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 "packfile.h"
  12 #include "hook.h"
  13
  14 void child_process_init(struct child_process *child)
  15 {
  16         struct child_process blank = CHILD_PROCESS_INIT;
  17         memcpy(child, &blank, sizeof(*child));
  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 int exists_in_PATH(const char *command)
 216 {
 217         char *r = locate_in_PATH(command);
 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         if (cmd->close_object_store)
 746                 close_object_store(the_repository->objects);
 747
 748 #ifndef GIT_WINDOWS_NATIVE
 749 {
 750         int notify_pipe[2];
 751         int null_fd = -1;
 752         char **childenv;
 753         struct strvec argv = STRVEC_INIT;
 754         struct child_err cerr;
 755         struct atfork_state as;
 756
 757         if (prepare_cmd(&argv, cmd) < 0) {
 758                 failed_errno = errno;
 759                 cmd->pid = -1;
 760                 if (!cmd->silent_exec_failure)
 761                         error_errno("cannot run %s", cmd->argv[0]);
 762                 goto end_of_spawn;
 763         }
 764
 765         if (pipe(notify_pipe))
 766                 notify_pipe[0] = notify_pipe[1] = -1;
 767
 768         if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 769                 null_fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
 770                 set_cloexec(null_fd);
 771         }
 772
 773         childenv = prep_childenv(cmd->env);
 774         atfork_prepare(&as);
 775
 776         /*
 777          * NOTE: In order to prevent deadlocking when using threads special
 778          * care should be taken with the function calls made in between the
 779          * fork() and exec() calls.  No calls should be made to functions which
 780          * require acquiring a lock (e.g. malloc) as the lock could have been
 781          * held by another thread at the time of forking, causing the lock to
 782          * never be released in the child process.  This means only
 783          * Async-Signal-Safe functions are permitted in the child.
 784          */
 785         cmd->pid = fork();
 786         failed_errno = errno;
 787         if (!cmd->pid) {
 788                 int sig;
 789                 /*
 790                  * Ensure the default die/error/warn routines do not get
 791                  * called, they can take stdio locks and malloc.
 792                  */
 793                 set_die_routine(child_die_fn);
 794                 set_error_routine(child_error_fn);
 795                 set_warn_routine(child_warn_fn);
 796
 797                 close(notify_pipe[0]);
 798                 set_cloexec(notify_pipe[1]);
 799                 child_notifier = notify_pipe[1];
 800
 801                 if (cmd->no_stdin)
 802                         child_dup2(null_fd, 0);
 803                 else if (need_in) {
 804                         child_dup2(fdin[0], 0);
 805                         child_close_pair(fdin);
 806                 } else if (cmd->in) {
 807                         child_dup2(cmd->in, 0);
 808                         child_close(cmd->in);
 809                 }
 810
 811                 if (cmd->no_stderr)
 812                         child_dup2(null_fd, 2);
 813                 else if (need_err) {
 814                         child_dup2(fderr[1], 2);
 815                         child_close_pair(fderr);
 816                 } else if (cmd->err > 1) {
 817                         child_dup2(cmd->err, 2);
 818                         child_close(cmd->err);
 819                 }
 820
 821                 if (cmd->no_stdout)
 822                         child_dup2(null_fd, 1);
 823                 else if (cmd->stdout_to_stderr)
 824                         child_dup2(2, 1);
 825                 else if (need_out) {
 826                         child_dup2(fdout[1], 1);
 827                         child_close_pair(fdout);
 828                 } else if (cmd->out > 1) {
 829                         child_dup2(cmd->out, 1);
 830                         child_close(cmd->out);
 831                 }
 832
 833                 if (cmd->dir && chdir(cmd->dir))
 834                         child_die(CHILD_ERR_CHDIR);
 835
 836                 /*
 837                  * restore default signal handlers here, in case
 838                  * we catch a signal right before execve below
 839                  */
 840                 for (sig = 1; sig < NSIG; sig++) {
 841                         /* ignored signals get reset to SIG_DFL on execve */
 842                         if (signal(sig, SIG_DFL) == SIG_IGN)
 843                                 signal(sig, SIG_IGN);
 844                 }
 845
 846                 if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 847                         child_die(CHILD_ERR_SIGPROCMASK);
 848
 849                 /*
 850                  * Attempt to exec using the command and arguments starting at
 851                  * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 852                  * be used in the event exec failed with ENOEXEC at which point
 853                  * we will try to interpret the command using 'sh'.
