existing entry */
 485                         string_list_remove(&env, *p, 0);
 486                 }
 487         }
 488
 489         /* Create an array of 'char *' to be used as the childenv */
 490         ALLOC_ARRAY(childenv, env.nr + 1);
 491         for (i = 0; i < env.nr; i++)
 492                 childenv[i] = env.items[i].util;
 493         childenv[env.nr] = NULL;
 494
 495         string_list_clear(&env, 0);
 496         strbuf_release(&key);
 497         return childenv;
 498 }
 499
 500 struct atfork_state {
 501 #ifndef NO_PTHREADS
 502         int cs;
 503 #endif
 504         sigset_t old;
 505 };
 506
 507 #define CHECK_BUG(err, msg) \
 508         do { \
 509                 int e = (err); \
 510                 if (e) \
 511                         BUG("%s: %s", msg, strerror(e)); \
 512         } while(0)
 513
 514 static void atfork_prepare(struct atfork_state *as)
 515 {
 516         sigset_t all;
 517
 518         /*
 519          * POSIX says sigfillset() can fail, but an overly clever
 520          * compiler can see through the header files and decide
 521          * it cannot fail on a particular platform it is compiling for,
 522          * triggering -Wunreachable-code false positive.
 523          */
 524         if (NOT_CONSTANT(sigfillset(&all)))
 525                 die_errno("sigfillset");
 526 #ifdef NO_PTHREADS
 527         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 528                 die_errno("sigprocmask");
 529 #else
 530         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 531                 "blocking all signals");
 532         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 533                 "disabling cancellation");
 534 #endif
 535 }
 536
 537 static void atfork_parent(struct atfork_state *as)
 538 {
 539 #ifdef NO_PTHREADS
 540         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 541                 die_errno("sigprocmask");
 542 #else
 543         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 544                 "re-enabling cancellation");
 545         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 546                 "restoring signal mask");
 547 #endif
 548 }
 549 #endif /* GIT_WINDOWS_NATIVE */
 550
 551 static inline void set_cloexec(int fd)
 552 {
 553         int flags = fcntl(fd, F_GETFD);
 554         if (flags >= 0)
 555                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 556 }
 557
 558 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 559 {
 560         int status, code = -1;
 561         pid_t waiting;
 562         int failed_errno = 0;
 563
 564         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 565                 ;       /* nothing */
 566
 567         if (waiting < 0) {
 568                 failed_errno = errno;
 569                 if (!in_signal)
 570                         error_errno("waitpid for %s failed", argv0);
 571         } else if (waiting != pid) {
 572                 if (!in_signal)
 573                         error("waitpid is confused (%s)", argv0);
 574         } else if (WIFSIGNALED(status)) {
 575                 code = WTERMSIG(status);
 576                 if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 577                         error("%s died of signal %d", argv0, code);
 578                 /*
 579                  * This return value is chosen so that code & 0xff
 580                  * mimics the exit code that a POSIX shell would report for
 581                  * a program that died from this signal.
 582                  */
 583                 code += 128;
 584         } else if (WIFEXITED(status)) {
 585                 code = WEXITSTATUS(status);
 586         } else {
 587                 if (!in_signal)
 588                         error("waitpid is confused (%s)", argv0);
 589         }
 590
 591         if (!in_signal)
 592                 clear_child_for_cleanup(pid);
 593
 594         errno = failed_errno;
 595         return code;
 596 }
 597
 598 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 599 {
 600         struct string_list envs = STRING_LIST_INIT_DUP;
 601         const char *const *e;
 602         int i;
 603         int printed_unset = 0;
 604
 605         /* Last one wins, see run-command.c:prep_childenv() for context */
 606         for (e = deltaenv; e && *e; e++) {
 607                 struct strbuf key = STRBUF_INIT;
 608                 char *equals = strchr(*e, '=');
 609
 610                 if (equals) {
 611                         strbuf_add(&key, *e, equals - *e);
 612                         string_list_insert(&envs, key.buf)->util = equals + 1;
 613                 } else {
 614                         string_list_insert(&envs, *e)->util = NULL;
 615                 }
 616                 strbuf_release(&key);
 617         }
 618
 619         /* "unset X Y...;" */
 620         for (i = 0; i < envs.nr; i++) {
 621                 const char *var = envs.items[i].string;
 622                 const char *val = envs.items[i].util;
 623
 624                 if (val || !getenv(var))
 625                         continue;
 626
 627                 if (!printed_unset) {
 628                         strbuf_addstr(dst, " unset");
 629                         printed_unset = 1;
 630                 }
 631                 strbuf_addf(dst, " %s", var);
 632         }
 633         if (printed_unset)
 634                 strbuf_addch(dst, ';');
 635
 636         /* ... followed by "A=B C=D ..." */
 637         for (i = 0; i < envs.nr; i++) {
 638                 const char *var = envs.items[i].string;
 639                 const char *val = envs.items[i].util;
 640                 const char *oldval;
 641
 642                 if (!val)
 643                         continue;
 644
 645                 oldval = getenv(var);
 646                 if (oldval && !strcmp(val, oldval))
 647                         continue;
 648
 649                 strbuf_addf(dst, " %s=", var);
 650                 sq_quote_buf_pretty(dst, val);
 651         }
 652         string_list_clear(&envs, 0);
 653 }
 654
 655 static void trace_run_command(const struct child_process *cp)
 656 {
 657         struct strbuf buf = STRBUF_INIT;
 658
 659         if (!trace_want(&trace_default_key))
 660                 return;
 661
 662         strbuf_addstr(&buf, "trace: run_command:");
 663         if (cp->dir) {
 664                 strbuf_addstr(&buf, " cd ");
 665                 sq_quote_buf_pretty(&buf, cp->dir);
 666                 strbuf_addch(&buf, ';');
 667         }
 668         trace_add_env(&buf, cp->env.v);
 669         if (cp->git_cmd)
 670                 strbuf_addstr(&buf, " git");
 671         sq_quote_argv_pretty(&buf, cp->args.v);
 672
 673         trace_printf("%s", buf.buf);
 674         strbuf_release(&buf);
 675 }
 676
 677 int start_command(struct child_process *cmd)
 678 {
 679         int need_in, need_out, need_err;
 680         int fdin[2], fdout[2], fderr[2];
 681         int failed_errno;
 682         const char *str;
 683
 684         /*
 685          * In case of errors we must keep the promise to close FDs
 686          * that have been passed in via ->in and ->out.
