http-walker.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "pack.h"
   4 #include "walker.h"
   5 #include "http.h"
   6
   7 #define PREV_BUF_SIZE 4096
   8 #define RANGE_HEADER_SIZE 30
   9
  10 struct alt_base
  11 {
  12         char *base;
  13         int got_indices;
  14         struct packed_git *packs;
  15         struct alt_base *next;
  16 };
  17
  18 enum object_request_state {
  19         WAITING,
  20         ABORTED,
  21         ACTIVE,
  22         COMPLETE,
  23 };
  24
  25 struct object_request
  26 {
  27         struct walker *walker;
  28         unsigned char sha1[20];
  29         struct alt_base *repo;
  30         char *url;
  31         char filename[PATH_MAX];
  32         char tmpfile[PATH_MAX];
  33         int local;
  34         enum object_request_state state;
  35         CURLcode curl_result;
  36         char errorstr[CURL_ERROR_SIZE];
  37         long http_code;
  38         unsigned char real_sha1[20];
  39         git_SHA_CTX c;
  40         z_stream stream;
  41         int zret;
  42         int rename;
  43         struct active_request_slot *slot;
  44         struct object_request *next;
  45 };
  46
  47 struct alternates_request {
  48         struct walker *walker;
  49         const char *base;
  50         char *url;
  51         struct strbuf *buffer;
  52         struct active_request_slot *slot;
  53         int http_specific;
  54 };
  55
  56 struct walker_data {
  57         const char *url;
  58         int got_alternates;
  59         struct alt_base *alt;
  60         struct curl_slist *no_pragma_header;
  61 };
  62
  63 static struct object_request *object_queue_head;
  64
  65 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
  66                                void *data)
  67 {
  68         unsigned char expn[4096];
  69         size_t size = eltsize * nmemb;
  70         int posn = 0;
  71         struct object_request *obj_req = (struct object_request *)data;
  72         do {
  73                 ssize_t retval = xwrite(obj_req->local,
  74                                         (char *) ptr + posn, size - posn);
  75                 if (retval < 0)
  76                         return posn;
  77                 posn += retval;
  78         } while (posn < size);
  79
  80         obj_req->stream.avail_in = size;
  81         obj_req->stream.next_in = ptr;
  82         do {
  83                 obj_req->stream.next_out = expn;
  84                 obj_req->stream.avail_out = sizeof(expn);
  85                 obj_req->zret = git_inflate(&obj_req->stream, Z_SYNC_FLUSH);
  86                 git_SHA1_Update(&obj_req->c, expn,
  87                                 sizeof(expn) - obj_req->stream.avail_out);
  88         } while (obj_req->stream.avail_in && obj_req->zret == Z_OK);
  89         data_received++;
  90         return size;
  91 }
  92
  93 static void fetch_alternates(struct walker *walker, const char *base);
  94
  95 static void process_object_response(void *callback_data);
  96
  97 static void start_object_request(struct walker *walker,
  98                                  struct object_request *obj_req)
  99 {
 100         char *hex = sha1_to_hex(obj_req->sha1);
 101         char prevfile[PATH_MAX];
 102         char *url;
 103         char *posn;
 104         int prevlocal;
 105         unsigned char prev_buf[PREV_BUF_SIZE];
 106         ssize_t prev_read = 0;
 107         long prev_posn = 0;
 108         char range[RANGE_HEADER_SIZE];
 109         struct curl_slist *range_header = NULL;
 110         struct active_request_slot *slot;
 111         struct walker_data *data = walker->data;
 112
 113         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
 114         unlink_or_warn(prevfile);
 115         rename(obj_req->tmpfile, prevfile);
 116         unlink_or_warn(obj_req->tmpfile);
 117
 118         if (obj_req->local != -1)
 119                 error("fd leakage in start: %d", obj_req->local);
 120         obj_req->local = open(obj_req->tmpfile,
 121                               O_WRONLY | O_CREAT | O_EXCL, 0666);
 122         /*
 123          * This could have failed due to the "lazy directory creation";
 124          * try to mkdir the last path component.