 854                  */
 855                 execve(argv.v[1], (char *const *) argv.v + 1,
 856                        (char *const *) childenv);
 857                 if (errno == ENOEXEC)
 858                         execve(argv.v[0], (char *const *) argv.v,
 859                                (char *const *) childenv);
 860
 861                 if (errno == ENOENT) {
 862                         if (cmd->silent_exec_failure)
 863                                 child_die(CHILD_ERR_SILENT);
 864                         child_die(CHILD_ERR_ENOENT);
 865                 } else {
 866                         child_die(CHILD_ERR_ERRNO);
 867                 }
 868         }
 869         atfork_parent(&as);
 870         if (cmd->pid < 0)
 871                 error_errno("cannot fork() for %s", cmd->argv[0]);
 872         else if (cmd->clean_on_exit)
 873                 mark_child_for_cleanup(cmd->pid, cmd);
 874
 875         /*
 876          * Wait for child's exec. If the exec succeeds (or if fork()
 877          * failed), EOF is seen immediately by the parent. Otherwise, the
 878          * child process sends a child_err struct.
 879          * Note that use of this infrastructure is completely advisory,
 880          * therefore, we keep error checks minimal.
 881          */
 882         close(notify_pipe[1]);
 883         if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 884                 /*
 885                  * At this point we know that fork() succeeded, but exec()
 886                  * failed. Errors have been reported to our stderr.
 887                  */
 888                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
 889                 child_err_spew(cmd, &cerr);
 890                 failed_errno = errno;
 891                 cmd->pid = -1;
 892         }
 893         close(notify_pipe[0]);
 894
 895         if (null_fd >= 0)
 896                 close(null_fd);
 897         strvec_clear(&argv);
 898         free(childenv);
 899 }
 900 end_of_spawn:
 901
 902 #else
 903 {
 904         int fhin = 0, fhout = 1, fherr = 2;
 905         const char **sargv = cmd->argv;
 906         struct strvec nargv = STRVEC_INIT;
 907
 908         if (cmd->no_stdin)
 909                 fhin = open("/dev/null", O_RDWR);
 910         else if (need_in)
 911                 fhin = dup(fdin[0]);
 912         else if (cmd->in)
 913                 fhin = dup(cmd->in);
 914
 915         if (cmd->no_stderr)
 916                 fherr = open("/dev/null", O_RDWR);
 917         else if (need_err)
 918                 fherr = dup(fderr[1]);
 919         else if (cmd->err > 2)
 920                 fherr = dup(cmd->err);
 921
 922         if (cmd->no_stdout)
 923                 fhout = open("/dev/null", O_RDWR);
 924         else if (cmd->stdout_to_stderr)
 925                 fhout = dup(fherr);
 926         else if (need_out)
 927                 fhout = dup(fdout[1]);
 928         else if (cmd->out > 1)
 929                 fhout = dup(cmd->out);
 930
 931         if (cmd->git_cmd)
 932                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 933         else if (cmd->use_shell)
 934                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 935
 936         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 937                         cmd->dir, fhin, fhout, fherr);
 938         failed_errno = errno;
 939         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 940                 error_errno("cannot spawn %s", cmd->argv[0]);
 941         if (cmd->clean_on_exit && cmd->pid >= 0)
 942                 mark_child_for_cleanup(cmd->pid, cmd);
 943
 944         strvec_clear(&nargv);
 945         cmd->argv = sargv;
 946         if (fhin != 0)
 947                 close(fhin);
 948         if (fhout != 1)
 949                 close(fhout);
 950         if (fherr != 2)
 951                 close(fherr);
 952 }
 953 #endif
 954
 955         if (cmd->pid < 0) {
 956                 trace2_child_exit(cmd, -1);
 957
 958                 if (need_in)
 959                         close_pair(fdin);
 960                 else if (cmd->in)
 961                         close(cmd->in);
 962                 if (need_out)
 963                         close_pair(fdout);
 964                 else if (cmd->out)
 965                         close(cmd->out);
 966                 if (need_err)
 967                         close_pair(fderr);
 968                 else if (cmd->err)
 969                         close(cmd->err);
 970                 child_process_clear(cmd);
 971                 errno = failed_errno;
 972                 return -1;
 973         }
 974
 975         if (need_in)
 976                 close(fdin[0]);
 977         else if (cmd->in)
 978                 close(cmd->in);
 979
 980         if (need_out)
 981                 close(fdout[1]);
 982         else if (cmd->out)
 983                 close(cmd->out);
 984
 985         if (need_err)
 986                 close(fderr[1]);
 987         else if (cmd->err)
 988                 close(cmd->err);
 989
 990         return 0;
 991 }
 992
 993 int finish_command(struct child_process *cmd)
 994 {
 995         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 996         trace2_child_exit(cmd, ret);
 997         child_process_clear(cmd);
 998         invalidate_lstat_cache();
 999         return ret;
1000 }
1001
