server-info.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "rev-cache.h"
   7
   8 /* refs */
   9 static FILE *info_ref_fp;
  10 static unsigned long info_ref_time;
  11 static int info_ref_is_stale = 0;
  12
  13 static int stat_ref(const char *path, const unsigned char *sha1)
  14 {
  15         struct stat st;
  16         if (!stat(path, &st) && info_ref_time < st.st_mtime)
  17                 info_ref_is_stale = 1;
  18         return 0;
  19 }
  20
  21 static int add_info_ref(const char *path, const unsigned char *sha1)
  22 {
  23         fprintf(info_ref_fp, "%s        %s\n", sha1_to_hex(sha1), path);
  24         return 0;
  25 }
  26
  27 static int update_info_refs(int force)
  28 {
  29         struct stat st;
  30         char *path0 = strdup(git_path("info/refs"));
  31         int len = strlen(path0);
  32         char *path1 = xmalloc(len + 2);
  33
  34         strcpy(path1, path0);
  35         strcpy(path1 + len, "+");
  36
  37         if (!force) {
  38                 if (stat(path0, &st)) {
  39                         if (errno == ENOENT)
  40                                 info_ref_is_stale = 1;
  41                         else
  42                                 return error("cannot stat %s", path0);
  43                 }
  44                 else {
  45                         info_ref_time = st.st_mtime;
  46                         for_each_ref(stat_ref);
  47                 }
  48                 if (!info_ref_is_stale)
  49                         return 0;
  50         }
  51
  52         safe_create_leading_directories(path0);
  53         info_ref_fp = fopen(path1, "w");
  54         if (!info_ref_fp)
  55                 return error("unable to update %s", path0);
  56         for_each_ref(add_info_ref);
  57         fclose(info_ref_fp);
  58         rename(path1, path0);
  59         free(path0);
  60         free(path1);
  61         return 0;
  62 }
  63
  64 /* packs */
  65 struct pack_info {
  66         unsigned long latest;
  67         struct packed_git *p;
  68         int old_num;
  69         int new_num;
  70         int nr_alloc;
  71         int nr_heads;
  72         unsigned char (*head)[20];
  73         char dep[0]; /* more */
  74 } **info;
  75 static int num_pack;
  76 static const char *objdir;
  77 static int objdirlen;
  78
  79 static struct object *parse_object_cheap(const unsigned char *sha1)
  80 {
  81         struct object *o;
  82
  83         if ((o = parse_object(sha1)) == NULL)
  84                 return NULL;
  85         if (o->type == commit_type) {
  86                 struct commit *commit = (struct commit *)o;
  87                 free(commit->buffer);
  88                 commit->buffer = NULL;
  89         }
  90         return o;
  91 }
  92
  93 static struct pack_info *find_pack_by_name(const char *name)
  94 {
  95         int i;
  96         for (i = 0; i < num_pack; i++) {
  97                 struct packed_git *p = info[i]->p;
  98                 /* skip "/pack/" after ".git/objects" */
  99                 if (!strcmp(p->pack_name + objdirlen + 6, name))
 100                         return info[i];
 101         }
 102         return NULL;
 103 }
 104
 105 static struct pack_info *find_pack_by_old_num(int old_num)
 106 {
 107         int i;
 108         for (i = 0; i < num_pack; i++)
 109                 if (info[i]->old_num == old_num)
 110                         return info[i];
 111         return NULL;
 112 }
 113
 114 static int add_head_def(struct pack_info *this, unsigned char *sha1)
 115 {
 116         if (this->nr_alloc <= this->nr_heads) {
 117                 this->nr_alloc = alloc_nr(this->nr_alloc);
 118                 this->head = xrealloc(this->head, this->nr_alloc * 20);
 119         }
 120         memcpy(this->head[this->nr_heads++], sha1, 20);
 121         return 0;
 122 }
 123
 124 /* Returns non-zero when we detect that the info in the
 125  * old file is useless.
