git.oblomov.eu Git - git/blob - http-walker.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "walker.h"
   4 #include "http.h"
   5
   6 #define PREV_BUF_SIZE 4096
   7
   8 struct alt_base
   9 {
  10         char *base;
  11         int got_indices;
  12         struct packed_git *packs;
  13         struct alt_base *next;
  14 };
  15
  16 enum object_request_state {
  17         WAITING,
  18         ABORTED,
  19         ACTIVE,
  20         COMPLETE,
  21 };
  22
  23 struct object_request
  24 {
  25         struct walker *walker;
  26         unsigned char sha1[20];
  27         struct alt_base *repo;
  28         char *url;
  29         char filename[PATH_MAX];
  30         char tmpfile[PATH_MAX];
  31         int local;
  32         enum object_request_state state;
  33         CURLcode curl_result;
  34         char errorstr[CURL_ERROR_SIZE];
  35         long http_code;
  36         unsigned char real_sha1[20];
  37         git_SHA_CTX c;
  38         z_stream stream;
  39         int zret;
  40         int rename;
  41         struct active_request_slot *slot;
  42         struct object_request *next;
  43 };
  44
  45 struct alternates_request {
  46         struct walker *walker;
  47         const char *base;
  48         char *url;
  49         struct strbuf *buffer;
  50         struct active_request_slot *slot;
  51         int http_specific;
  52 };
  53
  54 struct walker_data {
  55         const char *url;
  56         int got_alternates;
  57         struct alt_base *alt;
  58 };
  59
  60 static struct object_request *object_queue_head;
  61
  62 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
  63                                void *data)
  64 {
  65         unsigned char expn[4096];
  66         size_t size = eltsize * nmemb;
  67         int posn = 0;
  68         struct object_request *obj_req = (struct object_request *)data;
  69         do {
  70                 ssize_t retval = xwrite(obj_req->local,
  71                                         (char *) ptr + posn, size - posn);
  72                 if (retval < 0)
  73                         return posn;
  74                 posn += retval;
  75         } while (posn < size);
  76
  77         obj_req->stream.avail_in = size;
  78         obj_req->stream.next_in = ptr;
  79         do {
  80                 obj_req->stream.next_out = expn;
  81                 obj_req->stream.avail_out = sizeof(expn);
  82                 obj_req->zret = git_inflate(&obj_req->stream, Z_SYNC_FLUSH);
  83                 git_SHA1_Update(&obj_req->c, expn,
  84                                 sizeof(expn) - obj_req->stream.avail_out);
  85         } while (obj_req->stream.avail_in && obj_req->zret == Z_OK);
  86         data_received++;
  87         return size;
  88 }
  89
  90 static void fetch_alternates(struct walker *walker, const char *base);
  91
  92 static void process_object_response(void *callback_data);
  93
  94 static void start_object_request(struct walker *walker,
  95                                  struct object_request *obj_req)
  96 {
  97         char *hex = sha1_to_hex(obj_req->sha1);
  98         char prevfile[PATH_MAX];
  99         char *url;
 100         char *posn;
 101         int prevlocal;
 102         unsigned char prev_buf[PREV_BUF_SIZE];
 103         ssize_t prev_read = 0;
 104         long prev_posn = 0;
 105         char range[RANGE_HEADER_SIZE];
 106         struct curl_slist *range_header = NULL;
 107         struct active_request_slot *slot;
 108
 109         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
 110         unlink_or_warn(prevfile);
 111         rename(obj_req->tmpfile, prevfile);
 112         unlink_or_warn(obj_req->tmpfile);
 113
 114         if (obj_req->local != -1)
 115                 error("fd leakage in start: %d", obj_req->local);
 116         obj_req->local = open(obj_req->tmpfile,
 117                               O_WRONLY | O_CREAT | O_EXCL, 0666);
 118         /*
 119          * This could have failed due to the "lazy directory creation";
 120          * try to mkdir the last path component.
