http-fetch.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "pack.h"
   4 #include "fetch.h"
   5 #include "http.h"
   6
   7 #define PREV_BUF_SIZE 4096
   8 #define RANGE_HEADER_SIZE 30
   9
  10 static int got_alternates = -1;
  11
  12 static struct curl_slist *no_pragma_header;
  13
  14 struct alt_base
  15 {
  16         char *base;
  17         int got_indices;
  18         struct packed_git *packs;
  19         struct alt_base *next;
  20 };
  21
  22 static struct alt_base *alt = NULL;
  23
  24 enum object_request_state {
  25         WAITING,
  26         ABORTED,
  27         ACTIVE,
  28         COMPLETE,
  29 };
  30
  31 struct object_request
  32 {
  33         unsigned char sha1[20];
  34         struct alt_base *repo;
  35         char *url;
  36         char filename[PATH_MAX];
  37         char tmpfile[PATH_MAX];
  38         int local;
  39         enum object_request_state state;
  40         CURLcode curl_result;
  41         char errorstr[CURL_ERROR_SIZE];
  42         long http_code;
  43         unsigned char real_sha1[20];
  44         SHA_CTX c;
  45         z_stream stream;
  46         int zret;
  47         int rename;
  48         struct active_request_slot *slot;
  49         struct object_request *next;
  50 };
  51
  52 struct alternates_request {
  53         char *base;
  54         char *url;
  55         struct buffer *buffer;
  56         struct active_request_slot *slot;
  57         int http_specific;
  58 };
  59
  60 static struct object_request *object_queue_head = NULL;
  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 = write(obj_req->local,
  71                                        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 = inflate(&obj_req->stream, Z_SYNC_FLUSH);
  83                 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(char *base);
  91
  92 static void process_object_response(void *callback_data);
  93
  94 static void start_object_request(struct object_request *obj_req)
  95 {
  96         char *hex = sha1_to_hex(obj_req->sha1);
  97         char prevfile[PATH_MAX];
  98         char *url;
  99         char *posn;
 100         int prevlocal;
 101         unsigned char prev_buf[PREV_BUF_SIZE];
 102         ssize_t prev_read = 0;
 103         long prev_posn = 0;
 104         char range[RANGE_HEADER_SIZE];
 105         struct curl_slist *range_header = NULL;
 106         struct active_request_slot *slot;
 107
 108         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
 109         unlink(prevfile);
 110         rename(obj_req->tmpfile, prevfile);
 111         unlink(obj_req->tmpfile);
 112
 113         if (obj_req->local != -1)
 114                 error("fd leakage in start: %d", obj_req->local);
 115         obj_req->local = open(obj_req->tmpfile,
 116                               O_WRONLY | O_CREAT | O_EXCL, 0666);
 117         /* This could have failed due to the "lazy directory creation";
 118          * try to mkdir the last path component.
