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         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 = inflate(&obj_req->stream, Z_SYNC_FLUSH);
  86                 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(prevfile);
 115         rename(obj_req->tmpfile, prevfile);
 116         unlink(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         /* This could have failed due to the "lazy directory creation";
 123          * try to mkdir the last path component.
 124          */
 125         if (obj_req->local < 0 && errno == ENOENT) {
 126                 char *dir = strrchr(obj_req->tmpfile, '/');
 127                 if (dir) {
 128                         *dir = 0;
 129                         mkdir(obj_req->tmpfile, 0777);
 130                         *dir = '/';
 131                 }
 132                 obj_req->local = open(obj_req->tmpfile,
 133                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
 134         }
 135
 136         if (obj_req->local < 0) {
 137                 obj_req->state = ABORTED;
 138                 error("Couldn't create temporary file %s for %s: %s",
 139                       obj_req->tmpfile, obj_req->filename, strerror(errno));
 140                 return;
 141         }
 142
 143         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 144
 145         inflateInit(&obj_req->stream);
 146
 147         SHA1_Init(&obj_req->c);
 148
 149         url = xmalloc(strlen(obj_req->repo->base) + 51);
 150         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 51);
 151         strcpy(url, obj_req->repo->base);
 152         posn = url + strlen(obj_req->repo->base);
 153         strcpy(posn, "/objects/");
 154         posn += 9;
 155         memcpy(posn, hex, 2);
 156         posn += 2;
 157         *(posn++) = '/';
 158         strcpy(posn, hex + 2);
 159         strcpy(obj_req->url, url);
 160
 161         /* If a previous temp file is present, process what was already
 162            fetched. */
 163         prevlocal = open(prevfile, O_RDONLY);
 164         if (prevlocal != -1) {
 165                 do {
 166                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
 167                         if (prev_read>0) {
 168                                 if (fwrite_sha1_file(prev_buf,
 169                                                      1,
 170                                                      prev_read,
 171                                                      obj_req) == prev_read) {
 172                                         prev_posn += prev_read;
 173                                 } else {
 174                                         prev_read = -1;
 175                                 }
 176                         }
 177                 } while (prev_read > 0);
 178                 close(prevlocal);
 179         }
 180         unlink(prevfile);
 181
 182         /* Reset inflate/SHA1 if there was an error reading the previous temp
 183            file; also rewind to the beginning of the local file. */
 184         if (prev_read == -1) {
 185                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 186                 inflateInit(&obj_req->stream);
 187                 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, data->no_pragma_header);
 205
 206         /* If we have successfully processed data from a previous fetch
 207            attempt, only fetch the data we don't already have. */
 208         if (prev_posn>0) {
 209                 if (walker->get_verbosely)
 210                         fprintf(stderr,
 211                                 "Resuming fetch of object %s at byte %ld\n",
 212                                 hex, prev_posn);
 213                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 214                 range_header = curl_slist_append(range_header, range);
 215                 curl_easy_setopt(slot->curl,
 216                                  CURLOPT_HTTPHEADER, range_header);
 217         }
 218
 219         /* Try to get the request started, abort the request on error */
 220         obj_req->state = ACTIVE;
 221         if (!start_active_slot(slot)) {
 222                 obj_req->state = ABORTED;
 223                 obj_req->slot = NULL;
 224                 close(obj_req->local); obj_req->local = -1;
 225                 free(obj_req->url);
 226                 return;
 227         }
 228 }
 229
 230 static void finish_object_request(struct object_request *obj_req)
 231 {
 232         struct stat st;
 233
 234         fchmod(obj_req->local, 0444);
 235         close(obj_req->local); obj_req->local = -1;
 236
 237         if (obj_req->http_code == 416) {
 238                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 239         } else if (obj_req->curl_result != CURLE_OK) {
 240                 if (stat(obj_req->tmpfile, &st) == 0)
 241                         if (st.st_size == 0)
 242                                 unlink(obj_req->tmpfile);
 243                 return;
 244         }
 245
 246         inflateEnd(&obj_req->stream);
 247         SHA1_Final(obj_req->real_sha1, &obj_req->c);
 248         if (obj_req->zret != Z_STREAM_END) {
 249                 unlink(obj_req->tmpfile);
 250                 return;
 251         }
 252         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 253                 unlink(obj_req->tmpfile);
 254                 return;
 255         }
 256         obj_req->rename =
 257                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 258
 259         if (obj_req->rename == 0)
