fetch-pack.c

   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 #include "fetch-pack.h"
  10 #include "remote.h"
  11 #include "run-command.h"
  12 #include "transport.h"
  13 #include "version.h"
  14
  15 static int transfer_unpack_limit = -1;
  16 static int fetch_unpack_limit = -1;
  17 static int unpack_limit = 100;
  18 static int prefer_ofs_delta = 1;
  19 static int no_done;
  20 static int fetch_fsck_objects = -1;
  21 static int transfer_fsck_objects = -1;
  22 static int agent_supported;
  23
  24 #define COMPLETE        (1U << 0)
  25 #define COMMON          (1U << 1)
  26 #define COMMON_REF      (1U << 2)
  27 #define SEEN            (1U << 3)
  28 #define POPPED          (1U << 4)
  29
  30 static int marked;
  31
  32 /*
  33  * After sending this many "have"s if we do not get any new ACK , we
  34  * give up traversing our history.
  35  */
  36 #define MAX_IN_VAIN 256
  37
  38 static struct commit_list *rev_list;
  39 static int non_common_revs, multi_ack, use_sideband;
  40
  41 static void rev_list_push(struct commit *commit, int mark)
  42 {
  43         if (!(commit->object.flags & mark)) {
  44                 commit->object.flags |= mark;
  45
  46                 if (!(commit->object.parsed))
  47                         if (parse_commit(commit))
  48                                 return;
  49
  50                 commit_list_insert_by_date(commit, &rev_list);
  51
  52                 if (!(commit->object.flags & COMMON))
  53                         non_common_revs++;
  54         }
  55 }
  56
  57 static int rev_list_insert_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
  58 {
  59         struct object *o = deref_tag(parse_object(sha1), refname, 0);
  60
  61         if (o && o->type == OBJ_COMMIT)
  62                 rev_list_push((struct commit *)o, SEEN);
  63
  64         return 0;
  65 }
  66
  67 static int clear_marks(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
  68 {
  69         struct object *o = deref_tag(parse_object(sha1), refname, 0);
  70
  71         if (o && o->type == OBJ_COMMIT)
  72                 clear_commit_marks((struct commit *)o,
  73                                    COMMON | COMMON_REF | SEEN | POPPED);
  74         return 0;
  75 }
  76
  77 /*
  78    This function marks a rev and its ancestors as common.
  79    In some cases, it is desirable to mark only the ancestors (for example
  80    when only the server does not yet know that they are common).
  81 */
  82
  83 static void mark_common(struct commit *commit,
  84                 int ancestors_only, int dont_parse)
  85 {
  86         if (commit != NULL && !(commit->object.flags & COMMON)) {
  87                 struct object *o = (struct object *)commit;
  88
  89                 if (!ancestors_only)
  90                         o->flags |= COMMON;
  91
  92                 if (!(o->flags & SEEN))
  93                         rev_list_push(commit, SEEN);
  94                 else {
  95                         struct commit_list *parents;
  96
  97                         if (!ancestors_only && !(o->flags & POPPED))
  98                                 non_common_revs--;
  99                         if (!o->parsed && !dont_parse)
 100                                 if (parse_commit(commit))
 101                                         return;
 102
 103                         for (parents = commit->parents;
 104                                         parents;
 105                                         parents = parents->next)
 106                                 mark_common(parents->item, 0, dont_parse);
