Andrew's git - gitweb.git/blob - builtin/unpack-objects.c

   1#include "builtin.h"
   2#include "cache.h"
   3#include "object.h"
   4#include "delta.h"
   5#include "pack.h"
   6#include "blob.h"
   7#include "commit.h"
   8#include "tag.h"
   9#include "tree.h"
  10#include "tree-walk.h"
  11#include "progress.h"
  12#include "decorate.h"
  13#include "fsck.h"
  14
  15static int dry_run, quiet, recover, has_errors, strict;
  16static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict] < pack-file";
  17
  18/* We always read in 4kB chunks. */
  19static unsigned char buffer[4096];
  20static unsigned int offset, len;
  21static off_t consumed_bytes;
  22static git_SHA_CTX ctx;
  23
  24/*
  25 * When running under --strict mode, objects whose reachability are
  26 * suspect are kept in core without getting written in the object
  27 * store.
  28 */
  29struct obj_buffer {
  30        char *buffer;
  31        unsigned long size;
  32};
  33
  34static struct decoration obj_decorate;
  35
  36static struct obj_buffer *lookup_object_buffer(struct object *base)
  37{
  38        return lookup_decoration(&obj_decorate, base);
  39}
  40
  41static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
  42{
  43        struct obj_buffer *obj;
  44        obj = xcalloc(1, sizeof(struct obj_buffer));
  45        obj->buffer = buffer;
  46        obj->size = size;
  47        if (add_decoration(&obj_decorate, object, obj))
  48                die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
  49}
  50
  51/*
  52 * Make sure at least "min" bytes are available in the buffer, and
  53 * return the pointer to the buffer.
  54 */
  55static void *fill(int min)
  56{
  57        if (min <= len)
  58                return buffer + offset;
  59        if (min > sizeof(buffer))
  60                die("cannot fill %d bytes", min);
  61        if (offset) {
  62                git_SHA1_Update(&ctx, buffer, offset);
  63                memmove(buffer, buffer + offset, len);
  64                offset = 0;
  65        }
  66        do {
  67                ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
  68                if (ret <= 0) {
  69                        if (!ret)
  70                                die("early EOF");
  71                        die_errno("read error on input");
  72                }
  73                len += ret;
  74        } while (len < min);
  75        return buffer;
  76}
  77
  78static void use(int bytes)
  79{
  80        if (bytes > len)
  81                die("used more bytes than were available");
  82        len -= bytes;
  83        offset += bytes;
  84
  85        /* make sure off_t is sufficiently large not to wrap */
  86        if (signed_add_overflows(consumed_bytes, bytes))
  87                die("pack too large for current definition of off_t");
  88        consumed_bytes += bytes;
  89}
  90
  91static void *get_data(unsigned long size)
  92{
  93        git_zstream stream;
  94        void *buf = xmalloc(size);
  95
  96        memset(&stream, 0, sizeof(stream));
  97
  98        stream.next_out = buf;
  99        stream.avail_out = size;
 100        stream.next_in = fill(1);
 101        stream.avail_in = len;
 102        git_inflate_init(&stream);
 103
 104        for (;;) {
 105                int ret = git_inflate(&stream, 0);
 106                use(len - stream.avail_in);
 107                if (stream.total_out == size && ret == Z_STREAM_END)
 108                        break;
 109                if (ret != Z_OK) {
 110                        error("inflate returned %d", ret);
 111                        free(buf);
 112                        buf = NULL;
 113                        if (!recover)
 114                                exit(1);
 115                        has_errors = 1;
 116                        break;
 117                }
 118                stream.next_in = fill(1);
 119                stream.avail_in = len;
 120        }
 121        git_inflate_end(&stream);
 122        return buf;
 123}
 124
 125struct delta_info {
 126        unsigned char base_sha1[20];
 127        unsigned nr;
 128        off_t base_offset;
 129        unsigned long size;
 130        void *delta;
 131        struct delta_info *next;
 132};
 133
 134static struct delta_info *delta_list;
 135
 136static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
 137                              off_t base_offset,
 138                              void *delta, unsigned long size)
 139{
 140        struct delta_info *info = xmalloc(sizeof(*info));
 141
 142        hashcpy(info->base_sha1, base_sha1);
 143        info->base_offset = base_offset;
 144        info->size = size;
 145        info->delta = delta;
 146        info->nr = nr;
 147        info->next = delta_list;
 148        delta_list = info;
 149}
 150
 151struct obj_info {
 152        off_t offset;
 153        unsigned char sha1[20];
 154        struct object *obj;
 155};
 156
 157#define FLAG_OPEN (1u<<20)
 158#define FLAG_WRITTEN (1u<<21)
 159
 160static struct obj_info *obj_list;
 161static unsigned nr_objects;
 162
 163/*
 164 * Called only from check_object() after it verified this object
 165 * is Ok.
