Andrew's git - gitweb.git/blob

   1#include "cache.h"
   2#include "object.h"
   3#include "delta.h"
   4#include "pack.h"
   5
   6static int dry_run;
   7static const char unpack_usage[] = "git-unpack-objects < pack-file";
   8
   9/* We always read in 4kB chunks. */
  10static unsigned char buffer[4096];
  11static unsigned long offset, len, eof;
  12static SHA_CTX ctx;
  13
  14/*
  15 * Make sure at least "min" bytes are available in the buffer, and
  16 * return the pointer to the buffer.
  17 */
  18static void * fill(int min)
  19{
  20        if (min <= len)
  21                return buffer + offset;
  22        if (eof)
  23                die("unable to fill input");
  24        if (min > sizeof(buffer))
  25                die("cannot fill %d bytes", min);
  26        if (offset) {
  27                SHA1_Update(&ctx, buffer, offset);
  28                memcpy(buffer, buffer + offset, len);
  29                offset = 0;
  30        }
  31        do {
  32                int ret = read(0, buffer + len, sizeof(buffer) - len);
  33                if (ret <= 0) {
  34                        if (!ret)
  35                                die("early EOF");
  36                        if (errno == EAGAIN || errno == EINTR)
  37                                continue;
  38                        die("read error on input: %s", strerror(errno));
  39                }
  40                len += ret;
  41        } while (len < min);
  42        return buffer;
  43}
  44
  45static void use(int bytes)
  46{
  47        if (bytes > len)
  48                die("used more bytes than were available");
  49        len -= bytes;
  50        offset += bytes;
  51}
  52
  53static void *get_data(unsigned long size)
  54{
  55        z_stream stream;
  56        void *buf = xmalloc(size);
  57
  58        if (!size)
  59                return buf;
  60        memset(&stream, 0, sizeof(stream));
  61
  62        stream.next_out = buf;
  63        stream.avail_out = size;
  64        stream.next_in = fill(1);
  65        stream.avail_in = len;
  66        inflateInit(&stream);
  67
  68        for (;;) {
  69                int ret = inflate(&stream, 0);
  70                use(len - stream.avail_in);
  71                if (stream.total_out == size && ret == Z_STREAM_END)
  72                        break;
  73                if (ret != Z_OK)
  74                        die("inflate returned %d\n", ret);
  75                stream.next_in = fill(1);
  76                stream.avail_in = len;
  77        }
  78        return buf;
  79}
  80
  81struct delta_info {
  82        unsigned char base_sha1[20];
  83        unsigned long size;
  84        void *delta;
  85        struct delta_info *next;
  86};
  87
  88static struct delta_info *delta_list;
  89
  90static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
  91{
  92        struct delta_info *info = xmalloc(sizeof(*info));
  93
  94        memcpy(info->base_sha1, base_sha1, 20);
  95        info->size = size;
  96        info->delta = delta;
  97        info->next = delta_list;
  98        delta_list = info;
  99}
 100
 101static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size);
 102
 103static void write_object(void *buf, unsigned long size, const char *type)
 104{
 105        unsigned char sha1[20];
 106        if (write_sha1_file(buf, size, type, sha1) < 0)
 107                die("failed to write object");
 108        added_object(sha1, type, buf, size);
 109}
 110
 111static int resolve_delta(const char *type,
 112        void *base, unsigned long base_size, 
 113        void *delta, unsigned long delta_size)
 114{
 115        void *result;
 116        unsigned long result_size;
 117
 118        result = patch_delta(base, base_size,
 119                             delta, delta_size,
 120                             &result_size);
 121        if (!result)
 122                die("failed to apply delta");
 123        free(delta);
 124        write_object(result, result_size, type);
 125        free(result);
 126        return 0;
 127}
 128
 129static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size)
 130{
 131        struct delta_info **p = &delta_list;
 132        struct delta_info *info;
 133
 134        while ((info = *p) != NULL) {
 135                if (!memcmp(info->base_sha1, sha1, 20)) {
 136                        *p = info->next;
 137                        p = &delta_list;
 138                        resolve_delta(type, data, size, info->delta, info->size);
 139                        free(info);
 140                        continue;
 141                }
 142                p = &info->next;
 143        }
 144}
 145
 146static int unpack_non_delta_entry(enum object_type kind, unsigned long size)