 687          */
 688
 689         need_in = !cmd->no_stdin && cmd->in < 0;
 690         if (need_in) {
 691                 if (pipe(fdin) < 0) {
 692                         failed_errno = errno;
 693                         if (cmd->out > 0)
 694                                 close(cmd->out);
 695                         str = "standard input";
 696                         goto fail_pipe;
 697                 }
 698                 cmd->in = fdin[1];
 699         }
 700
 701         need_out = !cmd->no_stdout
 702                 && !cmd->stdout_to_stderr
 703                 && cmd->out < 0;
 704         if (need_out) {
 705                 if (pipe(fdout) < 0) {
 706                         failed_errno = errno;
 707                         if (need_in)
 708                                 close_pair(fdin);
 709                         else if (cmd->in)
 710                                 close(cmd->in);
 711                         str = "standard output";
 712                         goto fail_pipe;
 713                 }
 714                 cmd->out = fdout[0];
 715         }
 716
 717         need_err = !cmd->no_stderr && cmd->err < 0;
 718         if (need_err) {
 719                 if (pipe(fderr) < 0) {
 720                         failed_errno = errno;
 721                         if (need_in)
 722                                 close_pair(fdin);
 723                         else if (cmd->in)
 724                                 close(cmd->in);
 725                         if (need_out)
 726                                 close_pair(fdout);
 727                         else if (cmd->out)
 728                                 close(cmd->out);
 729                         str = "standard error";
 730 fail_pipe:
 731                         error("cannot create %s pipe for %s: %s",
 732                                 str, cmd->args.v[0], strerror(failed_errno));
 733                         child_process_clear(cmd);
 734                         errno = failed_errno;
 735                         return -1;
 736                 }
 737                 cmd->err = fderr[0];
 738         }
 739
 740         trace2_child_start(cmd);
 741         trace_run_command(cmd);
 742
 743         fflush(NULL);
 744
 745         if (cmd->close_object_store)
 746                 close_object_store(the_repository->objects);
 747
 748 #ifndef GIT_WINDOWS_NATIVE
 749 {
 750         int notify_pipe[2];
 751         int null_fd = -1;
 752         char **childenv;
 753         struct strvec argv = STRVEC_INIT;
 754         struct child_err cerr;
 755         struct atfork_state as;
 756
 757         if (prepare_cmd(&argv, cmd) < 0) {
 758                 failed_errno = errno;
 759                 cmd->pid = -1;
 760                 if (!cmd->silent_exec_failure)
 761                         error_errno("cannot run %s", cmd->args.v[0]);
 762                 goto end_of_spawn;
 763         }
 764
 765         trace_argv_printf(&argv.v[1], "trace: start_command:");
 766
 767         if (pipe(notify_pipe))
 768                 notify_pipe[0] = notify_pipe[1] = -1;
 769
 770         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 771                 null_fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
 772                 set_cloexec(null_fd);
 773         }
 774
 775         childenv = prep_childenv(cmd->env.v);
 776         atfork_prepare(&as);
 777
 778         /*
 779          * NOTE: In order to prevent deadlocking when using threads special
 780          * care should be taken with the function calls made in between the
 781          * fork() and exec() calls.  No calls should be made to functions which
 782          * require acquiring a lock (e.g. malloc) as the lock could have been
 783          * held by another thread at the time of forking, causing the lock to
 784          * never be released in the child process.  This means only
 785          * Async-Signal-Safe functions are permitted in the child.
 786          */
 787         cmd->pid = fork();
 788         failed_errno = errno;
 789         if (!cmd->pid) {
 790                 int sig;
 791                 /*
 792                  * Ensure the default die/error/warn routines do not get
 793                  * called, they can take stdio locks and malloc.
 794                  */
 795                 set_die_routine(child_die_fn);
 796                 set_error_routine(child_error_fn);
 797                 set_warn_routine(child_warn_fn);
 798
 799                 close(notify_pipe[0]);
 800                 set_cloexec(notify_pipe[1]);
 801                 child_notifier = notify_pipe[1];
 802
 803                 if (cmd->no_stdin)
 804                         child_dup2(null_fd, 0);
 805                 else if (need_in) {
 806                         child_dup2(fdin[0], 0);
 807                         child_close_pair(fdin);
 808                 } else if (cmd->in) {
 809                         child_dup2(cmd->in, 0);
 810                         child_close(cmd->in);
 811                 }
 812
 813                 if (cmd->no_stderr)
 814                         child_dup2(null_fd, 2);
 815                 else if (need_err) {
 816                         child_dup2(fderr[1], 2);
 817                         child_close_pair(fderr);
 818                 } else if (cmd->err > 1) {
 819                         child_dup2(cmd->err, 2);
 820                         child_close(cmd->err);
 821                 }
 822
 823                 if (cmd->no_stdout)
 824                         child_dup2(null_fd, 1);
 825                 else if (cmd->stdout_to_stderr)
 826                         child_dup2(2, 1);
 827                 else if (need_out) {
 828                         child_dup2(fdout[1], 1);
 829                         child_close_pair(fdout);
 830                 } else if (cmd->out > 1) {
 831                         child_dup2(cmd->out, 1);
 832                         child_close(cmd->out);
 833                 }
 834
 835                 if (cmd->dir && chdir(cmd->dir))
 836                         child_die(CHILD_ERR_CHDIR);
 837
 838                 /*
 839                  * restore default signal handlers here, in case
 840                  * we catch a signal right before execve below
 841                  */
 842                 for (sig = 1; sig < NSIG; sig++) {
 843                         /* ignored signals get reset to SIG_DFL on execve */
 844                         if (signal(sig, SIG_DFL) == SIG_IGN)
 845                                 signal(sig, SIG_IGN);
 846                 }
 847
 848                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 849                         child_die(CHILD_ERR_SIGPROCMASK);
 850
 851                 /*
 852                  * Attempt to exec using the command and arguments starting at
 853                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 854                  * be used in the event exec failed with ENOEXEC at which point
 855                  * we will try to interpret the command using 'sh'.
