Andrew's git / gitweb.git / run-command.c
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run-command.con commit MSVC: use shipped headers instead of fallback definitions (0ef60af)
   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
   9void child_process_init(struct child_process *child)
  10{
  11        memset(child, 0, sizeof(*child));
  12        argv_array_init(&child->args);
  13        argv_array_init(&child->env_array);
  14}
  15
  16void child_process_clear(struct child_process *child)
  17{
  18        argv_array_clear(&child->args);
  19        argv_array_clear(&child->env_array);
  20}
  21
  22struct child_to_clean {
  23        pid_t pid;
  24        struct child_to_clean *next;
  25};
  26static struct child_to_clean *children_to_clean;
  27static int installed_child_cleanup_handler;
  28
  29static void cleanup_children(int sig, int in_signal)
  30{
  31        while (children_to_clean) {
  32                struct child_to_clean *p = children_to_clean;
  33                children_to_clean = p->next;
  34                kill(p->pid, sig);
  35                if (!in_signal)
  36                        free(p);
  37        }
  38}
  39
  40static void cleanup_children_on_signal(int sig)
  41{
  42        cleanup_children(sig, 1);
  43        sigchain_pop(sig);
  44        raise(sig);
  45}
  46
  47static void cleanup_children_on_exit(void)
  48{
  49        cleanup_children(SIGTERM, 0);
  50}
  51
  52static void mark_child_for_cleanup(pid_t pid)
  53{
  54        struct child_to_clean *p = xmalloc(sizeof(*p));
  55        p->pid = pid;
  56        p->next = children_to_clean;
  57        children_to_clean = p;
  58
  59        if (!installed_child_cleanup_handler) {
  60                atexit(cleanup_children_on_exit);
  61                sigchain_push_common(cleanup_children_on_signal);
  62                installed_child_cleanup_handler = 1;
  63        }
  64}
  65
  66static void clear_child_for_cleanup(pid_t pid)
  67{
  68        struct child_to_clean **pp;
  69
  70        for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
  71                struct child_to_clean *clean_me = *pp;
  72
  73                if (clean_me->pid == pid) {
  74                        *pp = clean_me->next;
  75                        free(clean_me);
  76                        return;
  77                }
  78        }
  79}
  80
  81static inline void close_pair(int fd[2])
  82{
  83        close(fd[0]);
  84        close(fd[1]);
  85}
  86
  87#ifndef GIT_WINDOWS_NATIVE
  88static inline void dup_devnull(int to)
  89{
  90        int fd = open("/dev/null", O_RDWR);
  91        if (fd < 0)
  92                die_errno(_("open /dev/null failed"));
  93        if (dup2(fd, to) < 0)
  94                die_errno(_("dup2(%d,%d) failed"), fd, to);
  95        close(fd);
  96}
  97#endif
  98
  99static char *locate_in_PATH(const char *file)
 100{
 101        const char *p = getenv("PATH");
 102        struct strbuf buf = STRBUF_INIT;
 103
 104        if (!p || !*p)
 105                return NULL;
 106
 107        while (1) {
 108                const char *end = strchrnul(p, ':');
 109
 110                strbuf_reset(&buf);
 111
 112                /* POSIX specifies an empty entry as the current directory. */
 113                if (end != p) {
 114                        strbuf_add(&buf, p, end - p);
 115                        strbuf_addch(&buf, '/');
 116                }
 117                strbuf_addstr(&buf, file);
 118
 119                if (!access(buf.buf, F_OK))
 120                        return strbuf_detach(&buf, NULL);
 121
 122                if (!*end)
 123                        break;
 124                p = end + 1;
 125        }
 126
 127        strbuf_release(&buf);
 128        return NULL;
 129}
 130
 131static int exists_in_PATH(const char *file)
 132{
 133        char *r = locate_in_PATH(file);
 134        free(r);
 135        return r != NULL;
 136}
 137
 138int sane_execvp(const char *file, char * const argv[])
 139{
 140        if (!execvp(file, argv))
 141                return 0; /* cannot happen ;-) */
 142
 143        /*
 144         * When a command can't be found because one of the directories
 145         * listed in $PATH is unsearchable, execvp reports EACCES, but
 146         * careful usability testing (read: analysis of occasional bug
 147         * reports) reveals that "No such file or directory" is more
 148         * intuitive.
 149         *
 150         * We avoid commands with "/", because execvp will not do $PATH
 151         * lookups in that case.