 260                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
 261 }
 262
 263 static void process_object_response(void *callback_data)
 264 {
 265         struct object_request *obj_req =
 266                 (struct object_request *)callback_data;
 267         struct walker *walker = obj_req->walker;
 268         struct walker_data *data = walker->data;
 269         struct alt_base *alt = data->alt;
 270
 271         obj_req->curl_result = obj_req->slot->curl_result;
 272         obj_req->http_code = obj_req->slot->http_code;
 273         obj_req->slot = NULL;
 274         obj_req->state = COMPLETE;
 275
 276         /* Use alternates if necessary */
 277         if (missing_target(obj_req)) {
 278                 fetch_alternates(walker, alt->base);
 279                 if (obj_req->repo->next != NULL) {
 280                         obj_req->repo =
 281                                 obj_req->repo->next;
 282                         close(obj_req->local);
 283                         obj_req->local = -1;
 284                         start_object_request(walker, obj_req);
 285                         return;
 286                 }
 287         }
 288
 289         finish_object_request(obj_req);
 290 }
 291
 292 static void release_object_request(struct object_request *obj_req)
 293 {
 294         struct object_request *entry = object_queue_head;
 295
 296         if (obj_req->local != -1)
 297                 error("fd leakage in release: %d", obj_req->local);
 298         if (obj_req == object_queue_head) {
 299                 object_queue_head = obj_req->next;
 300         } else {
 301                 while (entry->next != NULL && entry->next != obj_req)
 302                         entry = entry->next;
 303                 if (entry->next == obj_req)
 304                         entry->next = entry->next->next;
 305         }
 306
 307         free(obj_req->url);
 308         free(obj_req);
 309 }
 310
 311 #ifdef USE_CURL_MULTI
 312 static int fill_active_slot(struct walker *walker)
 313 {
 314         struct object_request *obj_req;
 315
 316         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
 317                 if (obj_req->state == WAITING) {
 318                         if (has_sha1_file(obj_req->sha1))
 319                                 obj_req->state = COMPLETE;
 320                         else {
 321                                 start_object_request(walker, obj_req);
 322                                 return 1;
 323                         }
 324                 }
 325         }
 326         return 0;
 327 }
 328 #endif
 329
 330 static void prefetch(struct walker *walker, unsigned char *sha1)
 331 {
 332         struct object_request *newreq;
 333         struct object_request *tail;
 334         struct walker_data *data = walker->data;
 335         char *filename = sha1_file_name(sha1);
 336
 337         newreq = xmalloc(sizeof(*newreq));
 338         newreq->walker = walker;
 339         hashcpy(newreq->sha1, sha1);
 340         newreq->repo = data->alt;
 341         newreq->url = NULL;
 342         newreq->local = -1;
 343         newreq->state = WAITING;
 344         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
 345         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
 346                  "%s.temp", filename);
 347         newreq->slot = NULL;
 348         newreq->next = NULL;
 349
 350         if (object_queue_head == NULL) {
 351                 object_queue_head = newreq;
 352         } else {
 353                 tail = object_queue_head;
 354                 while (tail->next != NULL) {
 355                         tail = tail->next;
 356                 }
 357                 tail->next = newreq;
 358         }
 359
 360 #ifdef USE_CURL_MULTI
 361         fill_active_slots();
 362         step_active_slots();
 363 #endif
 364 }
 365
 366 static int fetch_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 367 {
 368         char *hex = sha1_to_hex(sha1);
 369         char *filename;
 370         char *url;
 371         char tmpfile[PATH_MAX];
 372         long prev_posn = 0;
 373         char range[RANGE_HEADER_SIZE];
 374         struct curl_slist *range_header = NULL;
 375         struct walker_data *data = walker->data;
 376
 377         FILE *indexfile;
 378         struct active_request_slot *slot;
 379         struct slot_results results;
 380
 381         if (has_pack_index(sha1))
 382                 return 0;
 383
 384         if (walker->get_verbosely)
 385                 fprintf(stderr, "Getting index for pack %s\n", hex);
 386
 387         url = xmalloc(strlen(repo->base) + 64);
 388         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
 389
 390         filename = sha1_pack_index_name(sha1);
 391         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 392         indexfile = fopen(tmpfile, "a");
 393         if (!indexfile)
 394                 return error("Unable to open local file %s for pack index",
 395                              tmpfile);
 396
 397         slot = get_active_slot();
 398         slot->results = &results;
 399         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
 400         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 401         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 402         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 403         slot->local = indexfile;
 404
 405         /* If there is data present from a previous transfer attempt,
 406            resume where it left off */
 407         prev_posn = ftell(indexfile);
 408         if (prev_posn>0) {