 107                 }
 108         }
 109 }
 110
 111 /*
 112   Get the next rev to send, ignoring the common.
 113 */
 114
 115 static const unsigned char *get_rev(void)
 116 {
 117         struct commit *commit = NULL;
 118
 119         while (commit == NULL) {
 120                 unsigned int mark;
 121                 struct commit_list *parents;
 122
 123                 if (rev_list == NULL || non_common_revs == 0)
 124                         return NULL;
 125
 126                 commit = rev_list->item;
 127                 if (!commit->object.parsed)
 128                         parse_commit(commit);
 129                 parents = commit->parents;
 130
 131                 commit->object.flags |= POPPED;
 132                 if (!(commit->object.flags & COMMON))
 133                         non_common_revs--;
 134
 135                 if (commit->object.flags & COMMON) {
 136                         /* do not send "have", and ignore ancestors */
 137                         commit = NULL;
 138                         mark = COMMON | SEEN;
 139                 } else if (commit->object.flags & COMMON_REF)
 140                         /* send "have", and ignore ancestors */
 141                         mark = COMMON | SEEN;
 142                 else
 143                         /* send "have", also for its ancestors */
 144                         mark = SEEN;
 145
 146                 while (parents) {
 147                         if (!(parents->item->object.flags & SEEN))
 148                                 rev_list_push(parents->item, mark);
 149                         if (mark & COMMON)
 150                                 mark_common(parents->item, 1, 0);
 151                         parents = parents->next;
 152                 }
 153
 154                 rev_list = rev_list->next;
 155         }
 156
 157         return commit->object.sha1;
 158 }
 159
 160 enum ack_type {
 161         NAK = 0,
 162         ACK,
 163         ACK_continue,
 164         ACK_common,
 165         ACK_ready
 166 };
 167
 168 static void consume_shallow_list(struct fetch_pack_args *args, int fd)
 169 {
 170         if (args->stateless_rpc && args->depth > 0) {
 171                 /* If we sent a depth we will get back "duplicate"
 172                  * shallow and unshallow commands every time there
 173                  * is a block of have lines exchanged.
 174                  */
 175                 char line[1000];
 176                 while (packet_read_line(fd, line, sizeof(line))) {
 177                         if (!prefixcmp(line, "shallow "))
 178                                 continue;
 179                         if (!prefixcmp(line, "unshallow "))
 180                                 continue;
 181                         die("git fetch-pack: expected shallow list");
 182                 }
 183         }
 184 }
 185
 186 struct write_shallow_data {
 187         struct strbuf *out;
 188         int use_pack_protocol;
 189         int count;
 190 };
 191
 192 static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
 193 {
 194         struct write_shallow_data *data = cb_data;
 195         const char *hex = sha1_to_hex(graft->sha1);
 196         data->count++;
 197         if (data->use_pack_protocol)
 198                 packet_buf_write(data->out, "shallow %s", hex);
 199         else {
 200                 strbuf_addstr(data->out, hex);
 201                 strbuf_addch(data->out, '\n');
 202         }
 203         return 0;
 204 }
 205
 206 static int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
 207 {
 208         struct write_shallow_data data;
 209         data.out = out;
 210         data.use_pack_protocol = use_pack_protocol;
 211         data.count = 0;
 212         for_each_commit_graft(write_one_shallow, &data);
 213         return data.count;
 214 }
 215
 216 static enum ack_type get_ack(int fd, unsigned char *result_sha1)
 217 {
 218         static char line[1000];
 219         int len = packet_read_line(fd, line, sizeof(line));
 220
 221         if (!len)
 222                 die("git fetch-pack: expected ACK/NAK, got EOF");
 223         if (line[len-1] == '\n')
 224                 line[--len] = 0;
 225         if (!strcmp(line, "NAK"))
 226                 return NAK;
 227         if (!prefixcmp(line, "ACK ")) {
 228                 if (!get_sha1_hex(line+4, result_sha1)) {
 229                         if (strstr(line+45, "continue"))
 230                                 return ACK_continue;
 231                         if (strstr(line+45, "common"))
 232                                 return ACK_common;
 233                         if (strstr(line+45, "ready"))
 234                                 return ACK_ready;
 235                         return ACK;
 236                 }
 237         }
 238         die("git fetch_pack: expected ACK/NAK, got '%s'", line);
 239 }
 240
 241 static void send_request(struct fetch_pack_args *args,
 242                          int fd, struct strbuf *buf)
 243 {
 244         if (args->stateless_rpc) {
 245                 send_sideband(fd, -1, buf->buf, buf->len, LARGE_PACKET_MAX);
 246                 packet_flush(fd);
 247         } else
 248                 safe_write(fd, buf->buf, buf->len);
 249 }
 250
 251 static void insert_one_alternate_ref(const struct ref *ref, void *unused)
 252 {
 253         rev_list_insert_ref(NULL, ref->old_sha1, 0, NULL);
 254 }
 255
 256 #define INITIAL_FLUSH 16
 257 #define PIPESAFE_FLUSH 32
 258 #define LARGE_FLUSH 1024
 259
 260 static int next_flush(struct fetch_pack_args *args, int count)
 261 {
 262         int flush_limit = args->stateless_rpc ? LARGE_FLUSH : PIPESAFE_FLUSH;
 263
