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
  12 void child_process_init(struct child_process *child)
  13 {
  14         memset(child, 0, sizeof(*child));
  15         strvec_init(&child->args);
  16         strvec_init(&child->env_array);
  17 }
  18
  19 void child_process_clear(struct child_process *child)
  20 {
  21         strvec_clear(&child->args);
  22         strvec_clear(&child->env_array);
  23 }
  24
  25 struct child_to_clean {
  26         pid_t pid;
  27         struct child_process *process;
  28         struct child_to_clean *next;
  29 };
  30 static struct child_to_clean *children_to_clean;
  31 static int installed_child_cleanup_handler;
  32
  33 static void cleanup_children(int sig, int in_signal)
  34 {
  35         struct child_to_clean *children_to_wait_for = NULL;
  36
  37         while (children_to_clean) {
  38                 struct child_to_clean *p = children_to_clean;
  39                 children_to_clean = p->next;
  40
  41                 if (p->process && !in_signal) {
  42                         struct child_process *process = p->process;
  43                         if (process->clean_on_exit_handler) {
  44                                 trace_printf(
  45                                         "trace: run_command: running exit handler for pid %"
  46                                         PRIuMAX, (uintmax_t)p->pid
  47                                 );
  48                                 process->clean_on_exit_handler(process);
  49                         }
  50                 }
  51
  52                 kill(p->pid, sig);
  53
  54                 if (p->process && p->process->wait_after_clean) {
  55                         p->next = children_to_wait_for;
  56                         children_to_wait_for = p;
  57                 } else {
  58                         if (!in_signal)
  59                                 free(p);
  60                 }
  61         }
  62
  63         while (children_to_wait_for) {
  64                 struct child_to_clean *p = children_to_wait_for;
  65                 children_to_wait_for = p->next;
  66
  67                 while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  68                         ; /* spin waiting for process exit or error */
  69
  70                 if (!in_signal)
  71                         free(p);
  72         }
  73 }
  74
  75 static void cleanup_children_on_signal(int sig)
  76 {
  77         cleanup_children(sig, 1);
  78         sigchain_pop(sig);
  79         raise(sig);
  80 }
  81
  82 static void cleanup_children_on_exit(void)
  83 {
  84         cleanup_children(SIGTERM, 0);
  85 }
  86
  87 static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  88 {
  89         struct child_to_clean *p = xmalloc(sizeof(*p));
  90         p->pid = pid;
  91         p->process = process;
  92         p->next = children_to_clean;
  93         children_to_clean = p;
  94
  95         if (!installed_child_cleanup_handler) {
  96                 atexit(cleanup_children_on_exit);
  97                 sigchain_push_common(cleanup_children_on_signal);
  98                 installed_child_cleanup_handler = 1;
  99         }
 100 }
 101
 102 static void clear_child_for_cleanup(pid_t pid)
 103 {
 104         struct child_to_clean **pp;
 105
 106         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 107                 struct child_to_clean *clean_me = *pp;
 108
 109                 if (clean_me->pid == pid) {
 110                         *pp = clean_me->next;
 111                         free(clean_me);
 112                         return;
 113                 }
 114         }
 115 }
 116
 117 static inline void close_pair(int fd[2])
 118 {
 119         close(fd[0]);
 120         close(fd[1]);
 121 }
 122
 123 int is_executable(const char *name)
 124 {
 125         struct stat st;
 126
 127         if (stat(name, &st) || /* stat, not lstat */
 128             !S_ISREG(st.st_mode))
 129                 return 0;
 130
 131 #if defined(GIT_WINDOWS_NATIVE)
 132         /*
 133          * On Windows there is no executable bit. The file extension
 134          * indicates whether it can be run as an executable, and Git
 135          * has special-handling to detect scripts and launch them
 136          * through the indicated script interpreter. We test for the
 137          * file extension first because virus scanners may make
 138          * it quite expensive to open many files.
 139          */
 140         if (ends_with(name, ".exe"))
 141                 return S_IXUSR;
 142
 143 {
 144         /*
 145          * Now that we know it does not have an executable extension,
 146          * peek into the file instead.
 147          */
 148         char buf[3] = { 0 };
 149         int n;
 150         int fd = open(name, O_RDONLY);
 151         st.st_mode &= ~S_IXUSR;
 152         if (fd >= 0) {
 153                 n = read(fd, buf, 2);
 154                 if (n == 2)
 155                         /* look for a she-bang */
 156                         if (!strcmp(buf, "#!"))
 157                                 st.st_mode |= S_IXUSR;
 158                 close(fd);
 159         }
 160 }
 161 #endif
 162         return st.st_mode & S_IXUSR;
 163 }
 164
 165 /*
 166  * Search $PATH for a command.  This emulates the path search that
 167  * execvp would perform, without actually executing the command so it
 168  * can be used before fork() to prepare to run a command using
 169  * execve() or after execvp() to diagnose why it failed.
 170  *
 171  * The caller should ensure that file contains no directory
 172  * separators.
 173  *
 174  * Returns the path to the command, as found in $PATH or NULL if the
 175  * command could not be found.  The caller inherits ownership of the memory
 176  * used to store the resultant path.
 177  *
 178  * This should not be used on Windows, where the $PATH search rules
 179  * are more complicated (e.g., a search for "foo" should find
 180  * "foo.exe").
 181  */
 182 static char *locate_in_PATH(const char *file)
 183 {
 184         const char *p = getenv("PATH");
 185         struct strbuf buf = STRBUF_INIT;
 186
 187         if (!p || !*p)
 188                 return NULL;
 189
 190         while (1) {
 191                 const char *end = strchrnul(p, ':');
 192
 193                 strbuf_reset(&buf);
 194
 195                 /* POSIX specifies an empty entry as the current directory. */
 196                 if (end != p) {
 197                         strbuf_add(&buf, p, end - p);
 198                         strbuf_addch(&buf, '/');
 199                 }
 200                 strbuf_addstr(&buf, file);
 201
 202                 if (is_executable(buf.buf))
 203                         return strbuf_detach(&buf, NULL);
 204
 205                 if (!*end)
 206                         break;
 207                 p = end + 1;
 208         }
 209
 210         strbuf_release(&buf);
 211         return NULL;
 212 }
 213
 214 static int exists_in_PATH(const char *file)
 215 {
 216         char *r = locate_in_PATH(file);
 217         int found = r != NULL;
 218         free(r);
 219         return found;
 220 }
 221
 222 int sane_execvp(const char *file, char * const argv[])
 223 {
 224 #ifndef GIT_WINDOWS_NATIVE
 225         /*
 226          * execvp() doesn't return, so we all we can do is tell trace2
 227          * what we are about to do and let it leave a hint in the log
 228          * (unless of course the execvp() fails).
 229          *
 230          * we skip this for Windows because the compat layer already
 231          * has to emulate the execvp() call anyway.
 232          */
 233         int exec_id = trace2_exec(file, (const char **)argv);
 234 #endif
 235
 236         if (!execvp(file, argv))
 237                 return 0; /* cannot happen ;-) */
 238
 239 #ifndef GIT_WINDOWS_NATIVE
 240         {
 241                 int ec = errno;
 242                 trace2_exec_result(exec_id, ec);
 243                 errno = ec;
 244         }
 245 #endif
 246
 247         /*
 248          * When a command can't be found because one of the directories
 249          * listed in $PATH is unsearchable, execvp reports EACCES, but
 250          * careful usability testing (read: analysis of occasional bug
 251          * reports) reveals that "No such file or directory" is more
 252          * intuitive.