 147{
 148        void *buf = get_data(size);
 149        const char *type;
 150
 151        switch (kind) {
 152        case OBJ_COMMIT: type = "commit"; break;
 153        case OBJ_TREE:   type = "tree"; break;
 154        case OBJ_BLOB:   type = "blob"; break;
 155        case OBJ_TAG:    type = "tag"; break;
 156        default: die("bad type %d", kind);
 157        }
 158        if (!dry_run)
 159                write_object(buf, size, type);
 160        free(buf);
 161        return 0;
 162}
 163
 164static int unpack_delta_entry(unsigned long delta_size)
 165{
 166        void *delta_data, *base;
 167        unsigned long base_size;
 168        char type[20];
 169        unsigned char base_sha1[20];
 170
 171        memcpy(base_sha1, fill(20), 20);
 172        use(20);
 173
 174        delta_data = get_data(delta_size);
 175        if (dry_run) {
 176                free(delta_data);
 177                return 0;
 178        }
 179
 180        if (!has_sha1_file(base_sha1)) {
 181                add_delta_to_list(base_sha1, delta_data, delta_size);
 182                return 0;
 183        }
 184        base = read_sha1_file(base_sha1, type, &base_size);
 185        if (!base)
 186                die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
 187        return resolve_delta(type, base, base_size, delta_data, delta_size);
 188}
 189
 190static void unpack_one(void)
 191{
 192        unsigned shift;
 193        unsigned char *pack, c;
 194        unsigned long size;
 195        enum object_type type;
 196
 197        pack = fill(1);
 198        c = *pack;
 199        use(1);
 200        type = (c >> 4) & 7;
 201        size = (c & 15);
 202        shift = 4;
 203        while (c & 0x80) {
 204                pack = fill(1);
 205                c = *pack++;
 206                use(1);
 207                size += (c & 0x7f) << shift;
 208                shift += 7;
 209        }
 210        switch (type) {
 211        case OBJ_COMMIT:
 212        case OBJ_TREE:
 213        case OBJ_BLOB:
 214        case OBJ_TAG:
 215                unpack_non_delta_entry(type, size);
 216                return;
 217        case OBJ_DELTA:
 218                unpack_delta_entry(size);
 219                return;
 220        default:
 221                die("bad object type %d", type);
 222        }
 223}
 224
 225/*
 226 * We unpack from the end, older files first. Now, usually
 227 * there are deltas etc, so we'll not actually write the
 228 * objects in that order, but we might as well try..
 229 */
 230static void unpack_all(void)
 231{
 232        int i;
 233        struct pack_header *hdr = fill(sizeof(struct pack_header));
 234        unsigned version = ntohl(hdr->hdr_version);
 235        unsigned nr_objects = ntohl(hdr->hdr_entries);
 236
 237        if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 238                die("bad pack file");
 239        if (version != PACK_VERSION)
 240                die("unable to handle pack file version %d", version);
 241        fprintf(stderr, "Unpacking %d objects\n", nr_objects);
 242
 243        use(sizeof(struct pack_header));
 244        for (i = 0; i < nr_objects; i++)
 245                unpack_one();
 246        if (delta_list)
 247                die("unresolved deltas left after unpacking");
 248}
 249
 250int main(int argc, char **argv)
 251{
 252        int i;
 253        unsigned char sha1[20];
 254
 255        for (i = 1 ; i < argc; i++) {
 256                const char *arg = argv[i];
 257
 258                if (*arg == '-') {
 259                        if (!strcmp(arg, "-n")) {
 260                                dry_run = 1;
 261                                continue;
 262                        }
 263                        usage(unpack_usage);
 264                }
 265
 266                /* We don't take any non-flag arguments now.. Maybe some day */
 267                usage(unpack_usage);
 268        }
 269        SHA1_Init(&ctx);
 270        unpack_all();
 271        SHA1_Update(&ctx, buffer, offset);
 272        SHA1_Final(sha1, &ctx);
 273        if (memcmp(fill(20), sha1, 20))
 274                die("final sha1 did not match");
 275        use(20);
 276
 277        /* Write the last part of the buffer to stdout */
 278        while (len) {
 279                int ret = write(1, buffer + offset, len);
 280                if (!ret)
 281                        break;
 282                if (ret < 0) {
 283                        if (errno == EAGAIN || errno == EINTR)
 284                                continue;
 285                        break;
 286                }
 287                len -= ret;
 288                offset += ret;
 289        }
 290
 291        /* All done */
 292        return 0;
 293}