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 (isspace(*line))
  32                 return NULL;
  33         if (line[len] != '\n')
  34                 return NULL;
  35         line[len] = 0;
  36         return line;
  37 }
  38
  39 static struct ref_list *add_ref(const char *name, const unsigned char *sha1, struct ref_list *list)
  40 {
  41         int len;
  42         struct ref_list **p = &list, *entry;
  43
  44         /* Find the place to insert the ref into.. */
  45         while ((entry = *p) != NULL) {
  46                 int cmp = strcmp(entry->name, name);
  47                 if (cmp > 0)
  48                         break;
  49
  50                 /* Same as existing entry? */
  51                 if (!cmp)
  52                         return list;
  53                 p = &entry->next;
  54         }
  55
  56         /* Allocate it and add it in.. */
  57         len = strlen(name) + 1;
  58         entry = xmalloc(sizeof(struct ref_list) + len);
  59         hashcpy(entry->sha1, sha1);
  60         memcpy(entry->name, name, len);
  61         entry->next = *p;
  62         *p = entry;
  63         return list;
  64 }
  65
  66 static struct ref_list *get_packed_refs(void)
  67 {
  68         static int did_refs = 0;
  69         static struct ref_list *refs = NULL;
  70
  71         if (!did_refs) {
  72                 FILE *f = fopen(git_path("packed-refs"), "r");
  73                 if (f) {
  74                         struct ref_list *list = NULL;
  75                         char refline[PATH_MAX];
  76                         while (fgets(refline, sizeof(refline), f)) {
  77                                 unsigned char sha1[20];
  78                                 const char *name = parse_ref_line(refline, sha1);
  79                                 if (!name)
  80                                         continue;
  81                                 list = add_ref(name, sha1, list);
  82                         }
  83                         fclose(f);
  84                         refs = list;
  85                 }
  86                 did_refs = 1;
  87         }
  88         return refs;
  89 }
  90
  91 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
  92 {
  93         DIR *dir = opendir(git_path("%s", base));
  94
  95         if (dir) {
  96                 struct dirent *de;
  97                 int baselen = strlen(base);
  98                 char *ref = xmalloc(baselen + 257);
  99
 100                 memcpy(ref, base, baselen);
 101                 if (baselen && base[baselen-1] != '/')
 102                         ref[baselen++] = '/';
 103
 104                 while ((de = readdir(dir)) != NULL) {
 105                         unsigned char sha1[20];
 106                         struct stat st;
 107                         int namelen;
 108
 109                         if (de->d_name[0] == '.')
 110                                 continue;
 111                         namelen = strlen(de->d_name);
 112                         if (namelen > 255)
 113                                 continue;
 114                         if (has_extension(de->d_name, ".lock"))
 115                                 continue;
 116                         memcpy(ref + baselen, de->d_name, namelen+1);
 117                         if (stat(git_path("%s", ref), &st) < 0)
 118                                 continue;
 119                         if (S_ISDIR(st.st_mode)) {
 120                                 list = get_ref_dir(ref, list);
 121                                 continue;
 122                         }
 123                         if (read_ref(ref, sha1) < 0) {
 124                                 error("%s points nowhere!", ref);
 125                                 continue;
 126                         }
 127                         list = add_ref(ref, sha1, list);
 128                 }
 129                 free(ref);
 130                 closedir(dir);
 131         }
 132         return list;
 133 }
 134
 135 static struct ref_list *get_loose_refs(void)
 136 {
 137         static int did_refs = 0;
 138         static struct ref_list *refs = NULL;
 139
 140         if (!did_refs) {
 141                 refs = get_ref_dir("refs", NULL);
 142                 did_refs = 1;
 143         }
 144         return refs;
 145 }
 146
 147 /* We allow "recursive" symbolic refs. Only within reason, though */
 148 #define MAXDEPTH 5
 149
 150 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading)
 151 {
 152         int depth = MAXDEPTH, len;
 153         char buffer[256];
 154         static char ref_buffer[256];
 155
 156         for (;;) {
 157                 const char *path = git_path("%s", ref);
 158                 struct stat st;
 159                 char *buf;
 160                 int fd;
 161
 162                 if (--depth < 0)
 163                         return NULL;
 164
 165                 /* Special case: non-existing file.
