refs.c

   1 #include "refs.h"
   2 #include "cache.h"
   3
   4 #include <errno.h>
   5
   6 /* We allow "recursive" symbolic refs. Only within reason, though */
   7 #define MAXDEPTH 5
   8
   9 const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
  10 {
  11         int depth = MAXDEPTH, len;
  12         char buffer[256];
  13
  14         for (;;) {
  15                 struct stat st;
  16                 char *buf;
  17                 int fd;
  18
  19                 if (--depth < 0)
  20                         return NULL;
  21
  22                 /* Special case: non-existing file.
  23                  * Not having the refs/heads/new-branch is OK
  24                  * if we are writing into it, so is .git/HEAD
  25                  * that points at refs/heads/master still to be
  26                  * born.  It is NOT OK if we are resolving for
  27                  * reading.
  28                  */
  29                 if (lstat(path, &st) < 0) {
  30                         if (reading || errno != ENOENT)
  31                                 return NULL;
  32                         hashclr(sha1);
  33                         return path;
  34                 }
  35
  36                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
  37                 if (S_ISLNK(st.st_mode)) {
  38                         len = readlink(path, buffer, sizeof(buffer)-1);
  39                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
  40                                 path = git_path("%.*s", len, buffer);
  41                                 continue;
  42                         }
  43                 }
  44
  45                 /* Is it a directory? */
  46                 if (S_ISDIR(st.st_mode)) {
  47                         errno = EISDIR;
  48                         return NULL;
  49                 }
  50
  51                 /*
  52                  * Anything else, just open it and try to use it as
  53                  * a ref
  54                  */
  55                 fd = open(path, O_RDONLY);
  56                 if (fd < 0)
  57                         return NULL;
  58                 len = read(fd, buffer, sizeof(buffer)-1);
  59                 close(fd);
  60
  61                 /*
  62                  * Is it a symbolic ref?
  63                  */
  64                 if (len < 4 || memcmp("ref:", buffer, 4))
  65                         break;
  66                 buf = buffer + 4;
  67                 len -= 4;
  68                 while (len && isspace(*buf))
  69                         buf++, len--;
  70                 while (len && isspace(buf[len-1]))
  71                         buf[--len] = 0;
  72                 path = git_path("%.*s", len, buf);
  73         }
  74         if (len < 40 || get_sha1_hex(buffer, sha1))
  75                 return NULL;
  76         return path;
  77 }
  78
  79 int create_symref(const char *git_HEAD, const char *refs_heads_master)
  80 {
  81         const char *lockpath;
  82         char ref[1000];
  83         int fd, len, written;
  84
  85 #ifndef NO_SYMLINK_HEAD
  86         if (prefer_symlink_refs) {
  87                 unlink(git_HEAD);
  88                 if (!symlink(refs_heads_master, git_HEAD))
  89                         return 0;
  90                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
  91         }
  92 #endif
  93
  94         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
  95         if (sizeof(ref) <= len) {
  96                 error("refname too long: %s", refs_heads_master);
  97                 return -1;
  98         }
  99         lockpath = mkpath("%s.lock", git_HEAD);
 100         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 101         written = write(fd, ref, len);
 102         close(fd);
 103         if (written != len) {
 104                 unlink(lockpath);
 105                 error("Unable to write to %s", lockpath);
 106                 return -2;
 107         }
 108         if (rename(lockpath, git_HEAD) < 0) {
 109                 unlink(lockpath);
 110                 error("Unable to create %s", git_HEAD);
 111                 return -3;
 112         }
 113         if (adjust_shared_perm(git_HEAD)) {
 114                 unlink(lockpath);
 115                 error("Unable to fix permissions on %s", lockpath);
 116                 return -4;
 117         }
 118         return 0;
 119 }
 120
 121 int read_ref(const char *filename, unsigned char *sha1)
 122 {
 123         if (resolve_ref(filename, sha1, 1))
 124                 return 0;
 125         return -1;
 126 }
 127
 128 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 129 {
 130         int retval = 0;
 131         DIR *dir = opendir(git_path("%s", base));
 132
 133         if (dir) {
 134                 struct dirent *de;
 135                 int baselen = strlen(base);
 136                 char *path = xmalloc(baselen + 257);
 137
 138                 if (!strncmp(base, "./", 2)) {
 139                         base += 2;
 140                         baselen -= 2;
 141                 }
 142                 memcpy(path, base, baselen);
 143                 if (baselen && base[baselen-1] != '/')
 144                         path[baselen++] = '/';
 145
 146                 while ((de = readdir(dir)) != NULL) {
 147                         unsigned char sha1[20];
 148                         struct stat st;
 149                         int namelen;
 150
 151                         if (de->d_name[0] == '.')
