Andrew's git / gitweb.git / run-command.c
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run-command.con commit Eleventh batch for 2.9 (5fe494c)
   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        if (async->isolate_sigpipe) {
 594                sigset_t mask;
 595                sigemptyset(&mask);
 596                sigaddset(&mask, SIGPIPE);
 597                if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
 598                        ret = error("unable to block SIGPIPE in async thread");
 599                        return (void *)ret;
 600                }
 601        }
 602
 603        pthread_setspecific(async_key, async);
 604        ret = async->proc(async->proc_in, async->proc_out, async->data);
 605        return (void *)ret;
 606}
 607
 608static NORETURN void die_async(const char *err, va_list params)
 609{
 610        vreportf("fatal: ", err, params);
 611
 612        if (in_async()) {
 613                struct async *async = pthread_getspecific(async_key);
 614                if (async->proc_in >= 0)
 615                        close(async->proc_in);
 616                if (async->proc_out >= 0)
 617                        close(async->proc_out);
 618                pthread_exit((void *)128);
 619        }
 620
 621        exit(128);
 622}
 623
 624static int async_die_is_recursing(void)
 625{
 626        void *ret = pthread_getspecific(async_die_counter);
 627        pthread_setspecific(async_die_counter, (void *)1);
 628        return ret != NULL;
 629}
 630
 631int in_async(void)
 632{
 633        if (!main_thread_set)
 634                return 0; /* no asyncs started yet */
 635        return !pthread_equal(main_thread, pthread_self());
 636}
 637
 638void NORETURN async_exit(int code)
 639{
 640        pthread_exit((void *)(intptr_t)code);
 641}
 642
 643#else
 644
 645static struct {
 646        void (**handlers)(void);
 647        size_t nr;
 648        size_t alloc;
 649} git_atexit_hdlrs;
 650
 651static int git_atexit_installed;
 652
 653static void git_atexit_dispatch(void)
 654{
 655        size_t i;
 656
 657        for (i=git_atexit_hdlrs.nr ; i ; i--)
 658                git_atexit_hdlrs.handlers[i-1]();
 659}
 660
 661static void git_atexit_clear(void)
 662{
 663        free(git_atexit_hdlrs.handlers);
 664        memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
 665        git_atexit_installed = 0;
 666}
 667
 668#undef atexit
 669int git_atexit(void (*handler)(void))
 670{
 671        ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
 672        git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
 673        if (!git_atexit_installed) {
 674                if (atexit(&git_atexit_dispatch))
 675                        return -1;
 676                git_atexit_installed = 1;
 677        }
 678        return 0;
 679}
 680#define atexit git_atexit
 681
 682static int process_is_async;
 683int in_async(void)
 684{
 685        return process_is_async;
 686}
 687
 688void NORETURN async_exit(int code)
 689{
 690        exit(code);
 691}
 692
 693#endif
 694
 695int start_async(struct async *async)
 696{
 697        int need_in, need_out;
 698        int fdin[2], fdout[2];
 699        int proc_in, proc_out;
 700
 701        need_in = async->in < 0;
 702        if (need_in) {
 703                if (pipe(fdin) < 0) {
 704                        if (async->out > 0)
 705                                close(async->out);
 706                        return error("cannot create pipe: %s", strerror(errno));
 707                }
 708                async->in = fdin[1];
 709        }
 710
 711        need_out = async->out < 0;
 712        if (need_out) {
 713                if (pipe(fdout) < 0) {
 714                        if (need_in)
 715                                close_pair(fdin);
 716                        else if (async->in)
 717                                close(async->in);
 718                        return error("cannot create pipe: %s", strerror(errno));
 719                }
 720                async->out = fdout[0];
 721        }
 722
 723        if (need_in)
 724                proc_in = fdin[0];
 725        else if (async->in)
 726                proc_in = async->in;
 727        else
 728                proc_in = -1;
 729
 730        if (need_out)
 731                proc_out = fdout[1];
 732        else if (async->out)
 733                proc_out = async->out;
 734        else
 735                proc_out = -1;
 736
 737#ifdef NO_PTHREADS
 738        /* Flush stdio before fork() to avoid cloning buffers */
 739        fflush(NULL);
 740
 741        async->pid = fork();
 742        if (async->pid < 0) {
 743                error("fork (async) failed: %s", strerror(errno));
 744                goto error;
 745        }
 746        if (!async->pid) {
 747                if (need_in)
 748                        close(fdin[1]);
 749                if (need_out)
 750                        close(fdout[0]);
 751                git_atexit_clear();
 752                process_is_async = 1;
 753                exit(!!async->proc(proc_in, proc_out, async->data));
 754        }
 755
 756        mark_child_for_cleanup(async->pid);
 757
 758        if (need_in)
 759                close(fdin[0]);
 760        else if (async->in)
 761                close(async->in);
 762
 763        if (need_out)
 764                close(fdout[1]);
 765        else if (async->out)
 766                close(async->out);
 767#else
 768        if (!main_thread_set) {
 769                /*
 770                 * We assume that the first time that start_async is called
 771                 * it is from the main thread.
