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