 152                                 continue;
 153                         namelen = strlen(de->d_name);
 154                         if (namelen > 255)
 155                                 continue;
 156                         if (has_extension(de->d_name, ".lock"))
 157                                 continue;
 158                         memcpy(path + baselen, de->d_name, namelen+1);
 159                         if (stat(git_path("%s", path), &st) < 0)
 160                                 continue;
 161                         if (S_ISDIR(st.st_mode)) {
 162                                 retval = do_for_each_ref(path, fn, trim);
 163                                 if (retval)
 164                                         break;
 165                                 continue;
 166                         }
 167                         if (read_ref(git_path("%s", path), sha1) < 0) {
 168                                 error("%s points nowhere!", path);
 169                                 continue;
 170                         }
 171                         if (!has_sha1_file(sha1)) {
 172                                 error("%s does not point to a valid "
 173                                       "commit object!", path);
 174                                 continue;
 175                         }
 176                         retval = fn(path + trim, sha1);
 177                         if (retval)
 178                                 break;
 179                 }
 180                 free(path);
 181                 closedir(dir);
 182         }
 183         return retval;
 184 }
 185
 186 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 187 {
 188         unsigned char sha1[20];
 189         if (!read_ref(git_path("HEAD"), sha1))
 190                 return fn("HEAD", sha1);
 191         return 0;
 192 }
 193
 194 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 195 {
 196         return do_for_each_ref("refs", fn, 0);
 197 }
 198
 199 int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 200 {
 201         return do_for_each_ref("refs/tags", fn, 10);
 202 }
 203
 204 int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 205 {
 206         return do_for_each_ref("refs/heads", fn, 11);
 207 }
 208
 209 int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 210 {
 211         return do_for_each_ref("refs/remotes", fn, 13);
 212 }
 213
 214 int get_ref_sha1(const char *ref, unsigned char *sha1)
 215 {
 216         if (check_ref_format(ref))
 217                 return -1;
 218         return read_ref(git_path("refs/%s", ref), sha1);
 219 }
 220
 221 /*
 222  * Make sure "ref" is something reasonable to have under ".git/refs/";
 223  * We do not like it if:
 224  *
 225  * - any path component of it begins with ".", or
 226  * - it has double dots "..", or
 227  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 228  * - it ends with a "/".
 229  */
 230
 231 static inline int bad_ref_char(int ch)
 232 {
 233         return (((unsigned) ch) <= ' ' ||
 234                 ch == '~' || ch == '^' || ch == ':' ||
 235                 /* 2.13 Pattern Matching Notation */
 236                 ch == '?' || ch == '*' || ch == '[');
 237 }
 238
 239 int check_ref_format(const char *ref)
 240 {
 241         int ch, level;
 242         const char *cp = ref;
 243
 244         level = 0;
 245         while (1) {
 246                 while ((ch = *cp++) == '/')
 247                         ; /* tolerate duplicated slashes */
 248                 if (!ch)
 249                         return -1; /* should not end with slashes */
 250
 251                 /* we are at the beginning of the path component */
 252                 if (ch == '.' || bad_ref_char(ch))
 253                         return -1;
 254
 255                 /* scan the rest of the path component */
 256                 while ((ch = *cp++) != 0) {
 257                         if (bad_ref_char(ch))
 258                                 return -1;
 259                         if (ch == '/')
 260                                 break;
 261                         if (ch == '.' && *cp == '.')