 125          */
 126         if (obj_req->local < 0 && errno == ENOENT) {
 127                 char *dir = strrchr(obj_req->tmpfile, '/');
 128                 if (dir) {
 129                         *dir = 0;
 130                         mkdir(obj_req->tmpfile, 0777);
 131                         *dir = '/';
 132                 }
 133                 obj_req->local = open(obj_req->tmpfile,
 134                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
 135         }
 136
 137         if (obj_req->local < 0) {
 138                 obj_req->state = ABORTED;
 139                 error("Couldn't create temporary file %s for %s: %s",
 140                       obj_req->tmpfile, obj_req->filename, strerror(errno));
 141                 return;
 142         }
 143
 144         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 145
 146         git_inflate_init(&obj_req->stream);
 147
 148         git_SHA1_Init(&obj_req->c);
 149
 150         url = xmalloc(strlen(obj_req->repo->base) + 51);
 151         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 51);
 152         strcpy(url, obj_req->repo->base);
 153         posn = url + strlen(obj_req->repo->base);
 154         strcpy(posn, "/objects/");
 155         posn += 9;
 156         memcpy(posn, hex, 2);
 157         posn += 2;
 158         *(posn++) = '/';
 159         strcpy(posn, hex + 2);
 160         strcpy(obj_req->url, url);
 161
 162         /*
 163          * If a previous temp file is present, process what was already
 164          * fetched.
 165          */
 166         prevlocal = open(prevfile, O_RDONLY);
 167         if (prevlocal != -1) {
 168                 do {
 169                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
 170                         if (prev_read>0) {
 171                                 if (fwrite_sha1_file(prev_buf,
 172                                                      1,
 173                                                      prev_read,
 174                                                      obj_req) == prev_read)
 175                                         prev_posn += prev_read;
 176                                 else
 177                                         prev_read = -1;
 178                         }
 179                 } while (prev_read > 0);
 180                 close(prevlocal);
 181         }
 182         unlink_or_warn(prevfile);
 183
 184         /*
 185          * Reset inflate/SHA1 if there was an error reading the previous temp
 186          * file; also rewind to the beginning of the local file.
 187          */
 188         if (prev_read == -1) {
 189                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 190                 git_inflate_init(&obj_req->stream);
 191                 git_SHA1_Init(&obj_req->c);
 192                 if (prev_posn>0) {
 193                         prev_posn = 0;
 194                         lseek(obj_req->local, 0, SEEK_SET);
 195                         ftruncate(obj_req->local, 0);
 196                 }
 197         }
 198
 199         slot = get_active_slot();
 200         slot->callback_func = process_object_response;
 201         slot->callback_data = obj_req;
 202         obj_req->slot = slot;
 203
 204         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
 205         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
 206         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
 207         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 208         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 209
 210         /*
 211          * If we have successfully processed data from a previous fetch
 212          * attempt, only fetch the data we don't already have.
