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