Andrew's git / gitweb.git / http-fetch.c
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http-fetch.con commit Everyday: some examples. (44db136)
   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
  10static int got_alternates = -1;
  11
  12static struct curl_slist *no_pragma_header;
  13
  14struct alt_base
  15{
  16        char *base;
  17        int got_indices;
  18        struct packed_git *packs;
  19        struct alt_base *next;
  20};
  21
  22static struct alt_base *alt = NULL;
  23
  24enum object_request_state {
  25        WAITING,
  26        ABORTED,
  27        ACTIVE,
  28        COMPLETE,
  29};
  30
  31struct 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
  52struct alternates_request {
  53        char *base;
  54        char *url;
  55        struct buffer *buffer;
  56        struct active_request_slot *slot;
  57        int http_specific;
  58};
  59
  60static struct object_request *object_queue_head = NULL;
  61
  62static 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
  90static void fetch_alternates(char *base);
  91
  92static void process_object_response(void *callback_data);
  93
  94static 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
 226static void finish_object_request(struct object_request *obj_req)
 227{
 228        struct stat st;
 229
 230        fchmod(obj_req->local, 0444);
 231        close(obj_req->local); obj_req->local = -1;
 232
 233        if (obj_req->http_code == 416) {
 234                fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
 235        } else if (obj_req->curl_result != CURLE_OK) {
 236                if (stat(obj_req->tmpfile, &st) == 0)
 237                        if (st.st_size == 0)
 238                                unlink(obj_req->tmpfile);
 239                return;
 240        }
 241
 242        inflateEnd(&obj_req->stream);
 243        SHA1_Final(obj_req->real_sha1, &obj_req->c);
 244        if (obj_req->zret != Z_STREAM_END) {
 245                unlink(obj_req->tmpfile);
 246                return;
 247        }
 248        if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
 249                unlink(obj_req->tmpfile);
 250                return;
 251        }
 252        obj_req->rename =
 253                move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 254
 255        if (obj_req->rename == 0)
 256                pull_say("got %s\n", sha1_to_hex(obj_req->sha1));
 257}
 258
 259static void process_object_response(void *callback_data)
 260{
 261        struct object_request *obj_req =
 262                (struct object_request *)callback_data;
 263
 264        obj_req->curl_result = obj_req->slot->curl_result;
 265        obj_req->http_code = obj_req->slot->http_code;
 266        obj_req->slot = NULL;
 267        obj_req->state = COMPLETE;
 268
 269        /* Use alternates if necessary */
 270        if (obj_req->http_code == 404) {
 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
 285static 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
 305void 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
 332void 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
 365static 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
 378        if (has_pack_index(sha1))
 379                return 0;
 380
 381        if (get_verbosely)
 382                fprintf(stderr, "Getting index for pack %s\n", hex);
 383        
 384        url = xmalloc(strlen(repo->base) + 64);
 385        sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
 386        
 387        filename = sha1_pack_index_name(sha1);
 388        snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 389        indexfile = fopen(tmpfile, "a");
 390        if (!indexfile)
 391                return error("Unable to open local file %s for pack index",
 392                             filename);
 393
 394        slot = get_active_slot();
 395        curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
 396        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 397        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 398        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 399        slot->local = indexfile;
 400
 401        /* If there is data present from a previous transfer attempt,
 402           resume where it left off */
 403        prev_posn = ftell(indexfile);
 404        if (prev_posn>0) {
 405                if (get_verbosely)
 406                        fprintf(stderr,
 407                                "Resuming fetch of index for pack %s at byte %ld\n",
 408                                hex, prev_posn);
 409                sprintf(range, "Range: bytes=%ld-", prev_posn);
 410                range_header = curl_slist_append(range_header, range);
 411                curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 412        }
 413
 414        if (start_active_slot(slot)) {
 415                run_active_slot(slot);
 416                if (slot->curl_result != CURLE_OK) {
 417                        fclose(indexfile);
 418                        return error("Unable to get pack index %s\n%s", url,
 419                                     curl_errorstr);
 420                }
 421        } else {