 121          */
 122         if (obj_req->local < 0 && errno == ENOENT) {
 123                 char *dir = strrchr(obj_req->tmpfile, '/');
 124                 if (dir) {
 125                         *dir = 0;
 126                         mkdir(obj_req->tmpfile, 0777);
 127                         *dir = '/';
 128                 }
 129                 obj_req->local = open(obj_req->tmpfile,
 130                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
 131         }
 132
 133         if (obj_req->local < 0) {
 134                 obj_req->state = ABORTED;
 135                 error("Couldn't create temporary file %s for %s: %s",
 136                       obj_req->tmpfile, obj_req->filename, strerror(errno));
 137                 return;
 138         }
 139
 140         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 141
 142         git_inflate_init(&obj_req->stream);
 143
 144         git_SHA1_Init(&obj_req->c);
 145
 146         url = xmalloc(strlen(obj_req->repo->base) + 51);
 147         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 51);
 148         strcpy(url, obj_req->repo->base);
 149         posn = url + strlen(obj_req->repo->base);
 150         strcpy(posn, "/objects/");
 151         posn += 9;
 152         memcpy(posn, hex, 2);
 153         posn += 2;
 154         *(posn++) = '/';
 155         strcpy(posn, hex + 2);
 156         strcpy(obj_req->url, url);
 157
 158         /*
 159          * If a previous temp file is present, process what was already
 160          * fetched.
 161          */
 162         prevlocal = open(prevfile, O_RDONLY);
 163         if (prevlocal != -1) {
 164                 do {
 165                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
 166                         if (prev_read>0) {
 167                                 if (fwrite_sha1_file(prev_buf,
 168                                                      1,
 169                                                      prev_read,
 170                                                      obj_req) == prev_read)
 171                                         prev_posn += prev_read;
 172                                 else
 173                                         prev_read = -1;
 174                         }
 175                 } while (prev_read > 0);
 176                 close(prevlocal);
 177         }
 178         unlink_or_warn(prevfile);
 179
 180         /*
 181          * Reset inflate/SHA1 if there was an error reading the previous temp
 182          * file; also rewind to the beginning of the local file.
 183          */
 184         if (prev_read == -1) {
 185                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 186                 git_inflate_init(&obj_req->stream);
 187                 git_SHA1_Init(&obj_req->c);
 188                 if (prev_posn>0) {
 189                         prev_posn = 0;
 190                         lseek(obj_req->local, 0, SEEK_SET);
 191                         ftruncate(obj_req->local, 0);
 192                 }
 193         }
 194
 195         slot = get_active_slot();
 196         slot->callback_func = process_object_response;
 197         slot->callback_data = obj_req;
 198         obj_req->slot = slot;
 199
 200         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
 201         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
 202         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
 203         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 204         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 205
 206         /*
 207          * If we have successfully processed data from a previous fetch
 208          * attempt, only fetch the data we don't already have.
 209          */
 210         if (prev_posn>0) {
 211                 if (walker->get_verbosely)
 212                         fprintf(stderr,
 213                                 "Resuming fetch of object %s at byte %ld\n",
 214                                 hex, prev_posn);
 215                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 216                 range_header = curl_slist_append(range_header, range);
 217                 curl_easy_setopt(slot->curl,
 218                                  CURLOPT_HTTPHEADER, range_header);
 219         }
 220
 221         /* Try to get the request started, abort the request on error */
 222         obj_req->state = ACTIVE;
 223         if (!start_active_slot(slot)) {
 224                 obj_req->state = ABORTED;
 225                 obj_req->slot = NULL;
 226                 close(obj_req->local);
 227                 obj_req->local = -1;
 228                 free(obj_req->url);
 229                 return;
 230         }
 231 }
 232
 233 static void finish_object_request(struct object_request *obj_req)
 234 {
 235         struct stat st;
 236
 237         close(obj_req->local);
 238         obj_req->local = -1;
 239
 240         if (obj_req->http_code == 416) {
 241                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 242         } else if (obj_req->curl_result != CURLE_OK) {
 243                 if (stat(obj_req->tmpfile, &st) == 0)
 244                         if (st.st_size == 0)
 245                                 unlink_or_warn(obj_req->tmpfile);