 166                  * Not having the refs/heads/new-branch is OK
 167                  * if we are writing into it, so is .git/HEAD
 168                  * that points at refs/heads/master still to be
 169                  * born.  It is NOT OK if we are resolving for
 170                  * reading.
 171                  */
 172                 if (lstat(path, &st) < 0) {
 173                         struct ref_list *list = get_packed_refs();
 174                         while (list) {
 175                                 if (!strcmp(ref, list->name)) {
 176                                         hashcpy(sha1, list->sha1);
 177                                         return ref;
 178                                 }
 179                                 list = list->next;
 180                         }
 181                         if (reading || errno != ENOENT)
 182                                 return NULL;
 183                         hashclr(sha1);
 184                         return ref;
 185                 }
 186
 187                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 188                 if (S_ISLNK(st.st_mode)) {
 189                         len = readlink(path, buffer, sizeof(buffer)-1);
 190                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 191                                 buffer[len] = 0;
 192                                 strcpy(ref_buffer, buffer);
 193                                 ref = ref_buffer;
 194                                 continue;
 195                         }
 196                 }
 197
 198                 /*
 199                  * Anything else, just open it and try to use it as
 200                  * a ref
 201                  */
 202                 fd = open(path, O_RDONLY);
 203                 if (fd < 0)
 204                         return NULL;
 205                 len = read(fd, buffer, sizeof(buffer)-1);
 206                 close(fd);
 207
 208                 /*
 209                  * Is it a symbolic ref?
 210                  */
 211                 if (len < 4 || memcmp("ref:", buffer, 4))
 212                         break;
 213                 buf = buffer + 4;
 214                 len -= 4;
 215                 while (len && isspace(*buf))
 216                         buf++, len--;
 217                 while (len && isspace(buf[len-1]))
 218                         len--;
 219                 buf[len] = 0;
 220                 memcpy(ref_buffer, buf, len + 1);
 221                 ref = ref_buffer;
 222         }
 223         if (len < 40 || get_sha1_hex(buffer, sha1))
 224                 return NULL;
 225         return ref;
 226 }
 227
 228 int create_symref(const char *ref_target, const char *refs_heads_master)
 229 {
 230         const char *lockpath;
 231         char ref[1000];
 232         int fd, len, written;
 233         const char *git_HEAD = git_path("%s", ref_target);
 234
 235 #ifndef NO_SYMLINK_HEAD
 236         if (prefer_symlink_refs) {
 237                 unlink(git_HEAD);
 238                 if (!symlink(refs_heads_master, git_HEAD))
 239                         return 0;
 240                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 241         }
 242 #endif
 243
 244         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 245         if (sizeof(ref) <= len) {
 246                 error("refname too long: %s", refs_heads_master);
 247                 return -1;
 248         }
 249         lockpath = mkpath("%s.lock", git_HEAD);
 250         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 251         written = write(fd, ref, len);
 252         close(fd);
 253         if (written != len) {
 254                 unlink(lockpath);
 255                 error("Unable to write to %s", lockpath);
 256                 return -2;
 257         }
 258         if (rename(lockpath, git_HEAD) < 0) {
 259                 unlink(lockpath);
 260                 error("Unable to create %s", git_HEAD);
 261                 return -3;
 262         }
 263         if (adjust_shared_perm(git_HEAD)) {
 264                 unlink(lockpath);
 265                 error("Unable to fix permissions on %s", lockpath);
 266                 return -4;
 267         }
 268         return 0;
 269 }
 270
 271 int read_ref(const char *ref, unsigned char *sha1)
 272 {
