Andrew's git / gitweb.git / fetch-pack.c
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fetch-pack.con commit Merge branch 'maint' of git://repo.or.cz/git-gui into maint (7468c29)
   1#include "cache.h"
   2#include "refs.h"
   3#include "pkt-line.h"
   4#include "commit.h"
   5#include "tag.h"
   6#include "exec_cmd.h"
   7#include "pack.h"
   8#include "sideband.h"
   9
  10static int keep_pack;
  11static int transfer_unpack_limit = -1;
  12static int fetch_unpack_limit = -1;
  13static int unpack_limit = 100;
  14static int quiet;
  15static int verbose;
  16static int fetch_all;
  17static int depth;
  18static int no_progress;
  19static const char fetch_pack_usage[] =
  20"git-fetch-pack [--all] [--quiet|-q] [--keep|-k] [--thin] [--upload-pack=<git-upload-pack>] [--depth=<n>] [--no-progress] [-v] [<host>:]<directory> [<refs>...]";
  21static const char *uploadpack = "git-upload-pack";
  22
  23#define COMPLETE        (1U << 0)
  24#define COMMON          (1U << 1)
  25#define COMMON_REF      (1U << 2)
  26#define SEEN            (1U << 3)
  27#define POPPED          (1U << 4)
  28
  29/*
  30 * After sending this many "have"s if we do not get any new ACK , we
  31 * give up traversing our history.
  32 */
  33#define MAX_IN_VAIN 256
  34
  35static struct commit_list *rev_list;
  36static int non_common_revs, multi_ack, use_thin_pack, use_sideband;
  37
  38static void rev_list_push(struct commit *commit, int mark)
  39{
  40        if (!(commit->object.flags & mark)) {
  41                commit->object.flags |= mark;
  42
  43                if (!(commit->object.parsed))
  44                        parse_commit(commit);
  45
  46                insert_by_date(commit, &rev_list);
  47
  48                if (!(commit->object.flags & COMMON))
  49                        non_common_revs++;
  50        }
  51}
  52
  53static int rev_list_insert_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
  54{
  55        struct object *o = deref_tag(parse_object(sha1), path, 0);
  56
  57        if (o && o->type == OBJ_COMMIT)
  58                rev_list_push((struct commit *)o, SEEN);
  59
  60        return 0;
  61}
  62
  63/*
  64   This function marks a rev and its ancestors as common.
  65   In some cases, it is desirable to mark only the ancestors (for example
  66   when only the server does not yet know that they are common).
  67*/
  68
  69static void mark_common(struct commit *commit,
  70                int ancestors_only, int dont_parse)
  71{
  72        if (commit != NULL && !(commit->object.flags & COMMON)) {
  73                struct object *o = (struct object *)commit;
  74
  75                if (!ancestors_only)
  76                        o->flags |= COMMON;
  77
  78                if (!(o->flags & SEEN))
  79                        rev_list_push(commit, SEEN);
  80                else {
  81                        struct commit_list *parents;
  82
  83                        if (!ancestors_only && !(o->flags & POPPED))
  84                                non_common_revs--;
  85                        if (!o->parsed && !dont_parse)
  86                                parse_commit(commit);
  87
  88                        for (parents = commit->parents;
  89                                        parents;
  90                                        parents = parents->next)
  91                                mark_common(parents->item, 0, dont_parse);
