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 *ref = xmalloc(baselen + 257);
  97
  98                 memcpy(ref, base, baselen);
  99                 if (baselen && base[baselen-1] != '/')
 100                         ref[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(ref + baselen, de->d_name, namelen+1);
 115                         if (stat(git_path("%s", ref), &st) < 0)
 116                                 continue;
 117                         if (S_ISDIR(st.st_mode)) {
 118                                 list = get_ref_dir(ref, list);
 119                                 continue;
 120                         }
 121                         if (read_ref(ref, sha1) < 0) {
 122                                 error("%s points nowhere!", ref);
 123                                 continue;
 124                         }
 125                         list = add_ref(ref, sha1, list);
 126                 }
 127                 free(ref);
 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 *ref, unsigned char *sha1, int reading)
 149 {
 150         int depth = MAXDEPTH, len;
 151         char buffer[256];
 152         static char ref_buffer[256];
 153
 154         for (;;) {
 155                 const char *path = git_path("%s", ref);
 156                 struct stat st;
 157                 char *buf;
 158                 int fd;
 159
 160                 if (--depth < 0)
 161                         return NULL;
 162
 163                 /* Special case: non-existing file.
 164                  * Not having the refs/heads/new-branch is OK
 165                  * if we are writing into it, so is .git/HEAD
 166                  * that points at refs/heads/master still to be
 167                  * born.  It is NOT OK if we are resolving for
 168                  * reading.
 169                  */
 170                 if (lstat(path, &st) < 0) {
 171                         if (reading || errno != ENOENT)
 172                                 return NULL;
 173                         hashclr(sha1);
 174                         return ref;
 175                 }
 176
 177                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 178                 if (S_ISLNK(st.st_mode)) {
 179                         len = readlink(path, buffer, sizeof(buffer)-1);
 180                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 181                                 buffer[len] = 0;
 182                                 strcpy(ref_buffer, buffer);
 183                                 ref = ref_buffer;
 184                                 continue;
 185                         }
 186                 }
 187
 188                 /*
 189                  * Anything else, just open it and try to use it as
 190                  * a ref
 191                  */
 192                 fd = open(path, O_RDONLY);
 193                 if (fd < 0)
 194                         return NULL;
 195                 len = read(fd, buffer, sizeof(buffer)-1);
 196                 close(fd);
 197
 198                 /*
 199                  * Is it a symbolic ref?
 200                  */
 201                 if (len < 4 || memcmp("ref:", buffer, 4))
 202                         break;
 203                 buf = buffer + 4;
 204                 len -= 4;
 205                 while (len && isspace(*buf))
 206                         buf++, len--;
 207                 while (len && isspace(buf[len-1]))
 208                         len--;
 209                 buf[len] = 0;
 210                 memcpy(ref_buffer, buf, len + 1);
 211                 ref = ref_buffer;
 212         }
 213         if (len < 40 || get_sha1_hex(buffer, sha1))
 214                 return NULL;
 215         return ref;
 216 }
 217
 218 int create_symref(const char *ref_target, const char *refs_heads_master)
 219 {
 220         const char *lockpath;
 221         char ref[1000];
 222         int fd, len, written;
 223         const char *git_HEAD = git_path("%s", ref_target);
 224
 225 #ifndef NO_SYMLINK_HEAD
 226         if (prefer_symlink_refs) {
 227                 unlink(git_HEAD);
 228                 if (!symlink(refs_heads_master, git_HEAD))
 229                         return 0;
 230                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 231         }
 232 #endif
 233
 234         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 235         if (sizeof(ref) <= len) {
 236                 error("refname too long: %s", refs_heads_master);
 237                 return -1;
 238         }
 239         lockpath = mkpath("%s.lock", git_HEAD);
 240         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 241         written = write(fd, ref, len);
 242         close(fd);
 243         if (written != len) {
 244                 unlink(lockpath);
 245                 error("Unable to write to %s", lockpath);
 246                 return -2;
