Andrew's git / gitweb.git / run-command.c
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run-command.con commit Merge branch 'kb/msys2-tty' (07ffe87)
   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_errno("waitpid for %s failed", argv0);
 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_errno("cannot fork() for %s", cmd->argv[0]);
 424        else if (cmd->clean_on_exit)
 425                mark_child_for_cleanup(cmd->pid);
 426
 427        /*
 428         * Wait for child's execvp. If the execvp succeeds (or if fork()
 429         * failed), EOF is seen immediately by the parent. Otherwise, the
 430         * child process sends a single byte.
 431         * Note that use of this infrastructure is completely advisory,
 432         * therefore, we keep error checks minimal.
 433         */
 434        close(notify_pipe[1]);
 435        if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 436                /*
 437                 * At this point we know that fork() succeeded, but execvp()
 438                 * failed. Errors have been reported to our stderr.
 439                 */
 440                wait_or_whine(cmd->pid, cmd->argv[0], 0);
 441                failed_errno = errno;
 442                cmd->pid = -1;
 443        }
 444        close(notify_pipe[0]);
 445}
 446#else
 447{
 448        int fhin = 0, fhout = 1, fherr = 2;
 449        const char **sargv = cmd->argv;
 450        struct argv_array nargv = ARGV_ARRAY_INIT;
 451
 452        if (cmd->no_stdin)
 453                fhin = open("/dev/null", O_RDWR);
 454        else if (need_in)
 455                fhin = dup(fdin[0]);
 456        else if (cmd->in)
 457                fhin = dup(cmd->in);
 458
 459        if (cmd->no_stderr)
 460                fherr = open("/dev/null", O_RDWR);
 461        else if (need_err)
 462                fherr = dup(fderr[1]);
 463        else if (cmd->err > 2)
 464                fherr = dup(cmd->err);
 465
 466        if (cmd->no_stdout)
 467                fhout = open("/dev/null", O_RDWR);
 468        else if (cmd->stdout_to_stderr)
 469                fhout = dup(fherr);
 470        else if (need_out)
 471                fhout = dup(fdout[1]);
 472        else if (cmd->out > 1)
 473                fhout = dup(cmd->out);
 474
 475        if (cmd->git_cmd)
 476                cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
 477        else if (cmd->use_shell)
 478                cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
 479
 480        cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
 481                        cmd->dir, fhin, fhout, fherr);
 482        failed_errno = errno;
 483        if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 484                error_errno("cannot spawn %s", cmd->argv[0]);
 485        if (cmd->clean_on_exit && cmd->pid >= 0)
 486                mark_child_for_cleanup(cmd->pid);
 487
 488        argv_array_clear(&nargv);
 489        cmd->argv = sargv;
 490        if (fhin != 0)
 491                close(fhin);
 492        if (fhout != 1)
 493                close(fhout);
 494        if (fherr != 2)
 495                close(fherr);
 496}
 497#endif
 498
 499        if (cmd->pid < 0) {
 500                if (need_in)
 501                        close_pair(fdin);
 502                else if (cmd->in)
 503                        close(cmd->in);
 504                if (need_out)
 505                        close_pair(fdout);
 506                else if (cmd->out)
 507                        close(cmd->out);
 508                if (need_err)
 509                        close_pair(fderr);
 510                else if (cmd->err)
 511                        close(cmd->err);
 512                child_process_clear(cmd);
 513                errno = failed_errno;
 514                return -1;
 515        }
 516
 517        if (need_in)
 518                close(fdin[0]);
 519        else if (cmd->in)
 520                close(cmd->in);
 521
 522        if (need_out)
 523                close(fdout[1]);
 524        else if (cmd->out)
 525                close(cmd->out);
 526
 527        if (need_err)
 528                close(fderr[1]);
 529        else if (cmd->err)
 530                close(cmd->err);
 531
 532        return 0;
 533}
 534
 535int finish_command(struct child_process *cmd)
 536{
 537        int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 538        child_process_clear(cmd);
 539        return ret;
 540}
 541
 542int finish_command_in_signal(struct child_process *cmd)
 543{
 544        return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 545}
 546
 547
 548int run_command(struct child_process *cmd)
 549{
 550        int code;
 551
 552        if (cmd->out < 0 || cmd->err < 0)
 553                die("BUG: run_command with a pipe can cause deadlock");
 554
 555        code = start_command(cmd);
 556        if (code)
 557                return code;
 558        return finish_command(cmd);
 559}
 560
 561int run_command_v_opt(const char **argv, int opt)
 562{
 563        return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 564}
 565
 566int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 567{
 568        struct child_process cmd = CHILD_PROCESS_INIT;
 569        cmd.argv = argv;
 570        cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 571        cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 572        cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 573        cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 574        cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
 575        cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 576        cmd.dir = dir;
 577        cmd.env = env;
