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 flag; /* ISSYMREF? ISPACKED? */
   9         unsigned char sha1[20];
  10         char name[FLEX_ARRAY];
  11 };
  12
  13 static const char *parse_ref_line(char *line, unsigned char *sha1)
  14 {
  15         /*
  16          * 42: the answer to everything.
  17          *
  18          * In this case, it happens to be the answer to
  19          *  40 (length of sha1 hex representation)
  20          *  +1 (space in between hex and name)
  21          *  +1 (newline at the end of the line)
  22          */
  23         int len = strlen(line) - 42;
  24
  25         if (len <= 0)
  26                 return NULL;
  27         if (get_sha1_hex(line, sha1) < 0)
  28                 return NULL;
  29         if (!isspace(line[40]))
  30                 return NULL;
  31         line += 41;
  32         if (isspace(*line))
  33                 return NULL;
  34         if (line[len] != '\n')
  35                 return NULL;
  36         line[len] = 0;
  37         return line;
  38 }
  39
  40 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  41                                 int flag, struct ref_list *list)
  42 {
  43         int len;
  44         struct ref_list **p = &list, *entry;
  45
  46         /* Find the place to insert the ref into.. */
  47         while ((entry = *p) != NULL) {
  48                 int cmp = strcmp(entry->name, name);
  49                 if (cmp > 0)
  50                         break;
  51
  52                 /* Same as existing entry? */
  53                 if (!cmp)
  54                         return list;
  55                 p = &entry->next;
  56         }
  57
  58         /* Allocate it and add it in.. */
  59         len = strlen(name) + 1;
  60         entry = xmalloc(sizeof(struct ref_list) + len);
  61         hashcpy(entry->sha1, sha1);
  62         memcpy(entry->name, name, len);
  63         entry->flag = flag;
  64         entry->next = *p;
  65         *p = entry;
  66         return list;
  67 }
  68
  69 static struct ref_list *get_packed_refs(void)
  70 {
  71         static int did_refs = 0;
  72         static struct ref_list *refs = NULL;
  73
  74         if (!did_refs) {
  75                 FILE *f = fopen(git_path("packed-refs"), "r");
  76                 if (f) {
  77                         struct ref_list *list = NULL;
  78                         char refline[PATH_MAX];
  79                         while (fgets(refline, sizeof(refline), f)) {
  80                                 unsigned char sha1[20];
  81                                 const char *name = parse_ref_line(refline, sha1);
  82                                 if (!name)
  83                                         continue;
  84                                 list = add_ref(name, sha1, REF_ISPACKED, list);
  85                         }
  86                         fclose(f);
  87                         refs = list;
  88                 }
  89                 did_refs = 1;
  90         }
  91         return refs;
  92 }
  93
  94 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
  95 {
  96         DIR *dir = opendir(git_path("%s", base));
  97
  98         if (dir) {
  99                 struct dirent *de;
 100                 int baselen = strlen(base);
 101                 char *ref = xmalloc(baselen + 257);
 102
 103                 memcpy(ref, base, baselen);
 104                 if (baselen && base[baselen-1] != '/')
 105                         ref[baselen++] = '/';
 106
 107                 while ((de = readdir(dir)) != NULL) {
 108                         unsigned char sha1[20];
 109                         struct stat st;
 110                         int flag;
 111                         int namelen;
 112
 113                         if (de->d_name[0] == '.')
 114                                 continue;
 115                         namelen = strlen(de->d_name);
 116                         if (namelen > 255)
 117                                 continue;
 118                         if (has_extension(de->d_name, ".lock"))
 119                                 continue;
 120                         memcpy(ref + baselen, de->d_name, namelen+1);
 121                         if (stat(git_path("%s", ref), &st) < 0)
 122                                 continue;
 123                         if (S_ISDIR(st.st_mode)) {
 124                                 list = get_ref_dir(ref, list);
 125                                 continue;
 126                         }
 127                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 128                                 error("%s points nowhere!", ref);
 129                                 continue;
 130                         }
 131                         list = add_ref(ref, sha1, flag, list);
 132                 }
 133                 free(ref);
 134                 closedir(dir);
 135         }
 136         return list;
 137 }
 138
 139 static struct ref_list *get_loose_refs(void)
 140 {
 141         static int did_refs = 0;
 142         static struct ref_list *refs = NULL;
 143
 144         if (!did_refs) {
 145                 refs = get_ref_dir("refs", NULL);
 146                 did_refs = 1;
 147         }
 148         return refs;
 149 }
 150
 151 /* We allow "recursive" symbolic refs. Only within reason, though */
 152 #define MAXDEPTH 5
 153
 154 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 155 {
 156         int depth = MAXDEPTH, len;
 157         char buffer[256];
 158         static char ref_buffer[256];
 159
 160         if (flag)
 161                 *flag = 0;
 162
 163         for (;;) {
 164                 const char *path = git_path("%s", ref);
 165                 struct stat st;
 166                 char *buf;
 167                 int fd;
 168
 169                 if (--depth < 0)
 170                         return NULL;
 171
 172                 /* Special case: non-existing file.
