run-command.con commit t5702: use test_commit_bulk (9516345)
   1#include "cache.h"
   2#include "run-command.h"
   3#include "exec-cmd.h"
   4#include "sigchain.h"
   5#include "argv-array.h"
   6#include "thread-utils.h"
   7#include "strbuf.h"
   8#include "string-list.h"
   9#include "quote.h"
  10
  11void child_process_init(struct child_process *child)
  12{
  13        memset(child, 0, sizeof(*child));
  14        argv_array_init(&child->args);
  15        argv_array_init(&child->env_array);
  16}
  17
  18void child_process_clear(struct child_process *child)
  19{
  20        argv_array_clear(&child->args);
  21        argv_array_clear(&child->env_array);
  22}
  23
  24struct child_to_clean {
  25        pid_t pid;
  26        struct child_process *process;
  27        struct child_to_clean *next;
  28};
  29static struct child_to_clean *children_to_clean;
  30static int installed_child_cleanup_handler;
  31
  32static void cleanup_children(int sig, int in_signal)
  33{
  34        struct child_to_clean *children_to_wait_for = NULL;
  35
  36        while (children_to_clean) {
  37                struct child_to_clean *p = children_to_clean;
  38                children_to_clean = p->next;
  39
  40                if (p->process && !in_signal) {
  41                        struct child_process *process = p->process;
  42                        if (process->clean_on_exit_handler) {
  43                                trace_printf(
  44                                        "trace: run_command: running exit handler for pid %"
  45                                        PRIuMAX, (uintmax_t)p->pid
  46                                );
  47                                process->clean_on_exit_handler(process);
  48                        }
  49                }
  50
  51                kill(p->pid, sig);
  52
  53                if (p->process && p->process->wait_after_clean) {
  54                        p->next = children_to_wait_for;
  55                        children_to_wait_for = p;
  56                } else {
  57                        if (!in_signal)
  58                                free(p);
  59                }
  60        }
  61
  62        while (children_to_wait_for) {
  63                struct child_to_clean *p = children_to_wait_for;
  64                children_to_wait_for = p->next;
  65
  66                while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
  67                        ; /* spin waiting for process exit or error */
  68
  69                if (!in_signal)
  70                        free(p);
  71        }
  72}
  73
  74static void cleanup_children_on_signal(int sig)
  75{
  76        cleanup_children(sig, 1);
  77        sigchain_pop(sig);
  78        raise(sig);
  79}
  80
  81static void cleanup_children_on_exit(void)
  82{
  83        cleanup_children(SIGTERM, 0);
  84}
  85
  86static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
  87{
  88        struct child_to_clean *p = xmalloc(sizeof(*p));
  89        p->pid = pid;
  90        p->process = process;
  91        p->next = children_to_clean;
  92        children_to_clean = p;
  93
  94        if (!installed_child_cleanup_handler) {
  95                atexit(cleanup_children_on_exit);
  96                sigchain_push_common(cleanup_children_on_signal);
  97                installed_child_cleanup_handler = 1;
  98        }
  99}
 100
 101static void clear_child_for_cleanup(pid_t pid)
 102{
 103        struct child_to_clean **pp;
 104
 105        for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
 106                struct child_to_clean *clean_me = *pp;
 107
 108                if (clean_me->pid == pid) {
 109                        *pp = clean_me->next;
 110                        free(clean_me);
 111                        return;
 112                }
 113        }
 114}
 115
 116static inline void close_pair(int fd[2])
 117{
 118        close(fd[0]);
 119        close(fd[1]);
 120}
 121
 122int is_executable(const char *name)
 123{
 124        struct stat st;
 125
 126        if (stat(name, &st) || /* stat, not lstat */
 127            !S_ISREG(st.st_mode))
 128                return 0;
 129
 130#if defined(GIT_WINDOWS_NATIVE)
 131        /*
 132         * On Windows there is no executable bit. The file extension
 133         * indicates whether it can be run as an executable, and Git
 134         * has special-handling to detect scripts and launch them
 135         * through the indicated script interpreter. We test for the
 136         * file extension first because virus scanners may make
 137         * it quite expensive to open many files.
 138         */
 139        if (ends_with(name, ".exe"))
 140                return S_IXUSR;
 141
 142{
 143        /*
 144         * Now that we know it does not have an executable extension,
 145         * peek into the file instead.
 146         */
 147        char buf[3] = { 0 };
 148        int n;
 149        int fd = open(name, O_RDONLY);
 150        st.st_mode &= ~S_IXUSR;
 151        if (fd >= 0) {
 152                n = read(fd, buf, 2);
 153                if (n == 2)
 154                        /* look for a she-bang */
 155                        if (!strcmp(buf, "#!"))
 156                                st.st_mode |= S_IXUSR;
 157                close(fd);
 158        }
 159}
 160#endif
 161        return st.st_mode & S_IXUSR;
 162}
 163
 164/*
 165 * Search $PATH for a command.  This emulates the path search that
 166 * execvp would perform, without actually executing the command so it
 167 * can be used before fork() to prepare to run a command using
 168 * execve() or after execvp() to diagnose why it failed.
 169 *
 170 * The caller should ensure that file contains no directory
 171 * separators.
 172 *
 173 * Returns the path to the command, as found in $PATH or NULL if the
 174 * command could not be found.  The caller inherits ownership of the memory
 175 * used to store the resultant path.
 176 *
 177 * This should not be used on Windows, where the $PATH search rules
 178 * are more complicated (e.g., a search for "foo" should find
 179 * "foo.exe").
 180 */
 181static char *locate_in_PATH(const char *file)
 182{
 183        const char *p = getenv("PATH");
 184        struct strbuf buf = STRBUF_INIT;
 185
 186        if (!p || !*p)
 187                return NULL;
 188
 189        while (1) {
 190                const char *end = strchrnul(p, ':');
 191
 192                strbuf_reset(&buf);
 193
 194                /* POSIX specifies an empty entry as the current directory. */
 195                if (end != p) {
 196                        strbuf_add(&buf, p, end - p);
 197                        strbuf_addch(&buf, '/');
 198                }
 199                strbuf_addstr(&buf, file);
 200
 201                if (is_executable(buf.buf))
 202                        return strbuf_detach(&buf, NULL);
 203
 204                if (!*end)
 205                        break;
 206                p = end + 1;
 207        }
 208
 209        strbuf_release(&buf);
 210        return NULL;
 211}
 212
 213static int exists_in_PATH(const char *file)
 214{
 215        char *r = locate_in_PATH(file);
 216        free(r);
 217        return r != NULL;
 218}
 219
 220int sane_execvp(const char *file, char * const argv[])
 221{
 222#ifndef GIT_WINDOWS_NATIVE
 223        /*
 224         * execvp() doesn't return, so we all we can do is tell trace2
 225         * what we are about to do and let it leave a hint in the log
 226         * (unless of course the execvp() fails).
 227         *
 228         * we skip this for Windows because the compat layer already
 229         * has to emulate the execvp() call anyway.