1002 int finish_command_in_signal(struct child_process *cmd)
1003 {
1004         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
1005         trace2_child_exit(cmd, ret);
1006         return ret;
1007 }
1008
1009
1010 int run_command(struct child_process *cmd)
1011 {
1012         int code;
1013
1014         if (cmd->out < 0 || cmd->err < 0)
1015                 BUG("run_command with a pipe can cause deadlock");
1016
1017         code = start_command(cmd);
1018         if (code)
1019                 return code;
1020         return finish_command(cmd);
1021 }
1022
1023 int run_command_v_opt(const char **argv, int opt)
1024 {
1025         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
1026 }
1027
1028 int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
1029 {
1030         return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
1031 }
1032
1033 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
1034 {
1035         return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
1036 }
1037
1038 int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
1039                                  const char *const *env, const char *tr2_class)
1040 {
1041         struct child_process cmd = CHILD_PROCESS_INIT;
1042         cmd.argv = argv;
1043         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
1044         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
1045         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
1046         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
1047         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
1048         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
1049         cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
1050         cmd.close_object_store = opt & RUN_CLOSE_OBJECT_STORE ? 1 : 0;
1051         cmd.dir = dir;
1052         cmd.env = env;
1053         cmd.trace2_child_class = tr2_class;
1054         return run_command(&cmd);
1055 }
1056
1057 #ifndef NO_PTHREADS
1058 static pthread_t main_thread;
1059 static int main_thread_set;
1060 static pthread_key_t async_key;
1061 static pthread_key_t async_die_counter;
1062
1063 static void *run_thread(void *data)
1064 {
1065         struct async *async = data;
1066         intptr_t ret;
1067
1068         if (async->isolate_sigpipe) {
1069                 sigset_t mask;
1070                 sigemptyset(&mask);
1071                 sigaddset(&mask, SIGPIPE);
1072                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
1073                         ret = error("unable to block SIGPIPE in async thread");
1074                         return (void *)ret;
1075                 }
1076         }
1077
1078         pthread_setspecific(async_key, async);
1079         ret = async->proc(async->proc_in, async->proc_out, async->data);
1080         return (void *)ret;
1081 }
1082
1083 static NORETURN void die_async(const char *err, va_list params)
1084 {
1085         vreportf("fatal: ", err, params);
1086
1087         if (in_async()) {
1088                 struct async *async = pthread_getspecific(async_key);
1089                 if (async->proc_in >= 0)
1090                         close(async->proc_in);
1091                 if (async->proc_out >= 0)
1092                         close(async->proc_out);
1093                 pthread_exit((void *)128);
1094         }
1095
1096         exit(128);
1097 }
1098
1099 static int async_die_is_recursing(void)
1100 {
1101         void *ret = pthread_getspecific(async_die_counter);
1102         pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
1103         return ret != NULL;
1104 }
1105
1106 int in_async(void)
1107 {
1108         if (!main_thread_set)
1109                 return 0; /* no asyncs started yet */
1110         return !pthread_equal(main_thread, pthread_self());
1111 }
1112
1113 static void NORETURN async_exit(int code)
1114 {
1115         pthread_exit((void *)(intptr_t)code);
1116 }
1117
1118 #else
1119
1120 static struct {
1121         void (**handlers)(void);
1122         size_t nr;
1123         size_t alloc;
1124 } git_atexit_hdlrs;
1125
1126 static int git_atexit_installed;
1127
1128 static void git_atexit_dispatch(void)
1129 {
1130         size_t i;
1131
1132         for (i=git_atexit_hdlrs.nr ; i ; i--)
1133                 git_atexit_hdlrs.handlers[i-1]();
1134 }
1135
1136 static void git_atexit_clear(void)
1137 {
1138         free(git_atexit_hdlrs.handlers);
1139         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1140         git_atexit_installed = 0;
1141 }
1142
1143 #undef atexit
1144 int git_atexit(void (*handler)(void))
1145 {
1146         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1147         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1148         if (!git_atexit_installed) {
1149                 if (atexit(&git_atexit_dispatch))
1150                         return -1;
1151                 git_atexit_installed = 1;
1152         }
1153         return 0;
1154 }
1155 #define atexit git_atexit
1156
1157 static int process_is_async;
1158 int in_async(void)
1159 {
1160         return process_is_async;
1161 }
1162
1163 static void NORETURN async_exit(int code)
1164 {
1165         exit(code);
1166 }
1167
1168 #endif
1169
1170 void check_pipe(int err)
1171 {
1172         if (err == EPIPE) {
1173                 if (in_async())
1174                         async_exit(141);
1175
1176                 signal(SIGPIPE, SIG_DFL);