 262                                 return -1;
 263                 }
 264                 level++;
 265                 if (!ch) {
 266                         if (level < 2)
 267                                 return -1; /* at least of form "heads/blah" */
 268                         return 0;
 269                 }
 270         }
 271 }
 272
 273 static struct ref_lock *verify_lock(struct ref_lock *lock,
 274         const unsigned char *old_sha1, int mustexist)
 275 {
 276         char buf[40];
 277         int nr, fd = open(lock->ref_file, O_RDONLY);
 278         if (fd < 0 && (mustexist || errno != ENOENT)) {
 279                 error("Can't verify ref %s", lock->ref_file);
 280                 unlock_ref(lock);
 281                 return NULL;
 282         }
 283         nr = read(fd, buf, 40);
 284         close(fd);
 285         if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 286                 error("Can't verify ref %s", lock->ref_file);
 287                 unlock_ref(lock);
 288                 return NULL;
 289         }
 290         if (hashcmp(lock->old_sha1, old_sha1)) {
 291                 error("Ref %s is at %s but expected %s", lock->ref_file,
 292                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 293                 unlock_ref(lock);
 294                 return NULL;
 295         }
 296         return lock;
 297 }
 298
 299 static struct ref_lock *lock_ref_sha1_basic(const char *path,
 300         int plen,
 301         const unsigned char *old_sha1, int mustexist)
 302 {
 303         const char *orig_path = path;
 304         struct ref_lock *lock;
 305         struct stat st;
 306
 307         lock = xcalloc(1, sizeof(struct ref_lock));
 308         lock->lock_fd = -1;
 309
 310         plen = strlen(path) - plen;
 311         path = resolve_ref(path, lock->old_sha1, mustexist);
 312         if (!path) {
 313                 int last_errno = errno;
 314                 error("unable to resolve reference %s: %s",
 315                         orig_path, strerror(errno));
 316                 unlock_ref(lock);
 317                 errno = last_errno;
 318                 return NULL;
 319         }
 320         lock->lk = xcalloc(1, sizeof(struct lock_file));
 321
 322         lock->ref_file = xstrdup(path);
 323         lock->log_file = xstrdup(git_path("logs/%s", lock->ref_file + plen));
 324         lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 325
 326         if (safe_create_leading_directories(lock->ref_file))
 327                 die("unable to create directory for %s", lock->ref_file);
 328         lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 329
 330         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 331 }
 332
 333 struct ref_lock *lock_ref_sha1(const char *ref,
 334         const unsigned char *old_sha1, int mustexist)
 335 {
 336         if (check_ref_format(ref))
 337                 return NULL;
 338         return lock_ref_sha1_basic(git_path("refs/%s", ref),
 339                 5 + strlen(ref), old_sha1, mustexist);
 340 }
 341
 342 struct ref_lock *lock_any_ref_for_update(const char *ref,
 343         const unsigned char *old_sha1, int mustexist)
 344 {
 345         return lock_ref_sha1_basic(git_path("%s", ref),
 346                 strlen(ref), old_sha1, mustexist);
 347 }
 348
 349 void unlock_ref(struct ref_lock *lock)
 350 {
 351         if (lock->lock_fd >= 0) {
 352                 close(lock->lock_fd);
 353                 /* Do not free lock->lk -- atexit() still looks at them */
 354                 if (lock->lk)
 355                         rollback_lock_file(lock->lk);
 356         }
 357         free(lock->ref_file);
 358         free(lock->log_file);
 359         free(lock);
 360 }
 361
 362 static int log_ref_write(struct ref_lock *lock,
 363         const unsigned char *sha1, const char *msg)
 364 {
 365         int logfd, written, oflags = O_APPEND | O_WRONLY;
 366         unsigned maxlen, len;
 367         char *logrec;
 368         const char *committer;
 369
 370         if (log_all_ref_updates) {
 371                 if (safe_create_leading_directories(lock->log_file) < 0)
 372                         return error("unable to create directory for %s",
 373                                 lock->log_file);
 374                 oflags |= O_CREAT;
 375         }
 376
 377         logfd = open(lock->log_file, oflags, 0666);
 378         if (logfd < 0) {
 379                 if (!log_all_ref_updates && errno == ENOENT)
 380                         return 0;
 381                 return error("Unable to append to %s: %s",
 382                         lock->log_file, strerror(errno));
 383         }
 384
 385         committer = git_committer_info(1);
 386         if (msg) {
 387                 maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 388                 logrec = xmalloc(maxlen);
 389                 len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 390                         sha1_to_hex(lock->old_sha1),
 391                         sha1_to_hex(sha1),
 392                         committer,
 393                         msg);
 394         }
 395         else {
 396                 maxlen = strlen(committer) + 2*40 + 4;
 397                 logrec = xmalloc(maxlen);
 398                 len = snprintf(logrec, maxlen, "%s %s %s\n",
 399                         sha1_to_hex(lock->old_sha1),