 213          */
 214         if (prev_posn>0) {
 215                 if (walker->get_verbosely)
 216                         fprintf(stderr,
 217                                 "Resuming fetch of object %s at byte %ld\n",
 218                                 hex, prev_posn);
 219                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 220                 range_header = curl_slist_append(range_header, range);
 221                 curl_easy_setopt(slot->curl,
 222                                  CURLOPT_HTTPHEADER, range_header);
 223         }
 224
 225         /* Try to get the request started, abort the request on error */
 226         obj_req->state = ACTIVE;
 227         if (!start_active_slot(slot)) {
 228                 obj_req->state = ABORTED;
 229                 obj_req->slot = NULL;
 230                 close(obj_req->local);
 231                 obj_req->local = -1;
 232                 free(obj_req->url);
 233                 return;
 234         }
 235 }
 236
 237 static void finish_object_request(struct object_request *obj_req)
 238 {
 239         struct stat st;
 240
 241         close(obj_req->local);
 242         obj_req->local = -1;
 243
 244         if (obj_req->http_code == 416) {
 245                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 246         } else if (obj_req->curl_result != CURLE_OK) {
 247                 if (stat(obj_req->tmpfile, &st) == 0)
 248                         if (st.st_size == 0)
 249                                 unlink_or_warn(obj_req->tmpfile);
 250                 return;
 251         }
 252
 253         git_inflate_end(&obj_req->stream);
 254         git_SHA1_Final(obj_req->real_sha1, &obj_req->c);
 255         if (obj_req->zret != Z_STREAM_END) {
 256                 unlink_or_warn(obj_req->tmpfile);
 257                 return;
 258         }
 259         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 260                 unlink_or_warn(obj_req->tmpfile);
 261                 return;
 262         }
 263         obj_req->rename =
 264                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 265
 266         if (obj_req->rename == 0)
 267                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
 268 }
 269
 270 static void process_object_response(void *callback_data)
 271 {
 272         struct object_request *obj_req =
 273                 (struct object_request *)callback_data;
 274         struct walker *walker = obj_req->walker;
 275         struct walker_data *data = walker->data;
 276         struct alt_base *alt = data->alt;
 277
 278         obj_req->curl_result = obj_req->slot->curl_result;
 279         obj_req->http_code = obj_req->slot->http_code;
 280         obj_req->slot = NULL;
 281         obj_req->state = COMPLETE;
 282
 283         /* Use alternates if necessary */
 284         if (missing_target(obj_req)) {
 285                 fetch_alternates(walker, alt->base);
 286                 if (obj_req->repo->next != NULL) {
 287                         obj_req->repo =
 288                                 obj_req->repo->next;
 289                         close(obj_req->local);
 290                         obj_req->local = -1;
 291                         start_object_request(walker, obj_req);
 292                         return;
 293                 }
 294         }
 295
 296         finish_object_request(obj_req);
 297 }
 298
 299 static void release_object_request(struct object_request *obj_req)
 300 {
 301         struct object_request *entry = object_queue_head;
 302
 303         if (obj_req->local != -1)
 304                 error("fd leakage in release: %d", obj_req->local);
 305         if (obj_req == object_queue_head) {
 306                 object_queue_head = obj_req->next;
 307         } else {
 308                 while (entry->next != NULL && entry->next != obj_req)
 309                         entry = entry->next;
 310                 if (entry->next == obj_req)
 311                         entry->next = entry->next->next;
 312         }
 313
 314         free(obj_req->url);
 315         free(obj_req);
 316 }
 317
 318 #ifdef USE_CURL_MULTI
 319 static int fill_active_slot(struct walker *walker)
 320 {
 321         struct object_request *obj_req;
 322
 323         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
 324                 if (obj_req->state == WAITING) {
 325                         if (has_sha1_file(obj_req->sha1))
 326                                 obj_req->state = COMPLETE;
 327                         else {
 328                                 start_object_request(walker, obj_req);
 329                                 return 1;
 330                         }
 331                 }
 332         }
 333         return 0;
 334 }
 335 #endif
 336
 337 static void prefetch(struct walker *walker, unsigned char *sha1)
 338 {
 339         struct object_request *newreq;
 340         struct object_request *tail;
 341         struct walker_data *data = walker->data;
 342         char *filename = sha1_file_name(sha1);
 343
 344         newreq = xmalloc(sizeof(*newreq));
 345         newreq->walker = walker;
