Andrew's git / gitweb.git / refs.c
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refs.con commit Start handling references internally as a sorted in-memory list (e1e22e3)
   1#include "refs.h"
   2#include "cache.h"
   3
   4#include <errno.h>
   5
   6struct ref_list {
   7        struct ref_list *next;
   8        unsigned char sha1[20];
   9        char name[FLEX_ARRAY];
  10};
  11
  12static const char *parse_ref_line(char *line, unsigned char *sha1)
  13{
  14        /*
  15         * 42: the answer to everything.
  16         *
  17         * In this case, it happens to be the answer to
  18         *  40 (length of sha1 hex representation)
  19         *  +1 (space in between hex and name)
  20         *  +1 (newline at the end of the line)
  21         */
  22        int len = strlen(line) - 42;
  23
  24        if (len <= 0)
  25                return NULL;
  26        if (get_sha1_hex(line, sha1) < 0)
  27                return NULL;
  28        if (!isspace(line[40]))
  29                return NULL;
  30        line += 41;
  31        if (line[len] != '\n')
  32                return NULL;
  33        line[len] = 0;
  34        return line;
  35}
  36
  37static struct ref_list *add_ref(const char *name, const unsigned char *sha1, struct ref_list *list)
  38{
  39        int len;
  40        struct ref_list **p = &list, *entry;
  41
  42        /* Find the place to insert the ref into.. */
  43        while ((entry = *p) != NULL) {
  44                int cmp = strcmp(entry->name, name);
  45                if (cmp > 0)
  46                        break;
  47
  48                /* Same as existing entry? */
  49                if (!cmp)
  50                        return list;
  51                p = &entry->next;
  52        }
  53
  54        /* Allocate it and add it in.. */
  55        len = strlen(name) + 1;
  56        entry = xmalloc(sizeof(struct ref_list) + len);
  57        hashcpy(entry->sha1, sha1);
  58        memcpy(entry->name, name, len);
  59        entry->next = *p;
  60        *p = entry;
  61        return list;
  62}
  63
  64static struct ref_list *get_packed_refs(void)
  65{
  66        static int did_refs = 0;
  67        static struct ref_list *refs = NULL;
  68
  69        if (!did_refs) {
  70                FILE *f = fopen(git_path("packed-refs"), "r");
  71                if (f) {
  72                        struct ref_list *list = NULL;
  73                        char refline[PATH_MAX];
  74                        while (fgets(refline, sizeof(refline), f)) {
  75                                unsigned char sha1[20];
  76                                const char *name = parse_ref_line(refline, sha1);
  77                                if (!name)
  78                                        continue;
  79                                list = add_ref(name, sha1, list);
  80                        }
  81                        fclose(f);
  82                        refs = list;
  83                }
  84                did_refs = 1;
  85        }
  86        return refs;
  87}
  88
  89static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
  90{
  91        DIR *dir = opendir(git_path("%s", base));
  92
  93        if (dir) {
  94                struct dirent *de;
  95                int baselen = strlen(base);
  96                char *path = xmalloc(baselen + 257);
  97
  98                memcpy(path, base, baselen);
  99                if (baselen && base[baselen-1] != '/')
 100                        path[baselen++] = '/';
 101
 102                while ((de = readdir(dir)) != NULL) {
 103                        unsigned char sha1[20];
 104                        struct stat st;
 105                        int namelen;
 106
 107                        if (de->d_name[0] == '.')