 230         */
 231        int exec_id = trace2_exec(file, (const char **)argv);
 232#endif
 233
 234        if (!execvp(file, argv))
 235                return 0; /* cannot happen ;-) */
 236
 237#ifndef GIT_WINDOWS_NATIVE
 238        {
 239                int ec = errno;
 240                trace2_exec_result(exec_id, ec);
 241                errno = ec;
 242        }
 243#endif
 244
 245        /*
 246         * When a command can't be found because one of the directories
 247         * listed in $PATH is unsearchable, execvp reports EACCES, but
 248         * careful usability testing (read: analysis of occasional bug
 249         * reports) reveals that "No such file or directory" is more
 250         * intuitive.
 251         *
 252         * We avoid commands with "/", because execvp will not do $PATH
 253         * lookups in that case.
 254         *
 255         * The reassignment of EACCES to errno looks like a no-op below,
 256         * but we need to protect against exists_in_PATH overwriting errno.
 257         */
 258        if (errno == EACCES && !strchr(file, '/'))
 259                errno = exists_in_PATH(file) ? EACCES : ENOENT;
 260        else if (errno == ENOTDIR && !strchr(file, '/'))
 261                errno = ENOENT;
 262        return -1;
 263}
 264
 265static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 266{
 267        if (!argv[0])
 268                BUG("shell command is empty");
 269
 270        if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 271#ifndef GIT_WINDOWS_NATIVE
 272                argv_array_push(out, SHELL_PATH);
 273#else
 274                argv_array_push(out, "sh");
 275#endif
 276                argv_array_push(out, "-c");
 277
 278                /*
 279                 * If we have no extra arguments, we do not even need to
 280                 * bother with the "$@" magic.
 281                 */
 282                if (!argv[1])
 283                        argv_array_push(out, argv[0]);
 284                else
 285                        argv_array_pushf(out, "%s \"$@\"", argv[0]);
 286        }
 287
 288        argv_array_pushv(out, argv);
 289        return out->argv;
 290}
 291
 292#ifndef GIT_WINDOWS_NATIVE
 293static int child_notifier = -1;
 294
 295enum child_errcode {
 296        CHILD_ERR_CHDIR,
 297        CHILD_ERR_DUP2,
 298        CHILD_ERR_CLOSE,
 299        CHILD_ERR_SIGPROCMASK,
 300        CHILD_ERR_ENOENT,
 301        CHILD_ERR_SILENT,
 302        CHILD_ERR_ERRNO
 303};
 304
 305struct child_err {
 306        enum child_errcode err;
 307        int syserr; /* errno */
 308};
 309
 310static void child_die(enum child_errcode err)
 311{
 312        struct child_err buf;
 313
 314        buf.err = err;
 315        buf.syserr = errno;
 316
 317        /* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
 318        xwrite(child_notifier, &buf, sizeof(buf));
 319        _exit(1);
 320}
 321
 322static void child_dup2(int fd, int to)
 323{
 324        if (dup2(fd, to) < 0)
 325                child_die(CHILD_ERR_DUP2);
 326}
 327
 328static void child_close(int fd)
 329{
 330        if (close(fd))
 331                child_die(CHILD_ERR_CLOSE);
 332}
 333
 334static void child_close_pair(int fd[2])
 335{
 336        child_close(fd[0]);
 337        child_close(fd[1]);
 338}
 339
 340/*
 341 * parent will make it look like the child spewed a fatal error and died
 342 * this is needed to prevent changes to t0061.
 343 */
 344static void fake_fatal(const char *err, va_list params)
 345{
 346        vreportf("fatal: ", err, params);
 347}
 348
 349static void child_error_fn(const char *err, va_list params)
 350{
 351        const char msg[] = "error() should not be called in child\n";
 352        xwrite(2, msg, sizeof(msg) - 1);
 353}
 354
 355static void child_warn_fn(const char *err, va_list params)
 356{
 357        const char msg[] = "warn() should not be called in child\n";
 358        xwrite(2, msg, sizeof(msg) - 1);
 359}
 360
 361static void NORETURN child_die_fn(const char *err, va_list params)
 362{
 363        const char msg[] = "die() should not be called in child\n";
 364        xwrite(2, msg, sizeof(msg) - 1);
 365        _exit(2);
 366}
 367
 368/* this runs in the parent process */
 369static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 370{
 371        static void (*old_errfn)(const char *err, va_list params);
 372
 373        old_errfn = get_error_routine();
 374        set_error_routine(fake_fatal);
 375        errno = cerr->syserr;
 376
 377        switch (cerr->err) {
 378        case CHILD_ERR_CHDIR:
 379                error_errno("exec '%s': cd to '%s' failed",
 380                            cmd->argv[0], cmd->dir);
 381                break;
 382        case CHILD_ERR_DUP2:
 383                error_errno("dup2() in child failed");
 384                break;
 385        case CHILD_ERR_CLOSE:
 386                error_errno("close() in child failed");
 387                break;
 388        case CHILD_ERR_SIGPROCMASK:
 389                error_errno("sigprocmask failed restoring signals");
 390                break;
 391        case CHILD_ERR_ENOENT:
 392                error_errno("cannot run %s", cmd->argv[0]);
 393                break;
 394        case CHILD_ERR_SILENT:
 395                break;
 396        case CHILD_ERR_ERRNO:
 397                error_errno("cannot exec '%s'", cmd->argv[0]);
 398                break;
 399        }
 400        set_error_routine(old_errfn);
 401}
 402
 403static int prepare_cmd(struct argv_array *out, const struct child_process *cmd)
 404{
 405        if (!cmd->argv[0])
 406                BUG("command is empty");
 407
 408        /*
 409         * Add SHELL_PATH so in the event exec fails with ENOEXEC we can
 410         * attempt to interpret the command with 'sh'.
 411         */
 412        argv_array_push(out, SHELL_PATH);
 413
 414        if (cmd->git_cmd) {
 415                argv_array_push(out, "git");
 416                argv_array_pushv(out, cmd->argv);
 417        } else if (cmd->use_shell) {
 418                prepare_shell_cmd(out, cmd->argv);
 419        } else {
 420                argv_array_pushv(out, cmd->argv);
 421        }
 422
 423        /*
 424         * If there are no '/' characters in the command then perform a path
 425         * lookup and use the resolved path as the command to exec.  If there
 426         * are '/' characters, we have exec attempt to invoke the command
 427         * directly.