  92                }
  93        }
  94}
  95
  96/*
  97  Get the next rev to send, ignoring the common.
  98*/
  99
 100static const unsigned char* get_rev(void)
 101{
 102        struct commit *commit = NULL;
 103
 104        while (commit == NULL) {
 105                unsigned int mark;
 106                struct commit_list* parents;
 107
 108                if (rev_list == NULL || non_common_revs == 0)
 109                        return NULL;
 110
 111                commit = rev_list->item;
 112                if (!(commit->object.parsed))
 113                        parse_commit(commit);
 114                commit->object.flags |= POPPED;
 115                if (!(commit->object.flags & COMMON))
 116                        non_common_revs--;
 117
 118                parents = commit->parents;
 119
 120                if (commit->object.flags & COMMON) {
 121                        /* do not send "have", and ignore ancestors */
 122                        commit = NULL;
 123                        mark = COMMON | SEEN;
 124                } else if (commit->object.flags & COMMON_REF)
 125                        /* send "have", and ignore ancestors */
 126                        mark = COMMON | SEEN;
 127                else
 128                        /* send "have", also for its ancestors */
 129                        mark = SEEN;
 130
 131                while (parents) {
 132                        if (!(parents->item->object.flags & SEEN))
 133                                rev_list_push(parents->item, mark);
 134                        if (mark & COMMON)
 135                                mark_common(parents->item, 1, 0);
 136                        parents = parents->next;
 137                }
 138
 139                rev_list = rev_list->next;
 140        }
 141
 142        return commit->object.sha1;
 143}
 144
 145static int find_common(int fd[2], unsigned char *result_sha1,
 146                       struct ref *refs)
 147{
 148        int fetching;
 149        int count = 0, flushes = 0, retval;
 150        const unsigned char *sha1;
 151        unsigned in_vain = 0;
 152        int got_continue = 0;
 153
 154        for_each_ref(rev_list_insert_ref, NULL);
 155
 156        fetching = 0;
 157        for ( ; refs ; refs = refs->next) {
 158                unsigned char *remote = refs->old_sha1;
 159                struct object *o;
 160
 161                /*
 162                 * If that object is complete (i.e. it is an ancestor of a
 163                 * local ref), we tell them we have it but do not have to
 164                 * tell them about its ancestors, which they already know
 165                 * about.
 166                 *
 167                 * We use lookup_object here because we are only
 168                 * interested in the case we *know* the object is
 169                 * reachable and we have already scanned it.
 170                 */
 171                if (((o = lookup_object(remote)) != NULL) &&
 172                                (o->flags & COMPLETE)) {
 173                        continue;
 174                }
 175
 176                if (!fetching)
 177                        packet_write(fd[1], "want %s%s%s%s%s%s%s\n",
 178                                     sha1_to_hex(remote),
 179                                     (multi_ack ? " multi_ack" : ""),
 180                                     (use_sideband == 2 ? " side-band-64k" : ""),
 181                                     (use_sideband == 1 ? " side-band" : ""),
 182                                     (use_thin_pack ? " thin-pack" : ""),
 183                                     (no_progress ? " no-progress" : ""),
 184                                     " ofs-delta");
 185                else
 186                        packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
 187                fetching++;
 188        }
 189        if (is_repository_shallow())
 190                write_shallow_commits(fd[1], 1);
 191        if (depth > 0)
 192                packet_write(fd[1], "deepen %d", depth);
 193        packet_flush(fd[1]);
 194        if (!fetching)
 195                return 1;
 196
 197        if (depth > 0) {
 198                char line[1024];
 199                unsigned char sha1[20];
 200                int len;
 201
 202                while ((len = packet_read_line(fd[0], line, sizeof(line)))) {
 203                        if (!prefixcmp(line, "shallow ")) {
 204                                if (get_sha1_hex(line + 8, sha1))
 205                                        die("invalid shallow line: %s", line);
 206                                register_shallow(sha1);
 207                                continue;
 208                        }
 209                        if (!prefixcmp(line, "unshallow ")) {
 210                                if (get_sha1_hex(line + 10, sha1))
 211                                        die("invalid unshallow line: %s", line);
 212                                if (!lookup_object(sha1))
 213                                        die("object not found: %s", line);
 214                                /* make sure that it is parsed as shallow */
 215                                parse_object(sha1);
 216                                if (unregister_shallow(sha1))
 217                                        die("no shallow found: %s", line);
 218                                continue;
 219                        }
 220                        die("expected shallow/unshallow, got %s", line);
 221                }
 222        }
 223
 224        flushes = 0;
 225        retval = -1;
 226        while ((sha1 = get_rev())) {
 227                packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
 228                if (verbose)
 229                        fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
 230                in_vain++;
 231                if (!(31 & ++count)) {
 232                        int ack;
 233
 234                        packet_flush(fd[1]);
 235                        flushes++;
 236
 237                        /*
 238                         * We keep one window "ahead" of the other side, and
 239                         * will wait for an ACK only on the next one
 240                         */
 241                        if (count == 32)
 242                                continue;
 243