 856                  */
 857                 execve(argv.v[1], (char *const *) argv.v + 1,
 858                        (char *const *) childenv);
 859                 if (errno == ENOEXEC)
 860                         execve(argv.v[0], (char *const *) argv.v,
 861                                (char *const *) childenv);
 862
 863                 if (cmd->silent_exec_failure && errno == ENOENT)
 864                         child_die(CHILD_ERR_SILENT);
 865                 child_die(CHILD_ERR_ERRNO);
 866         }
 867         atfork_parent(&as);
 868         if (cmd->pid < 0)
 869                 error_errno("cannot fork() for %s", cmd->args.v[0]);
 870         else if (cmd->clean_on_exit)
 871                 mark_child_for_cleanup(cmd->pid, cmd);
 872
 873         /*
 874          * Wait for child's exec. If the exec succeeds (or if fork()
 875          * failed), EOF is seen immediately by the parent. Otherwise, the
 876          * child process sends a child_err struct.
 877          * Note that use of this infrastructure is completely advisory,
 878          * therefore, we keep error checks minimal.
 879          */
 880         close(notify_pipe[1]);
 881         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 882                 /*
 883                  * At this point we know that fork() succeeded, but exec()
 884                  * failed. Errors have been reported to our stderr.
 885                  */
 886                 wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 887                 child_err_spew(cmd, &cerr);
 888                 failed_errno = errno;
 889                 cmd->pid = -1;
 890         }
 891         close(notify_pipe[0]);
 892
 893         if (null_fd >= 0)
 894                 close(null_fd);
 895         strvec_clear(&argv);
 896         free(childenv);
 897 }
 898 end_of_spawn:
 899
 900 #else
 901 {
 902         int fhin = 0, fhout = 1, fherr = 2;
 903         const char **sargv = cmd->args.v;
 904         struct strvec nargv = STRVEC_INIT;
 905
 906         if (cmd->no_stdin)
 907                 fhin = open("/dev/null", O_RDWR);
 908         else if (need_in)
 909                 fhin = dup(fdin[0]);
 910         else if (cmd->in)
 911                 fhin = dup(cmd->in);
 912
 913         if (cmd->no_stderr)
 914                 fherr = open("/dev/null", O_RDWR);
 915         else if (need_err)
 916                 fherr = dup(fderr[1]);
 917         else if (cmd->err > 2)
 918                 fherr = dup(cmd->err);
 919
 920         if (cmd->no_stdout)
 921                 fhout = open("/dev/null", O_RDWR);
 922         else if (cmd->stdout_to_stderr)
 923                 fhout = dup(fherr);
 924         else if (need_out)
 925                 fhout = dup(fdout[1]);
 926         else if (cmd->out > 1)
 927                 fhout = dup(cmd->out);
 928
 929         if (cmd->git_cmd)
 930                 cmd->args.v = prepare_git_cmd(&nargv, sargv);
 931         else if (cmd->use_shell)
 932                 cmd->args.v = prepare_shell_cmd(&nargv, sargv);
 933
 934         trace_argv_printf(cmd->args.v, "trace: start_command:");
 935         cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v,
 936                                   (char**) cmd->env.v,
 937                                   cmd->dir, fhin, fhout, fherr);
 938         failed_errno = errno;
 939         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 940                 error_errno("cannot spawn %s", cmd->args.v[0]);
 941         if (cmd->clean_on_exit && cmd->pid >= 0)
 942                 mark_child_for_cleanup(cmd->pid, cmd);
 943
 944         strvec_clear(&nargv);
 945         cmd->args.v = sargv;
 946         if (fhin != 0)
 947                 close(fhin);
 948         if (fhout != 1)
 949                 close(fhout);
 950         if (fherr != 2)
 951                 close(fherr);
 952 }
 953 #endif
 954
 955         if (cmd->pid < 0) {
 956                 trace2_child_exit(cmd, -1);
 957
 958                 if (need_in)
 959                         close_pair(fdin);
 960                 else if (cmd->in)
 961                         close(cmd->in);
 962                 if (need_out)
 963                         close_pair(fdout);
 964                 else if (cmd->out)
 965                         close(cmd->out);
 966                 if (need_err)
 967                         close_pair(fderr);
 968                 else if (cmd->err)
 969                         close(cmd->err);
 970                 child_process_clear(cmd);
 971                 errno = failed_errno;
 972                 return -1;
 973         }
 974
 975         if (need_in)
 976                 close(fdin[0]);
 977         else if (cmd->in)
 978                 close(cmd->in);
 979
 980         if (need_out)
 981                 close(fdout[1]);
 982         else if (cmd->out)
 983                 close(cmd->out);
 984
 985         if (need_err)
 986                 close(fderr[1]);
 987         else if (cmd->err)
 988                 close(cmd->err);
 989
 990         return 0;
 991 }
 992
 993 int finish_command(struct child_process *cmd)
 994 {
 995         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 996         trace2_child_exit(cmd, ret);
 997         child_process_clear(cmd);
 998         invalidate_lstat_cache();
 999         return ret;
1000 }
1001
1002 int finish_command_in_signal(struct child_process *cmd)
1003 {
1004         int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
1005         if (ret != -1)
1006                 trace2_child_exit(cmd, ret);
1007         return ret;
1008 }
1009
1010
1011 int run_command(struct child_process *cmd)
1012 {
1013         int code;
1014
1015         if (cmd->out < 0 || cmd->err < 0)
1016                 BUG("run_command with a pipe can cause deadlock");
1017
1018         code = start_command(cmd);
1019         if (code)
1020                 return code;
1021         return finish_command(cmd);
1022 }
1023
1024 #ifndef NO_PTHREADS
1025 static pthread_t main_thread;
1026 static int main_thread_set;
1027 static pthread_key_t async_key;
1028 static pthread_key_t async_die_counter;