 119          */
 120         if (obj_req->local < 0 && errno == ENOENT) {
 121                 char *dir = strrchr(obj_req->tmpfile, '/');
 122                 if (dir) {
 123                         *dir = 0;
 124                         mkdir(obj_req->tmpfile, 0777);
 125                         *dir = '/';
 126                 }
 127                 obj_req->local = open(obj_req->tmpfile,
 128                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
 129         }
 130
 131         if (obj_req->local < 0) {
 132                 obj_req->state = ABORTED;
 133                 error("Couldn't create temporary file %s for %s: %s\n",
 134                       obj_req->tmpfile, obj_req->filename, strerror(errno));
 135                 return;
 136         }
 137
 138         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 139
 140         inflateInit(&obj_req->stream);
 141
 142         SHA1_Init(&obj_req->c);
 143
 144         url = xmalloc(strlen(obj_req->repo->base) + 50);
 145         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 50);
 146         strcpy(url, obj_req->repo->base);
 147         posn = url + strlen(obj_req->repo->base);
 148         strcpy(posn, "objects/");
 149         posn += 8;
 150         memcpy(posn, hex, 2);
 151         posn += 2;
 152         *(posn++) = '/';
 153         strcpy(posn, hex + 2);
 154         strcpy(obj_req->url, url);
 155
 156         /* If a previous temp file is present, process what was already
 157            fetched. */
 158         prevlocal = open(prevfile, O_RDONLY);
 159         if (prevlocal != -1) {
 160                 do {
 161                         prev_read = read(prevlocal, prev_buf, PREV_BUF_SIZE);
 162                         if (prev_read>0) {
 163                                 if (fwrite_sha1_file(prev_buf,
 164                                                      1,
 165                                                      prev_read,
 166                                                      obj_req) == prev_read) {
 167                                         prev_posn += prev_read;
 168                                 } else {
 169                                         prev_read = -1;
 170                                 }
 171                         }
 172                 } while (prev_read > 0);
 173                 close(prevlocal);
 174         }
 175         unlink(prevfile);
 176
 177         /* Reset inflate/SHA1 if there was an error reading the previous temp
 178            file; also rewind to the beginning of the local file. */
 179         if (prev_read == -1) {
 180                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 181                 inflateInit(&obj_req->stream);
 182                 SHA1_Init(&obj_req->c);
 183                 if (prev_posn>0) {
 184                         prev_posn = 0;
 185                         lseek(obj_req->local, SEEK_SET, 0);
 186                         ftruncate(obj_req->local, 0);
 187                 }
 188         }
 189
 190         slot = get_active_slot();
 191         slot->callback_func = process_object_response;
 192         slot->callback_data = obj_req;
 193         obj_req->slot = slot;
 194
 195         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
 196         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
 197         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
 198         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 199         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 200
 201         /* If we have successfully processed data from a previous fetch
 202            attempt, only fetch the data we don't already have. */
 203         if (prev_posn>0) {
 204                 if (get_verbosely)
 205                         fprintf(stderr,
 206                                 "Resuming fetch of object %s at byte %ld\n",
 207                                 hex, prev_posn);
 208                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 209                 range_header = curl_slist_append(range_header, range);
 210                 curl_easy_setopt(slot->curl,
 211                                  CURLOPT_HTTPHEADER, range_header);
 212         }
 213
 214         /* Try to get the request started, abort the request on error */
 215         obj_req->state = ACTIVE;
 216         if (!start_active_slot(slot)) {
 217                 obj_req->state = ABORTED;
 218                 obj_req->slot = NULL;
 219                 close(obj_req->local); obj_req->local = -1;
 220                 free(obj_req->url);
 221                 return;
 222         }
 223 }
 224
 225 static void finish_object_request(struct object_request *obj_req)
 226 {
 227         struct stat st;
 228
 229         fchmod(obj_req->local, 0444);
 230         close(obj_req->local); obj_req->local = -1;
 231
 232         if (obj_req->http_code == 416) {
 233                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 234         } else if (obj_req->curl_result != CURLE_OK) {
 235                 if (stat(obj_req->tmpfile, &st) == 0)
 236                         if (st.st_size == 0)
 237                                 unlink(obj_req->tmpfile);
 238                 return;
 239         }
 240
 241         inflateEnd(&obj_req->stream);
 242         SHA1_Final(obj_req->real_sha1, &obj_req->c);
