git.oblomov.eu Git - git/blob - run-command.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "exec-cmd.h"
   4 #include "sigchain.h"
   5 #include "strvec.h"
   6 #include "thread-utils.h"
   7 #include "strbuf.h"
   8 #include "string-list.h"
   9 #include "quote.h"
  10 #include "config.h"
  11 #include "hook.h"
  12
  13 void child_process_init(struct child_process *child)
  14 {
  15         memset(child, 0, sizeof(*child));
  16         strvec_init(&child->args);
  17         strvec_init(&child->env_array);
  18 }
  19
  20 void child_process_clear(struct child_process *child)
  21 {
  22         strvec_clear(&child->args);
  23         strvec_clear(&child->env_array);
  24 }
  25
  26 struct child_to_clean {
  27         pid_t pid;
  28         struct child_process *process;
  29         struct child_to_clean *next;
  30 };
  31 static struct child_to_clean *children_to_clean;
  32 static int installed_child_cleanup_handler;
  33
  34 static void cleanup_children(int sig, int in_signal)
  35 {
  36         struct child_to_clean *children_to_wait_for = NULL;
  37
  38         while (children_to_clean) {
  39                 struct child_to_clean *p = children_to_clean;
  40                 children_to_clean = p->next;
  41
  42                 if (p->process && !in_signal) {
  43                         struct child_process *process = p->process;
  44                         if (process->clean_on_exit_handler) {
  45                                 trace_printf(
  46                                         "trace: run_command: running exit handler for pid %"
  47                                         PRIuMAX, (uintmax_t)p->pid
  48                                 );
  49                                 process->clean_on_exit_handler(process);
  50                         }
  51                 }
  52
  53                 kill(p->pid, sig);
  54
  55                 if (p->process && p->process->wait_after_clean) {
  56                         p->next = children_to_wait_for;
  57                         children_to_wait_for = p;
  58                 } else {
  59                         if (!in_signal)
  60                                 free(p);
  61                 }
  62         }
  63
  64         while (children_to_wait_for) {
  65                 struct child_to_clean *p = children_to_wait_for;
  66                 children_to_wait_for = p->next;
  67
  68                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  69                         ; /* spin waiting for process exit or error */
  70
  71                 if (!in_signal)
  72                         free(p);
  73         }
  74 }
  75
  76 static void cleanup_children_on_signal(int sig)
  77 {
  78         cleanup_children(sig, 1);
  79         sigchain_pop(sig);
  80         raise(sig);
  81 }
  82
  83 static void cleanup_children_on_exit(void)
  84 {
  85         cleanup_children(SIGTERM, 0);
  86 }
  87
  88 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  89 {
  90         struct child_to_clean *p = xmalloc(sizeof(*p));
  91         p->pid = pid;
  92         p->process = process;
  93         p->next = children_to_clean;
  94         children_to_clean = p;
  95
  96         if (!installed_child_cleanup_handler) {
  97                 atexit(cleanup_children_on_exit);
  98                 sigchain_push_common(cleanup_children_on_signal);
  99                 installed_child_cleanup_handler = 1;
 100         }
 101 }
 102
 103 static void clear_child_for_cleanup(pid_t pid)
 104 {
 105         struct child_to_clean **pp;
 106
 107         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 108                 struct child_to_clean *clean_me = *pp;
 109
 110                 if (clean_me->pid == pid) {
 111                         *pp = clean_me->next;
 112                         free(clean_me);
 113                         return;
 114                 }
 115         }
 116 }
 117
 118 static inline void close_pair(int fd[2])
 119 {
 120         close(fd[0]);
 121         close(fd[1]);
 122 }
 123
 124 int is_executable(const char *name)
 125 {
 126         struct stat st;
 127
 128         if (stat(name, &st) || /* stat, not lstat */
 129             !S_ISREG(st.st_mode))
 130                 return 0;
 131
 132 #if defined(GIT_WINDOWS_NATIVE)
 133         /*
 134          * On Windows there is no executable bit. The file extension
 135          * indicates whether it can be run as an executable, and Git
 136          * has special-handling to detect scripts and launch them
 137          * through the indicated script interpreter. We test for the
 138          * file extension first because virus scanners may make
 139          * it quite expensive to open many files.
 140          */
 141         if (ends_with(name, ".exe"))
 142                 return S_IXUSR;
 143
 144 {
 145         /*
 146          * Now that we know it does not have an executable extension,
 147          * peek into the file instead.
 148          */
 149         char buf[3] = { 0 };
 150         int n;
 151         int fd = open(name, O_RDONLY);
 152         st.st_mode &= ~S_IXUSR;
 153         if (fd >= 0) {
 154                 n = read(fd, buf, 2);
 155                 if (n == 2)
 156                         /* look for a she-bang */
 157                         if (!strcmp(buf, "#!"))
 158                                 st.st_mode |= S_IXUSR;
 159                 close(fd);
 160         }
 161 }
 162 #endif
 163         return st.st_mode & S_IXUSR;
 164 }
 165
 166 /*
 167  * Search $PATH for a command.  This emulates the path search that
 168  * execvp would perform, without actually executing the command so it
 169  * can be used before fork() to prepare to run a command using
 170  * execve() or after execvp() to diagnose why it failed.
 171  *
 172  * The caller should ensure that file contains no directory
 173  * separators.
 174  *
 175  * Returns the path to the command, as found in $PATH or NULL if the
 176  * command could not be found.  The caller inherits ownership of the memory
 177  * used to store the resultant path.
 178  *
 179  * This should not be used on Windows, where the $PATH search rules
 180  * are more complicated (e.g., a search for "foo" should find
 181  * "foo.exe").
 182  */
 183 static char *locate_in_PATH(const char *file)
 184 {
 185         const char *p = getenv("PATH");
 186         struct strbuf buf = STRBUF_INIT;
 187
 188         if (!p || !*p)
 189                 return NULL;
 190
 191         while (1) {
 192                 const char *end = strchrnul(p, ':');
 193
 194                 strbuf_reset(&buf);
 195
 196                 /* POSIX specifies an empty entry as the current directory. */
 197                 if (end != p) {
 198                         strbuf_add(&buf, p, end - p);
 199                         strbuf_addch(&buf, '/');
 200                 }
 201                 strbuf_addstr(&buf, file);
 202
 203                 if (is_executable(buf.buf))
 204                         return strbuf_detach(&buf, NULL);
 205
 206                 if (!*end)
 207                         break;
 208                 p = end + 1;
 209         }
 210
 211         strbuf_release(&buf);
 212         return NULL;
 213 }
 214
 215 static int exists_in_PATH(const char *file)
 216 {
 217         char *r = locate_in_PATH(file);
 218         int found = r != NULL;
 219         free(r);
 220         return found;
 221 }
 222
 223 int sane_execvp(const char *file, char * const argv[])
 224 {
 225 #ifndef GIT_WINDOWS_NATIVE
 226         /*
 227          * execvp() doesn't return, so we all we can do is tell trace2
 228          * what we are about to do and let it leave a hint in the log
 229          * (unless of course the execvp() fails).
 230          *
 231          * we skip this for Windows because the compat layer already
 232          * has to emulate the execvp() call anyway.