 253          *
 254          * We avoid commands with "/", because execvp will not do $PATH
 255          * lookups in that case.
 256          *
 257          * The reassignment of EACCES to errno looks like a no-op below,
 258          * but we need to protect against exists_in_PATH overwriting errno.
 259          */
 260         if (errno == EACCES && !strchr(file, '/'))
 261                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
 262         else if (errno == ENOTDIR && !strchr(file, '/'))
 263                 errno = ENOENT;
 264         return -1;
 265 }
 266
 267 static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
 268 {
 269         if (!argv[0])
 270                 BUG("shell command is empty");
 271
 272         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 273 #ifndef GIT_WINDOWS_NATIVE
 274                 strvec_push(out, SHELL_PATH);
 275 #else
 276                 strvec_push(out, "sh");
 277 #endif
 278                 strvec_push(out, "-c");
 279
 280                 /*
 281                  * If we have no extra arguments, we do not even need to
 282                  * bother with the "$@" magic.
 283                  */
 284                 if (!argv[1])
 285                         strvec_push(out, argv[0]);
 286                 else
 287                         strvec_pushf(out, "%s \"$@\"", argv[0]);
 288         }
 289
 290         strvec_pushv(out, argv);
 291         return out->v;
 292 }
 293
 294 #ifndef GIT_WINDOWS_NATIVE
 295 static int child_notifier = -1;
 296
 297 enum child_errcode {
 298         CHILD_ERR_CHDIR,
 299         CHILD_ERR_DUP2,
 300         CHILD_ERR_CLOSE,
 301         CHILD_ERR_SIGPROCMASK,
 302         CHILD_ERR_ENOENT,
 303         CHILD_ERR_SILENT,
 304         CHILD_ERR_ERRNO
 305 };
 306
 307 struct child_err {
 308         enum child_errcode err;
 309         int syserr; /* errno */
 310 };
 311
 312 static void child_die(enum child_errcode err)
 313 {
 314         struct child_err buf;
 315
 316         buf.err = err;
 317         buf.syserr = errno;
 318
 319         /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 320         xwrite(child_notifier, &buf, sizeof(buf));
 321         _exit(1);
 322 }
 323
 324 static void child_dup2(int fd, int to)
 325 {
 326         if (dup2(fd, to) < 0)
 327                 child_die(CHILD_ERR_DUP2);
 328 }
 329
 330 static void child_close(int fd)
 331 {
 332         if (close(fd))
 333                 child_die(CHILD_ERR_CLOSE);
 334 }
 335
 336 static void child_close_pair(int fd[2])
 337 {
 338         child_close(fd[0]);
 339         child_close(fd[1]);
 340 }
 341
 342 /*
 343  * parent will make it look like the child spewed a fatal error and died
 344  * this is needed to prevent changes to t0061.
 345  */
 346 static void fake_fatal(const char *err, va_list params)
 347 {
 348         vreportf("fatal: ", err, params);
 349 }
 350
 351 static void child_error_fn(const char *err, va_list params)
 352 {
 353         const char msg[] = "error() should not be called in child\n";
 354         xwrite(2, msg, sizeof(msg) - 1);
 355 }
 356
 357 static void child_warn_fn(const char *err, va_list params)
 358 {
 359         const char msg[] = "warn() should not be called in child\n";
 360         xwrite(2, msg, sizeof(msg) - 1);
 361 }
 362
 363 static void NORETURN child_die_fn(const char *err, va_list params)
 364 {
 365         const char msg[] = "die() should not be called in child\n";
 366         xwrite(2, msg, sizeof(msg) - 1);
 367         _exit(2);
 368 }
 369
 370 /* this runs in the parent process */
 371 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 372 {
 373         static void (*old_errfn)(const char *err, va_list params);
 374
 375         old_errfn = get_error_routine();
 376         set_error_routine(fake_fatal);
 377         errno = cerr->syserr;
 378
 379         switch (cerr->err) {
 380         case CHILD_ERR_CHDIR:
 381                 error_errno("exec '%s': cd to '%s' failed",
 382                             cmd->argv[0], cmd->dir);
 383                 break;
 384         case CHILD_ERR_DUP2:
 385                 error_errno("dup2() in child failed");
 386                 break;
 387         case CHILD_ERR_CLOSE:
 388                 error_errno("close() in child failed");
 389                 break;
 390         case CHILD_ERR_SIGPROCMASK:
 391                 error_errno("sigprocmask failed restoring signals");
 392                 break;
 393         case CHILD_ERR_ENOENT:
 394                 error_errno("cannot run %s", cmd->argv[0]);
 395                 break;
 396         case CHILD_ERR_SILENT:
 397                 break;
 398         case CHILD_ERR_ERRNO:
 399                 error_errno("cannot exec '%s'", cmd->argv[0]);
 400                 break;
 401         }
 402         set_error_routine(old_errfn);
 403 }
 404
 405 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 406 {
 407         if (!cmd->argv[0])
 408                 BUG("command is empty");
 409
 410         /*
 411          * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 412          * attempt to interpret the command with 'sh'.
 413          */
 414         strvec_push(out, SHELL_PATH);
 415
 416         if (cmd->git_cmd) {
 417                 prepare_git_cmd(out, cmd->argv);
 418         } else if (cmd->use_shell) {
 419                 prepare_shell_cmd(out, cmd->argv);
 420         } else {
 421                 strvec_pushv(out, cmd->argv);
 422         }
 423
 424         /*
 425          * If there are no dir separator characters in the command then perform
 426          * a path lookup and use the resolved path as the command to exec. If
 427          * there are dir separator characters, we have exec attempt to invoke
 428          * the command directly.