 428         */
 429        if (!strchr(out->argv[1], '/')) {
 430                char *program = locate_in_PATH(out->argv[1]);
 431                if (program) {
 432                        free((char *)out->argv[1]);
 433                        out->argv[1] = program;
 434                } else {
 435                        argv_array_clear(out);
 436                        errno = ENOENT;
 437                        return -1;
 438                }
 439        }
 440
 441        return 0;
 442}
 443
 444static char **prep_childenv(const char *const *deltaenv)
 445{
 446        extern char **environ;
 447        char **childenv;
 448        struct string_list env = STRING_LIST_INIT_DUP;
 449        struct strbuf key = STRBUF_INIT;
 450        const char *const *p;
 451        int i;
 452
 453        /* Construct a sorted string list consisting of the current environ */
 454        for (p = (const char *const *) environ; p && *p; p++) {
 455                const char *equals = strchr(*p, '=');
 456
 457                if (equals) {
 458                        strbuf_reset(&key);
 459                        strbuf_add(&key, *p, equals - *p);
 460                        string_list_append(&env, key.buf)->util = (void *) *p;
 461                } else {
 462                        string_list_append(&env, *p)->util = (void *) *p;
 463                }
 464        }
 465        string_list_sort(&env);
 466
 467        /* Merge in 'deltaenv' with the current environ */
 468        for (p = deltaenv; p && *p; p++) {
 469                const char *equals = strchr(*p, '=');
 470
 471                if (equals) {
 472                        /* ('key=value'), insert or replace entry */
 473                        strbuf_reset(&key);
 474                        strbuf_add(&key, *p, equals - *p);
 475                        string_list_insert(&env, key.buf)->util = (void *) *p;
 476                } else {
 477                        /* otherwise ('key') remove existing entry */
 478                        string_list_remove(&env, *p, 0);
 479                }
 480        }
 481
 482        /* Create an array of 'char *' to be used as the childenv */
 483        ALLOC_ARRAY(childenv, env.nr + 1);
 484        for (i = 0; i < env.nr; i++)
 485                childenv[i] = env.items[i].util;
 486        childenv[env.nr] = NULL;
 487
 488        string_list_clear(&env, 0);
 489        strbuf_release(&key);
 490        return childenv;
 491}
 492
 493struct atfork_state {
 494#ifndef NO_PTHREADS
 495        int cs;
 496#endif
 497        sigset_t old;
 498};
 499
 500#define CHECK_BUG(err, msg) \
 501        do { \
 502                int e = (err); \
 503                if (e) \
 504                        BUG("%s: %s", msg, strerror(e)); \
 505        } while(0)
 506
 507static void atfork_prepare(struct atfork_state *as)
 508{
 509        sigset_t all;
 510
 511        if (sigfillset(&all))
 512                die_errno("sigfillset");
 513#ifdef NO_PTHREADS
 514        if (sigprocmask(SIG_SETMASK, &all, &as->old))
 515                die_errno("sigprocmask");
 516#else
 517        CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
 518                "blocking all signals");
 519        CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
 520                "disabling cancellation");
 521#endif
 522}
 523
 524static void atfork_parent(struct atfork_state *as)
 525{
 526#ifdef NO_PTHREADS
 527        if (sigprocmask(SIG_SETMASK, &as->old, NULL))
 528                die_errno("sigprocmask");
 529#else
 530        CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
 531                "re-enabling cancellation");
 532        CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
 533                "restoring signal mask");
 534#endif
 535}
 536#endif /* GIT_WINDOWS_NATIVE */
 537
 538static inline void set_cloexec(int fd)
 539{
 540        int flags = fcntl(fd, F_GETFD);
 541        if (flags >= 0)
 542                fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 543}
 544
 545static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 546{
 547        int status, code = -1;
 548        pid_t waiting;
 549        int failed_errno = 0;
 550
 551        while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 552                ;       /* nothing */
 553        if (in_signal)
 554                return 0;
 555
 556        if (waiting < 0) {
 557                failed_errno = errno;
 558                error_errno("waitpid for %s failed", argv0);
 559        } else if (waiting != pid) {
 560                error("waitpid is confused (%s)", argv0);
 561        } else if (WIFSIGNALED(status)) {
 562                code = WTERMSIG(status);
 563                if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 564                        error("%s died of signal %d", argv0, code);
 565                /*
 566                 * This return value is chosen so that code & 0xff
 567                 * mimics the exit code that a POSIX shell would report for
 568                 * a program that died from this signal.
 569                 */
 570                code += 128;
 571        } else if (WIFEXITED(status)) {
 572                code = WEXITSTATUS(status);
 573        } else {
 574                error("waitpid is confused (%s)", argv0);
 575        }
 576
 577        clear_child_for_cleanup(pid);
 578
 579        errno = failed_errno;
 580        return code;
 581}
 582
 583static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
 584{
 585        struct string_list envs = STRING_LIST_INIT_DUP;
 586        const char *const *e;
 587        int i;
 588        int printed_unset = 0;
 589
 590        /* Last one wins, see run-command.c:prep_childenv() for context */
 591        for (e = deltaenv; e && *e; e++) {
 592                struct strbuf key = STRBUF_INIT;
 593                char *equals = strchr(*e, '=');
 594
 595                if (equals) {
 596                        strbuf_add(&key, *e, equals - *e);
 597                        string_list_insert(&envs, key.buf)->util = equals + 1;
 598                } else {
 599                        string_list_insert(&envs, *e)->util = NULL;
 600                }
 601                strbuf_release(&key);
 602        }
 603
 604        /* "unset X Y...;" */
 605        for (i = 0; i < envs.nr; i++) {
 606                const char *var = envs.items[i].string;
 607                const char *val = envs.items[i].util;
 608
 609                if (val || !getenv(var))
 610                        continue;
 611
 612                if (!printed_unset) {
 613                        strbuf_addstr(dst, " unset");
 614                        printed_unset = 1;
 615                }
 616                strbuf_addf(dst, " %s", var);
 617        }
 618        if (printed_unset)
 619                strbuf_addch(dst, ';');
 620
 621        /* ... followed by "A=B C=D ..." */
 622        for (i = 0; i < envs.nr; i++) {
 623                const char *var = envs.items[i].string;
 624                const char *val = envs.items[i].util;
 625                const char *oldval;
 626
 627                if (!val)
 628                        continue;
 629
 630                oldval = getenv(var);
 631                if (oldval && !strcmp(val, oldval))
 632                        continue;
 633
 634                strbuf_addf(dst, " %s=", var);
 635                sq_quote_buf_pretty(dst, val);
 636        }
 637        string_list_clear(&envs, 0);
 638}
 639
 640static void trace_run_command(const struct child_process *cp)
 641{
 642        struct strbuf buf = STRBUF_INIT;
 643
 644        if (!trace_want(&trace_default_key))
 645                return;
 646
 647        strbuf_addstr(&buf, "trace: run_command:");
 648        if (cp->dir) {
 649                strbuf_addstr(&buf, " cd ");
 650                sq_quote_buf_pretty(&buf, cp->dir);
 651                strbuf_addch(&buf, ';');
 652        }
 653        /*
 654         * The caller is responsible for initializing cp->env from
 655         * cp->env_array if needed. We only check one place.
 656         */
 657        if (cp->env)
 658                trace_add_env(&buf, cp->env);
 659        if (cp->git_cmd)
 660                strbuf_addstr(&buf, " git");
 661        sq_quote_argv_pretty(&buf, cp->argv);
 662
 663        trace_printf("%s", buf.buf);
 664        strbuf_release(&buf);
 665}
 666
 667int start_command(struct child_process *cmd)
 668{
 669        int need_in, need_out, need_err;
 670        int fdin[2], fdout[2], fderr[2];
 671        int failed_errno;
 672        char *str;
 673
 674        if (!cmd->argv)
 675                cmd->argv = cmd->args.argv;
 676        if (!cmd->env)
 677                cmd->env = cmd->env_array.argv;
 678
 679        /*
 680         * In case of errors we must keep the promise to close FDs
 681         * that have been passed in via ->in and ->out.