 409                 if (walker->get_verbosely)
 410                         fprintf(stderr,
 411                                 "Resuming fetch of index for pack %s at byte %ld\n",
 412                                 hex, prev_posn);
 413                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 414                 range_header = curl_slist_append(range_header, range);
 415                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 416         }
 417
 418         if (start_active_slot(slot)) {
 419                 run_active_slot(slot);
 420                 if (results.curl_result != CURLE_OK) {
 421                         fclose(indexfile);
 422                         return error("Unable to get pack index %s\n%s", url,
 423                                      curl_errorstr);
 424                 }
 425         } else {
 426                 fclose(indexfile);
 427                 return error("Unable to start request");
 428         }
 429
 430         fclose(indexfile);
 431
 432         return move_temp_to_file(tmpfile, filename);
 433 }
 434
 435 static int setup_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 436 {
 437         struct packed_git *new_pack;
 438         if (has_pack_file(sha1))
 439                 return 0; /* don't list this as something we can get */
 440
 441         if (fetch_index(walker, repo, sha1))
 442                 return -1;
 443
 444         new_pack = parse_pack_index(sha1);
 445         new_pack->next = repo->packs;
 446         repo->packs = new_pack;
 447         return 0;
 448 }
 449
 450 static void process_alternates_response(void *callback_data)
 451 {
 452         struct alternates_request *alt_req =
 453                 (struct alternates_request *)callback_data;
 454         struct walker *walker = alt_req->walker;
 455         struct walker_data *cdata = walker->data;
 456         struct active_request_slot *slot = alt_req->slot;
 457         struct alt_base *tail = cdata->alt;
 458         const char *base = alt_req->base;
 459         static const char null_byte = '\0';
 460         char *data;
 461         int i = 0;
 462
 463         if (alt_req->http_specific) {
 464                 if (slot->curl_result != CURLE_OK ||
 465                     !alt_req->buffer->len) {
 466
 467                         /* Try reusing the slot to get non-http alternates */
 468                         alt_req->http_specific = 0;
 469                         sprintf(alt_req->url, "%s/objects/info/alternates",
 470                                 base);
 471                         curl_easy_setopt(slot->curl, CURLOPT_URL,
 472                                          alt_req->url);
 473                         active_requests++;
 474                         slot->in_use = 1;
 475                         if (slot->finished != NULL)
 476                                 (*slot->finished) = 0;
 477                         if (!start_active_slot(slot)) {
 478                                 cdata->got_alternates = -1;
 479                                 slot->in_use = 0;
 480                                 if (slot->finished != NULL)
 481                                         (*slot->finished) = 1;
 482                         }
 483                         return;
 484                 }
 485         } else if (slot->curl_result != CURLE_OK) {
 486                 if (!missing_target(slot)) {
 487                         cdata->got_alternates = -1;
 488                         return;
 489                 }
 490         }
 491
 492         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 493         alt_req->buffer->len--;
 494         data = alt_req->buffer->buf;
 495
 496         while (i < alt_req->buffer->len) {
 497                 int posn = i;
 498                 while (posn < alt_req->buffer->len && data[posn] != '\n')
 499                         posn++;
 500                 if (data[posn] == '\n') {
 501                         int okay = 0;
 502                         int serverlen = 0;
 503                         struct alt_base *newalt;
 504                         char *target = NULL;
 505                         if (data[i] == '/') {
 506                                 /* This counts
 507                                  * http://git.host/pub/scm/linux.git/
 508                                  * -----------here^
 509                                  * so memcpy(dst, base, serverlen) will
 510                                  * copy up to "...git.host".
 511                                  */
 512                                 const char *colon_ss = strstr(base,"://");
 513                                 if (colon_ss) {
 514                                         serverlen = (strchr(colon_ss + 3, '/')
 515                                                      - base);
 516                                         okay = 1;
 517                                 }
 518                         } else if (!memcmp(data + i, "../", 3)) {
 519                                 /* Relative URL; chop the corresponding
 520                                  * number of subpath from base (and ../
 521                                  * from data), and concatenate the result.
 522                                  *
 523                                  * The code first drops ../ from data, and
 524                                  * then drops one ../ from data and one path
 525                                  * from base.  IOW, one extra ../ is dropped
 526                                  * from data than path is dropped from base.