 422                fclose(indexfile);
 423                return error("Unable to start request");
 424        }
 425
 426        fclose(indexfile);
 427
 428        return move_temp_to_file(tmpfile, filename);
 429}
 430
 431static int setup_index(struct alt_base *repo, unsigned char *sha1)
 432{
 433        struct packed_git *new_pack;
 434        if (has_pack_file(sha1))
 435                return 0; // don't list this as something we can get
 436
 437        if (fetch_index(repo, sha1))
 438                return -1;
 439
 440        new_pack = parse_pack_index(sha1);
 441        new_pack->next = repo->packs;
 442        repo->packs = new_pack;
 443        return 0;
 444}
 445
 446static void process_alternates_response(void *callback_data)
 447{
 448        struct alternates_request *alt_req =
 449                (struct alternates_request *)callback_data;
 450        struct active_request_slot *slot = alt_req->slot;
 451        struct alt_base *tail = alt;
 452        char *base = alt_req->base;
 453        static const char null_byte = '\0';
 454        char *data;
 455        int i = 0;
 456
 457        if (alt_req->http_specific) {
 458                if (slot->curl_result != CURLE_OK ||
 459                    !alt_req->buffer->posn) {
 460
 461                        /* Try reusing the slot to get non-http alternates */
 462                        alt_req->http_specific = 0;
 463                        sprintf(alt_req->url, "%s/objects/info/alternates",
 464                                base);
 465                        curl_easy_setopt(slot->curl, CURLOPT_URL,
 466                                         alt_req->url);
 467                        active_requests++;
 468                        slot->in_use = 1;
 469                        if (start_active_slot(slot)) {
 470                                return;
 471                        } else {
 472                                got_alternates = -1;
 473                                slot->in_use = 0;
 474                                return;
 475                        }
 476                }
 477        } else if (slot->curl_result != CURLE_OK) {
 478                if (slot->http_code != 404) {
 479                        got_alternates = -1;
 480                        return;
 481                }
 482        }
 483
 484        fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
 485        alt_req->buffer->posn--;
 486        data = alt_req->buffer->buffer;
 487
 488        while (i < alt_req->buffer->posn) {
 489                int posn = i;
 490                while (posn < alt_req->buffer->posn && data[posn] != '\n')
 491                        posn++;
 492                if (data[posn] == '\n') {
 493                        int okay = 0;
 494                        int serverlen = 0;
 495                        struct alt_base *newalt;
 496                        char *target = NULL;
 497                        if (data[i] == '/') {
 498                                serverlen = strchr(base + 8, '/') - base;
 499                                okay = 1;
 500                        } else if (!memcmp(data + i, "../", 3)) {
 501                                i += 3;
 502                                serverlen = strlen(base);
 503                                while (i + 2 < posn && 
 504                                       !memcmp(data + i, "../", 3)) {
 505                                        do {
 506                                                serverlen--;
 507                                        } while (serverlen &&
 508                                                 base[serverlen - 1] != '/');
 509                                        i += 3;
 510                                }
 511                                // If the server got removed, give up.
 512                                okay = strchr(base, ':') - base + 3 < 
 513                                        serverlen;
 514                        } else if (alt_req->http_specific) {
 515                                char *colon = strchr(data + i, ':');
 516                                char *slash = strchr(data + i, '/');
 517                                if (colon && slash && colon < data + posn &&
 518                                    slash < data + posn && colon < slash) {
 519                                        okay = 1;
 520                                }
 521                        }
 522                        // skip 'objects' at end
 523                        if (okay) {
 524                                target = xmalloc(serverlen + posn - i - 6);
 525                                strncpy(target, base, serverlen);
 526                                strncpy(target + serverlen, data + i,
 527                                        posn - i - 7);
 528                                target[serverlen + posn - i - 7] = '\0';
 529                                if (get_verbosely)
 530                                        fprintf(stderr, 
 531                                                "Also look at %s\n", target);
 532                                newalt = xmalloc(sizeof(*newalt));
 533                                newalt->next = NULL;