 264         if (count < flush_limit)
 265                 count <<= 1;
 266         else
 267                 count += flush_limit;
 268         return count;
 269 }
 270
 271 static int find_common(struct fetch_pack_args *args,
 272                        int fd[2], unsigned char *result_sha1,
 273                        struct ref *refs)
 274 {
 275         int fetching;
 276         int count = 0, flushes = 0, flush_at = INITIAL_FLUSH, retval;
 277         const unsigned char *sha1;
 278         unsigned in_vain = 0;
 279         int got_continue = 0;
 280         int got_ready = 0;
 281         struct strbuf req_buf = STRBUF_INIT;
 282         size_t state_len = 0;
 283
 284         if (args->stateless_rpc && multi_ack == 1)
 285                 die("--stateless-rpc requires multi_ack_detailed");
 286         if (marked)
 287                 for_each_ref(clear_marks, NULL);
 288         marked = 1;
 289
 290         for_each_ref(rev_list_insert_ref, NULL);
 291         for_each_alternate_ref(insert_one_alternate_ref, NULL);
 292
 293         fetching = 0;
 294         for ( ; refs ; refs = refs->next) {
 295                 unsigned char *remote = refs->old_sha1;
 296                 const char *remote_hex;
 297                 struct object *o;
 298
 299                 /*
 300                  * If that object is complete (i.e. it is an ancestor of a
 301                  * local ref), we tell them we have it but do not have to
 302                  * tell them about its ancestors, which they already know
 303                  * about.
 304                  *
 305                  * We use lookup_object here because we are only
 306                  * interested in the case we *know* the object is
 307                  * reachable and we have already scanned it.
 308                  */
 309                 if (((o = lookup_object(remote)) != NULL) &&
 310                                 (o->flags & COMPLETE)) {
 311                         continue;
 312                 }
 313
 314                 remote_hex = sha1_to_hex(remote);
 315                 if (!fetching) {
 316                         struct strbuf c = STRBUF_INIT;
 317                         if (multi_ack == 2)     strbuf_addstr(&c, " multi_ack_detailed");
 318                         if (multi_ack == 1)     strbuf_addstr(&c, " multi_ack");
 319                         if (no_done)            strbuf_addstr(&c, " no-done");
 320                         if (use_sideband == 2)  strbuf_addstr(&c, " side-band-64k");
 321                         if (use_sideband == 1)  strbuf_addstr(&c, " side-band");
 322                         if (args->use_thin_pack) strbuf_addstr(&c, " thin-pack");
 323                         if (args->no_progress)   strbuf_addstr(&c, " no-progress");
 324                         if (args->include_tag)   strbuf_addstr(&c, " include-tag");
 325                         if (prefer_ofs_delta)   strbuf_addstr(&c, " ofs-delta");
 326                         if (agent_supported)    strbuf_addf(&c, " agent=%s",
 327                                                             git_user_agent_sanitized());
 328                         packet_buf_write(&req_buf, "want %s%s\n", remote_hex, c.buf);
 329                         strbuf_release(&c);
 330                 } else
 331                         packet_buf_write(&req_buf, "want %s\n", remote_hex);
 332                 fetching++;
 333         }
 334
 335         if (!fetching) {
 336                 strbuf_release(&req_buf);
 337                 packet_flush(fd[1]);
 338                 return 1;
 339         }
 340
 341         if (is_repository_shallow())
 342                 write_shallow_commits(&req_buf, 1);
 343         if (args->depth > 0)
 344                 packet_buf_write(&req_buf, "deepen %d", args->depth);
 345         packet_buf_flush(&req_buf);
 346         state_len = req_buf.len;
 347
 348         if (args->depth > 0) {
 349                 char line[1024];
 350                 unsigned char sha1[20];
 351
 352                 send_request(args, fd[1], &req_buf);
 353                 while (packet_read_line(fd[0], line, sizeof(line))) {
 354                         if (!prefixcmp(line, "shallow ")) {
 355                                 if (get_sha1_hex(line + 8, sha1))
 356                                         die("invalid shallow line: %s", line);
 357                                 register_shallow(sha1);
 358                                 continue;
 359                         }
 360                         if (!prefixcmp(line, "unshallow ")) {
 361                                 if (get_sha1_hex(line + 10, sha1))
 362                                         die("invalid unshallow line: %s", line);
 363                                 if (!lookup_object(sha1))
 364                                         die("object not found: %s", line);
 365                                 /* make sure that it is parsed as shallow */
 366                                 if (!parse_object(sha1))
 367                                         die("error in object: %s", line);
 368                                 if (unregister_shallow(sha1))
 369                                         die("no shallow found: %s", line);
 370                                 continue;
 371                         }
 372                         die("expected shallow/unshallow, got %s", line);
 373                 }
 374         } else if (!args->stateless_rpc)
 375                 send_request(args, fd[1], &req_buf);
 376
 377         if (!args->stateless_rpc) {
 378                 /* If we aren't using the stateless-rpc interface
 379                  * we don't need to retain the headers.