 346         hashcpy(newreq->sha1, sha1);
 347         newreq->repo = data->alt;
 348         newreq->url = NULL;
 349         newreq->local = -1;
 350         newreq->state = WAITING;
 351         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
 352         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
 353                  "%s.temp", filename);
 354         newreq->slot = NULL;
 355         newreq->next = NULL;
 356
 357         if (object_queue_head == NULL) {
 358                 object_queue_head = newreq;
 359         } else {
 360                 tail = object_queue_head;
 361                 while (tail->next != NULL)
 362                         tail = tail->next;
 363                 tail->next = newreq;
 364         }
 365
 366 #ifdef USE_CURL_MULTI
 367         fill_active_slots();
 368         step_active_slots();
 369 #endif
 370 }
 371
 372 static int fetch_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 373 {
 374         int ret = 0;
 375         char *hex = xstrdup(sha1_to_hex(sha1));
 376         char *filename;
 377         char *url;
 378         char tmpfile[PATH_MAX];
 379         long prev_posn = 0;
 380         char range[RANGE_HEADER_SIZE];
 381         struct curl_slist *range_header = NULL;
 382         struct walker_data *data = walker->data;
 383
 384         FILE *indexfile;
 385         struct active_request_slot *slot;
 386         struct slot_results results;
 387
 388         /* Don't use the index if the pack isn't there */
 389         url = xmalloc(strlen(repo->base) + 64);
 390         sprintf(url, "%s/objects/pack/pack-%s.pack", repo->base, hex);
 391         slot = get_active_slot();
 392         slot->results = &results;
 393         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 394         curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 1);
 395         if (start_active_slot(slot)) {
 396                 run_active_slot(slot);
 397                 if (results.curl_result != CURLE_OK) {
 398                         ret = error("Unable to verify pack %s is available",
 399                                      hex);
 400                         goto cleanup_pack;
 401                 }
 402         } else {
 403                 ret = error("Unable to start request");
 404                 goto cleanup_pack;
 405         }
 406
 407         if (has_pack_index(sha1)) {
 408                 ret = 0;
 409                 goto cleanup_pack;
 410         }
 411
 412         if (walker->get_verbosely)
 413                 fprintf(stderr, "Getting index for pack %s\n", hex);
 414
 415         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
 416
 417         filename = sha1_pack_index_name(sha1);
 418         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 419         indexfile = fopen(tmpfile, "a");
 420         if (!indexfile) {
 421                 ret = error("Unable to open local file %s for pack index",
 422                             tmpfile);
 423                 goto cleanup_pack;
 424         }
 425
 426         slot = get_active_slot();
 427         slot->results = &results;
 428         curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
 429         curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
 430         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
 431         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 432         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 433         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 434         slot->local = indexfile;
 435
 436         /*
 437          * If there is data present from a previous transfer attempt,
 438          * resume where it left off
 439          */
 440         prev_posn = ftell(indexfile);
 441         if (prev_posn>0) {
 442                 if (walker->get_verbosely)
 443                         fprintf(stderr,
 444                                 "Resuming fetch of index for pack %s at byte %ld\n",
 445                                 hex, prev_posn);
 446                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 447                 range_header = curl_slist_append(range_header, range);
 448                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 449         }
 450
 451         if (start_active_slot(slot)) {
 452                 run_active_slot(slot);
 453                 if (results.curl_result != CURLE_OK) {
 454                         ret = error("Unable to get pack index %s\n%s", url,
 455                                     curl_errorstr);
 456                         goto cleanup_index;
 457                 }
 458         } else {
 459                 ret = error("Unable to start request");
 460                 goto cleanup_index;
 461         }
 462
 463         ret = move_temp_to_file(tmpfile, filename);
 464
 465 cleanup_index:
 466         fclose(indexfile);
 467         slot->local = NULL;
 468 cleanup_pack:
 469         free(url);
 470         free(hex);
 471         return ret;
 472 }
 473
 474 static int setup_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 475 {
 476         struct packed_git *new_pack;