 244                        do {
 245                                ack = get_ack(fd[0], result_sha1);
 246                                if (verbose && ack)
 247                                        fprintf(stderr, "got ack %d %s\n", ack,
 248                                                        sha1_to_hex(result_sha1));
 249                                if (ack == 1) {
 250                                        flushes = 0;
 251                                        multi_ack = 0;
 252                                        retval = 0;
 253                                        goto done;
 254                                } else if (ack == 2) {
 255                                        struct commit *commit =
 256                                                lookup_commit(result_sha1);
 257                                        mark_common(commit, 0, 1);
 258                                        retval = 0;
 259                                        in_vain = 0;
 260                                        got_continue = 1;
 261                                }
 262                        } while (ack);
 263                        flushes--;
 264                        if (got_continue && MAX_IN_VAIN < in_vain) {
 265                                if (verbose)
 266                                        fprintf(stderr, "giving up\n");
 267                                break; /* give up */
 268                        }
 269                }
 270        }
 271done:
 272        packet_write(fd[1], "done\n");
 273        if (verbose)
 274                fprintf(stderr, "done\n");
 275        if (retval != 0) {
 276                multi_ack = 0;
 277                flushes++;
 278        }
 279        while (flushes || multi_ack) {
 280                int ack = get_ack(fd[0], result_sha1);
 281                if (ack) {
 282                        if (verbose)
 283                                fprintf(stderr, "got ack (%d) %s\n", ack,
 284                                        sha1_to_hex(result_sha1));
 285                        if (ack == 1)
 286                                return 0;
 287                        multi_ack = 1;
 288                        continue;
 289                }
 290                flushes--;
 291        }
 292        return retval;
 293}
 294
 295static struct commit_list *complete;
 296
 297static int mark_complete(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 298{
 299        struct object *o = parse_object(sha1);
 300
 301        while (o && o->type == OBJ_TAG) {
 302                struct tag *t = (struct tag *) o;
 303                if (!t->tagged)
 304                        break; /* broken repository */
 305                o->flags |= COMPLETE;
 306                o = parse_object(t->tagged->sha1);
 307        }
 308        if (o && o->type == OBJ_COMMIT) {
 309                struct commit *commit = (struct commit *)o;
 310                commit->object.flags |= COMPLETE;
 311                insert_by_date(commit, &complete);
 312        }
 313        return 0;
 314}
 315
 316static void mark_recent_complete_commits(unsigned long cutoff)
 317{
 318        while (complete && cutoff <= complete->item->date) {
 319                if (verbose)
 320                        fprintf(stderr, "Marking %s as complete\n",
 321                                sha1_to_hex(complete->item->object.sha1));
 322                pop_most_recent_commit(&complete, COMPLETE);
 323        }
 324}
 325
 326static void filter_refs(struct ref **refs, int nr_match, char **match)
 327{
 328        struct ref **return_refs;
 329        struct ref *newlist = NULL;
 330        struct ref **newtail = &newlist;
 331        struct ref *ref, *next;
 332        struct ref *fastarray[32];
 333
 334        if (nr_match && !fetch_all) {
 335                if (ARRAY_SIZE(fastarray) < nr_match)
 336                        return_refs = xcalloc(nr_match, sizeof(struct ref *));
 337                else {
 338                        return_refs = fastarray;
 339                        memset(return_refs, 0, sizeof(struct ref *) * nr_match);
 340                }
 341        }
 342        else
 343                return_refs = NULL;
 344
 345        for (ref = *refs; ref; ref = next) {
 346                next = ref->next;
 347                if (!memcmp(ref->name, "refs/", 5) &&
 348                    check_ref_format(ref->name + 5))
 349                        ; /* trash */
 350                else if (fetch_all &&
 351                         (!depth || prefixcmp(ref->name, "refs/tags/") )) {
 352                        *newtail = ref;
 353                        ref->next = NULL;
 354                        newtail = &ref->next;
 355                        continue;
 356                }
 357                else {
 358                        int order = path_match(ref->name, nr_match, match);
 359                        if (order) {
 360                                return_refs[order-1] = ref;
 361                                continue; /* we will link it later */
 362                        }
 363                }
 364                free(ref);
 365        }
 366
 367        if (!fetch_all) {
 368                int i;
 369                for (i = 0; i < nr_match; i++) {
 370                        ref = return_refs[i];
 371                        if (ref) {
 372                                *newtail = ref;
 373                                ref->next = NULL;
 374                                newtail = &ref->next;
 375                        }
 376                }
 377                if (return_refs != fastarray)
 378                        free(return_refs);
 379        }
 380        *refs = newlist;
 381}
 382
 383static int everything_local(struct ref **refs, int nr_match, char **match)
 384{
 385        struct ref *ref;
 386        int retval;
 387        unsigned long cutoff = 0;
 388
 389        track_object_refs = 0;
 390        save_commit_buffer = 0;
 391
 392        for (ref = *refs; ref; ref = ref->next) {
 393                struct object *o;
 394
 395                o = parse_object(ref->old_sha1);
 396                if (!o)
 397                        continue;
 398
 399                /* We already have it -- which may mean that we were
 400                 * in sync with the other side at some time after
 401                 * that (it is OK if we guess wrong here).
