Andrew's git / gitweb.git / refs.c
?
refs.con commit lock_ref_sha1(): do not sometimes error() and sometimes die(). (5cc3cef)
   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 flag; /* ISSYMREF? ISPACKED? */
   9        unsigned char sha1[20];
  10        char name[FLEX_ARRAY];
  11};
  12
  13static const char *parse_ref_line(char *line, unsigned char *sha1)
  14{
  15        /*
  16         * 42: the answer to everything.
  17         *
  18         * In this case, it happens to be the answer to
  19         *  40 (length of sha1 hex representation)
  20         *  +1 (space in between hex and name)
  21         *  +1 (newline at the end of the line)
  22         */
  23        int len = strlen(line) - 42;
  24
  25        if (len <= 0)
  26                return NULL;
  27        if (get_sha1_hex(line, sha1) < 0)
  28                return NULL;
  29        if (!isspace(line[40]))
  30                return NULL;
  31        line += 41;
  32        if (isspace(*line))
  33                return NULL;
  34        if (line[len] != '\n')
  35                return NULL;
  36        line[len] = 0;
  37        return line;
  38}
  39
  40static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  41                                int flag, struct ref_list *list)
  42{
  43        int len;
  44        struct ref_list **p = &list, *entry;
  45
  46        /* Find the place to insert the ref into.. */
  47        while ((entry = *p) != NULL) {
  48                int cmp = strcmp(entry->name, name);
  49                if (cmp > 0)
  50                        break;
  51
  52                /* Same as existing entry? */
  53                if (!cmp)
  54                        return list;
  55                p = &entry->next;
  56        }
  57
  58        /* Allocate it and add it in.. */
  59        len = strlen(name) + 1;
  60        entry = xmalloc(sizeof(struct ref_list) + len);
  61        hashcpy(entry->sha1, sha1);
  62        memcpy(entry->name, name, len);
  63        entry->flag = flag;
  64        entry->next = *p;
  65        *p = entry;
  66        return list;
  67}
  68
  69/*
  70 * Future: need to be in "struct repository"
  71 * when doing a full libification.
  72 */
  73struct cached_refs {
  74        char did_loose;
  75        char did_packed;
  76        struct ref_list *loose;
  77        struct ref_list *packed;
  78} cached_refs;
  79
  80static void free_ref_list(struct ref_list *list)
  81{
  82        struct ref_list *next;
  83        for ( ; list; list = next) {
  84                next = list->next;
  85                free(list);
  86        }
  87}
  88
  89static void invalidate_cached_refs(void)
  90{
  91        struct cached_refs *ca = &cached_refs;
  92
  93        if (ca->did_loose && ca->loose)
  94                free_ref_list(ca->loose);
  95        if (ca->did_packed && ca->packed)
  96                free_ref_list(ca->packed);
  97        ca->loose = ca->packed = NULL;
  98        ca->did_loose = ca->did_packed = 0;
  99}
 100
 101static struct ref_list *get_packed_refs(void)
 102{
 103        if (!cached_refs.did_packed) {
 104                struct ref_list *refs = NULL;
 105                FILE *f = fopen(git_path("packed-refs"), "r");
 106                if (f) {
 107                        struct ref_list *list = NULL;
 108                        char refline[PATH_MAX];
 109                        while (fgets(refline, sizeof(refline), f)) {
 110                                unsigned char sha1[20];
 111                                const char *name = parse_ref_line(refline, sha1);
 112                                if (!name)
 113                                        continue;
 114                                list = add_ref(name, sha1, REF_ISPACKED, list);
 115                        }
 116                        fclose(f);
 117                        refs = list;
 118                }
 119                cached_refs.packed = refs;
 120                cached_refs.did_packed = 1;
 121        }
 122        return cached_refs.packed;
 123}
 124
 125static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 126{
 127        DIR *dir = opendir(git_path("%s", base));
 128
 129        if (dir) {
 130                struct dirent *de;
 131                int baselen = strlen(base);
 132                char *ref = xmalloc(baselen + 257);
 133
 134                memcpy(ref, base, baselen);
 135                if (baselen && base[baselen-1] != '/')
 136                        ref[baselen++] = '/';
 137
 138                while ((de = readdir(dir)) != NULL) {
 139                        unsigned char sha1[20];
 140                        struct stat st;
 141                        int flag;
 142                        int namelen;
 143
 144                        if (de->d_name[0] == '.')