 682         */
 683
 684        need_in = !cmd->no_stdin && cmd->in < 0;
 685        if (need_in) {
 686                if (pipe(fdin) < 0) {
 687                        failed_errno = errno;
 688                        if (cmd->out > 0)
 689                                close(cmd->out);
 690                        str = "standard input";
 691                        goto fail_pipe;
 692                }
 693                cmd->in = fdin[1];
 694        }
 695
 696        need_out = !cmd->no_stdout
 697                && !cmd->stdout_to_stderr
 698                && cmd->out < 0;
 699        if (need_out) {
 700                if (pipe(fdout) < 0) {
 701                        failed_errno = errno;
 702                        if (need_in)
 703                                close_pair(fdin);
 704                        else if (cmd->in)
 705                                close(cmd->in);
 706                        str = "standard output";
 707                        goto fail_pipe;
 708                }
 709                cmd->out = fdout[0];
 710        }
 711
 712        need_err = !cmd->no_stderr && cmd->err < 0;
 713        if (need_err) {
 714                if (pipe(fderr) < 0) {
 715                        failed_errno = errno;
 716                        if (need_in)
 717                                close_pair(fdin);
 718                        else if (cmd->in)
 719                                close(cmd->in);
 720                        if (need_out)
 721                                close_pair(fdout);
 722                        else if (cmd->out)
 723                                close(cmd->out);
 724                        str = "standard error";
 725fail_pipe:
 726                        error("cannot create %s pipe for %s: %s",
 727                                str, cmd->argv[0], strerror(failed_errno));
 728                        child_process_clear(cmd);
 729                        errno = failed_errno;
 730                        return -1;
 731                }
 732                cmd->err = fderr[0];
 733        }
 734
 735        trace2_child_start(cmd);
 736        trace_run_command(cmd);
 737
 738        fflush(NULL);
 739
 740#ifndef GIT_WINDOWS_NATIVE
 741{
 742        int notify_pipe[2];
 743        int null_fd = -1;
 744        char **childenv;
 745        struct argv_array argv = ARGV_ARRAY_INIT;
 746        struct child_err cerr;
 747        struct atfork_state as;
 748
 749        if (prepare_cmd(&argv, cmd) < 0) {
 750                failed_errno = errno;
 751                cmd->pid = -1;
 752                if (!cmd->silent_exec_failure)
 753                        error_errno("cannot run %s", cmd->argv[0]);
 754                goto end_of_spawn;
 755        }
 756
 757        if (pipe(notify_pipe))
 758                notify_pipe[0] = notify_pipe[1] = -1;
 759
 760        if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
 761                null_fd = open("/dev/null", O_RDWR | O_CLOEXEC);
 762                if (null_fd < 0)
 763                        die_errno(_("open /dev/null failed"));
 764                set_cloexec(null_fd);
 765        }
 766
 767        childenv = prep_childenv(cmd->env);
 768        atfork_prepare(&as);
 769
 770        /*
 771         * NOTE: In order to prevent deadlocking when using threads special
 772         * care should be taken with the function calls made in between the
 773         * fork() and exec() calls.  No calls should be made to functions which
 774         * require acquiring a lock (e.g. malloc) as the lock could have been
 775         * held by another thread at the time of forking, causing the lock to
 776         * never be released in the child process.  This means only
 777         * Async-Signal-Safe functions are permitted in the child.
 778         */
 779        cmd->pid = fork();
 780        failed_errno = errno;
 781        if (!cmd->pid) {
 782                int sig;
 783                /*
 784                 * Ensure the default die/error/warn routines do not get
 785                 * called, they can take stdio locks and malloc.
 786                 */
 787                set_die_routine(child_die_fn);
 788                set_error_routine(child_error_fn);
 789                set_warn_routine(child_warn_fn);
 790
 791                close(notify_pipe[0]);
 792                set_cloexec(notify_pipe[1]);
 793                child_notifier = notify_pipe[1];
 794
 795                if (cmd->no_stdin)
 796                        child_dup2(null_fd, 0);
 797                else if (need_in) {
 798                        child_dup2(fdin[0], 0);
 799                        child_close_pair(fdin);
 800                } else if (cmd->in) {
 801                        child_dup2(cmd->in, 0);
 802                        child_close(cmd->in);
 803                }
 804
 805                if (cmd->no_stderr)
 806                        child_dup2(null_fd, 2);
 807                else if (need_err) {
 808                        child_dup2(fderr[1], 2);
 809                        child_close_pair(fderr);
 810                } else if (cmd->err > 1) {
 811                        child_dup2(cmd->err, 2);
 812                        child_close(cmd->err);
 813                }
 814
 815                if (cmd->no_stdout)
 816                        child_dup2(null_fd, 1);
 817                else if (cmd->stdout_to_stderr)
 818                        child_dup2(2, 1);
 819                else if (need_out) {
 820                        child_dup2(fdout[1], 1);
 821                        child_close_pair(fdout);
 822                } else if (cmd->out > 1) {
 823                        child_dup2(cmd->out, 1);
 824                        child_close(cmd->out);
 825                }
 826
 827                if (cmd->dir && chdir(cmd->dir))
 828                        child_die(CHILD_ERR_CHDIR);
 829
 830                /*
 831                 * restore default signal handlers here, in case
 832                 * we catch a signal right before execve below
 833                 */
 834                for (sig = 1; sig < NSIG; sig++) {
 835                        /* ignored signals get reset to SIG_DFL on execve */
 836                        if (signal(sig, SIG_DFL) == SIG_IGN)
 837                                signal(sig, SIG_IGN);
 838                }
 839
 840                if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
 841                        child_die(CHILD_ERR_SIGPROCMASK);
 842
 843                /*
 844                 * Attempt to exec using the command and arguments starting at
 845                 * argv.argv[1].  argv.argv[0] contains SHELL_PATH which will
 846                 * be used in the event exec failed with ENOEXEC at which point
 847                 * we will try to interpret the command using 'sh'.
 848                 */
 849                execve(argv.argv[1], (char *const *) argv.argv + 1,
 850                       (char *const *) childenv);
 851                if (errno == ENOEXEC)
 852                        execve(argv.argv[0], (char *const *) argv.argv,
 853                               (char *const *) childenv);
 854
 855                if (errno == ENOENT) {
 856                        if (cmd->silent_exec_failure)
 857                                child_die(CHILD_ERR_SILENT);
 858                        child_die(CHILD_ERR_ENOENT);
 859                } else {
 860                        child_die(CHILD_ERR_ERRNO);
 861                }
 862        }
 863        atfork_parent(&as);
 864        if (cmd->pid < 0)
 865                error_errno("cannot fork() for %s", cmd->argv[0]);
 866        else if (cmd->clean_on_exit)
 867                mark_child_for_cleanup(cmd->pid, cmd);
 868
 869        /*
 870         * Wait for child's exec. If the exec succeeds (or if fork()
 871         * failed), EOF is seen immediately by the parent. Otherwise, the
 872         * child process sends a child_err struct.
 873         * Note that use of this infrastructure is completely advisory,
 874         * therefore, we keep error checks minimal.
 875         */
 876        close(notify_pipe[1]);
 877        if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
 878                /*
 879                 * At this point we know that fork() succeeded, but exec()
 880                 * failed. Errors have been reported to our stderr.