 247         }
 248         if (rename(lockpath, git_HEAD) < 0) {
 249                 unlink(lockpath);
 250                 error("Unable to create %s", git_HEAD);
 251                 return -3;
 252         }
 253         if (adjust_shared_perm(git_HEAD)) {
 254                 unlink(lockpath);
 255                 error("Unable to fix permissions on %s", lockpath);
 256                 return -4;
 257         }
 258         return 0;
 259 }
 260
 261 int read_ref(const char *ref, unsigned char *sha1)
 262 {
 263         if (resolve_ref(ref, sha1, 1))
 264                 return 0;
 265         return -1;
 266 }
 267
 268 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 269 {
 270         int retval;
 271         struct ref_list *packed = get_packed_refs();
 272         struct ref_list *loose = get_loose_refs();
 273
 274         while (packed && loose) {
 275                 struct ref_list *entry;
 276                 int cmp = strcmp(packed->name, loose->name);
 277                 if (!cmp) {
 278                         packed = packed->next;
 279                         continue;
 280                 }
 281                 if (cmp > 0) {
 282                         entry = loose;
 283                         loose = loose->next;
 284                 } else {
 285                         entry = packed;
 286                         packed = packed->next;
 287                 }
 288                 if (strncmp(base, entry->name, trim))
 289                         continue;
 290                 if (is_null_sha1(entry->sha1))
 291                         continue;
 292                 if (!has_sha1_file(entry->sha1)) {
 293                         error("%s does not point to a valid object!", entry->name);
 294                         continue;
 295                 }
 296                 retval = fn(entry->name + trim, entry->sha1);
 297                 if (retval)
 298                         return retval;
 299         }
 300
 301         packed = packed ? packed : loose;
 302         while (packed) {
 303                 if (!strncmp(base, packed->name, trim)) {
 304                         retval = fn(packed->name + trim, packed->sha1);
 305                         if (retval)
 306                                 return retval;
 307                 }
 308                 packed = packed->next;
 309         }
 310         return 0;
 311 }
 312
 313 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 314 {
 315         unsigned char sha1[20];
 316         if (!read_ref("HEAD", sha1))
 317                 return fn("HEAD", sha1);
 318         return 0;
 319 }
 320
 321 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 322 {
 323         return do_for_each_ref("refs/", fn, 0);
 324 }
 325
 326 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 327 {
 328         return do_for_each_ref("refs/tags/", fn, 10);
 329 }
 330
 331 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 332 {
 333         return do_for_each_ref("refs/heads/", fn, 11);
 334 }
 335
 336 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 337 {
 338         return do_for_each_ref("refs/remotes/", fn, 13);
 339 }
 340
 341 int get_ref_sha1(const char *ref, unsigned char *sha1)
 342 {
 343         if (check_ref_format(ref))
 344                 return -1;
 345         return read_ref(mkpath("refs/%s", ref), sha1);
 346 }
 347
 348 /*
 349  * Make sure "ref" is something reasonable to have under ".git/refs/";
 350  * We do not like it if:
 351  *
 352  * - any path component of it begins with ".", or
 353  * - it has double dots "..", or
 354  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 355  * - it ends with a "/".
 356  */
 357
 358 static inline int bad_ref_char(int ch)
 359 {
 360         return (((unsigned) ch) <= ' ' ||
 361                 ch == '~' || ch == '^' || ch == ':' ||
 362                 /* 2.13 Pattern Matching Notation */
 363                 ch == '?' || ch == '*' || ch == '[');
 364 }
 365
 366 int check_ref_format(const char *ref)
 367 {
 368         int ch, level;
 369         const char *cp = ref;
 370
 371         level = 0;
 372         while (1) {
 373                 while ((ch = *cp++) == '/')
 374                         ; /* tolerate duplicated slashes */
 375                 if (!ch)
 376                         return -1; /* should not end with slashes */
 377
 378                 /* we are at the beginning of the path component */
 379                 if (ch == '.' || bad_ref_char(ch))
 380                         return -1;
 381
 382                 /* scan the rest of the path component */
 383                 while ((ch = *cp++) != 0) {
 384                         if (bad_ref_char(ch))
 385                                 return -1;
 386                         if (ch == '/')
 387                                 break;
 388                         if (ch == '.' && *cp == '.')