 108                                continue;
 109                        namelen = strlen(de->d_name);
 110                        if (namelen > 255)
 111                                continue;
 112                        if (has_extension(de->d_name, ".lock"))
 113                                continue;
 114                        memcpy(path + baselen, de->d_name, namelen+1);
 115                        if (stat(git_path("%s", path), &st) < 0)
 116                                continue;
 117                        if (S_ISDIR(st.st_mode)) {
 118                                list = get_ref_dir(path, list);
 119                                continue;
 120                        }
 121                        if (read_ref(git_path("%s", path), sha1) < 0) {
 122                                error("%s points nowhere!", path);
 123                                continue;
 124                        }
 125                        list = add_ref(path, sha1, list);
 126                }
 127                free(path);
 128                closedir(dir);
 129        }
 130        return list;
 131}
 132
 133static struct ref_list *get_loose_refs(void)
 134{
 135        static int did_refs = 0;
 136        static struct ref_list *refs = NULL;
 137
 138        if (!did_refs) {
 139                refs = get_ref_dir("refs", NULL);
 140                did_refs = 1;
 141        }
 142        return refs;
 143}
 144
 145/* We allow "recursive" symbolic refs. Only within reason, though */
 146#define MAXDEPTH 5
 147
 148const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
 149{
 150        int depth = MAXDEPTH, len;
 151        char buffer[256];
 152
 153        for (;;) {
 154                struct stat st;
 155                char *buf;
 156                int fd;
 157
 158                if (--depth < 0)
 159                        return NULL;
 160
 161                /* Special case: non-existing file.
 162                 * Not having the refs/heads/new-branch is OK
 163                 * if we are writing into it, so is .git/HEAD
 164                 * that points at refs/heads/master still to be
 165                 * born.  It is NOT OK if we are resolving for
 166                 * reading.
 167                 */
 168                if (lstat(path, &st) < 0) {
 169                        if (reading || errno != ENOENT)
 170                                return NULL;
 171                        hashclr(sha1);
 172                        return path;
 173                }
 174
 175                /* Follow "normalized" - ie "refs/.." symlinks by hand */
 176                if (S_ISLNK(st.st_mode)) {
 177                        len = readlink(path, buffer, sizeof(buffer)-1);
 178                        if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 179                                path = git_path("%.*s", len, buffer);
 180                                continue;
 181                        }
 182                }
 183
 184                /*
 185                 * Anything else, just open it and try to use it as
 186                 * a ref
 187                 */
 188                fd = open(path, O_RDONLY);
 189                if (fd < 0)
 190                        return NULL;
 191                len = read(fd, buffer, sizeof(buffer)-1);
 192                close(fd);
 193
 194                /*
 195                 * Is it a symbolic ref?
 196                 */
 197                if (len < 4 || memcmp("ref:", buffer, 4))
 198                        break;
 199                buf = buffer + 4;
 200                len -= 4;
 201                while (len && isspace(*buf))
 202                        buf++, len--;
 203                while (len && isspace(buf[len-1]))
 204                        buf[--len] = 0;
 205                path = git_path("%.*s", len, buf);
 206        }
 207        if (len < 40 || get_sha1_hex(buffer, sha1))
 208                return NULL;
 209        return path;
 210}
 211
 212int create_symref(const char *git_HEAD, const char *refs_heads_master)
 213{
 214        const char *lockpath;
 215        char ref[1000];
 216        int fd, len, written;
 217
 218#ifndef NO_SYMLINK_HEAD
 219        if (prefer_symlink_refs) {
 220                unlink(git_HEAD);
 221                if (!symlink(refs_heads_master, git_HEAD))
 222                        return 0;
 223                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 224        }
 225#endif
 226
 227        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 228        if (sizeof(ref) <= len) {
 229                error("refname too long: %s", refs_heads_master);
 230                return -1;
 231        }
 232        lockpath = mkpath("%s.lock", git_HEAD);