 243         if (obj_req->zret != Z_STREAM_END) {
 244                 unlink(obj_req->tmpfile);
 245                 return;
 246         }
 247         if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
 248                 unlink(obj_req->tmpfile);
 249                 return;
 250         }
 251         obj_req->rename =
 252                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 253
 254         if (obj_req->rename == 0)
 255                 pull_say("got %s\n", sha1_to_hex(obj_req->sha1));
 256 }
 257
 258 static void process_object_response(void *callback_data)
 259 {
 260         struct object_request *obj_req =
 261                 (struct object_request *)callback_data;
 262
 263         obj_req->curl_result = obj_req->slot->curl_result;
 264         obj_req->http_code = obj_req->slot->http_code;
 265         obj_req->slot = NULL;
 266         obj_req->state = COMPLETE;
 267
 268         /* Use alternates if necessary */
 269         if (obj_req->http_code == 404 ||
 270             obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE) {
 271                 fetch_alternates(alt->base);
 272                 if (obj_req->repo->next != NULL) {
 273                         obj_req->repo =
 274                                 obj_req->repo->next;
 275                         close(obj_req->local);
 276                         obj_req->local = -1;
 277                         start_object_request(obj_req);
 278                         return;
 279                 }
 280         }
 281
 282         finish_object_request(obj_req);
 283 }
 284
 285 static void release_object_request(struct object_request *obj_req)
 286 {
 287         struct object_request *entry = object_queue_head;
 288
 289         if (obj_req->local != -1)
 290                 error("fd leakage in release: %d", obj_req->local);
 291         if (obj_req == object_queue_head) {
 292                 object_queue_head = obj_req->next;
 293         } else {
 294                 while (entry->next != NULL && entry->next != obj_req)
 295                         entry = entry->next;
 296                 if (entry->next == obj_req)
 297                         entry->next = entry->next->next;
 298         }
 299
 300         free(obj_req->url);
 301         free(obj_req);
 302 }
 303
 304 #ifdef USE_CURL_MULTI
 305 void fill_active_slots(void)
 306 {
 307         struct object_request *obj_req = object_queue_head;
 308         struct active_request_slot *slot = active_queue_head;
 309         int num_transfers;
 310
 311         while (active_requests < max_requests && obj_req != NULL) {
 312                 if (obj_req->state == WAITING) {
 313                         if (has_sha1_file(obj_req->sha1))
 314                                 release_object_request(obj_req);
 315                         else
 316                                 start_object_request(obj_req);
 317                         curl_multi_perform(curlm, &num_transfers);
 318                 }
 319                 obj_req = obj_req->next;
 320         }
 321
 322         while (slot != NULL) {
 323                 if (!slot->in_use && slot->curl != NULL) {
 324                         curl_easy_cleanup(slot->curl);
 325                         slot->curl = NULL;
 326                 }
 327                 slot = slot->next;
 328         }
 329 }
 330 #endif
 331
 332 void prefetch(unsigned char *sha1)
 333 {
 334         struct object_request *newreq;
 335         struct object_request *tail;
 336         char *filename = sha1_file_name(sha1);
 337
 338         newreq = xmalloc(sizeof(*newreq));
 339         memcpy(newreq->sha1, sha1, 20);
 340         newreq->repo = 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->next = NULL;
 348
 349         if (object_queue_head == NULL) {
 350                 object_queue_head = newreq;
 351         } else {
 352                 tail = object_queue_head;
 353                 while (tail->next != NULL) {
 354                         tail = tail->next;
 355                 }
 356                 tail->next = newreq;
 357         }
 358
 359 #ifdef USE_CURL_MULTI
 360         fill_active_slots();
 361         step_active_slots();
 362 #endif
 363 }
 364
 365 static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 366 {
 367         char *hex = sha1_to_hex(sha1);
 368         char *filename;
 369         char *url;
 370         char tmpfile[PATH_MAX];
 371         long prev_posn = 0;
 372         char range[RANGE_HEADER_SIZE];
 373         struct curl_slist *range_header = NULL;
 374
 375         FILE *indexfile;
 376         struct active_request_slot *slot;
 377         struct slot_results results;
 378
 379         if (has_pack_index(sha1))
 380                 return 0;
 381
 382         if (get_verbosely)
 383                 fprintf(stderr, "Getting index for pack %s\n", hex);
 384
 385         url = xmalloc(strlen(repo->base) + 64);
 386         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
 387
 388         filename = sha1_pack_index_name(sha1);
 389         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 390         indexfile = fopen(tmpfile, "a");
 391         if (!indexfile)
 392                 return error("Unable to open local file %s for pack index",
 393                              filename);
 394
 395         slot = get_active_slot();
