Andrew's git / gitweb.git / builtin/unpack-objects.c
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builtin / unpack-objects.con commit Eighth batch for 2.17 (d0db9ed)
   1#include "builtin.h"
   2#include "cache.h"
   3#include "config.h"
   4#include "object.h"
   5#include "delta.h"
   6#include "pack.h"
   7#include "blob.h"
   8#include "commit.h"
   9#include "tag.h"
  10#include "tree.h"
  11#include "tree-walk.h"
  12#include "progress.h"
  13#include "decorate.h"
  14#include "fsck.h"
  15
  16static int dry_run, quiet, recover, has_errors, strict;
  17static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict]";
  18
  19/* We always read in 4kB chunks. */
  20static unsigned char buffer[4096];
  21static unsigned int offset, len;
  22static off_t consumed_bytes;
  23static off_t max_input_size;
  24static git_hash_ctx ctx;
  25static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
  26
  27/*
  28 * When running under --strict mode, objects whose reachability are
  29 * suspect are kept in core without getting written in the object
  30 * store.
  31 */
  32struct obj_buffer {
  33        char *buffer;
  34        unsigned long size;
  35};
  36
  37static struct decoration obj_decorate;
  38
  39static struct obj_buffer *lookup_object_buffer(struct object *base)
  40{
  41        return lookup_decoration(&obj_decorate, base);
  42}
  43
  44static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
  45{
  46        struct obj_buffer *obj;
  47        obj = xcalloc(1, sizeof(struct obj_buffer));
  48        obj->buffer = buffer;
  49        obj->size = size;
  50        if (add_decoration(&obj_decorate, object, obj))
  51                die("object %s tried to add buffer twice!", oid_to_hex(&object->oid));
  52}
  53
  54/*
  55 * Make sure at least "min" bytes are available in the buffer, and
  56 * return the pointer to the buffer.
  57 */
  58static void *fill(int min)
  59{
  60        if (min <= len)
  61                return buffer + offset;
  62        if (min > sizeof(buffer))
  63                die("cannot fill %d bytes", min);
  64        if (offset) {
  65                the_hash_algo->update_fn(&ctx, buffer, offset);
  66                memmove(buffer, buffer + offset, len);
  67                offset = 0;
  68        }
  69        do {
  70                ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
  71                if (ret <= 0) {
  72                        if (!ret)
  73                                die("early EOF");
  74                        die_errno("read error on input");
  75                }
  76                len += ret;
  77        } while (len < min);
  78        return buffer;
  79}
  80
  81static void use(int bytes)
  82{
  83        if (bytes > len)
  84                die("used more bytes than were available");
  85        len -= bytes;
  86        offset += bytes;
  87
  88        /* make sure off_t is sufficiently large not to wrap */
  89        if (signed_add_overflows(consumed_bytes, bytes))
  90                die("pack too large for current definition of off_t");
  91        consumed_bytes += bytes;
  92        if (max_input_size && consumed_bytes > max_input_size)
  93                die(_("pack exceeds maximum allowed size"));
  94}
  95
  96static void *get_data(unsigned long size)
  97{
  98        git_zstream stream;
  99        void *buf = xmallocz(size);
 100
 101        memset(&stream, 0, sizeof(stream));
 102
 103        stream.next_out = buf;
 104        stream.avail_out = size;
 105        stream.next_in = fill(1);
 106        stream.avail_in = len;
 107        git_inflate_init(&stream);
 108
 109        for (;;) {
 110                int ret = git_inflate(&stream, 0);
 111                use(len - stream.avail_in);
 112                if (stream.total_out == size && ret == Z_STREAM_END)
 113                        break;
 114                if (ret != Z_OK) {
 115                        error("inflate returned %d", ret);
 116                        FREE_AND_NULL(buf);
 117                        if (!recover)
 118                                exit(1);
 119                        has_errors = 1;
 120                        break;
 121                }
 122                stream.next_in = fill(1);
 123                stream.avail_in = len;
 124        }
 125        git_inflate_end(&stream);
 126        return buf;
 127}
 128
 129struct delta_info {
 130        struct object_id base_oid;
 131        unsigned nr;
 132        off_t base_offset;
 133        unsigned long size;
 134        void *delta;
 135        struct delta_info *next;
 136};
 137
 138static struct delta_info *delta_list;
 139
 140static void add_delta_to_list(unsigned nr, const struct object_id *base_oid,
 141                              off_t base_offset,
 142                              void *delta, unsigned long size)
 143{
 144        struct delta_info *info = xmalloc(sizeof(*info));
 145
 146        oidcpy(&info->base_oid, base_oid);
 147        info->base_offset = base_offset;
 148        info->size = size;
 149        info->delta = delta;
 150        info->nr = nr;
 151        info->next = delta_list;
 152        delta_list = info;
 153}
 154
 155struct obj_info {
 156        off_t offset;
 157        struct object_id oid;
 158        struct object *obj;
 159};
 160
 161#define FLAG_OPEN (1u<<20)
 162#define FLAG_WRITTEN (1u<<21)
 163
 164static struct obj_info *obj_list;
 165static unsigned nr_objects;
 166
 167/*
 168 * Called only from check_object() after it verified this object
 169 * is Ok.