 166 */
 167static void write_cached_object(struct object *obj)
 168{
 169        unsigned char sha1[20];
 170        struct obj_buffer *obj_buf = lookup_object_buffer(obj);
 171        if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
 172                die("failed to write object %s", sha1_to_hex(obj->sha1));
 173        obj->flags |= FLAG_WRITTEN;
 174}
 175
 176/*
 177 * At the very end of the processing, write_rest() scans the objects
 178 * that have reachability requirements and calls this function.
 179 * Verify its reachability and validity recursively and write it out.
 180 */
 181static int check_object(struct object *obj, int type, void *data)
 182{
 183        if (!obj)
 184                return 1;
 185
 186        if (obj->flags & FLAG_WRITTEN)
 187                return 0;
 188
 189        if (type != OBJ_ANY && obj->type != type)
 190                die("object type mismatch");
 191
 192        if (!(obj->flags & FLAG_OPEN)) {
 193                unsigned long size;
 194                int type = sha1_object_info(obj->sha1, &size);
 195                if (type != obj->type || type <= 0)
 196                        die("object of unexpected type");
 197                obj->flags |= FLAG_WRITTEN;
 198                return 0;
 199        }
 200
 201        if (fsck_object(obj, 1, fsck_error_function))
 202                die("Error in object");
 203        if (fsck_walk(obj, check_object, NULL))
 204                die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
 205        write_cached_object(obj);
 206        return 0;
 207}
 208
 209static void write_rest(void)
 210{
 211        unsigned i;
 212        for (i = 0; i < nr_objects; i++) {
 213                if (obj_list[i].obj)
 214                        check_object(obj_list[i].obj, OBJ_ANY, NULL);
 215        }
 216}
 217
 218static void added_object(unsigned nr, enum object_type type,
 219                         void *data, unsigned long size);
 220
 221/*
 222 * Write out nr-th object from the list, now we know the contents
 223 * of it.  Under --strict, this buffers structured objects in-core,
 224 * to be checked at the end.
 225 */
 226static void write_object(unsigned nr, enum object_type type,
 227                         void *buf, unsigned long size)
 228{
 229        if (!strict) {
 230                if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
 231                        die("failed to write object");
 232                added_object(nr, type, buf, size);
 233                free(buf);
 234                obj_list[nr].obj = NULL;
 235        } else if (type == OBJ_BLOB) {
 236                struct blob *blob;
 237                if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
 238                        die("failed to write object");
 239                added_object(nr, type, buf, size);
 240                free(buf);
 241
 242                blob = lookup_blob(obj_list[nr].sha1);
 243                if (blob)
 244                        blob->object.flags |= FLAG_WRITTEN;
 245                else
 246                        die("invalid blob object");
 247                obj_list[nr].obj = NULL;
 248        } else {
 249                struct object *obj;
 250                int eaten;
 251                hash_sha1_file(buf, size, typename(type), obj_list[nr].sha1);
 252                added_object(nr, type, buf, size);
 253                obj = parse_object_buffer(obj_list[nr].sha1, type, size, buf, &eaten);
 254                if (!obj)
 255                        die("invalid %s", typename(type));
 256                add_object_buffer(obj, buf, size);
 257                obj->flags |= FLAG_OPEN;
 258                obj_list[nr].obj = obj;
 259        }
 260}
 261
 262static void resolve_delta(unsigned nr, enum object_type type,
 263                          void *base, unsigned long base_size,
 264                          void *delta, unsigned long delta_size)
 265{
 266        void *result;
 267        unsigned long result_size;
 268
 269        result = patch_delta(base, base_size,
 270                             delta, delta_size,
 271                             &result_size);
 272        if (!result)
 273                die("failed to apply delta");
 274        free(delta);
 275        write_object(nr, type, result, result_size);
 276}
 277
 278/*
 279 * We now know the contents of an object (which is nr-th in the pack);
 280 * resolve all the deltified objects that are based on it.