 772                 */
 773                main_thread_set = 1;
 774                main_thread = pthread_self();
 775                pthread_key_create(&async_key, NULL);
 776                pthread_key_create(&async_die_counter, NULL);
 777                set_die_routine(die_async);
 778                set_die_is_recursing_routine(async_die_is_recursing);
 779        }
 780
 781        if (proc_in >= 0)
 782                set_cloexec(proc_in);
 783        if (proc_out >= 0)
 784                set_cloexec(proc_out);
 785        async->proc_in = proc_in;
 786        async->proc_out = proc_out;
 787        {
 788                int err = pthread_create(&async->tid, NULL, run_thread, async);
 789                if (err) {
 790                        error("cannot create thread: %s", strerror(err));
 791                        goto error;
 792                }
 793        }
 794#endif
 795        return 0;
 796
 797error:
 798        if (need_in)
 799                close_pair(fdin);
 800        else if (async->in)
 801                close(async->in);
 802
 803        if (need_out)
 804                close_pair(fdout);
 805        else if (async->out)
 806                close(async->out);
 807        return -1;
 808}
 809
 810int finish_async(struct async *async)
 811{
 812#ifdef NO_PTHREADS
 813        return wait_or_whine(async->pid, "child process", 0);
 814#else
 815        void *ret = (void *)(intptr_t)(-1);
 816
 817        if (pthread_join(async->tid, &ret))
 818                error("pthread_join failed");
 819        return (int)(intptr_t)ret;
 820#endif
 821}
 822
 823const char *find_hook(const char *name)
 824{
 825        static struct strbuf path = STRBUF_INIT;
 826
 827        strbuf_reset(&path);
 828        strbuf_git_path(&path, "hooks/%s", name);
 829        if (access(path.buf, X_OK) < 0)
 830                return NULL;
 831        return path.buf;
 832}
 833
 834int run_hook_ve(const char *const *env, const char *name, va_list args)
 835{
 836        struct child_process hook = CHILD_PROCESS_INIT;
 837        const char *p;
 838
 839        p = find_hook(name);
 840        if (!p)
 841                return 0;
 842
 843        argv_array_push(&hook.args, p);
 844        while ((p = va_arg(args, const char *)))
 845                argv_array_push(&hook.args, p);
 846        hook.env = env;
 847        hook.no_stdin = 1;
 848        hook.stdout_to_stderr = 1;
 849
 850        return run_command(&hook);
 851}
 852
 853int run_hook_le(const char *const *env, const char *name, ...)
 854{
 855        va_list args;
 856        int ret;
 857
 858        va_start(args, name);
 859        ret = run_hook_ve(env, name, args);
 860        va_end(args);
 861
 862        return ret;
 863}
 864
 865int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
 866{
 867        cmd->out = -1;
 868        if (start_command(cmd) < 0)
 869                return -1;
 870
 871        if (strbuf_read(buf, cmd->out, hint) < 0) {
 872                close(cmd->out);
 873                finish_command(cmd); /* throw away exit code */
 874                return -1;
 875        }
 876
 877        close(cmd->out);
 878        return finish_command(cmd);
 879}
 880
 881enum child_state {
 882        GIT_CP_FREE,
 883        GIT_CP_WORKING,
 884        GIT_CP_WAIT_CLEANUP,
 885};
 886
 887struct parallel_processes {
 888        void *data;
 889
 890        int max_processes;
 891        int nr_processes;
 892
 893        get_next_task_fn get_next_task;
 894        start_failure_fn start_failure;
 895        task_finished_fn task_finished;
 896
 897        struct {
 898                enum child_state state;
 899                struct child_process process;
 900                struct strbuf err;
 901                void *data;
 902        } *children;
 903        /*
 904         * The struct pollfd is logically part of *children,
 905         * but the system call expects it as its own array.