 170 */
 171static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 172{
 173        struct object_id oid;
 174
 175        if (write_object_file(obj_buf->buffer, obj_buf->size,
 176                              type_name(obj->type), &oid) < 0)
 177                die("failed to write object %s", oid_to_hex(&obj->oid));
 178        obj->flags |= FLAG_WRITTEN;
 179}
 180
 181/*
 182 * At the very end of the processing, write_rest() scans the objects
 183 * that have reachability requirements and calls this function.
 184 * Verify its reachability and validity recursively and write it out.
 185 */
 186static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 187{
 188        struct obj_buffer *obj_buf;
 189
 190        if (!obj)
 191                return 1;
 192
 193        if (obj->flags & FLAG_WRITTEN)
 194                return 0;
 195
 196        if (type != OBJ_ANY && obj->type != type)
 197                die("object type mismatch");
 198
 199        if (!(obj->flags & FLAG_OPEN)) {
 200                unsigned long size;
 201                int type = sha1_object_info(obj->oid.hash, &size);
 202                if (type != obj->type || type <= 0)
 203                        die("object of unexpected type");
 204                obj->flags |= FLAG_WRITTEN;
 205                return 0;
 206        }
 207
 208        obj_buf = lookup_object_buffer(obj);
 209        if (!obj_buf)
 210                die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
 211        if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 212                die("Error in object");
 213        fsck_options.walk = check_object;
 214        if (fsck_walk(obj, NULL, &fsck_options))
 215                die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
 216        write_cached_object(obj, obj_buf);
 217        return 0;
 218}
 219
 220static void write_rest(void)
 221{
 222        unsigned i;
 223        for (i = 0; i < nr_objects; i++) {
 224                if (obj_list[i].obj)
 225                        check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 226        }
 227}
 228
 229static void added_object(unsigned nr, enum object_type type,
 230                         void *data, unsigned long size);
 231
 232/*
 233 * Write out nr-th object from the list, now we know the contents
 234 * of it.  Under --strict, this buffers structured objects in-core,
 235 * to be checked at the end.
 236 */
 237static void write_object(unsigned nr, enum object_type type,
 238                         void *buf, unsigned long size)
 239{
 240        if (!strict) {
 241                if (write_object_file(buf, size, type_name(type),
 242                                      &obj_list[nr].oid) < 0)
 243                        die("failed to write object");
 244                added_object(nr, type, buf, size);
 245                free(buf);
 246                obj_list[nr].obj = NULL;
 247        } else if (type == OBJ_BLOB) {
 248                struct blob *blob;
 249                if (write_object_file(buf, size, type_name(type),
 250                                      &obj_list[nr].oid) < 0)
 251                        die("failed to write object");
 252                added_object(nr, type, buf, size);
 253                free(buf);
 254
 255                blob = lookup_blob(&obj_list[nr].oid);
 256                if (blob)
 257                        blob->object.flags |= FLAG_WRITTEN;
 258                else
 259                        die("invalid blob object");
 260                obj_list[nr].obj = NULL;
 261        } else {
 262                struct object *obj;
 263                int eaten;
 264                hash_object_file(buf, size, type_name(type), &obj_list[nr].oid);
 265                added_object(nr, type, buf, size);
 266                obj = parse_object_buffer(&obj_list[nr].oid, type, size, buf,
 267                                          &eaten);
 268                if (!obj)
 269                        die("invalid %s", type_name(type));
 270                add_object_buffer(obj, buf, size);
 271                obj->flags |= FLAG_OPEN;
 272                obj_list[nr].obj = obj;
 273        }
 274}
 275
 276static void resolve_delta(unsigned nr, enum object_type type,
 277                          void *base, unsigned long base_size,
 278                          void *delta, unsigned long delta_size)
 279{
 280        void *result;
 281        unsigned long result_size;
 282
 283        result = patch_delta(base, base_size,
 284                             delta, delta_size,
 285                             &result_size);
 286        if (!result)
 287                die("failed to apply delta");
 288        free(delta);
 289        write_object(nr, type, result, result_size);
 290}
 291
 292/*
 293 * We now know the contents of an object (which is nr-th in the pack);
 294 * resolve all the deltified objects that are based on it.