1029
1030 static void *run_thread(void *data)
1031 {
1032         struct async *async = data;
1033         intptr_t ret;
1034
1035         if (async->isolate_sigpipe) {
1036                 sigset_t mask;
1037                 sigemptyset(&mask);
1038                 sigaddset(&mask, SIGPIPE);
1039                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL)) {
1040                         ret = error("unable to block SIGPIPE in async thread");
1041                         return (void *)ret;
1042                 }
1043         }
1044
1045         pthread_setspecific(async_key, async);
1046         ret = async->proc(async->proc_in, async->proc_out, async->data);
1047         return (void *)ret;
1048 }
1049
1050 static NORETURN void die_async(const char *err, va_list params)
1051 {
1052         report_fn die_message_fn = get_die_message_routine();
1053
1054         die_message_fn(err, params);
1055
1056         if (in_async()) {
1057                 struct async *async = pthread_getspecific(async_key);
1058                 if (async->proc_in >= 0)
1059                         close(async->proc_in);
1060                 if (async->proc_out >= 0)
1061                         close(async->proc_out);
1062                 pthread_exit((void *)128);
1063         }
1064
1065         exit(128);
1066 }
1067
1068 static int async_die_is_recursing(void)
1069 {
1070         void *ret = pthread_getspecific(async_die_counter);
1071         pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
1072         return ret != NULL;
1073 }
1074
1075 int in_async(void)
1076 {
1077         if (!main_thread_set)
1078                 return 0; /* no asyncs started yet */
1079         return !pthread_equal(main_thread, pthread_self());
1080 }
1081
1082 static void NORETURN async_exit(int code)
1083 {
1084         pthread_exit((void *)(intptr_t)code);
1085 }
1086
1087 #else
1088
1089 static struct {
1090         void (**handlers)(void);
1091         size_t nr;
1092         size_t alloc;
1093 } git_atexit_hdlrs;
1094
1095 static int git_atexit_installed;
1096
1097 static void git_atexit_dispatch(void)
1098 {
1099         size_t i;
1100
1101         for (i=git_atexit_hdlrs.nr ; i ; i--)
1102                 git_atexit_hdlrs.handlers[i-1]();
1103 }
1104
1105 static void git_atexit_clear(void)
1106 {
1107         free(git_atexit_hdlrs.handlers);
1108         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1109         git_atexit_installed = 0;
1110 }
1111
1112 #undef atexit
1113 int git_atexit(void (*handler)(void))
1114 {
1115         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1116         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1117         if (!git_atexit_installed) {
1118                 if (atexit(&git_atexit_dispatch))
1119                         return -1;
1120                 git_atexit_installed = 1;
1121         }
1122         return 0;
1123 }
1124 #define atexit git_atexit
1125
1126 static int process_is_async;
1127 int in_async(void)
1128 {
1129         return process_is_async;
1130 }
1131
1132 static void NORETURN async_exit(int code)
1133 {
1134         exit(code);
1135 }
1136
1137 #endif
1138
1139 void check_pipe(int err)
1140 {
1141         if (err == EPIPE) {
1142                 if (in_async())
1143                         async_exit(141);
1144
1145                 signal(SIGPIPE, SIG_DFL);
1146                 raise(SIGPIPE);
1147                 /* Should never happen, but just in case... */
1148                 exit(141);
1149         }
1150 }
1151
1152 int start_async(struct async *async)
1153 {
1154         int need_in, need_out;
1155         int fdin[2], fdout[2];
1156         int proc_in, proc_out;
1157
1158         need_in = async->in < 0;
1159         if (need_in) {
1160                 if (pipe(fdin) < 0) {
1161                         if (async->out > 0)
1162                                 close(async->out);
1163                         return error_errno("cannot create pipe");
1164                 }
1165                 async->in = fdin[1];
1166         }
1167
1168         need_out = async->out < 0;
1169         if (need_out) {
1170                 if (pipe(fdout) < 0) {
1171                         if (need_in)
1172                                 close_pair(fdin);
1173                         else if (async->in)
1174                                 close(async->in);
1175                         return error_errno("cannot create pipe");
1176                 }
1177                 async->out = fdout[0];
1178         }
1179
1180         if (need_in)
1181                 proc_in = fdin[0];
1182         else if (async->in)
1183                 proc_in = async->in;
1184         else
1185                 proc_in = -1;
1186
1187         if (need_out)
1188                 proc_out = fdout[1];
1189         else if (async->out)
1190                 proc_out = async->out;
1191         else
1192                 proc_out = -1;
1193
1194 #ifdef NO_PTHREADS
1195         /* Flush stdio before fork() to avoid cloning buffers */
1196         fflush(NULL);
1197
1198         async->pid = fork();
1199         if (async->pid < 0) {
1200                 error_errno("fork (async) failed");
1201                 goto error;
1202         }
1203         if (!async->pid) {
1204                 if (need_in)
1205                         close(fdin[1]);
1206                 if (need_out)
1207                         close(fdout[0]);
1208                 git_atexit_clear();
1209                 process_is_async = 1;
1210                 exit(!!async->proc(proc_in, proc_out, async->data));
1211         }
1212
1213         mark_child_for_cleanup(async->pid, NULL);
1214
1215         if (need_in)
1216                 close(fdin[0]);
1217         else if (async->in)
1218                 close(async->in);
1219
1220         if (need_out)
1221                 close(fdout[1]);
1222         else if (async->out)
1223                 close(async->out);
1224 #else
1225         if (!main_thread_set) {
1226                 /*
1227                  * We assume that the first time that start_async is called
1228                  * it is from the main thread.