1177                 raise(SIGPIPE);
1178                 /* Should never happen, but just in case... */
1179                 exit(141);
1180         }
1181 }
1182
1183 int start_async(struct async *async)
1184 {
1185         int need_in, need_out;
1186         int fdin[2], fdout[2];
1187         int proc_in, proc_out;
1188
1189         need_in = async->in < 0;
1190         if (need_in) {
1191                 if (pipe(fdin) < 0) {
1192                         if (async->out > 0)
1193                                 close(async->out);
1194                         return error_errno("cannot create pipe");
1195                 }
1196                 async->in = fdin[1];
1197         }
1198
1199         need_out = async->out < 0;
1200         if (need_out) {
1201                 if (pipe(fdout) < 0) {
1202                         if (need_in)
1203                                 close_pair(fdin);
1204                         else if (async->in)
1205                                 close(async->in);
1206                         return error_errno("cannot create pipe");
1207                 }
1208                 async->out = fdout[0];
1209         }
1210
1211         if (need_in)
1212                 proc_in = fdin[0];
1213         else if (async->in)
1214                 proc_in = async->in;
1215         else
1216                 proc_in = -1;
1217
1218         if (need_out)
1219                 proc_out = fdout[1];
1220         else if (async->out)
1221                 proc_out = async->out;
1222         else
1223                 proc_out = -1;
1224
1225 #ifdef NO_PTHREADS
1226         /* Flush stdio before fork() to avoid cloning buffers */
1227         fflush(NULL);
1228
1229         async->pid = fork();
1230         if (async->pid < 0) {
1231                 error_errno("fork (async) failed");
1232                 goto error;
1233         }
1234         if (!async->pid) {
1235                 if (need_in)
1236                         close(fdin[1]);
1237                 if (need_out)
1238                         close(fdout[0]);
1239                 git_atexit_clear();
1240                 process_is_async = 1;
1241                 exit(!!async->proc(proc_in, proc_out, async->data));
1242         }
1243
1244         mark_child_for_cleanup(async->pid, NULL);
1245
1246         if (need_in)
1247                 close(fdin[0]);
1248         else if (async->in)
1249                 close(async->in);
1250
1251         if (need_out)
1252                 close(fdout[1]);
1253         else if (async->out)
1254                 close(async->out);
1255 #else
1256         if (!main_thread_set) {
1257                 /*
1258                  * We assume that the first time that start_async is called
1259                  * it is from the main thread.
1260                  */
1261                 main_thread_set = 1;
1262                 main_thread = pthread_self();
1263                 pthread_key_create(&async_key, NULL);
1264                 pthread_key_create(&async_die_counter, NULL);
1265                 set_die_routine(die_async);
1266                 set_die_is_recursing_routine(async_die_is_recursing);
1267         }
1268
1269         if (proc_in >= 0)
1270                 set_cloexec(proc_in);
1271         if (proc_out >= 0)
1272                 set_cloexec(proc_out);
1273         async->proc_in = proc_in;
1274         async->proc_out = proc_out;
1275         {
1276                 int err = pthread_create(&async->tid, NULL, run_thread, async);
1277                 if (err) {
1278                         error(_("cannot create async thread: %s"), strerror(err));
1279                         goto error;
1280                 }
1281         }
1282 #endif
1283         return 0;
1284
1285 error:
1286         if (need_in)
1287                 close_pair(fdin);
1288         else if (async->in)
1289                 close(async->in);
1290
1291         if (need_out)
1292                 close_pair(fdout);
1293         else if (async->out)
1294                 close(async->out);
1295         return -1;
1296 }
1297
1298 int finish_async(struct async *async)
1299 {
1300 #ifdef NO_PTHREADS
1301         int ret = wait_or_whine(async->pid, "child process", 0);
1302
1303         invalidate_lstat_cache();
1304
1305         return ret;
1306 #else
1307         void *ret = (void *)(intptr_t)(-1);
1308
1309         if (pthread_join(async->tid, &ret))
1310                 error("pthread_join failed");
1311         invalidate_lstat_cache();
1312         return (int)(intptr_t)ret;
1313
1314 #endif
1315 }
1316
1317 int async_with_fork(void)
1318 {
1319 #ifdef NO_PTHREADS
1320         return 1;
1321 #else
1322         return 0;
1323 #endif
1324 }
1325
1326 int run_hook_ve(const char *const *env, const char *name, va_list args)
1327 {
1328         struct child_process hook = CHILD_PROCESS_INIT;
1329         const char *p;
1330
1331         p = find_hook(name);
1332         if (!p)
1333                 return 0;
1334
1335         strvec_push(&hook.args, p);
1336         while ((p = va_arg(args, const char *)))
1337                 strvec_push(&hook.args, p);
1338         hook.env = env;
1339         hook.no_stdin = 1;
1340         hook.stdout_to_stderr = 1;
1341         hook.trace2_hook_name = name;
1342
1343         return run_command(&hook);
1344 }
1345
1346 int run_hook_le(const char *const *env, const char *name, ...)