 578        return run_command(&cmd);
 579}
 580
 581#ifndef NO_PTHREADS
 582static pthread_t main_thread;
 583static int main_thread_set;
 584static pthread_key_t async_key;
 585static pthread_key_t async_die_counter;
 586
 587static void *run_thread(void *data)
 588{
 589        struct async *async = data;
 590        intptr_t ret;
 591
 592        if (async->isolate_sigpipe) {
 593                sigset_t mask;
 594                sigemptyset(&mask);
 595                sigaddset(&mask, SIGPIPE);
 596                if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 597                        ret = error("unable to block SIGPIPE in async thread");
 598                        return (void *)ret;
 599                }
 600        }
 601
 602        pthread_setspecific(async_key, async);
 603        ret = async->proc(async->proc_in, async->proc_out, async->data);
 604        return (void *)ret;
 605}
 606
 607static NORETURN void die_async(const char *err, va_list params)
 608{
 609        vreportf("fatal: ", err, params);
 610
 611        if (in_async()) {
 612                struct async *async = pthread_getspecific(async_key);
 613                if (async->proc_in >= 0)
 614                        close(async->proc_in);
 615                if (async->proc_out >= 0)
 616                        close(async->proc_out);
 617                pthread_exit((void *)128);
 618        }
 619
 620        exit(128);
 621}
 622
 623static int async_die_is_recursing(void)
 624{
 625        void *ret = pthread_getspecific(async_die_counter);
 626        pthread_setspecific(async_die_counter, (void *)1);
 627        return ret != NULL;
 628}
 629
 630int in_async(void)
 631{
 632        if (!main_thread_set)
 633                return 0; /* no asyncs started yet */
 634        return !pthread_equal(main_thread, pthread_self());
 635}
 636
 637void NORETURN async_exit(int code)
 638{
 639        pthread_exit((void *)(intptr_t)code);
 640}
 641
 642#else
 643
 644static struct {
 645        void (**handlers)(void);
 646        size_t nr;
 647        size_t alloc;
 648} git_atexit_hdlrs;
 649
 650static int git_atexit_installed;
 651
 652static void git_atexit_dispatch(void)
 653{
 654        size_t i;
 655
 656        for (i=git_atexit_hdlrs.nr ; i ; i--)
 657                git_atexit_hdlrs.handlers[i-1]();
 658}
 659
 660static void git_atexit_clear(void)
 661{
 662        free(git_atexit_hdlrs.handlers);
 663        memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 664        git_atexit_installed = 0;
 665}
 666
 667#undef atexit
 668int git_atexit(void (*handler)(void))
 669{
 670        ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 671        git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 672        if (!git_atexit_installed) {
 673                if (atexit(&git_atexit_dispatch))
 674                        return -1;
 675                git_atexit_installed = 1;
 676        }
 677        return 0;
 678}
 679#define atexit git_atexit
 680
 681static int process_is_async;
 682int in_async(void)
 683{
 684        return process_is_async;
 685}
 686
 687void NORETURN async_exit(int code)
 688{
 689        exit(code);
 690}
 691
 692#endif
 693
 694int start_async(struct async *async)
 695{
 696        int need_in, need_out;
 697        int fdin[2], fdout[2];
 698        int proc_in, proc_out;
 699
 700        need_in = async->in < 0;
 701        if (need_in) {
 702                if (pipe(fdin) < 0) {
 703                        if (async->out > 0)
 704                                close(async->out);
 705                        return error_errno("cannot create pipe");
 706                }
 707                async->in = fdin[1];
 708        }
 709
 710        need_out = async->out < 0;
 711        if (need_out) {
 712                if (pipe(fdout) < 0) {
 713                        if (need_in)
 714                                close_pair(fdin);
 715                        else if (async->in)
 716                                close(async->in);
 717                        return error_errno("cannot create pipe");
 718                }
 719                async->out = fdout[0];
 720        }
 721
 722        if (need_in)
 723                proc_in = fdin[0];
 724        else if (async->in)
 725                proc_in = async->in;
 726        else
 727                proc_in = -1;
 728
 729        if (need_out)
 730                proc_out = fdout[1];
 731        else if (async->out)
 732                proc_out = async->out;
 733        else
 734                proc_out = -1;
 735
 736#ifdef NO_PTHREADS
 737        /* Flush stdio before fork() to avoid cloning buffers */
 738        fflush(NULL);
 739
 740        async->pid = fork();
 741        if (async->pid < 0) {
 742                error_errno("fork (async) failed");
 743                goto error;
 744        }
 745        if (!async->pid) {
 746                if (need_in)
 747                        close(fdin[1]);
 748                if (need_out)
 749                        close(fdout[0]);
 750                git_atexit_clear();
 751                process_is_async = 1;
 752                exit(!!async->proc(proc_in, proc_out, async->data));
 753        }
 754
 755        mark_child_for_cleanup(async->pid);
 756
 757        if (need_in)
 758                close(fdin[0]);
 759        else if (async->in)
 760                close(async->in);
 761
 762        if (need_out)
 763                close(fdout[1]);
 764        else if (async->out)
 765                close(async->out);
 766#else
 767        if (!main_thread_set) {
 768                /*
 769                 * We assume that the first time that start_async is called
 770                 * it is from the main thread.