 402                 */
 403                if (o->type == OBJ_COMMIT) {
 404                        struct commit *commit = (struct commit *)o;
 405                        if (!cutoff || cutoff < commit->date)
 406                                cutoff = commit->date;
 407                }
 408        }
 409
 410        if (!depth) {
 411                for_each_ref(mark_complete, NULL);
 412                if (cutoff)
 413                        mark_recent_complete_commits(cutoff);
 414        }
 415
 416        /*
 417         * Mark all complete remote refs as common refs.
 418         * Don't mark them common yet; the server has to be told so first.
 419         */
 420        for (ref = *refs; ref; ref = ref->next) {
 421                struct object *o = deref_tag(lookup_object(ref->old_sha1),
 422                                             NULL, 0);
 423
 424                if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
 425                        continue;
 426
 427                if (!(o->flags & SEEN)) {
 428                        rev_list_push((struct commit *)o, COMMON_REF | SEEN);
 429
 430                        mark_common((struct commit *)o, 1, 1);
 431                }
 432        }
 433
 434        filter_refs(refs, nr_match, match);
 435
 436        for (retval = 1, ref = *refs; ref ; ref = ref->next) {
 437                const unsigned char *remote = ref->old_sha1;
 438                unsigned char local[20];
 439                struct object *o;
 440
 441                o = lookup_object(remote);
 442                if (!o || !(o->flags & COMPLETE)) {
 443                        retval = 0;
 444                        if (!verbose)
 445                                continue;
 446                        fprintf(stderr,
 447                                "want %s (%s)\n", sha1_to_hex(remote),
 448                                ref->name);
 449                        continue;
 450                }
 451
 452                hashcpy(ref->new_sha1, local);
 453                if (!verbose)
 454                        continue;
 455                fprintf(stderr,
 456                        "already have %s (%s)\n", sha1_to_hex(remote),
 457                        ref->name);
 458        }
 459        return retval;
 460}
 461
 462static pid_t setup_sideband(int fd[2], int xd[2])
 463{
 464        pid_t side_pid;
 465
 466        if (!use_sideband) {
 467                fd[0] = xd[0];
 468                fd[1] = xd[1];
 469                return 0;
 470        }
 471        /* xd[] is talking with upload-pack; subprocess reads from
 472         * xd[0], spits out band#2 to stderr, and feeds us band#1
 473         * through our fd[0].
 474         */
 475        if (pipe(fd) < 0)
 476                die("fetch-pack: unable to set up pipe");
 477        side_pid = fork();
 478        if (side_pid < 0)
 479                die("fetch-pack: unable to fork off sideband demultiplexer");
 480        if (!side_pid) {
 481                /* subprocess */
 482                close(fd[0]);
 483                if (xd[0] != xd[1])
 484                        close(xd[1]);
 485                if (recv_sideband("fetch-pack", xd[0], fd[1], 2))
 486                        exit(1);
 487                exit(0);
 488        }
 489        close(xd[0]);
 490        close(fd[1]);
 491        fd[1] = xd[1];
 492        return side_pid;
 493}
 494
 495static int get_pack(int xd[2])
 496{
 497        int status;
 498        pid_t pid, side_pid;
 499        int fd[2];
 500        const char *argv[20];
 501        char keep_arg[256];
 502        char hdr_arg[256];
 503        const char **av;
 504        int do_keep = keep_pack;
 505
 506        side_pid = setup_sideband(fd, xd);
 507
 508        av = argv;
 509        *hdr_arg = 0;
 510        if (unpack_limit) {
 511                struct pack_header header;
 512
 513                if (read_pack_header(fd[0], &header))
 514                        die("protocol error: bad pack header");
 515                snprintf(hdr_arg, sizeof(hdr_arg), "--pack_header=%u,%u",
 516                         ntohl(header.hdr_version), ntohl(header.hdr_entries));
 517                if (ntohl(header.hdr_entries) < unpack_limit)
 518                        do_keep = 0;