 429          */
 430         if (!has_dir_sep(out->v[1])) {
 431                 char *program = locate_in_PATH(out->v[1]);
 432                 if (program) {
 433                         free((char *)out->v[1]);
 434                         out->v[1] = program;
 435                 } else {
 436                         strvec_clear(out);
 437                         errno = ENOENT;
 438                         return -1;
 439                 }
 440         }
 441
 442         return 0;
 443 }
 444
 445 static char **prep_childenv(const char *const *deltaenv)
 446 {
 447         extern char **environ;
 448         char **childenv;
 449         struct string_list env = STRING_LIST_INIT_DUP;
 450         struct strbuf key = STRBUF_INIT;
 451         const char *const *p;
 452         int i;
 453
 454         /* Construct a sorted string list consisting of the current environ */
 455         for (p = (const char *const *) environ; p && *p; p++) {
 456                 const char *equals = strchr(*p, '=');
 457
 458                 if (equals) {
 459                         strbuf_reset(&key);
 460                         strbuf_add(&key, *p, equals - *p);
 461                         string_list_append(&env, key.buf)->util = (void *) *p;
 462                 } else {
 463                         string_list_append(&env, *p)->util = (void *) *p;
 464                 }
 465         }
 466         string_list_sort(&env);
 467
 468         /* Merge in 'deltaenv' with the current environ */
 469         for (p = deltaenv; p && *p; p++) {
 470                 const char *equals = strchr(*p, '=');
 471
 472                 if (equals) {
 473                         /* ('key=value'), insert or replace entry */
 474                         strbuf_reset(&key);
 475                         strbuf_add(&key, *p, equals - *p);
 476                         string_list_insert(&env, key.buf)->util = (void *) *p;
 477                 } else {
 478                         /* otherwise ('key') remove existing entry */
 479                         string_list_remove(&env, *p, 0);
 480                 }
 481         }
 482
 483         /* Create an array of 'char *' to be used as the childenv */
 484         ALLOC_ARRAY(childenv, env.nr + 1);
 485         for (i = 0; i < env.nr; i++)
 486                 childenv[i] = env.items[i].util;
 487         childenv[env.nr] = NULL;
 488
 489         string_list_clear(&env, 0);
 490         strbuf_release(&key);
 491         return childenv;
 492 }
 493
 494 struct atfork_state {
 495 #ifndef NO_PTHREADS
 496         int cs;
 497 #endif
 498         sigset_t old;
 499 };
 500
 501 #define CHECK_BUG(err, msg) \
 502         do { \
 503                 int e = (err); \
 504                 if (e) \
 505                         BUG("%s: %s", msg, strerror(e)); \
 506         } while(0)
 507
 508 static void atfork_prepare(struct atfork_state *as)
 509 {
 510         sigset_t all;
 511
 512         if (sigfillset(&all))
 513                 die_errno("sigfillset");
 514 #ifdef NO_PTHREADS
 515         if (sigprocmask(SIG_SETMASK, &all, &as->old))
 516                 die_errno("sigprocmask");
 517 #else
 518         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 519                 "blocking all signals");
 520         CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 521                 "disabling cancellation");
 522 #endif
 523 }
 524
 525 static void atfork_parent(struct atfork_state *as)
 526 {
 527 #ifdef NO_PTHREADS
 528         if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 529                 die_errno("sigprocmask");
 530 #else
 531         CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 532                 "re-enabling cancellation");
 533         CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 534                 "restoring signal mask");
 535 #endif
 536 }
 537 #endif /* GIT_WINDOWS_NATIVE */
 538
 539 static inline void set_cloexec(int fd)
 540 {
 541         int flags = fcntl(fd, F_GETFD);
 542         if (flags >= 0)
 543                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 544 }
 545
 546 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 547 {
 548         int status, code = -1;
 549         pid_t waiting;
 550         int failed_errno = 0;
 551
 552         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 553                 ;       /* nothing */
 554         if (in_signal) {
 555                 if (WIFEXITED(status))
 556                         code = WEXITSTATUS(status);
 557                 return code;
 558         }
 559
 560         if (waiting < 0) {
 561                 failed_errno = errno;
 562                 error_errno("waitpid for %s failed", argv0);
 563         } else if (waiting != pid) {
 564                 error("waitpid is confused (%s)", argv0);
 565         } else if (WIFSIGNALED(status)) {
 566                 code = WTERMSIG(status);
 567                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 568                         error("%s died of signal %d", argv0, code);
 569                 /*
 570                  * This return value is chosen so that code & 0xff
 571                  * mimics the exit code that a POSIX shell would report for
 572                  * a program that died from this signal.
 573                  */
 574                 code += 128;
 575         } else if (WIFEXITED(status)) {
 576                 code = WEXITSTATUS(status);
 577         } else {
 578                 error("waitpid is confused (%s)", argv0);
 579         }
 580
 581         clear_child_for_cleanup(pid);
 582
 583         errno = failed_errno;
 584         return code;
 585 }
 586
 587 static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 588 {
 589         struct string_list envs = STRING_LIST_INIT_DUP;
 590         const char *const *e;
 591         int i;
 592         int printed_unset = 0;
 593
 594         /* Last one wins, see run-command.c:prep_childenv() for context */
 595         for (e = deltaenv; e && *e; e++) {
 596                 struct strbuf key = STRBUF_INIT;
 597                 char *equals = strchr(*e, '=');
 598
 599                 if (equals) {
 600                         strbuf_add(&key, *e, equals - *e);
 601                         string_list_insert(&envs, key.buf)->util = equals + 1;
 602                 } else {
 603                         string_list_insert(&envs, *e)->util = NULL;
 604                 }
 605                 strbuf_release(&key);
 606         }
 607
 608         /* "unset X Y...;" */
 609         for (i = 0; i < envs.nr; i++) {
 610                 const char *var = envs.items[i].string;
 611                 const char *val = envs.items[i].util;
 612
 613                 if (val || !getenv(var))
 614                         continue;
 615
 616                 if (!printed_unset) {
 617                         strbuf_addstr(dst, " unset");
 618                         printed_unset = 1;
 619                 }
 620                 strbuf_addf(dst, " %s", var);
 621         }
 622         if (printed_unset)
 623                 strbuf_addch(dst, ';');
 624
 625         /* ... followed by "A=B C=D ..." */
 626         for (i = 0; i < envs.nr; i++) {
 627                 const char *var = envs.items[i].string;
 628                 const char *val = envs.items[i].util;
 629                 const char *oldval;
 630
 631                 if (!val)
 632                         continue;
 633
 634                 oldval = getenv(var);
 635                 if (oldval && !strcmp(val, oldval))
 636                         continue;
 637
 638                 strbuf_addf(dst, " %s=", var);
 639                 sq_quote_buf_pretty(dst, val);
 640         }
 641         string_list_clear(&envs, 0);
 642 }
 643
 644 static void trace_run_command(const struct child_process *cp)
 645 {
 646         struct strbuf buf = STRBUF_INIT;
 647
 648         if (!trace_want(&trace_default_key))
 649                 return;
 650
 651         strbuf_addstr(&buf, "trace: run_command:");
 652         if (cp->dir) {
 653                 strbuf_addstr(&buf, " cd ");
 654                 sq_quote_buf_pretty(&buf, cp->dir);
 655                 strbuf_addch(&buf, ';');
 656         }
 657         /*
 658          * The caller is responsible for initializing cp->env from
 659          * cp->env_array if needed. We only check one place.
 660          */
 661         if (cp->env)
 662                 trace_add_env(&buf, cp->env);
 663         if (cp->git_cmd)
 664                 strbuf_addstr(&buf, " git");
 665         sq_quote_argv_pretty(&buf, cp->argv);
 666
 667         trace_printf("%s", buf.buf);
 668         strbuf_release(&buf);
 669 }
 670
 671 int start_command(struct child_process *cmd)
 672 {
 673         int need_in, need_out, need_err;
 674         int fdin[2], fdout[2], fderr[2];
 675         int failed_errno;
 676         char *str;
 677
 678         if (!cmd->argv)
 679                 cmd->argv = cmd->args.v;
 680         if (!cmd->env)
 681                 cmd->env = cmd->env_array.v;
 682
 683         /*
 684          * In case of errors we must keep the promise to close FDs
 685          * that have been passed in via ->in and ->out.