 152         *
 153         * The reassignment of EACCES to errno looks like a no-op below,
 154         * but we need to protect against exists_in_PATH overwriting errno.
 155         */
 156        if (errno == EACCES && !strchr(file, '/'))
 157                errno = exists_in_PATH(file) ? EACCES : ENOENT;
 158        else if (errno == ENOTDIR && !strchr(file, '/'))
 159                errno = ENOENT;
 160        return -1;
 161}
 162
 163static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
 164{
 165        if (!argv[0])
 166                die("BUG: shell command is empty");
 167
 168        if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
 169#ifndef GIT_WINDOWS_NATIVE
 170                argv_array_push(out, SHELL_PATH);
 171#else
 172                argv_array_push(out, "sh");
 173#endif
 174                argv_array_push(out, "-c");
 175
 176                /*
 177                 * If we have no extra arguments, we do not even need to
 178                 * bother with the "$@" magic.
 179                 */
 180                if (!argv[1])
 181                        argv_array_push(out, argv[0]);
 182                else
 183                        argv_array_pushf(out, "%s \"$@\"", argv[0]);
 184        }
 185
 186        argv_array_pushv(out, argv);
 187        return out->argv;
 188}
 189
 190#ifndef GIT_WINDOWS_NATIVE
 191static int execv_shell_cmd(const char **argv)
 192{
 193        struct argv_array nargv = ARGV_ARRAY_INIT;
 194        prepare_shell_cmd(&nargv, argv);
 195        trace_argv_printf(nargv.argv, "trace: exec:");
 196        sane_execvp(nargv.argv[0], (char **)nargv.argv);
 197        argv_array_clear(&nargv);
 198        return -1;
 199}
 200#endif
 201
 202#ifndef GIT_WINDOWS_NATIVE
 203static int child_notifier = -1;
 204
 205static void notify_parent(void)
 206{
 207        /*
 208         * execvp failed.  If possible, we'd like to let start_command
 209         * know, so failures like ENOENT can be handled right away; but
 210         * otherwise, finish_command will still report the error.
 211         */
 212        xwrite(child_notifier, "", 1);
 213}
 214#endif
 215
 216static inline void set_cloexec(int fd)
 217{
 218        int flags = fcntl(fd, F_GETFD);
 219        if (flags >= 0)
 220                fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
 221}
 222
 223static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 224{
 225        int status, code = -1;
 226        pid_t waiting;
 227        int failed_errno = 0;
 228
 229        while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 230                ;       /* nothing */
 231        if (in_signal)
 232                return 0;
 233
 234        if (waiting < 0) {
 235                failed_errno = errno;
 236                error("waitpid for %s failed: %s", argv0, strerror(errno));
 237        } else if (waiting != pid) {
 238                error("waitpid is confused (%s)", argv0);
 239        } else if (WIFSIGNALED(status)) {
 240                code = WTERMSIG(status);
 241                if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 242                        error("%s died of signal %d", argv0, code);
 243                /*
 244                 * This return value is chosen so that code & 0xff
 245                 * mimics the exit code that a POSIX shell would report for
 246                 * a program that died from this signal.
 247                 */
 248                code += 128;
 249        } else if (WIFEXITED(status)) {
 250                code = WEXITSTATUS(status);
 251                /*
 252                 * Convert special exit code when execvp failed.
 253                 */
 254                if (code == 127) {
 255                        code = -1;
 256                        failed_errno = ENOENT;
 257                }
 258        } else {
 259                error("waitpid is confused (%s)", argv0);
 260        }
 261
 262        clear_child_for_cleanup(pid);
 263
 264        errno = failed_errno;
 265        return code;
 266}
 267
 268int start_command(struct child_process *cmd)
 269{
 270        int need_in, need_out, need_err;
 271        int fdin[2], fdout[2], fderr[2];
 272        int failed_errno;
 273        char *str;
 274
 275        if (!cmd->argv)
 276                cmd->argv = cmd->args.argv;
 277        if (!cmd->env)
 278                cmd->env = cmd->env_array.argv;
 279
 280        /*
 281         * In case of errors we must keep the promise to close FDs
 282         * that have been passed in via ->in and ->out.
