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
  13 static int dry_run, quiet, recover, has_errors;
  14 static const char unpack_usage[] = "git-unpack-objects [-n] [-q] [-r] < pack-file";
  15
  16 /* We always read in 4kB chunks. */
  17 static unsigned char buffer[4096];
  18 static unsigned long offset, len;
  19 static 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  */
  25 static 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
  48 static 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
  56 static 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                         error("inflate returned %d\n", ret);
  76                         free(buf);
  77                         buf = NULL;
  78                         if (!recover)
  79                                 exit(1);
  80                         has_errors = 1;
  81                         break;
  82                 }
  83                 stream.next_in = fill(1);
  84                 stream.avail_in = len;
  85         }
  86         inflateEnd(&stream);
  87         return buf;
  88 }
  89
  90 struct delta_info {
  91         unsigned char base_sha1[20];
  92         unsigned long size;
  93         void *delta;
  94         struct delta_info *next;
  95 };
  96
  97 static struct delta_info *delta_list;
  98
  99 static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
 100 {
 101         struct delta_info *info = xmalloc(sizeof(*info));
 102
 103         hashcpy(info->base_sha1, base_sha1);
 104         info->size = size;
 105         info->delta = delta;
 106         info->next = delta_list;
 107         delta_list = info;
 108 }
 109
 110 static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size);
 111
 112 static void write_object(void *buf, unsigned long size, const char *type)
 113 {
 114         unsigned char sha1[20];
 115         if (write_sha1_file(buf, size, type, sha1) < 0)
 116                 die("failed to write object");
 117         added_object(sha1, type, buf, size);
 118 }
 119
 120 static void resolve_delta(const char *type,
 121                           void *base, unsigned long base_size,
 122                           void *delta, unsigned long delta_size)
 123 {
 124         void *result;
 125         unsigned long result_size;
 126
 127         result = patch_delta(base, base_size,
 128                              delta, delta_size,
 129                              &result_size);
 130         if (!result)
 131                 die("failed to apply delta");
 132         free(delta);
 133         write_object(result, result_size, type);
 134         free(result);
 135 }
 136
 137 static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size)
 138 {
 139         struct delta_info **p = &delta_list;
 140         struct delta_info *info;
 141
 142         while ((info = *p) != NULL) {
 143                 if (!hashcmp(info->base_sha1, sha1)) {
 144                         *p = info->next;
 145                         p = &delta_list;
 146                         resolve_delta(type, data, size, info->delta, info->size);
 147                         free(info);
 148                         continue;
 149                 }
 150                 p = &info->next;
 151         }
 152 }
 153
 154 static void unpack_non_delta_entry(enum object_type kind, unsigned long size)
 155 {
 156         void *buf = get_data(size);
 157         const char *type;
 158
 159         switch (kind) {
 160         case OBJ_COMMIT: type = commit_type; break;
 161         case OBJ_TREE:   type = tree_type; break;
 162         case OBJ_BLOB:   type = blob_type; break;
 163         case OBJ_TAG:    type = tag_type; break;
 164         default: die("bad type %d", kind);
 165         }
 166         if (!dry_run && buf)
 167                 write_object(buf, size, type);
 168         free(buf);
 169 }
 170
 171 static void unpack_delta_entry(unsigned long delta_size)
 172 {
 173         void *delta_data, *base;
 174         unsigned long base_size;
 175         char type[20];
 176         unsigned char base_sha1[20];
 177
 178         hashcpy(base_sha1, fill(20));
 179         use(20);
 180
 181         delta_data = get_data(delta_size);
 182         if (dry_run || !delta_data) {
 183                 free(delta_data);
 184                 return;
 185         }
 186
 187         if (!has_sha1_file(base_sha1)) {
 188                 add_delta_to_list(base_sha1, delta_data, delta_size);
 189                 return;
 190         }
 191         base = read_sha1_file(base_sha1, type, &base_size);
 192         if (!base) {
 193                 error("failed to read delta-pack base object %s",