 273         if (resolve_ref(ref, sha1, 1))
 274                 return 0;
 275         return -1;
 276 }
 277
 278 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 279 {
 280         int retval;
 281         struct ref_list *packed = get_packed_refs();
 282         struct ref_list *loose = get_loose_refs();
 283
 284         while (packed && loose) {
 285                 struct ref_list *entry;
 286                 int cmp = strcmp(packed->name, loose->name);
 287                 if (!cmp) {
 288                         packed = packed->next;
 289                         continue;
 290                 }
 291                 if (cmp > 0) {
 292                         entry = loose;
 293                         loose = loose->next;
 294                 } else {
 295                         entry = packed;
 296                         packed = packed->next;
 297                 }
 298                 if (strncmp(base, entry->name, trim))
 299                         continue;
 300                 if (is_null_sha1(entry->sha1))
 301                         continue;
 302                 if (!has_sha1_file(entry->sha1)) {
 303                         error("%s does not point to a valid object!", entry->name);
 304                         continue;
 305                 }
 306                 retval = fn(entry->name + trim, entry->sha1);
 307                 if (retval)
 308                         return retval;
 309         }
 310
 311         packed = packed ? packed : loose;
 312         while (packed) {
 313                 if (!strncmp(base, packed->name, trim)) {
 314                         retval = fn(packed->name + trim, packed->sha1);
 315                         if (retval)
 316                                 return retval;
 317                 }
 318                 packed = packed->next;
 319         }
 320         return 0;
 321 }
 322
 323 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 324 {
 325         unsigned char sha1[20];
 326         if (!read_ref("HEAD", sha1))
 327                 return fn("HEAD", sha1);
 328         return 0;
 329 }
 330
 331 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 332 {
 333         return do_for_each_ref("refs/", fn, 0);
 334 }
 335
 336 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 337 {
 338         return do_for_each_ref("refs/tags/", fn, 10);
 339 }
 340
 341 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 342 {
 343         return do_for_each_ref("refs/heads/", fn, 11);
 344 }
 345
 346 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 347 {
 348         return do_for_each_ref("refs/remotes/", fn, 13);
 349 }
 350
 351 int get_ref_sha1(const char *ref, unsigned char *sha1)
 352 {
 353         if (check_ref_format(ref))
 354                 return -1;
 355         return read_ref(mkpath("refs/%s", ref), sha1);
 356 }
 357
 358 /*
 359  * Make sure "ref" is something reasonable to have under ".git/refs/";
 360  * We do not like it if:
 361  *
 362  * - any path component of it begins with ".", or
 363  * - it has double dots "..", or
 364  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 365  * - it ends with a "/".
 366  */
 367
 368 static inline int bad_ref_char(int ch)
 369 {
 370         return (((unsigned) ch) <= ' ' ||
 371                 ch == '~' || ch == '^' || ch == ':' ||
 372                 /* 2.13 Pattern Matching Notation */
 373                 ch == '?' || ch == '*' || ch == '[');
 374 }
 375
 376 int check_ref_format(const char *ref)
 377 {
 378         int ch, level;
 379         const char *cp = ref;
 380
 381         level = 0;
 382         while (1) {
 383                 while ((ch = *cp++) == '/')
 384                         ; /* tolerate duplicated slashes */
 385                 if (!ch)
 386                         return -1; /* should not end with slashes */
 387
 388                 /* we are at the beginning of the path component */
 389                 if (ch == '.' || bad_ref_char(ch))
 390                         return -1;
 391
 392                 /* scan the rest of the path component */
 393                 while ((ch = *cp++) != 0) {
 394                         if (bad_ref_char(ch))
 395                                 return -1;
 396                         if (ch == '/')
 397                                 break;
 398                         if (ch == '.' && *cp == '.')