 477         if (has_pack_file(sha1))
 478                 return 0; /* don't list this as something we can get */
 479
 480         if (fetch_index(walker, repo, sha1))
 481                 return -1;
 482
 483         new_pack = parse_pack_index(sha1);
 484         if (!new_pack)
 485                 return -1; /* parse_pack_index() already issued error message */
 486         new_pack->next = repo->packs;
 487         repo->packs = new_pack;
 488         return 0;
 489 }
 490
 491 static void process_alternates_response(void *callback_data)
 492 {
 493         struct alternates_request *alt_req =
 494                 (struct alternates_request *)callback_data;
 495         struct walker *walker = alt_req->walker;
 496         struct walker_data *cdata = walker->data;
 497         struct active_request_slot *slot = alt_req->slot;
 498         struct alt_base *tail = cdata->alt;
 499         const char *base = alt_req->base;
 500         static const char null_byte = '\0';
 501         char *data;
 502         int i = 0;
 503
 504         if (alt_req->http_specific) {
 505                 if (slot->curl_result != CURLE_OK ||
 506                     !alt_req->buffer->len) {
 507
 508                         /* Try reusing the slot to get non-http alternates */
 509                         alt_req->http_specific = 0;
 510                         sprintf(alt_req->url, "%s/objects/info/alternates",
 511                                 base);
 512                         curl_easy_setopt(slot->curl, CURLOPT_URL,
 513                                          alt_req->url);
 514                         active_requests++;
 515                         slot->in_use = 1;
 516                         if (slot->finished != NULL)
 517                                 (*slot->finished) = 0;
 518                         if (!start_active_slot(slot)) {
 519                                 cdata->got_alternates = -1;
 520                                 slot->in_use = 0;
 521                                 if (slot->finished != NULL)
 522                                         (*slot->finished) = 1;
 523                         }
 524                         return;
 525                 }
 526         } else if (slot->curl_result != CURLE_OK) {
 527                 if (!missing_target(slot)) {
 528                         cdata->got_alternates = -1;
 529                         return;
 530                 }
 531         }
 532
 533         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 534         alt_req->buffer->len--;
 535         data = alt_req->buffer->buf;
 536
 537         while (i < alt_req->buffer->len) {
 538                 int posn = i;
 539                 while (posn < alt_req->buffer->len && data[posn] != '\n')
 540                         posn++;
 541                 if (data[posn] == '\n') {
 542                         int okay = 0;
 543                         int serverlen = 0;
 544                         struct alt_base *newalt;
 545                         char *target = NULL;
 546                         if (data[i] == '/') {
 547                                 /*
 548                                  * This counts
 549                                  * http://git.host/pub/scm/linux.git/
 550                                  * -----------here^
 551                                  * so memcpy(dst, base, serverlen) will
 552                                  * copy up to "...git.host".
 553                                  */
 554                                 const char *colon_ss = strstr(base,"://");
 555                                 if (colon_ss) {
 556                                         serverlen = (strchr(colon_ss + 3, '/')
 557                                                      - base);
 558                                         okay = 1;
 559                                 }
 560                         } else if (!memcmp(data + i, "../", 3)) {
 561                                 /*
 562                                  * Relative URL; chop the corresponding
 563                                  * number of subpath from base (and ../
 564                                  * from data), and concatenate the result.
 565                                  *
 566                                  * The code first drops ../ from data, and
 567                                  * then drops one ../ from data and one path
 568                                  * from base.  IOW, one extra ../ is dropped
 569                                  * from data than path is dropped from base.
 570                                  *
 571                                  * This is not wrong.  The alternate in
 572                                  *     http://git.host/pub/scm/linux.git/
 573                                  * to borrow from
 574                                  *     http://git.host/pub/scm/linus.git/
 575                                  * is ../../linus.git/objects/.  You need
 576                                  * two ../../ to borrow from your direct
 577                                  * neighbour.
