run-command.c

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