 400                         sha1_to_hex(sha1),
 401                         committer);
 402         }
 403         written = len <= maxlen ? write(logfd, logrec, len) : -1;
 404         free(logrec);
 405         close(logfd);
 406         if (written != len)
 407                 return error("Unable to append to %s", lock->log_file);
 408         return 0;
 409 }
 410
 411 int write_ref_sha1(struct ref_lock *lock,
 412         const unsigned char *sha1, const char *logmsg)
 413 {
 414         static char term = '\n';
 415
 416         if (!lock)
 417                 return -1;
 418         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 419                 unlock_ref(lock);
 420                 return 0;
 421         }
 422         if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 423             write(lock->lock_fd, &term, 1) != 1
 424                 || close(lock->lock_fd) < 0) {
 425                 error("Couldn't write %s", lock->lk->filename);
 426                 unlock_ref(lock);
 427                 return -1;
 428         }
 429         if (log_ref_write(lock, sha1, logmsg) < 0) {
 430                 unlock_ref(lock);
 431                 return -1;
 432         }
 433         if (commit_lock_file(lock->lk)) {
 434                 error("Couldn't set %s", lock->ref_file);
 435                 unlock_ref(lock);
 436                 return -1;
 437         }
 438         lock->lock_fd = -1;
 439         unlock_ref(lock);
 440         return 0;
 441 }
 442
 443 int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 444 {
 445         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 446         char *tz_c;
 447         int logfd, tz;
 448         struct stat st;
 449         unsigned long date;
 450         unsigned char logged_sha1[20];
 451
 452         logfile = git_path("logs/%s", ref);
 453         logfd = open(logfile, O_RDONLY, 0);
 454         if (logfd < 0)
 455                 die("Unable to read log %s: %s", logfile, strerror(errno));
 456         fstat(logfd, &st);
 457         if (!st.st_size)
 458                 die("Log %s is empty.", logfile);
 459         logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 460         close(logfd);
 461
 462         lastrec = NULL;
 463         rec = logend = logdata + st.st_size;
 464         while (logdata < rec) {
 465                 if (logdata < rec && *(rec-1) == '\n')
 466                         rec--;
 467                 lastgt = NULL;
 468                 while (logdata < rec && *(rec-1) != '\n') {
 469                         rec--;
 470                         if (*rec == '>')
 471                                 lastgt = rec;
 472                 }
 473                 if (!lastgt)
 474                         die("Log %s is corrupt.", logfile);
 475                 date = strtoul(lastgt + 1, &tz_c, 10);
 476                 if (date <= at_time) {
 477                         if (lastrec) {
 478                                 if (get_sha1_hex(lastrec, logged_sha1))
 479                                         die("Log %s is corrupt.", logfile);
 480                                 if (get_sha1_hex(rec + 41, sha1))
 481                                         die("Log %s is corrupt.", logfile);
 482                                 if (hashcmp(logged_sha1, sha1)) {
 483                                         tz = strtoul(tz_c, NULL, 10);
 484                                         fprintf(stderr,
 485                                                 "warning: Log %s has gap after %s.\n",
 486                                                 logfile, show_rfc2822_date(date, tz));
 487                                 }
 488                         }
 489                         else if (date == at_time) {
 490                                 if (get_sha1_hex(rec + 41, sha1))
 491                                         die("Log %s is corrupt.", logfile);
 492                         }
 493                         else {
 494                                 if (get_sha1_hex(rec + 41, logged_sha1))
 495                                         die("Log %s is corrupt.", logfile);
 496                                 if (hashcmp(logged_sha1, sha1)) {
 497                                         tz = strtoul(tz_c, NULL, 10);
 498                                         fprintf(stderr,
 499                                                 "warning: Log %s unexpectedly ended on %s.\n",
 500                                                 logfile, show_rfc2822_date(date, tz));
 501                                 }
 502                         }
 503                         munmap((void*)logdata, st.st_size);
 504                         return 0;
 505                 }
 506                 lastrec = rec;
 507         }
 508
 509         rec = logdata;
 510         while (rec < logend && *rec != '>' && *rec != '\n')
 511                 rec++;
 512         if (rec == logend || *rec == '\n')
 513                 die("Log %s is corrupt.", logfile);
 514         date = strtoul(rec + 1, &tz_c, 10);
 515         tz = strtoul(tz_c, NULL, 10);
 516         if (get_sha1_hex(logdata, sha1))
 517                 die("Log %s is corrupt.", logfile);
 518         munmap((void*)logdata, st.st_size);
 519         fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 520                 logfile, show_rfc2822_date(date, tz));
 521         return 0;
 522 }