 578                                  */
 579                                 i += 3;
 580                                 serverlen = strlen(base);
 581                                 while (i + 2 < posn &&
 582                                        !memcmp(data + i, "../", 3)) {
 583                                         do {
 584                                                 serverlen--;
 585                                         } while (serverlen &&
 586                                                  base[serverlen - 1] != '/');
 587                                         i += 3;
 588                                 }
 589                                 /* If the server got removed, give up. */
 590                                 okay = strchr(base, ':') - base + 3 <
 591                                        serverlen;
 592                         } else if (alt_req->http_specific) {
 593                                 char *colon = strchr(data + i, ':');
 594                                 char *slash = strchr(data + i, '/');
 595                                 if (colon && slash && colon < data + posn &&
 596                                     slash < data + posn && colon < slash) {
 597                                         okay = 1;
 598                                 }
 599                         }
 600                         /* skip "objects\n" at end */
 601                         if (okay) {
 602                                 target = xmalloc(serverlen + posn - i - 6);
 603                                 memcpy(target, base, serverlen);
 604                                 memcpy(target + serverlen, data + i,
 605                                        posn - i - 7);
 606                                 target[serverlen + posn - i - 7] = 0;
 607                                 if (walker->get_verbosely)
 608                                         fprintf(stderr,
 609                                                 "Also look at %s\n", target);
 610                                 newalt = xmalloc(sizeof(*newalt));
 611                                 newalt->next = NULL;
 612                                 newalt->base = target;
 613                                 newalt->got_indices = 0;
 614                                 newalt->packs = NULL;
 615
 616                                 while (tail->next != NULL)
 617                                         tail = tail->next;
 618                                 tail->next = newalt;
 619                         }
 620                 }
 621                 i = posn + 1;
 622         }
 623
 624         cdata->got_alternates = 1;
 625 }
 626
 627 static void fetch_alternates(struct walker *walker, const char *base)
 628 {
 629         struct strbuf buffer = STRBUF_INIT;
 630         char *url;
 631         struct active_request_slot *slot;
 632         struct alternates_request alt_req;
 633         struct walker_data *cdata = walker->data;
 634
 635         /*
 636          * If another request has already started fetching alternates,
 637          * wait for them to arrive and return to processing this request's
 638          * curl message
 639          */
 640 #ifdef USE_CURL_MULTI
 641         while (cdata->got_alternates == 0) {
 642                 step_active_slots();
 643         }
 644 #endif
 645
 646         /* Nothing to do if they've already been fetched */
 647         if (cdata->got_alternates == 1)
 648                 return;
 649
 650         /* Start the fetch */
 651         cdata->got_alternates = 0;
 652
 653         if (walker->get_verbosely)
 654                 fprintf(stderr, "Getting alternates list for %s\n", base);
 655
 656         url = xmalloc(strlen(base) + 31);
 657         sprintf(url, "%s/objects/info/http-alternates", base);
 658
 659         /*
 660          * Use a callback to process the result, since another request
 661          * may fail and need to have alternates loaded before continuing
 662          */
 663         slot = get_active_slot();
 664         slot->callback_func = process_alternates_response;
 665         alt_req.walker = walker;
 666         slot->callback_data = &alt_req;
 667
 668         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 669         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 670         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 671
 672         alt_req.base = base;
 673         alt_req.url = url;
 674         alt_req.buffer = &buffer;
 675         alt_req.http_specific = 1;
 676         alt_req.slot = slot;
 677
 678         if (start_active_slot(slot))
 679                 run_active_slot(slot);
 680         else
 681                 cdata->got_alternates = -1;
 682
 683         strbuf_release(&buffer);
 684         free(url);
 685 }
 686
 687 static int fetch_indices(struct walker *walker, struct alt_base *repo)
 688 {
 689         unsigned char sha1[20];
 690         char *url;
 691         struct strbuf buffer = STRBUF_INIT;
 692         char *data;
 693         int i = 0;
 694         int ret = 0;
 695
 696         struct active_request_slot *slot;
 697         struct slot_results results;
 698
 699         if (repo->got_indices)
 700                 return 0;
 701
 702         if (walker->get_verbosely)
 703                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
 704
 705         url = xmalloc(strlen(repo->base) + 21);