 283         */
 284
 285        need_in = !cmd->no_stdin && cmd->in < 0;
 286        if (need_in) {
 287                if (pipe(fdin) < 0) {
 288                        failed_errno = errno;
 289                        if (cmd->out > 0)
 290                                close(cmd->out);
 291                        str = "standard input";
 292                        goto fail_pipe;
 293                }
 294                cmd->in = fdin[1];
 295        }
 296
 297        need_out = !cmd->no_stdout
 298                && !cmd->stdout_to_stderr
 299                && cmd->out < 0;
 300        if (need_out) {
 301                if (pipe(fdout) < 0) {
 302                        failed_errno = errno;
 303                        if (need_in)
 304                                close_pair(fdin);
 305                        else if (cmd->in)
 306                                close(cmd->in);
 307                        str = "standard output";
 308                        goto fail_pipe;
 309                }
 310                cmd->out = fdout[0];
 311        }
 312
 313        need_err = !cmd->no_stderr && cmd->err < 0;
 314        if (need_err) {
 315                if (pipe(fderr) < 0) {
 316                        failed_errno = errno;
 317                        if (need_in)
 318                                close_pair(fdin);
 319                        else if (cmd->in)
 320                                close(cmd->in);
 321                        if (need_out)
 322                                close_pair(fdout);
 323                        else if (cmd->out)
 324                                close(cmd->out);
 325                        str = "standard error";
 326fail_pipe:
 327                        error("cannot create %s pipe for %s: %s",
 328                                str, cmd->argv[0], strerror(failed_errno));
 329                        child_process_clear(cmd);
 330                        errno = failed_errno;
 331                        return -1;
 332                }
 333                cmd->err = fderr[0];
 334        }
 335
 336        trace_argv_printf(cmd->argv, "trace: run_command:");
 337        fflush(NULL);
 338
 339#ifndef GIT_WINDOWS_NATIVE
 340{
 341        int notify_pipe[2];
 342        if (pipe(notify_pipe))
 343                notify_pipe[0] = notify_pipe[1] = -1;
 344
 345        cmd->pid = fork();
 346        failed_errno = errno;
 347        if (!cmd->pid) {
 348                /*
 349                 * Redirect the channel to write syscall error messages to
 350                 * before redirecting the process's stderr so that all die()
 351                 * in subsequent call paths use the parent's stderr.
 352                 */
 353                if (cmd->no_stderr || need_err) {
 354                        int child_err = dup(2);
 355                        set_cloexec(child_err);
 356                        set_error_handle(fdopen(child_err, "w"));
 357                }
 358
 359                close(notify_pipe[0]);
 360                set_cloexec(notify_pipe[1]);
 361                child_notifier = notify_pipe[1];
 362                atexit(notify_parent);
 363
 364                if (cmd->no_stdin)
 365                        dup_devnull(0);
 366                else if (need_in) {
 367                        dup2(fdin[0], 0);
 368                        close_pair(fdin);
 369                } else if (cmd->in) {
 370                        dup2(cmd->in, 0);
 371                        close(cmd->in);
 372                }
 373
 374                if (cmd->no_stderr)
 375                        dup_devnull(2);
 376                else if (need_err) {
 377                        dup2(fderr[1], 2);
 378                        close_pair(fderr);
 379                } else if (cmd->err > 1) {
 380                        dup2(cmd->err, 2);
 381                        close(cmd->err);
 382                }
 383
 384                if (cmd->no_stdout)
 385                        dup_devnull(1);
 386                else if (cmd->stdout_to_stderr)
 387                        dup2(2, 1);
 388                else if (need_out) {
 389                        dup2(fdout[1], 1);
 390                        close_pair(fdout);
 391                } else if (cmd->out > 1) {
 392                        dup2(cmd->out, 1);
 393                        close(cmd->out);
 394                }
 395
 396                if (cmd->dir && chdir(cmd->dir))
 397                        die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 398                            cmd->dir);
 399                if (cmd->env) {
 400                        for (; *cmd->env; cmd->env++) {
 401                                if (strchr(*cmd->env, '='))
 402                                        putenv((char *)*cmd->env);
 403                                else
 404                                        unsetenv(*cmd->env);
 405                        }
 406                }
 407                if (cmd->git_cmd)
 408                        execv_git_cmd(cmd->argv);
 409                else if (cmd->use_shell)
 410                        execv_shell_cmd(cmd->argv);
 411                else
 412                        sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
 413                if (errno == ENOENT) {
 414                        if (!cmd->silent_exec_failure)
 415                                error("cannot run %s: %s", cmd->argv[0],
 416                                        strerror(ENOENT));
 417                        exit(127);
 418                } else {
 419                        die_errno("cannot exec '%s'", cmd->argv[0]);
 420                }
 421        }
 422        if (cmd->pid < 0)
 423                error("cannot fork() for %s: %s", cmd->argv[0],
 424                        strerror(errno));
 425        else if (cmd->clean_on_exit)
 426                mark_child_for_cleanup(cmd->pid);
 427
 428        /*
 429         * Wait for child's execvp. If the execvp succeeds (or if fork()
 430         * failed), EOF is seen immediately by the parent. Otherwise, the
 431         * child process sends a single byte.
