index-pack.c

   1 #include "cache.h"
   2 #include "delta.h"
   3 #include "pack.h"
   4 #include "csum-file.h"
   5 #include "blob.h"
   6 #include "commit.h"
   7 #include "tag.h"
   8 #include "tree.h"
   9
  10 static const char index_pack_usage[] =
  11 "git-index-pack [-v] [-o <index-file>] [{ ---keep | --keep=<msg> }] { <pack-file> | --stdin [--fix-thin] [<pack-file>] }";
  12
  13 struct object_entry
  14 {
  15         unsigned long offset;
  16         unsigned long size;
  17         unsigned int hdr_size;
  18         enum object_type type;
  19         enum object_type real_type;
  20         unsigned char sha1[20];
  21 };
  22
  23 union delta_base {
  24         unsigned char sha1[20];
  25         unsigned long offset;
  26 };
  27
  28 /*
  29  * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
  30  * to memcmp() only the first 20 bytes.
  31  */
  32 #define UNION_BASE_SZ   20
  33
  34 struct delta_entry
  35 {
  36         union delta_base base;
  37         int obj_no;
  38 };
  39
  40 static struct object_entry *objects;
  41 static struct delta_entry *deltas;
  42 static int nr_objects;
  43 static int nr_deltas;
  44 static int nr_resolved_deltas;
  45
  46 static int from_stdin;
  47 static int verbose;
  48
  49 static volatile sig_atomic_t progress_update;
  50
  51 static void progress_interval(int signum)
  52 {
  53         progress_update = 1;
  54 }
  55
  56 static void setup_progress_signal(void)
  57 {
  58         struct sigaction sa;
  59         struct itimerval v;
  60
  61         memset(&sa, 0, sizeof(sa));
  62         sa.sa_handler = progress_interval;
  63         sigemptyset(&sa.sa_mask);
  64         sa.sa_flags = SA_RESTART;
  65         sigaction(SIGALRM, &sa, NULL);
  66
  67         v.it_interval.tv_sec = 1;
  68         v.it_interval.tv_usec = 0;
  69         v.it_value = v.it_interval;
  70         setitimer(ITIMER_REAL, &v, NULL);
  71
  72 }
  73
  74 static unsigned display_progress(unsigned n, unsigned total, unsigned last_pc)
  75 {
  76         unsigned percent = n * 100 / total;
  77         if (percent != last_pc || progress_update) {
  78                 fprintf(stderr, "%4u%% (%u/%u) done\r", percent, n, total);
  79                 progress_update = 0;
  80         }
  81         return percent;
  82 }
  83
  84 /* We always read in 4kB chunks. */
  85 static unsigned char input_buffer[4096];
  86 static unsigned long input_offset, input_len, consumed_bytes;
  87 static SHA_CTX input_ctx;
  88 static int input_fd, output_fd, pack_fd;
  89
  90 /* Discard current buffer used content. */
  91 static void flush(void)
  92 {
  93         if (input_offset) {
  94                 if (output_fd >= 0)
  95                         write_or_die(output_fd, input_buffer, input_offset);
  96                 SHA1_Update(&input_ctx, input_buffer, input_offset);
  97                 memmove(input_buffer, input_buffer + input_offset, input_len);
  98                 input_offset = 0;
  99         }
 100 }
 101
 102 /*
 103  * Make sure at least "min" bytes are available in the buffer, and
 104  * return the pointer to the buffer.