1229                  */
1230                 main_thread_set = 1;
1231                 main_thread = pthread_self();
1232                 pthread_key_create(&async_key, NULL);
1233                 pthread_key_create(&async_die_counter, NULL);
1234                 set_die_routine(die_async);
1235                 set_die_is_recursing_routine(async_die_is_recursing);
1236         }
1237
1238         if (proc_in >= 0)
1239                 set_cloexec(proc_in);
1240         if (proc_out >= 0)
1241                 set_cloexec(proc_out);
1242         async->proc_in = proc_in;
1243         async->proc_out = proc_out;
1244         {
1245                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1246                 if (err) {
1247                         error(_("cannot create async thread: %s"), strerror(err));
1248                         goto error;
1249                 }
1250         }
1251 #endif
1252         return 0;
1253
1254 error:
1255         if (need_in)
1256                 close_pair(fdin);
1257         else if (async->in)
1258                 close(async->in);
1259
1260         if (need_out)
1261                 close_pair(fdout);
1262         else if (async->out)
1263                 close(async->out);
1264         return -1;
1265 }
1266
1267 int finish_async(struct async *async)
1268 {
1269 #ifdef NO_PTHREADS
1270         int ret = wait_or_whine(async->pid, "child process", 0);
1271
1272         invalidate_lstat_cache();
1273
1274         return ret;
1275 #else
1276         void *ret = (void *)(intptr_t)(-1);
1277
1278         if (pthread_join(async->tid, &ret))
1279                 error("pthread_join failed");
1280         invalidate_lstat_cache();
1281         return (int)(intptr_t)ret;
1282
1283 #endif
1284 }
1285
1286 int async_with_fork(void)
1287 {
1288 #ifdef NO_PTHREADS
1289         return 1;
1290 #else
1291         return 0;
1292 #endif
1293 }
1294
1295 struct io_pump {
1296         /* initialized by caller */
1297         int fd;
1298         int type; /* POLLOUT or POLLIN */
1299         union {
1300                 struct {
1301                         const char *buf;
1302                         size_t len;
1303                 } out;
1304                 struct {
1305                         struct strbuf *buf;
1306                         size_t hint;
1307                 } in;
1308         } u;
1309
1310         /* returned by pump_io */
1311         int error; /* 0 for success, otherwise errno */
1312
1313         /* internal use */
1314         struct pollfd *pfd;
1315 };
1316
1317 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1318 {
1319         int pollsize = 0;
1320         int i;
1321
1322         for (i = 0; i < nr; i++) {
1323                 struct io_pump *io = &slots[i];
1324                 if (io->fd < 0)
1325                         continue;
1326                 pfd[pollsize].fd = io->fd;
1327                 pfd[pollsize].events = io->type;
1328                 io->pfd = &pfd[pollsize++];
1329         }
1330
1331         if (!pollsize)
1332                 return 0;
1333
1334         if (poll(pfd, pollsize, -1) < 0) {
1335                 if (errno == EINTR)
1336                         return 1;
1337                 die_errno("poll failed");
1338         }
1339
1340         for (i = 0; i < nr; i++) {
1341                 struct io_pump *io = &slots[i];
1342
1343                 if (io->fd < 0)
1344                         continue;
1345
1346                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1347                         continue;
1348
1349                 if (io->type == POLLOUT) {
1350                         ssize_t len;
1351
1352                         /*
1353                          * Don't use xwrite() here. It loops forever on EAGAIN,
1354                          * and we're in our own poll() loop here.
1355                          *
1356                          * Note that we lose xwrite()'s handling of MAX_IO_SIZE
1357                          * and EINTR, so we have to implement those ourselves.
1358                          */
1359                         len = write(io->fd, io->u.out.buf,
1360                                     io->u.out.len <= MAX_IO_SIZE ?
1361                                     io->u.out.len : MAX_IO_SIZE);
1362                         if (len < 0) {
1363                                 if (errno != EINTR && errno != EAGAIN &&
1364                                     errno != ENOSPC) {
1365                                         io->error = errno;
1366                                         close(io->fd);
1367                                         io->fd = -1;
1368                                 }
1369                         } else {
1370                                 io->u.out.buf += len;
1371                                 io->u.out.len -= len;
1372                                 if (!io->u.out.len) {
1373                                         close(io->fd);
1374                                         io->fd = -1;
1375                                 }
1376                         }
1377                 }
1378
1379                 if (io->type == POLLIN) {
1380                         ssize_t len = strbuf_read_once(io->u.in.buf,
1381                                                        io->fd, io->u.in.hint);
1382                         if (len < 0)
1383                                 io->error = errno;
1384                         if (len <= 0) {
1385                                 close(io->fd);
1386                                 io->fd = -1;
1387                         }
1388                 }
1389         }
1390
1391         return 1;
1392 }
1393
1394 static int pump_io(struct io_pump *slots, int nr)
1395 {
1396         struct pollfd *pfd;
1397         int i;
1398
1399         for (i = 0; i < nr; i++)
1400                 slots[i].error = 0;
1401
1402         ALLOC_ARRAY(pfd, nr);
1403         while (pump_io_round(slots, nr, pfd))
1404                 ; /* nothing */
1405         free(pfd);
1406
1407         /* There may be multiple errno values, so just pick the first. */
1408         for (i = 0; i < nr; i++) {
1409                 if (slots[i].error) {
1410                         errno = slots[i].error;
1411                         return -1;
1412                 }
1413         }
1414         return 0;
1415 }
1416
1417
1418 int pipe_command(struct child_process *cmd,
1419                  const char *in, size_t in_len,
1420                  struct strbuf *out, size_t out_hint,
1421                  struct strbuf *err, size_t err_hint)
1422 {
1423         struct io_pump io[3];
1424         int nr = 0;
1425
1426         if (in)
1427                 cmd->in = -1;
1428         if (out)
1429                 cmd->out = -1;
1430         if (err)
1431                 cmd->err = -1;
1432
1433         if (start_command(cmd) < 0)
1434                 return -1;
1435
1436         if (in) {
1437                 if (enable_pipe_nonblock(cmd->in) < 0) {
1438                         error_errno("unable to make pipe non-blocking");
1439                         close(cmd->in);
1440                         if (out)
1441                                 close(cmd->out);
1442                         if (err)
1443                                 close(cmd->err);
1444                         return -1;
1445                 }
1446                 io[nr].fd = cmd->in;
1447                 io[nr].type = POLLOUT;
1448                 io[nr].u.out.buf = in;
1449                 io[nr].u.out.len = in_len;
1450                 nr++;
1451         }
1452         if (out) {
1453                 io[nr].fd = cmd->out;
1454                 io[nr].type = POLLIN;
1455                 io[nr].u.in.buf = out;
1456                 io[nr].u.in.hint = out_hint;
1457                 nr++;
1458         }
1459         if (err) {
1460                 io[nr].fd = cmd->err;
1461                 io[nr].type = POLLIN;
1462                 io[nr].u.in.buf = err;
1463                 io[nr].u.in.hint = err_hint;
1464                 nr++;
1465         }
1466
1467         if (pump_io(io, nr) < 0) {
1468                 finish_command(cmd); /* throw away exit code */
1469                 return -1;
1470         }
1471
1472         return finish_command(cmd);
1473 }
1474
1475 enum child_state {
1476         GIT_CP_FREE,
1477         GIT_CP_WORKING,
1478         GIT_CP_WAIT_CLEANUP,
1479 };
1480
1481 struct parallel_processes {
1482         size_t nr_processes;
1483
1484         struct {
1485                 enum child_state state;
1486                 struct child_process process;
1487                 struct strbuf err;
1488                 void *data;
1489         } *children;
1490         /*
1491          * The struct pollfd is logically part of *children,
1492          * but the system call expects it as its own array.