 399                                 return -1;
 400                 }
 401                 level++;
 402                 if (!ch) {
 403                         if (level < 2)
 404                                 return -1; /* at least of form "heads/blah" */
 405                         return 0;
 406                 }
 407         }
 408 }
 409
 410 static struct ref_lock *verify_lock(struct ref_lock *lock,
 411         const unsigned char *old_sha1, int mustexist)
 412 {
 413         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist)) {
 414                 error("Can't verify ref %s", lock->ref_name);
 415                 unlock_ref(lock);
 416                 return NULL;
 417         }
 418         if (hashcmp(lock->old_sha1, old_sha1)) {
 419                 error("Ref %s is at %s but expected %s", lock->ref_name,
 420                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 421                 unlock_ref(lock);
 422                 return NULL;
 423         }
 424         return lock;
 425 }
 426
 427 static struct ref_lock *lock_ref_sha1_basic(const char *ref,
 428         int plen,
 429         const unsigned char *old_sha1, int mustexist)
 430 {
 431         char *ref_file;
 432         const char *orig_ref = ref;
 433         struct ref_lock *lock;
 434         struct stat st;
 435
 436         lock = xcalloc(1, sizeof(struct ref_lock));
 437         lock->lock_fd = -1;
 438
 439         ref = resolve_ref(ref, lock->old_sha1, mustexist);
 440         if (!ref) {
 441                 int last_errno = errno;
 442                 error("unable to resolve reference %s: %s",
 443                         orig_ref, strerror(errno));
 444                 unlock_ref(lock);
 445                 errno = last_errno;
 446                 return NULL;
 447         }
 448         lock->lk = xcalloc(1, sizeof(struct lock_file));
 449
 450         lock->ref_name = xstrdup(ref);
 451         lock->log_file = xstrdup(git_path("logs/%s", ref));
 452         ref_file = git_path(ref);
 453         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 454
 455         if (safe_create_leading_directories(ref_file))
 456                 die("unable to create directory for %s", ref_file);
 457         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 458
 459         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 460 }
 461
 462 struct ref_lock *lock_ref_sha1(const char *ref,
 463         const unsigned char *old_sha1, int mustexist)
 464 {
 465         if (check_ref_format(ref))
 466                 return NULL;
 467         return lock_ref_sha1_basic(mkpath("refs/%s", ref),
 468                 5 + strlen(ref), old_sha1, mustexist);
 469 }
 470
 471 struct ref_lock *lock_any_ref_for_update(const char *ref,
 472         const unsigned char *old_sha1, int mustexist)
 473 {
 474         return lock_ref_sha1_basic(ref, strlen(ref), old_sha1, mustexist);
 475 }
 476
 477 void unlock_ref(struct ref_lock *lock)
 478 {
 479         if (lock->lock_fd >= 0) {
 480                 close(lock->lock_fd);
 481                 /* Do not free lock->lk -- atexit() still looks at them */
 482                 if (lock->lk)
 483                         rollback_lock_file(lock->lk);
 484         }
 485         free(lock->ref_name);
 486         free(lock->log_file);
 487         free(lock);
 488 }
 489
 490 static int log_ref_write(struct ref_lock *lock,
 491         const unsigned char *sha1, const char *msg)
 492 {
 493         int logfd, written, oflags = O_APPEND | O_WRONLY;
 494         unsigned maxlen, len;
 495         char *logrec;
 496         const char *committer;
 497
 498         if (log_all_ref_updates) {
 499                 if (safe_create_leading_directories(lock->log_file) < 0)
 500                         return error("unable to create directory for %s",
 501                                 lock->log_file);
 502                 oflags |= O_CREAT;
 503         }
 504
 505         logfd = open(lock->log_file, oflags, 0666);
 506         if (logfd < 0) {
 507                 if (!log_all_ref_updates && errno == ENOENT)
 508                         return 0;
 509                 return error("Unable to append to %s: %s",
 510                         lock->log_file, strerror(errno));
 511         }
 512
 513         committer = git_committer_info(1);
 514         if (msg) {
 515                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 516                 logrec = xmalloc(maxlen);
 517                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 518                         sha1_to_hex(lock->old_sha1),
 519                         sha1_to_hex(sha1),
 520                         committer,
 521                         msg);
 522         }
 523         else {
 524                 maxlen = strlen(committer) + 2*40 + 4;
 525                 logrec = xmalloc(maxlen);
 526                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 527                         sha1_to_hex(lock->old_sha1),
 528                         sha1_to_hex(sha1),