 281 */
 282static void added_object(unsigned nr, enum object_type type,
 283                         void *data, unsigned long size)
 284{
 285        struct delta_info **p = &delta_list;
 286        struct delta_info *info;
 287
 288        while ((info = *p) != NULL) {
 289                if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
 290                    info->base_offset == obj_list[nr].offset) {
 291                        *p = info->next;
 292                        p = &delta_list;
 293                        resolve_delta(info->nr, type, data, size,
 294                                      info->delta, info->size);
 295                        free(info);
 296                        continue;
 297                }
 298                p = &info->next;
 299        }
 300}
 301
 302static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 303                                   unsigned nr)
 304{
 305        void *buf = get_data(size);
 306
 307        if (!dry_run && buf)
 308                write_object(nr, type, buf, size);
 309        else
 310                free(buf);
 311}
 312
 313static int resolve_against_held(unsigned nr, const unsigned char *base,
 314                                void *delta_data, unsigned long delta_size)
 315{
 316        struct object *obj;
 317        struct obj_buffer *obj_buffer;
 318        obj = lookup_object(base);
 319        if (!obj)
 320                return 0;
 321        obj_buffer = lookup_object_buffer(obj);
 322        if (!obj_buffer)
 323                return 0;
 324        resolve_delta(nr, obj->type, obj_buffer->buffer,
 325                      obj_buffer->size, delta_data, delta_size);
 326        return 1;
 327}
 328
 329static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 330                               unsigned nr)
 331{
 332        void *delta_data, *base;
 333        unsigned long base_size;
 334        unsigned char base_sha1[20];
 335
 336        if (type == OBJ_REF_DELTA) {
 337                hashcpy(base_sha1, fill(20));
 338                use(20);
 339                delta_data = get_data(delta_size);
 340                if (dry_run || !delta_data) {
 341                        free(delta_data);
 342                        return;
 343                }
 344                if (has_sha1_file(base_sha1))
 345                        ; /* Ok we have this one */
 346                else if (resolve_against_held(nr, base_sha1,
 347                                              delta_data, delta_size))
 348                        return; /* we are done */
 349                else {
 350                        /* cannot resolve yet --- queue it */
 351                        hashcpy(obj_list[nr].sha1, null_sha1);
 352                        add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
 353                        return;
 354                }
 355        } else {
 356                unsigned base_found = 0;
 357                unsigned char *pack, c;
 358                off_t base_offset;
 359                unsigned lo, mid, hi;
 360
 361                pack = fill(1);
 362                c = *pack;
 363                use(1);
 364                base_offset = c & 127;
 365                while (c & 128) {
 366                        base_offset += 1;
 367                        if (!base_offset || MSB(base_offset, 7))
 368                                die("offset value overflow for delta base object");
 369                        pack = fill(1);
 370                        c = *pack;
 371                        use(1);
 372                        base_offset = (base_offset << 7) + (c & 127);
 373                }
 374                base_offset = obj_list[nr].offset - base_offset;
 375                if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 376                        die("offset value out of bound for delta base object");
 377
 378                delta_data = get_data(delta_size);
 379                if (dry_run || !delta_data) {
 380                        free(delta_data);
 381                        return;
 382                }
 383                lo = 0;
 384                hi = nr;
 385                while (lo < hi) {
 386                        mid = (lo + hi)/2;
 387                        if (base_offset < obj_list[mid].offset) {
 388                                hi = mid;
 389                        } else if (base_offset > obj_list[mid].offset) {
 390                                lo = mid + 1;
 391                        } else {
 392                                hashcpy(base_sha1, obj_list[mid].sha1);
 393                                base_found = !is_null_sha1(base_sha1);
 394                                break;
 395                        }
 396                }
 397                if (!base_found) {
 398                        /*
 399                         * The delta base object is itself a delta that
 400                         * has not been resolved yet.