 295 */
 296static void added_object(unsigned nr, enum object_type type,
 297                         void *data, unsigned long size)
 298{
 299        struct delta_info **p = &delta_list;
 300        struct delta_info *info;
 301
 302        while ((info = *p) != NULL) {
 303                if (!oidcmp(&info->base_oid, &obj_list[nr].oid) ||
 304                    info->base_offset == obj_list[nr].offset) {
 305                        *p = info->next;
 306                        p = &delta_list;
 307                        resolve_delta(info->nr, type, data, size,
 308                                      info->delta, info->size);
 309                        free(info);
 310                        continue;
 311                }
 312                p = &info->next;
 313        }
 314}
 315
 316static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 317                                   unsigned nr)
 318{
 319        void *buf = get_data(size);
 320
 321        if (!dry_run && buf)
 322                write_object(nr, type, buf, size);
 323        else
 324                free(buf);
 325}
 326
 327static int resolve_against_held(unsigned nr, const struct object_id *base,
 328                                void *delta_data, unsigned long delta_size)
 329{
 330        struct object *obj;
 331        struct obj_buffer *obj_buffer;
 332        obj = lookup_object(base->hash);
 333        if (!obj)
 334                return 0;
 335        obj_buffer = lookup_object_buffer(obj);
 336        if (!obj_buffer)
 337                return 0;
 338        resolve_delta(nr, obj->type, obj_buffer->buffer,
 339                      obj_buffer->size, delta_data, delta_size);
 340        return 1;
 341}
 342
 343static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 344                               unsigned nr)
 345{
 346        void *delta_data, *base;
 347        unsigned long base_size;
 348        struct object_id base_oid;
 349
 350        if (type == OBJ_REF_DELTA) {
 351                hashcpy(base_oid.hash, fill(the_hash_algo->rawsz));
 352                use(the_hash_algo->rawsz);
 353                delta_data = get_data(delta_size);
 354                if (dry_run || !delta_data) {
 355                        free(delta_data);
 356                        return;
 357                }
 358                if (has_object_file(&base_oid))
 359                        ; /* Ok we have this one */
 360                else if (resolve_against_held(nr, &base_oid,
 361                                              delta_data, delta_size))
 362                        return; /* we are done */
 363                else {
 364                        /* cannot resolve yet --- queue it */
 365                        oidclr(&obj_list[nr].oid);
 366                        add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
 367                        return;
 368                }
 369        } else {
 370                unsigned base_found = 0;
 371                unsigned char *pack, c;
 372                off_t base_offset;
 373                unsigned lo, mid, hi;
 374
 375                pack = fill(1);
 376                c = *pack;
 377                use(1);
 378                base_offset = c & 127;
 379                while (c & 128) {
 380                        base_offset += 1;
 381                        if (!base_offset || MSB(base_offset, 7))
 382                                die("offset value overflow for delta base object");
 383                        pack = fill(1);
 384                        c = *pack;
 385                        use(1);
 386                        base_offset = (base_offset << 7) + (c & 127);
 387                }
 388                base_offset = obj_list[nr].offset - base_offset;
 389                if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 390                        die("offset value out of bound for delta base object");
 391
 392                delta_data = get_data(delta_size);
 393                if (dry_run || !delta_data) {
 394                        free(delta_data);
 395                        return;
 396                }
 397                lo = 0;
 398                hi = nr;
 399                while (lo < hi) {
 400                        mid = lo + (hi - lo) / 2;
 401                        if (base_offset < obj_list[mid].offset) {
 402                                hi = mid;
 403                        } else if (base_offset > obj_list[mid].offset) {
 404                                lo = mid + 1;
 405                        } else {
 406                                oidcpy(&base_oid, &obj_list[mid].oid);
 407                                base_found = !is_null_oid(&base_oid);
 408                                break;
 409                        }
 410                }
 411                if (!base_found) {
 412                        /*
 413                         * The delta base object is itself a delta that
 414                         * has not been resolved yet.