 233          */
 234         int exec_id = trace2_exec(file, (const char **)argv);
 235 #endif
 236
 237         if (!execvp(file, argv))
 238                 return 0; /* cannot happen ;-) */
 239
 240 #ifndef GIT_WINDOWS_NATIVE
 241         {
 242                 int ec = errno;
 243                 trace2_exec_result(exec_id, ec);
 244                 errno = ec;
 245         }
 246 #endif
 247
 248         /*
 249          * When a command can't be found because one of the directories
 250          * listed in $PATH is unsearchable, execvp reports EACCES, but
 251          * careful usability testing (read: analysis of occasional bug
 252          * reports) reveals that "No such file or directory" is more
 253          * intuitive.
 254          *
 255          * We avoid commands with "/", because execvp will not do $PATH
 256          * lookups in that case.
 257          *
 258          * The reassignment of EACCES to errno looks like a no-op below,
 259          * but we need to protect against exists_in_PATH overwriting errno.
 260          */
 261         if (errno == EACCES && !strchr(file, '/'))
 262                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 263         else if (errno == ENOTDIR && !strchr(file, '/'))
 264                 errno = ENOENT;
 265         return -1;
 266 }
 267
 268 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 269 {
 270         if (!argv[0])
 271                 BUG("shell command is empty");
 272
 273         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 274 #ifndef GIT_WINDOWS_NATIVE
 275                 strvec_push(out, SHELL_PATH);
 276 #else
 277                 strvec_push(out, "sh");
 278 #endif
 279                 strvec_push(out, "-c");
 280
 281                 /*
 282                  * If we have no extra arguments, we do not even need to
 283                  * bother with the "$@" magic.
 284                  */
 285                 if (!argv[1])
 286                         strvec_push(out, argv[0]);
 287                 else
 288                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 289         }
 290
 291         strvec_pushv(out, argv);
 292         return out->v;
 293 }
 294
 295 #ifndef GIT_WINDOWS_NATIVE
 296 static int child_notifier = -1;
 297
 298 enum child_errcode {
 299         CHILD_ERR_CHDIR,
 300         CHILD_ERR_DUP2,
 301         CHILD_ERR_CLOSE,
 302         CHILD_ERR_SIGPROCMASK,
 303         CHILD_ERR_ENOENT,
 304         CHILD_ERR_SILENT,
 305         CHILD_ERR_ERRNO
 306 };
 307
 308 struct child_err {
 309         enum child_errcode err;
 310         int syserr; /* errno */
 311 };
 312
 313 static void child_die(enum child_errcode err)
 314 {
 315         struct child_err buf;
 316
 317         buf.err = err;
 318         buf.syserr = errno;
 319
 320         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 321         xwrite(child_notifier, &buf, sizeof(buf));
 322         _exit(1);
 323 }
 324
 325 static void child_dup2(int fd, int to)
 326 {
 327         if (dup2(fd, to) < 0)
 328                 child_die(CHILD_ERR_DUP2);
 329 }
 330
 331 static void child_close(int fd)
 332 {
 333         if (close(fd))
 334                 child_die(CHILD_ERR_CLOSE);
 335 }
 336
 337 static void child_close_pair(int fd[2])
 338 {
 339         child_close(fd[0]);
 340         child_close(fd[1]);
 341 }
 342
 343 /*
 344  * parent will make it look like the child spewed a fatal error and died
 345  * this is needed to prevent changes to t0061.
 346  */
 347 static void fake_fatal(const char *err, va_list params)
 348 {
 349         vreportf("fatal: ", err, params);
 350 }
 351
 352 static void child_error_fn(const char *err, va_list params)
 353 {
 354         const char msg[] = "error() should not be called in child\n";
 355         xwrite(2, msg, sizeof(msg) - 1);
 356 }
 357
 358 static void child_warn_fn(const char *err, va_list params)
 359 {
 360         const char msg[] = "warn() should not be called in child\n";
 361         xwrite(2, msg, sizeof(msg) - 1);
 362 }
 363
 364 static void NORETURN child_die_fn(const char *err, va_list params)
 365 {
 366         const char msg[] = "die() should not be called in child\n";
 367         xwrite(2, msg, sizeof(msg) - 1);
 368         _exit(2);
 369 }
 370
 371 /* this runs in the parent process */
 372 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 373 {
 374         static void (*old_errfn)(const char *err, va_list params);
 375
 376         old_errfn = get_error_routine();
 377         set_error_routine(fake_fatal);
 378         errno = cerr->syserr;
 379
 380         switch (cerr->err) {
 381         case CHILD_ERR_CHDIR:
 382                 error_errno("exec '%s': cd to '%s' failed",
 383                             cmd->argv[0], cmd->dir);
 384                 break;
 385         case CHILD_ERR_DUP2:
 386                 error_errno("dup2() in child failed");
 387                 break;
 388         case CHILD_ERR_CLOSE:
 389                 error_errno("close() in child failed");
 390                 break;
 391         case CHILD_ERR_SIGPROCMASK:
 392                 error_errno("sigprocmask failed restoring signals");
 393                 break;
 394         case CHILD_ERR_ENOENT:
 395                 error_errno("cannot run %s", cmd->argv[0]);
 396                 break;
 397         case CHILD_ERR_SILENT:
 398                 break;
 399         case CHILD_ERR_ERRNO:
 400                 error_errno("cannot exec '%s'", cmd->argv[0]);
 401                 break;
 402         }
 403         set_error_routine(old_errfn);
 404 }
 405
 406 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 407 {
 408         if (!cmd->argv[0])
 409                 BUG("command is empty");
 410
 411         /*
 412          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 413          * attempt to interpret the command with 'sh'.
 414          */
 415         strvec_push(out, SHELL_PATH);
 416
 417         if (cmd->git_cmd) {
 418                 prepare_git_cmd(out, cmd->argv);
 419         } else if (cmd->use_shell) {
 420                 prepare_shell_cmd(out, cmd->argv);
 421         } else {
 422                 strvec_pushv(out, cmd->argv);
 423         }
 424
 425         /*
 426          * If there are no dir separator characters in the command then perform
 427          * a path lookup and use the resolved path as the command to exec. If
 428          * there are dir separator characters, we have exec attempt to invoke
 429          * the command directly.