 126  */
 127 static int parse_pack_def(const char *line, int old_cnt)
 128 {
 129         struct pack_info *i = find_pack_by_name(line + 2);
 130         if (i) {
 131                 i->old_num = old_cnt;
 132                 return 0;
 133         }
 134         else {
 135                 /* The file describes a pack that is no longer here;
 136                  * dependencies between packs needs to be recalculated.
 137                  */
 138                 return 1;
 139         }
 140 }
 141
 142 /* Returns non-zero when we detect that the info in the
 143  * old file is useless.
 144  */
 145 static int parse_depend_def(char *line)
 146 {
 147         unsigned long num;
 148         char *cp, *ep;
 149         struct pack_info *this, *that;
 150
 151         cp = line + 2;
 152         num = strtoul(cp, &ep, 10);
 153         if (ep == cp)
 154                 return error("invalid input %s", line);
 155         this = find_pack_by_old_num(num);
 156         if (!this)
 157                 return 0;
 158         while (ep && *(cp = ep)) {
 159                 num = strtoul(cp, &ep, 10);
 160                 if (ep == cp)
 161                         break;
 162                 that = find_pack_by_old_num(num);
 163                 if (!that)
 164                         /* The pack this one depends on does not
 165                          * exist; this should not happen because
 166                          * we write out the list of packs first and
 167                          * then dependency information, but it means
 168                          * the file is useless anyway.
 169                          */
 170                         return 1;
 171                 this->dep[that->new_num] = 1;
 172         }
 173         return 0;
 174 }
 175
 176 /* Returns non-zero when we detect that the info in the
 177  * old file is useless.
 178  */
 179 static int parse_head_def(char *line)
 180 {
 181         unsigned char sha1[20];
 182         unsigned long num;
 183         char *cp, *ep;
 184         struct pack_info *this;
 185         struct object *o;
 186
 187         cp = line + 2;
 188         num = strtoul(cp, &ep, 10);
 189         if (ep == cp || *ep++ != ' ')
 190                 return error("invalid input ix %s", line);
 191         this = find_pack_by_old_num(num);
 192         if (!this)
 193                 return 1; /* You know the drill. */
 194         if (get_sha1_hex(ep, sha1) || ep[40] != ' ')
 195                 return error("invalid input sha1 %s (%s)", line, ep);
 196         if ((o = parse_object_cheap(sha1)) == NULL)
 197                 return error("no such object: %s", line);
 198         return add_head_def(this, sha1);
 199 }
 200
 201 /* Returns non-zero when we detect that the info in the
 202  * old file is useless.
 203  */
 204 static int read_pack_info_file(const char *infofile)
 205 {
 206         FILE *fp;
 207         char line[1000];
 208         int old_cnt = 0;
 209
 210         fp = fopen(infofile, "r");
 211         if (!fp)
 212                 return 1; /* nonexisting is not an error. */
 213
 214         while (fgets(line, sizeof(line), fp)) {
 215                 int len = strlen(line);
 216                 if (line[len-1] == '\n')
 217                         line[len-1] = 0;
 218
 219                 switch (line[0]) {
 220                 case 'P': /* P name */
 221                         if (parse_pack_def(line, old_cnt++))
 222                                 goto out_stale;
 223                         break;
 224                 case 'D': /* D ix dep-ix1 dep-ix2... */
 225                         if (parse_depend_def(line))
 226                                 goto out_stale;
 227                         break;
 228                 case 'T': /* T ix sha1 type */
 229                         if (parse_head_def(line))
 230                                 goto out_stale;
 231                         break;
 232                 default:
 233                         error("unrecognized: %s", line);
 234                         break;
 235                 }
 236         }
 237         fclose(fp);
 238         return 0;
 239  out_stale:
 240         fclose(fp);
 241         return 1;
 242 }
 243
 244 /* We sort the packs according to the date of the latest commit.  That
 245  * in turn indicates how young the pack is, and in general we would
 246  * want to depend on younger packs.