 906         */
 907        struct pollfd *pfd;
 908
 909        unsigned shutdown : 1;
 910
 911        int output_owner;
 912        struct strbuf buffered_output; /* of finished children */
 913};
 914
 915static int default_start_failure(struct strbuf *out,
 916                                 void *pp_cb,
 917                                 void *pp_task_cb)
 918{
 919        return 0;
 920}
 921
 922static int default_task_finished(int result,
 923                                 struct strbuf *out,
 924                                 void *pp_cb,
 925                                 void *pp_task_cb)
 926{
 927        return 0;
 928}
 929
 930static void kill_children(struct parallel_processes *pp, int signo)
 931{
 932        int i, n = pp->max_processes;
 933
 934        for (i = 0; i < n; i++)
 935                if (pp->children[i].state == GIT_CP_WORKING)
 936                        kill(pp->children[i].process.pid, signo);
 937}
 938
 939static struct parallel_processes *pp_for_signal;
 940
 941static void handle_children_on_signal(int signo)
 942{
 943        kill_children(pp_for_signal, signo);
 944        sigchain_pop(signo);
 945        raise(signo);
 946}
 947
 948static void pp_init(struct parallel_processes *pp,
 949                    int n,
 950                    get_next_task_fn get_next_task,
 951                    start_failure_fn start_failure,
 952                    task_finished_fn task_finished,
 953                    void *data)
 954{
 955        int i;
 956
 957        if (n < 1)
 958                n = online_cpus();
 959
 960        pp->max_processes = n;
 961
 962        trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
 963
 964        pp->data = data;
 965        if (!get_next_task)
 966                die("BUG: you need to specify a get_next_task function");
 967        pp->get_next_task = get_next_task;
 968
 969        pp->start_failure = start_failure ? start_failure : default_start_failure;
 970        pp->task_finished = task_finished ? task_finished : default_task_finished;
 971
 972        pp->nr_processes = 0;
 973        pp->output_owner = 0;
 974        pp->shutdown = 0;
 975        pp->children = xcalloc(n, sizeof(*pp->children));
 976        pp->pfd = xcalloc(n, sizeof(*pp->pfd));
 977        strbuf_init(&pp->buffered_output, 0);
 978
 979        for (i = 0; i < n; i++) {
 980                strbuf_init(&pp->children[i].err, 0);
 981                child_process_init(&pp->children[i].process);
 982                pp->pfd[i].events = POLLIN | POLLHUP;
 983                pp->pfd[i].fd = -1;
 984        }
 985
 986        pp_for_signal = pp;
 987        sigchain_push_common(handle_children_on_signal);
 988}
 989
 990static void pp_cleanup(struct parallel_processes *pp)
 991{
 992        int i;
 993
 994        trace_printf("run_processes_parallel: done");
 995        for (i = 0; i < pp->max_processes; i++) {
 996                strbuf_release(&pp->children[i].err);
 997                child_process_clear(&pp->children[i].process);
 998        }
 999
1000        free(pp->children);
1001        free(pp->pfd);
1002
1003        /*
1004         * When get_next_task added messages to the buffer in its last
1005         * iteration, the buffered output is non empty.
1006         */
1007        strbuf_write(&pp->buffered_output, stderr);
1008        strbuf_release(&pp->buffered_output);
1009
1010        sigchain_pop_common();
1011}
1012
1013/* returns
1014 *  0 if a new task was started.
1015 *  1 if no new jobs was started (get_next_task ran out of work, non critical
1016 *    problem with starting a new command)
1017 * <0 no new job was started, user wishes to shutdown early. Use negative code
1018 *    to signal the children.
