git.oblomov.eu Git - git/blob - 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, each_ref_fn fn, int trim, void *cb_data)
 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, cb_data);
 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, cb_data);
 315                         if (retval)
 316                                 return retval;
 317                 }
 318                 packed = packed->next;
 319         }
 320         return 0;
 321 }
 322
 323 int head_ref(each_ref_fn fn, void *cb_data)
 324 {
 325         unsigned char sha1[20];
 326         if (!read_ref("HEAD", sha1))
 327                 return fn("HEAD", sha1, cb_data);
 328         return 0;
 329 }
 330
 331 int for_each_ref(each_ref_fn fn, void *cb_data)
 332 {
 333         return do_for_each_ref("refs/", fn, 0, cb_data);
 334 }
 335
 336 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 337 {
 338         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 339 }
 340
 341 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 342 {
 343         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 344 }
 345
 346 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 347 {
 348         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 349 }
 350
 351 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 352  * caller should do resolve_ref or read_ref like everybody else.  Or
 353  * maybe everybody else should use get_ref_sha1() instead of doing
 354  * read_ref().
 355  */
 356 int get_ref_sha1(const char *ref, unsigned char *sha1)
 357 {
 358         if (check_ref_format(ref))
 359                 return -1;
 360         return read_ref(mkpath("refs/%s", ref), sha1);
 361 }
 362
 363 /*
 364  * Make sure "ref" is something reasonable to have under ".git/refs/";
 365  * We do not like it if:
 366  *
 367  * - any path component of it begins with ".", or
 368  * - it has double dots "..", or
 369  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 370  * - it ends with a "/".
 371  */
 372
 373 static inline int bad_ref_char(int ch)
 374 {
 375         return (((unsigned) ch) <= ' ' ||
 376                 ch == '~' || ch == '^' || ch == ':' ||
 377                 /* 2.13 Pattern Matching Notation */
 378                 ch == '?' || ch == '*' || ch == '[');
 379 }
 380
 381 int check_ref_format(const char *ref)
 382 {
 383         int ch, level;
 384         const char *cp = ref;
 385
 386         level = 0;
 387         while (1) {
 388                 while ((ch = *cp++) == '/')
 389                         ; /* tolerate duplicated slashes */
 390                 if (!ch)
 391                         return -1; /* should not end with slashes */
 392
 393                 /* we are at the beginning of the path component */
 394                 if (ch == '.' || bad_ref_char(ch))
 395                         return -1;
 396
 397                 /* scan the rest of the path component */
 398                 while ((ch = *cp++) != 0) {
 399                         if (bad_ref_char(ch))
 400                                 return -1;
 401                         if (ch == '/')
 402                                 break;
 403                         if (ch == '.' && *cp == '.')
 404                                 return -1;
 405                 }
 406                 level++;
 407                 if (!ch) {
 408                         if (level < 2)
 409                                 return -1; /* at least of form "heads/blah" */
 410                         return 0;
 411                 }
 412         }
 413 }
 414
 415 static struct ref_lock *verify_lock(struct ref_lock *lock,
 416         const unsigned char *old_sha1, int mustexist)
 417 {
 418         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist)) {
 419                 error("Can't verify ref %s", lock->ref_name);
 420                 unlock_ref(lock);
 421                 return NULL;
 422         }
 423         if (hashcmp(lock->old_sha1, old_sha1)) {
 424                 error("Ref %s is at %s but expected %s", lock->ref_name,
 425                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 426                 unlock_ref(lock);
 427                 return NULL;
 428         }
 429         return lock;
 430 }
 431
 432 static struct ref_lock *lock_ref_sha1_basic(const char *ref,
 433         int plen,
 434         const unsigned char *old_sha1, int mustexist)
 435 {
 436         char *ref_file;
 437         const char *orig_ref = ref;
 438         struct ref_lock *lock;
 439         struct stat st;
 440