 527                                  *
 528                                  * This is not wrong.  The alternate in
 529                                  *     http://git.host/pub/scm/linux.git/
 530                                  * to borrow from
 531                                  *     http://git.host/pub/scm/linus.git/
 532                                  * is ../../linus.git/objects/.  You need
 533                                  * two ../../ to borrow from your direct
 534                                  * neighbour.
 535                                  */
 536                                 i += 3;
 537                                 serverlen = strlen(base);
 538                                 while (i + 2 < posn &&
 539                                        !memcmp(data + i, "../", 3)) {
 540                                         do {
 541                                                 serverlen--;
 542                                         } while (serverlen &&
 543                                                  base[serverlen - 1] != '/');
 544                                         i += 3;
 545                                 }
 546                                 /* If the server got removed, give up. */
 547                                 okay = strchr(base, ':') - base + 3 <
 548                                         serverlen;
 549                         } else if (alt_req->http_specific) {
 550                                 char *colon = strchr(data + i, ':');
 551                                 char *slash = strchr(data + i, '/');
 552                                 if (colon && slash && colon < data + posn &&
 553                                     slash < data + posn && colon < slash) {
 554                                         okay = 1;
 555                                 }
 556                         }
 557                         /* skip "objects\n" at end */
 558                         if (okay) {
 559                                 target = xmalloc(serverlen + posn - i - 6);
 560                                 memcpy(target, base, serverlen);
 561                                 memcpy(target + serverlen, data + i,
 562                                        posn - i - 7);
 563                                 target[serverlen + posn - i - 7] = 0;
 564                                 if (walker->get_verbosely)
 565                                         fprintf(stderr,
 566                                                 "Also look at %s\n", target);
 567                                 newalt = xmalloc(sizeof(*newalt));
 568                                 newalt->next = NULL;
 569                                 newalt->base = target;
 570                                 newalt->got_indices = 0;
 571                                 newalt->packs = NULL;
 572
 573                                 while (tail->next != NULL)
 574                                         tail = tail->next;
 575                                 tail->next = newalt;
 576                         }
 577                 }
 578                 i = posn + 1;
 579         }
 580
 581         cdata->got_alternates = 1;
 582 }
 583
 584 static void fetch_alternates(struct walker *walker, const char *base)
 585 {
 586         struct strbuf buffer = STRBUF_INIT;
 587         char *url;
 588         struct active_request_slot *slot;
 589         struct alternates_request alt_req;
 590         struct walker_data *cdata = walker->data;
 591
 592         /* If another request has already started fetching alternates,
 593            wait for them to arrive and return to processing this request's
 594            curl message */
 595 #ifdef USE_CURL_MULTI
 596         while (cdata->got_alternates == 0) {
 597                 step_active_slots();
 598         }
 599 #endif
 600
 601         /* Nothing to do if they've already been fetched */
 602         if (cdata->got_alternates == 1)
 603                 return;
 604
 605         /* Start the fetch */
 606         cdata->got_alternates = 0;
 607
 608         if (walker->get_verbosely)
 609                 fprintf(stderr, "Getting alternates list for %s\n", base);
 610
 611         url = xmalloc(strlen(base) + 31);
 612         sprintf(url, "%s/objects/info/http-alternates", base);
 613
 614         /* Use a callback to process the result, since another request
 615            may fail and need to have alternates loaded before continuing */
 616         slot = get_active_slot();
 617         slot->callback_func = process_alternates_response;
 618         alt_req.walker = walker;
 619         slot->callback_data = &alt_req;
 620
 621         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 622         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 623         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 624
 625         alt_req.base = base;
 626         alt_req.url = url;
 627         alt_req.buffer = &buffer;
 628         alt_req.http_specific = 1;
 629         alt_req.slot = slot;
 630
 631         if (start_active_slot(slot))
 632                 run_active_slot(slot);
 633         else
 634                 cdata->got_alternates = -1;
 635
 636         strbuf_release(&buffer);
 637         free(url);
 638 }
 639
 640 static int fetch_indices(struct walker *walker, struct alt_base *repo)
 641 {
 642         unsigned char sha1[20];
 643         char *url;
 644         struct strbuf buffer = STRBUF_INIT;
 645         char *data;
 646         int i = 0;
