refs.c

   1 #include "refs.h"
   2 #include "cache.h"
   3
   4 #include <errno.h>
   5
   6 struct ref_list {
   7         struct ref_list *next;
   8         unsigned char sha1[20];
   9         char name[FLEX_ARRAY];
  10 };
  11
  12 static const char *parse_ref_line(char *line, unsigned char *sha1)
  13 {
  14         /*
  15          * 42: the answer to everything.
  16          *
  17          * In this case, it happens to be the answer to
  18          *  40 (length of sha1 hex representation)
  19          *  +1 (space in between hex and name)
  20          *  +1 (newline at the end of the line)
  21          */
  22         int len = strlen(line) - 42;
  23
  24         if (len <= 0)
  25                 return NULL;
  26         if (get_sha1_hex(line, sha1) < 0)
  27                 return NULL;
  28         if (!isspace(line[40]))
  29                 return NULL;
  30         line += 41;
  31         if (line[len] != '\n')
  32                 return NULL;
  33         line[len] = 0;
  34         return line;
  35 }
  36
  37 static struct ref_list *add_ref(const char *name, const unsigned char *sha1, struct ref_list *list)
  38 {
  39         int len;
  40         struct ref_list **p = &list, *entry;
  41
  42         /* Find the place to insert the ref into.. */
  43         while ((entry = *p) != NULL) {
  44                 int cmp = strcmp(entry->name, name);
  45                 if (cmp > 0)
  46                         break;
  47
  48                 /* Same as existing entry? */
  49                 if (!cmp)
  50                         return list;
  51                 p = &entry->next;
  52         }
  53
  54         /* Allocate it and add it in.. */
  55         len = strlen(name) + 1;
  56         entry = xmalloc(sizeof(struct ref_list) + len);
  57         hashcpy(entry->sha1, sha1);
  58         memcpy(entry->name, name, len);
  59         entry->next = *p;
  60         *p = entry;
  61         return list;
  62 }
  63
  64 static struct ref_list *get_packed_refs(void)
  65 {
  66         static int did_refs = 0;
  67         static struct ref_list *refs = NULL;
  68
  69         if (!did_refs) {
  70                 FILE *f = fopen(git_path("packed-refs"), "r");
  71                 if (f) {
  72                         struct ref_list *list = NULL;
  73                         char refline[PATH_MAX];
  74                         while (fgets(refline, sizeof(refline), f)) {
  75                                 unsigned char sha1[20];
  76                                 const char *name = parse_ref_line(refline, sha1);
  77                                 if (!name)
  78                                         continue;
  79                                 list = add_ref(name, sha1, list);
  80                         }
  81                         fclose(f);
  82                         refs = list;
  83                 }
  84                 did_refs = 1;
  85         }
  86         return refs;
  87 }
  88
  89 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
  90 {
  91         DIR *dir = opendir(git_path("%s", base));
  92
  93         if (dir) {
  94                 struct dirent *de;
  95                 int baselen = strlen(base);
  96                 char *path = xmalloc(baselen + 257);
  97
  98                 memcpy(path, base, baselen);
  99                 if (baselen && base[baselen-1] != '/')
 100                         path[baselen++] = '/';
 101
 102                 while ((de = readdir(dir)) != NULL) {
 103                         unsigned char sha1[20];
 104                         struct stat st;
 105                         int namelen;
 106
 107                         if (de->d_name[0] == '.')
 108                                 continue;
 109                         namelen = strlen(de->d_name);
 110                         if (namelen > 255)
 111                                 continue;
 112                         if (has_extension(de->d_name, ".lock"))
 113                                 continue;
 114                         memcpy(path + baselen, de->d_name, namelen+1);
 115                         if (stat(git_path("%s", path), &st) < 0)
 116                                 continue;
 117                         if (S_ISDIR(st.st_mode)) {
 118                                 list = get_ref_dir(path, list);
 119                                 continue;
 120                         }
 121                         if (read_ref(git_path("%s", path), sha1) < 0) {
 122                                 error("%s points nowhere!", path);
 123                                 continue;
 124                         }
 125                         list = add_ref(path, sha1, list);
 126                 }
 127                 free(path);
 128                 closedir(dir);
 129         }
 130         return list;
 131 }
 132
 133 static struct ref_list *get_loose_refs(void)
 134 {
 135         static int did_refs = 0;
 136         static struct ref_list *refs = NULL;
 137
 138         if (!did_refs) {
 139                 refs = get_ref_dir("refs", NULL);
 140                 did_refs = 1;
 141         }
 142         return refs;
 143 }
 144
 145 /* We allow "recursive" symbolic refs. Only within reason, though */
 146 #define MAXDEPTH 5
 147
 148 const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
 149 {
 150         int depth = MAXDEPTH, len;
 151         char buffer[256];
 152
 153         for (;;) {
 154                 struct stat st;
 155                 char *buf;
 156                 int fd;
 157
 158                 if (--depth < 0)
 159                         return NULL;
 160
 161                 /* Special case: non-existing file.