 380                  */
 381                 strbuf_setlen(&req_buf, 0);
 382                 state_len = 0;
 383         }
 384
 385         flushes = 0;
 386         retval = -1;
 387         while ((sha1 = get_rev())) {
 388                 packet_buf_write(&req_buf, "have %s\n", sha1_to_hex(sha1));
 389                 if (args->verbose)
 390                         fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
 391                 in_vain++;
 392                 if (flush_at <= ++count) {
 393                         int ack;
 394
 395                         packet_buf_flush(&req_buf);
 396                         send_request(args, fd[1], &req_buf);
 397                         strbuf_setlen(&req_buf, state_len);
 398                         flushes++;
 399                         flush_at = next_flush(args, count);
 400
 401                         /*
 402                          * We keep one window "ahead" of the other side, and
 403                          * will wait for an ACK only on the next one
 404                          */
 405                         if (!args->stateless_rpc && count == INITIAL_FLUSH)
 406                                 continue;
 407
 408                         consume_shallow_list(args, fd[0]);
 409                         do {
 410                                 ack = get_ack(fd[0], result_sha1);
 411                                 if (args->verbose && ack)
 412                                         fprintf(stderr, "got ack %d %s\n", ack,
 413                                                         sha1_to_hex(result_sha1));
 414                                 switch (ack) {
 415                                 case ACK:
 416                                         flushes = 0;
 417                                         multi_ack = 0;
 418                                         retval = 0;
 419                                         goto done;
 420                                 case ACK_common:
 421                                 case ACK_ready:
 422                                 case ACK_continue: {
 423                                         struct commit *commit =
 424                                                 lookup_commit(result_sha1);
 425                                         if (!commit)
 426                                                 die("invalid commit %s", sha1_to_hex(result_sha1));
 427                                         if (args->stateless_rpc
 428                                          && ack == ACK_common
 429                                          && !(commit->object.flags & COMMON)) {
 430                                                 /* We need to replay the have for this object
 431                                                  * on the next RPC request so the peer knows
 432                                                  * it is in common with us.
 433                                                  */
 434                                                 const char *hex = sha1_to_hex(result_sha1);
 435                                                 packet_buf_write(&req_buf, "have %s\n", hex);
 436                                                 state_len = req_buf.len;
 437                                         }
 438                                         mark_common(commit, 0, 1);
 439                                         retval = 0;
 440                                         in_vain = 0;
 441                                         got_continue = 1;
 442                                         if (ack == ACK_ready) {
 443                                                 rev_list = NULL;
 444                                                 got_ready = 1;
 445                                         }
 446                                         break;
 447                                         }
 448                                 }
 449                         } while (ack);
 450                         flushes--;
 451                         if (got_continue && MAX_IN_VAIN < in_vain) {
 452                                 if (args->verbose)
 453                                         fprintf(stderr, "giving up\n");
 454                                 break; /* give up */
 455                         }
 456                 }
 457         }
 458 done:
 459         if (!got_ready || !no_done) {
 460                 packet_buf_write(&req_buf, "done\n");
 461                 send_request(args, fd[1], &req_buf);
 462         }
 463         if (args->verbose)
 464                 fprintf(stderr, "done\n");
 465         if (retval != 0) {
 466                 multi_ack = 0;
 467                 flushes++;
 468         }
 469         strbuf_release(&req_buf);
 470
 471         consume_shallow_list(args, fd[0]);
 472         while (flushes || multi_ack) {
 473                 int ack = get_ack(fd[0], result_sha1);
 474                 if (ack) {
 475                         if (args->verbose)
 476                                 fprintf(stderr, "got ack (%d) %s\n", ack,