 415                         */
 416                        oidclr(&obj_list[nr].oid);
 417                        add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
 418                        return;
 419                }
 420        }
 421
 422        if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 423                return;
 424
 425        base = read_sha1_file(base_oid.hash, &type, &base_size);
 426        if (!base) {
 427                error("failed to read delta-pack base object %s",
 428                      oid_to_hex(&base_oid));
 429                if (!recover)
 430                        exit(1);
 431                has_errors = 1;
 432                return;
 433        }
 434        resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 435        free(base);
 436}
 437
 438static void unpack_one(unsigned nr)
 439{
 440        unsigned shift;
 441        unsigned char *pack;
 442        unsigned long size, c;
 443        enum object_type type;
 444
 445        obj_list[nr].offset = consumed_bytes;
 446
 447        pack = fill(1);
 448        c = *pack;
 449        use(1);
 450        type = (c >> 4) & 7;
 451        size = (c & 15);
 452        shift = 4;
 453        while (c & 0x80) {
 454                pack = fill(1);
 455                c = *pack;
 456                use(1);
 457                size += (c & 0x7f) << shift;
 458                shift += 7;
 459        }
 460
 461        switch (type) {
 462        case OBJ_COMMIT:
 463        case OBJ_TREE:
 464        case OBJ_BLOB:
 465        case OBJ_TAG:
 466                unpack_non_delta_entry(type, size, nr);
 467                return;
 468        case OBJ_REF_DELTA:
 469        case OBJ_OFS_DELTA:
 470                unpack_delta_entry(type, size, nr);
 471                return;
 472        default:
 473                error("bad object type %d", type);
 474                has_errors = 1;
 475                if (recover)
 476                        return;
 477                exit(1);
 478        }
 479}
 480
 481static void unpack_all(void)
 482{
 483        int i;
 484        struct progress *progress = NULL;
 485        struct pack_header *hdr = fill(sizeof(struct pack_header));
 486
 487        nr_objects = ntohl(hdr->hdr_entries);
 488
 489        if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 490                die("bad pack file");
 491        if (!pack_version_ok(hdr->hdr_version))
 492                die("unknown pack file version %"PRIu32,
 493                        ntohl(hdr->hdr_version));
 494        use(sizeof(struct pack_header));
 495
 496        if (!quiet)
 497                progress = start_progress(_("Unpacking objects"), nr_objects);
 498        obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 499        for (i = 0; i < nr_objects; i++) {
 500                unpack_one(i);
 501                display_progress(progress, i + 1);
 502        }
 503        stop_progress(&progress);
 504
 505        if (delta_list)
 506                die("unresolved deltas left after unpacking");
 507}
 508
 509int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 510{
 511        int i;
 512        struct object_id oid;
 513
 514        check_replace_refs = 0;
 515
 516        git_config(git_default_config, NULL);
 517
 518        quiet = !isatty(2);
 519
 520        for (i = 1 ; i < argc; i++) {
 521                const char *arg = argv[i];
 522
 523                if (*arg == '-') {
 524                        if (!strcmp(arg, "-n")) {
 525                                dry_run = 1;
 526                                continue;
 527                        }
 528                        if (!strcmp(arg, "-q")) {
 529                                quiet = 1;
 530                                continue;
 531                        }
 532                        if (!strcmp(arg, "-r")) {
 533                                recover = 1;
 534                                continue;
 535                        }
 536                        if (!strcmp(arg, "--strict")) {
 537                                strict = 1;
 538                                continue;
 539                        }
 540                        if (skip_prefix(arg, "--strict=", &arg)) {
 541                                strict = 1;
 542                                fsck_set_msg_types(&fsck_options, arg);
 543                                continue;
 544                        }
 545                        if (starts_with(arg, "--pack_header=")) {
 546                                struct pack_header *hdr;
 547                                char *c;
 548
 549                                hdr = (struct pack_header *)buffer;
 550                                hdr->hdr_signature = htonl(PACK_SIGNATURE);
 551                                hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 552                                if (*c != ',')
 553                                        die("bad %s", arg);
 554                                hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 555                                if (*c)
 556                                        die("bad %s", arg);
 557                                len = sizeof(*hdr);
 558                                continue;
 559                        }
 560                        if (skip_prefix(arg, "--max-input-size=", &arg)) {
 561                                max_input_size = strtoumax(arg, NULL, 10);
 562                                continue;
 563                        }
 564                        usage(unpack_usage);
 565                }
 566
 567                /* We don't take any non-flag arguments now.. Maybe some day */
 568                usage(unpack_usage);
 569        }
 570        the_hash_algo->init_fn(&ctx);
 571        unpack_all();
 572        the_hash_algo->update_fn(&ctx, buffer, offset);
 573        the_hash_algo->final_fn(oid.hash, &ctx);
 574        if (strict)
 575                write_rest();
 576        if (hashcmp(fill(the_hash_algo->rawsz), oid.hash))
 577                die("final sha1 did not match");
 578        use(the_hash_algo->rawsz);
 579
 580        /* Write the last part of the buffer to stdout */
 581        while (len) {
 582                int ret = xwrite(1, buffer + offset, len);
 583                if (ret <= 0)
 584                        break;
 585                len -= ret;
 586                offset += ret;
 587        }
 588
 589        /* All done */
 590        return has_errors;
 591}