 430          */
 431         if (!has_dir_sep(out->v[1])) {
 432                 char *program = locate_in_PATH(out->v[1]);
 433                 if (program) {
 434                         free((char *)out->v[1]);
 435                         out->v[1] = program;
 436                 } else {
 437                         strvec_clear(out);
 438                         errno = ENOENT;
 439                         return -1;
 440                 }
 441         }
 442
 443         return 0;
 444 }
 445
 446 static char **prep_childenv(const char *const *deltaenv)
 447 {
 448         extern char **environ;
 449         char **childenv;
 450         struct string_list env = STRING_LIST_INIT_DUP;
 451         struct strbuf key = STRBUF_INIT;
 452         const char *const *p;
 453         int i;
 454
 455         /* Construct a sorted string list consisting of the current environ */
 456         for (p = (const char *const *) environ; p && *p; p++) {
 457                 const char *equals = strchr(*p, '=');
 458
 459                 if (equals) {
 460                         strbuf_reset(&key);
 461                         strbuf_add(&key, *p, equals - *p);
 462                         string_list_append(&env, key.buf)->util = (void *) *p;
 463                 } else {
 464                         string_list_append(&env, *p)->util = (void *) *p;
 465                 }
 466         }
 467         string_list_sort(&env);
 468
 469         /* Merge in 'deltaenv' with the current environ */
 470         for (p = deltaenv; p && *p; p++) {
 471                 const char *equals = strchr(*p, '=');
 472
 473                 if (equals) {
 474                         /* ('key=value'), insert or replace entry */
 475                         strbuf_reset(&key);
 476                         strbuf_add(&key, *p, equals - *p);
 477                         string_list_insert(&env, key.buf)->util = (void *) *p;
 478                 } else {
 479                         /* otherwise ('key') remove existing entry */
 480                         string_list_remove(&env, *p, 0);
 481                 }
 482         }
 483
 484         /* Create an array of 'char *' to be used as the childenv */
 485         ALLOC_ARRAY(childenv, env.nr + 1);
 486         for (i = 0; i < env.nr; i++)
 487                 childenv[i] = env.items[i].util;
 488         childenv[env.nr] = NULL;
 489
 490         string_list_clear(&env, 0);
 491         strbuf_release(&key);
 492         return childenv;
 493 }
 494
 495 struct atfork_state {
 496 #ifndef NO_PTHREADS
 497         int cs;
 498 #endif
 499         sigset_t old;
 500 };
 501
 502 #define CHECK_BUG(err, msg) \
 503         do { \
 504                 int e = (err); \
 505                 if (e) \
 506                         BUG("%s: %s", msg, strerror(e)); \
 507         } while(0)
 508
 509 static void atfork_prepare(struct atfork_state *as)
 510 {
 511         sigset_t all;
 512
 513         if (sigfillset(&all))
 514                 die_errno("sigfillset");
 515 #ifdef NO_PTHREADS
 516         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 517                 die_errno("sigprocmask");
 518 #else
 519         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 520                 "blocking all signals");
 521         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 522                 "disabling cancellation");
 523 #endif
 524 }
 525
 526 static void atfork_parent(struct atfork_state *as)
 527 {
 528 #ifdef NO_PTHREADS
 529         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 530                 die_errno("sigprocmask");
 531 #else
 532         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 533                 "re-enabling cancellation");
 534         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 535                 "restoring signal mask");
 536 #endif
 537 }
 538 #endif /* GIT_WINDOWS_NATIVE */
 539
 540 static inline void set_cloexec(int fd)
 541 {
 542         int flags = fcntl(fd, F_GETFD);
 543         if (flags >= 0)
 544                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 545 }
 546
 547 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 548 {
 549         int status, code = -1;
 550         pid_t waiting;
 551         int failed_errno = 0;
 552
 553         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 554                 ;       /* nothing */
 555         if (in_signal) {
 556                 if (WIFEXITED(status))
 557                         code = WEXITSTATUS(status);
 558                 return code;
 559         }
 560
 561         if (waiting < 0) {
 562                 failed_errno = errno;
 563                 error_errno("waitpid for %s failed", argv0);
 564         } else if (waiting != pid) {
 565                 error("waitpid is confused (%s)", argv0);
 566         } else if (WIFSIGNALED(status)) {
 567                 code = WTERMSIG(status);
 568                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 569                         error("%s died of signal %d", argv0, code);
 570                 /*
 571                  * This return value is chosen so that code & 0xff
 572                  * mimics the exit code that a POSIX shell would report for
 573                  * a program that died from this signal.
 574                  */
 575                 code += 128;
 576         } else if (WIFEXITED(status)) {
 577                 code = WEXITSTATUS(status);
 578         } else {
 579                 error("waitpid is confused (%s)", argv0);
 580         }
 581
 582         clear_child_for_cleanup(pid);
 583
 584         errno = failed_errno;
 585         return code;
 586 }
 587
 588 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 589 {
 590         struct string_list envs = STRING_LIST_INIT_DUP;
 591         const char *const *e;
 592         int i;
 593         int printed_unset = 0;
 594
 595         /* Last one wins, see run-command.c:prep_childenv() for context */
 596         for (e = deltaenv; e && *e; e++) {
 597                 struct strbuf key = STRBUF_INIT;
 598                 char *equals = strchr(*e, '=');
 599
 600                 if (equals) {
 601                         strbuf_add(&key, *e, equals - *e);
 602                         string_list_insert(&envs, key.buf)->util = equals + 1;
 603                 } else {
 604                         string_list_insert(&envs, *e)->util = NULL;
 605                 }
 606                 strbuf_release(&key);
 607         }
 608
 609         /* "unset X Y...;" */
 610         for (i = 0; i < envs.nr; i++) {
 611                 const char *var = envs.items[i].string;
 612                 const char *val = envs.items[i].util;
 613
 614                 if (val || !getenv(var))
 615                         continue;
 616
 617                 if (!printed_unset) {
 618                         strbuf_addstr(dst, " unset");
 619                         printed_unset = 1;
 620                 }
 621                 strbuf_addf(dst, " %s", var);
 622         }
 623         if (printed_unset)
 624                 strbuf_addch(dst, ';');
 625
 626         /* ... followed by "A=B C=D ..." */
 627         for (i = 0; i < envs.nr; i++) {
 628                 const char *var = envs.items[i].string;
 629                 const char *val = envs.items[i].util;
 630                 const char *oldval;
 631
 632                 if (!val)
 633                         continue;
 634
 635                 oldval = getenv(var);
 636                 if (oldval && !strcmp(val, oldval))
 637                         continue;
 638
 639                 strbuf_addf(dst, " %s=", var);
 640                 sq_quote_buf_pretty(dst, val);
 641         }
 642         string_list_clear(&envs, 0);
 643 }
 644
 645 static void trace_run_command(const struct child_process *cp)
 646 {
 647         struct strbuf buf = STRBUF_INIT;
 648
 649         if (!trace_want(&trace_default_key))
 650                 return;
 651
 652         strbuf_addstr(&buf, "trace: run_command:");
 653         if (cp->dir) {
 654                 strbuf_addstr(&buf, " cd ");
 655                 sq_quote_buf_pretty(&buf, cp->dir);
 656                 strbuf_addch(&buf, ';');
 657         }
 658         /*
 659          * The caller is responsible for initializing cp->env from
 660          * cp->env_array if needed. We only check one place.
 661          */
 662         if (cp->env)
 663                 trace_add_env(&buf, cp->env);
 664         if (cp->git_cmd)
 665                 strbuf_addstr(&buf, " git");
 666         sq_quote_argv_pretty(&buf, cp->argv);
 667
 668         trace_printf("%s", buf.buf);
 669         strbuf_release(&buf);
 670 }
 671
 672 int start_command(struct child_process *cmd)
 673 {
 674         int need_in, need_out, need_err;
 675         int fdin[2], fdout[2], fderr[2];
 676         int failed_errno;
 677         char *str;
 678
 679         if (!cmd->argv)
 680                 cmd->argv = cmd->args.v;
 681         if (!cmd->env)
 682                 cmd->env = cmd->env_array.v;
 683
 684         /*
 685          * In case of errors we must keep the promise to close FDs
 686          * that have been passed in via ->in and ->out.
