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 buffer *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 int missing__target(int code, int result)
  94 {
  95         return  /* file:// URL -- do we ever use one??? */
  96                 (result == CURLE_FILE_COULDNT_READ_FILE) ||
  97                 /* http:// and https:// URL */
  98                 (code == 404 && result == CURLE_HTTP_RETURNED_ERROR) ||
  99                 /* ftp:// URL */
 100                 (code == 550 && result == CURLE_FTP_COULDNT_RETR_FILE)
 101                 ;
 102 }
 103
 104 #define missing_target(a) missing__target((a)->http_code, (a)->curl_result)
 105
 106 static void fetch_alternates(struct walker *walker, const char *base);
 107
 108 static void process_object_response(void *callback_data);
 109
 110 static void start_object_request(struct walker *walker,
 111                                  struct object_request *obj_req)
 112 {
 113         char *hex = sha1_to_hex(obj_req->sha1);
 114         char prevfile[PATH_MAX];
 115         char *url;
 116         char *posn;
 117         int prevlocal;
 118         unsigned char prev_buf[PREV_BUF_SIZE];
 119         ssize_t prev_read = 0;
 120         long prev_posn = 0;
 121         char range[RANGE_HEADER_SIZE];
 122         struct curl_slist *range_header = NULL;
 123         struct active_request_slot *slot;
 124         struct walker_data *data = walker->data;
 125
 126         snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
 127         unlink(prevfile);
 128         rename(obj_req->tmpfile, prevfile);
 129         unlink(obj_req->tmpfile);
 130
 131         if (obj_req->local != -1)
 132                 error("fd leakage in start: %d", obj_req->local);
 133         obj_req->local = open(obj_req->tmpfile,
 134                               O_WRONLY | O_CREAT | O_EXCL, 0666);
 135         /* This could have failed due to the "lazy directory creation";
 136          * try to mkdir the last path component.
 137          */
 138         if (obj_req->local < 0 && errno == ENOENT) {
 139                 char *dir = strrchr(obj_req->tmpfile, '/');
 140                 if (dir) {
 141                         *dir = 0;
 142                         mkdir(obj_req->tmpfile, 0777);
 143                         *dir = '/';
 144                 }
 145                 obj_req->local = open(obj_req->tmpfile,
 146                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
 147         }
 148
 149         if (obj_req->local < 0) {
 150                 obj_req->state = ABORTED;
 151                 error("Couldn't create temporary file %s for %s: %s",
 152                       obj_req->tmpfile, obj_req->filename, strerror(errno));
 153                 return;
 154         }
 155
 156         memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 157
 158         inflateInit(&obj_req->stream);
 159
 160         SHA1_Init(&obj_req->c);
 161
 162         url = xmalloc(strlen(obj_req->repo->base) + 51);
 163         obj_req->url = xmalloc(strlen(obj_req->repo->base) + 51);
 164         strcpy(url, obj_req->repo->base);
 165         posn = url + strlen(obj_req->repo->base);
 166         strcpy(posn, "/objects/");
 167         posn += 9;
 168         memcpy(posn, hex, 2);
 169         posn += 2;
 170         *(posn++) = '/';
 171         strcpy(posn, hex + 2);
 172         strcpy(obj_req->url, url);
 173
 174         /* If a previous temp file is present, process what was already
 175            fetched. */
 176         prevlocal = open(prevfile, O_RDONLY);
 177         if (prevlocal != -1) {
 178                 do {
 179                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
 180                         if (prev_read>0) {
 181                                 if (fwrite_sha1_file(prev_buf,
 182                                                      1,
 183                                                      prev_read,
 184                                                      obj_req) == prev_read) {
 185                                         prev_posn += prev_read;
 186                                 } else {
 187                                         prev_read = -1;
 188                                 }
 189                         }
 190                 } while (prev_read > 0);
 191                 close(prevlocal);
 192         }
 193         unlink(prevfile);
 194
 195         /* Reset inflate/SHA1 if there was an error reading the previous temp
 196            file; also rewind to the beginning of the local file. */
 197         if (prev_read == -1) {
 198                 memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 199                 inflateInit(&obj_req->stream);
 200                 SHA1_Init(&obj_req->c);
 201                 if (prev_posn>0) {
 202                         prev_posn = 0;
 203                         lseek(obj_req->local, 0, SEEK_SET);