 396         slot->results = &results;
 397         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
 398         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 399         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 400         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 401         slot->local = indexfile;
 402
 403         /* If there is data present from a previous transfer attempt,
 404            resume where it left off */
 405         prev_posn = ftell(indexfile);
 406         if (prev_posn>0) {
 407                 if (get_verbosely)
 408                         fprintf(stderr,
 409                                 "Resuming fetch of index for pack %s at byte %ld\n",
 410                                 hex, prev_posn);
 411                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 412                 range_header = curl_slist_append(range_header, range);
 413                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 414         }
 415
 416         if (start_active_slot(slot)) {
 417                 run_active_slot(slot);
 418                 if (results.curl_result != CURLE_OK) {
 419                         fclose(indexfile);
 420                         return error("Unable to get pack index %s\n%s", url,
 421                                      curl_errorstr);
 422                 }
 423         } else {
 424                 fclose(indexfile);
 425                 return error("Unable to start request");
 426         }
 427
 428         fclose(indexfile);
 429
 430         return move_temp_to_file(tmpfile, filename);
 431 }
 432
 433 static int setup_index(struct alt_base *repo, unsigned char *sha1)
 434 {
 435         struct packed_git *new_pack;
 436         if (has_pack_file(sha1))
 437                 return 0; // don't list this as something we can get
 438
 439         if (fetch_index(repo, sha1))
 440                 return -1;
 441
 442         new_pack = parse_pack_index(sha1);
 443         new_pack->next = repo->packs;
 444         repo->packs = new_pack;
 445         return 0;
 446 }
 447
 448 static void process_alternates_response(void *callback_data)
 449 {
 450         struct alternates_request *alt_req =
 451                 (struct alternates_request *)callback_data;
 452         struct active_request_slot *slot = alt_req->slot;
 453         struct alt_base *tail = alt;
 454         char *base = alt_req->base;
 455         static const char null_byte = '\0';
 456         char *data;
 457         int i = 0;
 458
 459         if (alt_req->http_specific) {
 460                 if (slot->curl_result != CURLE_OK ||
 461                     !alt_req->buffer->posn) {
 462
 463                         /* Try reusing the slot to get non-http alternates */
 464                         alt_req->http_specific = 0;
 465                         sprintf(alt_req->url, "%s/objects/info/alternates",
 466                                 base);
 467                         curl_easy_setopt(slot->curl, CURLOPT_URL,
 468                                          alt_req->url);
 469                         active_requests++;
 470                         slot->in_use = 1;
 471                         if (start_active_slot(slot)) {
 472                                 return;
 473                         } else {
 474                                 got_alternates = -1;
 475                                 slot->in_use = 0;
 476                                 return;
 477                         }
 478                 }
 479         } else if (slot->curl_result != CURLE_OK) {
 480                 if (slot->http_code != 404 &&
 481                     slot->curl_result != CURLE_FILE_COULDNT_READ_FILE) {
 482                         got_alternates = -1;
 483                         return;
 484                 }
 485         }
 486
 487         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 488         alt_req->buffer->posn--;
 489         data = alt_req->buffer->buffer;
 490
 491         while (i < alt_req->buffer->posn) {
 492                 int posn = i;
 493                 while (posn < alt_req->buffer->posn && data[posn] != '\n')
 494                         posn++;
 495                 if (data[posn] == '\n') {
 496                         int okay = 0;
 497                         int serverlen = 0;
 498                         struct alt_base *newalt;
 499                         char *target = NULL;
 500                         if (data[i] == '/') {
 501                                 serverlen = strchr(base + 8, '/') - base;
 502                                 okay = 1;
 503                         } else if (!memcmp(data + i, "../", 3)) {
 504                                 i += 3;
 505                                 serverlen = strlen(base);
 506                                 while (i + 2 < posn &&
 507                                        !memcmp(data + i, "../", 3)) {
 508                                         do {
 509                                                 serverlen--;
 510                                         } while (serverlen &&
 511                                                  base[serverlen - 1] != '/');
 512                                         i += 3;
 513                                 }
 514                                 // If the server got removed, give up.