 534                                newalt->base = target;
 535                                newalt->got_indices = 0;
 536                                newalt->packs = NULL;
 537                                while (tail->next != NULL)
 538                                        tail = tail->next;
 539                                tail->next = newalt;
 540                        }
 541                }
 542                i = posn + 1;
 543        }
 544
 545        got_alternates = 1;
 546}
 547
 548static void fetch_alternates(char *base)
 549{
 550        struct buffer buffer;
 551        char *url;
 552        char *data;
 553        struct active_request_slot *slot;
 554        static struct alternates_request alt_req;
 555
 556        /* If another request has already started fetching alternates,
 557           wait for them to arrive and return to processing this request's
 558           curl message */
 559#ifdef USE_CURL_MULTI
 560        while (got_alternates == 0) {
 561                step_active_slots();
 562        }
 563#endif
 564
 565        /* Nothing to do if they've already been fetched */
 566        if (got_alternates == 1)
 567                return;
 568
 569        /* Start the fetch */
 570        got_alternates = 0;
 571
 572        data = xmalloc(4096);
 573        buffer.size = 4096;
 574        buffer.posn = 0;
 575        buffer.buffer = data;
 576
 577        if (get_verbosely)
 578                fprintf(stderr, "Getting alternates list for %s\n", base);
 579        
 580        url = xmalloc(strlen(base) + 31);
 581        sprintf(url, "%s/objects/info/http-alternates", base);
 582
 583        /* Use a callback to process the result, since another request
 584           may fail and need to have alternates loaded before continuing */
 585        slot = get_active_slot();
 586        slot->callback_func = process_alternates_response;
 587        slot->callback_data = &alt_req;
 588
 589        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 590        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 591        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 592
 593        alt_req.base = base;
 594        alt_req.url = url;
 595        alt_req.buffer = &buffer;
 596        alt_req.http_specific = 1;
 597        alt_req.slot = slot;
 598
 599        if (start_active_slot(slot))
 600                run_active_slot(slot);
 601        else
 602                got_alternates = -1;
 603
 604        free(data);
 605        free(url);
 606}
 607
 608static int fetch_indices(struct alt_base *repo)
 609{
 610        unsigned char sha1[20];
 611        char *url;
 612        struct buffer buffer;
 613        char *data;
 614        int i = 0;
 615
 616        struct active_request_slot *slot;
 617
 618        if (repo->got_indices)
 619                return 0;
 620
 621        data = xmalloc(4096);
 622        buffer.size = 4096;
 623        buffer.posn = 0;
 624        buffer.buffer = data;
 625
 626        if (get_verbosely)
 627                fprintf(stderr, "Getting pack list for %s\n", repo->base);
 628        
 629        url = xmalloc(strlen(repo->base) + 21);
 630        sprintf(url, "%s/objects/info/packs", repo->base);
 631
 632        slot = get_active_slot();
 633        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 634        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 635        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 636        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 637        if (start_active_slot(slot)) {
 638                run_active_slot(slot);
 639                if (slot->curl_result != CURLE_OK) {
 640                        if (slot->http_code == 404) {
 641                                repo->got_indices = 1;
 642                                free(buffer.buffer);
 643                                return 0;
 644                        } else {
 645                                repo->got_indices = 0;
 646                                free(buffer.buffer);
 647                                return error("%s", curl_errorstr);
 648                        }
 649                }
 650        } else {
 651                repo->got_indices = 0;
 652                free(buffer.buffer);
 653                return error("Unable to start request");
 654        }
 655
 656        data = buffer.buffer;
 657        while (i < buffer.posn) {
 658                switch (data[i]) {
 659                case 'P':
 660                        i++;
 661                        if (i + 52 < buffer.posn &&
 662                            !strncmp(data + i, " pack-", 6) &&
 663                            !strncmp(data + i + 46, ".pack\n", 6)) {
 664                                get_sha1_hex(data + i + 6, sha1);
 665                                setup_index(repo, sha1);
 666                                i += 51;
 667                                break;
 668                        }
 669                default:
 670                        while (data[i] != '\n')
 671                                i++;
 672                }
 673                i++;
 674        }
 675
 676        free(buffer.buffer);
 677        repo->got_indices = 1;