 687          */
 688
 689         need_in = !cmd->no_stdin && cmd->in < 0;
 690         if (need_in) {
 691                 if (pipe(fdin) < 0) {
 692                         failed_errno = errno;
 693                         if (cmd->out > 0)
 694                                 close(cmd->out);
 695                         str = "standard input";
 696                         goto fail_pipe;
 697                 }
 698                 cmd->in = fdin[1];
 699         }
 700
 701         need_out = !cmd->no_stdout
 702                 && !cmd->stdout_to_stderr
 703                 && cmd->out < 0;
 704         if (need_out) {
 705                 if (pipe(fdout) < 0) {
 706                         failed_errno = errno;
 707                         if (need_in)
 708                                 close_pair(fdin);
 709                         else if (cmd->in)
 710                                 close(cmd->in);
 711                         str = "standard output";
 712                         goto fail_pipe;
 713                 }
 714                 cmd->out = fdout[0];
 715         }
 716
 717         need_err = !cmd->no_stderr && cmd->err < 0;
 718         if (need_err) {
 719                 if (pipe(fderr) < 0) {
 720                         failed_errno = errno;
 721                         if (need_in)
 722                                 close_pair(fdin);
 723                         else if (cmd->in)
 724                                 close(cmd->in);
 725                         if (need_out)
 726                                 close_pair(fdout);
 727                         else if (cmd->out)
 728                                 close(cmd->out);
 729                         str = "standard error";
 730 fail_pipe:
 731                         error("cannot create %s pipe for %s: %s",
 732                                 str, cmd->argv[0], strerror(failed_errno));
 733                         child_process_clear(cmd);
 734                         errno = failed_errno;
 735                         return -1;
 736                 }
 737                 cmd->err = fderr[0];
 738         }
 739
 740         trace2_child_start(cmd);
 741         trace_run_command(cmd);
 742
 743         fflush(NULL);
 744
 745 #ifndef GIT_WINDOWS_NATIVE
 746 {
 747         int notify_pipe[2];
 748         int null_fd = -1;
 749         char **childenv;
 750         struct strvec argv = STRVEC_INIT;
 751         struct child_err cerr;
 752         struct atfork_state as;
 753
 754         if (prepare_cmd(&argv, cmd) < 0) {
 755                 failed_errno = errno;
 756                 cmd->pid = -1;
 757                 if (!cmd->silent_exec_failure)
 758                         error_errno("cannot run %s", cmd->argv[0]);
 759                 goto end_of_spawn;
 760         }
 761
 762         if (pipe(notify_pipe))
 763                 notify_pipe[0] = notify_pipe[1] = -1;
 764
 765         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 766                 null_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
 767                 if (null_fd < 0)
 768                         die_errno(_("open /dev/null failed"));
 769                 set_cloexec(null_fd);
 770         }
 771
 772         childenv = prep_childenv(cmd->env);
 773         atfork_prepare(&as);
 774
 775         /*
 776          * NOTE: In order to prevent deadlocking when using threads special
 777          * care should be taken with the function calls made in between the
 778          * fork() and exec() calls.  No calls should be made to functions which
 779          * require acquiring a lock (e.g. malloc) as the lock could have been
 780          * held by another thread at the time of forking, causing the lock to
 781          * never be released in the child process.  This means only
 782          * Async-Signal-Safe functions are permitted in the child.
 783          */
 784         cmd->pid = fork();
 785         failed_errno = errno;
 786         if (!cmd->pid) {
 787                 int sig;
 788                 /*
 789                  * Ensure the default die/error/warn routines do not get
 790                  * called, they can take stdio locks and malloc.
 791                  */
 792                 set_die_routine(child_die_fn);
 793                 set_error_routine(child_error_fn);
 794                 set_warn_routine(child_warn_fn);
 795
 796                 close(notify_pipe[0]);
 797                 set_cloexec(notify_pipe[1]);
 798                 child_notifier = notify_pipe[1];
 799
 800                 if (cmd->no_stdin)
 801                         child_dup2(null_fd, 0);
 802                 else if (need_in) {
 803                         child_dup2(fdin[0], 0);
 804                         child_close_pair(fdin);
 805                 } else if (cmd->in) {
 806                         child_dup2(cmd->in, 0);
 807                         child_close(cmd->in);
 808                 }
 809
 810                 if (cmd->no_stderr)
 811                         child_dup2(null_fd, 2);
 812                 else if (need_err) {
 813                         child_dup2(fderr[1], 2);
 814                         child_close_pair(fderr);
 815                 } else if (cmd->err > 1) {
 816                         child_dup2(cmd->err, 2);
 817                         child_close(cmd->err);
 818                 }
 819
 820                 if (cmd->no_stdout)
 821                         child_dup2(null_fd, 1);
 822                 else if (cmd->stdout_to_stderr)
 823                         child_dup2(2, 1);
 824                 else if (need_out) {
 825                         child_dup2(fdout[1], 1);
 826                         child_close_pair(fdout);
 827                 } else if (cmd->out > 1) {
 828                         child_dup2(cmd->out, 1);
 829                         child_close(cmd->out);
 830                 }
 831
 832                 if (cmd->dir && chdir(cmd->dir))
 833                         child_die(CHILD_ERR_CHDIR);
 834
 835                 /*
 836                  * restore default signal handlers here, in case
 837                  * we catch a signal right before execve below
 838                  */
 839                 for (sig = 1; sig < NSIG; sig++) {
 840                         /* ignored signals get reset to SIG_DFL on execve */
 841                         if (signal(sig, SIG_DFL) == SIG_IGN)
 842                                 signal(sig, SIG_IGN);
 843                 }
 844
 845                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 846                         child_die(CHILD_ERR_SIGPROCMASK);
 847
 848                 /*
 849                  * Attempt to exec using the command and arguments starting at
 850                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 851                  * be used in the event exec failed with ENOEXEC at which point
 852                  * we will try to interpret the command using 'sh'.
 853                  */
 854                 execve(argv.v[1], (char *const *) argv.v + 1,
 855                        (char *const *) childenv);
 856                 if (errno == ENOEXEC)
 857                         execve(argv.v[0], (char *const *) argv.v,
 858                                (char *const *) childenv);
 859
 860                 if (errno == ENOENT) {
 861                         if (cmd->silent_exec_failure)
 862                                 child_die(CHILD_ERR_SILENT);
 863                         child_die(CHILD_ERR_ENOENT);
 864                 } else {
 865                         child_die(CHILD_ERR_ERRNO);
 866                 }
 867         }
 868         atfork_parent(&as);
 869         if (cmd->pid < 0)
 870                 error_errno("cannot fork() for %s", cmd->argv[0]);
 871         else if (cmd->clean_on_exit)
 872                 mark_child_for_cleanup(cmd->pid, cmd);
 873
 874         /*
 875          * Wait for child's exec. If the exec succeeds (or if fork()
 876          * failed), EOF is seen immediately by the parent. Otherwise, the
 877          * child process sends a child_err struct.
 878          * Note that use of this infrastructure is completely advisory,
 879          * therefore, we keep error checks minimal.
 880          */
 881         close(notify_pipe[1]);
 882         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 883                 /*
 884                  * At this point we know that fork() succeeded, but exec()
 885                  * failed. Errors have been reported to our stderr.