 881                 */
 882                wait_or_whine(cmd->pid, cmd->argv[0], 0);
 883                child_err_spew(cmd, &cerr);
 884                failed_errno = errno;
 885                cmd->pid = -1;
 886        }
 887        close(notify_pipe[0]);
 888
 889        if (null_fd >= 0)
 890                close(null_fd);
 891        argv_array_clear(&argv);
 892        free(childenv);
 893}
 894end_of_spawn:
 895
 896#else
 897{
 898        int fhin = 0, fhout = 1, fherr = 2;
 899        const char **sargv = cmd->argv;
 900        struct argv_array nargv = ARGV_ARRAY_INIT;
 901
 902        if (cmd->no_stdin)
 903                fhin = open("/dev/null", O_RDWR);
 904        else if (need_in)
 905                fhin = dup(fdin[0]);
 906        else if (cmd->in)
 907                fhin = dup(cmd->in);
 908
 909        if (cmd->no_stderr)
 910                fherr = open("/dev/null", O_RDWR);
 911        else if (need_err)
 912                fherr = dup(fderr[1]);
 913        else if (cmd->err > 2)
 914                fherr = dup(cmd->err);
 915
 916        if (cmd->no_stdout)
 917                fhout = open("/dev/null", O_RDWR);
 918        else if (cmd->stdout_to_stderr)
 919                fhout = dup(fherr);
 920        else if (need_out)
 921                fhout = dup(fdout[1]);
 922        else if (cmd->out > 1)
 923                fhout = dup(cmd->out);
 924
 925        if (cmd->git_cmd)
 926                cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 927        else if (cmd->use_shell)
 928                cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 929
 930        cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 931                        cmd->dir, fhin, fhout, fherr);
 932        failed_errno = errno;
 933        if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 934                error_errno("cannot spawn %s", cmd->argv[0]);
 935        if (cmd->clean_on_exit && cmd->pid >= 0)
 936                mark_child_for_cleanup(cmd->pid, cmd);
 937
 938        argv_array_clear(&nargv);
 939        cmd->argv = sargv;
 940        if (fhin != 0)
 941                close(fhin);
 942        if (fhout != 1)
 943                close(fhout);
 944        if (fherr != 2)
 945                close(fherr);
 946}
 947#endif
 948
 949        if (cmd->pid < 0) {
 950                trace2_child_exit(cmd, -1);
 951
 952                if (need_in)
 953                        close_pair(fdin);
 954                else if (cmd->in)
 955                        close(cmd->in);
 956                if (need_out)
 957                        close_pair(fdout);
 958                else if (cmd->out)
 959                        close(cmd->out);
 960                if (need_err)
 961                        close_pair(fderr);
 962                else if (cmd->err)
 963                        close(cmd->err);
 964                child_process_clear(cmd);
 965                errno = failed_errno;
 966                return -1;
 967        }
 968
 969        if (need_in)
 970                close(fdin[0]);
 971        else if (cmd->in)
 972                close(cmd->in);
 973
 974        if (need_out)
 975                close(fdout[1]);
 976        else if (cmd->out)
 977                close(cmd->out);
 978
 979        if (need_err)
 980                close(fderr[1]);
 981        else if (cmd->err)
 982                close(cmd->err);
 983
 984        return 0;
 985}
 986
 987int finish_command(struct child_process *cmd)
 988{
 989        int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 990        trace2_child_exit(cmd, ret);
 991        child_process_clear(cmd);
 992        return ret;
 993}
 994
 995int finish_command_in_signal(struct child_process *cmd)
 996{
 997        int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
 998        trace2_child_exit(cmd, ret);
 999        return ret;
1000}
1001
1002
1003int run_command(struct child_process *cmd)
1004{
1005        int code;
1006
1007        if (cmd->out < 0 || cmd->err < 0)
1008                BUG("run_command with a pipe can cause deadlock");
1009
1010        code = start_command(cmd);
1011        if (code)
1012                return code;
1013        return finish_command(cmd);
1014}
1015
1016int run_command_v_opt(const char **argv, int opt)
1017{
1018        return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
1019}
1020
1021int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
1022{
1023        return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
1024}
1025
1026int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
1027{
1028        return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
1029}
1030
1031int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
1032                                 const char *const *env, const char *tr2_class)
1033{
1034        struct child_process cmd = CHILD_PROCESS_INIT;
1035        cmd.argv = argv;
1036        cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
1037        cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
1038        cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
1039        cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
1040        cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
1041        cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
1042        cmd.dir = dir;
1043        cmd.env = env;
1044        cmd.trace2_child_class = tr2_class;
1045        return run_command(&cmd);
1046}
1047
1048#ifndef NO_PTHREADS
1049static pthread_t main_thread;
1050static int main_thread_set;
1051static pthread_key_t async_key;
1052static pthread_key_t async_die_counter;
1053
1054static void *run_thread(void *data)
1055{
1056        struct async *async = data;
1057        intptr_t ret;
1058
1059        if (async->isolate_sigpipe) {
1060                sigset_t mask;
1061                sigemptyset(&mask);
1062                sigaddset(&mask, SIGPIPE);
1063                if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
1064                        ret = error("unable to block SIGPIPE in async thread");
1065                        return (void *)ret;
1066                }
1067        }
1068
1069        pthread_setspecific(async_key, async);
1070        ret = async->proc(async->proc_in, async->proc_out, async->data);
1071        return (void *)ret;
1072}
1073
1074static NORETURN void die_async(const char *err, va_list params)
1075{
1076        vreportf("fatal: ", err, params);
1077
1078        if (in_async()) {
1079                struct async *async = pthread_getspecific(async_key);
1080                if (async->proc_in >= 0)
1081                        close(async->proc_in);
1082                if (async->proc_out >= 0)
1083                        close(async->proc_out);
1084                pthread_exit((void *)128);
1085        }
1086
1087        exit(128);
1088}
1089
1090static int async_die_is_recursing(void)
1091{
1092        void *ret = pthread_getspecific(async_die_counter);
1093        pthread_setspecific(async_die_counter, (void *)1);
1094        return ret != NULL;
1095}
1096
1097int in_async(void)
1098{
1099        if (!main_thread_set)
1100                return 0; /* no asyncs started yet */
1101        return !pthread_equal(main_thread, pthread_self());
1102}
1103
1104static void NORETURN async_exit(int code)
1105{
1106        pthread_exit((void *)(intptr_t)code);
1107}
1108
1109#else
1110
1111static struct {
1112        void (**handlers)(void);
1113        size_t nr;
1114        size_t alloc;
1115} git_atexit_hdlrs;
1116
1117static int git_atexit_installed;
1118
1119static void git_atexit_dispatch(void)
1120{
1121        size_t i;
1122
