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