 886                  */
 887                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 888                 child_err_spew(cmd, &cerr);
 889                 failed_errno = errno;
 890                 cmd->pid = -1;
 891         }
 892         close(notify_pipe[0]);
 893
 894         if (null_fd >= 0)
 895                 close(null_fd);
 896         strvec_clear(&argv);
 897         free(childenv);
 898 }
 899 end_of_spawn:
 900
 901 #else
 902 {
 903         int fhin = 0, fhout = 1, fherr = 2;
 904         const char **sargv = cmd->argv;
 905         struct strvec nargv = STRVEC_INIT;
 906
 907         if (cmd->no_stdin)
 908                 fhin = open("/dev/null", O_RDWR);
 909         else if (need_in)
 910                 fhin = dup(fdin[0]);
 911         else if (cmd->in)
 912                 fhin = dup(cmd->in);
 913
 914         if (cmd->no_stderr)
 915                 fherr = open("/dev/null", O_RDWR);
 916         else if (need_err)
 917                 fherr = dup(fderr[1]);
 918         else if (cmd->err > 2)
 919                 fherr = dup(cmd->err);
 920
 921         if (cmd->no_stdout)
 922                 fhout = open("/dev/null", O_RDWR);
 923         else if (cmd->stdout_to_stderr)
 924                 fhout = dup(fherr);
 925         else if (need_out)
 926                 fhout = dup(fdout[1]);
 927         else if (cmd->out > 1)
 928                 fhout = dup(cmd->out);
 929
 930         if (cmd->git_cmd)
 931                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 932         else if (cmd->use_shell)
 933                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 934
 935         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 936                         cmd->dir, fhin, fhout, fherr);
 937         failed_errno = errno;
 938         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 939                 error_errno("cannot spawn %s", cmd->argv[0]);
 940         if (cmd->clean_on_exit && cmd->pid >= 0)
 941                 mark_child_for_cleanup(cmd->pid, cmd);
 942
 943         strvec_clear(&nargv);
 944         cmd->argv = sargv;
 945         if (fhin != 0)
 946                 close(fhin);
 947         if (fhout != 1)
 948                 close(fhout);
 949         if (fherr != 2)
 950                 close(fherr);
 951 }
 952 #endif
 953
 954         if (cmd->pid < 0) {
 955                 trace2_child_exit(cmd, -1);
 956
 957                 if (need_in)
 958                         close_pair(fdin);
 959                 else if (cmd->in)
 960                         close(cmd->in);
 961                 if (need_out)
 962                         close_pair(fdout);
 963                 else if (cmd->out)
 964                         close(cmd->out);
 965                 if (need_err)
 966                         close_pair(fderr);
 967                 else if (cmd->err)
 968                         close(cmd->err);
 969                 child_process_clear(cmd);
 970                 errno = failed_errno;
 971                 return -1;
 972         }
 973
 974         if (need_in)
 975                 close(fdin[0]);
 976         else if (cmd->in)
 977                 close(cmd->in);
 978
 979         if (need_out)
 980                 close(fdout[1]);
 981         else if (cmd->out)
 982                 close(cmd->out);
 983
 984         if (need_err)
 985                 close(fderr[1]);
 986         else if (cmd->err)
 987                 close(cmd->err);
 988
 989         return 0;
 990 }
 991
 992 int finish_command(struct child_process *cmd)
 993 {
 994         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 995         trace2_child_exit(cmd, ret);
 996         child_process_clear(cmd);
 997         invalidate_lstat_cache();
 998         return ret;
 999 }
1000
1001 int finish_command_in_signal(struct child_process *cmd)
1002 {
1003         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
1004         trace2_child_exit(cmd, ret);
1005         return ret;
1006 }
1007
1008
1009 int run_command(struct child_process *cmd)
1010 {
1011         int code;
1012
1013         if (cmd->out < 0 || cmd->err < 0)
1014                 BUG("run_command with a pipe can cause deadlock");
1015
1016         code = start_command(cmd);
1017         if (code)
1018                 return code;
1019         return finish_command(cmd);
1020 }
1021
1022 int run_command_v_opt(const char **argv, int opt)
1023 {
1024         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
1025 }
1026
1027 int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
1028 {
1029         return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
1030 }
1031
1032 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
1033 {
1034         return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
1035 }
1036
1037 int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
1038                                  const char *const *env, const char *tr2_class)
1039 {
1040         struct child_process cmd = CHILD_PROCESS_INIT;
1041         cmd.argv = argv;
1042         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
1043         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
1044         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
1045         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
1046         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
1047         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
1048         cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
1049         cmd.dir = dir;
1050         cmd.env = env;
1051         cmd.trace2_child_class = tr2_class;
1052         return run_command(&cmd);
1053 }
1054
1055 #ifndef NO_PTHREADS
1056 static pthread_t main_thread;
1057 static int main_thread_set;
1058 static pthread_key_t async_key;
1059 static pthread_key_t async_die_counter;
1060
1061 static void *run_thread(void *data)
1062 {
1063         struct async *async = data;
1064         intptr_t ret;
1065
1066         if (async->isolate_sigpipe) {
1067                 sigset_t mask;
1068                 sigemptyset(&mask);
1069                 sigaddset(&mask, SIGPIPE);
1070                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
1071                         ret = error("unable to block SIGPIPE in async thread");
1072                         return (void *)ret;
1073                 }
1074         }
1075
1076         pthread_setspecific(async_key, async);
1077         ret = async->proc(async->proc_in, async->proc_out, async->data);
1078         return (void *)ret;
1079 }
1080
1081 static NORETURN void die_async(const char *err, va_list params)
1082 {
1083         vreportf("fatal: ", err, params);
1084
1085         if (in_async()) {
1086                 struct async *async = pthread_getspecific(async_key);
1087                 if (async->proc_in >= 0)
1088                         close(async->proc_in);
1089                 if (async->proc_out >= 0)
1090                         close(async->proc_out);
1091                 pthread_exit((void *)128);
1092         }
1093
1094         exit(128);
1095 }
1096
1097 static int async_die_is_recursing(void)
1098 {
1099         void *ret = pthread_getspecific(async_die_counter);
1100         pthread_setspecific(async_die_counter, (void *)1);
1101         return ret != NULL;
1102 }
1103
1104 int in_async(void)
1105 {
1106         if (!main_thread_set)
1107                 return 0; /* no asyncs started yet */
1108         return !pthread_equal(main_thread, pthread_self());
1109 }
1110
1111 static void NORETURN async_exit(int code)
1112 {
1113         pthread_exit((void *)(intptr_t)code);
1114 }
1115
1116 #else
1117
1118 static struct {
1119         void (**handlers)(void);
1120         size_t nr;
1121         size_t alloc;
1122 } git_atexit_hdlrs;
1123
1124 static int git_atexit_installed;
1125
1126 static void git_atexit_dispatch(void)
1127 {
1128         size_t i;
1129
1130         for (i=git_atexit_hdlrs.nr ; i ; i--)
1131                 git_atexit_hdlrs.handlers[i-1]();
1132 }
1133
1134 static void git_atexit_clear(void)
1135 {
1136         free(git_atexit_hdlrs.handlers);
1137         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1138         git_atexit_installed = 0;
1139 }
1140
1141 #undef atexit
1142 int git_atexit(void (*handler)(void))
1143 {
1144         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1145         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1146         if (!git_atexit_installed) {
1147                 if (atexit(&git_atexit_dispatch))
1148                         return -1;
1149                 git_atexit_installed = 1;
1150         }
1151         return 0;
1152 }
1153 #define atexit git_atexit
1154
1155 static int process_is_async;
1156 int in_async(void)
1157 {
1158         return process_is_async;
1159 }
1160
1161 static void NORETURN async_exit(int code)
1162 {
1163         exit(code);
1164 }
1165
1166 #endif
1167
1168 void check_pipe(int err)
1169 {
1170         if (err == EPIPE) {
1171                 if (in_async())
1172                         async_exit(141);
1173
1174                 signal(SIGPIPE, SIG_DFL);
1175                 raise(SIGPIPE);
1176                 /* Should never happen, but just in case... */
1177                 exit(141);
1178         }
1179 }
1180
1181 int start_async(struct async *async)
1182 {
1183         int need_in, need_out;
1184         int fdin[2], fdout[2];
1185         int proc_in, proc_out;
1186
1187         need_in = async->in < 0;
1188         if (need_in) {
1189                 if (pipe(fdin) < 0) {
1190                         if (async->out > 0)
1191                                 close(async->out);
1192                         return error_errno("cannot create pipe");
1193                 }
1194                 async->in = fdin[1];
1195         }
1196
1197         need_out = async->out < 0;
1198         if (need_out) {
1199                 if (pipe(fdout) < 0) {
1200                         if (need_in)
1201                                 close_pair(fdin);
1202                         else if (async->in)
1203                                 close(async->in);
1204                         return error_errno("cannot create pipe");
1205                 }
1206                 async->out = fdout[0];
1207         }
1208
1209         if (need_in)
1210                 proc_in = fdin[0];
1211         else if (async->in)
1212                 proc_in = async->in;
1213         else
1214                 proc_in = -1;
1215
1216         if (need_out)
1217                 proc_out = fdout[1];
1218         else if (async->out)
1219                 proc_out = async->out;
1220         else
1221                 proc_out = -1;
1222
1223 #ifdef NO_PTHREADS
1224         /* Flush stdio before fork() to avoid cloning buffers */
1225         fflush(NULL);
1226
1227         async->pid = fork();
1228         if (async->pid < 0) {
1229                 error_errno("fork (async) failed");
1230                 goto error;
1231         }
1232         if (!async->pid) {
1233                 if (need_in)
1234                         close(fdin[1]);
1235                 if (need_out)
1236                         close(fdout[0]);
1237                 git_atexit_clear();
1238                 process_is_async = 1;
1239                 exit(!!async->proc(proc_in, proc_out, async->data));
1240         }
1241
1242         mark_child_for_cleanup(async->pid, NULL);
1243
1244         if (need_in)
1245                 close(fdin[0]);
1246         else if (async->in)
1247                 close(async->in);
1248
1249         if (need_out)
1250                 close(fdout[1]);
1251         else if (async->out)
1252                 close(async->out);
1253 #else
1254         if (!main_thread_set) {
1255                 /*
1256                  * We assume that the first time that start_async is called
1257                  * it is from the main thread.