 389                                 return -1;
 390                 }
 391                 level++;
 392                 if (!ch) {
 393                         if (level < 2)
 394                                 return -1; /* at least of form "heads/blah" */
 395                         return 0;
 396                 }
 397         }
 398 }
 399
 400 static struct ref_lock *verify_lock(struct ref_lock *lock,
 401         const unsigned char *old_sha1, int mustexist)
 402 {
 403         char buf[40];
 404         int nr, fd = open(lock->ref_file, O_RDONLY);
 405         if (fd < 0 && (mustexist || errno != ENOENT)) {
 406                 error("Can't verify ref %s", lock->ref_file);
 407                 unlock_ref(lock);
 408                 return NULL;
 409         }
 410         nr = read(fd, buf, 40);
 411         close(fd);
 412         if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 413                 error("Can't verify ref %s", lock->ref_file);
 414                 unlock_ref(lock);
 415                 return NULL;
 416         }
 417         if (hashcmp(lock->old_sha1, old_sha1)) {
 418                 error("Ref %s is at %s but expected %s", lock->ref_file,
 419                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 420                 unlock_ref(lock);
 421                 return NULL;
 422         }
 423         return lock;
 424 }
 425
 426 static struct ref_lock *lock_ref_sha1_basic(const char *ref,
 427         int plen,
 428         const unsigned char *old_sha1, int mustexist)
 429 {
 430         const char *orig_ref = ref;
 431         struct ref_lock *lock;
 432         struct stat st;
 433
 434         lock = xcalloc(1, sizeof(struct ref_lock));
 435         lock->lock_fd = -1;
 436
 437         ref = resolve_ref(ref, lock->old_sha1, mustexist);
 438         if (!ref) {
 439                 int last_errno = errno;
 440                 error("unable to resolve reference %s: %s",
 441                         orig_ref, strerror(errno));
 442                 unlock_ref(lock);
 443                 errno = last_errno;
 444                 return NULL;
 445         }
 446         lock->lk = xcalloc(1, sizeof(struct lock_file));
 447
 448         lock->ref_file = xstrdup(git_path("%s", ref));
 449         lock->log_file = xstrdup(git_path("logs/%s", ref));
 450         lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 451
 452         if (safe_create_leading_directories(lock->ref_file))
 453                 die("unable to create directory for %s", lock->ref_file);
 454         lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 455
 456         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 457 }
 458
 459 struct ref_lock *lock_ref_sha1(const char *ref,
 460         const unsigned char *old_sha1, int mustexist)
 461 {
 462         if (check_ref_format(ref))
 463                 return NULL;
 464         return lock_ref_sha1_basic(mkpath("refs/%s", ref),
 465                 5 + strlen(ref), old_sha1, mustexist);
 466 }
 467
 468 struct ref_lock *lock_any_ref_for_update(const char *ref,
 469         const unsigned char *old_sha1, int mustexist)
 470 {
 471         return lock_ref_sha1_basic(ref, strlen(ref), old_sha1, mustexist);
 472 }
 473
 474 void unlock_ref(struct ref_lock *lock)
 475 {
 476         if (lock->lock_fd >= 0) {
 477                 close(lock->lock_fd);
 478                 /* Do not free lock->lk -- atexit() still looks at them */
 479                 if (lock->lk)
 480                         rollback_lock_file(lock->lk);
 481         }
 482         free(lock->ref_file);
 483         free(lock->log_file);
 484         free(lock);
 485 }
 486
 487 static int log_ref_write(struct ref_lock *lock,
 488         const unsigned char *sha1, const char *msg)
 489 {
 490         int logfd, written, oflags = O_APPEND | O_WRONLY;
 491         unsigned maxlen, len;
 492         char *logrec;
 493         const char *committer;
 494
 495         if (log_all_ref_updates) {
 496                 if (safe_create_leading_directories(lock->log_file) < 0)
 497                         return error("unable to create directory for %s",
 498                                 lock->log_file);
 499                 oflags |= O_CREAT;
 500         }
 501
 502         logfd = open(lock->log_file, oflags, 0666);
 503         if (logfd < 0) {
 504                 if (!log_all_ref_updates && errno == ENOENT)
 505                         return 0;
 506                 return error("Unable to append to %s: %s",
 507                         lock->log_file, strerror(errno));
 508         }
 509
 510         committer = git_committer_info(1);
 511         if (msg) {
 512                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 513                 logrec = xmalloc(maxlen);
 514                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 515                         sha1_to_hex(lock->old_sha1),
 516                         sha1_to_hex(sha1),
 517                         committer,
 518                         msg);
 519         }
 520         else {
 521                 maxlen = strlen(committer) + 2*40 + 4;
 522                 logrec = xmalloc(maxlen);
 523                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 524                         sha1_to_hex(lock->old_sha1),
 525                         sha1_to_hex(sha1),