1347 {
1348         va_list args;
1349         int ret;
1350
1351         va_start(args, name);
1352         ret = run_hook_ve(env, name, args);
1353         va_end(args);
1354
1355         return ret;
1356 }
1357
1358 struct io_pump {
1359         /* initialized by caller */
1360         int fd;
1361         int type; /* POLLOUT or POLLIN */
1362         union {
1363                 struct {
1364                         const char *buf;
1365                         size_t len;
1366                 } out;
1367                 struct {
1368                         struct strbuf *buf;
1369                         size_t hint;
1370                 } in;
1371         } u;
1372
1373         /* returned by pump_io */
1374         int error; /* 0 for success, otherwise errno */
1375
1376         /* internal use */
1377         struct pollfd *pfd;
1378 };
1379
1380 static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1381 {
1382         int pollsize = 0;
1383         int i;
1384
1385         for (i = 0; i < nr; i++) {
1386                 struct io_pump *io = &slots[i];
1387                 if (io->fd < 0)
1388                         continue;
1389                 pfd[pollsize].fd = io->fd;
1390                 pfd[pollsize].events = io->type;
1391                 io->pfd = &pfd[pollsize++];
1392         }
1393
1394         if (!pollsize)
1395                 return 0;
1396
1397         if (poll(pfd, pollsize, -1) < 0) {
1398                 if (errno == EINTR)
1399                         return 1;
1400                 die_errno("poll failed");
1401         }
1402
1403         for (i = 0; i < nr; i++) {
1404                 struct io_pump *io = &slots[i];
1405
1406                 if (io->fd < 0)
1407                         continue;
1408
1409                 if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1410                         continue;
1411
1412                 if (io->type == POLLOUT) {
1413                         ssize_t len = xwrite(io->fd,
1414                                              io->u.out.buf, io->u.out.len);
1415                         if (len < 0) {
1416                                 io->error = errno;
1417                                 close(io->fd);
1418                                 io->fd = -1;
1419                         } else {
1420                                 io->u.out.buf += len;
1421                                 io->u.out.len -= len;
1422                                 if (!io->u.out.len) {
1423                                         close(io->fd);
1424                                         io->fd = -1;
1425                                 }
1426                         }
1427                 }
1428
1429                 if (io->type == POLLIN) {
1430                         ssize_t len = strbuf_read_once(io->u.in.buf,
1431                                                        io->fd, io->u.in.hint);
1432                         if (len < 0)
1433                                 io->error = errno;
1434                         if (len <= 0) {
1435                                 close(io->fd);
1436                                 io->fd = -1;
1437                         }
1438                 }
1439         }
1440
1441         return 1;
1442 }
1443
1444 static int pump_io(struct io_pump *slots, int nr)
1445 {
1446         struct pollfd *pfd;
1447         int i;
1448
1449         for (i = 0; i < nr; i++)
1450                 slots[i].error = 0;
1451
1452         ALLOC_ARRAY(pfd, nr);
1453         while (pump_io_round(slots, nr, pfd))
1454                 ; /* nothing */
1455         free(pfd);
1456
1457         /* There may be multiple errno values, so just pick the first. */
1458         for (i = 0; i < nr; i++) {
1459                 if (slots[i].error) {
1460                         errno = slots[i].error;
1461                         return -1;
1462                 }
1463         }
1464         return 0;
1465 }
1466
1467
1468 int pipe_command(struct child_process *cmd,
1469                  const char *in, size_t in_len,
1470                  struct strbuf *out, size_t out_hint,
1471                  struct strbuf *err, size_t err_hint)
1472 {
1473         struct io_pump io[3];
1474         int nr = 0;
1475
1476         if (in)
1477                 cmd->in = -1;
1478         if (out)
1479                 cmd->out = -1;
1480         if (err)
1481                 cmd->err = -1;
1482
1483         if (start_command(cmd) < 0)
1484                 return -1;
1485
1486         if (in) {
1487                 io[nr].fd = cmd->in;
1488                 io[nr].type = POLLOUT;
1489                 io[nr].u.out.buf = in;
1490                 io[nr].u.out.len = in_len;
1491                 nr++;
1492         }
1493         if (out) {
1494                 io[nr].fd = cmd->out;
1495                 io[nr].type = POLLIN;
1496                 io[nr].u.in.buf = out;
1497                 io[nr].u.in.hint = out_hint;
1498                 nr++;
1499         }
1500         if (err) {
1501                 io[nr].fd = cmd->err;
1502                 io[nr].type = POLLIN;
1503                 io[nr].u.in.buf = err;
1504                 io[nr].u.in.hint = err_hint;
1505                 nr++;
1506         }
1507
1508         if (pump_io(io, nr) < 0) {
1509                 finish_command(cmd); /* throw away exit code */
1510                 return -1;
1511         }
1512
1513         return finish_command(cmd);
1514 }
1515
1516 enum child_state {
1517         GIT_CP_FREE,
1518         GIT_CP_WORKING,
1519         GIT_CP_WAIT_CLEANUP,
1520 };
1521
1522 struct parallel_processes {
1523         void *data;
1524
1525         int max_processes;
1526         int nr_processes;
1527
1528         get_next_task_fn get_next_task;
1529         start_failure_fn start_failure;
1530         task_finished_fn task_finished;
1531
1532         struct {
1533                 enum child_state state;
1534                 struct child_process process;
1535                 struct strbuf err;
1536                 void *data;
1537         } *children;
1538         /*
1539          * The struct pollfd is logically part of *children,
1540          * but the system call expects it as its own array.