 706         sprintf(url, "%s/objects/info/packs", repo->base);
 707
 708         slot = get_active_slot();
 709         slot->results = &results;
 710         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 711         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 712         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 713         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 714         if (start_active_slot(slot)) {
 715                 run_active_slot(slot);
 716                 if (results.curl_result != CURLE_OK) {
 717                         if (missing_target(&results)) {
 718                                 repo->got_indices = 1;
 719                                 goto cleanup;
 720                         } else {
 721                                 repo->got_indices = 0;
 722                                 ret = error("%s", curl_errorstr);
 723                                 goto cleanup;
 724                         }
 725                 }
 726         } else {
 727                 repo->got_indices = 0;
 728                 ret = error("Unable to start request");
 729                 goto cleanup;
 730         }
 731
 732         data = buffer.buf;
 733         while (i < buffer.len) {
 734                 switch (data[i]) {
 735                 case 'P':
 736                         i++;
 737                         if (i + 52 <= buffer.len &&
 738                             !prefixcmp(data + i, " pack-") &&
 739                             !prefixcmp(data + i + 46, ".pack\n")) {
 740                                 get_sha1_hex(data + i + 6, sha1);
 741                                 setup_index(walker, repo, sha1);
 742                                 i += 51;
 743                                 break;
 744                         }
 745                 default:
 746                         while (i < buffer.len && data[i] != '\n')
 747                                 i++;
 748                 }
 749                 i++;
 750         }
 751
 752         repo->got_indices = 1;
 753 cleanup:
 754         strbuf_release(&buffer);
 755         free(url);
 756         return ret;
 757 }
 758
 759 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 760 {
 761         char *url;
 762         struct packed_git *target;
 763         struct packed_git **lst;
 764         FILE *packfile;
 765         char *filename;
 766         char tmpfile[PATH_MAX];
 767         int ret;
 768         long prev_posn = 0;
 769         char range[RANGE_HEADER_SIZE];
 770         struct curl_slist *range_header = NULL;
 771         struct walker_data *data = walker->data;
 772
 773         struct active_request_slot *slot;
 774         struct slot_results results;
 775
 776         if (fetch_indices(walker, repo))
 777                 return -1;
 778         target = find_sha1_pack(sha1, repo->packs);
 779         if (!target)
 780                 return -1;
 781
 782         if (walker->get_verbosely) {
 783                 fprintf(stderr, "Getting pack %s\n",
 784                         sha1_to_hex(target->sha1));
 785                 fprintf(stderr, " which contains %s\n",
 786                         sha1_to_hex(sha1));
 787         }
 788
 789         url = xmalloc(strlen(repo->base) + 65);
 790         sprintf(url, "%s/objects/pack/pack-%s.pack",
 791                 repo->base, sha1_to_hex(target->sha1));
 792
 793         filename = sha1_pack_name(target->sha1);
 794         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 795         packfile = fopen(tmpfile, "a");
 796         if (!packfile)
 797                 return error("Unable to open local file %s for pack",
 798                              tmpfile);
 799
 800         slot = get_active_slot();
 801         slot->results = &results;
 802         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
 803         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 804         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 805         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 806         slot->local = packfile;
 807
 808         /*
 809          * If there is data present from a previous transfer attempt,
 810          * resume where it left off
 811          */
 812         prev_posn = ftell(packfile);
 813         if (prev_posn>0) {
 814                 if (walker->get_verbosely)
 815                         fprintf(stderr,
 816                                 "Resuming fetch of pack %s at byte %ld\n",
 817                                 sha1_to_hex(target->sha1), prev_posn);
 818                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 819                 range_header = curl_slist_append(range_header, range);
 820                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 821         }
 822
 823         if (start_active_slot(slot)) {
 824                 run_active_slot(slot);
 825                 if (results.curl_result != CURLE_OK) {
 826                         fclose(packfile);
 827                         slot->local = NULL;
 828                         return error("Unable to get pack file %s\n%s", url,
 829                                      curl_errorstr);
 830                 }
 831         } else {
 832                 fclose(packfile);
 833                 slot->local = NULL;
 834                 return error("Unable to start request");
 835         }
 836
 837         target->pack_size = ftell(packfile);