 771                 */
 772                main_thread_set = 1;
 773                main_thread = pthread_self();
 774                pthread_key_create(&async_key, NULL);
 775                pthread_key_create(&async_die_counter, NULL);
 776                set_die_routine(die_async);
 777                set_die_is_recursing_routine(async_die_is_recursing);
 778        }
 779
 780        if (proc_in >= 0)
 781                set_cloexec(proc_in);
 782        if (proc_out >= 0)
 783                set_cloexec(proc_out);
 784        async->proc_in = proc_in;
 785        async->proc_out = proc_out;
 786        {
 787                int err = pthread_create(&async->tid, NULL, run_thread, async);
 788                if (err) {
 789                        error_errno("cannot create thread");
 790                        goto error;
 791                }
 792        }
 793#endif
 794        return 0;
 795
 796error:
 797        if (need_in)
 798                close_pair(fdin);
 799        else if (async->in)
 800                close(async->in);
 801
 802        if (need_out)
 803                close_pair(fdout);
 804        else if (async->out)
 805                close(async->out);
 806        return -1;
 807}
 808
 809int finish_async(struct async *async)
 810{
 811#ifdef NO_PTHREADS
 812        return wait_or_whine(async->pid, "child process", 0);
 813#else
 814        void *ret = (void *)(intptr_t)(-1);
 815
 816        if (pthread_join(async->tid, &ret))
 817                error("pthread_join failed");
 818        return (int)(intptr_t)ret;
 819#endif
 820}
 821
 822const char *find_hook(const char *name)
 823{
 824        static struct strbuf path = STRBUF_INIT;
 825
 826        strbuf_reset(&path);
 827        if (git_hooks_path)
 828                strbuf_addf(&path, "%s/%s", git_hooks_path, name);
 829        else
 830                strbuf_git_path(&path, "hooks/%s", name);
 831        if (access(path.buf, X_OK) < 0)
 832                return NULL;
 833        return path.buf;
 834}
 835
 836int run_hook_ve(const char *const *env, const char *name, va_list args)
 837{
 838        struct child_process hook = CHILD_PROCESS_INIT;
 839        const char *p;
 840
 841        p = find_hook(name);
 842        if (!p)
 843                return 0;
 844
 845        argv_array_push(&hook.args, p);
 846        while ((p = va_arg(args, const char *)))
 847                argv_array_push(&hook.args, p);
 848        hook.env = env;
 849        hook.no_stdin = 1;
 850        hook.stdout_to_stderr = 1;
 851
 852        return run_command(&hook);
 853}
 854
 855int run_hook_le(const char *const *env, const char *name, ...)
 856{
 857        va_list args;
 858        int ret;
 859
 860        va_start(args, name);
 861        ret = run_hook_ve(env, name, args);
 862        va_end(args);
 863
 864        return ret;
 865}
 866
 867int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
 868{
 869        cmd->out = -1;
 870        if (start_command(cmd) < 0)
 871                return -1;
 872
 873        if (strbuf_read(buf, cmd->out, hint) < 0) {
 874                close(cmd->out);
 875                finish_command(cmd); /* throw away exit code */
 876                return -1;
 877        }
 878
 879        close(cmd->out);
 880        return finish_command(cmd);
 881}
 882
 883enum child_state {
 884        GIT_CP_FREE,
 885        GIT_CP_WORKING,
 886        GIT_CP_WAIT_CLEANUP,
 887};
 888
 889struct parallel_processes {
 890        void *data;
 891
 892        int max_processes;
 893        int nr_processes;
 894
 895        get_next_task_fn get_next_task;
 896        start_failure_fn start_failure;
 897        task_finished_fn task_finished;
 898
 899        struct {
 900                enum child_state state;
 901                struct child_process process;
 902                struct strbuf err;
 903                void *data;
 904        } *children;
 905        /*
 906         * The struct pollfd is logically part of *children,
 907         * but the system call expects it as its own array.