1493          */
1494         struct pollfd *pfd;
1495
1496         unsigned shutdown : 1;
1497
1498         size_t output_owner;
1499         struct strbuf buffered_output; /* of finished children */
1500 };
1501
1502 struct parallel_processes_for_signal {
1503         const struct run_process_parallel_opts *opts;
1504         const struct parallel_processes *pp;
1505 };
1506
1507 static void kill_children(const struct parallel_processes *pp,
1508                           const struct run_process_parallel_opts *opts,
1509                           int signo)
1510 {
1511         for (size_t i = 0; i < opts->processes; i++)
1512                 if (pp->children[i].state == GIT_CP_WORKING)
1513                         kill(pp->children[i].process.pid, signo);
1514 }
1515
1516 static void kill_children_signal(const struct parallel_processes_for_signal *pp_sig,
1517                                  int signo)
1518 {
1519         kill_children(pp_sig->pp, pp_sig->opts, signo);
1520 }
1521
1522 static struct parallel_processes_for_signal *pp_for_signal;
1523
1524 static void handle_children_on_signal(int signo)
1525 {
1526         kill_children_signal(pp_for_signal, signo);
1527         sigchain_pop(signo);
1528         raise(signo);
1529 }
1530
1531 static void pp_init(struct parallel_processes *pp,
1532                     const struct run_process_parallel_opts *opts,
1533                     struct parallel_processes_for_signal *pp_sig)
1534 {
1535         const size_t n = opts->processes;
1536
1537         if (!n)
1538                 BUG("you must provide a non-zero number of processes!");
1539
1540         trace_printf("run_processes_parallel: preparing to run up to %"PRIuMAX" tasks",
1541                      (uintmax_t)n);
1542
1543         if (!opts->get_next_task)
1544                 BUG("you need to specify a get_next_task function");
1545
1546         CALLOC_ARRAY(pp->children, n);
1547         if (!opts->ungroup)
1548                 CALLOC_ARRAY(pp->pfd, n);
1549
1550         for (size_t i = 0; i < n; i++) {
1551                 strbuf_init(&pp->children[i].err, 0);
1552                 child_process_init(&pp->children[i].process);
1553                 if (pp->pfd) {
1554                         pp->pfd[i].events = POLLIN | POLLHUP;
1555                         pp->pfd[i].fd = -1;
1556                 }
1557         }
1558
1559         pp_sig->pp = pp;
1560         pp_sig->opts = opts;
1561         pp_for_signal = pp_sig;
1562         sigchain_push_common(handle_children_on_signal);
1563 }
1564
1565 static void pp_cleanup(struct parallel_processes *pp,
1566                        const struct run_process_parallel_opts *opts)
1567 {
1568         trace_printf("run_processes_parallel: done");
1569         for (size_t i = 0; i < opts->processes; i++) {
1570                 strbuf_release(&pp->children[i].err);
1571                 child_process_clear(&pp->children[i].process);
1572         }
1573
1574         free(pp->children);
1575         free(pp->pfd);
1576
1577         /*
1578          * When get_next_task added messages to the buffer in its last
1579          * iteration, the buffered output is non empty.
1580          */
1581         strbuf_write(&pp->buffered_output, stderr);
1582         strbuf_release(&pp->buffered_output);
1583
1584         sigchain_pop_common();
1585 }
1586
1587 /* returns
1588  *  0 if a new task was started.
1589  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1590  *    problem with starting a new command)
1591  * <0 no new job was started, user wishes to shutdown early. Use negative code
1592  *    to signal the children.
1593  */
1594 static int pp_start_one(struct parallel_processes *pp,
1595                         const struct run_process_parallel_opts *opts)
1596 {
1597         size_t i;
1598         int code;
1599
1600         for (i = 0; i < opts->processes; i++)
1601                 if (pp->children[i].state == GIT_CP_FREE)
1602                         break;
1603         if (i == opts->processes)
1604                 BUG("bookkeeping is hard");
1605
1606         /*
1607          * By default, do not inherit stdin from the parent process - otherwise,
1608          * all children would share stdin! Users may overwrite this to provide
1609          * something to the child's stdin by having their 'get_next_task'
1610          * callback assign 0 to .no_stdin and an appropriate integer to .in.