 105  */
 106 static void *fill(int min)
 107 {
 108         if (min <= input_len)
 109                 return input_buffer + input_offset;
 110         if (min > sizeof(input_buffer))
 111                 die("cannot fill %d bytes", min);
 112         flush();
 113         do {
 114                 int ret = xread(input_fd, input_buffer + input_len,
 115                                 sizeof(input_buffer) - input_len);
 116                 if (ret <= 0) {
 117                         if (!ret)
 118                                 die("early EOF");
 119                         die("read error on input: %s", strerror(errno));
 120                 }
 121                 input_len += ret;
 122         } while (input_len < min);
 123         return input_buffer;
 124 }
 125
 126 static void use(int bytes)
 127 {
 128         if (bytes > input_len)
 129                 die("used more bytes than were available");
 130         input_len -= bytes;
 131         input_offset += bytes;
 132         consumed_bytes += bytes;
 133 }
 134
 135 static const char *open_pack_file(const char *pack_name)
 136 {
 137         if (from_stdin) {
 138                 input_fd = 0;
 139                 if (!pack_name) {
 140                         static char tmpfile[PATH_MAX];
 141                         snprintf(tmpfile, sizeof(tmpfile),
 142                                  "%s/pack_XXXXXX", get_object_directory());
 143                         output_fd = mkstemp(tmpfile);
 144                         pack_name = xstrdup(tmpfile);
 145                 } else
 146                         output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
 147                 if (output_fd < 0)
 148                         die("unable to create %s: %s\n", pack_name, strerror(errno));
 149                 pack_fd = output_fd;
 150         } else {
 151                 input_fd = open(pack_name, O_RDONLY);
 152                 if (input_fd < 0)
 153                         die("cannot open packfile '%s': %s",
 154                             pack_name, strerror(errno));
 155                 output_fd = -1;
 156                 pack_fd = input_fd;
 157         }
 158         SHA1_Init(&input_ctx);
 159         return pack_name;
 160 }
 161
 162 static void parse_pack_header(void)
 163 {
 164         struct pack_header *hdr = fill(sizeof(struct pack_header));
 165
 166         /* Header consistency check */
 167         if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 168                 die("pack signature mismatch");
 169         if (!pack_version_ok(hdr->hdr_version))
 170                 die("pack version %d unsupported", ntohl(hdr->hdr_version));
 171
 172         nr_objects = ntohl(hdr->hdr_entries);
 173         use(sizeof(struct pack_header));
 174 }
 175
 176 static void bad_object(unsigned long offset, const char *format,
 177                        ...) NORETURN __attribute__((format (printf, 2, 3)));
 178
 179 static void bad_object(unsigned long offset, const char *format, ...)
 180 {
 181         va_list params;
 182         char buf[1024];
 183
 184         va_start(params, format);
 185         vsnprintf(buf, sizeof(buf), format, params);
 186         va_end(params);
 187         die("pack has bad object at offset %lu: %s", offset, buf);
 188 }
 189
 190 static void *unpack_entry_data(unsigned long offset, unsigned long size)
 191 {
 192         z_stream stream;
 193         void *buf = xmalloc(size);
 194
 195         memset(&stream, 0, sizeof(stream));
 196         stream.next_out = buf;
 197         stream.avail_out = size;
 198         stream.next_in = fill(1);
 199         stream.avail_in = input_len;
 200         inflateInit(&stream);
 201
 202         for (;;) {
 203                 int ret = inflate(&stream, 0);
 204                 use(input_len - stream.avail_in);
 205                 if (stream.total_out == size && ret == Z_STREAM_END)
 206                         break;
 207                 if (ret != Z_OK)
 208                         bad_object(offset, "inflate returned %d", ret);
 209                 stream.next_in = fill(1);
 210                 stream.avail_in = input_len;
 211         }
 212         inflateEnd(&stream);
 213         return buf;
 214 }
 215
 216 static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
 217 {
 218         unsigned char *p, c;
 219         unsigned long size, base_offset;
 220         unsigned shift;
 221
 222         obj->offset = consumed_bytes;
 223
 224         p = fill(1);
 225         c = *p;
 226         use(1);
 227         obj->type = (c >> 4) & 7;
 228         size = (c & 15);
 229         shift = 4;
 230         while (c & 0x80) {
 231                 p = fill(1);
 232                 c = *p;
 233                 use(1);
 234                 size += (c & 0x7fUL) << shift;
 235                 shift += 7;
 236         }
 237         obj->size = size;
 238
 239         switch (obj->type) {
 240         case OBJ_REF_DELTA:
 241                 hashcpy(delta_base->sha1, fill(20));
 242                 use(20);
 243                 break;
 244         case OBJ_OFS_DELTA:
