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
  11#include <sys/time.h>
  12
  13static int dry_run, quiet;
  14static const char unpack_usage[] = "git-unpack-objects [-n] [-q] < pack-file";
  15
  16/* We always read in 4kB chunks. */
  17static unsigned char buffer[4096];
  18static unsigned long offset, len;
  19static SHA_CTX ctx;
  20
  21/*
  22 * Make sure at least "min" bytes are available in the buffer, and
  23 * return the pointer to the buffer.
  24 */
  25static void * fill(int min)
  26{
  27        if (min <= len)
  28                return buffer + offset;
  29        if (min > sizeof(buffer))
  30                die("cannot fill %d bytes", min);
  31        if (offset) {
  32                SHA1_Update(&ctx, buffer, offset);
  33                memcpy(buffer, buffer + offset, len);
  34                offset = 0;
  35        }
  36        do {
  37                int ret = xread(0, buffer + len, sizeof(buffer) - len);
  38                if (ret <= 0) {
  39                        if (!ret)
  40                                die("early EOF");
  41                        die("read error on input: %s", strerror(errno));
  42                }
  43                len += ret;
  44        } while (len < min);
  45        return buffer;
  46}
  47
  48static void use(int bytes)
  49{
  50        if (bytes > len)
  51                die("used more bytes than were available");
  52        len -= bytes;
  53        offset += bytes;
  54}
  55
  56static void *get_data(unsigned long size)
  57{
  58        z_stream stream;
  59        void *buf = xmalloc(size);
  60
  61        memset(&stream, 0, sizeof(stream));
  62
  63        stream.next_out = buf;
  64        stream.avail_out = size;
  65        stream.next_in = fill(1);
  66        stream.avail_in = len;
  67        inflateInit(&stream);
  68
  69        for (;;) {
  70                int ret = inflate(&stream, 0);
  71                use(len - stream.avail_in);
  72                if (stream.total_out == size && ret == Z_STREAM_END)
  73                        break;
  74                if (ret != Z_OK)
  75                        die("inflate returned %d\n", ret);
  76                stream.next_in = fill(1);
  77                stream.avail_in = len;
  78        }
  79        inflateEnd(&stream);
  80        return buf;
  81}
  82
  83struct delta_info {
  84        unsigned char base_sha1[20];
  85        unsigned long size;
  86        void *delta;
  87        struct delta_info *next;
  88};
  89
  90static struct delta_info *delta_list;
  91
  92static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
  93{
  94        struct delta_info *info = xmalloc(sizeof(*info));
  95
  96        hashcpy(info->base_sha1, base_sha1);
  97        info->size = size;
  98        info->delta = delta;
  99        info->next = delta_list;
 100        delta_list = info;
 101}
 102
 103static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size);
 104
 105static void write_object(void *buf, unsigned long size, const char *type)
 106{
 107        unsigned char sha1[20];
 108        if (write_sha1_file(buf, size, type, sha1) < 0)
 109                die("failed to write object");
 110        added_object(sha1, type, buf, size);
 111}
 112
 113static int resolve_delta(const char *type,
 114        void *base, unsigned long base_size,
 115        void *delta, unsigned long delta_size)
 116{
 117        void *result;
 118        unsigned long result_size;
 119
 120        result = patch_delta(base, base_size,
 121                             delta, delta_size,
 122                             &result_size);
 123        if (!result)
 124                die("failed to apply delta");
 125        free(delta);
 126        write_object(result, result_size, type);
 127        free(result);
 128        return 0;
 129}
 130
 131static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size)
 132{
 133        struct delta_info **p = &delta_list;
 134        struct delta_info *info;
 135
 136        while ((info = *p) != NULL) {
 137                if (!hashcmp(info->base_sha1, sha1)) {
 138                        *p = info->next;
 139                        p = &delta_list;
 140                        resolve_delta(type, data, size, info->delta, info->size);
 141                        free(info);
 142                        continue;
 143                }
 144                p = &info->next;
 145        }
 146}
 147
 148static int unpack_non_delta_entry(enum object_type kind, unsigned long size)
 149{
 150        void *buf = get_data(size);
 151        const char *type;
 152
 153        switch (kind) {
 154        case OBJ_COMMIT: type = commit_type; break;
 155        case OBJ_TREE:   type = tree_type; break;
 156        case OBJ_BLOB:   type = blob_type; break;
 157        case OBJ_TAG:    type = tag_type; break;
 158        default: die("bad type %d", kind);
 159        }
 160        if (!dry_run)