 477                                         sha1_to_hex(result_sha1));
 478                         if (ack == ACK)
 479                                 return 0;
 480                         multi_ack = 1;
 481                         continue;
 482                 }
 483                 flushes--;
 484         }
 485         /* it is no error to fetch into a completely empty repo */
 486         return count ? retval : 0;
 487 }
 488
 489 static struct commit_list *complete;
 490
 491 static int mark_complete(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
 492 {
 493         struct object *o = parse_object(sha1);
 494
 495         while (o && o->type == OBJ_TAG) {
 496                 struct tag *t = (struct tag *) o;
 497                 if (!t->tagged)
 498                         break; /* broken repository */
 499                 o->flags |= COMPLETE;
 500                 o = parse_object(t->tagged->sha1);
 501         }
 502         if (o && o->type == OBJ_COMMIT) {
 503                 struct commit *commit = (struct commit *)o;
 504                 if (!(commit->object.flags & COMPLETE)) {
 505                         commit->object.flags |= COMPLETE;
 506                         commit_list_insert_by_date(commit, &complete);
 507                 }
 508         }
 509         return 0;
 510 }
 511
 512 static void mark_recent_complete_commits(struct fetch_pack_args *args,
 513                                          unsigned long cutoff)
 514 {
 515         while (complete && cutoff <= complete->item->date) {
 516                 if (args->verbose)
 517                         fprintf(stderr, "Marking %s as complete\n",
 518                                 sha1_to_hex(complete->item->object.sha1));
 519                 pop_most_recent_commit(&complete, COMPLETE);
 520         }
 521 }
 522
 523 static int non_matching_ref(struct string_list_item *item, void *unused)
 524 {
 525         if (item->util) {
 526                 item->util = NULL;
 527                 return 0;
 528         }
 529         else
 530                 return 1;
 531 }
 532
 533 static void filter_refs(struct fetch_pack_args *args,
 534                         struct ref **refs, struct string_list *sought)
 535 {
 536         struct ref *newlist = NULL;
 537         struct ref **newtail = &newlist;
 538         struct ref *ref, *next;
 539         int sought_pos;
 540
 541         sought_pos = 0;
 542         for (ref = *refs; ref; ref = next) {
 543                 int keep = 0;
 544                 next = ref->next;
 545                 if (!memcmp(ref->name, "refs/", 5) &&
 546                     check_refname_format(ref->name + 5, 0))
 547                         ; /* trash */
 548                 else {
 549                         while (sought_pos < sought->nr) {
 550                                 int cmp = strcmp(ref->name, sought->items[sought_pos].string);
 551                                 if (cmp < 0)
 552                                         break; /* definitely do not have it */
 553                                 else if (cmp == 0) {
 554                                         keep = 1; /* definitely have it */
 555                                         sought->items[sought_pos++].util = "matched";
 556                                         break;
 557                                 }
 558                                 else
 559                                         sought_pos++; /* might have it; keep looking */
 560                         }
 561                 }
 562
 563                 if (! keep && args->fetch_all &&
 564                     (!args->depth || prefixcmp(ref->name, "refs/tags/")))
 565                         keep = 1;
 566
 567                 if (keep) {
 568                         *newtail = ref;
 569                         ref->next = NULL;
 570                         newtail = &ref->next;
 571                 } else {
 572                         free(ref);
 573                 }
 574         }
 575
 576         filter_string_list(sought, 0, non_matching_ref, NULL);
 577         *refs = newlist;
 578 }
 579
 580 static void mark_alternate_complete(const struct ref *ref, void *unused)
 581 {
 582         mark_complete(NULL, ref->old_sha1, 0, NULL);
 583 }
 584
 585 static int everything_local(struct fetch_pack_args *args,
 586                             struct ref **refs, struct string_list *sought)
 587 {
 588         struct ref *ref;
 589         int retval;
 590         unsigned long cutoff = 0;
 591
 592         save_commit_buffer = 0;
 593
 594         for (ref = *refs; ref; ref = ref->next) {
 595                 struct object *o;
 596
 597                 o = parse_object(ref->old_sha1);
 598                 if (!o)
 599                         continue;
 600
 601                 /* We already have it -- which may mean that we were
 602                  * in sync with the other side at some time after
 603                  * that (it is OK if we guess wrong here).