 686          */
 687
 688         need_in = !cmd->no_stdin && cmd->in < 0;
 689         if (need_in) {
 690                 if (pipe(fdin) < 0) {
 691                         failed_errno = errno;
 692                         if (cmd->out > 0)
 693                                 close(cmd->out);
 694                         str = "standard input";
 695                         goto fail_pipe;
 696                 }
 697                 cmd->in = fdin[1];
 698         }
 699
 700         need_out = !cmd->no_stdout
 701                 && !cmd->stdout_to_stderr
 702                 && cmd->out < 0;
 703         if (need_out) {
 704                 if (pipe(fdout) < 0) {
 705                         failed_errno = errno;
 706                         if (need_in)
 707                                 close_pair(fdin);
 708                         else if (cmd->in)
 709                                 close(cmd->in);
 710                         str = "standard output";
 711                         goto fail_pipe;
 712                 }
 713                 cmd->out = fdout[0];
 714         }
 715
 716         need_err = !cmd->no_stderr && cmd->err < 0;
 717         if (need_err) {
 718                 if (pipe(fderr) < 0) {
 719                         failed_errno = errno;
 720                         if (need_in)
 721                                 close_pair(fdin);
 722                         else if (cmd->in)
 723                                 close(cmd->in);
 724                         if (need_out)
 725                                 close_pair(fdout);
 726                         else if (cmd->out)
 727                                 close(cmd->out);
 728                         str = "standard error";
 729 fail_pipe:
 730                         error("cannot create %s pipe for %s: %s",
 731                                 str, cmd->argv[0], strerror(failed_errno));
 732                         child_process_clear(cmd);
 733                         errno = failed_errno;
 734                         return -1;
 735                 }
 736                 cmd->err = fderr[0];
 737         }
 738
 739         trace2_child_start(cmd);
 740         trace_run_command(cmd);
 741
 742         fflush(NULL);
 743
 744 #ifndef GIT_WINDOWS_NATIVE
 745 {
 746         int notify_pipe[2];
 747         int null_fd = -1;
 748         char **childenv;
 749         struct strvec argv = STRVEC_INIT;
 750         struct child_err cerr;
 751         struct atfork_state as;
 752
 753         if (prepare_cmd(&argv, cmd) < 0) {
 754                 failed_errno = errno;
 755                 cmd->pid = -1;
 756                 if (!cmd->silent_exec_failure)
 757                         error_errno("cannot run %s", cmd->argv[0]);
 758                 goto end_of_spawn;
 759         }
 760
 761         if (pipe(notify_pipe))
 762                 notify_pipe[0] = notify_pipe[1] = -1;
 763
 764         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 765                 null_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
 766                 if (null_fd < 0)
 767                         die_errno(_("open /dev/null failed"));
 768                 set_cloexec(null_fd);
 769         }
 770
 771         childenv = prep_childenv(cmd->env);
 772         atfork_prepare(&as);
 773
 774         /*
 775          * NOTE: In order to prevent deadlocking when using threads special
 776          * care should be taken with the function calls made in between the
 777          * fork() and exec() calls.  No calls should be made to functions which
 778          * require acquiring a lock (e.g. malloc) as the lock could have been
 779          * held by another thread at the time of forking, causing the lock to
 780          * never be released in the child process.  This means only
 781          * Async-Signal-Safe functions are permitted in the child.
 782          */
 783         cmd->pid = fork();
 784         failed_errno = errno;
 785         if (!cmd->pid) {
 786                 int sig;
 787                 /*
 788                  * Ensure the default die/error/warn routines do not get
 789                  * called, they can take stdio locks and malloc.
 790                  */
 791                 set_die_routine(child_die_fn);
 792                 set_error_routine(child_error_fn);
 793                 set_warn_routine(child_warn_fn);
 794
 795                 close(notify_pipe[0]);
 796                 set_cloexec(notify_pipe[1]);
 797                 child_notifier = notify_pipe[1];
 798
 799                 if (cmd->no_stdin)
 800                         child_dup2(null_fd, 0);
 801                 else if (need_in) {
 802                         child_dup2(fdin[0], 0);
 803                         child_close_pair(fdin);
 804                 } else if (cmd->in) {
 805                         child_dup2(cmd->in, 0);
 806                         child_close(cmd->in);
 807                 }
 808
 809                 if (cmd->no_stderr)
 810                         child_dup2(null_fd, 2);
 811                 else if (need_err) {
 812                         child_dup2(fderr[1], 2);
 813                         child_close_pair(fderr);
 814                 } else if (cmd->err > 1) {
 815                         child_dup2(cmd->err, 2);
 816                         child_close(cmd->err);
 817                 }
 818
 819                 if (cmd->no_stdout)
 820                         child_dup2(null_fd, 1);
 821                 else if (cmd->stdout_to_stderr)
 822                         child_dup2(2, 1);
 823                 else if (need_out) {
 824                         child_dup2(fdout[1], 1);
 825                         child_close_pair(fdout);
 826                 } else if (cmd->out > 1) {
 827                         child_dup2(cmd->out, 1);
 828                         child_close(cmd->out);
 829                 }
 830
 831                 if (cmd->dir && chdir(cmd->dir))
 832                         child_die(CHILD_ERR_CHDIR);
 833
 834                 /*
 835                  * restore default signal handlers here, in case
 836                  * we catch a signal right before execve below
 837                  */
 838                 for (sig = 1; sig < NSIG; sig++) {
 839                         /* ignored signals get reset to SIG_DFL on execve */
 840                         if (signal(sig, SIG_DFL) == SIG_IGN)
 841                                 signal(sig, SIG_IGN);
 842                 }
 843
 844                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 845                         child_die(CHILD_ERR_SIGPROCMASK);
 846
 847                 /*
 848                  * Attempt to exec using the command and arguments starting at
 849                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 850                  * be used in the event exec failed with ENOEXEC at which point
 851                  * we will try to interpret the command using 'sh'.
 852                  */
 853                 execve(argv.v[1], (char *const *) argv.v + 1,
 854                        (char *const *) childenv);
 855                 if (errno == ENOEXEC)
 856                         execve(argv.v[0], (char *const *) argv.v,
 857                                (char *const *) childenv);
 858
 859                 if (errno == ENOENT) {
 860                         if (cmd->silent_exec_failure)
 861                                 child_die(CHILD_ERR_SILENT);
 862                         child_die(CHILD_ERR_ENOENT);
 863                 } else {
 864                         child_die(CHILD_ERR_ERRNO);
 865                 }
 866         }
 867         atfork_parent(&as);
 868         if (cmd->pid < 0)
 869                 error_errno("cannot fork() for %s", cmd->argv[0]);
 870         else if (cmd->clean_on_exit)
 871                 mark_child_for_cleanup(cmd->pid, cmd);
 872
 873         /*
 874          * Wait for child's exec. If the exec succeeds (or if fork()
 875          * failed), EOF is seen immediately by the parent. Otherwise, the
 876          * child process sends a child_err struct.
 877          * Note that use of this infrastructure is completely advisory,
 878          * therefore, we keep error checks minimal.
 879          */
 880         close(notify_pipe[1]);
 881         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 882                 /*
 883                  * At this point we know that fork() succeeded, but exec()
 884                  * failed. Errors have been reported to our stderr.