 441         lock = xcalloc(1, sizeof(struct ref_lock));
 442         lock->lock_fd = -1;
 443
 444         ref = resolve_ref(ref, lock->old_sha1, mustexist);
 445         if (!ref) {
 446                 int last_errno = errno;
 447                 error("unable to resolve reference %s: %s",
 448                         orig_ref, strerror(errno));
 449                 unlock_ref(lock);
 450                 errno = last_errno;
 451                 return NULL;
 452         }
 453         lock->lk = xcalloc(1, sizeof(struct lock_file));
 454
 455         lock->ref_name = xstrdup(ref);
 456         lock->log_file = xstrdup(git_path("logs/%s", ref));
 457         ref_file = git_path(ref);
 458         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 459
 460         if (safe_create_leading_directories(ref_file))
 461                 die("unable to create directory for %s", ref_file);
 462         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 463
 464         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 465 }
 466
 467 struct ref_lock *lock_ref_sha1(const char *ref,
 468         const unsigned char *old_sha1, int mustexist)
 469 {
 470         char refpath[PATH_MAX];
 471         if (check_ref_format(ref))
 472                 return NULL;
 473         strcpy(refpath, mkpath("refs/%s", ref));
 474         return lock_ref_sha1_basic(refpath, strlen(refpath),
 475                 old_sha1, mustexist);
 476 }
 477
 478 struct ref_lock *lock_any_ref_for_update(const char *ref,
 479         const unsigned char *old_sha1, int mustexist)
 480 {
 481         return lock_ref_sha1_basic(ref, strlen(ref), old_sha1, mustexist);
 482 }
 483
 484 void unlock_ref(struct ref_lock *lock)
 485 {
 486         if (lock->lock_fd >= 0) {
 487                 close(lock->lock_fd);
 488                 /* Do not free lock->lk -- atexit() still looks at them */
 489                 if (lock->lk)
 490                         rollback_lock_file(lock->lk);
 491         }
 492         free(lock->ref_name);
 493         free(lock->log_file);
 494         free(lock);
 495 }
 496
 497 static int log_ref_write(struct ref_lock *lock,
 498         const unsigned char *sha1, const char *msg)
 499 {
 500         int logfd, written, oflags = O_APPEND | O_WRONLY;
 501         unsigned maxlen, len;
 502         char *logrec;
 503         const char *committer;
 504
 505         if (log_all_ref_updates) {
 506                 if (safe_create_leading_directories(lock->log_file) < 0)
 507                         return error("unable to create directory for %s",
 508                                 lock->log_file);
 509                 oflags |= O_CREAT;
 510         }
 511
 512         logfd = open(lock->log_file, oflags, 0666);
 513         if (logfd < 0) {
 514                 if (!log_all_ref_updates && errno == ENOENT)
 515                         return 0;
 516                 return error("Unable to append to %s: %s",
 517                         lock->log_file, strerror(errno));
 518         }
 519
 520         committer = git_committer_info(1);
 521         if (msg) {
 522                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 523                 logrec = xmalloc(maxlen);
 524                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 525                         sha1_to_hex(lock->old_sha1),
 526                         sha1_to_hex(sha1),
 527                         committer,
 528                         msg);
 529         }
 530         else {
 531                 maxlen = strlen(committer) + 2*40 + 4;
 532                 logrec = xmalloc(maxlen);
 533                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 534                         sha1_to_hex(lock->old_sha1),
 535                         sha1_to_hex(sha1),
 536                         committer);
 537         }
 538         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 539         free(logrec);
 540         close(logfd);
 541         if (written != len)
 542                 return error("Unable to append to %s", lock->log_file);
 543         return 0;
 544 }
 545
 546 int write_ref_sha1(struct ref_lock *lock,
 547         const unsigned char *sha1, const char *logmsg)
 548 {
 549         static char term = '\n';
 550
 551         if (!lock)
 552                 return -1;
 553         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 554                 unlock_ref(lock);
 555                 return 0;
 556         }
 557         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 558             write(lock->lock_fd, &term, 1) != 1