 246                 return;
 247         }
 248
 249         git_inflate_end(&obj_req->stream);
 250         git_SHA1_Final(obj_req->real_sha1, &obj_req->c);
 251         if (obj_req->zret != Z_STREAM_END) {
 252                 unlink_or_warn(obj_req->tmpfile);
 253                 return;
 254         }
 255         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 256                 unlink_or_warn(obj_req->tmpfile);
 257                 return;
 258         }
 259         obj_req->rename =
 260                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 261
 262         if (obj_req->rename == 0)
 263                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
 264 }
 265
 266 static void process_object_response(void *callback_data)
 267 {
 268         struct object_request *obj_req =
 269                 (struct object_request *)callback_data;
 270         struct walker *walker = obj_req->walker;
 271         struct walker_data *data = walker->data;
 272         struct alt_base *alt = data->alt;
 273
 274         obj_req->curl_result = obj_req->slot->curl_result;
 275         obj_req->http_code = obj_req->slot->http_code;
 276         obj_req->slot = NULL;
 277         obj_req->state = COMPLETE;
 278
 279         /* Use alternates if necessary */
 280         if (missing_target(obj_req)) {
 281                 fetch_alternates(walker, alt->base);
 282                 if (obj_req->repo->next != NULL) {
 283                         obj_req->repo =
 284                                 obj_req->repo->next;
 285                         close(obj_req->local);
 286                         obj_req->local = -1;
 287                         start_object_request(walker, obj_req);
 288                         return;
 289                 }
 290         }
 291
 292         finish_object_request(obj_req);
 293 }
 294
 295 static void release_object_request(struct object_request *obj_req)
 296 {
 297         struct object_request *entry = object_queue_head;
 298
 299         if (obj_req->local != -1)
 300                 error("fd leakage in release: %d", obj_req->local);
 301         if (obj_req == object_queue_head) {
 302                 object_queue_head = obj_req->next;
 303         } else {
 304                 while (entry->next != NULL && entry->next != obj_req)
 305                         entry = entry->next;
 306                 if (entry->next == obj_req)
 307                         entry->next = entry->next->next;
 308         }
 309
 310         free(obj_req->url);
 311         free(obj_req);
 312 }
 313
 314 #ifdef USE_CURL_MULTI
 315 static int fill_active_slot(struct walker *walker)
 316 {
 317         struct object_request *obj_req;
 318
 319         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
 320                 if (obj_req->state == WAITING) {
 321                         if (has_sha1_file(obj_req->sha1))
 322                                 obj_req->state = COMPLETE;
 323                         else {
 324                                 start_object_request(walker, obj_req);
 325                                 return 1;
 326                         }
 327                 }
 328         }
 329         return 0;
 330 }
 331 #endif
 332
 333 static void prefetch(struct walker *walker, unsigned char *sha1)
 334 {
 335         struct object_request *newreq;
 336         struct object_request *tail;
 337         struct walker_data *data = walker->data;
 338         char *filename = sha1_file_name(sha1);
 339
 340         newreq = xmalloc(sizeof(*newreq));
 341         newreq->walker = walker;
 342         hashcpy(newreq->sha1, sha1);
 343         newreq->repo = data->alt;
 344         newreq->url = NULL;
 345         newreq->local = -1;
 346         newreq->state = WAITING;
 347         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
 348         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
 349                  "%s.temp", filename);
 350         newreq->slot = NULL;
 351         newreq->next = NULL;
 352
 353         http_is_verbose = walker->get_verbosely;
 354
 355         if (object_queue_head == NULL) {
 356                 object_queue_head = newreq;
 357         } else {
 358                 tail = object_queue_head;
 359                 while (tail->next != NULL)
 360                         tail = tail->next;
 361                 tail->next = newreq;
 362         }
 363
 364 #ifdef USE_CURL_MULTI
 365         fill_active_slots();
 366         step_active_slots();
 367 #endif
 368 }
 369
 370 static void process_alternates_response(void *callback_data)
 371 {
 372         struct alternates_request *alt_req =
 373                 (struct alternates_request *)callback_data;
 374         struct walker *walker = alt_req->walker;
 375         struct walker_data *cdata = walker->data;
 376         struct active_request_slot *slot = alt_req->slot;
 377         struct alt_base *tail = cdata->alt;
 378         const char *base = alt_req->base;
 379         static const char null_byte = '\0';
 380         char *data;
 381         int i = 0;
 382
 383         if (alt_req->http_specific) {
 384                 if (slot->curl_result != CURLE_OK ||
 385                     !alt_req->buffer->len) {
 386