 885                  */
 886                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 887                 child_err_spew(cmd, &cerr);
 888                 failed_errno = errno;
 889                 cmd->pid = -1;
 890         }
 891         close(notify_pipe[0]);
 892
 893         if (null_fd >= 0)
 894                 close(null_fd);
 895         strvec_clear(&argv);
 896         free(childenv);
 897 }
 898 end_of_spawn:
 899
 900 #else
 901 {
 902         int fhin = 0, fhout = 1, fherr = 2;
 903         const char **sargv = cmd->argv;
 904         struct strvec nargv = STRVEC_INIT;
 905
 906         if (cmd->no_stdin)
 907                 fhin = open("/dev/null", O_RDWR);
 908         else if (need_in)
 909                 fhin = dup(fdin[0]);
 910         else if (cmd->in)
 911                 fhin = dup(cmd->in);
 912
 913         if (cmd->no_stderr)
 914                 fherr = open("/dev/null", O_RDWR);
 915         else if (need_err)
 916                 fherr = dup(fderr[1]);
 917         else if (cmd->err > 2)
 918                 fherr = dup(cmd->err);
 919
 920         if (cmd->no_stdout)
 921                 fhout = open("/dev/null", O_RDWR);
 922         else if (cmd->stdout_to_stderr)
 923                 fhout = dup(fherr);
 924         else if (need_out)
 925                 fhout = dup(fdout[1]);
 926         else if (cmd->out > 1)
 927                 fhout = dup(cmd->out);
 928
 929         if (cmd->git_cmd)
 930                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 931         else if (cmd->use_shell)
 932                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 933
 934         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 935                         cmd->dir, fhin, fhout, fherr);
 936         failed_errno = errno;
 937         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 938                 error_errno("cannot spawn %s", cmd->argv[0]);
 939         if (cmd->clean_on_exit && cmd->pid >= 0)
 940                 mark_child_for_cleanup(cmd->pid, cmd);
 941
 942         strvec_clear(&nargv);
 943         cmd->argv = sargv;
 944         if (fhin != 0)
 945                 close(fhin);
 946         if (fhout != 1)
 947                 close(fhout);
 948         if (fherr != 2)
 949                 close(fherr);
 950 }
 951 #endif
 952
 953         if (cmd->pid < 0) {
 954                 trace2_child_exit(cmd, -1);
 955
 956                 if (need_in)
 957                         close_pair(fdin);
 958                 else if (cmd->in)
 959                         close(cmd->in);
 960                 if (need_out)
 961                         close_pair(fdout);
 962                 else if (cmd->out)
 963                         close(cmd->out);
 964                 if (need_err)
 965                         close_pair(fderr);
 966                 else if (cmd->err)
 967                         close(cmd->err);
 968                 child_process_clear(cmd);
 969                 errno = failed_errno;
 970                 return -1;
 971         }
 972
 973         if (need_in)
 974                 close(fdin[0]);
 975         else if (cmd->in)
 976                 close(cmd->in);
 977
 978         if (need_out)
 979                 close(fdout[1]);
 980         else if (cmd->out)
 981                 close(cmd->out);
 982
 983         if (need_err)
 984                 close(fderr[1]);
 985         else if (cmd->err)
 986                 close(cmd->err);
 987
 988         return 0;
 989 }
 990
 991 int finish_command(struct child_process *cmd)
 992 {
 993         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 994         trace2_child_exit(cmd, ret);
 995         child_process_clear(cmd);
 996         invalidate_lstat_cache();
 997         return ret;
 998 }
 999
1000 int finish_command_in_signal(struct child_process *cmd)
1001 {
1002         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
1003         trace2_child_exit(cmd, ret);
1004         return ret;
1005 }
1006
1007
1008 int run_command(struct child_process *cmd)
1009 {
1010         int code;
1011
1012         if (cmd->out < 0 || cmd->err < 0)
1013                 BUG("run_command with a pipe can cause deadlock");
1014
1015         code = start_command(cmd);
1016         if (code)
1017                 return code;
1018         return finish_command(cmd);
1019 }
1020
1021 int run_command_v_opt(const char **argv, int opt)
1022 {
1023         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
1024 }
1025
1026 int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
1027 {
1028         return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
1029 }
1030
1031 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
1032 {
1033         return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
1034 }
1035
1036 int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
1037                                  const char *const *env, const char *tr2_class)
1038 {
1039         struct child_process cmd = CHILD_PROCESS_INIT;
1040         cmd.argv = argv;
1041         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
1042         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
1043         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
1044         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
1045         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
1046         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
1047         cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
1048         cmd.dir = dir;
1049         cmd.env = env;
1050         cmd.trace2_child_class = tr2_class;
1051         return run_command(&cmd);
1052 }
1053
1054 #ifndef NO_PTHREADS
1055 static pthread_t main_thread;
1056 static int main_thread_set;
1057 static pthread_key_t async_key;
1058 static pthread_key_t async_die_counter;
1059
1060 static void *run_thread(void *data)
1061 {
1062         struct async *async = data;
1063         intptr_t ret;
1064
1065         if (async->isolate_sigpipe) {
1066                 sigset_t mask;
1067                 sigemptyset(&mask);
1068                 sigaddset(&mask, SIGPIPE);
1069                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
1070                         ret = error("unable to block SIGPIPE in async thread");
1071                         return (void *)ret;
1072                 }
1073         }
1074
1075         pthread_setspecific(async_key, async);
1076         ret = async->proc(async->proc_in, async->proc_out, async->data);
1077         return (void *)ret;
1078 }
1079
1080 static NORETURN void die_async(const char *err, va_list params)
1081 {
1082         vreportf("fatal: ", err, params);
1083
1084         if (in_async()) {
1085                 struct async *async = pthread_getspecific(async_key);
1086                 if (async->proc_in >= 0)
1087                         close(async->proc_in);
1088                 if (async->proc_out >= 0)
1089                         close(async->proc_out);
1090                 pthread_exit((void *)128);
1091         }
1092
1093         exit(128);
1094 }
1095
1096 static int async_die_is_recursing(void)
1097 {
1098         void *ret = pthread_getspecific(async_die_counter);
1099         pthread_setspecific(async_die_counter, (void *)1);
1100         return ret != NULL;
1101 }
1102
1103 int in_async(void)
1104 {
1105         if (!main_thread_set)
1106                 return 0; /* no asyncs started yet */
1107         return !pthread_equal(main_thread, pthread_self());
1108 }
1109
1110 static void NORETURN async_exit(int code)
1111 {
1112         pthread_exit((void *)(intptr_t)code);
1113 }
1114
1115 #else
1116
1117 static struct {
1118         void (**handlers)(void);
1119         size_t nr;
1120         size_t alloc;
1121 } git_atexit_hdlrs;
1122
1123 static int git_atexit_installed;
1124
1125 static void git_atexit_dispatch(void)
1126 {
1127         size_t i;
1128
1129         for (i=git_atexit_hdlrs.nr ; i ; i--)