1258                  */
1259                 main_thread_set = 1;
1260                 main_thread = pthread_self();
1261                 pthread_key_create(&async_key, NULL);
1262                 pthread_key_create(&async_die_counter, NULL);
1263                 set_die_routine(die_async);
1264                 set_die_is_recursing_routine(async_die_is_recursing);
1265         }
1266
1267         if (proc_in >= 0)
1268                 set_cloexec(proc_in);
1269         if (proc_out >= 0)
1270                 set_cloexec(proc_out);
1271         async->proc_in = proc_in;
1272         async->proc_out = proc_out;
1273         {
1274                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1275                 if (err) {
1276                         error(_("cannot create async thread: %s"), strerror(err));
1277                         goto error;
1278                 }
1279         }
1280 #endif
1281         return 0;
1282
1283 error:
1284         if (need_in)
1285                 close_pair(fdin);
1286         else if (async->in)
1287                 close(async->in);
1288
1289         if (need_out)
1290                 close_pair(fdout);
1291         else if (async->out)
1292                 close(async->out);
1293         return -1;
1294 }
1295
1296 int finish_async(struct async *async)
1297 {
1298 #ifdef NO_PTHREADS
1299         int ret = wait_or_whine(async->pid, "child process", 0);
1300
1301         invalidate_lstat_cache();
1302
1303         return ret;
1304 #else
1305         void *ret = (void *)(intptr_t)(-1);
1306
1307         if (pthread_join(async->tid, &ret))
1308                 error("pthread_join failed");
1309         invalidate_lstat_cache();
1310         return (int)(intptr_t)ret;
1311
1312 #endif
1313 }
1314
1315 int async_with_fork(void)
1316 {
1317 #ifdef NO_PTHREADS
1318         return 1;
1319 #else
1320         return 0;
1321 #endif
1322 }
1323
1324 struct io_pump {
1325         /* initialized by caller */
1326         int fd;
1327         int type; /* POLLOUT or POLLIN */
1328         union {
1329                 struct {
1330                         const char *buf;
1331                         size_t len;
1332                 } out;
1333                 struct {
1334                         struct strbuf *buf;
1335                         size_t hint;
1336                 } in;
1337         } u;
1338
1339         /* returned by pump_io */
1340         int error; /* 0 for success, otherwise errno */
1341
1342         /* internal use */
1343         struct pollfd *pfd;
1344 };
1345
1346 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1347 {
1348         int pollsize = 0;
1349         int i;
1350
1351         for (i = 0; i < nr; i++) {
1352                 struct io_pump *io = &slots[i];
1353                 if (io->fd < 0)
1354                         continue;
1355                 pfd[pollsize].fd = io->fd;
1356                 pfd[pollsize].events = io->type;
1357                 io->pfd = &pfd[pollsize++];
1358         }
1359
1360         if (!pollsize)
1361                 return 0;
1362
1363         if (poll(pfd, pollsize, -1) < 0) {
1364                 if (errno == EINTR)
1365                         return 1;
1366                 die_errno("poll failed");
1367         }
1368
1369         for (i = 0; i < nr; i++) {
1370                 struct io_pump *io = &slots[i];
1371
1372                 if (io->fd < 0)
1373                         continue;
1374
1375                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1376                         continue;
1377
1378                 if (io->type == POLLOUT) {
1379                         ssize_t len = xwrite(io->fd,
1380                                              io->u.out.buf, io->u.out.len);
1381                         if (len < 0) {
1382                                 io->error = errno;
1383                                 close(io->fd);
1384                                 io->fd = -1;
1385                         } else {
1386                                 io->u.out.buf += len;
1387                                 io->u.out.len -= len;
1388                                 if (!io->u.out.len) {
1389                                         close(io->fd);
1390                                         io->fd = -1;
1391                                 }
1392                         }
1393                 }
1394
1395                 if (io->type == POLLIN) {
1396                         ssize_t len = strbuf_read_once(io->u.in.buf,
1397                                                        io->fd, io->u.in.hint);
1398                         if (len < 0)
1399                                 io->error = errno;
1400                         if (len <= 0) {
1401                                 close(io->fd);
1402                                 io->fd = -1;
1403                         }
1404                 }
1405         }
1406
1407         return 1;
1408 }
1409
1410 static int pump_io(struct io_pump *slots, int nr)
1411 {
1412         struct pollfd *pfd;
1413         int i;
1414
1415         for (i = 0; i < nr; i++)
1416                 slots[i].error = 0;
1417
1418         ALLOC_ARRAY(pfd, nr);
1419         while (pump_io_round(slots, nr, pfd))
1420                 ; /* nothing */
1421         free(pfd);
1422
1423         /* There may be multiple errno values, so just pick the first. */
1424         for (i = 0; i < nr; i++) {
1425                 if (slots[i].error) {
1426                         errno = slots[i].error;
1427                         return -1;
1428                 }
1429         }
1430         return 0;
1431 }
1432
1433
1434 int pipe_command(struct child_process *cmd,
1435                  const char *in, size_t in_len,
1436                  struct strbuf *out, size_t out_hint,
1437                  struct strbuf *err, size_t err_hint)
1438 {
1439         struct io_pump io[3];
1440         int nr = 0;
1441
1442         if (in)
1443                 cmd->in = -1;
1444         if (out)
1445                 cmd->out = -1;
1446         if (err)
1447                 cmd->err = -1;
1448
1449         if (start_command(cmd) < 0)
1450                 return -1;
1451
1452         if (in) {
1453                 io[nr].fd = cmd->in;
1454                 io[nr].type = POLLOUT;
1455                 io[nr].u.out.buf = in;
1456                 io[nr].u.out.len = in_len;
1457                 nr++;
1458         }
1459         if (out) {
1460                 io[nr].fd = cmd->out;
1461                 io[nr].type = POLLIN;
1462                 io[nr].u.in.buf = out;
1463                 io[nr].u.in.hint = out_hint;
1464                 nr++;
1465         }
1466         if (err) {
1467                 io[nr].fd = cmd->err;
1468                 io[nr].type = POLLIN;
1469                 io[nr].u.in.buf = err;
1470                 io[nr].u.in.hint = err_hint;
1471                 nr++;
1472         }
1473
1474         if (pump_io(io, nr) < 0) {
1475                 finish_command(cmd); /* throw away exit code */
1476                 return -1;
1477         }
1478
1479         return finish_command(cmd);
1480 }
1481
1482 enum child_state {
1483         GIT_CP_FREE,
1484         GIT_CP_WORKING,
1485         GIT_CP_WAIT_CLEANUP,
1486 };
1487
1488 struct parallel_processes {
1489         void *data;
1490
1491         int max_processes;
1492         int nr_processes;
1493
1494         get_next_task_fn get_next_task;
1495         start_failure_fn start_failure;
1496         feed_pipe_fn feed_pipe;
1497         consume_sideband_fn consume_sideband;
1498         task_finished_fn task_finished;
1499
1500         struct {
1501                 enum child_state state;
1502                 struct child_process process;
1503                 struct strbuf err;
1504                 void *data;
1505         } *children;
1506         /*
1507          * The struct pollfd is logically part of *children,
1508          * but the system call expects it as its own array.