 245                 memset(delta_base, 0, sizeof(*delta_base));
 246                 p = fill(1);
 247                 c = *p;
 248                 use(1);
 249                 base_offset = c & 127;
 250                 while (c & 128) {
 251                         base_offset += 1;
 252                         if (!base_offset || base_offset & ~(~0UL >> 7))
 253                                 bad_object(obj->offset, "offset value overflow for delta base object");
 254                         p = fill(1);
 255                         c = *p;
 256                         use(1);
 257                         base_offset = (base_offset << 7) + (c & 127);
 258                 }
 259                 delta_base->offset = obj->offset - base_offset;
 260                 if (delta_base->offset >= obj->offset)
 261                         bad_object(obj->offset, "delta base offset is out of bound");
 262                 break;
 263         case OBJ_COMMIT:
 264         case OBJ_TREE:
 265         case OBJ_BLOB:
 266         case OBJ_TAG:
 267                 break;
 268         default:
 269                 bad_object(obj->offset, "unknown object type %d", obj->type);
 270         }
 271         obj->hdr_size = consumed_bytes - obj->offset;
 272
 273         return unpack_entry_data(obj->offset, obj->size);
 274 }
 275
 276 static void *get_data_from_pack(struct object_entry *obj)
 277 {
 278         unsigned long from = obj[0].offset + obj[0].hdr_size;
 279         unsigned long len = obj[1].offset - from;
 280         unsigned long rdy = 0;
 281         unsigned char *src, *data;
 282         z_stream stream;
 283         int st;
 284
 285         src = xmalloc(len);
 286         data = src;
 287         do {
 288                 ssize_t n = pread(pack_fd, data + rdy, len - rdy, from + rdy);
 289                 if (n <= 0)
 290                         die("cannot pread pack file: %s", strerror(errno));
 291                 rdy += n;
 292         } while (rdy < len);
 293         data = xmalloc(obj->size);
 294         memset(&stream, 0, sizeof(stream));
 295         stream.next_out = data;
 296         stream.avail_out = obj->size;
 297         stream.next_in = src;
 298         stream.avail_in = len;
 299         inflateInit(&stream);
 300         while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
 301         inflateEnd(&stream);
 302         if (st != Z_STREAM_END || stream.total_out != obj->size)
 303                 die("serious inflate inconsistency");
 304         free(src);
 305         return data;
 306 }
 307
 308 static int find_delta(const union delta_base *base)
 309 {
 310         int first = 0, last = nr_deltas;
 311
 312         while (first < last) {
 313                 int next = (first + last) / 2;
 314                 struct delta_entry *delta = &deltas[next];
 315                 int cmp;
 316
 317                 cmp = memcmp(base, &delta->base, UNION_BASE_SZ);
 318                 if (!cmp)
 319                         return next;
 320                 if (cmp < 0) {
 321                         last = next;
 322                         continue;
 323                 }
 324                 first = next+1;
 325         }
 326         return -first-1;
 327 }
 328
 329 static int find_delta_children(const union delta_base *base,
 330                                int *first_index, int *last_index)
 331 {
 332         int first = find_delta(base);
 333         int last = first;
 334         int end = nr_deltas - 1;
 335
 336         if (first < 0)
 337                 return -1;
 338         while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
 339                 --first;
 340         while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
 341                 ++last;
 342         *first_index = first;
 343         *last_index = last;
 344         return 0;
 345 }
 346
 347 static void sha1_object(const void *data, unsigned long size,
 348                         enum object_type type, unsigned char *sha1,
 349                         int test_for_collision)
 350 {
 351         SHA_CTX ctx;
 352         char header[50];
 353         int header_size;
 354         const char *type_str;
 355
 356         switch (type) {
 357         case OBJ_COMMIT: type_str = commit_type; break;
 358         case OBJ_TREE:   type_str = tree_type; break;
 359         case OBJ_BLOB:   type_str = blob_type; break;
 360         case OBJ_TAG:    type_str = tag_type; break;
 361         default:
 362                 die("bad type %d", type);
 363         }
 364
 365         header_size = sprintf(header, "%s %lu", type_str, size) + 1;
 366
 367         SHA1_Init(&ctx);
 368         SHA1_Update(&ctx, header, header_size);
 369         SHA1_Update(&ctx, data, size);
 370         SHA1_Final(sha1, &ctx);
 371
 372         if (test_for_collision && has_sha1_file(sha1)) {
 373                 void *has_data;
 374                 enum object_type has_type;
 375                 unsigned long has_size;
 376                 has_data = read_sha1_file(sha1, &has_type, &has_size);
 377                 if (!has_data)