 678        return 0;
 679}
 680
 681static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
 682{
 683        char *url;
 684        struct packed_git *target;
 685        struct packed_git **lst;
 686        FILE *packfile;
 687        char *filename;
 688        char tmpfile[PATH_MAX];
 689        int ret;
 690        long prev_posn = 0;
 691        char range[RANGE_HEADER_SIZE];
 692        struct curl_slist *range_header = NULL;
 693
 694        struct active_request_slot *slot;
 695
 696        if (fetch_indices(repo))
 697                return -1;
 698        target = find_sha1_pack(sha1, repo->packs);
 699        if (!target)
 700                return -1;
 701
 702        if (get_verbosely) {
 703                fprintf(stderr, "Getting pack %s\n",
 704                        sha1_to_hex(target->sha1));
 705                fprintf(stderr, " which contains %s\n",
 706                        sha1_to_hex(sha1));
 707        }
 708
 709        url = xmalloc(strlen(repo->base) + 65);
 710        sprintf(url, "%s/objects/pack/pack-%s.pack",
 711                repo->base, sha1_to_hex(target->sha1));
 712
 713        filename = sha1_pack_name(target->sha1);
 714        snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
 715        packfile = fopen(tmpfile, "a");
 716        if (!packfile)
 717                return error("Unable to open local file %s for pack",
 718                             filename);
 719
 720        slot = get_active_slot();
 721        curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
 722        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
 723        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 724        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
 725        slot->local = packfile;
 726
 727        /* If there is data present from a previous transfer attempt,
 728           resume where it left off */
 729        prev_posn = ftell(packfile);
 730        if (prev_posn>0) {
 731                if (get_verbosely)
 732                        fprintf(stderr,
 733                                "Resuming fetch of pack %s at byte %ld\n",
 734                                sha1_to_hex(target->sha1), prev_posn);
 735                sprintf(range, "Range: bytes=%ld-", prev_posn);
 736                range_header = curl_slist_append(range_header, range);
 737                curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
 738        }
 739
 740        if (start_active_slot(slot)) {
 741                run_active_slot(slot);
 742                if (slot->curl_result != CURLE_OK) {
 743                        fclose(packfile);
 744                        return error("Unable to get pack file %s\n%s", url,
 745                                     curl_errorstr);
 746                }
 747        } else {
 748                fclose(packfile);
 749                return error("Unable to start request");
 750        }
 751
 752        fclose(packfile);
 753
 754        ret = move_temp_to_file(tmpfile, filename);
 755        if (ret)
 756                return ret;
 757
 758        lst = &repo->packs;
 759        while (*lst != target)
 760                lst = &((*lst)->next);
 761        *lst = (*lst)->next;
 762
 763        if (verify_pack(target, 0))
 764                return -1;
 765        install_packed_git(target);
 766
 767        return 0;
 768}
 769
 770static int fetch_object(struct alt_base *repo, unsigned char *sha1)
 771{
 772        char *hex = sha1_to_hex(sha1);
 773        int ret = 0;
 774        struct object_request *obj_req = object_queue_head;
 775
 776        while (obj_req != NULL && memcmp(obj_req->sha1, sha1, 20))
 777                obj_req = obj_req->next;
 778        if (obj_req == NULL)
 779                return error("Couldn't find request for %s in the queue", hex);
 780
 781        if (has_sha1_file(obj_req->sha1)) {
 782                release_object_request(obj_req);
 783                return 0;
 784        }
 785
 786#ifdef USE_CURL_MULTI
 787        while (obj_req->state == WAITING) {
 788                step_active_slots();
 789        }
 790#else
 791        start_object_request(obj_req);
 792#endif
 793
 794        while (obj_req->state == ACTIVE) {
 795                run_active_slot(obj_req->slot);
 796        }
 797        if (obj_req->local != -1) {
 798                close(obj_req->local); obj_req->local = -1;
 799        }
 800
 801        if (obj_req->state == ABORTED) {
 802                ret = error("Request for %s aborted", hex);
 803        } else if (obj_req->curl_result != CURLE_OK &&
 804                   obj_req->http_code != 416) {
 805                if (obj_req->http_code == 404)
 806                        ret = -1; /* Be silent, it is probably in a pack. */
 807                else
 808                        ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 809                                    obj_req->errorstr, obj_req->curl_result,
 810                                    obj_req->http_code, hex);
 811        } else if (obj_req->zret != Z_STREAM_END) {
 812                ret = error("File %s (%s) corrupt\n", hex, obj_req->url);
 813        } else if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