 432         * Note that use of this infrastructure is completely advisory,
 433         * therefore, we keep error checks minimal.
 434         */
 435        close(notify_pipe[1]);
 436        if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 437                /*
 438                 * At this point we know that fork() succeeded, but execvp()
 439                 * failed. Errors have been reported to our stderr.
 440                 */
 441                wait_or_whine(cmd->pid, cmd->argv[0], 0);
 442                failed_errno = errno;
 443                cmd->pid = -1;
 444        }
 445        close(notify_pipe[0]);
 446}
 447#else
 448{
 449        int fhin = 0, fhout = 1, fherr = 2;
 450        const char **sargv = cmd->argv;
 451        struct argv_array nargv = ARGV_ARRAY_INIT;
 452
 453        if (cmd->no_stdin)
 454                fhin = open("/dev/null", O_RDWR);
 455        else if (need_in)
 456                fhin = dup(fdin[0]);
 457        else if (cmd->in)
 458                fhin = dup(cmd->in);
 459
 460        if (cmd->no_stderr)
 461                fherr = open("/dev/null", O_RDWR);
 462        else if (need_err)
 463                fherr = dup(fderr[1]);
 464        else if (cmd->err > 2)
 465                fherr = dup(cmd->err);
 466
 467        if (cmd->no_stdout)
 468                fhout = open("/dev/null", O_RDWR);
 469        else if (cmd->stdout_to_stderr)
 470                fhout = dup(fherr);
 471        else if (need_out)
 472                fhout = dup(fdout[1]);
 473        else if (cmd->out > 1)
 474                fhout = dup(cmd->out);
 475
 476        if (cmd->git_cmd)
 477                cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 478        else if (cmd->use_shell)
 479                cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 480
 481        cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 482                        cmd->dir, fhin, fhout, fherr);
 483        failed_errno = errno;
 484        if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 485                error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
 486        if (cmd->clean_on_exit && cmd->pid >= 0)
 487                mark_child_for_cleanup(cmd->pid);
 488
 489        argv_array_clear(&nargv);
 490        cmd->argv = sargv;
 491        if (fhin != 0)
 492                close(fhin);
 493        if (fhout != 1)
 494                close(fhout);
 495        if (fherr != 2)
 496                close(fherr);
 497}
 498#endif
 499
 500        if (cmd->pid < 0) {
 501                if (need_in)
 502                        close_pair(fdin);
 503                else if (cmd->in)
 504                        close(cmd->in);
 505                if (need_out)
 506                        close_pair(fdout);
 507                else if (cmd->out)
 508                        close(cmd->out);
 509                if (need_err)
 510                        close_pair(fderr);
 511                else if (cmd->err)
 512                        close(cmd->err);
 513                child_process_clear(cmd);
 514                errno = failed_errno;
 515                return -1;
 516        }
 517
 518        if (need_in)
 519                close(fdin[0]);
 520        else if (cmd->in)
 521                close(cmd->in);
 522
 523        if (need_out)
 524                close(fdout[1]);
 525        else if (cmd->out)
 526                close(cmd->out);
 527
 528        if (need_err)
 529                close(fderr[1]);
 530        else if (cmd->err)
 531                close(cmd->err);
 532
 533        return 0;
 534}
 535
 536int finish_command(struct child_process *cmd)
 537{
 538        int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 539        child_process_clear(cmd);
 540        return ret;
 541}
 542
 543int finish_command_in_signal(struct child_process *cmd)
 544{
 545        return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 546}
 547
 548
 549int run_command(struct child_process *cmd)
 550{
 551        int code;
 552
 553        if (cmd->out < 0 || cmd->err < 0)
 554                die("BUG: run_command with a pipe can cause deadlock");
 555
 556        code = start_command(cmd);
 557        if (code)
 558                return code;
 559        return finish_command(cmd);
 560}
 561
 562int run_command_v_opt(const char **argv, int opt)
 563{
 564        return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 565}
 566
 567int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 568{
 569        struct child_process cmd = CHILD_PROCESS_INIT;
 570        cmd.argv = argv;
 571        cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 572        cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 573        cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 574        cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 575        cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 576        cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 577        cmd.dir = dir;
 578        cmd.env = env;
 579        return run_command(&cmd);
 580}
 581
 582#ifndef NO_PTHREADS
 583static pthread_t main_thread;
 584static int main_thread_set;
 585static pthread_key_t async_key;