 204                         ftruncate(obj_req->local, 0);
 205                 }
 206         }
 207
 208         slot = get_active_slot();
 209         slot->callback_func = process_object_response;
 210         slot->callback_data = obj_req;
 211         obj_req->slot = slot;
 212
 213         curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
 214         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
 215         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
 216         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 217         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 218
 219         /* If we have successfully processed data from a previous fetch
 220            attempt, only fetch the data we don't already have. */
 221         if (prev_posn>0) {
 222                 if (walker->get_verbosely)
 223                         fprintf(stderr,
 224                                 "Resuming fetch of object %s at byte %ld\n",
 225                                 hex, prev_posn);
 226                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 227                 range_header = curl_slist_append(range_header, range);
 228                 curl_easy_setopt(slot->curl,
 229                                  CURLOPT_HTTPHEADER, range_header);
 230         }
 231
 232         /* Try to get the request started, abort the request on error */
 233         obj_req->state = ACTIVE;
 234         if (!start_active_slot(slot)) {
 235                 obj_req->state = ABORTED;
 236                 obj_req->slot = NULL;
 237                 close(obj_req->local); obj_req->local = -1;
 238                 free(obj_req->url);
 239                 return;
 240         }
 241 }
 242
 243 static void finish_object_request(struct object_request *obj_req)
 244 {
 245         struct stat st;
 246
 247         fchmod(obj_req->local, 0444);
 248         close(obj_req->local); obj_req->local = -1;
 249
 250         if (obj_req->http_code == 416) {
 251                 fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 252         } else if (obj_req->curl_result != CURLE_OK) {
 253                 if (stat(obj_req->tmpfile, &st) == 0)
 254                         if (st.st_size == 0)
 255                                 unlink(obj_req->tmpfile);
 256                 return;
 257         }
 258
 259         inflateEnd(&obj_req->stream);
 260         SHA1_Final(obj_req->real_sha1, &obj_req->c);
 261         if (obj_req->zret != Z_STREAM_END) {
 262                 unlink(obj_req->tmpfile);
 263                 return;
 264         }
 265         if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 266                 unlink(obj_req->tmpfile);
 267                 return;
 268         }
 269         obj_req->rename =
 270                 move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 271
 272         if (obj_req->rename == 0)
 273                 walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
 274 }
 275
 276 static void process_object_response(void *callback_data)
 277 {
 278         struct object_request *obj_req =
 279                 (struct object_request *)callback_data;
 280         struct walker *walker = obj_req->walker;
 281         struct walker_data *data = walker->data;
 282         struct alt_base *alt = data->alt;
 283
 284         obj_req->curl_result = obj_req->slot->curl_result;
 285         obj_req->http_code = obj_req->slot->http_code;
 286         obj_req->slot = NULL;
 287         obj_req->state = COMPLETE;
 288
 289         /* Use alternates if necessary */
 290         if (missing_target(obj_req)) {
 291                 fetch_alternates(walker, alt->base);
 292                 if (obj_req->repo->next != NULL) {
 293                         obj_req->repo =
 294                                 obj_req->repo->next;
 295                         close(obj_req->local);
 296                         obj_req->local = -1;
 297                         start_object_request(walker, obj_req);
 298                         return;
 299                 }
 300         }
 301
 302         finish_object_request(obj_req);
 303 }
 304
 305 static void release_object_request(struct object_request *obj_req)
 306 {
 307         struct object_request *entry = object_queue_head;
 308
 309         if (obj_req->local != -1)
 310                 error("fd leakage in release: %d", obj_req->local);
 311         if (obj_req == object_queue_head) {
 312                 object_queue_head = obj_req->next;
 313         } else {
 314                 while (entry->next != NULL && entry->next != obj_req)
 315                         entry = entry->next;
 316                 if (entry->next == obj_req)
 317                         entry->next = entry->next->next;
 318         }
 319
 320         free(obj_req->url);
 321         free(obj_req);
 322 }
 323
 324 #ifdef USE_CURL_MULTI