 161                write_object(buf, size, type);
 162        free(buf);
 163        return 0;
 164}
 165
 166static int unpack_delta_entry(unsigned long delta_size)
 167{
 168        void *delta_data, *base;
 169        unsigned long base_size;
 170        char type[20];
 171        unsigned char base_sha1[20];
 172        int result;
 173
 174        hashcpy(base_sha1, fill(20));
 175        use(20);
 176
 177        delta_data = get_data(delta_size);
 178        if (dry_run) {
 179                free(delta_data);
 180                return 0;
 181        }
 182
 183        if (!has_sha1_file(base_sha1)) {
 184                add_delta_to_list(base_sha1, delta_data, delta_size);
 185                return 0;
 186        }
 187        base = read_sha1_file(base_sha1, type, &base_size);
 188        if (!base)
 189                die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
 190        result = resolve_delta(type, base, base_size, delta_data, delta_size);
 191        free(base);
 192        return result;
 193}
 194
 195static void unpack_one(unsigned nr, unsigned total)
 196{
 197        unsigned shift;
 198        unsigned char *pack, c;
 199        unsigned long size;
 200        enum object_type type;
 201
 202        pack = fill(1);
 203        c = *pack;
 204        use(1);
 205        type = (c >> 4) & 7;
 206        size = (c & 15);
 207        shift = 4;
 208        while (c & 0x80) {
 209                pack = fill(1);
 210                c = *pack++;
 211                use(1);
 212                size += (c & 0x7f) << shift;
 213                shift += 7;
 214        }
 215        if (!quiet) {
 216                static unsigned long last_sec;
 217                static unsigned last_percent;
 218                struct timeval now;
 219                unsigned percentage = (nr * 100) / total;
 220
 221                gettimeofday(&now, NULL);
 222                if (percentage != last_percent || now.tv_sec != last_sec) {
 223                        last_sec = now.tv_sec;
 224                        last_percent = percentage;
 225                        fprintf(stderr, "%4u%% (%u/%u) done\r", percentage, nr, total);
 226                }
 227        }
 228        switch (type) {
 229        case OBJ_COMMIT:
 230        case OBJ_TREE:
 231        case OBJ_BLOB:
 232        case OBJ_TAG:
 233                unpack_non_delta_entry(type, size);
 234                return;
 235        case OBJ_DELTA:
 236                unpack_delta_entry(size);
 237                return;
 238        default:
 239                die("bad object type %d", type);
 240        }
 241}
 242
 243static void unpack_all(void)
 244{
 245        int i;
 246        struct pack_header *hdr = fill(sizeof(struct pack_header));
 247        unsigned nr_objects = ntohl(hdr->hdr_entries);
 248
 249        if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 250                die("bad pack file");
 251        if (!pack_version_ok(hdr->hdr_version))
 252                die("unknown pack file version %d", ntohl(hdr->hdr_version));
 253        fprintf(stderr, "Unpacking %d objects\n", nr_objects);
 254
 255        use(sizeof(struct pack_header));
 256        for (i = 0; i < nr_objects; i++)
 257                unpack_one(i+1, nr_objects);
 258        if (delta_list)
 259                die("unresolved deltas left after unpacking");
 260}
 261
 262int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 263{
 264        int i;
 265        unsigned char sha1[20];
 266
 267        git_config(git_default_config);
 268
 269        quiet = !isatty(2);
 270
 271        for (i = 1 ; i < argc; i++) {
 272                const char *arg = argv[i];
 273
 274                if (*arg == '-') {
 275                        if (!strcmp(arg, "-n")) {
 276                                dry_run = 1;
 277                                continue;
 278                        }
 279                        if (!strcmp(arg, "-q")) {
 280                                quiet = 1;
 281                                continue;
 282                        }
 283                        usage(unpack_usage);
 284                }
 285
 286                /* We don't take any non-flag arguments now.. Maybe some day */
 287                usage(unpack_usage);
 288        }
 289        SHA1_Init(&ctx);
 290        unpack_all();
 291        SHA1_Update(&ctx, buffer, offset);
 292        SHA1_Final(sha1, &ctx);
 293        if (hashcmp(fill(20), sha1))
 294                die("final sha1 did not match");
 295        use(20);
 296
 297        /* Write the last part of the buffer to stdout */
 298        while (len) {
 299                int ret = xwrite(1, buffer + offset, len);
 300                if (ret <= 0)
 301                        break;
 302                len -= ret;
 303                offset += ret;
 304        }
 305
 306        /* All done */
 307        if (!quiet)
 308                fprintf(stderr, "\n");
 309        return 0;
 310}