1509          */
1510         struct pollfd *pfd;
1511
1512         unsigned shutdown : 1;
1513
1514         int output_owner;
1515         struct strbuf buffered_output; /* of finished children */
1516 };
1517
1518 static int default_start_failure(struct strbuf *out,
1519                                  void *pp_cb,
1520                                  void *pp_task_cb)
1521 {
1522         return 0;
1523 }
1524
1525 static int default_feed_pipe(struct strbuf *pipe,
1526                              void *pp_cb,
1527                              void *pp_task_cb)
1528 {
1529         return 1;
1530 }
1531
1532 static int default_task_finished(int result,
1533                                  struct strbuf *out,
1534                                  void *pp_cb,
1535                                  void *pp_task_cb)
1536 {
1537         return 0;
1538 }
1539
1540 static void kill_children(struct parallel_processes *pp, int signo)
1541 {
1542         int i, n = pp->max_processes;
1543
1544         for (i = 0; i < n; i++)
1545                 if (pp->children[i].state == GIT_CP_WORKING)
1546                         kill(pp->children[i].process.pid, signo);
1547 }
1548
1549 static struct parallel_processes *pp_for_signal;
1550
1551 static void handle_children_on_signal(int signo)
1552 {
1553         kill_children(pp_for_signal, signo);
1554         sigchain_pop(signo);
1555         raise(signo);
1556 }
1557
1558 static void pp_init(struct parallel_processes *pp,
1559                     int n,
1560                     get_next_task_fn get_next_task,
1561                     start_failure_fn start_failure,
1562                     feed_pipe_fn feed_pipe,
1563                     consume_sideband_fn consume_sideband,
1564                     task_finished_fn task_finished,
1565                     void *data)
1566 {
1567         int i;
1568
1569         if (n < 1)
1570                 n = online_cpus();
1571
1572         pp->max_processes = n;
1573
1574         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1575
1576         pp->data = data;
1577         if (!get_next_task)
1578                 BUG("you need to specify a get_next_task function");
1579         pp->get_next_task = get_next_task;
1580
1581         pp->start_failure = start_failure ? start_failure : default_start_failure;
1582         pp->feed_pipe = feed_pipe ? feed_pipe : default_feed_pipe;
1583         pp->task_finished = task_finished ? task_finished : default_task_finished;
1584         pp->consume_sideband = consume_sideband;
1585
1586         pp->nr_processes = 0;
1587         pp->output_owner = 0;
1588         pp->shutdown = 0;
1589         CALLOC_ARRAY(pp->children, n);
1590         CALLOC_ARRAY(pp->pfd, n);
1591         strbuf_init(&pp->buffered_output, 0);
1592
1593         for (i = 0; i < n; i++) {
1594                 strbuf_init(&pp->children[i].err, 0);
1595                 child_process_init(&pp->children[i].process);
1596                 pp->pfd[i].events = POLLIN | POLLHUP;
1597                 pp->pfd[i].fd = -1;
1598         }
1599
1600         pp_for_signal = pp;
1601         sigchain_push_common(handle_children_on_signal);
1602 }
1603
1604 static void pp_cleanup(struct parallel_processes *pp)
1605 {
1606         int i;
1607
1608         trace_printf("run_processes_parallel: done");
1609         for (i = 0; i < pp->max_processes; i++) {
1610                 strbuf_release(&pp->children[i].err);
1611                 child_process_clear(&pp->children[i].process);
1612         }
1613
1614         free(pp->children);
1615         free(pp->pfd);
1616
1617         /*
1618          * When get_next_task added messages to the buffer in its last
1619          * iteration, the buffered output is non empty.
1620          */
1621         if (pp->consume_sideband)
1622                 pp->consume_sideband(&pp->buffered_output, pp->data);
1623         else
1624                 strbuf_write(&pp->buffered_output, stderr);
1625         strbuf_release(&pp->buffered_output);
1626
1627         sigchain_pop_common();
1628 }
1629
1630 /* returns
1631  *  0 if a new task was started.
1632  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1633  *    problem with starting a new command)
1634  * <0 no new job was started, user wishes to shutdown early. Use negative code
1635  *    to signal the children.
1636  */
1637 static int pp_start_one(struct parallel_processes *pp)
1638 {
1639         int i, code;
1640
1641         for (i = 0; i < pp->max_processes; i++)
1642                 if (pp->children[i].state == GIT_CP_FREE)
1643                         break;
1644         if (i == pp->max_processes)
1645                 BUG("bookkeeping is hard");
1646
1647         /*
1648          * By default, do not inherit stdin from the parent process - otherwise,
1649          * all children would share stdin! Users may overwrite this to provide
1650          * something to the child's stdin by having their 'get_next_task'
1651          * callback assign 0 to .no_stdin and an appropriate integer to .in.