 515                                 okay = strchr(base, ':') - base + 3 <
 516                                         serverlen;
 517                         } else if (alt_req->http_specific) {
 518                                 char *colon = strchr(data + i, ':');
 519                                 char *slash = strchr(data + i, '/');
 520                                 if (colon && slash && colon < data + posn &&
 521                                     slash < data + posn && colon < slash) {
 522                                         okay = 1;
 523                                 }
 524                         }
 525                         // skip 'objects' at end
 526                         if (okay) {
 527                                 target = xmalloc(serverlen + posn - i - 6);
 528                                 strncpy(target, base, serverlen);
 529                                 strncpy(target + serverlen, data + i,
 530                                         posn - i - 7);
 531                                 target[serverlen + posn - i - 7] = '\0';
 532                                 if (get_verbosely)
 533                                         fprintf(stderr,
 534                                                 "Also look at %s\n", target);
 535                                 newalt = xmalloc(sizeof(*newalt));
 536                                 newalt->next = NULL;
 537                                 newalt->base = target;
 538                                 newalt->got_indices = 0;
 539                                 newalt->packs = NULL;
 540                                 while (tail->next != NULL)
 541                                         tail = tail->next;
 542                                 tail->next = newalt;
 543                         }
 544                 }
 545                 i = posn + 1;
 546         }
 547
 548         got_alternates = 1;
 549 }
 550
 551 static void fetch_alternates(char *base)
 552 {
 553         struct buffer buffer;
 554         char *url;
 555         char *data;
 556         struct active_request_slot *slot;
 557         struct alternates_request alt_req;
 558
 559         /* If another request has already started fetching alternates,
 560            wait for them to arrive and return to processing this request's
 561            curl message */
 562 #ifdef USE_CURL_MULTI
 563         while (got_alternates == 0) {
 564                 step_active_slots();
 565         }
 566 #endif
 567
 568         /* Nothing to do if they've already been fetched */
 569         if (got_alternates == 1)
 570                 return;
 571
 572         /* Start the fetch */
 573         got_alternates = 0;
 574
 575         data = xmalloc(4096);
 576         buffer.size = 4096;
 577         buffer.posn = 0;
 578         buffer.buffer = data;
 579
 580         if (get_verbosely)
 581                 fprintf(stderr, "Getting alternates list for %s\n", base);
 582
 583         url = xmalloc(strlen(base) + 31);
 584         sprintf(url, "%s/objects/info/http-alternates", base);
 585
 586         /* Use a callback to process the result, since another request
 587            may fail and need to have alternates loaded before continuing */
 588         slot = get_active_slot();
 589         slot->callback_func = process_alternates_response;
 590         slot->callback_data = &alt_req;
 591
 592         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 593         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 594         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 595
 596         alt_req.base = base;
 597         alt_req.url = url;
 598         alt_req.buffer = &buffer;
 599         alt_req.http_specific = 1;
 600         alt_req.slot = slot;
 601
 602         if (start_active_slot(slot))
 603                 run_active_slot(slot);
 604         else
 605                 got_alternates = -1;
 606
 607         free(data);
 608         free(url);
 609 }
 610
 611 static int fetch_indices(struct alt_base *repo)
 612 {
 613         unsigned char sha1[20];
 614         char *url;
 615         struct buffer buffer;
 616         char *data;
 617         int i = 0;
 618
 619         struct active_request_slot *slot;
 620         struct slot_results results;
 621
 622         if (repo->got_indices)
 623                 return 0;
 624
 625         data = xmalloc(4096);
 626         buffer.size = 4096;
 627         buffer.posn = 0;