 162                  * Not having the refs/heads/new-branch is OK
 163                  * if we are writing into it, so is .git/HEAD
 164                  * that points at refs/heads/master still to be
 165                  * born.  It is NOT OK if we are resolving for
 166                  * reading.
 167                  */
 168                 if (lstat(path, &st) < 0) {
 169                         if (reading || errno != ENOENT)
 170                                 return NULL;
 171                         hashclr(sha1);
 172                         return path;
 173                 }
 174
 175                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 176                 if (S_ISLNK(st.st_mode)) {
 177                         len = readlink(path, buffer, sizeof(buffer)-1);
 178                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 179                                 path = git_path("%.*s", len, buffer);
 180                                 continue;
 181                         }
 182                 }
 183
 184                 /*
 185                  * Anything else, just open it and try to use it as
 186                  * a ref
 187                  */
 188                 fd = open(path, O_RDONLY);
 189                 if (fd < 0)
 190                         return NULL;
 191                 len = read(fd, buffer, sizeof(buffer)-1);
 192                 close(fd);
 193
 194                 /*
 195                  * Is it a symbolic ref?
 196                  */
 197                 if (len < 4 || memcmp("ref:", buffer, 4))
 198                         break;
 199                 buf = buffer + 4;
 200                 len -= 4;
 201                 while (len && isspace(*buf))
 202                         buf++, len--;
 203                 while (len && isspace(buf[len-1]))
 204                         buf[--len] = 0;
 205                 path = git_path("%.*s", len, buf);
 206         }
 207         if (len < 40 || get_sha1_hex(buffer, sha1))
 208                 return NULL;
 209         return path;
 210 }
 211
 212 int create_symref(const char *git_HEAD, const char *refs_heads_master)
 213 {
 214         const char *lockpath;
 215         char ref[1000];
 216         int fd, len, written;
 217
 218 #ifndef NO_SYMLINK_HEAD
 219         if (prefer_symlink_refs) {
 220                 unlink(git_HEAD);
 221                 if (!symlink(refs_heads_master, git_HEAD))
 222                         return 0;
 223                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 224         }
 225 #endif
 226
 227         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 228         if (sizeof(ref) <= len) {
 229                 error("refname too long: %s", refs_heads_master);
 230                 return -1;
 231         }
 232         lockpath = mkpath("%s.lock", git_HEAD);
 233         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 234         written = write(fd, ref, len);
 235         close(fd);
 236         if (written != len) {
 237                 unlink(lockpath);
 238                 error("Unable to write to %s", lockpath);
 239                 return -2;
 240         }
 241         if (rename(lockpath, git_HEAD) < 0) {
 242                 unlink(lockpath);
 243                 error("Unable to create %s", git_HEAD);
 244                 return -3;
 245         }
 246         if (adjust_shared_perm(git_HEAD)) {
 247                 unlink(lockpath);
 248                 error("Unable to fix permissions on %s", lockpath);
 249                 return -4;
 250         }
 251         return 0;
 252 }
 253
 254 int read_ref(const char *filename, unsigned char *sha1)
 255 {
 256         if (resolve_ref(filename, sha1, 1))
 257                 return 0;
 258         return -1;
 259 }
 260
 261 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 262 {
 263         int retval;