 247  */
 248 static unsigned long get_latest_commit_date(struct packed_git *p)
 249 {
 250         unsigned char sha1[20];
 251         struct object *o;
 252         int num = num_packed_objects(p);
 253         int i;
 254         unsigned long latest = 0;
 255
 256         for (i = 0; i < num; i++) {
 257                 if (nth_packed_object_sha1(p, i, sha1))
 258                         die("corrupt pack file %s?", p->pack_name);
 259                 if ((o = parse_object_cheap(sha1)) == NULL)
 260                         die("cannot parse %s", sha1_to_hex(sha1));
 261                 if (o->type == commit_type) {
 262                         struct commit *commit = (struct commit *)o;
 263                         if (latest < commit->date)
 264                                 latest = commit->date;
 265                 }
 266         }
 267         return latest;
 268 }
 269
 270 static int compare_info(const void *a_, const void *b_)
 271 {
 272         struct pack_info * const* a = a_;
 273         struct pack_info * const* b = b_;
 274
 275         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 276                 /* Keep the order in the original */
 277                 return (*a)->old_num - (*b)->old_num;
 278         else if (0 <= (*a)->old_num)
 279                 /* Only A existed in the original so B is obviously newer */
 280                 return -1;
 281         else if (0 <= (*b)->old_num)
 282                 /* The other way around. */
 283                 return 1;
 284
 285         if ((*a)->latest < (*b)->latest)
 286                 return -1;
 287         else if ((*a)->latest == (*b)->latest)
 288                 return 0;
 289         else
 290                 return 1;
 291 }
 292
 293 static void init_pack_info(const char *infofile, int force)
 294 {
 295         struct packed_git *p;
 296         int stale;
 297         int i = 0;
 298         char *dep_temp;
 299
 300         objdir = get_object_directory();
 301         objdirlen = strlen(objdir);
 302
 303         prepare_packed_git();
 304         for (p = packed_git; p; p = p->next) {
 305                 /* we ignore things on alternate path since they are
 306                  * not available to the pullers in general.
 307                  */
 308                 if (strncmp(p->pack_name, objdir, objdirlen) ||
 309                     strncmp(p->pack_name + objdirlen, "/pack/", 6))
 310                         continue;
 311                 i++;
 312         }
 313         num_pack = i;
 314         info = xcalloc(num_pack, sizeof(struct pack_info *));
 315         for (i = 0, p = packed_git; p; p = p->next) {
 316                 if (strncmp(p->pack_name, objdir, objdirlen) ||
 317                     p->pack_name[objdirlen] != '/')
 318                         continue;
 319                 info[i] = xcalloc(1, sizeof(struct pack_info) + num_pack);
 320                 info[i]->p = p;
 321                 info[i]->old_num = -1;
 322                 i++;
 323         }
 324
 325         if (infofile && !force)
 326                 stale = read_pack_info_file(infofile);
 327         else
 328                 stale = 1;
 329
 330         for (i = 0; i < num_pack; i++) {
 331                 if (stale) {
 332                         info[i]->old_num = -1;
 333                         memset(info[i]->dep, 0, num_pack);
 334                         info[i]->nr_heads = 0;
 335                 }
 336                 if (info[i]->old_num < 0)
 337                         info[i]->latest = get_latest_commit_date(info[i]->p);
 338         }
 339
 340         qsort(info, num_pack, sizeof(info[0]), compare_info);
 341         for (i = 0; i < num_pack; i++)
 342                 info[i]->new_num = i;
 343
 344         /* we need to fix up the dependency information
 345          * for the old ones.