 325 static int fill_active_slot(struct walker *walker)
 326 {
 327         struct object_request *obj_req;
 328
 329         for (obj_req = object_queue_head; obj_req; obj_req = obj_req->next) {
 330                 if (obj_req->state == WAITING) {
 331                         if (has_sha1_file(obj_req->sha1))
 332                                 obj_req->state = COMPLETE;
 333                         else {
 334                                 start_object_request(walker, obj_req);
 335                                 return 1;
 336                         }
 337                 }
 338         }
 339         return 0;
 340 }
 341 #endif
 342
 343 static void prefetch(struct walker *walker, unsigned char *sha1)
 344 {
 345         struct object_request *newreq;
 346         struct object_request *tail;
 347         struct walker_data *data = walker->data;
 348         char *filename = sha1_file_name(sha1);
 349
 350         newreq = xmalloc(sizeof(*newreq));
 351         newreq->walker = walker;
 352         hashcpy(newreq->sha1, sha1);
 353         newreq->repo = data->alt;
 354         newreq->url = NULL;
 355         newreq->local = -1;
 356         newreq->state = WAITING;
 357         snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
 358         snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
 359                  "%s.temp", filename);
 360         newreq->slot = NULL;
 361         newreq->next = NULL;
 362
 363         if (object_queue_head == NULL) {
 364                 object_queue_head = newreq;
 365         } else {
 366                 tail = object_queue_head;
 367                 while (tail->next != NULL) {
 368                         tail = tail->next;
 369                 }
 370                 tail->next = newreq;
 371         }
 372
 373 #ifdef USE_CURL_MULTI
 374         fill_active_slots();
 375         step_active_slots();
 376 #endif
 377 }
 378
 379 static int fetch_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 380 {
 381         char *hex = sha1_to_hex(sha1);
 382         char *filename;
 383         char *url;
 384         char tmpfile[PATH_MAX];
 385         long prev_posn = 0;
 386         char range[RANGE_HEADER_SIZE];
 387         struct curl_slist *range_header = NULL;
 388         struct walker_data *data = walker->data;
 389
 390         FILE *indexfile;
 391         struct active_request_slot *slot;
 392         struct slot_results results;
 393
 394         if (has_pack_index(sha1))
 395                 return 0;
 396
 397         if (walker->get_verbosely)
 398                 fprintf(stderr, "Getting index for pack %s\n", hex);
 399
 400         url = xmalloc(strlen(repo->base) + 64);
 401         sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
 402
 403         filename = sha1_pack_index_name(sha1);
 404         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 405         indexfile = fopen(tmpfile, "a");
 406         if (!indexfile)
 407                 return error("Unable to open local file %s for pack index",
 408                              filename);
 409
 410         slot = get_active_slot();
 411         slot->results = &results;
 412         curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
 413         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 414         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 415         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 416         slot->local = indexfile;
 417
 418         /* If there is data present from a previous transfer attempt,
 419            resume where it left off */
 420         prev_posn = ftell(indexfile);
 421         if (prev_posn>0) {
 422                 if (walker->get_verbosely)
 423                         fprintf(stderr,
 424                                 "Resuming fetch of index for pack %s at byte %ld\n",
 425                                 hex, prev_posn);
 426                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 427                 range_header = curl_slist_append(range_header, range);
 428                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 429         }
 430
 431         if (start_active_slot(slot)) {
 432                 run_active_slot(slot);
 433                 if (results.curl_result != CURLE_OK) {
 434                         fclose(indexfile);
 435                         return error("Unable to get pack index %s\n%s", url,
 436                                      curl_errorstr);
 437                 }
 438         } else {
 439                 fclose(indexfile);
 440                 return error("Unable to start request");
 441         }
 442
 443         fclose(indexfile);
 444
 445         return move_temp_to_file(tmpfile, filename);
 446 }
 447
 448 static int setup_index(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 449 {
 450         struct packed_git *new_pack;
 451         if (has_pack_file(sha1))