 264         struct ref_list *packed = get_packed_refs();
 265         struct ref_list *loose = get_loose_refs();
 266
 267         while (packed && loose) {
 268                 struct ref_list *entry;
 269                 int cmp = strcmp(packed->name, loose->name);
 270                 if (!cmp) {
 271                         packed = packed->next;
 272                         continue;
 273                 }
 274                 if (cmp > 0) {
 275                         entry = loose;
 276                         loose = loose->next;
 277                 } else {
 278                         entry = packed;
 279                         packed = packed->next;
 280                 }
 281                 if (strncmp(base, entry->name, trim))
 282                         continue;
 283                 retval = fn(entry->name + trim, entry->sha1);
 284                 if (retval)
 285                         return retval;
 286         }
 287
 288         packed = packed ? packed : loose;
 289         while (packed) {
 290                 if (!strncmp(base, packed->name, trim)) {
 291                         retval = fn(packed->name + trim, packed->sha1);
 292                         if (retval)
 293                                 return retval;
 294                 }
 295                 packed = packed->next;
 296         }
 297         return 0;
 298 }
 299
 300 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 301 {
 302         unsigned char sha1[20];
 303         if (!read_ref(git_path("HEAD"), sha1))
 304                 return fn("HEAD", sha1);
 305         return 0;
 306 }
 307
 308 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 309 {
 310         return do_for_each_ref("refs/", fn, 0);
 311 }
 312
 313 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 314 {
 315         return do_for_each_ref("refs/tags/", fn, 10);
 316 }
 317
 318 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 319 {
 320         return do_for_each_ref("refs/heads/", fn, 11);
 321 }
 322
 323 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 324 {
 325         return do_for_each_ref("refs/remotes/", fn, 13);
 326 }
 327
 328 int get_ref_sha1(const char *ref, unsigned char *sha1)
 329 {
 330         if (check_ref_format(ref))
 331                 return -1;
 332         return read_ref(git_path("refs/%s", ref), sha1);
 333 }
 334
 335 /*
 336  * Make sure "ref" is something reasonable to have under ".git/refs/";
 337  * We do not like it if:
 338  *
 339  * - any path component of it begins with ".", or
 340  * - it has double dots "..", or
 341  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 342  * - it ends with a "/".
 343  */
 344
 345 static inline int bad_ref_char(int ch)
 346 {
 347         return (((unsigned) ch) <= ' ' ||
 348                 ch == '~' || ch == '^' || ch == ':' ||
 349                 /* 2.13 Pattern Matching Notation */
 350                 ch == '?' || ch == '*' || ch == '[');
 351 }
 352
 353 int check_ref_format(const char *ref)
 354 {
 355         int ch, level;
 356         const char *cp = ref;
 357
 358         level = 0;
 359         while (1) {
 360                 while ((ch = *cp++) == '/')
 361                         ; /* tolerate duplicated slashes */
 362                 if (!ch)
 363                         return -1; /* should not end with slashes */
 364
 365                 /* we are at the beginning of the path component */
 366                 if (ch == '.' || bad_ref_char(ch))
 367                         return -1;
 368
 369                 /* scan the rest of the path component */
 370                 while ((ch = *cp++) != 0) {
 371                         if (bad_ref_char(ch))
 372                                 return -1;
 373                         if (ch == '/')
 374                                 break;
 375                         if (ch == '.' && *cp == '.')