 604                  */
 605                 if (o->type == OBJ_COMMIT) {
 606                         struct commit *commit = (struct commit *)o;
 607                         if (!cutoff || cutoff < commit->date)
 608                                 cutoff = commit->date;
 609                 }
 610         }
 611
 612         if (!args->depth) {
 613                 for_each_ref(mark_complete, NULL);
 614                 for_each_alternate_ref(mark_alternate_complete, NULL);
 615                 if (cutoff)
 616                         mark_recent_complete_commits(args, cutoff);
 617         }
 618
 619         /*
 620          * Mark all complete remote refs as common refs.
 621          * Don't mark them common yet; the server has to be told so first.
 622          */
 623         for (ref = *refs; ref; ref = ref->next) {
 624                 struct object *o = deref_tag(lookup_object(ref->old_sha1),
 625                                              NULL, 0);
 626
 627                 if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
 628                         continue;
 629
 630                 if (!(o->flags & SEEN)) {
 631                         rev_list_push((struct commit *)o, COMMON_REF | SEEN);
 632
 633                         mark_common((struct commit *)o, 1, 1);
 634                 }
 635         }
 636
 637         filter_refs(args, refs, sought);
 638
 639         for (retval = 1, ref = *refs; ref ; ref = ref->next) {
 640                 const unsigned char *remote = ref->old_sha1;
 641                 unsigned char local[20];
 642                 struct object *o;
 643
 644                 o = lookup_object(remote);
 645                 if (!o || !(o->flags & COMPLETE)) {
 646                         retval = 0;
 647                         if (!args->verbose)
 648                                 continue;
 649                         fprintf(stderr,
 650                                 "want %s (%s)\n", sha1_to_hex(remote),
 651                                 ref->name);
 652                         continue;
 653                 }
 654
 655                 hashcpy(ref->new_sha1, local);
 656                 if (!args->verbose)
 657                         continue;
 658                 fprintf(stderr,
 659                         "already have %s (%s)\n", sha1_to_hex(remote),
 660                         ref->name);
 661         }
 662         return retval;
 663 }
 664
 665 static int sideband_demux(int in, int out, void *data)
 666 {
 667         int *xd = data;
 668
 669         int ret = recv_sideband("fetch-pack", xd[0], out);
 670         close(out);
 671         return ret;
 672 }
 673
 674 static int get_pack(struct fetch_pack_args *args,
 675                     int xd[2], char **pack_lockfile)
 676 {
 677         struct async demux;
 678         const char *argv[20];
 679         char keep_arg[256];
 680         char hdr_arg[256];
 681         const char **av;
 682         int do_keep = args->keep_pack;
 683         struct child_process cmd;
 684
 685         memset(&demux, 0, sizeof(demux));
 686         if (use_sideband) {
 687                 /* xd[] is talking with upload-pack; subprocess reads from
 688                  * xd[0], spits out band#2 to stderr, and feeds us band#1
 689                  * through demux->out.