 387                         /* Try reusing the slot to get non-http alternates */
 388                         alt_req->http_specific = 0;
 389                         sprintf(alt_req->url, "%s/objects/info/alternates",
 390                                 base);
 391                         curl_easy_setopt(slot->curl, CURLOPT_URL,
 392                                          alt_req->url);
 393                         active_requests++;
 394                         slot->in_use = 1;
 395                         if (slot->finished != NULL)
 396                                 (*slot->finished) = 0;
 397                         if (!start_active_slot(slot)) {
 398                                 cdata->got_alternates = -1;
 399                                 slot->in_use = 0;
 400                                 if (slot->finished != NULL)
 401                                         (*slot->finished) = 1;
 402                         }
 403                         return;
 404                 }
 405         } else if (slot->curl_result != CURLE_OK) {
 406                 if (!missing_target(slot)) {
 407                         cdata->got_alternates = -1;
 408                         return;
 409                 }
 410         }
 411
 412         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 413         alt_req->buffer->len--;
 414         data = alt_req->buffer->buf;
 415
 416         while (i < alt_req->buffer->len) {
 417                 int posn = i;
 418                 while (posn < alt_req->buffer->len && data[posn] != '\n')
 419                         posn++;
 420                 if (data[posn] == '\n') {
 421                         int okay = 0;
 422                         int serverlen = 0;
 423                         struct alt_base *newalt;
 424                         char *target = NULL;
 425                         if (data[i] == '/') {
 426                                 /*
 427                                  * This counts
 428                                  * http://git.host/pub/scm/linux.git/
 429                                  * -----------here^
 430                                  * so memcpy(dst, base, serverlen) will
 431                                  * copy up to "...git.host".
 432                                  */
 433                                 const char *colon_ss = strstr(base,"://");
 434                                 if (colon_ss) {
 435                                         serverlen = (strchr(colon_ss + 3, '/')
 436                                                      - base);
 437                                         okay = 1;
 438                                 }
 439                         } else if (!memcmp(data + i, "../", 3)) {
 440                                 /*
 441                                  * Relative URL; chop the corresponding
 442                                  * number of subpath from base (and ../
 443                                  * from data), and concatenate the result.
 444                                  *
 445                                  * The code first drops ../ from data, and
 446                                  * then drops one ../ from data and one path
 447                                  * from base.  IOW, one extra ../ is dropped
 448                                  * from data than path is dropped from base.
 449                                  *
 450                                  * This is not wrong.  The alternate in
 451                                  *     http://git.host/pub/scm/linux.git/
 452                                  * to borrow from
 453                                  *     http://git.host/pub/scm/linus.git/
 454                                  * is ../../linus.git/objects/.  You need
 455                                  * two ../../ to borrow from your direct
 456                                  * neighbour.
 457                                  */
 458                                 i += 3;
 459                                 serverlen = strlen(base);
 460                                 while (i + 2 < posn &&
 461                                        !memcmp(data + i, "../", 3)) {
 462                                         do {
 463                                                 serverlen--;
 464                                         } while (serverlen &&
 465                                                  base[serverlen - 1] != '/');
 466                                         i += 3;
 467                                 }
 468                                 /* If the server got removed, give up. */
 469                                 okay = strchr(base, ':') - base + 3 <
 470                                        serverlen;
 471                         } else if (alt_req->http_specific) {
 472                                 char *colon = strchr(data + i, ':');
 473                                 char *slash = strchr(data + i, '/');
 474                                 if (colon && slash && colon < data + posn &&
 475                                     slash < data + posn && colon < slash) {
 476                                         okay = 1;
 477                                 }
 478                         }