1541          */
1542         struct pollfd *pfd;
1543
1544         unsigned shutdown : 1;
1545
1546         int output_owner;
1547         struct strbuf buffered_output; /* of finished children */
1548 };
1549
1550 static int default_start_failure(struct strbuf *out,
1551                                  void *pp_cb,
1552                                  void *pp_task_cb)
1553 {
1554         return 0;
1555 }
1556
1557 static int default_task_finished(int result,
1558                                  struct strbuf *out,
1559                                  void *pp_cb,
1560                                  void *pp_task_cb)
1561 {
1562         return 0;
1563 }
1564
1565 static void kill_children(struct parallel_processes *pp, int signo)
1566 {
1567         int i, n = pp->max_processes;
1568
1569         for (i = 0; i < n; i++)
1570                 if (pp->children[i].state == GIT_CP_WORKING)
1571                         kill(pp->children[i].process.pid, signo);
1572 }
1573
1574 static struct parallel_processes *pp_for_signal;
1575
1576 static void handle_children_on_signal(int signo)
1577 {
1578         kill_children(pp_for_signal, signo);
1579         sigchain_pop(signo);
1580         raise(signo);
1581 }
1582
1583 static void pp_init(struct parallel_processes *pp,
1584                     int n,
1585                     get_next_task_fn get_next_task,
1586                     start_failure_fn start_failure,
1587                     task_finished_fn task_finished,
1588                     void *data)
1589 {
1590         int i;
1591
1592         if (n < 1)
1593                 n = online_cpus();
1594
1595         pp->max_processes = n;
1596
1597         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1598
1599         pp->data = data;
1600         if (!get_next_task)
1601                 BUG("you need to specify a get_next_task function");
1602         pp->get_next_task = get_next_task;
1603
1604         pp->start_failure = start_failure ? start_failure : default_start_failure;
1605         pp->task_finished = task_finished ? task_finished : default_task_finished;
1606
1607         pp->nr_processes = 0;
1608         pp->output_owner = 0;
1609         pp->shutdown = 0;
1610         CALLOC_ARRAY(pp->children, n);
1611         CALLOC_ARRAY(pp->pfd, n);
1612         strbuf_init(&pp->buffered_output, 0);
1613
1614         for (i = 0; i < n; i++) {
1615                 strbuf_init(&pp->children[i].err, 0);
1616                 child_process_init(&pp->children[i].process);
1617                 pp->pfd[i].events = POLLIN | POLLHUP;
1618                 pp->pfd[i].fd = -1;
1619         }
1620
1621         pp_for_signal = pp;
1622         sigchain_push_common(handle_children_on_signal);
1623 }
1624
1625 static void pp_cleanup(struct parallel_processes *pp)
1626 {
1627         int i;
1628
1629         trace_printf("run_processes_parallel: done");
1630         for (i = 0; i < pp->max_processes; i++) {
1631                 strbuf_release(&pp->children[i].err);
1632                 child_process_clear(&pp->children[i].process);
1633         }
1634
1635         free(pp->children);
1636         free(pp->pfd);
1637
1638         /*
1639          * When get_next_task added messages to the buffer in its last
1640          * iteration, the buffered output is non empty.
1641          */
1642         strbuf_write(&pp->buffered_output, stderr);
1643         strbuf_release(&pp->buffered_output);
1644
1645         sigchain_pop_common();
1646 }
1647
1648 /* returns
1649  *  0 if a new task was started.
1650  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1651  *    problem with starting a new command)
1652  * <0 no new job was started, user wishes to shutdown early. Use negative code
1653  *    to signal the children.