1611          */
1612         pp->children[i].process.no_stdin = 1;
1613
1614         code = opts->get_next_task(&pp->children[i].process,
1615                                    opts->ungroup ? NULL : &pp->children[i].err,
1616                                    opts->data,
1617                                    &pp->children[i].data);
1618         if (!code) {
1619                 if (!opts->ungroup) {
1620                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1621                         strbuf_reset(&pp->children[i].err);
1622                 }
1623                 return 1;
1624         }
1625         if (!opts->ungroup) {
1626                 pp->children[i].process.err = -1;
1627                 pp->children[i].process.stdout_to_stderr = 1;
1628         }
1629
1630         if (start_command(&pp->children[i].process)) {
1631                 if (opts->start_failure)
1632                         code = opts->start_failure(opts->ungroup ? NULL :
1633                                                    &pp->children[i].err,
1634                                                    opts->data,
1635                                                    pp->children[i].data);
1636                 else
1637                         code = 0;
1638
1639                 if (!opts->ungroup) {
1640                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1641                         strbuf_reset(&pp->children[i].err);
1642                 }
1643                 if (code)
1644                         pp->shutdown = 1;
1645                 return code;
1646         }
1647
1648         pp->nr_processes++;
1649         pp->children[i].state = GIT_CP_WORKING;
1650         if (pp->pfd)
1651                 pp->pfd[i].fd = pp->children[i].process.err;
1652         return 0;
1653 }
1654
1655 static void pp_buffer_stderr(struct parallel_processes *pp,
1656                              const struct run_process_parallel_opts *opts,
1657                              int output_timeout)
1658 {
1659         while (poll(pp->pfd, opts->processes, output_timeout) < 0) {
1660                 if (errno == EINTR)
1661                         continue;
1662                 pp_cleanup(pp, opts);
1663                 die_errno("poll");
1664         }
1665
1666         /* Buffer output from all pipes. */
1667         for (size_t i = 0; i < opts->processes; i++) {
1668                 if (pp->children[i].state == GIT_CP_WORKING &&
1669                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1670                         int n = strbuf_read_once(&pp->children[i].err,
1671                                                  pp->children[i].process.err, 0);
1672                         if (n == 0) {
1673                                 close(pp->children[i].process.err);
1674                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1675                         } else if (n < 0)
1676                                 if (errno != EAGAIN)
1677                                         die_errno("read");
1678                 }
1679         }
1680 }
1681
1682 static void pp_output(const struct parallel_processes *pp)
1683 {
1684         size_t i = pp->output_owner;
1685
1686         if (pp->children[i].state == GIT_CP_WORKING &&
1687             pp->children[i].err.len) {
1688                 strbuf_write(&pp->children[i].err, stderr);
1689                 strbuf_reset(&pp->children[i].err);
1690         }
1691 }
1692
1693 static int pp_collect_finished(struct parallel_processes *pp,
1694                                const struct run_process_parallel_opts *opts)
1695 {
1696         int code;
1697         size_t i;
1698         int result = 0;
1699
1700         while (pp->nr_processes > 0) {
1701                 for (i = 0; i < opts->processes; i++)
1702                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1703                                 break;
1704                 if (i == opts->processes)
1705                         break;
1706
1707                 code = finish_command(&pp->children[i].process);
1708
1709                 if (opts->task_finished)
1710                         code = opts->task_finished(code, opts->ungroup ? NULL :
1711                                                    &pp->children[i].err, opts->data,
1712                                                    pp->children[i].data);
1713                 else
1714                         code = 0;
1715
1716                 if (code)
1717                         result = code;
1718                 if (code < 0)
1719                         break;
1720
1721                 pp->nr_processes--;
1722                 pp->children[i].state = GIT_CP_FREE;
1723                 if (pp->pfd)
1724                         pp->pfd[i].fd = -1;
1725                 child_process_init(&pp->children[i].process);
1726
1727                 if (opts->ungroup) {
1728                         ; /* no strbuf_*() work to do here */
1729                 } else if (i != pp->output_owner) {
1730                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1731                         strbuf_reset(&pp->children[i].err);
1732                 } else {
1733                         const size_t n = opts->processes;
1734
1735                         strbuf_write(&pp->children[i].err, stderr);
1736                         strbuf_reset(&pp->children[i].err);
1737
1738                         /* Output all other finished child processes */
1739                         strbuf_write(&pp->buffered_output, stderr);
1740                         strbuf_reset(&pp->buffered_output);
1741
1742                         /*
1743                          * Pick next process to output live.
1744                          * NEEDSWORK:
1745                          * For now we pick it randomly by doing a round
1746                          * robin. Later we may want to pick the one with
1747                          * the most output or the longest or shortest
1748                          * running process time.
1749                          */
1750                         for (i = 0; i < n; i++)
1751                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1752                                         break;
1753                         pp->output_owner = (pp->output_owner + i) % n;
1754                 }
1755         }
1756         return result;
1757 }
1758
1759 void run_processes_parallel(const struct run_process_parallel_opts *opts)
1760 {
1761         int i, code;
1762         int output_timeout = 100;
1763         int spawn_cap = 4;
1764         struct parallel_processes_for_signal pp_sig;
1765         struct parallel_processes pp = {
1766                 .buffered_output = STRBUF_INIT,
1767         };
1768         /* options */
1769         const char *tr2_category = opts->tr2_category;
1770         const char *tr2_label = opts->tr2_label;
1771         const int do_trace2 = tr2_category && tr2_label;
1772
1773         if (do_trace2)
1774                 trace2_region_enter_printf(tr2_category, tr2_label, NULL,
1775                                            "max:%"PRIuMAX,
1776                                            (uintmax_t)opts->processes);
1777
1778         pp_init(&pp, opts, &pp_sig);
1779         while (1) {
1780                 for (i = 0;
1781                     i < spawn_cap && !pp.shutdown &&
1782                     pp.nr_processes < opts->processes;
1783                     i++) {
1784                         code = pp_start_one(&pp, opts);
1785                         if (!code)
1786                                 continue;
1787                         if (code < 0) {
1788                                 pp.shutdown = 1;
1789                                 kill_children(&pp, opts, -code);
1790                         }
1791                         break;
1792                 }
1793                 if (!pp.nr_processes)
1794                         break;
1795                 if (opts->ungroup) {
1796                         for (size_t i = 0; i < opts->processes; i++)
1797                                 pp.children[i].state = GIT_CP_WAIT_CLEANUP;
1798                 } else {
1799                         pp_buffer_stderr(&pp, opts, output_timeout);
1800                         pp_output(&pp);
1801                 }
1802                 code = pp_collect_finished(&pp, opts);
1803                 if (code) {
1804                         pp.shutdown = 1;
1805                         if (code < 0)
1806                                 kill_children(&pp, opts,-code);
1807                 }
1808         }
1809
1810         pp_cleanup(&pp, opts);
1811
1812         if (do_trace2)
1813                 trace2_region_leave(tr2_category, tr2_label, NULL);
1814 }
1815
1816 int prepare_auto_maintenance(int quiet, struct child_process *maint)
1817 {
1818         int enabled, auto_detach;
1819
1820         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1821             !enabled)
1822                 return 0;
1823
1824         /*
1825          * When `maintenance.autoDetach` isn't set, then we fall back to
1826          * honoring `gc.autoDetach`. This is somewhat weird, but required to
1827          * retain behaviour from when we used to run git-gc(1) here.
