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