 346          */
 347         dep_temp = NULL;
 348         for (i = 0; i < num_pack; i++) {
 349                 int old;
 350
 351                 if (info[i]->old_num < 0)
 352                         continue;
 353                 if (! dep_temp)
 354                         dep_temp = xmalloc(num_pack);
 355                 memset(dep_temp, 0, num_pack);
 356                 for (old = 0; old < num_pack; old++) {
 357                         struct pack_info *base;
 358                         if (!info[i]->dep[old])
 359                                 continue;
 360                         base = find_pack_by_old_num(old);
 361                         if (!base)
 362                                 die("internal error renumbering");
 363                         dep_temp[base->new_num] = 1;
 364                 }
 365                 memcpy(info[i]->dep, dep_temp, num_pack);
 366         }
 367         free(dep_temp);
 368 }
 369
 370 static void write_pack_info_file(FILE *fp)
 371 {
 372         int i, j;
 373         for (i = 0; i < num_pack; i++)
 374                 fprintf(fp, "P %s\n", info[i]->p->pack_name + objdirlen + 6);
 375
 376         for (i = 0; i < num_pack; i++) {
 377                 fprintf(fp, "D %1d", i);
 378                 for (j = 0; j < num_pack; j++) {
 379                         if ((i == j) || !(info[i]->dep[j]))
 380                                 continue;
 381                         fprintf(fp, " %1d", j);
 382                 }
 383                 fputc('\n', fp);
 384         }
 385
 386         for (i = 0; i < num_pack; i++) {
 387                 struct pack_info *this = info[i];
 388                 for (j = 0; j < this->nr_heads; j++) {
 389                         struct object *o = lookup_object(this->head[j]);
 390                         fprintf(fp, "T %1d %s %s\n",
 391                                 i, sha1_to_hex(this->head[j]), o->type);
 392                 }
 393         }
 394
 395 }
 396
 397 #define REFERENCED 01
 398 #define INTERNAL  02
 399 #define EMITTED   04
 400
 401 static void show(struct object *o, int pack_ix)
 402 {
 403         /*
 404          * We are interested in objects that are not referenced,
 405          * and objects that are referenced but not internal.
 406          */
 407         if (o->flags & EMITTED)
 408                 return;
 409
 410         if (!(o->flags & REFERENCED))
 411                 add_head_def(info[pack_ix], o->sha1);
 412         else if ((o->flags & REFERENCED) && !(o->flags & INTERNAL)) {
 413                 int i;
 414
 415                 /* Which pack contains this object?  That is what
 416                  * pack_ix can depend on.  We earlier sorted info
 417                  * array from youngest to oldest, so try newer packs
 418                  * first to favor them here.
 419                  */
 420                 for (i = num_pack - 1; 0 <= i; i--) {
 421                         struct packed_git *p = info[i]->p;
 422                         struct pack_entry ent;
 423                         if (find_pack_entry_one(o->sha1, &ent, p)) {
 424                                 info[pack_ix]->dep[i] = 1;
 425                                 break;
 426                         }
 427                 }
 428         }
 429         o->flags |= EMITTED;
 430 }
 431
 432 static void find_pack_info_one(int pack_ix)
 433 {
 434         unsigned char sha1[20];
 435         struct object *o;
 436         struct object_list *ref;
 437         int i;
 438         struct packed_git *p = info[pack_ix]->p;
 439         int num = num_packed_objects(p);
 440
 441         /* Scan objects, clear flags from all the edge ones and
 442          * internal ones, possibly marked in the previous round.