1654  */
1655 static int pp_start_one(struct parallel_processes *pp)
1656 {
1657         int i, code;
1658
1659         for (i = 0; i < pp->max_processes; i++)
1660                 if (pp->children[i].state == GIT_CP_FREE)
1661                         break;
1662         if (i == pp->max_processes)
1663                 BUG("bookkeeping is hard");
1664
1665         code = pp->get_next_task(&pp->children[i].process,
1666                                  &pp->children[i].err,
1667                                  pp->data,
1668                                  &pp->children[i].data);
1669         if (!code) {
1670                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1671                 strbuf_reset(&pp->children[i].err);
1672                 return 1;
1673         }
1674         pp->children[i].process.err = -1;
1675         pp->children[i].process.stdout_to_stderr = 1;
1676         pp->children[i].process.no_stdin = 1;
1677
1678         if (start_command(&pp->children[i].process)) {
1679                 code = pp->start_failure(&pp->children[i].err,
1680                                          pp->data,
1681                                          pp->children[i].data);
1682                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1683                 strbuf_reset(&pp->children[i].err);
1684                 if (code)
1685                         pp->shutdown = 1;
1686                 return code;
1687         }
1688
1689         pp->nr_processes++;
1690         pp->children[i].state = GIT_CP_WORKING;
1691         pp->pfd[i].fd = pp->children[i].process.err;
1692         return 0;
1693 }
1694
1695 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1696 {
1697         int i;
1698
1699         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1700                 if (errno == EINTR)
1701                         continue;
1702                 pp_cleanup(pp);
1703                 die_errno("poll");
1704         }
1705
1706         /* Buffer output from all pipes. */
1707         for (i = 0; i < pp->max_processes; i++) {
1708                 if (pp->children[i].state == GIT_CP_WORKING &&
1709                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1710                         int n = strbuf_read_once(&pp->children[i].err,
1711                                                  pp->children[i].process.err, 0);
1712                         if (n == 0) {
1713                                 close(pp->children[i].process.err);
1714                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1715                         } else if (n < 0)
1716                                 if (errno != EAGAIN)
1717                                         die_errno("read");
1718                 }
1719         }
1720 }
1721
1722 static void pp_output(struct parallel_processes *pp)
1723 {
1724         int i = pp->output_owner;
1725         if (pp->children[i].state == GIT_CP_WORKING &&
1726             pp->children[i].err.len) {
1727                 strbuf_write(&pp->children[i].err, stderr);
1728                 strbuf_reset(&pp->children[i].err);
1729         }
1730 }
1731
1732 static int pp_collect_finished(struct parallel_processes *pp)
1733 {
1734         int i, code;
1735         int n = pp->max_processes;
1736         int result = 0;
1737
1738         while (pp->nr_processes > 0) {
1739                 for (i = 0; i < pp->max_processes; i++)
1740                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1741                                 break;
1742                 if (i == pp->max_processes)
1743                         break;
1744
1745                 code = finish_command(&pp->children[i].process);
1746
1747                 code = pp->task_finished(code,
1748                                          &pp->children[i].err, pp->data,
1749                                          pp->children[i].data);
1750
1751                 if (code)
1752                         result = code;
1753                 if (code < 0)
1754                         break;
1755
1756                 pp->nr_processes--;
1757                 pp->children[i].state = GIT_CP_FREE;
1758                 pp->pfd[i].fd = -1;
1759                 child_process_init(&pp->children[i].process);
1760
1761                 if (i != pp->output_owner) {
1762                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1763                         strbuf_reset(&pp->children[i].err);
1764                 } else {
1765                         strbuf_write(&pp->children[i].err, stderr);
1766                         strbuf_reset(&pp->children[i].err);
1767
1768                         /* Output all other finished child processes */
1769                         strbuf_write(&pp->buffered_output, stderr);
1770                         strbuf_reset(&pp->buffered_output);
1771
1772                         /*
1773                          * Pick next process to output live.
1774                          * NEEDSWORK:
1775                          * For now we pick it randomly by doing a round
1776                          * robin. Later we may want to pick the one with
1777                          * the most output or the longest or shortest
1778                          * running process time.
1779                          */
1780                         for (i = 0; i < n; i++)
1781                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1782                                         break;
1783                         pp->output_owner = (pp->output_owner + i) % n;
1784                 }
1785         }
1786         return result;
1787 }
1788
1789 int run_processes_parallel(int n,
1790                            get_next_task_fn get_next_task,
1791                            start_failure_fn start_failure,
1792                            task_finished_fn task_finished,
1793                            void *pp_cb)
1794 {
1795         int i, code;
1796         int output_timeout = 100;
1797         int spawn_cap = 4;
1798         struct parallel_processes pp;
1799
1800         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1801         while (1) {
1802                 for (i = 0;
1803                     i < spawn_cap && !pp.shutdown &&
1804                     pp.nr_processes < pp.max_processes;
1805                     i++) {
1806                         code = pp_start_one(&pp);
1807                         if (!code)
1808                                 continue;
1809                         if (code < 0) {
1810                                 pp.shutdown = 1;
1811                                 kill_children(&pp, -code);
1812                         }
1813                         break;
1814                 }
1815                 if (!pp.nr_processes)
1816                         break;
1817                 pp_buffer_stderr(&pp, output_timeout);
1818                 pp_output(&pp);
1819                 code = pp_collect_finished(&pp);
1820                 if (code) {
1821                         pp.shutdown = 1;
1822                         if (code < 0)
1823                                 kill_children(&pp, -code);
1824                 }
1825         }
1826
1827         pp_cleanup(&pp);
1828         return 0;
1829 }
1830
1831 int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
1832                                start_failure_fn start_failure,
1833                                task_finished_fn task_finished, void *pp_cb,
1834                                const char *tr2_category, const char *tr2_label)
1835 {
1836         int result;
1837
1838         trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
1839                                    ((n < 1) ? online_cpus() : n));
1840
1841         result = run_processes_parallel(n, get_next_task, start_failure,
1842                                         task_finished, pp_cb);
1843
1844         trace2_region_leave(tr2_category, tr2_label, NULL);
1845
1846         return result;
1847 }
1848
1849 int run_auto_maintenance(int quiet)
1850 {
1851         int enabled;
1852         struct child_process maint = CHILD_PROCESS_INIT;
1853
1854         if (!git_config_get_bool("maintenance.auto", &enabled) &&
1855             !enabled)
1856                 return 0;
1857
1858         maint.git_cmd = 1;
1859         maint.close_object_store = 1;
1860         strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
1861         strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
1862
1863         return run_command(&maint);
1864 }
1865
1866 void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir)
1867 {
1868         const char * const *var;
1869
1870         for (var = local_repo_env; *var; var++) {
1871                 if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
1872                     strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
1873                         strvec_push(env_array, *var);
1874         }
1875         strvec_pushf(env_array, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
1876 }
1877
1878 enum start_bg_result start_bg_command(struct child_process *cmd,
1879                                       start_bg_wait_cb *wait_cb,
1880                                       void *cb_data,
1881                                       unsigned int timeout_sec)
1882 {
1883         enum start_bg_result sbgr = SBGR_ERROR;
1884         int ret;
1885         int wait_status;
1886         pid_t pid_seen;
1887         time_t time_limit;
1888
1889         /*
1890          * We do not allow clean-on-exit because the child process
1891          * should persist in the background and possibly/probably
1892          * after this process exits.  So we don't want to kill the
1893          * child during our atexit routine.