1130                 git_atexit_hdlrs.handlers[i-1]();
1131 }
1132
1133 static void git_atexit_clear(void)
1134 {
1135         free(git_atexit_hdlrs.handlers);
1136         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1137         git_atexit_installed = 0;
1138 }
1139
1140 #undef atexit
1141 int git_atexit(void (*handler)(void))
1142 {
1143         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1144         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1145         if (!git_atexit_installed) {
1146                 if (atexit(&git_atexit_dispatch))
1147                         return -1;
1148                 git_atexit_installed = 1;
1149         }
1150         return 0;
1151 }
1152 #define atexit git_atexit
1153
1154 static int process_is_async;
1155 int in_async(void)
1156 {
1157         return process_is_async;
1158 }
1159
1160 static void NORETURN async_exit(int code)
1161 {
1162         exit(code);
1163 }
1164
1165 #endif
1166
1167 void check_pipe(int err)
1168 {
1169         if (err == EPIPE) {
1170                 if (in_async())
1171                         async_exit(141);
1172
1173                 signal(SIGPIPE, SIG_DFL);
1174                 raise(SIGPIPE);
1175                 /* Should never happen, but just in case... */
1176                 exit(141);
1177         }
1178 }
1179
1180 int start_async(struct async *async)
1181 {
1182         int need_in, need_out;
1183         int fdin[2], fdout[2];
1184         int proc_in, proc_out;
1185
1186         need_in = async->in < 0;
1187         if (need_in) {
1188                 if (pipe(fdin) < 0) {
1189                         if (async->out > 0)
1190                                 close(async->out);
1191                         return error_errno("cannot create pipe");
1192                 }
1193                 async->in = fdin[1];
1194         }
1195
1196         need_out = async->out < 0;
1197         if (need_out) {
1198                 if (pipe(fdout) < 0) {
1199                         if (need_in)
1200                                 close_pair(fdin);
1201                         else if (async->in)
1202                                 close(async->in);
1203                         return error_errno("cannot create pipe");
1204                 }
1205                 async->out = fdout[0];
1206         }
1207
1208         if (need_in)
1209                 proc_in = fdin[0];
1210         else if (async->in)
1211                 proc_in = async->in;
1212         else
1213                 proc_in = -1;
1214
1215         if (need_out)
1216                 proc_out = fdout[1];
1217         else if (async->out)
1218                 proc_out = async->out;
1219         else
1220                 proc_out = -1;
1221
1222 #ifdef NO_PTHREADS
1223         /* Flush stdio before fork() to avoid cloning buffers */
1224         fflush(NULL);
1225
1226         async->pid = fork();
1227         if (async->pid < 0) {
1228                 error_errno("fork (async) failed");
1229                 goto error;
1230         }
1231         if (!async->pid) {
1232                 if (need_in)
1233                         close(fdin[1]);
1234                 if (need_out)
1235                         close(fdout[0]);
1236                 git_atexit_clear();
1237                 process_is_async = 1;
1238                 exit(!!async->proc(proc_in, proc_out, async->data));
1239         }
1240
1241         mark_child_for_cleanup(async->pid, NULL);
1242
1243         if (need_in)
1244                 close(fdin[0]);
1245         else if (async->in)
1246                 close(async->in);
1247
1248         if (need_out)
1249                 close(fdout[1]);
1250         else if (async->out)
1251                 close(async->out);
1252 #else
1253         if (!main_thread_set) {
1254                 /*
1255                  * We assume that the first time that start_async is called
1256                  * it is from the main thread.
1257                  */
1258                 main_thread_set = 1;
1259                 main_thread = pthread_self();
1260                 pthread_key_create(&async_key, NULL);
1261                 pthread_key_create(&async_die_counter, NULL);
1262                 set_die_routine(die_async);
1263                 set_die_is_recursing_routine(async_die_is_recursing);
1264         }
1265
1266         if (proc_in >= 0)
1267                 set_cloexec(proc_in);
1268         if (proc_out >= 0)
1269                 set_cloexec(proc_out);
1270         async->proc_in = proc_in;
1271         async->proc_out = proc_out;
1272         {
1273                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1274                 if (err) {
1275                         error(_("cannot create async thread: %s"), strerror(err));
1276                         goto error;
1277                 }
1278         }
1279 #endif
1280         return 0;
1281
1282 error:
1283         if (need_in)
1284                 close_pair(fdin);
1285         else if (async->in)
1286                 close(async->in);
1287
1288         if (need_out)
1289                 close_pair(fdout);
1290         else if (async->out)
1291                 close(async->out);
1292         return -1;
1293 }
1294
1295 int finish_async(struct async *async)
1296 {
1297 #ifdef NO_PTHREADS
1298         int ret = wait_or_whine(async->pid, "child process", 0);
1299
1300         invalidate_lstat_cache();
1301
1302         return ret;
1303 #else
1304         void *ret = (void *)(intptr_t)(-1);
1305
1306         if (pthread_join(async->tid, &ret))
1307                 error("pthread_join failed");
1308         invalidate_lstat_cache();
1309         return (int)(intptr_t)ret;
1310
1311 #endif
1312 }
1313
1314 int async_with_fork(void)
1315 {
1316 #ifdef NO_PTHREADS
1317         return 1;
1318 #else
1319         return 0;
1320 #endif
1321 }
1322
1323 const char *find_hook(const char *name)
1324 {
1325         static struct strbuf path = STRBUF_INIT;
1326
1327         strbuf_reset(&path);
1328         strbuf_git_path(&path, "hooks/%s", name);
1329         if (access(path.buf, X_OK) < 0) {
1330                 int err = errno;
1331
1332 #ifdef STRIP_EXTENSION
1333                 strbuf_addstr(&path, STRIP_EXTENSION);
1334                 if (access(path.buf, X_OK) >= 0)
1335                         return path.buf;
1336                 if (errno == EACCES)
1337                         err = errno;
1338 #endif
1339
1340                 if (err == EACCES && advice_ignored_hook) {
1341                         static struct string_list advise_given = STRING_LIST_INIT_DUP;
1342
1343                         if (!string_list_lookup(&advise_given, name)) {
1344                                 string_list_insert(&advise_given, name);
1345                                 advise(_("The '%s' hook was ignored because "
1346                                          "it's not set as executable.\n"
1347                                          "You can disable this warning with "
1348                                          "`git config advice.ignoredHook false`."),
1349                                        path.buf);
1350                         }
1351                 }
1352                 return NULL;
1353         }
1354         return path.buf;
1355 }
1356
1357 int run_hook_ve(const char *const *env, const char *name, va_list args)
1358 {
1359         struct child_process hook = CHILD_PROCESS_INIT;
1360         const char *p;
1361
1362         p = find_hook(name);
1363         if (!p)
1364                 return 0;
1365
1366         strvec_push(&hook.args, p);
1367         while ((p = va_arg(args, const char *)))
1368                 strvec_push(&hook.args, p);
1369         hook.env = env;
1370         hook.no_stdin = 1;
1371         hook.stdout_to_stderr = 1;
1372         hook.trace2_hook_name = name;
1373
1374         return run_command(&hook);
1375 }
1376
1377 int run_hook_le(const char *const *env, const char *name, ...)