 378                         die("cannot read existing object %s", sha1_to_hex(sha1));
 379                 if (size != has_size || type != has_type ||
 380                     memcmp(data, has_data, size) != 0)
 381                         die("SHA1 COLLISION FOUND WITH %s !", sha1_to_hex(sha1));
 382         }
 383 }
 384
 385 static void resolve_delta(struct object_entry *delta_obj, void *base_data,
 386                           unsigned long base_size, enum object_type type)
 387 {
 388         void *delta_data;
 389         unsigned long delta_size;
 390         void *result;
 391         unsigned long result_size;
 392         union delta_base delta_base;
 393         int j, first, last;
 394
 395         delta_obj->real_type = type;
 396         delta_data = get_data_from_pack(delta_obj);
 397         delta_size = delta_obj->size;
 398         result = patch_delta(base_data, base_size, delta_data, delta_size,
 399                              &result_size);
 400         free(delta_data);
 401         if (!result)
 402                 bad_object(delta_obj->offset, "failed to apply delta");
 403         sha1_object(result, result_size, type, delta_obj->sha1, 1);
 404         nr_resolved_deltas++;
 405
 406         hashcpy(delta_base.sha1, delta_obj->sha1);
 407         if (!find_delta_children(&delta_base, &first, &last)) {
 408                 for (j = first; j <= last; j++) {
 409                         struct object_entry *child = objects + deltas[j].obj_no;
 410                         if (child->real_type == OBJ_REF_DELTA)
 411                                 resolve_delta(child, result, result_size, type);
 412                 }
 413         }
 414
 415         memset(&delta_base, 0, sizeof(delta_base));
 416         delta_base.offset = delta_obj->offset;
 417         if (!find_delta_children(&delta_base, &first, &last)) {
 418                 for (j = first; j <= last; j++) {
 419                         struct object_entry *child = objects + deltas[j].obj_no;
 420                         if (child->real_type == OBJ_OFS_DELTA)
 421                                 resolve_delta(child, result, result_size, type);
 422                 }
 423         }
 424
 425         free(result);
 426 }
 427
 428 static int compare_delta_entry(const void *a, const void *b)
 429 {
 430         const struct delta_entry *delta_a = a;
 431         const struct delta_entry *delta_b = b;
 432         return memcmp(&delta_a->base, &delta_b->base, UNION_BASE_SZ);
 433 }
 434
 435 /* Parse all objects and return the pack content SHA1 hash */
 436 static void parse_pack_objects(unsigned char *sha1)
 437 {
 438         int i, percent = -1;
 439         struct delta_entry *delta = deltas;
 440         void *data;
 441         struct stat st;
 442
 443         /*
 444          * First pass:
 445          * - find locations of all objects;
 446          * - calculate SHA1 of all non-delta objects;
 447          * - remember base (SHA1 or offset) for all deltas.
 448          */
 449         if (verbose)
 450                 fprintf(stderr, "Indexing %d objects.\n", nr_objects);
 451         for (i = 0; i < nr_objects; i++) {
 452                 struct object_entry *obj = &objects[i];
 453                 data = unpack_raw_entry(obj, &delta->base);
 454                 obj->real_type = obj->type;
 455                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
 456                         nr_deltas++;
 457                         delta->obj_no = i;
 458                         delta++;
 459                 } else
 460                         sha1_object(data, obj->size, obj->type, obj->sha1, 1);
 461                 free(data);
 462                 if (verbose)
 463                         percent = display_progress(i+1, nr_objects, percent);
 464         }
 465         objects[i].offset = consumed_bytes;
 466         if (verbose)
 467                 fputc('\n', stderr);
 468
 469         /* Check pack integrity */
 470         flush();
 471         SHA1_Final(sha1, &input_ctx);
 472         if (hashcmp(fill(20), sha1))
 473                 die("pack is corrupted (SHA1 mismatch)");
 474         use(20);
 475
 476         /* If input_fd is a file, we should have reached its end now. */
 477         if (fstat(input_fd, &st))
 478                 die("cannot fstat packfile: %s", strerror(errno));
 479         if (S_ISREG(st.st_mode) &&
 480                         lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
 481                 die("pack has junk at the end");
 482
 483         if (!nr_deltas)
 484                 return;
 485
 486         /* Sort deltas by base SHA1/offset for fast searching */
 487         qsort(deltas, nr_deltas, sizeof(struct delta_entry),
 488               compare_delta_entry);
 489
 490         /*
 491          * Second pass:
 492          * - for all non-delta objects, look if it is used as a base for
 493          *   deltas;
 494          * - if used as a base, uncompress the object and apply all deltas,
 495          *   recursively checking if the resulting object is used as a base
 496          *   for some more deltas.