 586static pthread_key_t async_die_counter;
 587
 588static void *run_thread(void *data)
 589{
 590        struct async *async = data;
 591        intptr_t ret;
 592
 593        pthread_setspecific(async_key, async);
 594        ret = async->proc(async->proc_in, async->proc_out, async->data);
 595        return (void *)ret;
 596}
 597
 598static NORETURN void die_async(const char *err, va_list params)
 599{
 600        vreportf("fatal: ", err, params);
 601
 602        if (in_async()) {
 603                struct async *async = pthread_getspecific(async_key);
 604                if (async->proc_in >= 0)
 605                        close(async->proc_in);
 606                if (async->proc_out >= 0)
 607                        close(async->proc_out);
 608                pthread_exit((void *)128);
 609        }
 610
 611        exit(128);
 612}
 613
 614static int async_die_is_recursing(void)
 615{
 616        void *ret = pthread_getspecific(async_die_counter);
 617        pthread_setspecific(async_die_counter, (void *)1);
 618        return ret != NULL;
 619}
 620
 621int in_async(void)
 622{
 623        if (!main_thread_set)
 624                return 0; /* no asyncs started yet */
 625        return !pthread_equal(main_thread, pthread_self());
 626}
 627
 628void NORETURN async_exit(int code)
 629{
 630        pthread_exit((void *)(intptr_t)code);
 631}
 632
 633#else
 634
 635static struct {
 636        void (**handlers)(void);
 637        size_t nr;
 638        size_t alloc;
 639} git_atexit_hdlrs;
 640
 641static int git_atexit_installed;
 642
 643static void git_atexit_dispatch(void)
 644{
 645        size_t i;
 646
 647        for (i=git_atexit_hdlrs.nr ; i ; i--)
 648                git_atexit_hdlrs.handlers[i-1]();
 649}
 650
 651static void git_atexit_clear(void)
 652{
 653        free(git_atexit_hdlrs.handlers);
 654        memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 655        git_atexit_installed = 0;
 656}
 657
 658#undef atexit
 659int git_atexit(void (*handler)(void))
 660{
 661        ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 662        git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 663        if (!git_atexit_installed) {
 664                if (atexit(&git_atexit_dispatch))
 665                        return -1;
 666                git_atexit_installed = 1;
 667        }
 668        return 0;
 669}
 670#define atexit git_atexit
 671
 672static int process_is_async;
 673int in_async(void)
 674{
 675        return process_is_async;
 676}
 677
 678void NORETURN async_exit(int code)
 679{
 680        exit(code);
 681}
 682
 683#endif
 684
 685int start_async(struct async *async)
 686{
 687        int need_in, need_out;
 688        int fdin[2], fdout[2];
 689        int proc_in, proc_out;
 690
 691        need_in = async->in < 0;
 692        if (need_in) {
 693                if (pipe(fdin) < 0) {
 694                        if (async->out > 0)
 695                                close(async->out);
 696                        return error("cannot create pipe: %s", strerror(errno));
 697                }
 698                async->in = fdin[1];
 699        }
 700
 701        need_out = async->out < 0;
 702        if (need_out) {
 703                if (pipe(fdout) < 0) {
 704                        if (need_in)
 705                                close_pair(fdin);
 706                        else if (async->in)
 707                                close(async->in);
 708                        return error("cannot create pipe: %s", strerror(errno));
 709                }
 710                async->out = fdout[0];
 711        }
 712
 713        if (need_in)
 714                proc_in = fdin[0];
 715        else if (async->in)
 716                proc_in = async->in;
 717        else
 718                proc_in = -1;
 719
 720        if (need_out)
 721                proc_out = fdout[1];
 722        else if (async->out)
 723                proc_out = async->out;
 724        else
 725                proc_out = -1;
 726
 727#ifdef NO_PTHREADS
 728        /* Flush stdio before fork() to avoid cloning buffers */
 729        fflush(NULL);
 730
 731        async->pid = fork();
 732        if (async->pid < 0) {
 733                error("fork (async) failed: %s", strerror(errno));
 734                goto error;
 735        }
 736        if (!async->pid) {
 737                if (need_in)
 738                        close(fdin[1]);
 739                if (need_out)
 740                        close(fdout[0]);
 741                git_atexit_clear();
 742                process_is_async = 1;
 743                exit(!!async->proc(proc_in, proc_out, async->data));
 744        }
 745
 746        mark_child_for_cleanup(async->pid);
 747
 748        if (need_in)
 749                close(fdin[0]);
 750        else if (async->in)
 751                close(async->in);
 752
 753        if (need_out)
 754                close(fdout[1]);
 755        else if (async->out)
 756                close(async->out);
 757#else
 758        if (!main_thread_set) {
 759                /*
 760                 * We assume that the first time that start_async is called
 761                 * it is from the main thread.