 690                  */
 691                 demux.proc = sideband_demux;
 692                 demux.data = xd;
 693                 demux.out = -1;
 694                 if (start_async(&demux))
 695                         die("fetch-pack: unable to fork off sideband"
 696                             " demultiplexer");
 697         }
 698         else
 699                 demux.out = xd[0];
 700
 701         memset(&cmd, 0, sizeof(cmd));
 702         cmd.argv = argv;
 703         av = argv;
 704         *hdr_arg = 0;
 705         if (!args->keep_pack && unpack_limit) {
 706                 struct pack_header header;
 707
 708                 if (read_pack_header(demux.out, &header))
 709                         die("protocol error: bad pack header");
 710                 snprintf(hdr_arg, sizeof(hdr_arg),
 711                          "--pack_header=%"PRIu32",%"PRIu32,
 712                          ntohl(header.hdr_version), ntohl(header.hdr_entries));
 713                 if (ntohl(header.hdr_entries) < unpack_limit)
 714                         do_keep = 0;
 715                 else
 716                         do_keep = 1;
 717         }
 718
 719         if (do_keep) {
 720                 if (pack_lockfile)
 721                         cmd.out = -1;
 722                 *av++ = "index-pack";
 723                 *av++ = "--stdin";
 724                 if (!args->quiet && !args->no_progress)
 725                         *av++ = "-v";
 726                 if (args->use_thin_pack)
 727                         *av++ = "--fix-thin";
 728                 if (args->lock_pack || unpack_limit) {
 729                         int s = sprintf(keep_arg,
 730                                         "--keep=fetch-pack %"PRIuMAX " on ", (uintmax_t) getpid());
 731                         if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
 732                                 strcpy(keep_arg + s, "localhost");
 733                         *av++ = keep_arg;
 734                 }
 735         }
 736         else {
 737                 *av++ = "unpack-objects";
 738                 if (args->quiet || args->no_progress)
 739                         *av++ = "-q";
 740         }
 741         if (*hdr_arg)
 742                 *av++ = hdr_arg;
 743         if (fetch_fsck_objects >= 0
 744             ? fetch_fsck_objects
 745             : transfer_fsck_objects >= 0
 746             ? transfer_fsck_objects
 747             : 0)
 748                 *av++ = "--strict";
 749         *av++ = NULL;
 750
 751         cmd.in = demux.out;
 752         cmd.git_cmd = 1;
 753         if (start_command(&cmd))
 754                 die("fetch-pack: unable to fork off %s", argv[0]);
 755         if (do_keep && pack_lockfile) {
 756                 *pack_lockfile = index_pack_lockfile(cmd.out);
 757                 close(cmd.out);
 758         }
 759
 760         if (finish_command(&cmd))
 761                 die("%s failed", argv[0]);
 762         if (use_sideband && finish_async(&demux))
 763                 die("error in sideband demultiplexer");
 764         return 0;
 765 }
 766
 767 static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 768                                  int fd[2],
 769                                  const struct ref *orig_ref,
 770                                  struct string_list *sought,
 771                                  char **pack_lockfile)
 772 {
 773         struct ref *ref = copy_ref_list(orig_ref);
 774         unsigned char sha1[20];
 775         const char *agent_feature;
 776         int agent_len;
 777
 778         sort_ref_list(&ref, ref_compare_name);
 779
 780         if (is_repository_shallow() && !server_supports("shallow"))
 781                 die("Server does not support shallow clients");
 782         if (server_supports("multi_ack_detailed")) {
 783                 if (args->verbose)
 784                         fprintf(stderr, "Server supports multi_ack_detailed\n");
 785                 multi_ack = 2;
 786                 if (server_supports("no-done")) {
 787                         if (args->verbose)
 788                                 fprintf(stderr, "Server supports no-done\n");
 789                         if (args->stateless_rpc)
 790                                 no_done = 1;
 791                 }
 792         }
 793         else if (server_supports("multi_ack")) {
 794                 if (args->verbose)
 795                         fprintf(stderr, "Server supports multi_ack\n");
 796                 multi_ack = 1;
 797         }
 798         if (server_supports("side-band-64k")) {
 799                 if (args->verbose)
 800                         fprintf(stderr, "Server supports side-band-64k\n");
 801                 use_sideband = 2;
 802         }
 803         else if (server_supports("side-band")) {
 804                 if (args->verbose)
 805                         fprintf(stderr, "Server supports side-band\n");
 806                 use_sideband = 1;
 807         }
 808         if (!server_supports("thin-pack"))
 809                 args->use_thin_pack = 0;
 810         if (!server_supports("no-progress"))
 811                 args->no_progress = 0;
 812         if (!server_supports("include-tag"))
 813                 args->include_tag = 0;
 814         if (server_supports("ofs-delta")) {
 815                 if (args->verbose)
 816                         fprintf(stderr, "Server supports ofs-delta\n");
 817         } else
 818                 prefer_ofs_delta = 0;
 819
 820         if ((agent_feature = server_feature_value("agent", &agent_len))) {
 821                 agent_supported = 1;
 822                 if (args->verbose && agent_len)
 823                         fprintf(stderr, "Server version is %.*s\n",
 824                                 agent_len, agent_feature);
 825         }
 826
 827         if (everything_local(args, &ref, sought)) {
 828                 packet_flush(fd[1]);
 829                 goto all_done;
 830         }
 831         if (find_common(args, fd, sha1, ref) < 0)
 832                 if (!args->keep_pack)
 833                         /* When cloning, it is not unusual to have
 834                          * no common commit.