 647         int ret = 0;
 648
 649         struct active_request_slot *slot;
 650         struct slot_results results;
 651
 652         if (repo->got_indices)
 653                 return 0;
 654
 655         if (walker->get_verbosely)
 656                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
 657
 658         url = xmalloc(strlen(repo->base) + 21);
 659         sprintf(url, "%s/objects/info/packs", repo->base);
 660
 661         slot = get_active_slot();
 662         slot->results = &results;
 663         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 664         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 665         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 666         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 667         if (start_active_slot(slot)) {
 668                 run_active_slot(slot);
 669                 if (results.curl_result != CURLE_OK) {
 670                         if (missing_target(&results)) {
 671                                 repo->got_indices = 1;
 672                                 goto cleanup;
 673                         } else {
 674                                 repo->got_indices = 0;
 675                                 ret = error("%s", curl_errorstr);
 676                                 goto cleanup;
 677                         }
 678                 }
 679         } else {
 680                 repo->got_indices = 0;
 681                 ret = error("Unable to start request");
 682                 goto cleanup;
 683         }
 684
 685         data = buffer.buf;
 686         while (i < buffer.len) {
 687                 switch (data[i]) {
 688                 case 'P':
 689                         i++;
 690                         if (i + 52 <= buffer.len &&
 691                             !prefixcmp(data + i, " pack-") &&
 692                             !prefixcmp(data + i + 46, ".pack\n")) {
 693                                 get_sha1_hex(data + i + 6, sha1);
 694                                 setup_index(walker, repo, sha1);
 695                                 i += 51;
 696                                 break;
 697                         }
 698                 default:
 699                         while (i < buffer.len && data[i] != '\n')
 700                                 i++;
 701                 }
 702                 i++;
 703         }
 704
 705         repo->got_indices = 1;
 706 cleanup:
 707         strbuf_release(&buffer);
 708         free(url);
 709         return ret;
 710 }
 711
 712 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 713 {
 714         char *url;
 715         struct packed_git *target;
 716         struct packed_git **lst;
 717         FILE *packfile;
 718         char *filename;
 719         char tmpfile[PATH_MAX];
 720         int ret;
 721         long prev_posn = 0;
 722         char range[RANGE_HEADER_SIZE];
 723         struct curl_slist *range_header = NULL;
 724         struct walker_data *data = walker->data;
 725
 726         struct active_request_slot *slot;
 727         struct slot_results results;
 728
 729         if (fetch_indices(walker, repo))
 730                 return -1;
 731         target = find_sha1_pack(sha1, repo->packs);
 732         if (!target)
 733                 return -1;
 734
 735         if (walker->get_verbosely) {
 736                 fprintf(stderr, "Getting pack %s\n",
 737                         sha1_to_hex(target->sha1));
 738                 fprintf(stderr, " which contains %s\n",
 739                         sha1_to_hex(sha1));
 740         }
 741
 742         url = xmalloc(strlen(repo->base) + 65);
 743         sprintf(url, "%s/objects/pack/pack-%s.pack",
 744                 repo->base, sha1_to_hex(target->sha1));
 745
 746         filename = sha1_pack_name(target->sha1);
 747         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 748         packfile = fopen(tmpfile, "a");
 749         if (!packfile)
 750                 return error("Unable to open local file %s for pack",
 751                              tmpfile);
 752
 753         slot = get_active_slot();
 754         slot->results = &results;
 755         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
 756         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 757         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 758         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 759         slot->local = packfile;
 760
 761         /* If there is data present from a previous transfer attempt,
 762            resume where it left off */
 763         prev_posn = ftell(packfile);
 764         if (prev_posn>0) {
 765                 if (walker->get_verbosely)
 766                         fprintf(stderr,
 767                                 "Resuming fetch of pack %s at byte %ld\n",
 768                                 sha1_to_hex(target->sha1), prev_posn);
 769                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 770                 range_header = curl_slist_append(range_header, range);
 771                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 772         }
 773
 774         if (start_active_slot(slot)) {
 775                 run_active_slot(slot);
 776                 if (results.curl_result != CURLE_OK) {
 777                         fclose(packfile);
 778                         return error("Unable to get pack file %s\n%s", url,
 779                                      curl_errorstr);
 780                 }
 781         } else {