1019 */
1020static int pp_start_one(struct parallel_processes *pp)
1021{
1022        int i, code;
1023
1024        for (i = 0; i < pp->max_processes; i++)
1025                if (pp->children[i].state == GIT_CP_FREE)
1026                        break;
1027        if (i == pp->max_processes)
1028                die("BUG: bookkeeping is hard");
1029
1030        code = pp->get_next_task(&pp->children[i].process,
1031                                 &pp->children[i].err,
1032                                 pp->data,
1033                                 &pp->children[i].data);
1034        if (!code) {
1035                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1036                strbuf_reset(&pp->children[i].err);
1037                return 1;
1038        }
1039        pp->children[i].process.err = -1;
1040        pp->children[i].process.stdout_to_stderr = 1;
1041        pp->children[i].process.no_stdin = 1;
1042
1043        if (start_command(&pp->children[i].process)) {
1044                code = pp->start_failure(&pp->children[i].err,
1045                                         pp->data,
1046                                         &pp->children[i].data);
1047                strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1048                strbuf_reset(&pp->children[i].err);
1049                if (code)
1050                        pp->shutdown = 1;
1051                return code;
1052        }
1053
1054        pp->nr_processes++;
1055        pp->children[i].state = GIT_CP_WORKING;
1056        pp->pfd[i].fd = pp->children[i].process.err;
1057        return 0;
1058}
1059
1060static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1061{
1062        int i;
1063
1064        while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1065                if (errno == EINTR)
1066                        continue;
1067                pp_cleanup(pp);
1068                die_errno("poll");
1069        }
1070
1071        /* Buffer output from all pipes. */
1072        for (i = 0; i < pp->max_processes; i++) {
1073                if (pp->children[i].state == GIT_CP_WORKING &&
1074                    pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1075                        int n = strbuf_read_once(&pp->children[i].err,
1076                                                 pp->children[i].process.err, 0);
1077                        if (n == 0) {
1078                                close(pp->children[i].process.err);
1079                                pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1080                        } else if (n < 0)
1081                                if (errno != EAGAIN)
1082                                        die_errno("read");
1083                }
1084        }
1085}
1086
1087static void pp_output(struct parallel_processes *pp)
1088{
1089        int i = pp->output_owner;
1090        if (pp->children[i].state == GIT_CP_WORKING &&
1091            pp->children[i].err.len) {
1092                strbuf_write(&pp->children[i].err, stderr);
1093                strbuf_reset(&pp->children[i].err);
1094        }
1095}
1096
1097static int pp_collect_finished(struct parallel_processes *pp)
1098{
1099        int i, code;
1100        int n = pp->max_processes;
1101        int result = 0;
1102
1103        while (pp->nr_processes > 0) {
1104                for (i = 0; i < pp->max_processes; i++)
1105                        if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1106                                break;
1107                if (i == pp->max_processes)
1108                        break;
1109
1110                code = finish_command(&pp->children[i].process);
1111
1112                code = pp->task_finished(code,
1113                                         &pp->children[i].err, pp->data,
1114                                         &pp->children[i].data);
1115
1116                if (code)
1117                        result = code;
1118                if (code < 0)
1119                        break;
1120
1121                pp->nr_processes--;
1122                pp->children[i].state = GIT_CP_FREE;
1123                pp->pfd[i].fd = -1;
1124                child_process_init(&pp->children[i].process);
1125
1126                if (i != pp->output_owner) {
1127                        strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1128                        strbuf_reset(&pp->children[i].err);
1129                } else {
1130                        strbuf_write(&pp->children[i].err, stderr);
1131                        strbuf_reset(&pp->children[i].err);
1132
1133                        /* Output all other finished child processes */
1134                        strbuf_write(&pp->buffered_output, stderr);
1135                        strbuf_reset(&pp->buffered_output);
1136
1137                        /*
1138                         * Pick next process to output live.
1139                         * NEEDSWORK:
1140                         * For now we pick it randomly by doing a round
1141                         * robin. Later we may want to pick the one with
1142                         * the most output or the longest or shortest
1143                         * running process time.
1144                         */
1145                        for (i = 0; i < n; i++)
1146                                if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1147                                        break;
1148                        pp->output_owner = (pp->output_owner + i) % n;
1149                }
1150        }
1151        return result;
1152}
1153
1154int run_processes_parallel(int n,
1155                           get_next_task_fn get_next_task,
1156                           start_failure_fn start_failure,
1157                           task_finished_fn task_finished,
1158                           void *pp_cb)
1159{
1160        int i, code;
1161        int output_timeout = 100;
1162        int spawn_cap = 4;
1163        struct parallel_processes pp;
1164
1165        pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1166        while (1) {
1167                for (i = 0;
1168                    i < spawn_cap && !pp.shutdown &&
1169                    pp.nr_processes < pp.max_processes;
1170                    i++) {
1171                        code = pp_start_one(&pp);
1172                        if (!code)
1173                                continue;
1174                        if (code < 0) {
1175                                pp.shutdown = 1;
1176                                kill_children(&pp, -code);
1177                        }
1178                        break;
1179                }
1180                if (!pp.nr_processes)
1181                        break;
1182                pp_buffer_stderr(&pp, output_timeout);
1183                pp_output(&pp);
1184                code = pp_collect_finished(&pp);
1185                if (code) {
1186                        pp.shutdown = 1;
1187                        if (code < 0)
1188                                kill_children(&pp, -code);
1189                }
1190        }
1191
1192        pp_cleanup(&pp);
1193        return 0;
1194}