 479                         /* skip "objects\n" at end */
 480                         if (okay) {
 481                                 target = xmalloc(serverlen + posn - i - 6);
 482                                 memcpy(target, base, serverlen);
 483                                 memcpy(target + serverlen, data + i,
 484                                        posn - i - 7);
 485                                 target[serverlen + posn - i - 7] = 0;
 486                                 if (walker->get_verbosely)
 487                                         fprintf(stderr,
 488                                                 "Also look at %s\n", target);
 489                                 newalt = xmalloc(sizeof(*newalt));
 490                                 newalt->next = NULL;
 491                                 newalt->base = target;
 492                                 newalt->got_indices = 0;
 493                                 newalt->packs = NULL;
 494
 495                                 while (tail->next != NULL)
 496                                         tail = tail->next;
 497                                 tail->next = newalt;
 498                         }
 499                 }
 500                 i = posn + 1;
 501         }
 502
 503         cdata->got_alternates = 1;
 504 }
 505
 506 static void fetch_alternates(struct walker *walker, const char *base)
 507 {
 508         struct strbuf buffer = STRBUF_INIT;
 509         char *url;
 510         struct active_request_slot *slot;
 511         struct alternates_request alt_req;
 512         struct walker_data *cdata = walker->data;
 513
 514         /*
 515          * If another request has already started fetching alternates,
 516          * wait for them to arrive and return to processing this request's
 517          * curl message
 518          */
 519 #ifdef USE_CURL_MULTI
 520         while (cdata->got_alternates == 0) {
 521                 step_active_slots();
 522         }
 523 #endif
 524
 525         /* Nothing to do if they've already been fetched */
 526         if (cdata->got_alternates == 1)
 527                 return;
 528
 529         /* Start the fetch */
 530         cdata->got_alternates = 0;
 531
 532         if (walker->get_verbosely)
 533                 fprintf(stderr, "Getting alternates list for %s\n", base);
 534
 535         url = xmalloc(strlen(base) + 31);
 536         sprintf(url, "%s/objects/info/http-alternates", base);
 537
 538         /*
 539          * Use a callback to process the result, since another request
 540          * may fail and need to have alternates loaded before continuing
 541          */
 542         slot = get_active_slot();
 543         slot->callback_func = process_alternates_response;
 544         alt_req.walker = walker;
 545         slot->callback_data = &alt_req;
 546
 547         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 548         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 549         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 550
 551         alt_req.base = base;
 552         alt_req.url = url;
 553         alt_req.buffer = &buffer;
 554         alt_req.http_specific = 1;
 555         alt_req.slot = slot;
 556
 557         if (start_active_slot(slot))
 558                 run_active_slot(slot);
 559         else
 560                 cdata->got_alternates = -1;
 561
 562         strbuf_release(&buffer);
 563         free(url);
 564 }
 565
 566 static int fetch_indices(struct walker *walker, struct alt_base *repo)
 567 {
 568         int ret;
 569
 570         if (repo->got_indices)
 571                 return 0;
 572
 573         if (walker->get_verbosely)
 574                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
 575
 576         switch (http_get_info_packs(repo->base, &repo->packs)) {
 577         case HTTP_OK:
 578         case HTTP_MISSING_TARGET:
 579                 repo->got_indices = 1;
 580                 ret = 0;
 581                 break;
 582         default:
 583                 repo->got_indices = 0;
 584                 ret = -1;
 585         }
 586
 587         return ret;
 588 }
 589
 590 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 591 {
 592         struct packed_git *target;
 593         int ret;
 594         struct slot_results results;
 595         struct http_pack_request *preq;
 596
 597         if (fetch_indices(walker, repo))
 598                 return -1;
 599         target = find_sha1_pack(sha1, repo->packs);
 600         if (!target)
 601                 return -1;
 602
 603         if (walker->get_verbosely) {
 604                 fprintf(stderr, "Getting pack %s\n",
 605                         sha1_to_hex(target->sha1));
 606                 fprintf(stderr, " which contains %s\n",
 607                         sha1_to_hex(sha1));
 608         }
 609
 610         preq = new_http_pack_request(target, repo->base);
 611         if (preq == NULL)
 612                 goto abort;
 613         preq->lst = &repo->packs;
 614         preq->slot->results = &results;
 615
 616         if (start_active_slot(preq->slot)) {
 617                 run_active_slot(preq->slot);
 618                 if (results.curl_result != CURLE_OK) {