 376                                 return -1;
 377                 }
 378                 level++;
 379                 if (!ch) {
 380                         if (level < 2)
 381                                 return -1; /* at least of form "heads/blah" */
 382                         return 0;
 383                 }
 384         }
 385 }
 386
 387 static struct ref_lock *verify_lock(struct ref_lock *lock,
 388         const unsigned char *old_sha1, int mustexist)
 389 {
 390         char buf[40];
 391         int nr, fd = open(lock->ref_file, O_RDONLY);
 392         if (fd < 0 && (mustexist || errno != ENOENT)) {
 393                 error("Can't verify ref %s", lock->ref_file);
 394                 unlock_ref(lock);
 395                 return NULL;
 396         }
 397         nr = read(fd, buf, 40);
 398         close(fd);
 399         if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 400                 error("Can't verify ref %s", lock->ref_file);
 401                 unlock_ref(lock);
 402                 return NULL;
 403         }
 404         if (hashcmp(lock->old_sha1, old_sha1)) {
 405                 error("Ref %s is at %s but expected %s", lock->ref_file,
 406                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 407                 unlock_ref(lock);
 408                 return NULL;
 409         }
 410         return lock;
 411 }
 412
 413 static struct ref_lock *lock_ref_sha1_basic(const char *path,
 414         int plen,
 415         const unsigned char *old_sha1, int mustexist)
 416 {
 417         const char *orig_path = path;
 418         struct ref_lock *lock;
 419         struct stat st;
 420
 421         lock = xcalloc(1, sizeof(struct ref_lock));
 422         lock->lock_fd = -1;
 423
 424         plen = strlen(path) - plen;
 425         path = resolve_ref(path, lock->old_sha1, mustexist);
 426         if (!path) {
 427                 int last_errno = errno;
 428                 error("unable to resolve reference %s: %s",
 429                         orig_path, strerror(errno));
 430                 unlock_ref(lock);
 431                 errno = last_errno;
 432                 return NULL;
 433         }
 434         lock->lk = xcalloc(1, sizeof(struct lock_file));
 435
 436         lock->ref_file = xstrdup(path);
 437         lock->log_file = xstrdup(git_path("logs/%s", lock->ref_file + plen));
 438         lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 439
 440         if (safe_create_leading_directories(lock->ref_file))
 441                 die("unable to create directory for %s", lock->ref_file);
 442         lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 443
 444         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 445 }
 446
 447 struct ref_lock *lock_ref_sha1(const char *ref,
 448         const unsigned char *old_sha1, int mustexist)
 449 {
 450         if (check_ref_format(ref))
 451                 return NULL;
 452         return lock_ref_sha1_basic(git_path("refs/%s", ref),
 453                 5 + strlen(ref), old_sha1, mustexist);
 454 }
 455
 456 struct ref_lock *lock_any_ref_for_update(const char *ref,
 457         const unsigned char *old_sha1, int mustexist)
 458 {
 459         return lock_ref_sha1_basic(git_path("%s", ref),
 460                 strlen(ref), old_sha1, mustexist);
 461 }
 462
 463 void unlock_ref(struct ref_lock *lock)
 464 {
 465         if (lock->lock_fd >= 0) {
 466                 close(lock->lock_fd);
 467                 /* Do not free lock->lk -- atexit() still looks at them */
 468                 if (lock->lk)
 469                         rollback_lock_file(lock->lk);
 470         }
 471         free(lock->ref_file);
 472         free(lock->log_file);
 473         free(lock);
 474 }
 475
 476 static int log_ref_write(struct ref_lock *lock,
 477         const unsigned char *sha1, const char *msg)
 478 {
 479         int logfd, written, oflags = O_APPEND | O_WRONLY;
 480         unsigned maxlen, len;
 481         char *logrec;
 482         const char *committer;
 483
 484         if (log_all_ref_updates) {
 485                 if (safe_create_leading_directories(lock->log_file) < 0)
 486                         return error("unable to create directory for %s",
 487                                 lock->log_file);
 488                 oflags |= O_CREAT;
 489         }
 490
 491         logfd = open(lock->log_file, oflags, 0666);
 492         if (logfd < 0) {
 493                 if (!log_all_ref_updates && errno == ENOENT)
 494                         return 0;
 495                 return error("Unable to append to %s: %s",
 496                         lock->log_file, strerror(errno));
 497         }
 498
 499         committer = git_committer_info(1);
 500         if (msg) {
 501                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 502                 logrec = xmalloc(maxlen);
 503                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 504                         sha1_to_hex(lock->old_sha1),
 505                         sha1_to_hex(sha1),
 506                         committer,
 507                         msg);
 508         }
 509         else {
 510                 maxlen = strlen(committer) + 2*40 + 4;
 511                 logrec = xmalloc(maxlen);
 512                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 513                         sha1_to_hex(lock->old_sha1),