 559                 || close(lock->lock_fd) < 0) {
 560                 error("Couldn't write %s", lock->lk->filename);
 561                 unlock_ref(lock);
 562                 return -1;
 563         }
 564         if (log_ref_write(lock, sha1, logmsg) < 0) {
 565                 unlock_ref(lock);
 566                 return -1;
 567         }
 568         if (commit_lock_file(lock->lk)) {
 569                 error("Couldn't set %s", lock->ref_name);
 570                 unlock_ref(lock);
 571                 return -1;
 572         }
 573         lock->lock_fd = -1;
 574         unlock_ref(lock);
 575         return 0;
 576 }
 577
 578 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 579 {
 580         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 581         char *tz_c;
 582         int logfd, tz;
 583         struct stat st;
 584         unsigned long date;
 585         unsigned char logged_sha1[20];
 586
 587         logfile = git_path("logs/%s", ref);
 588         logfd = open(logfile, O_RDONLY, 0);
 589         if (logfd < 0)
 590                 die("Unable to read log %s: %s", logfile, strerror(errno));
 591         fstat(logfd, &st);
 592         if (!st.st_size)
 593                 die("Log %s is empty.", logfile);
 594         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 595         close(logfd);
 596
 597         lastrec = NULL;
 598         rec = logend = logdata + st.st_size;
 599         while (logdata < rec) {
 600                 if (logdata < rec && *(rec-1) == '\n')
 601                         rec--;
 602                 lastgt = NULL;
 603                 while (logdata < rec && *(rec-1) != '\n') {
 604                         rec--;
 605                         if (*rec == '>')
 606                                 lastgt = rec;
 607                 }
 608                 if (!lastgt)
 609                         die("Log %s is corrupt.", logfile);
 610                 date = strtoul(lastgt + 1, &tz_c, 10);
 611                 if (date <= at_time) {
 612                         if (lastrec) {
 613                                 if (get_sha1_hex(lastrec, logged_sha1))
 614                                         die("Log %s is corrupt.", logfile);
 615                                 if (get_sha1_hex(rec + 41, sha1))
 616                                         die("Log %s is corrupt.", logfile);
 617                                 if (hashcmp(logged_sha1, sha1)) {
 618                                         tz = strtoul(tz_c, NULL, 10);
 619                                         fprintf(stderr,
 620                                                 "warning: Log %s has gap after %s.\n",
 621                                                 logfile, show_rfc2822_date(date, tz));
 622                                 }
 623                         }
 624                         else if (date == at_time) {
 625                                 if (get_sha1_hex(rec + 41, sha1))
 626                                         die("Log %s is corrupt.", logfile);
 627                         }
 628                         else {
 629                                 if (get_sha1_hex(rec + 41, logged_sha1))
 630                                         die("Log %s is corrupt.", logfile);
 631                                 if (hashcmp(logged_sha1, sha1)) {
 632                                         tz = strtoul(tz_c, NULL, 10);
 633                                         fprintf(stderr,
 634                                                 "warning: Log %s unexpectedly ended on %s.\n",
 635                                                 logfile, show_rfc2822_date(date, tz));
 636                                 }
 637                         }
 638                         munmap((void*)logdata, st.st_size);
 639                         return 0;
 640                 }
 641                 lastrec = rec;
 642         }
 643
 644         rec = logdata;
 645         while (rec < logend && *rec != '>' && *rec != '\n')
 646                 rec++;
 647         if (rec == logend || *rec == '\n')
 648                 die("Log %s is corrupt.", logfile);
 649         date = strtoul(rec + 1, &tz_c, 10);
 650         tz = strtoul(tz_c, NULL, 10);
 651         if (get_sha1_hex(logdata, sha1))
 652                 die("Log %s is corrupt.", logfile);
 653         munmap((void*)logdata, st.st_size);
 654         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 655                 logfile, show_rfc2822_date(date, tz));
 656         return 0;
 657 }