 762                 */
 763                main_thread_set = 1;
 764                main_thread = pthread_self();
 765                pthread_key_create(&async_key, NULL);
 766                pthread_key_create(&async_die_counter, NULL);
 767                set_die_routine(die_async);
 768                set_die_is_recursing_routine(async_die_is_recursing);
 769        }
 770
 771        if (proc_in >= 0)
 772                set_cloexec(proc_in);
 773        if (proc_out >= 0)
 774                set_cloexec(proc_out);
 775        async->proc_in = proc_in;
 776        async->proc_out = proc_out;
 777        {
 778                int err = pthread_create(&async->tid, NULL, run_thread, async);
 779                if (err) {
 780                        error("cannot create thread: %s", strerror(err));
 781                        goto error;
 782                }
 783        }
 784#endif
 785        return 0;
 786
 787error:
 788        if (need_in)
 789                close_pair(fdin);
 790        else if (async->in)
 791                close(async->in);
 792
 793        if (need_out)
 794                close_pair(fdout);
 795        else if (async->out)
 796                close(async->out);
 797        return -1;
 798}
 799
 800int finish_async(struct async *async)
 801{
 802#ifdef NO_PTHREADS
 803        return wait_or_whine(async->pid, "child process", 0);
 804#else
 805        void *ret = (void *)(intptr_t)(-1);
 806
 807        if (pthread_join(async->tid, &ret))
 808                error("pthread_join failed");
 809        return (int)(intptr_t)ret;
 810#endif
 811}
 812
 813const char *find_hook(const char *name)
 814{
 815        static struct strbuf path = STRBUF_INIT;
 816
 817        strbuf_reset(&path);
 818        strbuf_git_path(&path, "hooks/%s", name);
 819        if (access(path.buf, X_OK) < 0)
 820                return NULL;
 821        return path.buf;
 822}
 823
 824int run_hook_ve(const char *const *env, const char *name, va_list args)
 825{
 826        struct child_process hook = CHILD_PROCESS_INIT;
 827        const char *p;
 828
 829        p = find_hook(name);
 830        if (!p)
 831                return 0;
 832
 833        argv_array_push(&hook.args, p);
 834        while ((p = va_arg(args, const char *)))
 835                argv_array_push(&hook.args, p);
 836        hook.env = env;
 837        hook.no_stdin = 1;
 838        hook.stdout_to_stderr = 1;
 839
 840        return run_command(&hook);
 841}
 842
 843int run_hook_le(const char *const *env, const char *name, ...)
 844{
 845        va_list args;
 846        int ret;
 847
 848        va_start(args, name);
 849        ret = run_hook_ve(env, name, args);
 850        va_end(args);
 851
 852        return ret;
 853}
 854
 855int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
 856{
 857        cmd->out = -1;
 858        if (start_command(cmd) < 0)
 859                return -1;
 860
 861        if (strbuf_read(buf, cmd->out, hint) < 0) {
 862                close(cmd->out);
 863                finish_command(cmd); /* throw away exit code */
 864                return -1;
 865        }
 866
 867        close(cmd->out);
 868        return finish_command(cmd);
 869}
 870
 871enum child_state {
 872        GIT_CP_FREE,
 873        GIT_CP_WORKING,
 874        GIT_CP_WAIT_CLEANUP,
 875};
 876
 877struct parallel_processes {
 878        void *data;
 879
 880        int max_processes;
 881        int nr_processes;
 882
 883        get_next_task_fn get_next_task;
 884        start_failure_fn start_failure;
 885        task_finished_fn task_finished;
 886
 887        struct {
 888                enum child_state state;
 889                struct child_process process;
 890                struct strbuf err;
 891                void *data;
 892        } *children;
 893        /*
 894         * The struct pollfd is logically part of *children,
 895         * but the system call expects it as its own array.