 497          */
 498         if (verbose)
 499                 fprintf(stderr, "Resolving %d deltas.\n", nr_deltas);
 500         for (i = 0; i < nr_objects; i++) {
 501                 struct object_entry *obj = &objects[i];
 502                 union delta_base base;
 503                 int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;
 504
 505                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
 506                         continue;
 507                 hashcpy(base.sha1, obj->sha1);
 508                 ref = !find_delta_children(&base, &ref_first, &ref_last);
 509                 memset(&base, 0, sizeof(base));
 510                 base.offset = obj->offset;
 511                 ofs = !find_delta_children(&base, &ofs_first, &ofs_last);
 512                 if (!ref && !ofs)
 513                         continue;
 514                 data = get_data_from_pack(obj);
 515                 if (ref)
 516                         for (j = ref_first; j <= ref_last; j++) {
 517                                 struct object_entry *child = objects + deltas[j].obj_no;
 518                                 if (child->real_type == OBJ_REF_DELTA)
 519                                         resolve_delta(child, data,
 520                                                       obj->size, obj->type);
 521                         }
 522                 if (ofs)
 523                         for (j = ofs_first; j <= ofs_last; j++) {
 524                                 struct object_entry *child = objects + deltas[j].obj_no;
 525                                 if (child->real_type == OBJ_OFS_DELTA)
 526                                         resolve_delta(child, data,
 527                                                       obj->size, obj->type);
 528                         }
 529                 free(data);
 530                 if (verbose)
 531                         percent = display_progress(nr_resolved_deltas,
 532                                                    nr_deltas, percent);
 533         }
 534         if (verbose && nr_resolved_deltas == nr_deltas)
 535                 fputc('\n', stderr);
 536 }
 537
 538 static int write_compressed(int fd, void *in, unsigned int size)
 539 {
 540         z_stream stream;
 541         unsigned long maxsize;
 542         void *out;
 543
 544         memset(&stream, 0, sizeof(stream));
 545         deflateInit(&stream, zlib_compression_level);
 546         maxsize = deflateBound(&stream, size);
 547         out = xmalloc(maxsize);
 548
 549         /* Compress it */
 550         stream.next_in = in;
 551         stream.avail_in = size;
 552         stream.next_out = out;
 553         stream.avail_out = maxsize;
 554         while (deflate(&stream, Z_FINISH) == Z_OK);
 555         deflateEnd(&stream);
 556
 557         size = stream.total_out;
 558         write_or_die(fd, out, size);
 559         free(out);
 560         return size;
 561 }
 562
 563 static void append_obj_to_pack(void *buf,
 564                                unsigned long size, enum object_type type)
 565 {
 566         struct object_entry *obj = &objects[nr_objects++];
 567         unsigned char header[10];
 568         unsigned long s = size;
 569         int n = 0;
 570         unsigned char c = (type << 4) | (s & 15);
 571         s >>= 4;
 572         while (s) {
 573                 header[n++] = c | 0x80;
 574                 c = s & 0x7f;
 575                 s >>= 7;
 576         }
 577         header[n++] = c;
 578         write_or_die(output_fd, header, n);
 579         obj[1].offset = obj[0].offset + n;
 580         obj[1].offset += write_compressed(output_fd, buf, size);
 581         sha1_object(buf, size, type, obj->sha1, 0);
 582 }
 583
 584 static int delta_pos_compare(const void *_a, const void *_b)
 585 {
 586         struct delta_entry *a = *(struct delta_entry **)_a;
 587         struct delta_entry *b = *(struct delta_entry **)_b;
 588         return a->obj_no - b->obj_no;
 589 }
 590
 591 static void fix_unresolved_deltas(int nr_unresolved)
 592 {
 593         struct delta_entry **sorted_by_pos;
 594         int i, n = 0, percent = -1;
 595
 596         /*
 597          * Since many unresolved deltas may well be themselves base objects
 598          * for more unresolved deltas, we really want to include the
 599          * smallest number of base objects that would cover as much delta
 600          * as possible by picking the
 601          * trunc deltas first, allowing for other deltas to resolve without
 602          * additional base objects.  Since most base objects are to be found
 603          * before deltas depending on them, a good heuristic is to start
 604          * resolving deltas in the same order as their position in the pack.