1378 {
1379         va_list args;
1380         int ret;
1381
1382         va_start(args, name);
1383         ret = run_hook_ve(env, name, args);
1384         va_end(args);
1385
1386         return ret;
1387 }
1388
1389 struct io_pump {
1390         /* initialized by caller */
1391         int fd;
1392         int type; /* POLLOUT or POLLIN */
1393         union {
1394                 struct {
1395                         const char *buf;
1396                         size_t len;
1397                 } out;
1398                 struct {
1399                         struct strbuf *buf;
1400                         size_t hint;
1401                 } in;
1402         } u;
1403
1404         /* returned by pump_io */
1405         int error; /* 0 for success, otherwise errno */
1406
1407         /* internal use */
1408         struct pollfd *pfd;
1409 };
1410
1411 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1412 {
1413         int pollsize = 0;
1414         int i;
1415
1416         for (i = 0; i < nr; i++) {
1417                 struct io_pump *io = &slots[i];
1418                 if (io->fd < 0)
1419                         continue;
1420                 pfd[pollsize].fd = io->fd;
1421                 pfd[pollsize].events = io->type;
1422                 io->pfd = &pfd[pollsize++];
1423         }
1424
1425         if (!pollsize)
1426                 return 0;
1427
1428         if (poll(pfd, pollsize, -1) < 0) {
1429                 if (errno == EINTR)
1430                         return 1;
1431                 die_errno("poll failed");
1432         }
1433
1434         for (i = 0; i < nr; i++) {
1435                 struct io_pump *io = &slots[i];
1436
1437                 if (io->fd < 0)
1438                         continue;
1439
1440                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1441                         continue;
1442
1443                 if (io->type == POLLOUT) {
1444                         ssize_t len = xwrite(io->fd,
1445                                              io->u.out.buf, io->u.out.len);
1446                         if (len < 0) {
1447                                 io->error = errno;
1448                                 close(io->fd);
1449                                 io->fd = -1;
1450                         } else {
1451                                 io->u.out.buf += len;
1452                                 io->u.out.len -= len;
1453                                 if (!io->u.out.len) {
1454                                         close(io->fd);
1455                                         io->fd = -1;
1456                                 }
1457                         }
1458                 }
1459
1460                 if (io->type == POLLIN) {
1461                         ssize_t len = strbuf_read_once(io->u.in.buf,
1462                                                        io->fd, io->u.in.hint);
1463                         if (len < 0)
1464                                 io->error = errno;
1465                         if (len <= 0) {
1466                                 close(io->fd);
1467                                 io->fd = -1;
1468                         }
1469                 }
1470         }
1471
1472         return 1;
1473 }
1474
1475 static int pump_io(struct io_pump *slots, int nr)
1476 {
1477         struct pollfd *pfd;
1478         int i;
1479
1480         for (i = 0; i < nr; i++)
1481                 slots[i].error = 0;
1482
1483         ALLOC_ARRAY(pfd, nr);
1484         while (pump_io_round(slots, nr, pfd))
1485                 ; /* nothing */
1486         free(pfd);
1487
1488         /* There may be multiple errno values, so just pick the first. */
1489         for (i = 0; i < nr; i++) {
1490                 if (slots[i].error) {
1491                         errno = slots[i].error;
1492                         return -1;
1493                 }
1494         }
1495         return 0;
1496 }
1497
1498
1499 int pipe_command(struct child_process *cmd,
1500                  const char *in, size_t in_len,
1501                  struct strbuf *out, size_t out_hint,
1502                  struct strbuf *err, size_t err_hint)
1503 {
1504         struct io_pump io[3];
1505         int nr = 0;
1506
1507         if (in)
1508                 cmd->in = -1;
1509         if (out)
1510                 cmd->out = -1;
1511         if (err)
1512                 cmd->err = -1;
1513
1514         if (start_command(cmd) < 0)
1515                 return -1;
1516
1517         if (in) {
1518                 io[nr].fd = cmd->in;
1519                 io[nr].type = POLLOUT;
1520                 io[nr].u.out.buf = in;
1521                 io[nr].u.out.len = in_len;
1522                 nr++;
1523         }
1524         if (out) {
1525                 io[nr].fd = cmd->out;
1526                 io[nr].type = POLLIN;
1527                 io[nr].u.in.buf = out;
1528                 io[nr].u.in.hint = out_hint;
1529                 nr++;
1530         }
1531         if (err) {
1532                 io[nr].fd = cmd->err;
1533                 io[nr].type = POLLIN;
1534                 io[nr].u.in.buf = err;
1535                 io[nr].u.in.hint = err_hint;
1536                 nr++;
1537         }
1538
1539         if (pump_io(io, nr) < 0) {
1540                 finish_command(cmd); /* throw away exit code */
1541                 return -1;
1542         }
1543
1544         return finish_command(cmd);
1545 }
1546
1547 enum child_state {
1548         GIT_CP_FREE,
1549         GIT_CP_WORKING,
1550         GIT_CP_WAIT_CLEANUP,
1551 };
1552
1553 struct parallel_processes {
1554         void *data;
1555
1556         int max_processes;
1557         int nr_processes;
1558
1559         get_next_task_fn get_next_task;
1560         start_failure_fn start_failure;
1561         task_finished_fn task_finished;
1562
1563         struct {
1564                 enum child_state state;
1565                 struct child_process process;
1566                 struct strbuf err;
1567                 void *data;
1568         } *children;
1569         /*
1570          * The struct pollfd is logically part of *children,
1571          * but the system call expects it as its own array.
1572          */
1573         struct pollfd *pfd;
1574
1575         unsigned shutdown : 1;
1576
1577         int output_owner;
1578         struct strbuf buffered_output; /* of finished children */
1579 };
1580
1581 static int default_start_failure(struct strbuf *out,
1582                                  void *pp_cb,
1583                                  void *pp_task_cb)
1584 {
1585         return 0;
1586 }
1587
1588 static int default_task_finished(int result,
1589                                  struct strbuf *out,
1590                                  void *pp_cb,
1591                                  void *pp_task_cb)
1592 {
1593         return 0;
1594 }
1595
1596 static void kill_children(struct parallel_processes *pp, int signo)
1597 {
1598         int i, n = pp->max_processes;
1599
1600         for (i = 0; i < n; i++)
1601                 if (pp->children[i].state == GIT_CP_WORKING)
1602                         kill(pp->children[i].process.pid, signo);
1603 }
1604
1605 static struct parallel_processes *pp_for_signal;
1606
1607 static void handle_children_on_signal(int signo)
1608 {
1609         kill_children(pp_for_signal, signo);
1610         sigchain_pop(signo);
1611         raise(signo);
1612 }
1613
1614 static void pp_init(struct parallel_processes *pp,
1615                     int n,
1616                     get_next_task_fn get_next_task,
1617                     start_failure_fn start_failure,
1618                     task_finished_fn task_finished,
1619                     void *data)
1620 {
1621         int i;
1622
1623         if (n < 1)
1624                 n = online_cpus();
1625
1626         pp->max_processes = n;
1627
1628         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1629
1630         pp->data = data;
1631         if (!get_next_task)
1632                 BUG("you need to specify a get_next_task function");
1633         pp->get_next_task = get_next_task;
1634
1635         pp->start_failure = start_failure ? start_failure : default_start_failure;
1636         pp->task_finished = task_finished ? task_finished : default_task_finished;
1637
1638         pp->nr_processes = 0;
1639         pp->output_owner = 0;
1640         pp->shutdown = 0;
1641         pp->children = xcalloc(n, sizeof(*pp->children));
1642         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1643         strbuf_init(&pp->buffered_output, 0);
1644
1645         for (i = 0; i < n; i++) {
1646                 strbuf_init(&pp->children[i].err, 0);
1647                 child_process_init(&pp->children[i].process);
1648                 pp->pfd[i].events = POLLIN | POLLHUP;
1649                 pp->pfd[i].fd = -1;
1650         }
1651
1652         pp_for_signal = pp;
1653         sigchain_push_common(handle_children_on_signal);
1654 }
1655
1656 static void pp_cleanup(struct parallel_processes *pp)
1657 {
1658         int i;
1659
1660         trace_printf("run_processes_parallel: done");
1661         for (i = 0; i < pp->max_processes; i++) {
1662                 strbuf_release(&pp->children[i].err);
1663                 child_process_clear(&pp->children[i].process);
1664         }
1665
1666         free(pp->children);
1667         free(pp->pfd);
1668
1669         /*
1670          * When get_next_task added messages to the buffer in its last
1671          * iteration, the buffered output is non empty.