 619                         error("Unable to get pack file %s\n%s", preq->url,
 620                               curl_errorstr);
 621                         goto abort;
 622                 }
 623         } else {
 624                 error("Unable to start request");
 625                 goto abort;
 626         }
 627
 628         ret = finish_http_pack_request(preq);
 629         release_http_pack_request(preq);
 630         if (ret)
 631                 return ret;
 632
 633         return 0;
 634
 635 abort:
 636         return -1;
 637 }
 638
 639 static void abort_object_request(struct object_request *obj_req)
 640 {
 641         if (obj_req->local >= 0) {
 642                 close(obj_req->local);
 643                 obj_req->local = -1;
 644         }
 645         unlink_or_warn(obj_req->tmpfile);
 646         if (obj_req->slot) {
 647                 release_active_slot(obj_req->slot);
 648                 obj_req->slot = NULL;
 649         }
 650         release_object_request(obj_req);
 651 }
 652
 653 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 654 {
 655         char *hex = sha1_to_hex(sha1);
 656         int ret = 0;
 657         struct object_request *obj_req = object_queue_head;
 658
 659         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
 660                 obj_req = obj_req->next;
 661         if (obj_req == NULL)
 662                 return error("Couldn't find request for %s in the queue", hex);
 663
 664         if (has_sha1_file(obj_req->sha1)) {
 665                 abort_object_request(obj_req);
 666                 return 0;
 667         }
 668
 669 #ifdef USE_CURL_MULTI
 670         while (obj_req->state == WAITING)
 671                 step_active_slots();
 672 #else
 673         start_object_request(walker, obj_req);
 674 #endif
 675
 676         while (obj_req->state == ACTIVE)
 677                 run_active_slot(obj_req->slot);
 678
 679         if (obj_req->local != -1) {
 680                 close(obj_req->local);
 681                 obj_req->local = -1;
 682         }
 683
 684         if (obj_req->state == ABORTED) {
 685                 ret = error("Request for %s aborted", hex);
 686         } else if (obj_req->curl_result != CURLE_OK &&
 687                    obj_req->http_code != 416) {
 688                 if (missing_target(obj_req))
 689                         ret = -1; /* Be silent, it is probably in a pack. */
 690                 else
 691                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 692                                     obj_req->errorstr, obj_req->curl_result,
 693                                     obj_req->http_code, hex);
 694         } else if (obj_req->zret != Z_STREAM_END) {
 695                 walker->corrupt_object_found++;
 696                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
 697         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 698                 ret = error("File %s has bad hash", hex);
 699         } else if (obj_req->rename < 0) {
 700                 ret = error("unable to write sha1 filename %s",
 701                             obj_req->filename);
 702         }
 703
 704         release_object_request(obj_req);
 705         return ret;
 706 }
 707
 708 static int fetch(struct walker *walker, unsigned char *sha1)
 709 {
 710         struct walker_data *data = walker->data;
 711         struct alt_base *altbase = data->alt;
 712
 713         if (!fetch_object(walker, altbase, sha1))
 714                 return 0;
 715         while (altbase) {
 716                 if (!fetch_pack(walker, altbase, sha1))
 717                         return 0;
 718                 fetch_alternates(walker, data->alt->base);
 719                 altbase = altbase->next;
 720         }
 721         return error("Unable to find %s under %s", sha1_to_hex(sha1),
 722                      data->alt->base);
 723 }
 724
 725 static int fetch_ref(struct walker *walker, struct ref *ref)
 726 {
 727         struct walker_data *data = walker->data;
 728         return http_fetch_ref(data->alt->base, ref);
 729 }
 730
 731 static void cleanup(struct walker *walker)
 732 {
 733         http_cleanup();
 734 }
 735
 736 struct walker *get_http_walker(const char *url, struct remote *remote)
 737 {
 738         char *s;
 739         struct walker_data *data = xmalloc(sizeof(struct walker_data));
 740         struct walker *walker = xmalloc(sizeof(struct walker));
 741
 742         http_init(remote);
 743
 744         data->alt = xmalloc(sizeof(*data->alt));
 745         data->alt->base = xmalloc(strlen(url) + 1);
 746         strcpy(data->alt->base, url);
 747         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
 748                 *s = 0;
 749
 750         data->alt->got_indices = 0;
 751         data->alt->packs = NULL;
 752         data->alt->next = NULL;
 753         data->got_alternates = -1;
 754
 755         walker->corrupt_object_found = 0;
 756         walker->fetch = fetch;
 757         walker->fetch_ref = fetch_ref;
 758         walker->prefetch = prefetch;
 759         walker->cleanup = cleanup;
 760         walker->data = data;
 761
 762 #ifdef USE_CURL_MULTI
 763         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
 764 #endif
 765
 766         return walker;
 767 }