 529                         committer);
 530         }
 531         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 532         free(logrec);
 533         close(logfd);
 534         if (written != len)
 535                 return error("Unable to append to %s", lock->log_file);
 536         return 0;
 537 }
 538
 539 int write_ref_sha1(struct ref_lock *lock,
 540         const unsigned char *sha1, const char *logmsg)
 541 {
 542         static char term = '\n';
 543
 544         if (!lock)
 545                 return -1;
 546         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 547                 unlock_ref(lock);
 548                 return 0;
 549         }
 550         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 551             write(lock->lock_fd, &term, 1) != 1
 552                 || close(lock->lock_fd) < 0) {
 553                 error("Couldn't write %s", lock->lk->filename);
 554                 unlock_ref(lock);
 555                 return -1;
 556         }
 557         if (log_ref_write(lock, sha1, logmsg) < 0) {
 558                 unlock_ref(lock);
 559                 return -1;
 560         }
 561         if (commit_lock_file(lock->lk)) {
 562                 error("Couldn't set %s", lock->ref_name);
 563                 unlock_ref(lock);
 564                 return -1;
 565         }
 566         lock->lock_fd = -1;
 567         unlock_ref(lock);
 568         return 0;
 569 }
 570
 571 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 572 {
 573         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 574         char *tz_c;
 575         int logfd, tz;
 576         struct stat st;
 577         unsigned long date;
 578         unsigned char logged_sha1[20];
 579
 580         logfile = git_path("logs/%s", ref);
 581         logfd = open(logfile, O_RDONLY, 0);
 582         if (logfd < 0)
 583                 die("Unable to read log %s: %s", logfile, strerror(errno));
 584         fstat(logfd, &st);
 585         if (!st.st_size)
 586                 die("Log %s is empty.", logfile);
 587         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 588         close(logfd);
 589
 590         lastrec = NULL;
 591         rec = logend = logdata + st.st_size;
 592         while (logdata < rec) {
 593                 if (logdata < rec && *(rec-1) == '\n')
 594                         rec--;
 595                 lastgt = NULL;
 596                 while (logdata < rec && *(rec-1) != '\n') {
 597                         rec--;
 598                         if (*rec == '>')
 599                                 lastgt = rec;
 600                 }
 601                 if (!lastgt)
 602                         die("Log %s is corrupt.", logfile);
 603                 date = strtoul(lastgt + 1, &tz_c, 10);
 604                 if (date <= at_time) {
 605                         if (lastrec) {
 606                                 if (get_sha1_hex(lastrec, logged_sha1))
 607                                         die("Log %s is corrupt.", logfile);
 608                                 if (get_sha1_hex(rec + 41, 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 has gap after %s.\n",
 614                                                 logfile, show_rfc2822_date(date, tz));
 615                                 }
 616                         }
 617                         else if (date == at_time) {
 618                                 if (get_sha1_hex(rec + 41, sha1))
 619                                         die("Log %s is corrupt.", logfile);
 620                         }
 621                         else {
 622                                 if (get_sha1_hex(rec + 41, logged_sha1))
 623                                         die("Log %s is corrupt.", logfile);
 624                                 if (hashcmp(logged_sha1, sha1)) {
 625                                         tz = strtoul(tz_c, NULL, 10);
 626                                         fprintf(stderr,
 627                                                 "warning: Log %s unexpectedly ended on %s.\n",
 628                                                 logfile, show_rfc2822_date(date, tz));
 629                                 }
 630                         }
 631                         munmap((void*)logdata, st.st_size);
 632                         return 0;
 633                 }
 634                 lastrec = rec;
 635         }
 636
 637         rec = logdata;
 638         while (rec < logend && *rec != '>' && *rec != '\n')
 639                 rec++;
 640         if (rec == logend || *rec == '\n')
 641                 die("Log %s is corrupt.", logfile);
 642         date = strtoul(rec + 1, &tz_c, 10);
 643         tz = strtoul(tz_c, NULL, 10);
 644         if (get_sha1_hex(logdata, sha1))
 645                 die("Log %s is corrupt.", logfile);
 646         munmap((void*)logdata, st.st_size);
 647         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 648                 logfile, show_rfc2822_date(date, tz));
 649         return 0;
 650 }