1894          */
1895         if (cmd->clean_on_exit)
1896                 BUG("start_bg_command() does not allow non-zero clean_on_exit");
1897
1898         if (!cmd->trace2_child_class)
1899                 cmd->trace2_child_class = "background";
1900
1901         ret = start_command(cmd);
1902         if (ret) {
1903                 /*
1904                  * We assume that if `start_command()` fails, we
1905                  * either get a complete `trace2_child_start() /
1906                  * trace2_child_exit()` pair or it fails before the
1907                  * `trace2_child_start()` is emitted, so we do not
1908                  * need to worry about it here.
1909                  *
1910                  * We also assume that `start_command()` does not add
1911                  * us to the cleanup list.  And that it calls
1912                  * calls `child_process_clear()`.
1913                  */
1914                 sbgr = SBGR_ERROR;
1915                 goto done;
1916         }
1917
1918         time(&time_limit);
1919         time_limit += timeout_sec;
1920
1921 wait:
1922         pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
1923
1924         if (!pid_seen) {
1925                 /*
1926                  * The child is currently running.  Ask the callback
1927                  * if the child is ready to do work or whether we
1928                  * should keep waiting for it to boot up.
1929                  */
1930                 ret = (*wait_cb)(cmd, cb_data);
1931                 if (!ret) {
1932                         /*
1933                          * The child is running and "ready".
1934                          */
1935                         trace2_child_ready(cmd, "ready");
1936                         sbgr = SBGR_READY;
1937                         goto done;
1938                 } else if (ret > 0) {
1939                         /*
1940                          * The callback said to give it more time to boot up
1941                          * (subject to our timeout limit).
1942                          */
1943                         time_t now;
1944
1945                         time(&now);
1946                         if (now < time_limit)
1947                                 goto wait;
1948
1949                         /*
1950                          * Our timeout has expired.  We don't try to
1951                          * kill the child, but rather let it continue
1952                          * (hopefully) trying to startup.
1953                          */
1954                         trace2_child_ready(cmd, "timeout");
1955                         sbgr = SBGR_TIMEOUT;
1956                         goto done;
1957                 } else {
1958                         /*
1959                          * The cb gave up on this child.  It is still running,
1960                          * but our cb got an error trying to probe it.
1961                          */
1962                         trace2_child_ready(cmd, "error");
1963                         sbgr = SBGR_CB_ERROR;
1964                         goto done;
1965                 }
1966         }
1967
1968         else if (pid_seen == cmd->pid) {
1969                 int child_code = -1;
1970
1971                 /*
1972                  * The child started, but exited or was terminated
1973                  * before becoming "ready".
1974                  *
1975                  * We try to match the behavior of `wait_or_whine()`
1976                  * WRT the handling of WIFSIGNALED() and WIFEXITED()
1977                  * and convert the child's status to a return code for
1978                  * tracing purposes and emit the `trace2_child_exit()`
1979                  * event.
1980                  *
1981                  * We do not want the wait_or_whine() error message
1982                  * because we will be called by client-side library
1983                  * routines.
1984                  */
1985                 if (WIFEXITED(wait_status))
1986                         child_code = WEXITSTATUS(wait_status);
1987                 else if (WIFSIGNALED(wait_status))
1988                         child_code = WTERMSIG(wait_status) + 128;
1989                 trace2_child_exit(cmd, child_code);
1990
1991                 sbgr = SBGR_DIED;
1992                 goto done;
1993         }
1994
1995         else if (pid_seen < 0 && errno == EINTR)
1996                 goto wait;
1997
1998         trace2_child_exit(cmd, -1);
1999         sbgr = SBGR_ERROR;
2000
2001 done:
2002         child_process_clear(cmd);
2003         invalidate_lstat_cache();
2004         return sbgr;
2005 }