1123        for (i=git_atexit_hdlrs.nr ; i ; i--)
1124                git_atexit_hdlrs.handlers[i-1]();
1125}
1126
1127static void git_atexit_clear(void)
1128{
1129        free(git_atexit_hdlrs.handlers);
1130        memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
1131        git_atexit_installed = 0;
1132}
1133
1134#undef atexit
1135int git_atexit(void (*handler)(void))
1136{
1137        ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
1138        git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
1139        if (!git_atexit_installed) {
1140                if (atexit(&git_atexit_dispatch))
1141                        return -1;
1142                git_atexit_installed = 1;
1143        }
1144        return 0;
1145}
1146#define atexit git_atexit
1147
1148static int process_is_async;
1149int in_async(void)
1150{
1151        return process_is_async;
1152}
1153
1154static void NORETURN async_exit(int code)
1155{
1156        exit(code);
1157}
1158
1159#endif
1160
1161void check_pipe(int err)
1162{
1163        if (err == EPIPE) {
1164                if (in_async())
1165                        async_exit(141);
1166
1167                signal(SIGPIPE, SIG_DFL);
1168                raise(SIGPIPE);
1169                /* Should never happen, but just in case... */
1170                exit(141);
1171        }
1172}
1173
1174int start_async(struct async *async)
1175{
1176        int need_in, need_out;
1177        int fdin[2], fdout[2];
1178        int proc_in, proc_out;
1179
1180        need_in = async->in < 0;
1181        if (need_in) {
1182                if (pipe(fdin) < 0) {
1183                        if (async->out > 0)
1184                                close(async->out);
1185                        return error_errno("cannot create pipe");
1186                }
1187                async->in = fdin[1];
1188        }
1189
1190        need_out = async->out < 0;
1191        if (need_out) {
1192                if (pipe(fdout) < 0) {
1193                        if (need_in)
1194                                close_pair(fdin);
1195                        else if (async->in)
1196                                close(async->in);
1197                        return error_errno("cannot create pipe");
1198                }
1199                async->out = fdout[0];
1200        }
1201
1202        if (need_in)
1203                proc_in = fdin[0];
1204        else if (async->in)
1205                proc_in = async->in;
1206        else
1207                proc_in = -1;
1208
1209        if (need_out)
1210                proc_out = fdout[1];
1211        else if (async->out)
1212                proc_out = async->out;
1213        else
1214                proc_out = -1;
1215
1216#ifdef NO_PTHREADS
1217        /* Flush stdio before fork() to avoid cloning buffers */
1218        fflush(NULL);
1219
1220        async->pid = fork();
1221        if (async->pid < 0) {
1222                error_errno("fork (async) failed");
1223                goto error;
1224        }
1225        if (!async->pid) {
1226                if (need_in)
1227                        close(fdin[1]);
1228                if (need_out)
1229                        close(fdout[0]);
1230                git_atexit_clear();
1231                process_is_async = 1;
1232                exit(!!async->proc(proc_in, proc_out, async->data));
1233        }
1234
1235        mark_child_for_cleanup(async->pid, NULL);
1236
1237        if (need_in)
1238                close(fdin[0]);
1239        else if (async->in)
1240                close(async->in);
1241
1242        if (need_out)
1243                close(fdout[1]);
1244        else if (async->out)
1245                close(async->out);
1246#else
1247        if (!main_thread_set) {
1248                /*
1249                 * We assume that the first time that start_async is called
1250                 * it is from the main thread.
1251                 */
1252                main_thread_set = 1;
1253                main_thread = pthread_self();
1254                pthread_key_create(&async_key, NULL);
1255                pthread_key_create(&async_die_counter, NULL);
1256                set_die_routine(die_async);
1257                set_die_is_recursing_routine(async_die_is_recursing);
1258        }
1259
1260        if (proc_in >= 0)
1261                set_cloexec(proc_in);
1262        if (proc_out >= 0)
1263                set_cloexec(proc_out);
1264        async->proc_in = proc_in;
1265        async->proc_out = proc_out;
1266        {
1267                int err = pthread_create(&async->tid, NULL, run_thread, async);
1268                if (err) {
1269                        error(_("cannot create async thread: %s"), strerror(err));
1270                        goto error;
1271                }
1272        }
1273#endif
1274        return 0;
1275
1276error:
1277        if (need_in)
1278                close_pair(fdin);
1279        else if (async->in)
1280                close(async->in);
1281
1282        if (need_out)
1283                close_pair(fdout);
1284        else if (async->out)
1285                close(async->out);
1286        return -1;
1287}
1288
1289int finish_async(struct async *async)
1290{
1291#ifdef NO_PTHREADS
1292        return wait_or_whine(async->pid, "child process", 0);
1293#else
1294        void *ret = (void *)(intptr_t)(-1);
1295
1296        if (pthread_join(async->tid, &ret))
1297                error("pthread_join failed");
1298        return (int)(intptr_t)ret;
1299#endif
1300}
1301
1302int async_with_fork(void)
1303{
1304#ifdef NO_PTHREADS
1305        return 1;
1306#else
1307        return 0;
1308#endif
1309}
1310
1311const char *find_hook(const char *name)
1312{
1313        static struct strbuf path = STRBUF_INIT;
1314
1315        strbuf_reset(&path);
1316        strbuf_git_path(&path, "hooks/%s", name);
1317        if (access(path.buf, X_OK) < 0) {
1318                int err = errno;
1319
1320#ifdef STRIP_EXTENSION
1321                strbuf_addstr(&path, STRIP_EXTENSION);
1322                if (access(path.buf, X_OK) >= 0)
1323                        return path.buf;
1324                if (errno == EACCES)
1325                        err = errno;
1326#endif
1327
1328                if (err == EACCES && advice_ignored_hook) {
1329                        static struct string_list advise_given = STRING_LIST_INIT_DUP;
1330
1331                        if (!string_list_lookup(&advise_given, name)) {
1332                                string_list_insert(&advise_given, name);
1333                                advise(_("The '%s' hook was ignored because "
1334                                         "it's not set as executable.\n"
1335                                         "You can disable this warning with "
1336                                         "`git config advice.ignoredHook false`."),
1337                                       path.buf);
1338                        }
1339                }
1340                return NULL;
1341        }
1342        return path.buf;
1343}
1344
1345int run_hook_ve(const char *const *env, const char *name, va_list args)
1346{
1347        struct child_process hook = CHILD_PROCESS_INIT;
1348        const char *p;
1349
1350        p = find_hook(name);
1351        if (!p)
1352                return 0;
1353
1354        argv_array_push(&hook.args, p);
1355        while ((p = va_arg(args, const char *)))
1356                argv_array_push(&hook.args, p);
1357        hook.env = env;
1358        hook.no_stdin = 1;
1359        hook.stdout_to_stderr = 1;
1360        hook.trace2_hook_name = name;
1361
1362        return run_command(&hook);
1363}
1364
1365int run_hook_le(const char *const *env, const char *name, ...)