 896         */
 897        struct pollfd *pfd;
 898
 899        unsigned shutdown : 1;
 900
 901        int output_owner;
 902        struct strbuf buffered_output; /* of finished children */
 903};
 904
 905static int default_start_failure(struct strbuf *err,
 906                                 void *pp_cb,
 907                                 void *pp_task_cb)
 908{
 909        return 0;
 910}
 911
 912static int default_task_finished(int result,
 913                                 struct strbuf *err,
 914                                 void *pp_cb,
 915                                 void *pp_task_cb)
 916{
 917        return 0;
 918}
 919
 920static void kill_children(struct parallel_processes *pp, int signo)
 921{
 922        int i, n = pp->max_processes;
 923
 924        for (i = 0; i < n; i++)
 925                if (pp->children[i].state == GIT_CP_WORKING)
 926                        kill(pp->children[i].process.pid, signo);
 927}
 928
 929static struct parallel_processes *pp_for_signal;
 930
 931static void handle_children_on_signal(int signo)
 932{
 933        kill_children(pp_for_signal, signo);
 934        sigchain_pop(signo);
 935        raise(signo);
 936}
 937
 938static void pp_init(struct parallel_processes *pp,
 939                    int n,
 940                    get_next_task_fn get_next_task,
 941                    start_failure_fn start_failure,
 942                    task_finished_fn task_finished,
 943                    void *data)
 944{
 945        int i;
 946
 947        if (n < 1)
 948                n = online_cpus();
 949
 950        pp->max_processes = n;
 951
 952        trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
 953
 954        pp->data = data;
 955        if (!get_next_task)
 956                die("BUG: you need to specify a get_next_task function");
 957        pp->get_next_task = get_next_task;
 958
 959        pp->start_failure = start_failure ? start_failure : default_start_failure;
 960        pp->task_finished = task_finished ? task_finished : default_task_finished;
 961
 962        pp->nr_processes = 0;
 963        pp->output_owner = 0;
 964        pp->shutdown = 0;
 965        pp->children = xcalloc(n, sizeof(*pp->children));
 966        pp->pfd = xcalloc(n, sizeof(*pp->pfd));
 967        strbuf_init(&pp->buffered_output, 0);
 968
 969        for (i = 0; i < n; i++) {
 970                strbuf_init(&pp->children[i].err, 0);
 971                child_process_init(&pp->children[i].process);
 972                pp->pfd[i].events = POLLIN | POLLHUP;
 973                pp->pfd[i].fd = -1;
 974        }
 975
 976        pp_for_signal = pp;
 977        sigchain_push_common(handle_children_on_signal);
 978}
 979
 980static void pp_cleanup(struct parallel_processes *pp)
 981{
 982        int i;
 983
 984        trace_printf("run_processes_parallel: done");
 985        for (i = 0; i < pp->max_processes; i++) {
 986                strbuf_release(&pp->children[i].err);
 987                child_process_clear(&pp->children[i].process);
 988        }
 989
 990        free(pp->children);
 991        free(pp->pfd);
 992
 993        /*
 994         * When get_next_task added messages to the buffer in its last
 995         * iteration, the buffered output is non empty.
 996         */
 997        fputs(pp->buffered_output.buf, stderr);
 998        strbuf_release(&pp->buffered_output);
 999
1000        sigchain_pop_common();
1001}
1002
1003/* returns
1004 *  0 if a new task was started.
1005 *  1 if no new jobs was started (get_next_task ran out of work, non critical
1006 *    problem with starting a new command)
1007 * <0 no new job was started, user wishes to shutdown early. Use negative code
1008 *    to signal the children.