 401                         */
 402                        hashcpy(obj_list[nr].sha1, null_sha1);
 403                        add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
 404                        return;
 405                }
 406        }
 407
 408        if (resolve_against_held(nr, base_sha1, delta_data, delta_size))
 409                return;
 410
 411        base = read_sha1_file(base_sha1, &type, &base_size);
 412        if (!base) {
 413                error("failed to read delta-pack base object %s",
 414                      sha1_to_hex(base_sha1));
 415                if (!recover)
 416                        exit(1);
 417                has_errors = 1;
 418                return;
 419        }
 420        resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 421        free(base);
 422}
 423
 424static void unpack_one(unsigned nr)
 425{
 426        unsigned shift;
 427        unsigned char *pack;
 428        unsigned long size, c;
 429        enum object_type type;
 430
 431        obj_list[nr].offset = consumed_bytes;
 432
 433        pack = fill(1);
 434        c = *pack;
 435        use(1);
 436        type = (c >> 4) & 7;
 437        size = (c & 15);
 438        shift = 4;
 439        while (c & 0x80) {
 440                pack = fill(1);
 441                c = *pack;
 442                use(1);
 443                size += (c & 0x7f) << shift;
 444                shift += 7;
 445        }
 446
 447        switch (type) {
 448        case OBJ_COMMIT:
 449        case OBJ_TREE:
 450        case OBJ_BLOB:
 451        case OBJ_TAG:
 452                unpack_non_delta_entry(type, size, nr);
 453                return;
 454        case OBJ_REF_DELTA:
 455        case OBJ_OFS_DELTA:
 456                unpack_delta_entry(type, size, nr);
 457                return;
 458        default:
 459                error("bad object type %d", type);
 460                has_errors = 1;
 461                if (recover)
 462                        return;
 463                exit(1);
 464        }
 465}
 466
 467static void unpack_all(void)
 468{
 469        int i;
 470        struct progress *progress = NULL;
 471        struct pack_header *hdr = fill(sizeof(struct pack_header));
 472
 473        nr_objects = ntohl(hdr->hdr_entries);
 474
 475        if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 476                die("bad pack file");
 477        if (!pack_version_ok(hdr->hdr_version))
 478                die("unknown pack file version %"PRIu32,
 479                        ntohl(hdr->hdr_version));
 480        use(sizeof(struct pack_header));
 481
 482        if (!quiet)
 483                progress = start_progress("Unpacking objects", nr_objects);
 484        obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 485        for (i = 0; i < nr_objects; i++) {
 486                unpack_one(i);
 487                display_progress(progress, i + 1);
 488        }
 489        stop_progress(&progress);
 490
 491        if (delta_list)
 492                die("unresolved deltas left after unpacking");
 493}
 494
 495int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 496{
 497        int i;
 498        unsigned char sha1[20];
 499
 500        read_replace_refs = 0;
 501
 502        git_config(git_default_config, NULL);
 503
 504        quiet = !isatty(2);
 505
 506        for (i = 1 ; i < argc; i++) {
 507                const char *arg = argv[i];
 508
 509                if (*arg == '-') {
 510                        if (!strcmp(arg, "-n")) {
 511                                dry_run = 1;
 512                                continue;
 513                        }
 514                        if (!strcmp(arg, "-q")) {
 515                                quiet = 1;
 516                                continue;
 517                        }
 518                        if (!strcmp(arg, "-r")) {
 519                                recover = 1;
 520                                continue;
 521                        }
 522                        if (!strcmp(arg, "--strict")) {
 523                                strict = 1;
 524                                continue;
 525                        }
 526                        if (!prefixcmp(arg, "--pack_header=")) {
 527                                struct pack_header *hdr;
 528                                char *c;
 529
 530                                hdr = (struct pack_header *)buffer;
 531                                hdr->hdr_signature = htonl(PACK_SIGNATURE);
 532                                hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 533                                if (*c != ',')
 534                                        die("bad %s", arg);
 535                                hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 536                                if (*c)
 537                                        die("bad %s", arg);
 538                                len = sizeof(*hdr);
 539                                continue;
 540                        }
 541                        usage(unpack_usage);
 542                }
 543
 544                /* We don't take any non-flag arguments now.. Maybe some day */
 545                usage(unpack_usage);
 546        }
 547        git_SHA1_Init(&ctx);
 548        unpack_all();
 549        git_SHA1_Update(&ctx, buffer, offset);
 550        git_SHA1_Final(sha1, &ctx);
 551        if (strict)
 552                write_rest();
 553        if (hashcmp(fill(20), sha1))
 554                die("final sha1 did not match");
 555        use(20);
 556
 557        /* Write the last part of the buffer to stdout */
 558        while (len) {
 559                int ret = xwrite(1, buffer + offset, len);
 560                if (ret <= 0)
 561                        break;
 562                len -= ret;
 563                offset += ret;
 564        }
 565
 566        /* All done */
 567        return has_errors;
 568}