 173                  * Not having the refs/heads/new-branch is OK
 174                  * if we are writing into it, so is .git/HEAD
 175                  * that points at refs/heads/master still to be
 176                  * born.  It is NOT OK if we are resolving for
 177                  * reading.
 178                  */
 179                 if (lstat(path, &st) < 0) {
 180                         struct ref_list *list = get_packed_refs();
 181                         while (list) {
 182                                 if (!strcmp(ref, list->name)) {
 183                                         hashcpy(sha1, list->sha1);
 184                                         if (flag)
 185                                                 *flag |= REF_ISPACKED;
 186                                         return ref;
 187                                 }
 188                                 list = list->next;
 189                         }
 190                         if (reading || errno != ENOENT)
 191                                 return NULL;
 192                         hashclr(sha1);
 193                         return ref;
 194                 }
 195
 196                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 197                 if (S_ISLNK(st.st_mode)) {
 198                         len = readlink(path, buffer, sizeof(buffer)-1);
 199                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 200                                 buffer[len] = 0;
 201                                 strcpy(ref_buffer, buffer);
 202                                 ref = ref_buffer;
 203                                 if (flag)
 204                                         *flag |= REF_ISSYMREF;
 205                                 continue;
 206                         }
 207                 }
 208
 209                 /*
 210                  * Anything else, just open it and try to use it as
 211                  * a ref
 212                  */
 213                 fd = open(path, O_RDONLY);
 214                 if (fd < 0)
 215                         return NULL;
 216                 len = read(fd, buffer, sizeof(buffer)-1);
 217                 close(fd);
 218
 219                 /*
 220                  * Is it a symbolic ref?
 221                  */
 222                 if (len < 4 || memcmp("ref:", buffer, 4))
 223                         break;
 224                 buf = buffer + 4;
 225                 len -= 4;
 226                 while (len && isspace(*buf))
 227                         buf++, len--;
 228                 while (len && isspace(buf[len-1]))
 229                         len--;
 230                 buf[len] = 0;
 231                 memcpy(ref_buffer, buf, len + 1);
 232                 ref = ref_buffer;
 233                 if (flag)
 234                         *flag |= REF_ISSYMREF;
 235         }
 236         if (len < 40 || get_sha1_hex(buffer, sha1))
 237                 return NULL;
 238         return ref;
 239 }
 240
 241 int create_symref(const char *ref_target, const char *refs_heads_master)
 242 {
 243         const char *lockpath;
 244         char ref[1000];
 245         int fd, len, written;
 246         const char *git_HEAD = git_path("%s", ref_target);
 247
 248 #ifndef NO_SYMLINK_HEAD
 249         if (prefer_symlink_refs) {
 250                 unlink(git_HEAD);
 251                 if (!symlink(refs_heads_master, git_HEAD))
 252                         return 0;
 253                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 254         }
 255 #endif
 256
 257         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 258         if (sizeof(ref) <= len) {
 259                 error("refname too long: %s", refs_heads_master);
 260                 return -1;
 261         }
 262         lockpath = mkpath("%s.lock", git_HEAD);
 263         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 264         written = write(fd, ref, len);
 265         close(fd);
 266         if (written != len) {
 267                 unlink(lockpath);
 268                 error("Unable to write to %s", lockpath);
 269                 return -2;
 270         }
 271         if (rename(lockpath, git_HEAD) < 0) {
 272                 unlink(lockpath);
 273                 error("Unable to create %s", git_HEAD);
 274                 return -3;
 275         }
 276         if (adjust_shared_perm(git_HEAD)) {
 277                 unlink(lockpath);
 278                 error("Unable to fix permissions on %s", lockpath);
 279                 return -4;
 280         }
 281         return 0;
 282 }
 283
 284 int read_ref(const char *ref, unsigned char *sha1)
 285 {
 286         if (resolve_ref(ref, sha1, 1, NULL))
 287                 return 0;