 814                ret = error("File %s has bad hash\n", hex);
 815        } else if (obj_req->rename < 0) {
 816                ret = error("unable to write sha1 filename %s: %s",
 817                            obj_req->filename,
 818                            strerror(obj_req->rename));
 819        }
 820
 821        release_object_request(obj_req);
 822        return ret;
 823}
 824
 825int fetch(unsigned char *sha1)
 826{
 827        struct alt_base *altbase = alt;
 828
 829        if (!fetch_object(altbase, sha1))
 830                return 0;
 831        while (altbase) {
 832                if (!fetch_pack(altbase, sha1))
 833                        return 0;
 834                fetch_alternates(alt->base);
 835                altbase = altbase->next;
 836        }
 837        return error("Unable to find %s under %s\n", sha1_to_hex(sha1), 
 838                     alt->base);
 839}
 840
 841static inline int needs_quote(int ch)
 842{
 843        switch (ch) {
 844        case '/': case '-': case '.':
 845        case 'A'...'Z': case 'a'...'z': case '0'...'9':
 846                return 0;
 847        default:
 848                return 1;
 849        }
 850}
 851
 852static inline int hex(int v)
 853{
 854        if (v < 10) return '0' + v;
 855        else return 'A' + v - 10;
 856}
 857
 858static char *quote_ref_url(const char *base, const char *ref)
 859{
 860        const char *cp;
 861        char *dp, *qref;
 862        int len, baselen, ch;
 863
 864        baselen = strlen(base);
 865        len = baselen + 6; /* "refs/" + NUL */
 866        for (cp = ref; (ch = *cp) != 0; cp++, len++)
 867                if (needs_quote(ch))
 868                        len += 2; /* extra two hex plus replacement % */
 869        qref = xmalloc(len);
 870        memcpy(qref, base, baselen);
 871        memcpy(qref + baselen, "refs/", 5);
 872        for (cp = ref, dp = qref + baselen + 5; (ch = *cp) != 0; cp++) {
 873                if (needs_quote(ch)) {
 874                        *dp++ = '%';
 875                        *dp++ = hex((ch >> 4) & 0xF);
 876                        *dp++ = hex(ch & 0xF);
 877                }
 878                else
 879                        *dp++ = ch;
 880        }
 881        *dp = 0;
 882
 883        return qref;
 884}
 885
 886int fetch_ref(char *ref, unsigned char *sha1)
 887{
 888        char *url;
 889        char hex[42];
 890        struct buffer buffer;
 891        char *base = alt->base;
 892        struct active_request_slot *slot;
 893        buffer.size = 41;
 894        buffer.posn = 0;
 895        buffer.buffer = hex;
 896        hex[41] = '\0';
 897        
 898        url = quote_ref_url(base, ref);
 899        slot = get_active_slot();
 900        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 901        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 902        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
 903        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 904        if (start_active_slot(slot)) {
 905                run_active_slot(slot);
 906                if (slot->curl_result != CURLE_OK)
 907                        return error("Couldn't get %s for %s\n%s",
 908                                     url, ref, curl_errorstr);
 909        } else {
 910                return error("Unable to start request");
 911        }
 912
 913        hex[40] = '\0';
 914        get_sha1_hex(hex, sha1);
 915        return 0;
 916}
 917
 918int main(int argc, char **argv)
 919{
 920        char *commit_id;
 921        char *url;
 922        int arg = 1;
 923        int rc = 0;
 924
 925        setup_git_directory();
 926
 927        while (arg < argc && argv[arg][0] == '-') {
 928                if (argv[arg][1] == 't') {
 929                        get_tree = 1;
 930                } else if (argv[arg][1] == 'c') {
 931                        get_history = 1;
 932                } else if (argv[arg][1] == 'a') {
 933                        get_all = 1;
 934                        get_tree = 1;
 935                        get_history = 1;
 936                } else if (argv[arg][1] == 'v') {
 937                        get_verbosely = 1;
 938                } else if (argv[arg][1] == 'w') {
 939                        write_ref = argv[arg + 1];
 940                        arg++;
 941                } else if (!strcmp(argv[arg], "--recover")) {
 942                        get_recover = 1;
 943                }
 944                arg++;
 945        }
 946        if (argc < arg + 2) {
 947                usage("git-http-fetch [-c] [-t] [-a] [-d] [-v] [--recover] [-w ref] commit-id url");
 948                return 1;
 949        }
 950        commit_id = argv[arg];
 951        url = argv[arg + 1];
 952
 953        http_init();
 954
 955        no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
 956
 957        alt = xmalloc(sizeof(*alt));
 958        alt->base = url;
 959        alt->got_indices = 0;
 960        alt->packs = NULL;
 961        alt->next = NULL;
 962
 963        if (pull(commit_id))
 964                rc = 1;
 965
 966        curl_slist_free_all(no_pragma_header);
 967
 968        http_cleanup();
 969
 970        return rc;
 971}