 233        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
 234        written = write(fd, ref, len);
 235        close(fd);
 236        if (written != len) {
 237                unlink(lockpath);
 238                error("Unable to write to %s", lockpath);
 239                return -2;
 240        }
 241        if (rename(lockpath, git_HEAD) < 0) {
 242                unlink(lockpath);
 243                error("Unable to create %s", git_HEAD);
 244                return -3;
 245        }
 246        if (adjust_shared_perm(git_HEAD)) {
 247                unlink(lockpath);
 248                error("Unable to fix permissions on %s", lockpath);
 249                return -4;
 250        }
 251        return 0;
 252}
 253
 254int read_ref(const char *filename, unsigned char *sha1)
 255{
 256        if (resolve_ref(filename, sha1, 1))
 257                return 0;
 258        return -1;
 259}
 260
 261static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 262{
 263        int retval;
 264        struct ref_list *packed = get_packed_refs();
 265        struct ref_list *loose = get_loose_refs();
 266
 267        while (packed && loose) {
 268                struct ref_list *entry;
 269                int cmp = strcmp(packed->name, loose->name);
 270                if (!cmp) {
 271                        packed = packed->next;
 272                        continue;
 273                }
 274                if (cmp > 0) {
 275                        entry = loose;
 276                        loose = loose->next;
 277                } else {
 278                        entry = packed;
 279                        packed = packed->next;
 280                }
 281                if (strncmp(base, entry->name, trim))
 282                        continue;
 283                retval = fn(entry->name + trim, entry->sha1);
 284                if (retval)
 285                        return retval;
 286        }
 287
 288        packed = packed ? packed : loose;
 289        while (packed) {
 290                if (!strncmp(base, packed->name, trim)) {
 291                        retval = fn(packed->name + trim, packed->sha1);
 292                        if (retval)
 293                                return retval;
 294                }
 295                packed = packed->next;
 296        }
 297        return 0;
 298}
 299
 300int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 301{
 302        unsigned char sha1[20];
 303        if (!read_ref(git_path("HEAD"), sha1))
 304                return fn("HEAD", sha1);
 305        return 0;
 306}
 307
 308int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 309{
 310        return do_for_each_ref("refs/", fn, 0);
 311}
 312
 313int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 314{
 315        return do_for_each_ref("refs/tags/", fn, 10);
 316}
 317
 318int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 319{
 320        return do_for_each_ref("refs/heads/", fn, 11);
 321}
 322
 323int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 324{
 325        return do_for_each_ref("refs/remotes/", fn, 13);
 326}
 327
 328int get_ref_sha1(const char *ref, unsigned char *sha1)
 329{
 330        if (check_ref_format(ref))
 331                return -1;
 332        return read_ref(git_path("refs/%s", ref), sha1);
 333}
 334
 335/*
 336 * Make sure "ref" is something reasonable to have under ".git/refs/";
 337 * We do not like it if:
 338 *
 339 * - any path component of it begins with ".", or
 340 * - it has double dots "..", or
 341 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 342 * - it ends with a "/".
 343 */
 344
 345static inline int bad_ref_char(int ch)
 346{
 347        return (((unsigned) ch) <= ' ' ||
 348                ch == '~' || ch == '^' || ch == ':' ||
 349                /* 2.13 Pattern Matching Notation */
 350                ch == '?' || ch == '*' || ch == '[');
 351}
 352
 353int check_ref_format(const char *ref)
 354{
 355        int ch, level;
 356        const char *cp = ref;
 357
 358        level = 0;
 359        while (1) {
 360                while ((ch = *cp++) == '/')
 361                        ; /* tolerate duplicated slashes */
 362                if (!ch)
 363                        return -1; /* should not end with slashes */
 364
 365                /* we are at the beginning of the path component */
 366                if (ch == '.' || bad_ref_char(ch))
 367                        return -1;
 368
 369                /* scan the rest of the path component */
 370                while ((ch = *cp++) != 0) {
 371                        if (bad_ref_char(ch))
 372                                return -1;
 373                        if (ch == '/')
 374                                break;
 375                        if (ch == '.' && *cp == '.')