 526                         committer);
 527         }
 528         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 529         free(logrec);
 530         close(logfd);
 531         if (written != len)
 532                 return error("Unable to append to %s", lock->log_file);
 533         return 0;
 534 }
 535
 536 int write_ref_sha1(struct ref_lock *lock,
 537         const unsigned char *sha1, const char *logmsg)
 538 {
 539         static char term = '\n';
 540
 541         if (!lock)
 542                 return -1;
 543         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 544                 unlock_ref(lock);
 545                 return 0;
 546         }
 547         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 548             write(lock->lock_fd, &term, 1) != 1
 549                 || close(lock->lock_fd) < 0) {
 550                 error("Couldn't write %s", lock->lk->filename);
 551                 unlock_ref(lock);
 552                 return -1;
 553         }
 554         if (log_ref_write(lock, sha1, logmsg) < 0) {
 555                 unlock_ref(lock);
 556                 return -1;
 557         }
 558         if (commit_lock_file(lock->lk)) {
 559                 error("Couldn't set %s", lock->ref_file);
 560                 unlock_ref(lock);
 561                 return -1;
 562         }
 563         lock->lock_fd = -1;
 564         unlock_ref(lock);
 565         return 0;
 566 }
 567
 568 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 569 {
 570         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 571         char *tz_c;
 572         int logfd, tz;
 573         struct stat st;
 574         unsigned long date;
 575         unsigned char logged_sha1[20];
 576
 577         logfile = git_path("logs/%s", ref);
 578         logfd = open(logfile, O_RDONLY, 0);
 579         if (logfd < 0)
 580                 die("Unable to read log %s: %s", logfile, strerror(errno));
 581         fstat(logfd, &st);
 582         if (!st.st_size)
 583                 die("Log %s is empty.", logfile);
 584         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 585         close(logfd);
 586
 587         lastrec = NULL;
 588         rec = logend = logdata + st.st_size;
 589         while (logdata < rec) {
 590                 if (logdata < rec && *(rec-1) == '\n')
 591                         rec--;
 592                 lastgt = NULL;
 593                 while (logdata < rec && *(rec-1) != '\n') {
 594                         rec--;
 595                         if (*rec == '>')
 596                                 lastgt = rec;
 597                 }
 598                 if (!lastgt)
 599                         die("Log %s is corrupt.", logfile);
 600                 date = strtoul(lastgt + 1, &tz_c, 10);
 601                 if (date <= at_time) {
 602                         if (lastrec) {
 603                                 if (get_sha1_hex(lastrec, logged_sha1))
 604                                         die("Log %s is corrupt.", logfile);
 605                                 if (get_sha1_hex(rec + 41, sha1))
 606                                         die("Log %s is corrupt.", logfile);
 607                                 if (hashcmp(logged_sha1, sha1)) {
 608                                         tz = strtoul(tz_c, NULL, 10);
 609                                         fprintf(stderr,
 610                                                 "warning: Log %s has gap after %s.\n",
 611                                                 logfile, show_rfc2822_date(date, tz));
 612                                 }
 613                         }
 614                         else if (date == at_time) {
 615                                 if (get_sha1_hex(rec + 41, sha1))
 616                                         die("Log %s is corrupt.", logfile);
 617                         }
 618                         else {
 619                                 if (get_sha1_hex(rec + 41, logged_sha1))
 620                                         die("Log %s is corrupt.", logfile);
 621                                 if (hashcmp(logged_sha1, sha1)) {
 622                                         tz = strtoul(tz_c, NULL, 10);
 623                                         fprintf(stderr,
 624                                                 "warning: Log %s unexpectedly ended on %s.\n",
 625                                                 logfile, show_rfc2822_date(date, tz));
 626                                 }
 627                         }
 628                         munmap((void*)logdata, st.st_size);
 629                         return 0;
 630                 }
 631                 lastrec = rec;
 632         }
 633
 634         rec = logdata;
 635         while (rec < logend && *rec != '>' && *rec != '\n')
 636                 rec++;
 637         if (rec == logend || *rec == '\n')
 638                 die("Log %s is corrupt.", logfile);
 639         date = strtoul(rec + 1, &tz_c, 10);
 640         tz = strtoul(tz_c, NULL, 10);
 641         if (get_sha1_hex(logdata, sha1))
 642                 die("Log %s is corrupt.", logfile);
 643         munmap((void*)logdata, st.st_size);
 644         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 645                 logfile, show_rfc2822_date(date, tz));
 646         return 0;
 647 }