 452                 return 0; /* don't list this as something we can get */
 453
 454         if (fetch_index(walker, repo, sha1))
 455                 return -1;
 456
 457         new_pack = parse_pack_index(sha1);
 458         new_pack->next = repo->packs;
 459         repo->packs = new_pack;
 460         return 0;
 461 }
 462
 463 static void process_alternates_response(void *callback_data)
 464 {
 465         struct alternates_request *alt_req =
 466                 (struct alternates_request *)callback_data;
 467         struct walker *walker = alt_req->walker;
 468         struct walker_data *cdata = walker->data;
 469         struct active_request_slot *slot = alt_req->slot;
 470         struct alt_base *tail = cdata->alt;
 471         const char *base = alt_req->base;
 472         static const char null_byte = '\0';
 473         char *data;
 474         int i = 0;
 475
 476         if (alt_req->http_specific) {
 477                 if (slot->curl_result != CURLE_OK ||
 478                     !alt_req->buffer->posn) {
 479
 480                         /* Try reusing the slot to get non-http alternates */
 481                         alt_req->http_specific = 0;
 482                         sprintf(alt_req->url, "%s/objects/info/alternates",
 483                                 base);
 484                         curl_easy_setopt(slot->curl, CURLOPT_URL,
 485                                          alt_req->url);
 486                         active_requests++;
 487                         slot->in_use = 1;
 488                         if (slot->finished != NULL)
 489                                 (*slot->finished) = 0;
 490                         if (!start_active_slot(slot)) {
 491                                 cdata->got_alternates = -1;
 492                                 slot->in_use = 0;
 493                                 if (slot->finished != NULL)
 494                                         (*slot->finished) = 1;
 495                         }
 496                         return;
 497                 }
 498         } else if (slot->curl_result != CURLE_OK) {
 499                 if (!missing_target(slot)) {
 500                         cdata->got_alternates = -1;
 501                         return;
 502                 }
 503         }
 504
 505         fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 506         alt_req->buffer->posn--;
 507         data = alt_req->buffer->buffer;
 508
 509         while (i < alt_req->buffer->posn) {
 510                 int posn = i;
 511                 while (posn < alt_req->buffer->posn && data[posn] != '\n')
 512                         posn++;
 513                 if (data[posn] == '\n') {
 514                         int okay = 0;
 515                         int serverlen = 0;
 516                         struct alt_base *newalt;
 517                         char *target = NULL;
 518                         if (data[i] == '/') {
 519                                 /* This counts
 520                                  * http://git.host/pub/scm/linux.git/
 521                                  * -----------here^
 522                                  * so memcpy(dst, base, serverlen) will
 523                                  * copy up to "...git.host".
 524                                  */
 525                                 const char *colon_ss = strstr(base,"://");
 526                                 if (colon_ss) {
 527                                         serverlen = (strchr(colon_ss + 3, '/')
 528                                                      - base);
 529                                         okay = 1;
 530                                 }
 531                         } else if (!memcmp(data + i, "../", 3)) {
 532                                 /* Relative URL; chop the corresponding
 533                                  * number of subpath from base (and ../
 534                                  * from data), and concatenate the result.
 535                                  *
 536                                  * The code first drops ../ from data, and
 537                                  * then drops one ../ from data and one path
 538                                  * from base.  IOW, one extra ../ is dropped
 539                                  * from data than path is dropped from base.
 540                                  *
 541                                  * This is not wrong.  The alternate in
 542                                  *     http://git.host/pub/scm/linux.git/
 543                                  * to borrow from
 544                                  *     http://git.host/pub/scm/linus.git/
 545                                  * is ../../linus.git/objects/.  You need
 546                                  * two ../../ to borrow from your direct
 547                                  * neighbour.