 838         fclose(packfile);
 839         slot->local = NULL;
 840
 841         ret = move_temp_to_file(tmpfile, filename);
 842         if (ret)
 843                 return ret;
 844
 845         lst = &repo->packs;
 846         while (*lst != target)
 847                 lst = &((*lst)->next);
 848         *lst = (*lst)->next;
 849
 850         if (verify_pack(target))
 851                 return -1;
 852         install_packed_git(target);
 853
 854         return 0;
 855 }
 856
 857 static void abort_object_request(struct object_request *obj_req)
 858 {
 859         if (obj_req->local >= 0) {
 860                 close(obj_req->local);
 861                 obj_req->local = -1;
 862         }
 863         unlink_or_warn(obj_req->tmpfile);
 864         if (obj_req->slot) {
 865                 release_active_slot(obj_req->slot);
 866                 obj_req->slot = NULL;
 867         }
 868         release_object_request(obj_req);
 869 }
 870
 871 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 872 {
 873         char *hex = sha1_to_hex(sha1);
 874         int ret = 0;
 875         struct object_request *obj_req = object_queue_head;
 876
 877         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
 878                 obj_req = obj_req->next;
 879         if (obj_req == NULL)
 880                 return error("Couldn't find request for %s in the queue", hex);
 881
 882         if (has_sha1_file(obj_req->sha1)) {
 883                 abort_object_request(obj_req);
 884                 return 0;
 885         }
 886
 887 #ifdef USE_CURL_MULTI
 888         while (obj_req->state == WAITING)
 889                 step_active_slots();
 890 #else
 891         start_object_request(walker, obj_req);
 892 #endif
 893
 894         while (obj_req->state == ACTIVE)
 895                 run_active_slot(obj_req->slot);
 896
 897         if (obj_req->local != -1) {
 898                 close(obj_req->local);
 899                 obj_req->local = -1;
 900         }
 901
 902         if (obj_req->state == ABORTED) {
 903                 ret = error("Request for %s aborted", hex);
 904         } else if (obj_req->curl_result != CURLE_OK &&
 905                    obj_req->http_code != 416) {
 906                 if (missing_target(obj_req))
 907                         ret = -1; /* Be silent, it is probably in a pack. */
 908                 else
 909                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 910                                     obj_req->errorstr, obj_req->curl_result,
 911                                     obj_req->http_code, hex);
 912         } else if (obj_req->zret != Z_STREAM_END) {
 913                 walker->corrupt_object_found++;
 914                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
 915         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 916                 ret = error("File %s has bad hash", hex);
 917         } else if (obj_req->rename < 0) {
 918                 ret = error("unable to write sha1 filename %s",
 919                             obj_req->filename);
 920         }
 921
 922         release_object_request(obj_req);
 923         return ret;
 924 }
 925
 926 static int fetch(struct walker *walker, unsigned char *sha1)
 927 {
 928         struct walker_data *data = walker->data;
 929         struct alt_base *altbase = data->alt;
 930
 931         if (!fetch_object(walker, altbase, sha1))
 932                 return 0;
 933         while (altbase) {
 934                 if (!fetch_pack(walker, altbase, sha1))
 935                         return 0;
 936                 fetch_alternates(walker, data->alt->base);
 937                 altbase = altbase->next;
 938         }
 939         return error("Unable to find %s under %s", sha1_to_hex(sha1),
 940                      data->alt->base);
 941 }
 942
 943 static int fetch_ref(struct walker *walker, struct ref *ref)
 944 {
 945         struct walker_data *data = walker->data;
 946         return http_fetch_ref(data->alt->base, ref);
 947 }
 948
 949 static void cleanup(struct walker *walker)
 950 {
 951         struct walker_data *data = walker->data;
 952         http_cleanup();
 953
 954         curl_slist_free_all(data->no_pragma_header);
 955 }
 956
 957 struct walker *get_http_walker(const char *url, struct remote *remote)
 958 {
 959         char *s;
 960         struct walker_data *data = xmalloc(sizeof(struct walker_data));
 961         struct walker *walker = xmalloc(sizeof(struct walker));
 962
 963         http_init(remote);
 964
 965         data->no_pragma_header = curl_slist_append(NULL, "Pragma:");
 966
 967         data->alt = xmalloc(sizeof(*data->alt));
 968         data->alt->base = xmalloc(strlen(url) + 1);
 969         strcpy(data->alt->base, url);
 970         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
 971                 *s = 0;
 972
 973         data->alt->got_indices = 0;
 974         data->alt->packs = NULL;
 975         data->alt->next = NULL;
 976         data->got_alternates = -1;
 977
 978         walker->corrupt_object_found = 0;
 979         walker->fetch = fetch;
 980         walker->fetch_ref = fetch_ref;
 981         walker->prefetch = prefetch;
 982         walker->cleanup = cleanup;
 983         walker->data = data;
 984
 985 #ifdef USE_CURL_MULTI
 986         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
 987 #endif
 988
 989         return walker;
 990 }