 628         buffer.buffer = data;
 629
 630         if (get_verbosely)
 631                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
 632
 633         url = xmalloc(strlen(repo->base) + 21);
 634         sprintf(url, "%s/objects/info/packs", repo->base);
 635
 636         slot = get_active_slot();
 637         slot->results = &results;
 638         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 639         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 640         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 641         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 642         if (start_active_slot(slot)) {
 643                 run_active_slot(slot);
 644                 if (results.curl_result != CURLE_OK) {
 645                         if (results.http_code == 404 ||
 646                             results.curl_result == CURLE_FILE_COULDNT_READ_FILE) {
 647                                 repo->got_indices = 1;
 648                                 free(buffer.buffer);
 649                                 return 0;
 650                         } else {
 651                                 repo->got_indices = 0;
 652                                 free(buffer.buffer);
 653                                 return error("%s", curl_errorstr);
 654                         }
 655                 }
 656         } else {
 657                 repo->got_indices = 0;
 658                 free(buffer.buffer);
 659                 return error("Unable to start request");
 660         }
 661
 662         data = buffer.buffer;
 663         while (i < buffer.posn) {
 664                 switch (data[i]) {
 665                 case 'P':
 666                         i++;
 667                         if (i + 52 <= buffer.posn &&
 668                             !strncmp(data + i, " pack-", 6) &&
 669                             !strncmp(data + i + 46, ".pack\n", 6)) {
 670                                 get_sha1_hex(data + i + 6, sha1);
 671                                 setup_index(repo, sha1);
 672                                 i += 51;
 673                                 break;
 674                         }
 675                 default:
 676                         while (i < buffer.posn && data[i] != '\n')
 677                                 i++;
 678                 }
 679                 i++;
 680         }
 681
 682         free(buffer.buffer);
 683         repo->got_indices = 1;
 684         return 0;
 685 }
 686
 687 static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
 688 {
 689         char *url;
 690         struct packed_git *target;
 691         struct packed_git **lst;
 692         FILE *packfile;
 693         char *filename;
 694         char tmpfile[PATH_MAX];
 695         int ret;
 696         long prev_posn = 0;
 697         char range[RANGE_HEADER_SIZE];
 698         struct curl_slist *range_header = NULL;
 699
 700         struct active_request_slot *slot;
 701         struct slot_results results;
 702
 703         if (fetch_indices(repo))
 704                 return -1;
 705         target = find_sha1_pack(sha1, repo->packs);
 706         if (!target)
 707                 return -1;
 708
 709         if (get_verbosely) {
 710                 fprintf(stderr, "Getting pack %s\n",
 711                         sha1_to_hex(target->sha1));
 712                 fprintf(stderr, " which contains %s\n",
 713                         sha1_to_hex(sha1));
 714         }
 715
 716         url = xmalloc(strlen(repo->base) + 65);
 717         sprintf(url, "%s/objects/pack/pack-%s.pack",
 718                 repo->base, sha1_to_hex(target->sha1));
 719
 720         filename = sha1_pack_name(target->sha1);
 721         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 722         packfile = fopen(tmpfile, "a");
 723         if (!packfile)
 724                 return error("Unable to open local file %s for pack",
 725                              filename);
 726
 727         slot = get_active_slot();
 728         slot->results = &results;
 729         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
 730         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 731         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 732         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 733         slot->local = packfile;
 734
 735         /* If there is data present from a previous transfer attempt,
