Andrew's git - gitweb.git/blob

fbc899408e78c18b5cfeae00ad66927e3ef25053
   1#include "cache.h"
   2#include "object.h"
   3#include "delta.h"
   4#include "pack.h"
   5
   6static int dry_run;
   7static int nr_entries;
   8static const char *base_name;
   9static const char unpack_usage[] = "git-unpack-objects basename";
  10
  11struct pack_entry {
  12        unsigned int offset; /* network byte order */
  13        unsigned char sha1[20];
  14};
  15
  16static void *pack_base;
  17static unsigned long pack_size;
  18static void *index_base;
  19static unsigned long index_size;
  20
  21static struct pack_entry **pack_list;
  22
  23static void *map_file(const char *suffix, unsigned long *sizep)
  24{
  25        static char pathname[PATH_MAX];
  26        unsigned long len;
  27        int fd;
  28        struct stat st;
  29        void *map;
  30
  31        len = snprintf(pathname, PATH_MAX, "%s.%s", base_name, suffix);
  32        if (len >= PATH_MAX)
  33                die("bad pack base-name");
  34        fd = open(pathname, O_RDONLY);
  35        if (fd < 0 || fstat(fd, &st))
  36                die("unable to open '%s'", pathname);
  37        len = st.st_size;
  38        if (!len)
  39                die("bad pack file '%s'", pathname);
  40        map = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  41        if (-1 == (int)(long)map)
  42                die("unable to mmap '%s'", pathname);
  43        close(fd);
  44        *sizep = len;
  45        return map;
  46}
  47
  48static int sort_by_offset(const void *_a, const void *_b)
  49{
  50        struct pack_entry *a = *(struct pack_entry **)_a;
  51        struct pack_entry *b = *(struct pack_entry **)_b;
  52        unsigned int o1, o2;
  53
  54        o1 = ntohl(a->offset);
  55        o2 = ntohl(b->offset);
  56        return o1 < o2 ? -1 : 1;
  57}
  58
  59static int check_index(void)
  60{
  61        unsigned int *array = index_base;
  62        unsigned int nr;
  63        int i;
  64
  65        if (index_size < 4*256 + 20)
  66                return error("index file too small");
  67        nr = 0;
  68        for (i = 0; i < 256; i++) {
  69                unsigned int n = ntohl(array[i]);
  70                if (n < nr)
  71                        return error("non-monotonic index");
  72                nr = n;
  73        }
  74        /*
  75         * Total size:
  76         *  - 256 index entries 4 bytes each
  77         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
  78         *  - 20-byte SHA1 of the packfile
  79         *  - 20-byte SHA1 file checksum
  80         */
  81        if (index_size != 4*256 + nr * 24 + 20 + 20)
  82                return error("wrong index file size");
  83
  84        nr_entries = nr;
  85        pack_list = xmalloc(nr * sizeof(struct pack_entry *));
  86        for (i = 0; i < nr; i++)
  87                pack_list[i] = index_base + 4*256 + i*24;
  88
  89        qsort(pack_list, nr, sizeof(*pack_list), sort_by_offset);
  90
  91        printf("%d entries\n", nr);
  92        return 0;
  93}
  94
  95static int unpack_non_delta_entry(struct pack_entry *entry,
  96                                  enum object_type kind,
  97                                  unsigned char *data,
  98                                  unsigned long size,
  99                                  unsigned long left)
 100{
 101        int st;
 102        z_stream stream;
 103        char *buffer;
 104        unsigned char sha1[20];
 105        char *type;
 106
 107        printf("%s %c %lu\n", sha1_to_hex(entry->sha1), ".CTBGD"[kind], size);
 108        if (dry_run)
 109                return 0;
 110
 111        buffer = xmalloc(size + 1);
 112        buffer[size] = 0;
 113        memset(&stream, 0, sizeof(stream));
 114        stream.next_in = data;
 115        stream.avail_in = left;
 116        stream.next_out = buffer;
 117        stream.avail_out = size;
 118
 119        inflateInit(&stream);
 120        st = inflate(&stream, Z_FINISH);
 121        inflateEnd(&stream);
 122        if ((st != Z_STREAM_END) || stream.total_out != size)
 123                goto err_finish;
 124        switch (kind) {
 125        case OBJ_COMMIT: type = "commit"; break;
 126        case OBJ_TREE:   type = "tree"; break;
 127        case OBJ_BLOB:   type = "blob"; break;
 128        case OBJ_TAG:    type = "tag"; break;
 129        default: goto err_finish;
 130        }
 131        if (write_sha1_file(buffer, size, type, sha1) < 0)
 132                die("failed to write %s (%s)",
 133                    sha1_to_hex(entry->sha1), type);
 134        printf("%s %s\n", sha1_to_hex(sha1), type);
 135        if (memcmp(sha1, entry->sha1, 20))
 136                die("resulting %s have wrong SHA1", type);
 137
 138 finish:
 139        st = 0;
 140        free(buffer);
 141        return st;
 142 err_finish:
 143        st = -1;
 144        goto finish;
 145}
 146
 147static int find_pack_entry(unsigned char *sha1, struct pack_entry **ent)
 148{
 149        int *level1_ofs = index_base;
 150        int hi = ntohl(level1_ofs[*sha1]);
 151        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
 152        void *index = index_base + 4*256;
 153
 154        do {
 155                int mi = (lo + hi) / 2;
 156                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
 157                if (!cmp) {
 158                        *ent = index + 24 * mi;
 159                        return 1;
 160                }
 161                if (cmp > 0)
 162                        hi = mi;
 163                else
 164                        lo = mi+1;
 165        } while (lo < hi);
 166        return 0;
 167}
 168
 169/* forward declaration for a mutually recursive function */
 170static void unpack_entry(struct pack_entry *);
 171
 172static int unpack_delta_entry(struct pack_entry *entry,
 173                              unsigned char *base_sha1,
 174                              unsigned long delta_size,
 175                              unsigned long left)
 176{
 177        void *data, *delta_data, *result, *base;
 178        unsigned long data_size, result_size, base_size;
 179        z_stream stream;
 180        int st;
 181        char type[20];
 182        unsigned char sha1[20];
 183
 184        if (left < 20)
 185                die("truncated pack file");
 186        data = base_sha1 + 20;
 187        data_size = left - 20;
 188        printf("%s D %lu", sha1_to_hex(entry->sha1), delta_size);
 189        printf(" %s\n", sha1_to_hex(base_sha1));
 190
 191        if (dry_run)
 192                return 0;
 193
 194        /* pack+5 is the base sha1, unless we have it, we need to
 195         * unpack it first.