 376                                return -1;
 377                }
 378                level++;
 379                if (!ch) {
 380                        if (level < 2)
 381                                return -1; /* at least of form "heads/blah" */
 382                        return 0;
 383                }
 384        }
 385}
 386
 387static struct ref_lock *verify_lock(struct ref_lock *lock,
 388        const unsigned char *old_sha1, int mustexist)
 389{
 390        char buf[40];
 391        int nr, fd = open(lock->ref_file, O_RDONLY);
 392        if (fd < 0 && (mustexist || errno != ENOENT)) {
 393                error("Can't verify ref %s", lock->ref_file);
 394                unlock_ref(lock);
 395                return NULL;
 396        }
 397        nr = read(fd, buf, 40);
 398        close(fd);
 399        if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 400                error("Can't verify ref %s", lock->ref_file);
 401                unlock_ref(lock);
 402                return NULL;
 403        }
 404        if (hashcmp(lock->old_sha1, old_sha1)) {
 405                error("Ref %s is at %s but expected %s", lock->ref_file,
 406                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 407                unlock_ref(lock);
 408                return NULL;
 409        }
 410        return lock;
 411}
 412
 413static struct ref_lock *lock_ref_sha1_basic(const char *path,
 414        int plen,
 415        const unsigned char *old_sha1, int mustexist)
 416{
 417        const char *orig_path = path;
 418        struct ref_lock *lock;
 419        struct stat st;
 420
 421        lock = xcalloc(1, sizeof(struct ref_lock));
 422        lock->lock_fd = -1;
 423
 424        plen = strlen(path) - plen;
 425        path = resolve_ref(path, lock->old_sha1, mustexist);
 426        if (!path) {
 427                int last_errno = errno;
 428                error("unable to resolve reference %s: %s",
 429                        orig_path, strerror(errno));
 430                unlock_ref(lock);
 431                errno = last_errno;
 432                return NULL;
 433        }
 434        lock->lk = xcalloc(1, sizeof(struct lock_file));
 435
 436        lock->ref_file = xstrdup(path);
 437        lock->log_file = xstrdup(git_path("logs/%s", lock->ref_file + plen));
 438        lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 439
 440        if (safe_create_leading_directories(lock->ref_file))
 441                die("unable to create directory for %s", lock->ref_file);
 442        lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 443
 444        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 445}
 446
 447struct ref_lock *lock_ref_sha1(const char *ref,
 448        const unsigned char *old_sha1, int mustexist)
 449{
 450        if (check_ref_format(ref))
 451                return NULL;
 452        return lock_ref_sha1_basic(git_path("refs/%s", ref),
 453                5 + strlen(ref), old_sha1, mustexist);
 454}
 455
 456struct ref_lock *lock_any_ref_for_update(const char *ref,
 457        const unsigned char *old_sha1, int mustexist)
 458{
 459        return lock_ref_sha1_basic(git_path("%s", ref),
 460                strlen(ref), old_sha1, mustexist);
 461}
 462
 463void unlock_ref(struct ref_lock *lock)
 464{
 465        if (lock->lock_fd >= 0) {
 466                close(lock->lock_fd);
 467                /* Do not free lock->lk -- atexit() still looks at them */
 468                if (lock->lk)
 469                        rollback_lock_file(lock->lk);
 470        }
 471        free(lock->ref_file);
 472        free(lock->log_file);
 473        free(lock);
 474}
 475
 476static int log_ref_write(struct ref_lock *lock,
 477        const unsigned char *sha1, const char *msg)
 478{
 479        int logfd, written, oflags = O_APPEND | O_WRONLY;
 480        unsigned maxlen, len;
 481        char *logrec;
 482        const char *committer;
 483
 484        if (log_all_ref_updates) {
 485                if (safe_create_leading_directories(lock->log_file) < 0)
 486                        return error("unable to create directory for %s",
 487                                lock->log_file);
 488                oflags |= O_CREAT;
 489        }
 490
 491        logfd = open(lock->log_file, oflags, 0666);
 492        if (logfd < 0) {
 493                if (!log_all_ref_updates && errno == ENOENT)
 494                        return 0;
 495                return error("Unable to append to %s: %s",
 496                        lock->log_file, strerror(errno));
 497        }
 498
 499        committer = git_committer_info(1);
 500        if (msg) {
 501                maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 502                logrec = xmalloc(maxlen);
 503                len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 504                        sha1_to_hex(lock->old_sha1),
 505                        sha1_to_hex(sha1),
 506                        committer,
 507                        msg);
 508        }
 509        else {
 510                maxlen = strlen(committer) + 2*40 + 4;
 511                logrec = xmalloc(maxlen);
 512                len = snprintf(logrec, maxlen, "%s %s %s\n",
 513                        sha1_to_hex(lock->old_sha1),