 443          */
 444         for (i = 0; i < num; i++) {
 445                 if (nth_packed_object_sha1(p, i, sha1))
 446                         die("corrupt pack file %s?", p->pack_name);
 447                 if ((o = lookup_object(sha1)) == NULL)
 448                         die("cannot parse %s", sha1_to_hex(sha1));
 449                 for (ref = o->refs; ref; ref = ref->next)
 450                         ref->item->flags = 0;
 451                 o->flags = 0;
 452         }
 453
 454         /* Mark all the internal ones */
 455         for (i = 0; i < num; i++) {
 456                 if (nth_packed_object_sha1(p, i, sha1))
 457                         die("corrupt pack file %s?", p->pack_name);
 458                 if ((o = lookup_object(sha1)) == NULL)
 459                         die("cannot find %s", sha1_to_hex(sha1));
 460                 for (ref = o->refs; ref; ref = ref->next)
 461                         ref->item->flags |= REFERENCED;
 462                 o->flags |= INTERNAL;
 463         }
 464
 465         for (i = 0; i < num; i++) {
 466                 if (nth_packed_object_sha1(p, i, sha1))
 467                         die("corrupt pack file %s?", p->pack_name);
 468                 if ((o = lookup_object(sha1)) == NULL)
 469                         die("cannot find %s", sha1_to_hex(sha1));
 470
 471                 show(o, pack_ix);
 472                 for (ref = o->refs; ref; ref = ref->next)
 473                         show(ref->item, pack_ix);
 474         }
 475
 476 }
 477
 478 static void find_pack_info(void)
 479 {
 480         int i;
 481         for (i = 0; i < num_pack; i++) {
 482                 /* The packed objects are cast in stone, and a head
 483                  * in a pack will stay as head, so is the set of missing
 484                  * objects.  If the repo has been reorganized and we
 485                  * are missing some packs available back then, we have
 486                  * already discarded the info read from the file, so
 487                  * we will find (old_num < 0) in that case.
 488                  */
 489                 if (0 <= info[i]->old_num)
 490                         continue;
 491                 find_pack_info_one(i);
 492         }
 493 }
 494
 495 static int update_info_packs(int force)
 496 {
 497         char infofile[PATH_MAX];
 498         char name[PATH_MAX];
 499         int namelen;
 500         FILE *fp;
 501
 502         namelen = sprintf(infofile, "%s/info/packs", get_object_directory());
 503         strcpy(name, infofile);
 504         strcpy(name + namelen, "+");
 505
 506         init_pack_info(infofile, force);
 507         find_pack_info();
 508
 509         safe_create_leading_directories(name);
 510         fp = fopen(name, "w");
 511         if (!fp)
 512                 return error("cannot open %s", name);
 513         write_pack_info_file(fp);
 514         fclose(fp);
 515         rename(name, infofile);
 516         return 0;
 517 }
 518
 519 /* rev-cache */
 520 static int record_rev_cache_ref(const char *path, const unsigned char *sha1)
 521 {
 522         struct object *obj = parse_object(sha1);
 523
 524         if (!obj)
 525                 return error("ref %s has bad sha %s", path, sha1_to_hex(sha1));
 526         while (obj && obj->type == tag_type)
 527                 obj = parse_object(((struct tag *)obj)->tagged->sha1);
 528         if (!obj || obj->type != commit_type)
 529                 /* tag pointing at a non-commit */
 530                 return 0;
 531         return record_rev_cache(obj->sha1, NULL);
 532 }
 533
 534 static int update_info_revs(int force)
 535 {
 536         char *path0 = strdup(git_path("info/rev-cache"));
 537         int len = strlen(path0);
 538         char *path1 = xmalloc(len + 2);
 539
 540         strcpy(path1, path0);
 541         strcpy(path1 + len, "+");
 542
 543         /* read existing rev-cache */
 544         if (!force)
 545                 read_rev_cache(path0, NULL, 0);
 546         safe_create_leading_directories(path0);
 547
 548         for_each_ref(record_rev_cache_ref);
 549
 550         /* update the rev-cache database */
 551         write_rev_cache(path1, force ? "/dev/null" : path0);
 552         rename(path1, path0);
 553         free(path1);
 554         free(path0);
 555         return 0;
 556 }
 557
 558 /* public */
 559 int update_server_info(int force)
 560 {
 561         /* We would add more dumb-server support files later,
 562          * including index of available pack files and their
 563          * intended audiences.
 564          */
 565         int errs = 0;
 566
 567         errs = errs | update_info_refs(force);
 568         errs = errs | update_info_packs(force);
 569         errs = errs | update_info_revs(force);
 570
 571         return errs;
 572 }