 548                                  */
 549                                 i += 3;
 550                                 serverlen = strlen(base);
 551                                 while (i + 2 < posn &&
 552                                        !memcmp(data + i, "../", 3)) {
 553                                         do {
 554                                                 serverlen--;
 555                                         } while (serverlen &&
 556                                                  base[serverlen - 1] != '/');
 557                                         i += 3;
 558                                 }
 559                                 /* If the server got removed, give up. */
 560                                 okay = strchr(base, ':') - base + 3 <
 561                                         serverlen;
 562                         } else if (alt_req->http_specific) {
 563                                 char *colon = strchr(data + i, ':');
 564                                 char *slash = strchr(data + i, '/');
 565                                 if (colon && slash && colon < data + posn &&
 566                                     slash < data + posn && colon < slash) {
 567                                         okay = 1;
 568                                 }
 569                         }
 570                         /* skip "objects\n" at end */
 571                         if (okay) {
 572                                 target = xmalloc(serverlen + posn - i - 6);
 573                                 memcpy(target, base, serverlen);
 574                                 memcpy(target + serverlen, data + i,
 575                                        posn - i - 7);
 576                                 target[serverlen + posn - i - 7] = 0;
 577                                 if (walker->get_verbosely)
 578                                         fprintf(stderr,
 579                                                 "Also look at %s\n", target);
 580                                 newalt = xmalloc(sizeof(*newalt));
 581                                 newalt->next = NULL;
 582                                 newalt->base = target;
 583                                 newalt->got_indices = 0;
 584                                 newalt->packs = NULL;
 585
 586                                 while (tail->next != NULL)
 587                                         tail = tail->next;
 588                                 tail->next = newalt;
 589                         }
 590                 }
 591                 i = posn + 1;
 592         }
 593
 594         cdata->got_alternates = 1;
 595 }
 596
 597 static void fetch_alternates(struct walker *walker, const char *base)
 598 {
 599         struct buffer buffer;
 600         char *url;
 601         char *data;
 602         struct active_request_slot *slot;
 603         struct alternates_request alt_req;
 604         struct walker_data *cdata = walker->data;
 605
 606         /* If another request has already started fetching alternates,
 607            wait for them to arrive and return to processing this request's
 608            curl message */
 609 #ifdef USE_CURL_MULTI
 610         while (cdata->got_alternates == 0) {
 611                 step_active_slots();
 612         }
 613 #endif
 614
 615         /* Nothing to do if they've already been fetched */
 616         if (cdata->got_alternates == 1)
 617                 return;
 618
 619         /* Start the fetch */
 620         cdata->got_alternates = 0;
 621
 622         data = xmalloc(4096);
 623         buffer.size = 4096;
 624         buffer.posn = 0;
 625         buffer.buffer = data;
 626
 627         if (walker->get_verbosely)
 628                 fprintf(stderr, "Getting alternates list for %s\n", base);
 629
 630         url = xmalloc(strlen(base) + 31);
 631         sprintf(url, "%s/objects/info/http-alternates", base);
 632
 633         /* Use a callback to process the result, since another request
 634            may fail and need to have alternates loaded before continuing */
 635         slot = get_active_slot();
 636         slot->callback_func = process_alternates_response;
 637         alt_req.walker = walker;
 638         slot->callback_data = &alt_req;
 639
 640         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 641         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 642         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 643
 644         alt_req.base = base;
 645         alt_req.url = url;
 646         alt_req.buffer = &buffer;
 647         alt_req.http_specific = 1;
 648         alt_req.slot = slot;
 649
 650         if (start_active_slot(slot))
 651                 run_active_slot(slot);
 652         else
 653                 cdata->got_alternates = -1;
 654
 655         free(data);
 656         free(url);
 657 }
 658
 659 static int fetch_indices(struct walker *walker, struct alt_base *repo)
 660 {
 661         unsigned char sha1[20];
 662         char *url;
 663         struct buffer buffer;
