Andrew's git / gitweb.git / refs.c
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refs.con commit Add support for negative refs (b37a562)
   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                if (is_null_sha1(entry->sha1))
 284                        continue;
 285                if (!has_sha1_file(entry->sha1)) {
 286                        error("%s does not point to a valid object!", entry->name);
 287                        continue;
 288                }
 289                retval = fn(entry->name + trim, entry->sha1);
 290                if (retval)
 291                        return retval;
 292        }
 293
 294        packed = packed ? packed : loose;
 295        while (packed) {
 296                if (!strncmp(base, packed->name, trim)) {
 297                        retval = fn(packed->name + trim, packed->sha1);
 298                        if (retval)
 299                                return retval;
 300                }
 301                packed = packed->next;
 302        }
 303        return 0;
 304}
 305
 306int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 307{
 308        unsigned char sha1[20];
 309        if (!read_ref(git_path("HEAD"), sha1))
 310                return fn("HEAD", sha1);
 311        return 0;
 312}
 313
 314int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 315{
 316        return do_for_each_ref("refs/", fn, 0);
 317}
 318
 319int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 320{
 321        return do_for_each_ref("refs/tags/", fn, 10);
 322}
 323
 324int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 325{
 326        return do_for_each_ref("refs/heads/", fn, 11);
 327}
 328
 329int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 330{
 331        return do_for_each_ref("refs/remotes/", fn, 13);
 332}
 333
 334int get_ref_sha1(const char *ref, unsigned char *sha1)
 335{
 336        if (check_ref_format(ref))
 337                return -1;
 338        return read_ref(git_path("refs/%s", ref), sha1);
 339}
 340
 341/*
 342 * Make sure "ref" is something reasonable to have under ".git/refs/";
 343 * We do not like it if:
 344 *
 345 * - any path component of it begins with ".", or
 346 * - it has double dots "..", or
 347 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 348 * - it ends with a "/".
 349 */
 350
 351static inline int bad_ref_char(int ch)
 352{
 353        return (((unsigned) ch) <= ' ' ||
 354                ch == '~' || ch == '^' || ch == ':' ||
 355                /* 2.13 Pattern Matching Notation */
 356                ch == '?' || ch == '*' || ch == '[');
 357}
 358
 359int check_ref_format(const char *ref)
 360{
 361        int ch, level;
 362        const char *cp = ref;
 363
 364        level = 0;
 365        while (1) {
 366                while ((ch = *cp++) == '/')
 367                        ; /* tolerate duplicated slashes */
 368                if (!ch)
 369                        return -1; /* should not end with slashes */
 370
 371                /* we are at the beginning of the path component */
 372                if (ch == '.' || bad_ref_char(ch))
 373                        return -1;
 374
 375                /* scan the rest of the path component */
 376                while ((ch = *cp++) != 0) {
 377                        if (bad_ref_char(ch))
 378                                return -1;
 379                        if (ch == '/')
 380                                break;
 381                        if (ch == '.' && *cp == '.')