1366{
1367        va_list args;
1368        int ret;
1369
1370        va_start(args, name);
1371        ret = run_hook_ve(env, name, args);
1372        va_end(args);
1373
1374        return ret;
1375}
1376
1377struct io_pump {
1378        /* initialized by caller */
1379        int fd;
1380        int type; /* POLLOUT or POLLIN */
1381        union {
1382                struct {
1383                        const char *buf;
1384                        size_t len;
1385                } out;
1386                struct {
1387                        struct strbuf *buf;
1388                        size_t hint;
1389                } in;
1390        } u;
1391
1392        /* returned by pump_io */
1393        int error; /* 0 for success, otherwise errno */
1394
1395        /* internal use */
1396        struct pollfd *pfd;
1397};
1398
1399static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
1400{
1401        int pollsize = 0;
1402        int i;
1403
1404        for (i = 0; i < nr; i++) {
1405                struct io_pump *io = &slots[i];
1406                if (io->fd < 0)
1407                        continue;
1408                pfd[pollsize].fd = io->fd;
1409                pfd[pollsize].events = io->type;
1410                io->pfd = &pfd[pollsize++];
1411        }
1412
1413        if (!pollsize)
1414                return 0;
1415
1416        if (poll(pfd, pollsize, -1) < 0) {
1417                if (errno == EINTR)
1418                        return 1;
1419                die_errno("poll failed");
1420        }
1421
1422        for (i = 0; i < nr; i++) {
1423                struct io_pump *io = &slots[i];
1424
1425                if (io->fd < 0)
1426                        continue;
1427
1428                if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
1429                        continue;
1430
1431                if (io->type == POLLOUT) {
1432                        ssize_t len = xwrite(io->fd,
1433                                             io->u.out.buf, io->u.out.len);
1434                        if (len < 0) {
1435                                io->error = errno;
1436                                close(io->fd);
1437                                io->fd = -1;
1438                        } else {
1439                                io->u.out.buf += len;
1440                                io->u.out.len -= len;
1441                                if (!io->u.out.len) {
1442                                        close(io->fd);
1443                                        io->fd = -1;
1444                                }
1445                        }
1446                }
1447
1448                if (io->type == POLLIN) {
1449                        ssize_t len = strbuf_read_once(io->u.in.buf,
1450                                                       io->fd, io->u.in.hint);
1451                        if (len < 0)
1452                                io->error = errno;
1453                        if (len <= 0) {
1454                                close(io->fd);
1455                                io->fd = -1;
1456                        }
1457                }
1458        }
1459
1460        return 1;
1461}
1462
1463static int pump_io(struct io_pump *slots, int nr)
1464{
1465        struct pollfd *pfd;
1466        int i;
1467
1468        for (i = 0; i < nr; i++)
1469                slots[i].error = 0;
1470
1471        ALLOC_ARRAY(pfd, nr);
1472        while (pump_io_round(slots, nr, pfd))
1473                ; /* nothing */
1474        free(pfd);
1475
1476        /* There may be multiple errno values, so just pick the first. */
1477        for (i = 0; i < nr; i++) {
1478                if (slots[i].error) {
1479                        errno = slots[i].error;
1480                        return -1;
1481                }
1482        }
1483        return 0;
1484}
1485
1486
1487int pipe_command(struct child_process *cmd,
1488                 const char *in, size_t in_len,
1489                 struct strbuf *out, size_t out_hint,
1490                 struct strbuf *err, size_t err_hint)
1491{
1492        struct io_pump io[3];
1493        int nr = 0;
1494
1495        if (in)
1496                cmd->in = -1;
1497        if (out)
1498                cmd->out = -1;
1499        if (err)
1500                cmd->err = -1;
1501
1502        if (start_command(cmd) < 0)
1503                return -1;
1504
1505        if (in) {
1506                io[nr].fd = cmd->in;
1507                io[nr].type = POLLOUT;
1508                io[nr].u.out.buf = in;
1509                io[nr].u.out.len = in_len;
1510                nr++;
1511        }
1512        if (out) {
1513                io[nr].fd = cmd->out;
1514                io[nr].type = POLLIN;
1515                io[nr].u.in.buf = out;
1516                io[nr].u.in.hint = out_hint;
1517                nr++;
1518        }
1519        if (err) {
1520                io[nr].fd = cmd->err;
1521                io[nr].type = POLLIN;
1522                io[nr].u.in.buf = err;
1523                io[nr].u.in.hint = err_hint;
1524                nr++;
1525        }
1526
1527        if (pump_io(io, nr) < 0) {
1528                finish_command(cmd); /* throw away exit code */
1529                return -1;
1530        }
1531
1532        return finish_command(cmd);
1533}
1534
1535enum child_state {
1536        GIT_CP_FREE,
1537        GIT_CP_WORKING,
1538        GIT_CP_WAIT_CLEANUP,
1539};
1540
1541struct parallel_processes {
1542        void *data;
1543
1544        int max_processes;
1545        int nr_processes;
1546
1547        get_next_task_fn get_next_task;
1548        start_failure_fn start_failure;
1549        task_finished_fn task_finished;
1550
1551        struct {
1552                enum child_state state;
1553                struct child_process process;
1554                struct strbuf err;
1555                void *data;
1556        } *children;
1557        /*
1558         * The struct pollfd is logically part of *children,
1559         * but the system call expects it as its own array.
1560         */
1561        struct pollfd *pfd;
1562
1563        unsigned shutdown : 1;
1564
1565        int output_owner;
1566        struct strbuf buffered_output; /* of finished children */
1567};
1568
1569static int default_start_failure(struct strbuf *out,
1570                                 void *pp_cb,
1571                                 void *pp_task_cb)
1572{
1573        return 0;
1574}
1575
1576static int default_task_finished(int result,
1577                                 struct strbuf *out,
1578                                 void *pp_cb,
1579                                 void *pp_task_cb)
1580{
1581        return 0;
1582}
1583
1584static void kill_children(struct parallel_processes *pp, int signo)
1585{
1586        int i, n = pp->max_processes;
1587
1588        for (i = 0; i < n; i++)
1589                if (pp->children[i].state == GIT_CP_WORKING)
1590                        kill(pp->children[i].process.pid, signo);
1591}
1592
1593static struct parallel_processes *pp_for_signal;
1594
1595static void handle_children_on_signal(int signo)
1596{
1597        kill_children(pp_for_signal, signo);
1598        sigchain_pop(signo);
1599        raise(signo);
1600}
1601
1602static void pp_init(struct parallel_processes *pp,
1603                    int n,
1604                    get_next_task_fn get_next_task,
1605                    start_failure_fn start_failure,
1606                    task_finished_fn task_finished,
1607                    void *data)
1608{
1609        int i;
1610
1611        if (n < 1)
1612                n = online_cpus();
1613
1614        pp->max_processes = n;
1615
1616        trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
1617
1618        pp->data = data;
1619        if (!get_next_task)
1620                BUG("you need to specify a get_next_task function");
1621        pp->get_next_task = get_next_task;
1622
1623        pp->start_failure = start_failure ? start_failure : default_start_failure;
1624        pp->task_finished = task_finished ? task_finished : default_task_finished;
1625
1626        pp->nr_processes = 0;
1627        pp->output_owner = 0;
1628        pp->shutdown = 0;
1629        pp->children = xcalloc(n, sizeof(*pp->children));
1630        pp->pfd = xcalloc(n, sizeof(*pp->pfd));
1631        strbuf_init(&pp->buffered_output, 0);
1632
1633        for (i = 0; i < n; i++) {
1634                strbuf_init(&pp->children[i].err, 0);
1635                child_process_init(&pp->children[i].process);
1636                pp->pfd[i].events = POLLIN | POLLHUP;
1637                pp->pfd[i].fd = -1;
1638        }
1639
1640        pp_for_signal = pp;
1641        sigchain_push_common(handle_children_on_signal);
1642}
1643
1644static void pp_cleanup(struct parallel_processes *pp)
1645{
1646        int i;
1647
1648        trace_printf("run_processes_parallel: done");
1649        for (i = 0; i < pp->max_processes; i++) {
1650                strbuf_release(&pp->children[i].err);
1651                child_process_clear(&pp->children[i].process);
1652        }
1653
1654        free(pp->children);
1655        free(pp->pfd);
1656
1657        /*
1658         * When get_next_task added messages to the buffer in its last
1659         * iteration, the buffered output is non empty.