1828          */
1829         if (git_config_get_bool("maintenance.autodetach", &auto_detach) &&
1830             git_config_get_bool("gc.autodetach", &auto_detach))
1831                 auto_detach = 1;
1832
1833         maint->git_cmd = 1;
1834         maint->close_object_store = 1;
1835         strvec_pushl(&maint->args, "maintenance", "run", "--auto", NULL);
1836         strvec_push(&maint->args, quiet ? "--quiet" : "--no-quiet");
1837         strvec_push(&maint->args, auto_detach ? "--detach" : "--no-detach");
1838
1839         return 1;
1840 }
1841
1842 int run_auto_maintenance(int quiet)
1843 {
1844         struct child_process maint = CHILD_PROCESS_INIT;
1845         if (!prepare_auto_maintenance(quiet, &maint))
1846                 return 0;
1847         return run_command(&maint);
1848 }
1849
1850 void prepare_other_repo_env(struct strvec *env, const char *new_git_dir)
1851 {
1852         const char * const *var;
1853
1854         for (var = local_repo_env; *var; var++) {
1855                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1856                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1857                         strvec_push(env, *var);
1858         }
1859         strvec_pushf(env, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1860 }
1861
1862 enum start_bg_result start_bg_command(struct child_process *cmd,
1863                                       start_bg_wait_cb *wait_cb,
1864                                       void *cb_data,
1865                                       unsigned int timeout_sec)
1866 {
1867         enum start_bg_result sbgr = SBGR_ERROR;
1868         int ret;
1869         int wait_status;
1870         pid_t pid_seen;
1871         time_t time_limit;
1872
1873         /*
1874          * We do not allow clean-on-exit because the child process
1875          * should persist in the background and possibly/probably
1876          * after this process exits.  So we don't want to kill the
1877          * child during our atexit routine.
1878          */
1879         if (cmd->clean_on_exit)
1880                 BUG("start_bg_command() does not allow non-zero clean_on_exit");
1881
1882         if (!cmd->trace2_child_class)
1883                 cmd->trace2_child_class = "background";
1884
1885         ret = start_command(cmd);
1886         if (ret) {
1887                 /*
1888                  * We assume that if `start_command()` fails, we
1889                  * either get a complete `trace2_child_start() /
1890                  * trace2_child_exit()` pair or it fails before the
1891                  * `trace2_child_start()` is emitted, so we do not
1892                  * need to worry about it here.
1893                  *
1894                  * We also assume that `start_command()` does not add
1895                  * us to the cleanup list.  And that it calls
1896                  * `child_process_clear()`.
1897                  */
1898                 sbgr = SBGR_ERROR;
1899                 goto done;
1900         }
1901
1902         time(&time_limit);
1903         time_limit += timeout_sec;
1904
1905 wait:
1906         pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
1907
1908         if (!pid_seen) {
1909                 /*
1910                  * The child is currently running.  Ask the callback
1911                  * if the child is ready to do work or whether we
1912                  * should keep waiting for it to boot up.
1913                  */
1914                 ret = (*wait_cb)(cmd, cb_data);
1915                 if (!ret) {
1916                         /*
1917                          * The child is running and "ready".
1918                          */
1919                         trace2_child_ready(cmd, "ready");
1920                         sbgr = SBGR_READY;
1921                         goto done;
1922                 } else if (ret > 0) {
1923                         /*
1924                          * The callback said to give it more time to boot up
1925                          * (subject to our timeout limit).
1926                          */
1927                         time_t now;
1928
1929                         time(&now);
1930                         if (now < time_limit)
1931                                 goto wait;
1932
1933                         /*
1934                          * Our timeout has expired.  We don't try to
1935                          * kill the child, but rather let it continue
1936                          * (hopefully) trying to startup.
1937                          */
1938                         trace2_child_ready(cmd, "timeout");
1939                         sbgr = SBGR_TIMEOUT;
1940                         goto done;
1941                 } else {
1942                         /*
1943                          * The cb gave up on this child.  It is still running,
1944                          * but our cb got an error trying to probe it.
1945                          */
1946                         trace2_child_ready(cmd, "error");
1947                         sbgr = SBGR_CB_ERROR;
1948                         goto done;
1949                 }
1950         }
1951
1952         else if (pid_seen == cmd->pid) {
1953                 int child_code = -1;
1954
1955                 /*
1956                  * The child started, but exited or was terminated
1957                  * before becoming "ready".
1958                  *
1959                  * We try to match the behavior of `wait_or_whine()`
1960                  * WRT the handling of WIFSIGNALED() and WIFEXITED()
1961                  * and convert the child's status to a return code for
1962                  * tracing purposes and emit the `trace2_child_exit()`
1963                  * event.
1964                  *
1965                  * We do not want the wait_or_whine() error message
1966                  * because we will be called by client-side library
1967                  * routines.
1968                  */
1969                 if (WIFEXITED(wait_status))
1970                         child_code = WEXITSTATUS(wait_status);
1971                 else if (WIFSIGNALED(wait_status))
1972                         child_code = WTERMSIG(wait_status) + 128;
1973                 trace2_child_exit(cmd, child_code);
1974
1975                 sbgr = SBGR_DIED;
1976                 goto done;
1977         }
1978
1979         else if (pid_seen < 0 && errno == EINTR)
1980                 goto wait;
1981
1982         trace2_child_exit(cmd, -1);
1983         sbgr = SBGR_ERROR;
1984
1985 done:
1986         child_process_clear(cmd);
1987         invalidate_lstat_cache();
1988         return sbgr;
1989 }