 605          */
 606         sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
 607         for (i = 0; i < nr_deltas; i++) {
 608                 if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
 609                         continue;
 610                 sorted_by_pos[n++] = &deltas[i];
 611         }
 612         qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);
 613
 614         for (i = 0; i < n; i++) {
 615                 struct delta_entry *d = sorted_by_pos[i];
 616                 void *data;
 617                 unsigned long size;
 618                 enum object_type type;
 619                 int j, first, last;
 620
 621                 if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
 622                         continue;
 623                 data = read_sha1_file(d->base.sha1, &type, &size);
 624                 if (!data)
 625                         continue;
 626
 627                 find_delta_children(&d->base, &first, &last);
 628                 for (j = first; j <= last; j++) {
 629                         struct object_entry *child = objects + deltas[j].obj_no;
 630                         if (child->real_type == OBJ_REF_DELTA)
 631                                 resolve_delta(child, data, size, type);
 632                 }
 633
 634                 append_obj_to_pack(data, size, type);
 635                 free(data);
 636                 if (verbose)
 637                         percent = display_progress(nr_resolved_deltas,
 638                                                    nr_deltas, percent);
 639         }
 640         free(sorted_by_pos);
 641         if (verbose)
 642                 fputc('\n', stderr);
 643 }
 644
 645 static void readjust_pack_header_and_sha1(unsigned char *sha1)
 646 {
 647         struct pack_header hdr;
 648         SHA_CTX ctx;
 649         int size;
 650
 651         /* Rewrite pack header with updated object number */
 652         if (lseek(output_fd, 0, SEEK_SET) != 0)
 653                 die("cannot seek back: %s", strerror(errno));
 654         if (read_in_full(output_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 655                 die("cannot read pack header back: %s", strerror(errno));
 656         hdr.hdr_entries = htonl(nr_objects);
 657         if (lseek(output_fd, 0, SEEK_SET) != 0)
 658                 die("cannot seek back: %s", strerror(errno));
 659         write_or_die(output_fd, &hdr, sizeof(hdr));
 660         if (lseek(output_fd, 0, SEEK_SET) != 0)
 661                 die("cannot seek back: %s", strerror(errno));
 662
 663         /* Recompute and store the new pack's SHA1 */
 664         SHA1_Init(&ctx);
 665         do {
 666                 unsigned char *buf[4096];
 667                 size = xread(output_fd, buf, sizeof(buf));
 668                 if (size < 0)
 669                         die("cannot read pack data back: %s", strerror(errno));
 670                 SHA1_Update(&ctx, buf, size);
 671         } while (size > 0);
 672         SHA1_Final(sha1, &ctx);
 673         write_or_die(output_fd, sha1, 20);
 674 }
 675
 676 static int sha1_compare(const void *_a, const void *_b)
 677 {
 678         struct object_entry *a = *(struct object_entry **)_a;
 679         struct object_entry *b = *(struct object_entry **)_b;
 680         return hashcmp(a->sha1, b->sha1);
 681 }
 682
 683 /*
 684  * On entry *sha1 contains the pack content SHA1 hash, on exit it is
 685  * the SHA1 hash of sorted object names.
 686  */
 687 static const char *write_index_file(const char *index_name, unsigned char *sha1)
 688 {
 689         struct sha1file *f;
 690         struct object_entry **sorted_by_sha, **list, **last;
 691         unsigned int array[256];
 692         int i, fd;
 693         SHA_CTX ctx;
 694
 695         if (nr_objects) {
 696                 sorted_by_sha =
 697                         xcalloc(nr_objects, sizeof(struct object_entry *));
 698                 list = sorted_by_sha;
 699                 last = sorted_by_sha + nr_objects;
 700                 for (i = 0; i < nr_objects; ++i)
 701                         sorted_by_sha[i] = &objects[i];
 702                 qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
 703                       sha1_compare);
 704
 705         }
 706         else
 707                 sorted_by_sha = list = last = NULL;
 708
 709         if (!index_name) {
 710                 static char tmpfile[PATH_MAX];
 711                 snprintf(tmpfile, sizeof(tmpfile),
 712                          "%s/index_XXXXXX", get_object_directory());
 713                 fd = mkstemp(tmpfile);
 714                 index_name = xstrdup(tmpfile);
 715         } else {
 716                 unlink(index_name);
 717                 fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
 718         }
 719         if (fd < 0)
 720                 die("unable to create %s: %s", index_name, strerror(errno));
 721         f = sha1fd(fd, index_name);
 722
 723         /*
 724          * Write the first-level table (the list is sorted,
 725          * but we use a 256-entry lookup to be able to avoid
 726          * having to do eight extra binary search iterations).