 382                                return -1;
 383                }
 384                level++;
 385                if (!ch) {
 386                        if (level < 2)
 387                                return -1; /* at least of form "heads/blah" */
 388                        return 0;
 389                }
 390        }
 391}
 392
 393static struct ref_lock *verify_lock(struct ref_lock *lock,
 394        const unsigned char *old_sha1, int mustexist)
 395{
 396        char buf[40];
 397        int nr, fd = open(lock->ref_file, O_RDONLY);
 398        if (fd < 0 && (mustexist || errno != ENOENT)) {
 399                error("Can't verify ref %s", lock->ref_file);
 400                unlock_ref(lock);
 401                return NULL;
 402        }
 403        nr = read(fd, buf, 40);
 404        close(fd);
 405        if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 406                error("Can't verify ref %s", lock->ref_file);
 407                unlock_ref(lock);
 408                return NULL;
 409        }
 410        if (hashcmp(lock->old_sha1, old_sha1)) {
 411                error("Ref %s is at %s but expected %s", lock->ref_file,
 412                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 413                unlock_ref(lock);
 414                return NULL;
 415        }
 416        return lock;
 417}
 418
 419static struct ref_lock *lock_ref_sha1_basic(const char *path,
 420        int plen,
 421        const unsigned char *old_sha1, int mustexist)
 422{
 423        const char *orig_path = path;
 424        struct ref_lock *lock;
 425        struct stat st;
 426
 427        lock = xcalloc(1, sizeof(struct ref_lock));
 428        lock->lock_fd = -1;
 429
 430        plen = strlen(path) - plen;
 431        path = resolve_ref(path, lock->old_sha1, mustexist);
 432        if (!path) {
 433                int last_errno = errno;
 434                error("unable to resolve reference %s: %s",
 435                        orig_path, strerror(errno));
 436                unlock_ref(lock);
 437                errno = last_errno;
 438                return NULL;
 439        }
 440        lock->lk = xcalloc(1, sizeof(struct lock_file));
 441
 442        lock->ref_file = xstrdup(path);
 443        lock->log_file = xstrdup(git_path("logs/%s", lock->ref_file + plen));
 444        lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 445
 446        if (safe_create_leading_directories(lock->ref_file))
 447                die("unable to create directory for %s", lock->ref_file);
 448        lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 449
 450        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 451}
 452
 453struct ref_lock *lock_ref_sha1(const char *ref,
 454        const unsigned char *old_sha1, int mustexist)
 455{
 456        if (check_ref_format(ref))
 457                return NULL;
 458        return lock_ref_sha1_basic(git_path("refs/%s", ref),
 459                5 + strlen(ref), old_sha1, mustexist);
 460}
 461
 462struct ref_lock *lock_any_ref_for_update(const char *ref,
 463        const unsigned char *old_sha1, int mustexist)
 464{
 465        return lock_ref_sha1_basic(git_path("%s", ref),
 466                strlen(ref), old_sha1, mustexist);
 467}
 468
 469void unlock_ref(struct ref_lock *lock)
 470{
 471        if (lock->lock_fd >= 0) {
 472                close(lock->lock_fd);
 473                /* Do not free lock->lk -- atexit() still looks at them */
 474                if (lock->lk)
 475                        rollback_lock_file(lock->lk);
 476        }
 477        free(lock->ref_file);
 478        free(lock->log_file);
 479        free(lock);
 480}
 481
 482static int log_ref_write(struct ref_lock *lock,
 483        const unsigned char *sha1, const char *msg)
 484{
 485        int logfd, written, oflags = O_APPEND | O_WRONLY;
 486        unsigned maxlen, len;
 487        char *logrec;
 488        const char *committer;
 489
 490        if (log_all_ref_updates) {
 491                if (safe_create_leading_directories(lock->log_file) < 0)
 492                        return error("unable to create directory for %s",
 493                                lock->log_file);
 494                oflags |= O_CREAT;
 495        }
 496
 497        logfd = open(lock->log_file, oflags, 0666);
 498        if (logfd < 0) {
 499                if (!log_all_ref_updates && errno == ENOENT)
 500                        return 0;
 501                return error("Unable to append to %s: %s",
 502                        lock->log_file, strerror(errno));
 503        }
 504
 505        committer = git_committer_info(1);
 506        if (msg) {
 507                maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 508                logrec = xmalloc(maxlen);
 509                len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 510                        sha1_to_hex(lock->old_sha1),
 511                        sha1_to_hex(sha1),
 512                        committer,
 513                        msg);
 514        }
 515        else {
 516                maxlen = strlen(committer) + 2*40 + 4;
 517                logrec = xmalloc(maxlen);
 518                len = snprintf(logrec, maxlen, "%s %s %s\n",
 519                        sha1_to_hex(lock->old_sha1),