 835                          */
 836                         warning("no common commits");
 837
 838         if (args->stateless_rpc)
 839                 packet_flush(fd[1]);
 840         if (get_pack(args, fd, pack_lockfile))
 841                 die("git fetch-pack: fetch failed.");
 842
 843  all_done:
 844         return ref;
 845 }
 846
 847 static int fetch_pack_config(const char *var, const char *value, void *cb)
 848 {
 849         if (strcmp(var, "fetch.unpacklimit") == 0) {
 850                 fetch_unpack_limit = git_config_int(var, value);
 851                 return 0;
 852         }
 853
 854         if (strcmp(var, "transfer.unpacklimit") == 0) {
 855                 transfer_unpack_limit = git_config_int(var, value);
 856                 return 0;
 857         }
 858
 859         if (strcmp(var, "repack.usedeltabaseoffset") == 0) {
 860                 prefer_ofs_delta = git_config_bool(var, value);
 861                 return 0;
 862         }
 863
 864         if (!strcmp(var, "fetch.fsckobjects")) {
 865                 fetch_fsck_objects = git_config_bool(var, value);
 866                 return 0;
 867         }
 868
 869         if (!strcmp(var, "transfer.fsckobjects")) {
 870                 transfer_fsck_objects = git_config_bool(var, value);
 871                 return 0;
 872         }
 873
 874         return git_default_config(var, value, cb);
 875 }
 876
 877 static struct lock_file lock;
 878
 879 static void fetch_pack_setup(void)
 880 {
 881         static int did_setup;
 882         if (did_setup)
 883                 return;
 884         git_config(fetch_pack_config, NULL);
 885         if (0 <= transfer_unpack_limit)
 886                 unpack_limit = transfer_unpack_limit;
 887         else if (0 <= fetch_unpack_limit)
 888                 unpack_limit = fetch_unpack_limit;
 889         did_setup = 1;
 890 }
 891
 892 struct ref *fetch_pack(struct fetch_pack_args *args,
 893                        int fd[], struct child_process *conn,
 894                        const struct ref *ref,
 895                        const char *dest,
 896                        struct string_list *sought,
 897                        char **pack_lockfile)
 898 {
 899         struct stat st;
 900         struct ref *ref_cpy;
 901
 902         fetch_pack_setup();
 903         if (args->depth > 0) {
 904                 if (stat(git_path("shallow"), &st))
 905                         st.st_mtime = 0;
 906         }
 907
 908         if (sought->nr) {
 909                 sort_string_list(sought);
 910                 string_list_remove_duplicates(sought, 0);
 911         }
 912
 913         if (!ref) {
 914                 packet_flush(fd[1]);
 915                 die("no matching remote head");
 916         }
 917         ref_cpy = do_fetch_pack(args, fd, ref, sought, pack_lockfile);
 918
 919         if (args->depth > 0) {
 920                 struct cache_time mtime;
 921                 struct strbuf sb = STRBUF_INIT;
 922                 char *shallow = git_path("shallow");
 923                 int fd;
 924
 925                 mtime.sec = st.st_mtime;
 926                 mtime.nsec = ST_MTIME_NSEC(st);
 927                 if (stat(shallow, &st)) {
 928                         if (mtime.sec)
 929                                 die("shallow file was removed during fetch");
 930                 } else if (st.st_mtime != mtime.sec
 931 #ifdef USE_NSEC
 932                                 || ST_MTIME_NSEC(st) != mtime.nsec
 933 #endif
 934                           )
 935                         die("shallow file was changed during fetch");
 936
 937                 fd = hold_lock_file_for_update(&lock, shallow,
 938                                                LOCK_DIE_ON_ERROR);
 939                 if (!write_shallow_commits(&sb, 0)
 940                  || write_in_full(fd, sb.buf, sb.len) != sb.len) {
 941                         unlink_or_warn(shallow);
 942                         rollback_lock_file(&lock);
 943                 } else {
 944                         commit_lock_file(&lock);
 945                 }
 946                 strbuf_release(&sb);
 947         }
 948
 949         reprepare_packed_git();
 950         return ref_cpy;
 951 }