 908         */
 909        struct pollfd *pfd;
 910
 911        unsigned shutdown : 1;
 912
 913        int output_owner;
 914        struct strbuf buffered_output; /* of finished children */
 915};
 916
 917static int default_start_failure(struct strbuf *out,
 918                                 void *pp_cb,
 919                                 void *pp_task_cb)
 920{
 921        return 0;
 922}
 923
 924static int default_task_finished(int result,
 925                                 struct strbuf *out,
 926                                 void *pp_cb,
 927                                 void *pp_task_cb)
 928{
 929        return 0;
 930}
 931
 932static void kill_children(struct parallel_processes *pp, int signo)
 933{
 934        int i, n = pp->max_processes;
 935
 936        for (i = 0; i < n; i++)
 937                if (pp->children[i].state == GIT_CP_WORKING)
 938                        kill(pp->children[i].process.pid, signo);
 939}
 940
 941static struct parallel_processes *pp_for_signal;
 942
 943static void handle_children_on_signal(int signo)
 944{
 945        kill_children(pp_for_signal, signo);
 946        sigchain_pop(signo);
 947        raise(signo);
 948}
 949
 950static void pp_init(struct parallel_processes *pp,
 951                    int n,
 952                    get_next_task_fn get_next_task,
 953                    start_failure_fn start_failure,
 954                    task_finished_fn task_finished,
 955                    void *data)
 956{
 957        int i;
 958
 959        if (n < 1)
 960                n = online_cpus();
 961
 962        pp->max_processes = n;
 963
 964        trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
 965
 966        pp->data = data;
 967        if (!get_next_task)
 968                die("BUG: you need to specify a get_next_task function");
 969        pp->get_next_task = get_next_task;
 970
 971        pp->start_failure = start_failure ? start_failure : default_start_failure;
 972        pp->task_finished = task_finished ? task_finished : default_task_finished;
 973
 974        pp->nr_processes = 0;
 975        pp->output_owner = 0;
 976        pp->shutdown = 0;
 977        pp->children = xcalloc(n, sizeof(*pp->children));
 978        pp->pfd = xcalloc(n, sizeof(*pp->pfd));
 979        strbuf_init(&pp->buffered_output, 0);
 980
 981        for (i = 0; i < n; i++) {
 982                strbuf_init(&pp->children[i].err, 0);
 983                child_process_init(&pp->children[i].process);
 984                pp->pfd[i].events = POLLIN | POLLHUP;
 985                pp->pfd[i].fd = -1;
 986        }
 987
 988        pp_for_signal = pp;
 989        sigchain_push_common(handle_children_on_signal);
 990}
 991
 992static void pp_cleanup(struct parallel_processes *pp)
 993{
 994        int i;
 995
 996        trace_printf("run_processes_parallel: done");
 997        for (i = 0; i < pp->max_processes; i++) {
 998                strbuf_release(&pp->children[i].err);
 999                child_process_clear(&pp->children[i].process);
1000        }
1001
1002        free(pp->children);
1003        free(pp->pfd);
1004
1005        /*
1006         * When get_next_task added messages to the buffer in its last
1007         * iteration, the buffered output is non empty.
1008         */
1009        strbuf_write(&pp->buffered_output, stderr);
1010        strbuf_release(&pp->buffered_output);
1011
1012        sigchain_pop_common();
1013}
1014
1015/* returns
1016 *  0 if a new task was started.
1017 *  1 if no new jobs was started (get_next_task ran out of work, non critical
1018 *    problem with starting a new command)
1019 * <0 no new job was started, user wishes to shutdown early. Use negative code
1020 *    to signal the children.