 519                else
 520                        do_keep = 1;
 521        }
 522
 523        if (do_keep) {
 524                *av++ = "index-pack";
 525                *av++ = "--stdin";
 526                if (!quiet && !no_progress)
 527                        *av++ = "-v";
 528                if (use_thin_pack)
 529                        *av++ = "--fix-thin";
 530                if (keep_pack > 1 || unpack_limit) {
 531                        int s = sprintf(keep_arg,
 532                                        "--keep=fetch-pack %d on ", getpid());
 533                        if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
 534                                strcpy(keep_arg + s, "localhost");
 535                        *av++ = keep_arg;
 536                }
 537        }
 538        else {
 539                *av++ = "unpack-objects";
 540                if (quiet)
 541                        *av++ = "-q";
 542        }
 543        if (*hdr_arg)
 544                *av++ = hdr_arg;
 545        *av++ = NULL;
 546
 547        pid = fork();
 548        if (pid < 0)
 549                die("fetch-pack: unable to fork off %s", argv[0]);
 550        if (!pid) {
 551                dup2(fd[0], 0);
 552                close(fd[0]);
 553                close(fd[1]);
 554                execv_git_cmd(argv);
 555                die("%s exec failed", argv[0]);
 556        }
 557        close(fd[0]);
 558        close(fd[1]);
 559        while (waitpid(pid, &status, 0) < 0) {
 560                if (errno != EINTR)
 561                        die("waiting for %s: %s", argv[0], strerror(errno));
 562        }
 563        if (WIFEXITED(status)) {
 564                int code = WEXITSTATUS(status);
 565                if (code)
 566                        die("%s died with error code %d", argv[0], code);
 567                return 0;
 568        }
 569        if (WIFSIGNALED(status)) {
 570                int sig = WTERMSIG(status);
 571                die("%s died of signal %d", argv[0], sig);
 572        }
 573        die("%s died of unnatural causes %d", argv[0], status);
 574}
 575
 576static int fetch_pack(int fd[2], int nr_match, char **match)
 577{
 578        struct ref *ref;
 579        unsigned char sha1[20];
 580
 581        get_remote_heads(fd[0], &ref, 0, NULL, 0);
 582        if (is_repository_shallow() && !server_supports("shallow"))
 583                die("Server does not support shallow clients");
 584        if (server_supports("multi_ack")) {
 585                if (verbose)
 586                        fprintf(stderr, "Server supports multi_ack\n");
 587                multi_ack = 1;
 588        }
 589        if (server_supports("side-band-64k")) {
 590                if (verbose)
 591                        fprintf(stderr, "Server supports side-band-64k\n");
 592                use_sideband = 2;
 593        }
 594        else if (server_supports("side-band")) {
 595                if (verbose)
 596                        fprintf(stderr, "Server supports side-band\n");
 597                use_sideband = 1;
 598        }
 599        if (!ref) {
 600                packet_flush(fd[1]);
 601                die("no matching remote head");
 602        }
 603        if (everything_local(&ref, nr_match, match)) {
 604                packet_flush(fd[1]);
 605                goto all_done;
 606        }
 607        if (find_common(fd, sha1, ref) < 0)
 608                if (keep_pack != 1)
 609                        /* When cloning, it is not unusual to have
 610                         * no common commit.
 611                         */
 612                        fprintf(stderr, "warning: no common commits\n");
 613
 614        if (get_pack(fd))
 615                die("git-fetch-pack: fetch failed.");
 616
 617 all_done:
 618        while (ref) {
 619                printf("%s %s\n",
 620                       sha1_to_hex(ref->old_sha1), ref->name);
 621                ref = ref->next;
 622        }
 623        return 0;
 624}
 625
 626static int remove_duplicates(int nr_heads, char **heads)
 627{
 628        int src, dst;
 629
 630        for (src = dst = 0; src < nr_heads; src++) {
 631                /* If heads[src] is different from any of
 632                 * heads[0..dst], push it in.