 514                        sha1_to_hex(sha1),
 515                        committer);
 516        }
 517        written = len <= maxlen ? write(logfd, logrec, len) : -1;
 518        free(logrec);
 519        close(logfd);
 520        if (written != len)
 521                return error("Unable to append to %s", lock->log_file);
 522        return 0;
 523}
 524
 525int write_ref_sha1(struct ref_lock *lock,
 526        const unsigned char *sha1, const char *logmsg)
 527{
 528        static char term = '\n';
 529
 530        if (!lock)
 531                return -1;
 532        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 533                unlock_ref(lock);
 534                return 0;
 535        }
 536        if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 537            write(lock->lock_fd, &term, 1) != 1
 538                || close(lock->lock_fd) < 0) {
 539                error("Couldn't write %s", lock->lk->filename);
 540                unlock_ref(lock);
 541                return -1;
 542        }
 543        if (log_ref_write(lock, sha1, logmsg) < 0) {
 544                unlock_ref(lock);
 545                return -1;
 546        }
 547        if (commit_lock_file(lock->lk)) {
 548                error("Couldn't set %s", lock->ref_file);
 549                unlock_ref(lock);
 550                return -1;
 551        }
 552        lock->lock_fd = -1;
 553        unlock_ref(lock);
 554        return 0;
 555}
 556
 557int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 558{
 559        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 560        char *tz_c;
 561        int logfd, tz;
 562        struct stat st;
 563        unsigned long date;
 564        unsigned char logged_sha1[20];
 565
 566        logfile = git_path("logs/%s", ref);
 567        logfd = open(logfile, O_RDONLY, 0);
 568        if (logfd < 0)
 569                die("Unable to read log %s: %s", logfile, strerror(errno));
 570        fstat(logfd, &st);
 571        if (!st.st_size)
 572                die("Log %s is empty.", logfile);
 573        logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 574        close(logfd);
 575
 576        lastrec = NULL;
 577        rec = logend = logdata + st.st_size;
 578        while (logdata < rec) {
 579                if (logdata < rec && *(rec-1) == '\n')
 580                        rec--;
 581                lastgt = NULL;
 582                while (logdata < rec && *(rec-1) != '\n') {
 583                        rec--;
 584                        if (*rec == '>')
 585                                lastgt = rec;
 586                }
 587                if (!lastgt)
 588                        die("Log %s is corrupt.", logfile);
 589                date = strtoul(lastgt + 1, &tz_c, 10);
 590                if (date <= at_time) {
 591                        if (lastrec) {
 592                                if (get_sha1_hex(lastrec, logged_sha1))
 593                                        die("Log %s is corrupt.", logfile);
 594                                if (get_sha1_hex(rec + 41, sha1))
 595                                        die("Log %s is corrupt.", logfile);
 596                                if (hashcmp(logged_sha1, sha1)) {
 597                                        tz = strtoul(tz_c, NULL, 10);
 598                                        fprintf(stderr,
 599                                                "warning: Log %s has gap after %s.\n",
 600                                                logfile, show_rfc2822_date(date, tz));
 601                                }
 602                        }
 603                        else if (date == at_time) {
 604                                if (get_sha1_hex(rec + 41, sha1))
 605                                        die("Log %s is corrupt.", logfile);
 606                        }
 607                        else {
 608                                if (get_sha1_hex(rec + 41, logged_sha1))
 609                                        die("Log %s is corrupt.", logfile);
 610                                if (hashcmp(logged_sha1, sha1)) {
 611                                        tz = strtoul(tz_c, NULL, 10);
 612                                        fprintf(stderr,
 613                                                "warning: Log %s unexpectedly ended on %s.\n",
 614                                                logfile, show_rfc2822_date(date, tz));
 615                                }
 616                        }
 617                        munmap((void*)logdata, st.st_size);
 618                        return 0;
 619                }
 620                lastrec = rec;
 621        }
 622
 623        rec = logdata;
 624        while (rec < logend && *rec != '>' && *rec != '\n')
 625                rec++;
 626        if (rec == logend || *rec == '\n')
 627                die("Log %s is corrupt.", logfile);
 628        date = strtoul(rec + 1, &tz_c, 10);
 629        tz = strtoul(tz_c, NULL, 10);
 630        if (get_sha1_hex(logdata, sha1))
 631                die("Log %s is corrupt.", logfile);
 632        munmap((void*)logdata, st.st_size);
 633        fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 634                logfile, show_rfc2822_date(date, tz));
 635        return 0;
 636}