1660         */
1661        strbuf_write(&pp->buffered_output, stderr);
1662        strbuf_release(&pp->buffered_output);
1663
1664        sigchain_pop_common();
1665}
1666
1667/* returns
1668 *  0 if a new task was started.
1669 *  1 if no new jobs was started (get_next_task ran out of work, non critical
1670 *    problem with starting a new command)
1671 * <0 no new job was started, user wishes to shutdown early. Use negative code
1672 *    to signal the children.
1673 */
1674static int pp_start_one(struct parallel_processes *pp)
1675{
1676        int i, code;
1677
1678        for (i = 0; i < pp->max_processes; i++)
1679                if (pp->children[i].state == GIT_CP_FREE)
1680                        break;
1681        if (i == pp->max_processes)
1682                BUG("bookkeeping is hard");
1683
1684        code = pp->get_next_task(&pp->children[i].process,
1685                                 &pp->children[i].err,
1686                                 pp->data,
1687                                 &pp->children[i].data);
1688        if (!code) {
1689                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1690                strbuf_reset(&pp->children[i].err);
1691                return 1;
1692        }
1693        pp->children[i].process.err = -1;
1694        pp->children[i].process.stdout_to_stderr = 1;
1695        pp->children[i].process.no_stdin = 1;
1696
1697        if (start_command(&pp->children[i].process)) {
1698                code = pp->start_failure(&pp->children[i].err,
1699                                         pp->data,
1700                                         pp->children[i].data);
1701                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1702                strbuf_reset(&pp->children[i].err);
1703                if (code)
1704                        pp->shutdown = 1;
1705                return code;
1706        }
1707
1708        pp->nr_processes++;
1709        pp->children[i].state = GIT_CP_WORKING;
1710        pp->pfd[i].fd = pp->children[i].process.err;
1711        return 0;
1712}
1713
1714static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1715{
1716        int i;
1717
1718        while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1719                if (errno == EINTR)
1720                        continue;
1721                pp_cleanup(pp);
1722                die_errno("poll");
1723        }
1724
1725        /* Buffer output from all pipes. */
1726        for (i = 0; i < pp->max_processes; i++) {
1727                if (pp->children[i].state == GIT_CP_WORKING &&
1728                    pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1729                        int n = strbuf_read_once(&pp->children[i].err,
1730                                                 pp->children[i].process.err, 0);
1731                        if (n == 0) {
1732                                close(pp->children[i].process.err);
1733                                pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1734                        } else if (n < 0)
1735                                if (errno != EAGAIN)
1736                                        die_errno("read");
1737                }
1738        }
1739}
1740
1741static void pp_output(struct parallel_processes *pp)
1742{
1743        int i = pp->output_owner;
1744        if (pp->children[i].state == GIT_CP_WORKING &&
1745            pp->children[i].err.len) {
1746                strbuf_write(&pp->children[i].err, stderr);
1747                strbuf_reset(&pp->children[i].err);
1748        }
1749}
1750
1751static int pp_collect_finished(struct parallel_processes *pp)
1752{
1753        int i, code;
1754        int n = pp->max_processes;
1755        int result = 0;
1756
1757        while (pp->nr_processes > 0) {
1758                for (i = 0; i < pp->max_processes; i++)
1759                        if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1760                                break;
1761                if (i == pp->max_processes)
1762                        break;
1763
1764                code = finish_command(&pp->children[i].process);
1765
1766                code = pp->task_finished(code,
1767                                         &pp->children[i].err, pp->data,
1768                                         pp->children[i].data);
1769
1770                if (code)
1771                        result = code;
1772                if (code < 0)
1773                        break;
1774
1775                pp->nr_processes--;
1776                pp->children[i].state = GIT_CP_FREE;
1777                pp->pfd[i].fd = -1;
1778                child_process_init(&pp->children[i].process);
1779
1780                if (i != pp->output_owner) {
1781                        strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1782                        strbuf_reset(&pp->children[i].err);
1783                } else {
1784                        strbuf_write(&pp->children[i].err, stderr);
1785                        strbuf_reset(&pp->children[i].err);
1786
1787                        /* Output all other finished child processes */
1788                        strbuf_write(&pp->buffered_output, stderr);
1789                        strbuf_reset(&pp->buffered_output);
1790
1791                        /*
1792                         * Pick next process to output live.
1793                         * NEEDSWORK:
1794                         * For now we pick it randomly by doing a round
1795                         * robin. Later we may want to pick the one with
1796                         * the most output or the longest or shortest
1797                         * running process time.
1798                         */
1799                        for (i = 0; i < n; i++)
1800                                if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1801                                        break;
1802                        pp->output_owner = (pp->output_owner + i) % n;
1803                }
1804        }
1805        return result;
1806}
1807
1808int run_processes_parallel(int n,
1809                           get_next_task_fn get_next_task,
1810                           start_failure_fn start_failure,
1811                           task_finished_fn task_finished,
1812                           void *pp_cb)
1813{
1814        int i, code;
1815        int output_timeout = 100;
1816        int spawn_cap = 4;
1817        struct parallel_processes pp;
1818
1819        pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1820        while (1) {
1821                for (i = 0;
1822                    i < spawn_cap && !pp.shutdown &&
1823                    pp.nr_processes < pp.max_processes;
1824                    i++) {
1825                        code = pp_start_one(&pp);
1826                        if (!code)
1827                                continue;
1828                        if (code < 0) {
1829                                pp.shutdown = 1;
1830                                kill_children(&pp, -code);
1831                        }
1832                        break;
1833                }
1834                if (!pp.nr_processes)
1835                        break;
1836                pp_buffer_stderr(&pp, output_timeout);
1837                pp_output(&pp);
1838                code = pp_collect_finished(&pp);
1839                if (code) {
1840                        pp.shutdown = 1;
1841                        if (code < 0)
1842                                kill_children(&pp, -code);
1843                }
1844        }
1845
1846        pp_cleanup(&pp);
1847        return 0;
1848}
1849
1850int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
1851                               start_failure_fn start_failure,
1852                               task_finished_fn task_finished, void *pp_cb,
1853                               const char *tr2_category, const char *tr2_label)
1854{
1855        int result;
1856
1857        trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
1858                                   ((n < 1) ? online_cpus() : n));
1859
1860        result = run_processes_parallel(n, get_next_task, start_failure,
1861                                        task_finished, pp_cb);
1862
1863        trace2_region_leave(tr2_category, tr2_label, NULL);
1864
1865        return result;
1866}