1652          */
1653         pp->children[i].process.no_stdin = 1;
1654
1655         code = pp->get_next_task(&pp->children[i].process,
1656                                  &pp->children[i].err,
1657                                  pp->data,
1658                                  &pp->children[i].data);
1659         if (!code) {
1660                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1661                 strbuf_reset(&pp->children[i].err);
1662                 return 1;
1663         }
1664         pp->children[i].process.err = -1;
1665         pp->children[i].process.stdout_to_stderr = 1;
1666
1667         if (start_command(&pp->children[i].process)) {
1668                 code = pp->start_failure(&pp->children[i].err,
1669                                          pp->data,
1670                                          pp->children[i].data);
1671                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1672                 strbuf_reset(&pp->children[i].err);
1673                 if (code)
1674                         pp->shutdown = 1;
1675                 return code;
1676         }
1677
1678         pp->nr_processes++;
1679         pp->children[i].state = GIT_CP_WORKING;
1680         pp->pfd[i].fd = pp->children[i].process.err;
1681         return 0;
1682 }
1683
1684 static void pp_buffer_stdin(struct parallel_processes *pp)
1685 {
1686         int i;
1687         struct strbuf sb = STRBUF_INIT;
1688
1689         /* Buffer stdin for each pipe. */
1690         for (i = 0; i < pp->max_processes; i++) {
1691                 if (pp->children[i].state == GIT_CP_WORKING &&
1692                     pp->children[i].process.in > 0) {
1693                         int done;
1694                         strbuf_reset(&sb);
1695                         done = pp->feed_pipe(&sb, pp->data,
1696                                               pp->children[i].data);
1697                         if (sb.len) {
1698                                 if (write_in_full(pp->children[i].process.in,
1699                                               sb.buf, sb.len) < 0) {
1700                                         if (errno != EPIPE)
1701                                                 die_errno("write");
1702                                         done = 1;
1703                                 }
1704                         }
1705                         if (done) {
1706                                 close(pp->children[i].process.in);
1707                                 pp->children[i].process.in = 0;
1708                         }
1709                 }
1710         }
1711
1712         strbuf_release(&sb);
1713 }
1714
1715 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1716 {
1717         int i;
1718
1719         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1720                 if (errno == EINTR)
1721                         continue;
1722                 pp_cleanup(pp);
1723                 die_errno("poll");
1724         }
1725
1726         /* Buffer output from all pipes. */
1727         for (i = 0; i < pp->max_processes; i++) {
1728                 if (pp->children[i].state == GIT_CP_WORKING &&
1729                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1730                         int n = strbuf_read_once(&pp->children[i].err,
1731                                                  pp->children[i].process.err, 0);
1732                         if (n == 0) {
1733                                 close(pp->children[i].process.err);
1734                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1735                         } else if (n < 0)
1736                                 if (errno != EAGAIN)
1737                                         die_errno("read");
1738                 }
1739         }
1740 }
1741
1742 static void pp_output(struct parallel_processes *pp)
1743 {
1744         int i = pp->output_owner;
1745
1746         if (pp->children[i].state == GIT_CP_WORKING &&
1747             pp->children[i].err.len) {
1748                 if (pp->consume_sideband)
1749                         pp->consume_sideband(&pp->children[i].err, pp->data);
1750                 else
1751                         strbuf_write(&pp->children[i].err, stderr);
1752                 strbuf_reset(&pp->children[i].err);
1753         }
1754 }
1755
1756 static int pp_collect_finished(struct parallel_processes *pp)
1757 {
1758         int i, code;
1759         int n = pp->max_processes;
1760         int result = 0;
1761
1762         while (pp->nr_processes > 0) {
1763                 for (i = 0; i < pp->max_processes; i++)
1764                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1765                                 break;
1766                 if (i == pp->max_processes)
1767                         break;
1768
1769                 code = finish_command(&pp->children[i].process);
1770
1771                 code = pp->task_finished(code,
1772                                          &pp->children[i].err, pp->data,
1773                                          pp->children[i].data);
1774
1775                 if (code)
1776                         result = code;
1777                 if (code < 0)
1778                         break;
1779
1780                 pp->nr_processes--;
1781                 pp->children[i].state = GIT_CP_FREE;
1782                 pp->pfd[i].fd = -1;
1783                 pp->children[i].process.in = 0;
1784                 child_process_init(&pp->children[i].process);
1785
1786                 if (i != pp->output_owner) {
1787                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1788                         strbuf_reset(&pp->children[i].err);
1789                 } else {
1790                         /* Output errors, then all other finished child processes */
1791                         if (pp->consume_sideband) {
1792                                 pp->consume_sideband(&pp->children[i].err, pp->data);
1793                                 pp->consume_sideband(&pp->buffered_output, pp->data);
1794                         } else {
1795                                 strbuf_write(&pp->children[i].err, stderr);
1796                                 strbuf_write(&pp->buffered_output, stderr);
1797                         }
1798                         strbuf_reset(&pp->children[i].err);
1799                         strbuf_reset(&pp->buffered_output);
1800
1801                         /*
1802                          * Pick next process to output live.
1803                          * NEEDSWORK:
1804                          * For now we pick it randomly by doing a round
1805                          * robin. Later we may want to pick the one with
1806                          * the most output or the longest or shortest
1807                          * running process time.
1808                          */
1809                         for (i = 0; i < n; i++)
1810                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1811                                         break;
1812                         pp->output_owner = (pp->output_owner + i) % n;
1813                 }
1814         }
1815         return result;
1816 }
1817
1818 int run_processes_parallel(int n,
1819                            get_next_task_fn get_next_task,
1820                            start_failure_fn start_failure,
1821                            feed_pipe_fn feed_pipe,
1822                            consume_sideband_fn consume_sideband,
1823                            task_finished_fn task_finished,
1824                            void *pp_cb)
1825 {
1826         int i, code;
1827         int output_timeout = 100;
1828         int spawn_cap = 4;
1829         struct parallel_processes pp;
1830
1831         sigchain_push(SIGPIPE, SIG_IGN);
1832
1833         pp_init(&pp, n, get_next_task, start_failure, feed_pipe, consume_sideband, task_finished, pp_cb);
1834         while (1) {
1835                 for (i = 0;
1836                     i < spawn_cap && !pp.shutdown &&
1837                     pp.nr_processes < pp.max_processes;
1838                     i++) {
1839                         code = pp_start_one(&pp);
1840                         if (!code)
1841                                 continue;
1842                         if (code < 0) {
1843                                 pp.shutdown = 1;
1844                                 kill_children(&pp, -code);
1845                         }
1846                         break;
1847                 }
1848                 if (!pp.nr_processes)
1849                         break;
1850                 pp_buffer_stdin(&pp);
1851                 pp_buffer_stderr(&pp, output_timeout);
1852                 pp_output(&pp);
1853                 code = pp_collect_finished(&pp);
1854                 if (code) {
1855                         pp.shutdown = 1;
1856                         if (code < 0)
1857                                 kill_children(&pp, -code);
1858                 }
1859         }
1860
1861         pp_cleanup(&pp);
1862
1863         sigchain_pop(SIGPIPE);
1864
1865         return 0;
1866 }
1867
1868 int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
1869                                start_failure_fn start_failure,
1870                                feed_pipe_fn feed_pipe,
1871                                consume_sideband_fn consume_sideband,
1872                                task_finished_fn task_finished, void *pp_cb,
1873                                const char *tr2_category, const char *tr2_label)
1874 {
1875         int result;
1876
1877         trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
1878                                    ((n < 1) ? online_cpus() : n));
1879
1880         result = run_processes_parallel(n, get_next_task, start_failure,
1881                                         feed_pipe, consume_sideband,
1882                                         task_finished, pp_cb);
1883
1884         trace2_region_leave(tr2_category, tr2_label, NULL);
1885
1886         return result;
1887 }
1888
1889 int run_auto_maintenance(int quiet)
1890 {
1891         int enabled;
1892         struct child_process maint = CHILD_PROCESS_INIT;
1893
1894         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1895             !enabled)
1896                 return 0;
1897
1898         maint.git_cmd = 1;
1899         strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
1900         strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
1901
1902         return run_command(&maint);
1903 }
1904
1905 void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir)
1906 {
1907         const char * const *var;
1908
1909         for (var = local_repo_env; *var; var++) {
1910                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1911                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1912                         strvec_push(env_array, *var);
1913         }
1914         strvec_pushf(env_array, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1915 }