 145                                continue;
 146                        namelen = strlen(de->d_name);
 147                        if (namelen > 255)
 148                                continue;
 149                        if (has_extension(de->d_name, ".lock"))
 150                                continue;
 151                        memcpy(ref + baselen, de->d_name, namelen+1);
 152                        if (stat(git_path("%s", ref), &st) < 0)
 153                                continue;
 154                        if (S_ISDIR(st.st_mode)) {
 155                                list = get_ref_dir(ref, list);
 156                                continue;
 157                        }
 158                        if (!resolve_ref(ref, sha1, 1, &flag)) {
 159                                error("%s points nowhere!", ref);
 160                                continue;
 161                        }
 162                        list = add_ref(ref, sha1, flag, list);
 163                }
 164                free(ref);
 165                closedir(dir);
 166        }
 167        return list;
 168}
 169
 170static struct ref_list *get_loose_refs(void)
 171{
 172        if (!cached_refs.did_loose) {
 173                cached_refs.loose = get_ref_dir("refs", NULL);
 174                cached_refs.did_loose = 1;
 175        }
 176        return cached_refs.loose;
 177}
 178
 179/* We allow "recursive" symbolic refs. Only within reason, though */
 180#define MAXDEPTH 5
 181
 182const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 183{
 184        int depth = MAXDEPTH, len;
 185        char buffer[256];
 186        static char ref_buffer[256];
 187
 188        if (flag)
 189                *flag = 0;
 190
 191        for (;;) {
 192                const char *path = git_path("%s", ref);
 193                struct stat st;
 194                char *buf;
 195                int fd;
 196
 197                if (--depth < 0)
 198                        return NULL;
 199
 200                /* Special case: non-existing file.
 201                 * Not having the refs/heads/new-branch is OK
 202                 * if we are writing into it, so is .git/HEAD
 203                 * that points at refs/heads/master still to be
 204                 * born.  It is NOT OK if we are resolving for
 205                 * reading.
 206                 */
 207                if (lstat(path, &st) < 0) {
 208                        struct ref_list *list = get_packed_refs();
 209                        while (list) {
 210                                if (!strcmp(ref, list->name)) {
 211                                        hashcpy(sha1, list->sha1);
 212                                        if (flag)
 213                                                *flag |= REF_ISPACKED;
 214                                        return ref;
 215                                }
 216                                list = list->next;
 217                        }
 218                        if (reading || errno != ENOENT)
 219                                return NULL;
 220                        hashclr(sha1);
 221                        return ref;
 222                }
 223
 224                /* Follow "normalized" - ie "refs/.." symlinks by hand */
 225                if (S_ISLNK(st.st_mode)) {
 226                        len = readlink(path, buffer, sizeof(buffer)-1);
 227                        if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 228                                buffer[len] = 0;
 229                                strcpy(ref_buffer, buffer);
 230                                ref = ref_buffer;
 231                                if (flag)
 232                                        *flag |= REF_ISSYMREF;
 233                                continue;
 234                        }
 235                }
 236
 237                /*
 238                 * Anything else, just open it and try to use it as
 239                 * a ref
 240                 */
 241                fd = open(path, O_RDONLY);
 242                if (fd < 0)
 243                        return NULL;
 244                len = read(fd, buffer, sizeof(buffer)-1);
 245                close(fd);
 246
 247                /*
 248                 * Is it a symbolic ref?