 514                         sha1_to_hex(sha1),
 515                         committer);
 516         }
 517         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 518         free(logrec);
 519         close(logfd);
 520         if (written != len)
 521                 return error("Unable to append to %s", lock->log_file);
 522         return 0;
 523 }
 524
 525 int write_ref_sha1(struct ref_lock *lock,
 526         const unsigned char *sha1, const char *logmsg)
 527 {
 528         static char term = '\n';
 529
 530         if (!lock)
 531                 return -1;
 532         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 533                 unlock_ref(lock);
 534                 return 0;
 535         }
 536         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 537             write(lock->lock_fd, &term, 1) != 1
 538                 || close(lock->lock_fd) < 0) {
 539                 error("Couldn't write %s", lock->lk->filename);
 540                 unlock_ref(lock);
 541                 return -1;
 542         }
 543         if (log_ref_write(lock, sha1, logmsg) < 0) {
 544                 unlock_ref(lock);
 545                 return -1;
 546         }
 547         if (commit_lock_file(lock->lk)) {
 548                 error("Couldn't set %s", lock->ref_file);
 549                 unlock_ref(lock);
 550                 return -1;
 551         }
 552         lock->lock_fd = -1;
 553         unlock_ref(lock);
 554         return 0;
 555 }
 556
 557 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 558 {
 559         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 560         char *tz_c;
 561         int logfd, tz;
 562         struct stat st;
 563         unsigned long date;
 564         unsigned char logged_sha1[20];
 565
 566         logfile = git_path("logs/%s", ref);
 567         logfd = open(logfile, O_RDONLY, 0);
 568         if (logfd < 0)
 569                 die("Unable to read log %s: %s", logfile, strerror(errno));
 570         fstat(logfd, &st);
 571         if (!st.st_size)
 572                 die("Log %s is empty.", logfile);
 573         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 574         close(logfd);
 575
 576         lastrec = NULL;
 577         rec = logend = logdata + st.st_size;
 578         while (logdata < rec) {
 579                 if (logdata < rec && *(rec-1) == '\n')
 580                         rec--;
 581                 lastgt = NULL;
 582                 while (logdata < rec && *(rec-1) != '\n') {
 583                         rec--;
 584                         if (*rec == '>')
 585                                 lastgt = rec;
 586                 }
 587                 if (!lastgt)
 588                         die("Log %s is corrupt.", logfile);
 589                 date = strtoul(lastgt + 1, &tz_c, 10);
 590                 if (date <= at_time) {
 591                         if (lastrec) {
 592                                 if (get_sha1_hex(lastrec, logged_sha1))
 593                                         die("Log %s is corrupt.", logfile);
 594                                 if (get_sha1_hex(rec + 41, sha1))
 595                                         die("Log %s is corrupt.", logfile);
 596                                 if (hashcmp(logged_sha1, sha1)) {
 597                                         tz = strtoul(tz_c, NULL, 10);
 598                                         fprintf(stderr,
 599                                                 "warning: Log %s has gap after %s.\n",
 600                                                 logfile, show_rfc2822_date(date, tz));
 601                                 }
 602                         }
 603                         else if (date == at_time) {
 604                                 if (get_sha1_hex(rec + 41, sha1))
 605                                         die("Log %s is corrupt.", logfile);
 606                         }
 607                         else {
 608                                 if (get_sha1_hex(rec + 41, logged_sha1))
 609                                         die("Log %s is corrupt.", logfile);
 610                                 if (hashcmp(logged_sha1, sha1)) {
 611                                         tz = strtoul(tz_c, NULL, 10);
 612                                         fprintf(stderr,
 613                                                 "warning: Log %s unexpectedly ended on %s.\n",
 614                                                 logfile, show_rfc2822_date(date, tz));
 615                                 }
 616                         }
 617                         munmap((void*)logdata, st.st_size);
 618                         return 0;
 619                 }
 620                 lastrec = rec;
 621         }
 622
 623         rec = logdata;
 624         while (rec < logend && *rec != '>' && *rec != '\n')
 625                 rec++;
 626         if (rec == logend || *rec == '\n')
 627                 die("Log %s is corrupt.", logfile);
 628         date = strtoul(rec + 1, &tz_c, 10);
 629         tz = strtoul(tz_c, NULL, 10);
 630         if (get_sha1_hex(logdata, sha1))
 631                 die("Log %s is corrupt.", logfile);
 632         munmap((void*)logdata, st.st_size);
 633         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 634                 logfile, show_rfc2822_date(date, tz));
 635         return 0;
 636 }