 782                 fclose(packfile);
 783                 return error("Unable to start request");
 784         }
 785
 786         target->pack_size = ftell(packfile);
 787         fclose(packfile);
 788
 789         ret = move_temp_to_file(tmpfile, filename);
 790         if (ret)
 791                 return ret;
 792
 793         lst = &repo->packs;
 794         while (*lst != target)
 795                 lst = &((*lst)->next);
 796         *lst = (*lst)->next;
 797
 798         if (verify_pack(target, 0))
 799                 return -1;
 800         install_packed_git(target);
 801
 802         return 0;
 803 }
 804
 805 static void abort_object_request(struct object_request *obj_req)
 806 {
 807         if (obj_req->local >= 0) {
 808                 close(obj_req->local);
 809                 obj_req->local = -1;
 810         }
 811         unlink(obj_req->tmpfile);
 812         if (obj_req->slot) {
 813                 release_active_slot(obj_req->slot);
 814                 obj_req->slot = NULL;
 815         }
 816         release_object_request(obj_req);
 817 }
 818
 819 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 820 {
 821         char *hex = sha1_to_hex(sha1);
 822         int ret = 0;
 823         struct object_request *obj_req = object_queue_head;
 824
 825         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
 826                 obj_req = obj_req->next;
 827         if (obj_req == NULL)
 828                 return error("Couldn't find request for %s in the queue", hex);
 829
 830         if (has_sha1_file(obj_req->sha1)) {
 831                 abort_object_request(obj_req);
 832                 return 0;
 833         }
 834
 835 #ifdef USE_CURL_MULTI
 836         while (obj_req->state == WAITING) {
 837                 step_active_slots();
 838         }
 839 #else
 840         start_object_request(walker, obj_req);
 841 #endif
 842
 843         while (obj_req->state == ACTIVE) {
 844                 run_active_slot(obj_req->slot);
 845         }
 846         if (obj_req->local != -1) {
 847                 close(obj_req->local); obj_req->local = -1;
 848         }
 849
 850         if (obj_req->state == ABORTED) {
 851                 ret = error("Request for %s aborted", hex);
 852         } else if (obj_req->curl_result != CURLE_OK &&
 853                    obj_req->http_code != 416) {
 854                 if (missing_target(obj_req))
 855                         ret = -1; /* Be silent, it is probably in a pack. */
 856                 else
 857                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 858                                     obj_req->errorstr, obj_req->curl_result,
 859                                     obj_req->http_code, hex);
 860         } else if (obj_req->zret != Z_STREAM_END) {
 861                 walker->corrupt_object_found++;
 862                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
 863         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 864                 ret = error("File %s has bad hash", hex);
 865         } else if (obj_req->rename < 0) {
 866                 ret = error("unable to write sha1 filename %s",
 867                             obj_req->filename);
 868         }
 869
 870         release_object_request(obj_req);
 871         return ret;
 872 }
 873
 874 static int fetch(struct walker *walker, unsigned char *sha1)
 875 {
 876         struct walker_data *data = walker->data;
 877         struct alt_base *altbase = data->alt;
 878
 879         if (!fetch_object(walker, altbase, sha1))
 880                 return 0;
 881         while (altbase) {
 882                 if (!fetch_pack(walker, altbase, sha1))
 883                         return 0;
 884                 fetch_alternates(walker, data->alt->base);
 885                 altbase = altbase->next;
 886         }
 887         return error("Unable to find %s under %s", sha1_to_hex(sha1),
 888                      data->alt->base);
 889 }
 890
 891 static int fetch_ref(struct walker *walker, char *ref, unsigned char *sha1)
 892 {
 893         struct walker_data *data = walker->data;
 894         return http_fetch_ref(data->alt->base, ref, sha1);
 895 }
 896
 897 static void cleanup(struct walker *walker)
 898 {
 899         struct walker_data *data = walker->data;
 900         http_cleanup();
 901
 902         curl_slist_free_all(data->no_pragma_header);
 903 }
 904
 905 struct walker *get_http_walker(const char *url)
 906 {
 907         char *s;
 908         struct walker_data *data = xmalloc(sizeof(struct walker_data));
 909         struct walker *walker = xmalloc(sizeof(struct walker));
 910
 911         http_init();
 912
 913         data->no_pragma_header = curl_slist_append(NULL, "Pragma:");
 914
 915         data->alt = xmalloc(sizeof(*data->alt));
 916         data->alt->base = xmalloc(strlen(url) + 1);
 917         strcpy(data->alt->base, url);
 918         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
 919                 *s = 0;
 920
 921         data->alt->got_indices = 0;
 922         data->alt->packs = NULL;
 923         data->alt->next = NULL;
 924         data->got_alternates = -1;
 925
 926         walker->corrupt_object_found = 0;
 927         walker->fetch = fetch;
 928         walker->fetch_ref = fetch_ref;
 929         walker->prefetch = prefetch;
 930         walker->cleanup = cleanup;
 931         walker->data = data;
 932
 933 #ifdef USE_CURL_MULTI
 934         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
 935 #endif
 936
 937         return walker;
 938 }