 194                       sha1_to_hex(base_sha1));
 195                 if (!recover)
 196                         exit(1);
 197                 has_errors = 1;
 198                 return;
 199         }
 200         resolve_delta(type, base, base_size, delta_data, delta_size);
 201         free(base);
 202 }
 203
 204 static void unpack_one(unsigned nr, unsigned total)
 205 {
 206         unsigned shift;
 207         unsigned char *pack, c;
 208         unsigned long size;
 209         enum object_type type;
 210
 211         pack = fill(1);
 212         c = *pack;
 213         use(1);
 214         type = (c >> 4) & 7;
 215         size = (c & 15);
 216         shift = 4;
 217         while (c & 0x80) {
 218                 pack = fill(1);
 219                 c = *pack++;
 220                 use(1);
 221                 size += (c & 0x7f) << shift;
 222                 shift += 7;
 223         }
 224         if (!quiet) {
 225                 static unsigned long last_sec;
 226                 static unsigned last_percent;
 227                 struct timeval now;
 228                 unsigned percentage = (nr * 100) / total;
 229
 230                 gettimeofday(&now, NULL);
 231                 if (percentage != last_percent || now.tv_sec != last_sec) {
 232                         last_sec = now.tv_sec;
 233                         last_percent = percentage;
 234                         fprintf(stderr, "%4u%% (%u/%u) done\r", percentage, nr, total);
 235                 }
 236         }
 237         switch (type) {
 238         case OBJ_COMMIT:
 239         case OBJ_TREE:
 240         case OBJ_BLOB:
 241         case OBJ_TAG:
 242                 unpack_non_delta_entry(type, size);
 243                 return;
 244         case OBJ_DELTA:
 245                 unpack_delta_entry(size);
 246                 return;
 247         default:
 248                 error("bad object type %d", type);
 249                 has_errors = 1;
 250                 if (recover)
 251                         return;
 252                 exit(1);
 253         }
 254 }
 255
 256 static void unpack_all(void)
 257 {
 258         int i;
 259         struct pack_header *hdr = fill(sizeof(struct pack_header));
 260         unsigned nr_objects = ntohl(hdr->hdr_entries);
 261
 262         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 263                 die("bad pack file");
 264         if (!pack_version_ok(hdr->hdr_version))
 265                 die("unknown pack file version %d", ntohl(hdr->hdr_version));
 266         fprintf(stderr, "Unpacking %d objects\n", nr_objects);
 267
 268         use(sizeof(struct pack_header));
 269         for (i = 0; i < nr_objects; i++)
 270                 unpack_one(i+1, nr_objects);
 271         if (delta_list)
 272                 die("unresolved deltas left after unpacking");
 273 }
 274
 275 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 276 {
 277         int i;
 278         unsigned char sha1[20];
 279
 280         git_config(git_default_config);
 281
 282         quiet = !isatty(2);
 283
 284         for (i = 1 ; i < argc; i++) {
 285                 const char *arg = argv[i];
 286
 287                 if (*arg == '-') {
 288                         if (!strcmp(arg, "-n")) {
 289                                 dry_run = 1;
 290                                 continue;
 291                         }
 292                         if (!strcmp(arg, "-q")) {
 293                                 quiet = 1;
 294                                 continue;
 295                         }
 296                         if (!strcmp(arg, "-r")) {
 297                                 recover = 1;
 298                                 continue;
 299                         }
 300                         usage(unpack_usage);
 301                 }
 302
 303                 /* We don't take any non-flag arguments now.. Maybe some day */
 304                 usage(unpack_usage);
 305         }
 306         SHA1_Init(&ctx);
 307         unpack_all();
 308         SHA1_Update(&ctx, buffer, offset);
 309         SHA1_Final(sha1, &ctx);
 310         if (hashcmp(fill(20), sha1))
 311                 die("final sha1 did not match");
 312         use(20);
 313
 314         /* Write the last part of the buffer to stdout */
 315         while (len) {
 316                 int ret = xwrite(1, buffer + offset, len);
 317                 if (ret <= 0)
 318                         break;
 319                 len -= ret;
 320                 offset += ret;
 321         }
 322
 323         /* All done */
 324         if (!quiet)
 325                 fprintf(stderr, "\n");
 326         return has_errors;
 327 }