 288         return -1;
 289 }
 290
 291 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 292                            void *cb_data)
 293 {
 294         int retval;
 295         struct ref_list *packed = get_packed_refs();
 296         struct ref_list *loose = get_loose_refs();
 297
 298         while (packed && loose) {
 299                 struct ref_list *entry;
 300                 int cmp = strcmp(packed->name, loose->name);
 301                 if (!cmp) {
 302                         packed = packed->next;
 303                         continue;
 304                 }
 305                 if (cmp > 0) {
 306                         entry = loose;
 307                         loose = loose->next;
 308                 } else {
 309                         entry = packed;
 310                         packed = packed->next;
 311                 }
 312                 if (strncmp(base, entry->name, trim))
 313                         continue;
 314                 if (is_null_sha1(entry->sha1))
 315                         continue;
 316                 if (!has_sha1_file(entry->sha1)) {
 317                         error("%s does not point to a valid object!", entry->name);
 318                         continue;
 319                 }
 320                 retval = fn(entry->name + trim, entry->sha1,
 321                             entry->flag, cb_data);
 322                 if (retval)
 323                         return retval;
 324         }
 325
 326         packed = packed ? packed : loose;
 327         while (packed) {
 328                 if (!strncmp(base, packed->name, trim)) {
 329                         retval = fn(packed->name + trim, packed->sha1,
 330                                     packed->flag, cb_data);
 331                         if (retval)
 332                                 return retval;
 333                 }
 334                 packed = packed->next;
 335         }
 336         return 0;
 337 }
 338
 339 int head_ref(each_ref_fn fn, void *cb_data)
 340 {
 341         unsigned char sha1[20];
 342         int flag;
 343
 344         if (resolve_ref("HEAD", sha1, 1, &flag))
 345                 return fn("HEAD", sha1, flag, cb_data);
 346         return 0;
 347 }
 348
 349 int for_each_ref(each_ref_fn fn, void *cb_data)
 350 {
 351         return do_for_each_ref("refs/", fn, 0, cb_data);
 352 }
 353
 354 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 355 {
 356         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 357 }
 358
 359 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 360 {
 361         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 362 }
 363
 364 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 365 {
 366         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 367 }
 368
 369 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 370  * caller should do resolve_ref or read_ref like everybody else.  Or
 371  * maybe everybody else should use get_ref_sha1() instead of doing
 372  * read_ref().
 373  */
 374 int get_ref_sha1(const char *ref, unsigned char *sha1)
 375 {
 376         if (check_ref_format(ref))
 377                 return -1;
 378         return read_ref(mkpath("refs/%s", ref), sha1);
 379 }
 380
 381 /*
 382  * Make sure "ref" is something reasonable to have under ".git/refs/";
 383  * We do not like it if:
 384  *
 385  * - any path component of it begins with ".", or
 386  * - it has double dots "..", or
 387  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 388  * - it ends with a "/".
 389  */
 390
 391 static inline int bad_ref_char(int ch)
 392 {
 393         return (((unsigned) ch) <= ' ' ||
 394                 ch == '~' || ch == '^' || ch == ':' ||
 395                 /* 2.13 Pattern Matching Notation */
 396                 ch == '?' || ch == '*' || ch == '[');
 397 }
 398
 399 int check_ref_format(const char *ref)
 400 {
 401         int ch, level;
 402         const char *cp = ref;
 403
 404         level = 0;
 405         while (1) {
 406                 while ((ch = *cp++) == '/')
 407                         ; /* tolerate duplicated slashes */
 408                 if (!ch)
 409                         return -1; /* should not end with slashes */
 410
 411                 /* we are at the beginning of the path component */
 412                 if (ch == '.' || bad_ref_char(ch))
 413                         return -1;
 414
 415                 /* scan the rest of the path component */
 416                 while ((ch = *cp++) != 0) {
 417                         if (bad_ref_char(ch))
 418                                 return -1;
 419                         if (ch == '/')
 420                                 break;
 421                         if (ch == '.' && *cp == '.')