 727          */
 728         for (i = 0; i < 256; i++) {
 729                 struct object_entry **next = list;
 730                 while (next < last) {
 731                         struct object_entry *obj = *next;
 732                         if (obj->sha1[0] != i)
 733                                 break;
 734                         next++;
 735                 }
 736                 array[i] = htonl(next - sorted_by_sha);
 737                 list = next;
 738         }
 739         sha1write(f, array, 256 * sizeof(int));
 740
 741         /* recompute the SHA1 hash of sorted object names.
 742          * currently pack-objects does not do this, but that
 743          * can be fixed.
 744          */
 745         SHA1_Init(&ctx);
 746         /*
 747          * Write the actual SHA1 entries..
 748          */
 749         list = sorted_by_sha;
 750         for (i = 0; i < nr_objects; i++) {
 751                 struct object_entry *obj = *list++;
 752                 unsigned int offset = htonl(obj->offset);
 753                 sha1write(f, &offset, 4);
 754                 sha1write(f, obj->sha1, 20);
 755                 SHA1_Update(&ctx, obj->sha1, 20);
 756         }
 757         sha1write(f, sha1, 20);
 758         sha1close(f, NULL, 1);
 759         free(sorted_by_sha);
 760         SHA1_Final(sha1, &ctx);
 761         return index_name;
 762 }
 763
 764 static void final(const char *final_pack_name, const char *curr_pack_name,
 765                   const char *final_index_name, const char *curr_index_name,
 766                   const char *keep_name, const char *keep_msg,
 767                   unsigned char *sha1)
 768 {
 769         const char *report = "pack";
 770         char name[PATH_MAX];
 771         int err;
 772
 773         if (!from_stdin) {
 774                 close(input_fd);
 775         } else {
 776                 err = close(output_fd);
 777                 if (err)
 778                         die("error while closing pack file: %s", strerror(errno));
 779                 chmod(curr_pack_name, 0444);
 780         }
 781
 782         if (keep_msg) {
 783                 int keep_fd, keep_msg_len = strlen(keep_msg);
 784                 if (!keep_name) {
 785                         snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
 786                                  get_object_directory(), sha1_to_hex(sha1));
 787                         keep_name = name;
 788                 }
 789                 keep_fd = open(keep_name, O_RDWR|O_CREAT|O_EXCL, 0600);
 790                 if (keep_fd < 0) {
 791                         if (errno != EEXIST)
 792                                 die("cannot write keep file");
 793                 } else {
 794                         if (keep_msg_len > 0) {
 795                                 write_or_die(keep_fd, keep_msg, keep_msg_len);
 796                                 write_or_die(keep_fd, "\n", 1);
 797                         }
 798                         close(keep_fd);
 799                         report = "keep";
 800                 }
 801         }
 802
 803         if (final_pack_name != curr_pack_name) {
 804                 if (!final_pack_name) {
 805                         snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
 806                                  get_object_directory(), sha1_to_hex(sha1));
 807                         final_pack_name = name;
 808                 }
 809                 if (move_temp_to_file(curr_pack_name, final_pack_name))
 810                         die("cannot store pack file");
 811         }
 812
 813         chmod(curr_index_name, 0444);
 814         if (final_index_name != curr_index_name) {
 815                 if (!final_index_name) {
 816                         snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
 817                                  get_object_directory(), sha1_to_hex(sha1));
 818                         final_index_name = name;
 819                 }
 820                 if (move_temp_to_file(curr_index_name, final_index_name))
 821                         die("cannot store index file");
 822         }
 823
 824         if (!from_stdin) {
 825                 printf("%s\n", sha1_to_hex(sha1));
 826         } else {
 827                 char buf[48];
 828                 int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
 829                                    report, sha1_to_hex(sha1));
 830                 write_or_die(1, buf, len);
 831
 832                 /*
 833                  * Let's just mimic git-unpack-objects here and write
 834                  * the last part of the input buffer to stdout.
