run-command.c

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