 736            resume where it left off */
 737         prev_posn = ftell(packfile);
 738         if (prev_posn>0) {
 739                 if (get_verbosely)
 740                         fprintf(stderr,
 741                                 "Resuming fetch of pack %s at byte %ld\n",
 742                                 sha1_to_hex(target->sha1), prev_posn);
 743                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 744                 range_header = curl_slist_append(range_header, range);
 745                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 746         }
 747
 748         if (start_active_slot(slot)) {
 749                 run_active_slot(slot);
 750                 if (results.curl_result != CURLE_OK) {
 751                         fclose(packfile);
 752                         return error("Unable to get pack file %s\n%s", url,
 753                                      curl_errorstr);
 754                 }
 755         } else {
 756                 fclose(packfile);
 757                 return error("Unable to start request");
 758         }
 759
 760         fclose(packfile);
 761
 762         ret = move_temp_to_file(tmpfile, filename);
 763         if (ret)
 764                 return ret;
 765
 766         lst = &repo->packs;
 767         while (*lst != target)
 768                 lst = &((*lst)->next);
 769         *lst = (*lst)->next;
 770
 771         if (verify_pack(target, 0))
 772                 return -1;
 773         install_packed_git(target);
 774
 775         return 0;
 776 }
 777
 778 static int fetch_object(struct alt_base *repo, unsigned char *sha1)
 779 {
 780         char *hex = sha1_to_hex(sha1);
 781         int ret = 0;
 782         struct object_request *obj_req = object_queue_head;
 783
 784         while (obj_req != NULL && memcmp(obj_req->sha1, sha1, 20))
 785                 obj_req = obj_req->next;
 786         if (obj_req == NULL)
 787                 return error("Couldn't find request for %s in the queue", hex);
 788
 789         if (has_sha1_file(obj_req->sha1)) {
 790                 release_object_request(obj_req);
 791                 return 0;
 792         }
 793
 794 #ifdef USE_CURL_MULTI
 795         while (obj_req->state == WAITING) {
 796                 step_active_slots();
 797         }
 798 #else
 799         start_object_request(obj_req);
 800 #endif
 801
 802         while (obj_req->state == ACTIVE) {
 803                 run_active_slot(obj_req->slot);
 804         }
 805         if (obj_req->local != -1) {
 806                 close(obj_req->local); obj_req->local = -1;
 807         }
 808
 809         if (obj_req->state == ABORTED) {
 810                 ret = error("Request for %s aborted", hex);
 811         } else if (obj_req->curl_result != CURLE_OK &&
 812                    obj_req->http_code != 416) {
 813                 if (obj_req->http_code == 404 ||
 814                     obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE)
 815                         ret = -1; /* Be silent, it is probably in a pack. */
 816                 else
 817                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 818                                     obj_req->errorstr, obj_req->curl_result,
 819                                     obj_req->http_code, hex);
 820         } else if (obj_req->zret != Z_STREAM_END) {
 821                 ret = error("File %s (%s) corrupt\n", hex, obj_req->url);
 822         } else if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
 823                 ret = error("File %s has bad hash\n", hex);
 824         } else if (obj_req->rename < 0) {
 825                 ret = error("unable to write sha1 filename %s: %s",
 826                             obj_req->filename,
 827                             strerror(obj_req->rename));
 828         }
 829
 830         release_object_request(obj_req);
 831         return ret;
 832 }
 833
 834 int fetch(unsigned char *sha1)
 835 {
 836         struct alt_base *altbase = alt;
 837
 838         if (!fetch_object(altbase, sha1))
 839                 return 0;
 840         while (altbase) {
 841                 if (!fetch_pack(altbase, sha1))
 842                         return 0;
 843                 fetch_alternates(alt->base);
 844                 altbase = altbase->next;
 845         }
 846         return error("Unable to find %s under %s\n", sha1_to_hex(sha1),
 847                      alt->base);
 848 }
 849
 850 static inline int needs_quote(int ch)