 633                 */
 634                int i;
 635                for (i = 0; i < dst; i++) {
 636                        if (!strcmp(heads[i], heads[src]))
 637                                break;
 638                }
 639                if (i < dst)
 640                        continue;
 641                if (src != dst)
 642                        heads[dst] = heads[src];
 643                dst++;
 644        }
 645        heads[dst] = 0;
 646        return dst;
 647}
 648
 649static int fetch_pack_config(const char *var, const char *value)
 650{
 651        if (strcmp(var, "fetch.unpacklimit") == 0) {
 652                fetch_unpack_limit = git_config_int(var, value);
 653                return 0;
 654        }
 655
 656        if (strcmp(var, "transfer.unpacklimit") == 0) {
 657                transfer_unpack_limit = git_config_int(var, value);
 658                return 0;
 659        }
 660
 661        return git_default_config(var, value);
 662}
 663
 664static struct lock_file lock;
 665
 666int main(int argc, char **argv)
 667{
 668        int i, ret, nr_heads;
 669        char *dest = NULL, **heads;
 670        int fd[2];
 671        pid_t pid;
 672        struct stat st;
 673
 674        setup_git_directory();
 675        git_config(fetch_pack_config);
 676
 677        if (0 <= transfer_unpack_limit)
 678                unpack_limit = transfer_unpack_limit;
 679        else if (0 <= fetch_unpack_limit)
 680                unpack_limit = fetch_unpack_limit;
 681
 682        nr_heads = 0;
 683        heads = NULL;
 684        for (i = 1; i < argc; i++) {
 685                char *arg = argv[i];
 686
 687                if (*arg == '-') {
 688                        if (!prefixcmp(arg, "--upload-pack=")) {
 689                                uploadpack = arg + 14;
 690                                continue;
 691                        }
 692                        if (!prefixcmp(arg, "--exec=")) {
 693                                uploadpack = arg + 7;
 694                                continue;
 695                        }
 696                        if (!strcmp("--quiet", arg) || !strcmp("-q", arg)) {
 697                                quiet = 1;
 698                                continue;
 699                        }
 700                        if (!strcmp("--keep", arg) || !strcmp("-k", arg)) {
 701                                keep_pack++;
 702                                unpack_limit = 0;
 703                                continue;
 704                        }
 705                        if (!strcmp("--thin", arg)) {
 706                                use_thin_pack = 1;
 707                                continue;
 708                        }
 709                        if (!strcmp("--all", arg)) {
 710                                fetch_all = 1;
 711                                continue;
 712                        }
 713                        if (!strcmp("-v", arg)) {
 714                                verbose = 1;
 715                                continue;
 716                        }
 717                        if (!prefixcmp(arg, "--depth=")) {
 718                                depth = strtol(arg + 8, NULL, 0);
 719                                if (stat(git_path("shallow"), &st))
 720                                        st.st_mtime = 0;
 721                                continue;
 722                        }
 723                        if (!strcmp("--no-progress", arg)) {
 724                                no_progress = 1;
 725                                continue;
 726                        }
 727                        usage(fetch_pack_usage);
 728                }
 729                dest = arg;
 730                heads = argv + i + 1;
 731                nr_heads = argc - i - 1;
 732                break;
 733        }
 734        if (!dest)
 735                usage(fetch_pack_usage);
 736        pid = git_connect(fd, dest, uploadpack, verbose ? CONNECT_VERBOSE : 0);
 737        if (pid < 0)
 738                return 1;
 739        if (heads && nr_heads)
 740                nr_heads = remove_duplicates(nr_heads, heads);
 741        ret = fetch_pack(fd, nr_heads, heads);
 742        close(fd[0]);
 743        close(fd[1]);
 744        ret |= finish_connect(pid);
 745
 746        if (!ret && nr_heads) {
 747                /* If the heads to pull were given, we should have
 748                 * consumed all of them by matching the remote.
 749                 * Otherwise, 'git-fetch remote no-such-ref' would
 750                 * silently succeed without issuing an error.
 751                 */
 752                for (i = 0; i < nr_heads; i++)
 753                        if (heads[i] && heads[i][0]) {
 754                                error("no such remote ref %s", heads[i]);
 755                                ret = 1;
 756                        }
 757        }
 758
 759        if (!ret && depth > 0) {
 760                struct cache_time mtime;
 761                char *shallow = git_path("shallow");
 762                int fd;
 763
 764                mtime.sec = st.st_mtime;
 765#ifdef USE_NSEC
 766                mtime.usec = st.st_mtim.usec;
 767#endif
 768                if (stat(shallow, &st)) {
 769                        if (mtime.sec)
 770                                die("shallow file was removed during fetch");
 771                } else if (st.st_mtime != mtime.sec
 772#ifdef USE_NSEC
 773                                || st.st_mtim.usec != mtime.usec
 774#endif
 775                          )
 776                        die("shallow file was changed during fetch");
 777
 778                fd = hold_lock_file_for_update(&lock, shallow, 1);
 779                if (!write_shallow_commits(fd, 0)) {
 780                        unlink(shallow);
 781                        rollback_lock_file(&lock);
 782                } else {
 783                        close(fd);
 784                        commit_lock_file(&lock);
 785                }
 786        }
 787
 788        return !!ret;
 789}