1021 */
1022static int pp_start_one(struct parallel_processes *pp)
1023{
1024        int i, code;
1025
1026        for (i = 0; i < pp->max_processes; i++)
1027                if (pp->children[i].state == GIT_CP_FREE)
1028                        break;
1029        if (i == pp->max_processes)
1030                die("BUG: bookkeeping is hard");
1031
1032        code = pp->get_next_task(&pp->children[i].process,
1033                                 &pp->children[i].err,
1034                                 pp->data,
1035                                 &pp->children[i].data);
1036        if (!code) {
1037                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1038                strbuf_reset(&pp->children[i].err);
1039                return 1;
1040        }
1041        pp->children[i].process.err = -1;
1042        pp->children[i].process.stdout_to_stderr = 1;
1043        pp->children[i].process.no_stdin = 1;
1044
1045        if (start_command(&pp->children[i].process)) {
1046                code = pp->start_failure(&pp->children[i].err,
1047                                         pp->data,
1048                                         &pp->children[i].data);
1049                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1050                strbuf_reset(&pp->children[i].err);
1051                if (code)
1052                        pp->shutdown = 1;
1053                return code;
1054        }
1055
1056        pp->nr_processes++;
1057        pp->children[i].state = GIT_CP_WORKING;
1058        pp->pfd[i].fd = pp->children[i].process.err;
1059        return 0;
1060}
1061
1062static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1063{
1064        int i;
1065
1066        while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1067                if (errno == EINTR)
1068                        continue;
1069                pp_cleanup(pp);
1070                die_errno("poll");
1071        }
1072
1073        /* Buffer output from all pipes. */
1074        for (i = 0; i < pp->max_processes; i++) {
1075                if (pp->children[i].state == GIT_CP_WORKING &&
1076                    pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1077                        int n = strbuf_read_once(&pp->children[i].err,
1078                                                 pp->children[i].process.err, 0);
1079                        if (n == 0) {
1080                                close(pp->children[i].process.err);
1081                                pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1082                        } else if (n < 0)
1083                                if (errno != EAGAIN)
1084                                        die_errno("read");
1085                }
1086        }
1087}
1088
1089static void pp_output(struct parallel_processes *pp)
1090{
1091        int i = pp->output_owner;
1092        if (pp->children[i].state == GIT_CP_WORKING &&
1093            pp->children[i].err.len) {
1094                strbuf_write(&pp->children[i].err, stderr);
1095                strbuf_reset(&pp->children[i].err);
1096        }
1097}
1098
1099static int pp_collect_finished(struct parallel_processes *pp)
1100{
1101        int i, code;
1102        int n = pp->max_processes;
1103        int result = 0;
1104
1105        while (pp->nr_processes > 0) {
1106                for (i = 0; i < pp->max_processes; i++)
1107                        if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1108                                break;
1109                if (i == pp->max_processes)
1110                        break;
1111
1112                code = finish_command(&pp->children[i].process);
1113
1114                code = pp->task_finished(code,
1115                                         &pp->children[i].err, pp->data,
1116                                         &pp->children[i].data);
1117
1118                if (code)
1119                        result = code;
1120                if (code < 0)
1121                        break;
1122
1123                pp->nr_processes--;
1124                pp->children[i].state = GIT_CP_FREE;
1125                pp->pfd[i].fd = -1;
1126                child_process_init(&pp->children[i].process);
1127
1128                if (i != pp->output_owner) {
1129                        strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1130                        strbuf_reset(&pp->children[i].err);
1131                } else {
1132                        strbuf_write(&pp->children[i].err, stderr);
1133                        strbuf_reset(&pp->children[i].err);
1134
1135                        /* Output all other finished child processes */
1136                        strbuf_write(&pp->buffered_output, stderr);
1137                        strbuf_reset(&pp->buffered_output);
1138
1139                        /*
1140                         * Pick next process to output live.
1141                         * NEEDSWORK:
1142                         * For now we pick it randomly by doing a round
1143                         * robin. Later we may want to pick the one with
1144                         * the most output or the longest or shortest
1145                         * running process time.
1146                         */
1147                        for (i = 0; i < n; i++)
1148                                if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1149                                        break;
1150                        pp->output_owner = (pp->output_owner + i) % n;
1151                }
1152        }
1153        return result;
1154}
1155
1156int run_processes_parallel(int n,
1157                           get_next_task_fn get_next_task,
1158                           start_failure_fn start_failure,
1159                           task_finished_fn task_finished,
1160                           void *pp_cb)
1161{
1162        int i, code;
1163        int output_timeout = 100;
1164        int spawn_cap = 4;
1165        struct parallel_processes pp;
1166
1167        pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1168        while (1) {
1169                for (i = 0;
1170                    i < spawn_cap && !pp.shutdown &&
1171                    pp.nr_processes < pp.max_processes;
1172                    i++) {
1173                        code = pp_start_one(&pp);
1174                        if (!code)
1175                                continue;
1176                        if (code < 0) {
1177                                pp.shutdown = 1;
1178                                kill_children(&pp, -code);
1179                        }
1180                        break;
1181                }
1182                if (!pp.nr_processes)
1183                        break;
1184                pp_buffer_stderr(&pp, output_timeout);
1185                pp_output(&pp);
1186                code = pp_collect_finished(&pp);
1187                if (code) {
1188                        pp.shutdown = 1;
1189                        if (code < 0)
1190                                kill_children(&pp, -code);
1191                }
1192        }
1193
1194        pp_cleanup(&pp);
1195        return 0;
1196}