 664         char *data;
 665         int i = 0;
 666
 667         struct active_request_slot *slot;
 668         struct slot_results results;
 669
 670         if (repo->got_indices)
 671                 return 0;
 672
 673         data = xmalloc(4096);
 674         buffer.size = 4096;
 675         buffer.posn = 0;
 676         buffer.buffer = data;
 677
 678         if (walker->get_verbosely)
 679                 fprintf(stderr, "Getting pack list for %s\n", repo->base);
 680
 681         url = xmalloc(strlen(repo->base) + 21);
 682         sprintf(url, "%s/objects/info/packs", repo->base);
 683
 684         slot = get_active_slot();
 685         slot->results = &results;
 686         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 687         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 688         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 689         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 690         if (start_active_slot(slot)) {
 691                 run_active_slot(slot);
 692                 if (results.curl_result != CURLE_OK) {
 693                         if (missing_target(&results)) {
 694                                 repo->got_indices = 1;
 695                                 free(buffer.buffer);
 696                                 return 0;
 697                         } else {
 698                                 repo->got_indices = 0;
 699                                 free(buffer.buffer);
 700                                 return error("%s", curl_errorstr);
 701                         }
 702                 }
 703         } else {
 704                 repo->got_indices = 0;
 705                 free(buffer.buffer);
 706                 return error("Unable to start request");
 707         }
 708
 709         data = buffer.buffer;
 710         while (i < buffer.posn) {
 711                 switch (data[i]) {
 712                 case 'P':
 713                         i++;
 714                         if (i + 52 <= buffer.posn &&
 715                             !prefixcmp(data + i, " pack-") &&
 716                             !prefixcmp(data + i + 46, ".pack\n")) {
 717                                 get_sha1_hex(data + i + 6, sha1);
 718                                 setup_index(walker, repo, sha1);
 719                                 i += 51;
 720                                 break;
 721                         }
 722                 default:
 723                         while (i < buffer.posn && data[i] != '\n')
 724                                 i++;
 725                 }
 726                 i++;
 727         }
 728
 729         free(buffer.buffer);
 730         repo->got_indices = 1;
 731         return 0;
 732 }
 733
 734 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 735 {
 736         char *url;
 737         struct packed_git *target;
 738         struct packed_git **lst;
 739         FILE *packfile;
 740         char *filename;
 741         char tmpfile[PATH_MAX];
 742         int ret;
 743         long prev_posn = 0;
 744         char range[RANGE_HEADER_SIZE];
 745         struct curl_slist *range_header = NULL;
 746         struct walker_data *data = walker->data;
 747
 748         struct active_request_slot *slot;
 749         struct slot_results results;
 750
 751         if (fetch_indices(walker, repo))
 752                 return -1;
 753         target = find_sha1_pack(sha1, repo->packs);
 754         if (!target)
 755                 return -1;
 756
 757         if (walker->get_verbosely) {
 758                 fprintf(stderr, "Getting pack %s\n",
 759                         sha1_to_hex(target->sha1));
 760                 fprintf(stderr, " which contains %s\n",
 761                         sha1_to_hex(sha1));
 762         }
 763
 764         url = xmalloc(strlen(repo->base) + 65);
 765         sprintf(url, "%s/objects/pack/pack-%s.pack",
 766                 repo->base, sha1_to_hex(target->sha1));
 767
 768         filename = sha1_pack_name(target->sha1);
 769         snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 770         packfile = fopen(tmpfile, "a");
 771         if (!packfile)
 772                 return error("Unable to open local file %s for pack",
 773                              filename);
 774
 775         slot = get_active_slot();
 776         slot->results = &results;
 777         curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
 778         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 779         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 780         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, data->no_pragma_header);
 781         slot->local = packfile;
 782
 783         /* If there is data present from a previous transfer attempt,
 784            resume where it left off */
 785         prev_posn = ftell(packfile);
 786         if (prev_posn>0) {
 787                 if (walker->get_verbosely)
 788                         fprintf(stderr,
 789                                 "Resuming fetch of pack %s at byte %ld\n",