1672          */
1673         strbuf_write(&pp->buffered_output, stderr);
1674         strbuf_release(&pp->buffered_output);
1675
1676         sigchain_pop_common();
1677 }
1678
1679 /* returns
1680  *  0 if a new task was started.
1681  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1682  *    problem with starting a new command)
1683  * <0 no new job was started, user wishes to shutdown early. Use negative code
1684  *    to signal the children.
1685  */
1686 static int pp_start_one(struct parallel_processes *pp)
1687 {
1688         int i, code;
1689
1690         for (i = 0; i < pp->max_processes; i++)
1691                 if (pp->children[i].state == GIT_CP_FREE)
1692                         break;
1693         if (i == pp->max_processes)
1694                 BUG("bookkeeping is hard");
1695
1696         code = pp->get_next_task(&pp->children[i].process,
1697                                  &pp->children[i].err,
1698                                  pp->data,
1699                                  &pp->children[i].data);
1700         if (!code) {
1701                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1702                 strbuf_reset(&pp->children[i].err);
1703                 return 1;
1704         }
1705         pp->children[i].process.err = -1;
1706         pp->children[i].process.stdout_to_stderr = 1;
1707         pp->children[i].process.no_stdin = 1;
1708
1709         if (start_command(&pp->children[i].process)) {
1710                 code = pp->start_failure(&pp->children[i].err,
1711                                          pp->data,
1712                                          pp->children[i].data);
1713                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1714                 strbuf_reset(&pp->children[i].err);
1715                 if (code)
1716                         pp->shutdown = 1;
1717                 return code;
1718         }
1719
1720         pp->nr_processes++;
1721         pp->children[i].state = GIT_CP_WORKING;
1722         pp->pfd[i].fd = pp->children[i].process.err;
1723         return 0;
1724 }
1725
1726 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1727 {
1728         int i;
1729
1730         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1731                 if (errno == EINTR)
1732                         continue;
1733                 pp_cleanup(pp);
1734                 die_errno("poll");
1735         }
1736
1737         /* Buffer output from all pipes. */
1738         for (i = 0; i < pp->max_processes; i++) {
1739                 if (pp->children[i].state == GIT_CP_WORKING &&
1740                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1741                         int n = strbuf_read_once(&pp->children[i].err,
1742                                                  pp->children[i].process.err, 0);
1743                         if (n == 0) {
1744                                 close(pp->children[i].process.err);
1745                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1746                         } else if (n < 0)
1747                                 if (errno != EAGAIN)
1748                                         die_errno("read");
1749                 }
1750         }
1751 }
1752
1753 static void pp_output(struct parallel_processes *pp)
1754 {
1755         int i = pp->output_owner;
1756         if (pp->children[i].state == GIT_CP_WORKING &&
1757             pp->children[i].err.len) {
1758                 strbuf_write(&pp->children[i].err, stderr);
1759                 strbuf_reset(&pp->children[i].err);
1760         }
1761 }
1762
1763 static int pp_collect_finished(struct parallel_processes *pp)
1764 {
1765         int i, code;
1766         int n = pp->max_processes;
1767         int result = 0;
1768
1769         while (pp->nr_processes > 0) {
1770                 for (i = 0; i < pp->max_processes; i++)
1771                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1772                                 break;
1773                 if (i == pp->max_processes)
1774                         break;
1775
1776                 code = finish_command(&pp->children[i].process);
1777
1778                 code = pp->task_finished(code,
1779                                          &pp->children[i].err, pp->data,
1780                                          pp->children[i].data);
1781
1782                 if (code)
1783                         result = code;
1784                 if (code < 0)
1785                         break;
1786
1787                 pp->nr_processes--;
1788                 pp->children[i].state = GIT_CP_FREE;
1789                 pp->pfd[i].fd = -1;
1790                 child_process_init(&pp->children[i].process);
1791
1792                 if (i != pp->output_owner) {
1793                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1794                         strbuf_reset(&pp->children[i].err);
1795                 } else {
1796                         strbuf_write(&pp->children[i].err, stderr);
1797                         strbuf_reset(&pp->children[i].err);
1798
1799                         /* Output all other finished child processes */
1800                         strbuf_write(&pp->buffered_output, stderr);
1801                         strbuf_reset(&pp->buffered_output);
1802
1803                         /*
1804                          * Pick next process to output live.
1805                          * NEEDSWORK:
1806                          * For now we pick it randomly by doing a round
1807                          * robin. Later we may want to pick the one with
1808                          * the most output or the longest or shortest
1809                          * running process time.
1810                          */
1811                         for (i = 0; i < n; i++)
1812                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1813                                         break;
1814                         pp->output_owner = (pp->output_owner + i) % n;
1815                 }
1816         }
1817         return result;
1818 }
1819
1820 int run_processes_parallel(int n,
1821                            get_next_task_fn get_next_task,
1822                            start_failure_fn start_failure,
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         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1832         while (1) {
1833                 for (i = 0;
1834                     i < spawn_cap && !pp.shutdown &&
1835                     pp.nr_processes < pp.max_processes;
1836                     i++) {
1837                         code = pp_start_one(&pp);
1838                         if (!code)
1839                                 continue;
1840                         if (code < 0) {
1841                                 pp.shutdown = 1;
1842                                 kill_children(&pp, -code);
1843                         }
1844                         break;
1845                 }
1846                 if (!pp.nr_processes)
1847                         break;
1848                 pp_buffer_stderr(&pp, output_timeout);
1849                 pp_output(&pp);
1850                 code = pp_collect_finished(&pp);
1851                 if (code) {
1852                         pp.shutdown = 1;
1853                         if (code < 0)
1854                                 kill_children(&pp, -code);
1855                 }
1856         }
1857
1858         pp_cleanup(&pp);
1859         return 0;
1860 }
1861
1862 int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
1863                                start_failure_fn start_failure,
1864                                task_finished_fn task_finished, void *pp_cb,
1865                                const char *tr2_category, const char *tr2_label)
1866 {
1867         int result;
1868
1869         trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
1870                                    ((n < 1) ? online_cpus() : n));
1871
1872         result = run_processes_parallel(n, get_next_task, start_failure,
1873                                         task_finished, pp_cb);
1874
1875         trace2_region_leave(tr2_category, tr2_label, NULL);
1876
1877         return result;
1878 }
1879
1880 int run_auto_maintenance(int quiet)
1881 {
1882         int enabled;
1883         struct child_process maint = CHILD_PROCESS_INIT;
1884
1885         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1886             !enabled)
1887                 return 0;
1888
1889         maint.git_cmd = 1;
1890         strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
1891         strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
1892
1893         return run_command(&maint);
1894 }