 851 {
 852         switch (ch) {
 853         case '/': case '-': case '.':
 854         case 'A'...'Z': case 'a'...'z': case '0'...'9':
 855                 return 0;
 856         default:
 857                 return 1;
 858         }
 859 }
 860
 861 static inline int hex(int v)
 862 {
 863         if (v < 10) return '0' + v;
 864         else return 'A' + v - 10;
 865 }
 866
 867 static char *quote_ref_url(const char *base, const char *ref)
 868 {
 869         const char *cp;
 870         char *dp, *qref;
 871         int len, baselen, ch;
 872
 873         baselen = strlen(base);
 874         len = baselen + 6; /* "refs/" + NUL */
 875         for (cp = ref; (ch = *cp) != 0; cp++, len++)
 876                 if (needs_quote(ch))
 877                         len += 2; /* extra two hex plus replacement % */
 878         qref = xmalloc(len);
 879         memcpy(qref, base, baselen);
 880         memcpy(qref + baselen, "refs/", 5);
 881         for (cp = ref, dp = qref + baselen + 5; (ch = *cp) != 0; cp++) {
 882                 if (needs_quote(ch)) {
 883                         *dp++ = '%';
 884                         *dp++ = hex((ch >> 4) & 0xF);
 885                         *dp++ = hex(ch & 0xF);
 886                 }
 887                 else
 888                         *dp++ = ch;
 889         }
 890         *dp = 0;
 891
 892         return qref;
 893 }
 894
 895 int fetch_ref(char *ref, unsigned char *sha1)
 896 {
 897         char *url;
 898         char hex[42];
 899         struct buffer buffer;
 900         char *base = alt->base;
 901         struct active_request_slot *slot;
 902         struct slot_results results;
 903         buffer.size = 41;
 904         buffer.posn = 0;
 905         buffer.buffer = hex;
 906         hex[41] = '\0';
 907
 908         url = quote_ref_url(base, ref);
 909         slot = get_active_slot();
 910         slot->results = &results;
 911         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 912         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 913         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 914         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 915         if (start_active_slot(slot)) {
 916                 run_active_slot(slot);
 917                 if (results.curl_result != CURLE_OK)
 918                         return error("Couldn't get %s for %s\n%s",
 919                                      url, ref, curl_errorstr);
 920         } else {
 921                 return error("Unable to start request");
 922         }
 923
 924         hex[40] = '\0';
 925         get_sha1_hex(hex, sha1);
 926         return 0;
 927 }
 928
 929 int main(int argc, char **argv)
 930 {
 931         char *commit_id;
 932         char *url;
 933         int arg = 1;
 934         int rc = 0;
 935
 936         setup_git_directory();
 937
 938         while (arg < argc && argv[arg][0] == '-') {
 939                 if (argv[arg][1] == 't') {
 940                         get_tree = 1;
 941                 } else if (argv[arg][1] == 'c') {
 942                         get_history = 1;
 943                 } else if (argv[arg][1] == 'a') {
 944                         get_all = 1;
 945                         get_tree = 1;
 946                         get_history = 1;
 947                 } else if (argv[arg][1] == 'v') {
 948                         get_verbosely = 1;
 949                 } else if (argv[arg][1] == 'w') {
 950                         write_ref = argv[arg + 1];
 951                         arg++;
 952                 } else if (!strcmp(argv[arg], "--recover")) {
 953                         get_recover = 1;
 954                 }
 955                 arg++;
 956         }
 957         if (argc < arg + 2) {
 958                 usage("git-http-fetch [-c] [-t] [-a] [-d] [-v] [--recover] [-w ref] commit-id url");
 959                 return 1;
 960         }
 961         commit_id = argv[arg];
 962         url = argv[arg + 1];
 963
 964         http_init();
 965
 966         no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
 967
 968         alt = xmalloc(sizeof(*alt));
 969         alt->base = url;
 970         alt->got_indices = 0;
 971         alt->packs = NULL;
 972         alt->next = NULL;
 973
 974         if (pull(commit_id))
 975                 rc = 1;
 976
 977         curl_slist_free_all(no_pragma_header);
 978
 979         http_cleanup();
 980
 981         return rc;
 982 }