 790                                 sha1_to_hex(target->sha1), prev_posn);
 791                 sprintf(range, "Range: bytes=%ld-", prev_posn);
 792                 range_header = curl_slist_append(range_header, range);
 793                 curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 794         }
 795
 796         if (start_active_slot(slot)) {
 797                 run_active_slot(slot);
 798                 if (results.curl_result != CURLE_OK) {
 799                         fclose(packfile);
 800                         return error("Unable to get pack file %s\n%s", url,
 801                                      curl_errorstr);
 802                 }
 803         } else {
 804                 fclose(packfile);
 805                 return error("Unable to start request");
 806         }
 807
 808         target->pack_size = ftell(packfile);
 809         fclose(packfile);
 810
 811         ret = move_temp_to_file(tmpfile, filename);
 812         if (ret)
 813                 return ret;
 814
 815         lst = &repo->packs;
 816         while (*lst != target)
 817                 lst = &((*lst)->next);
 818         *lst = (*lst)->next;
 819
 820         if (verify_pack(target, 0))
 821                 return -1;
 822         install_packed_git(target);
 823
 824         return 0;
 825 }
 826
 827 static void abort_object_request(struct object_request *obj_req)
 828 {
 829         if (obj_req->local >= 0) {
 830                 close(obj_req->local);
 831                 obj_req->local = -1;
 832         }
 833         unlink(obj_req->tmpfile);
 834         if (obj_req->slot) {
 835                 release_active_slot(obj_req->slot);
 836                 obj_req->slot = NULL;
 837         }
 838         release_object_request(obj_req);
 839 }
 840
 841 static int fetch_object(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 842 {
 843         char *hex = sha1_to_hex(sha1);
 844         int ret = 0;
 845         struct object_request *obj_req = object_queue_head;
 846
 847         while (obj_req != NULL && hashcmp(obj_req->sha1, sha1))
 848                 obj_req = obj_req->next;
 849         if (obj_req == NULL)
 850                 return error("Couldn't find request for %s in the queue", hex);
 851
 852         if (has_sha1_file(obj_req->sha1)) {
 853                 abort_object_request(obj_req);
 854                 return 0;
 855         }
 856
 857 #ifdef USE_CURL_MULTI
 858         while (obj_req->state == WAITING) {
 859                 step_active_slots();
 860         }
 861 #else
 862         start_object_request(walker, obj_req);
 863 #endif
 864
 865         while (obj_req->state == ACTIVE) {
 866                 run_active_slot(obj_req->slot);
 867         }
 868         if (obj_req->local != -1) {
 869                 close(obj_req->local); obj_req->local = -1;
 870         }
 871
 872         if (obj_req->state == ABORTED) {
 873                 ret = error("Request for %s aborted", hex);
 874         } else if (obj_req->curl_result != CURLE_OK &&
 875                    obj_req->http_code != 416) {
 876                 if (missing_target(obj_req))
 877                         ret = -1; /* Be silent, it is probably in a pack. */
 878                 else
 879                         ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 880                                     obj_req->errorstr, obj_req->curl_result,
 881                                     obj_req->http_code, hex);
 882         } else if (obj_req->zret != Z_STREAM_END) {
 883                 walker->corrupt_object_found++;
 884                 ret = error("File %s (%s) corrupt", hex, obj_req->url);
 885         } else if (hashcmp(obj_req->sha1, obj_req->real_sha1)) {
 886                 ret = error("File %s has bad hash", hex);
 887         } else if (obj_req->rename < 0) {
 888                 ret = error("unable to write sha1 filename %s",
 889                             obj_req->filename);
 890         }
 891
 892         release_object_request(obj_req);
 893         return ret;
 894 }
 895
 896 static int fetch(struct walker *walker, unsigned char *sha1)
 897 {
 898         struct walker_data *data = walker->data;
 899         struct alt_base *altbase = data->alt;
 900
 901         if (!fetch_object(walker, altbase, sha1))
 902                 return 0;
 903         while (altbase) {
 904                 if (!fetch_pack(walker, altbase, sha1))
 905                         return 0;
 906                 fetch_alternates(walker, data->alt->base);
 907                 altbase = altbase->next;
 908         }
 909         return error("Unable to find %s under %s", sha1_to_hex(sha1),
 910                      data->alt->base);
 911 }
 912
 913 static inline int needs_quote(int ch)
 914 {
 915         if (((ch >= 'A') && (ch <= 'Z'))
 916                         || ((ch >= 'a') && (ch <= 'z'))
 917                         || ((ch >= '0') && (ch <= '9'))
 918                         || (ch == '/')
 919                         || (ch == '-')
 920                         || (ch == '.'))