 520                        sha1_to_hex(sha1),
 521                        committer);
 522        }
 523        written = len <= maxlen ? write(logfd, logrec, len) : -1;
 524        free(logrec);
 525        close(logfd);
 526        if (written != len)
 527                return error("Unable to append to %s", lock->log_file);
 528        return 0;
 529}
 530
 531int write_ref_sha1(struct ref_lock *lock,
 532        const unsigned char *sha1, const char *logmsg)
 533{
 534        static char term = '\n';
 535
 536        if (!lock)
 537                return -1;
 538        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 539                unlock_ref(lock);
 540                return 0;
 541        }
 542        if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 543            write(lock->lock_fd, &term, 1) != 1
 544                || close(lock->lock_fd) < 0) {
 545                error("Couldn't write %s", lock->lk->filename);
 546                unlock_ref(lock);
 547                return -1;
 548        }
 549        if (log_ref_write(lock, sha1, logmsg) < 0) {
 550                unlock_ref(lock);
 551                return -1;
 552        }
 553        if (commit_lock_file(lock->lk)) {
 554                error("Couldn't set %s", lock->ref_file);
 555                unlock_ref(lock);
 556                return -1;
 557        }
 558        lock->lock_fd = -1;
 559        unlock_ref(lock);
 560        return 0;
 561}
 562
 563int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 564{
 565        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 566        char *tz_c;
 567        int logfd, tz;
 568        struct stat st;
 569        unsigned long date;
 570        unsigned char logged_sha1[20];
 571
 572        logfile = git_path("logs/%s", ref);
 573        logfd = open(logfile, O_RDONLY, 0);
 574        if (logfd < 0)
 575                die("Unable to read log %s: %s", logfile, strerror(errno));
 576        fstat(logfd, &st);
 577        if (!st.st_size)
 578                die("Log %s is empty.", logfile);
 579        logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 580        close(logfd);
 581
 582        lastrec = NULL;
 583        rec = logend = logdata + st.st_size;
 584        while (logdata < rec) {
 585                if (logdata < rec && *(rec-1) == '\n')
 586                        rec--;
 587                lastgt = NULL;
 588                while (logdata < rec && *(rec-1) != '\n') {
 589                        rec--;
 590                        if (*rec == '>')
 591                                lastgt = rec;
 592                }
 593                if (!lastgt)
 594                        die("Log %s is corrupt.", logfile);
 595                date = strtoul(lastgt + 1, &tz_c, 10);
 596                if (date <= at_time) {
 597                        if (lastrec) {
 598                                if (get_sha1_hex(lastrec, logged_sha1))
 599                                        die("Log %s is corrupt.", logfile);
 600                                if (get_sha1_hex(rec + 41, sha1))
 601                                        die("Log %s is corrupt.", logfile);
 602                                if (hashcmp(logged_sha1, sha1)) {
 603                                        tz = strtoul(tz_c, NULL, 10);
 604                                        fprintf(stderr,
 605                                                "warning: Log %s has gap after %s.\n",
 606                                                logfile, show_rfc2822_date(date, tz));
 607                                }
 608                        }
 609                        else if (date == at_time) {
 610                                if (get_sha1_hex(rec + 41, sha1))
 611                                        die("Log %s is corrupt.", logfile);
 612                        }
 613                        else {
 614                                if (get_sha1_hex(rec + 41, logged_sha1))
 615                                        die("Log %s is corrupt.", logfile);
 616                                if (hashcmp(logged_sha1, sha1)) {
 617                                        tz = strtoul(tz_c, NULL, 10);
 618                                        fprintf(stderr,
 619                                                "warning: Log %s unexpectedly ended on %s.\n",
 620                                                logfile, show_rfc2822_date(date, tz));
 621                                }
 622                        }
 623                        munmap((void*)logdata, st.st_size);
 624                        return 0;
 625                }
 626                lastrec = rec;
 627        }
 628
 629        rec = logdata;
 630        while (rec < logend && *rec != '>' && *rec != '\n')
 631                rec++;
 632        if (rec == logend || *rec == '\n')
 633                die("Log %s is corrupt.", logfile);
 634        date = strtoul(rec + 1, &tz_c, 10);
 635        tz = strtoul(tz_c, NULL, 10);
 636        if (get_sha1_hex(logdata, sha1))
 637                die("Log %s is corrupt.", logfile);
 638        munmap((void*)logdata, st.st_size);
 639        fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 640                logfile, show_rfc2822_date(date, tz));
 641        return 0;
 642}