 422                                 return -1;
 423                 }
 424                 level++;
 425                 if (!ch) {
 426                         if (level < 2)
 427                                 return -1; /* at least of form "heads/blah" */
 428                         return 0;
 429                 }
 430         }
 431 }
 432
 433 static struct ref_lock *verify_lock(struct ref_lock *lock,
 434         const unsigned char *old_sha1, int mustexist)
 435 {
 436         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 437                 error("Can't verify ref %s", lock->ref_name);
 438                 unlock_ref(lock);
 439                 return NULL;
 440         }
 441         if (hashcmp(lock->old_sha1, old_sha1)) {
 442                 error("Ref %s is at %s but expected %s", lock->ref_name,
 443                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 444                 unlock_ref(lock);
 445                 return NULL;
 446         }
 447         return lock;
 448 }
 449
 450 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1)
 451 {
 452         char *ref_file;
 453         const char *orig_ref = ref;
 454         struct ref_lock *lock;
 455         struct stat st;
 456         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 457
 458         lock = xcalloc(1, sizeof(struct ref_lock));
 459         lock->lock_fd = -1;
 460
 461         ref = resolve_ref(ref, lock->old_sha1, mustexist, NULL);
 462         if (!ref) {
 463                 int last_errno = errno;
 464                 error("unable to resolve reference %s: %s",
 465                         orig_ref, strerror(errno));
 466                 unlock_ref(lock);
 467                 errno = last_errno;
 468                 return NULL;
 469         }
 470         lock->lk = xcalloc(1, sizeof(struct lock_file));
 471
 472         lock->ref_name = xstrdup(ref);
 473         lock->log_file = xstrdup(git_path("logs/%s", ref));
 474         ref_file = git_path("%s", ref);
 475         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 476
 477         if (safe_create_leading_directories(ref_file))
 478                 die("unable to create directory for %s", ref_file);
 479         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 480
 481         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 482 }
 483
 484 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 485 {
 486         char refpath[PATH_MAX];
 487         if (check_ref_format(ref))
 488                 return NULL;
 489         strcpy(refpath, mkpath("refs/%s", ref));
 490         return lock_ref_sha1_basic(refpath, old_sha1);
 491 }
 492
 493 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 494 {
 495         return lock_ref_sha1_basic(ref, old_sha1);
 496 }
 497
 498 void unlock_ref(struct ref_lock *lock)
 499 {
 500         if (lock->lock_fd >= 0) {
 501                 close(lock->lock_fd);
 502                 /* Do not free lock->lk -- atexit() still looks at them */
 503                 if (lock->lk)
 504                         rollback_lock_file(lock->lk);
 505         }
 506         free(lock->ref_name);
 507         free(lock->log_file);
 508         free(lock);
 509 }
 510
 511 static int log_ref_write(struct ref_lock *lock,
 512         const unsigned char *sha1, const char *msg)
 513 {
 514         int logfd, written, oflags = O_APPEND | O_WRONLY;
 515         unsigned maxlen, len;
 516         char *logrec;
 517         const char *committer;
 518
 519         if (log_all_ref_updates) {
 520                 if (safe_create_leading_directories(lock->log_file) < 0)
 521                         return error("unable to create directory for %s",
 522                                 lock->log_file);
 523                 oflags |= O_CREAT;
 524         }
 525
 526         logfd = open(lock->log_file, oflags, 0666);
 527         if (logfd < 0) {
 528                 if (!log_all_ref_updates && errno == ENOENT)
 529                         return 0;
 530                 return error("Unable to append to %s: %s",
 531                         lock->log_file, strerror(errno));
 532         }
 533
 534         committer = git_committer_info(1);
 535         if (msg) {
 536                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 537                 logrec = xmalloc(maxlen);
 538                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 539                         sha1_to_hex(lock->old_sha1),
 540                         sha1_to_hex(sha1),
 541                         committer,
 542                         msg);
 543         }
 544         else {
 545                 maxlen = strlen(committer) + 2*40 + 4;
 546                 logrec = xmalloc(maxlen);
 547                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 548                         sha1_to_hex(lock->old_sha1),
 549                         sha1_to_hex(sha1),
 550                         committer);
 551         }