1009 */
1010static int pp_start_one(struct parallel_processes *pp)
1011{
1012        int i, code;
1013
1014        for (i = 0; i < pp->max_processes; i++)
1015                if (pp->children[i].state == GIT_CP_FREE)
1016                        break;
1017        if (i == pp->max_processes)
1018                die("BUG: bookkeeping is hard");
1019
1020        code = pp->get_next_task(&pp->children[i].process,
1021                                 &pp->children[i].err,
1022                                 pp->data,
1023                                 &pp->children[i].data);
1024        if (!code) {
1025                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1026                strbuf_reset(&pp->children[i].err);
1027                return 1;
1028        }
1029        pp->children[i].process.err = -1;
1030        pp->children[i].process.stdout_to_stderr = 1;
1031        pp->children[i].process.no_stdin = 1;
1032
1033        if (start_command(&pp->children[i].process)) {
1034                code = pp->start_failure(&pp->children[i].err,
1035                                         pp->data,
1036                                         &pp->children[i].data);
1037                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1038                strbuf_reset(&pp->children[i].err);
1039                if (code)
1040                        pp->shutdown = 1;
1041                return code;
1042        }
1043
1044        pp->nr_processes++;
1045        pp->children[i].state = GIT_CP_WORKING;
1046        pp->pfd[i].fd = pp->children[i].process.err;
1047        return 0;
1048}
1049
1050static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1051{
1052        int i;
1053
1054        while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1055                if (errno == EINTR)
1056                        continue;
1057                pp_cleanup(pp);
1058                die_errno("poll");
1059        }
1060
1061        /* Buffer output from all pipes. */
1062        for (i = 0; i < pp->max_processes; i++) {
1063                if (pp->children[i].state == GIT_CP_WORKING &&
1064                    pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1065                        int n = strbuf_read_once(&pp->children[i].err,
1066                                                 pp->children[i].process.err, 0);
1067                        if (n == 0) {
1068                                close(pp->children[i].process.err);
1069                                pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1070                        } else if (n < 0)
1071                                if (errno != EAGAIN)
1072                                        die_errno("read");
1073                }
1074        }
1075}
1076
1077static void pp_output(struct parallel_processes *pp)
1078{
1079        int i = pp->output_owner;
1080        if (pp->children[i].state == GIT_CP_WORKING &&
1081            pp->children[i].err.len) {
1082                fputs(pp->children[i].err.buf, stderr);
1083                strbuf_reset(&pp->children[i].err);
1084        }
1085}
1086
1087static int pp_collect_finished(struct parallel_processes *pp)
1088{
1089        int i, code;
1090        int n = pp->max_processes;
1091        int result = 0;
1092
1093        while (pp->nr_processes > 0) {
1094                for (i = 0; i < pp->max_processes; i++)
1095                        if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1096                                break;
1097                if (i == pp->max_processes)
1098                        break;
1099
1100                code = finish_command(&pp->children[i].process);
1101
1102                code = pp->task_finished(code,
1103                                         &pp->children[i].err, pp->data,
1104                                         &pp->children[i].data);
1105
1106                if (code)
1107                        result = code;
1108                if (code < 0)
1109                        break;
1110
1111                pp->nr_processes--;
1112                pp->children[i].state = GIT_CP_FREE;
1113                pp->pfd[i].fd = -1;
1114                child_process_init(&pp->children[i].process);
1115
1116                if (i != pp->output_owner) {
1117                        strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1118                        strbuf_reset(&pp->children[i].err);
1119                } else {
1120                        fputs(pp->children[i].err.buf, stderr);
1121                        strbuf_reset(&pp->children[i].err);
1122
1123                        /* Output all other finished child processes */
1124                        fputs(pp->buffered_output.buf, stderr);
1125                        strbuf_reset(&pp->buffered_output);
1126
1127                        /*
1128                         * Pick next process to output live.
1129                         * NEEDSWORK:
1130                         * For now we pick it randomly by doing a round
1131                         * robin. Later we may want to pick the one with
1132                         * the most output or the longest or shortest
1133                         * running process time.
1134                         */
1135                        for (i = 0; i < n; i++)
1136                                if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1137                                        break;
1138                        pp->output_owner = (pp->output_owner + i) % n;
1139                }
1140        }
1141        return result;
1142}
1143
1144int run_processes_parallel(int n,
1145                           get_next_task_fn get_next_task,
1146                           start_failure_fn start_failure,
1147                           task_finished_fn task_finished,
1148                           void *pp_cb)
1149{
1150        int i, code;
1151        int output_timeout = 100;
1152        int spawn_cap = 4;
1153        struct parallel_processes pp;
1154
1155        pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1156        while (1) {
1157                for (i = 0;
1158                    i < spawn_cap && !pp.shutdown &&
1159                    pp.nr_processes < pp.max_processes;
1160                    i++) {
1161                        code = pp_start_one(&pp);
1162                        if (!code)
1163                                continue;
1164                        if (code < 0) {
1165                                pp.shutdown = 1;
1166                                kill_children(&pp, -code);
1167                        }
1168                        break;
1169                }
1170                if (!pp.nr_processes)
1171                        break;
1172                pp_buffer_stderr(&pp, output_timeout);
1173                pp_output(&pp);
1174                code = pp_collect_finished(&pp);
1175                if (code) {
1176                        pp.shutdown = 1;
1177                        if (code < 0)
1178                                kill_children(&pp, -code);
1179                }
1180        }
1181
1182        pp_cleanup(&pp);
1183        return 0;
1184}