 835                  */
 836                 while (input_len) {
 837                         err = xwrite(1, input_buffer + input_offset, input_len);
 838                         if (err <= 0)
 839                                 break;
 840                         input_len -= err;
 841                         input_offset += err;
 842                 }
 843         }
 844 }
 845
 846 int main(int argc, char **argv)
 847 {
 848         int i, fix_thin_pack = 0;
 849         const char *curr_pack, *pack_name = NULL;
 850         const char *curr_index, *index_name = NULL;
 851         const char *keep_name = NULL, *keep_msg = NULL;
 852         char *index_name_buf = NULL, *keep_name_buf = NULL;
 853         unsigned char sha1[20];
 854
 855         for (i = 1; i < argc; i++) {
 856                 const char *arg = argv[i];
 857
 858                 if (*arg == '-') {
 859                         if (!strcmp(arg, "--stdin")) {
 860                                 from_stdin = 1;
 861                         } else if (!strcmp(arg, "--fix-thin")) {
 862                                 fix_thin_pack = 1;
 863                         } else if (!strcmp(arg, "--keep")) {
 864                                 keep_msg = "";
 865                         } else if (!prefixcmp(arg, "--keep=")) {
 866                                 keep_msg = arg + 7;
 867                         } else if (!prefixcmp(arg, "--pack_header=")) {
 868                                 struct pack_header *hdr;
 869                                 char *c;
 870
 871                                 hdr = (struct pack_header *)input_buffer;
 872                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 873                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 874                                 if (*c != ',')
 875                                         die("bad %s", arg);
 876                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 877                                 if (*c)
 878                                         die("bad %s", arg);
 879                                 input_len = sizeof(*hdr);
 880                         } else if (!strcmp(arg, "-v")) {
 881                                 verbose = 1;
 882                         } else if (!strcmp(arg, "-o")) {
 883                                 if (index_name || (i+1) >= argc)
 884                                         usage(index_pack_usage);
 885                                 index_name = argv[++i];
 886                         } else
 887                                 usage(index_pack_usage);
 888                         continue;
 889                 }
 890
 891                 if (pack_name)
 892                         usage(index_pack_usage);
 893                 pack_name = arg;
 894         }
 895
 896         if (!pack_name && !from_stdin)
 897                 usage(index_pack_usage);
 898         if (fix_thin_pack && !from_stdin)
 899                 die("--fix-thin cannot be used without --stdin");
 900         if (!index_name && pack_name) {
 901                 int len = strlen(pack_name);
 902                 if (!has_extension(pack_name, ".pack"))
 903                         die("packfile name '%s' does not end with '.pack'",
 904                             pack_name);
 905                 index_name_buf = xmalloc(len);
 906                 memcpy(index_name_buf, pack_name, len - 5);
 907                 strcpy(index_name_buf + len - 5, ".idx");
 908                 index_name = index_name_buf;
 909         }
 910         if (keep_msg && !keep_name && pack_name) {
 911                 int len = strlen(pack_name);
 912                 if (!has_extension(pack_name, ".pack"))
 913                         die("packfile name '%s' does not end with '.pack'",
 914                             pack_name);
 915                 keep_name_buf = xmalloc(len);
 916                 memcpy(keep_name_buf, pack_name, len - 5);
 917                 strcpy(keep_name_buf + len - 5, ".keep");
 918                 keep_name = keep_name_buf;
 919         }
 920
 921         curr_pack = open_pack_file(pack_name);
 922         parse_pack_header();
 923         objects = xmalloc((nr_objects + 1) * sizeof(struct object_entry));
 924         deltas = xmalloc(nr_objects * sizeof(struct delta_entry));
 925         if (verbose)
 926                 setup_progress_signal();
 927         parse_pack_objects(sha1);
 928         if (nr_deltas != nr_resolved_deltas) {
 929                 if (fix_thin_pack) {
 930                         int nr_unresolved = nr_deltas - nr_resolved_deltas;
 931                         int nr_objects_initial = nr_objects;
 932                         if (nr_unresolved <= 0)
 933                                 die("confusion beyond insanity");
 934                         objects = xrealloc(objects,
 935                                            (nr_objects + nr_unresolved + 1)
 936                                            * sizeof(*objects));
 937                         fix_unresolved_deltas(nr_unresolved);
 938                         if (verbose)
 939                                 fprintf(stderr, "%d objects were added to complete this thin pack.\n",
 940                                         nr_objects - nr_objects_initial);
 941                         readjust_pack_header_and_sha1(sha1);
 942                 }
 943                 if (nr_deltas != nr_resolved_deltas)
 944                         die("pack has %d unresolved deltas",
 945                             nr_deltas - nr_resolved_deltas);
 946         } else {
 947                 /* Flush remaining pack final 20-byte SHA1. */
 948                 flush();
 949         }
 950         free(deltas);
 951         curr_index = write_index_file(index_name, sha1);
 952         final(pack_name, curr_pack,
 953                 index_name, curr_index,
 954                 keep_name, keep_msg,
 955                 sha1);
 956         free(objects);
 957         free(index_name_buf);
 958         free(keep_name_buf);
 959
 960         return 0;
 961 }