 552         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 553         free(logrec);
 554         close(logfd);
 555         if (written != len)
 556                 return error("Unable to append to %s", lock->log_file);
 557         return 0;
 558 }
 559
 560 int write_ref_sha1(struct ref_lock *lock,
 561         const unsigned char *sha1, const char *logmsg)
 562 {
 563         static char term = '\n';
 564
 565         if (!lock)
 566                 return -1;
 567         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 568                 unlock_ref(lock);
 569                 return 0;
 570         }
 571         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 572             write(lock->lock_fd, &term, 1) != 1
 573                 || close(lock->lock_fd) < 0) {
 574                 error("Couldn't write %s", lock->lk->filename);
 575                 unlock_ref(lock);
 576                 return -1;
 577         }
 578         if (log_ref_write(lock, sha1, logmsg) < 0) {
 579                 unlock_ref(lock);
 580                 return -1;
 581         }
 582         if (commit_lock_file(lock->lk)) {
 583                 error("Couldn't set %s", lock->ref_name);
 584                 unlock_ref(lock);
 585                 return -1;
 586         }
 587         lock->lock_fd = -1;
 588         unlock_ref(lock);
 589         return 0;
 590 }
 591
 592 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 593 {
 594         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 595         char *tz_c;
 596         int logfd, tz;
 597         struct stat st;
 598         unsigned long date;
 599         unsigned char logged_sha1[20];
 600
 601         logfile = git_path("logs/%s", ref);
 602         logfd = open(logfile, O_RDONLY, 0);
 603         if (logfd < 0)
 604                 die("Unable to read log %s: %s", logfile, strerror(errno));
 605         fstat(logfd, &st);
 606         if (!st.st_size)
 607                 die("Log %s is empty.", logfile);
 608         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 609         close(logfd);
 610
 611         lastrec = NULL;
 612         rec = logend = logdata + st.st_size;
 613         while (logdata < rec) {
 614                 if (logdata < rec && *(rec-1) == '\n')
 615                         rec--;
 616                 lastgt = NULL;
 617                 while (logdata < rec && *(rec-1) != '\n') {
 618                         rec--;
 619                         if (*rec == '>')
 620                                 lastgt = rec;
 621                 }
 622                 if (!lastgt)
 623                         die("Log %s is corrupt.", logfile);
 624                 date = strtoul(lastgt + 1, &tz_c, 10);
 625                 if (date <= at_time) {
 626                         if (lastrec) {
 627                                 if (get_sha1_hex(lastrec, logged_sha1))
 628                                         die("Log %s is corrupt.", logfile);
 629                                 if (get_sha1_hex(rec + 41, 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 has gap after %s.\n",
 635                                                 logfile, show_rfc2822_date(date, tz));
 636                                 }
 637                         }
 638                         else if (date == at_time) {
 639                                 if (get_sha1_hex(rec + 41, sha1))
 640                                         die("Log %s is corrupt.", logfile);
 641                         }
 642                         else {
 643                                 if (get_sha1_hex(rec + 41, logged_sha1))
 644                                         die("Log %s is corrupt.", logfile);
 645                                 if (hashcmp(logged_sha1, sha1)) {
 646                                         tz = strtoul(tz_c, NULL, 10);
 647                                         fprintf(stderr,
 648                                                 "warning: Log %s unexpectedly ended on %s.\n",
 649                                                 logfile, show_rfc2822_date(date, tz));
 650                                 }
 651                         }
 652                         munmap((void*)logdata, st.st_size);
 653                         return 0;
 654                 }
 655                 lastrec = rec;
 656         }
 657
 658         rec = logdata;
 659         while (rec < logend && *rec != '>' && *rec != '\n')
 660                 rec++;
 661         if (rec == logend || *rec == '\n')
 662                 die("Log %s is corrupt.", logfile);
 663         date = strtoul(rec + 1, &tz_c, 10);
 664         tz = strtoul(tz_c, NULL, 10);
 665         if (get_sha1_hex(logdata, sha1))
 666                 die("Log %s is corrupt.", logfile);
 667         munmap((void*)logdata, st.st_size);
 668         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 669                 logfile, show_rfc2822_date(date, tz));
 670         return 0;
 671 }