 196         */
 197        if (!has_sha1_file(base_sha1)) {
 198                struct pack_entry *base;
 199                if (!find_pack_entry(base_sha1, &base))
 200                        die("cannot find delta-pack base object");
 201                unpack_entry(base);
 202        }
 203        delta_data = xmalloc(delta_size);
 204
 205        memset(&stream, 0, sizeof(stream));
 206
 207        stream.next_in = data;
 208        stream.avail_in = data_size;
 209        stream.next_out = delta_data;
 210        stream.avail_out = delta_size;
 211
 212        inflateInit(&stream);
 213        st = inflate(&stream, Z_FINISH);
 214        inflateEnd(&stream);
 215        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 216                die("delta data unpack failed");
 217
 218        base = read_sha1_file(base_sha1, type, &base_size);
 219        if (!base)
 220                die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
 221        result = patch_delta(base, base_size,
 222                             delta_data, delta_size,
 223                             &result_size);
 224        if (!result)
 225                die("failed to apply delta");
 226        free(delta_data);
 227
 228        if (write_sha1_file(result, result_size, type, sha1) < 0)
 229                die("failed to write %s (%s)",
 230                    sha1_to_hex(entry->sha1), type);
 231        free(result);
 232        printf("%s %s\n", sha1_to_hex(sha1), type);
 233        if (memcmp(sha1, entry->sha1, 20))
 234                die("resulting %s have wrong SHA1", type);
 235        return 0;
 236}
 237
 238static void unpack_entry(struct pack_entry *entry)
 239{
 240        unsigned long offset, size, left;
 241        unsigned char *pack, c;
 242        int type;
 243
 244        /* Have we done this one already due to deltas based on it? */
 245        if (lookup_object(entry->sha1))
 246                return;
 247
 248        offset = ntohl(entry->offset);
 249        if (offset >= pack_size)
 250                goto bad;
 251
 252        pack = pack_base + offset;
 253        c = *pack++;
 254        offset++;
 255        type = (c >> 4) & 7;
 256        size = (c & 15);
 257        while (c & 0x80) {
 258                if (offset >= pack_size)
 259                        goto bad;
 260                offset++;
 261                c = *pack++;
 262                size = (size << 7) + (c & 0x7f);
 263                
 264        }
 265        left = pack_size - offset;
 266        switch (type) {
 267        case OBJ_COMMIT:
 268        case OBJ_TREE:
 269        case OBJ_BLOB:
 270        case OBJ_TAG:
 271                unpack_non_delta_entry(entry, type, pack, size, left);
 272                return;
 273        case OBJ_DELTA:
 274                unpack_delta_entry(entry, pack, size, left);
 275                return;
 276        }
 277bad:
 278        die("corrupted pack file");
 279}
 280
 281/*
 282 * We unpack from the end, older files first. Now, usually
 283 * there are deltas etc, so we'll not actually write the
 284 * objects in that order, but we might as well try..
 285 */
 286static void unpack_all(void)
 287{
 288        int i = nr_entries;
 289
 290        while (--i >= 0) {
 291                struct pack_entry *entry = pack_list[i];
 292                unpack_entry(entry);
 293        }
 294}
 295
 296int main(int argc, char **argv)
 297{
 298        int i;
 299
 300        for (i = 1 ; i < argc; i++) {
 301                const char *arg = argv[i];
 302
 303                if (*arg == '-') {
 304                        if (!strcmp(arg, "-n")) {
 305                                dry_run = 1;
 306                                continue;
 307                        }
 308                        usage(unpack_usage);
 309                }
 310                if (base_name)
 311                        usage(unpack_usage);
 312                base_name = arg;
 313        }
 314        if (!base_name)
 315                usage(unpack_usage);
 316        index_base = map_file("idx", &index_size);
 317        pack_base = map_file("pack", &pack_size);
 318        if (check_index() < 0)
 319                die("bad index file");
 320        unpack_all();
 321        return 0;
 322}