 921                 return 0;
 922         return 1;
 923 }
 924
 925 static inline int hex(int v)
 926 {
 927         if (v < 10) return '0' + v;
 928         else return 'A' + v - 10;
 929 }
 930
 931 static char *quote_ref_url(const char *base, const char *ref)
 932 {
 933         const char *cp;
 934         char *dp, *qref;
 935         int len, baselen, ch;
 936
 937         baselen = strlen(base);
 938         len = baselen + 7; /* "/refs/" + NUL */
 939         for (cp = ref; (ch = *cp) != 0; cp++, len++)
 940                 if (needs_quote(ch))
 941                         len += 2; /* extra two hex plus replacement % */
 942         qref = xmalloc(len);
 943         memcpy(qref, base, baselen);
 944         memcpy(qref + baselen, "/refs/", 6);
 945         for (cp = ref, dp = qref + baselen + 6; (ch = *cp) != 0; cp++) {
 946                 if (needs_quote(ch)) {
 947                         *dp++ = '%';
 948                         *dp++ = hex((ch >> 4) & 0xF);
 949                         *dp++ = hex(ch & 0xF);
 950                 }
 951                 else
 952                         *dp++ = ch;
 953         }
 954         *dp = 0;
 955
 956         return qref;
 957 }
 958
 959 static int fetch_ref(struct walker *walker, char *ref, unsigned char *sha1)
 960 {
 961         char *url;
 962         char hex[42];
 963         struct buffer buffer;
 964         struct walker_data *data = walker->data;
 965         const char *base = data->alt->base;
 966         struct active_request_slot *slot;
 967         struct slot_results results;
 968         buffer.size = 41;
 969         buffer.posn = 0;
 970         buffer.buffer = hex;
 971         hex[41] = '\0';
 972
 973         url = quote_ref_url(base, ref);
 974         slot = get_active_slot();
 975         slot->results = &results;
 976         curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 977         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 978         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 979         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 980         if (start_active_slot(slot)) {
 981                 run_active_slot(slot);
 982                 if (results.curl_result != CURLE_OK)
 983                         return error("Couldn't get %s for %s\n%s",
 984                                      url, ref, curl_errorstr);
 985         } else {
 986                 return error("Unable to start request");
 987         }
 988
 989         hex[40] = '\0';
 990         get_sha1_hex(hex, sha1);
 991         return 0;
 992 }
 993
 994 static void cleanup(struct walker *walker)
 995 {
 996         struct walker_data *data = walker->data;
 997         http_cleanup();
 998
 999         curl_slist_free_all(data->no_pragma_header);
1000 }
1001
1002 struct walker *get_http_walker(const char *url)
1003 {
1004         char *s;
1005         struct walker_data *data = xmalloc(sizeof(struct walker_data));
1006         struct walker *walker = xmalloc(sizeof(struct walker));
1007
1008         http_init();
1009
1010         data->no_pragma_header = curl_slist_append(NULL, "Pragma:");
1011
1012         data->alt = xmalloc(sizeof(*data->alt));
1013         data->alt->base = xmalloc(strlen(url) + 1);
1014         strcpy(data->alt->base, url);
1015         for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
1016                 *s = 0;
1017
1018         data->alt->got_indices = 0;
1019         data->alt->packs = NULL;
1020         data->alt->next = NULL;
1021         data->got_alternates = -1;
1022
1023         walker->corrupt_object_found = 0;
1024         walker->fetch = fetch;
1025         walker->fetch_ref = fetch_ref;
1026         walker->prefetch = prefetch;
1027         walker->cleanup = cleanup;
1028         walker->data = data;
1029
1030 #ifdef USE_CURL_MULTI
1031         add_fill_function(walker, (int (*)(void *)) fill_active_slot);
1032 #endif
1033
1034         return walker;
1035 }