 249                 */
 250                if (len < 4 || memcmp("ref:", buffer, 4))
 251                        break;
 252                buf = buffer + 4;
 253                len -= 4;
 254                while (len && isspace(*buf))
 255                        buf++, len--;
 256                while (len && isspace(buf[len-1]))
 257                        len--;
 258                buf[len] = 0;
 259                memcpy(ref_buffer, buf, len + 1);
 260                ref = ref_buffer;
 261                if (flag)
 262                        *flag |= REF_ISSYMREF;
 263        }
 264        if (len < 40 || get_sha1_hex(buffer, sha1))
 265                return NULL;
 266        return ref;
 267}
 268
 269int create_symref(const char *ref_target, const char *refs_heads_master)
 270{
 271        const char *lockpath;
 272        char ref[1000];
 273        int fd, len, written;
 274        const char *git_HEAD = git_path("%s", ref_target);
 275
 276#ifndef NO_SYMLINK_HEAD
 277        if (prefer_symlink_refs) {
 278                unlink(git_HEAD);
 279                if (!symlink(refs_heads_master, git_HEAD))
 280                        return 0;
 281                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 282        }
 283#endif
 284
 285        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 286        if (sizeof(ref) <= len) {
 287                error("refname too long: %s", refs_heads_master);
 288                return -1;
 289        }
 290        lockpath = mkpath("%s.lock", git_HEAD);
 291        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
 292        written = write(fd, ref, len);
 293        close(fd);
 294        if (written != len) {
 295                unlink(lockpath);
 296                error("Unable to write to %s", lockpath);
 297                return -2;
 298        }
 299        if (rename(lockpath, git_HEAD) < 0) {
 300                unlink(lockpath);
 301                error("Unable to create %s", git_HEAD);
 302                return -3;
 303        }
 304        if (adjust_shared_perm(git_HEAD)) {
 305                unlink(lockpath);
 306                error("Unable to fix permissions on %s", lockpath);
 307                return -4;
 308        }
 309        return 0;
 310}
 311
 312int read_ref(const char *ref, unsigned char *sha1)
 313{
 314        if (resolve_ref(ref, sha1, 1, NULL))
 315                return 0;
 316        return -1;
 317}
 318
 319static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 320                           void *cb_data)
 321{
 322        int retval;
 323        struct ref_list *packed = get_packed_refs();
 324        struct ref_list *loose = get_loose_refs();
 325
 326        while (packed && loose) {
 327                struct ref_list *entry;
 328                int cmp = strcmp(packed->name, loose->name);
 329                if (!cmp) {
 330                        packed = packed->next;
 331                        continue;
 332                }
 333                if (cmp > 0) {
 334                        entry = loose;
 335                        loose = loose->next;
 336                } else {
 337                        entry = packed;
 338                        packed = packed->next;
 339                }
 340                if (strncmp(base, entry->name, trim))
 341                        continue;
 342                if (is_null_sha1(entry->sha1))
 343                        continue;
 344                if (!has_sha1_file(entry->sha1)) {
 345                        error("%s does not point to a valid object!", entry->name);
 346                        continue;
 347                }
 348                retval = fn(entry->name + trim, entry->sha1,
 349                            entry->flag, cb_data);
 350                if (retval)
 351                        return retval;
 352        }
 353
 354        packed = packed ? packed : loose;
 355        while (packed) {
 356                if (!strncmp(base, packed->name, trim)) {
 357                        retval = fn(packed->name + trim, packed->sha1,
 358                                    packed->flag, cb_data);
 359                        if (retval)
 360                                return retval;
 361                }
 362                packed = packed->next;
 363        }
 364        return 0;
 365}
 366
 367int head_ref(each_ref_fn fn, void *cb_data)
 368{
 369        unsigned char sha1[20];
 370        int flag;
 371
 372        if (resolve_ref("HEAD", sha1, 1, &flag))
 373                return fn("HEAD", sha1, flag, cb_data);
 374        return 0;
 375}
 376
 377int for_each_ref(each_ref_fn fn, void *cb_data)
 378{
 379        return do_for_each_ref("refs/", fn, 0, cb_data);
 380}
 381
 382int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 383{
 384        return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 385}
 386
 387int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 388{
 389        return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 390}
 391
 392int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 393{
 394        return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 395}
 396
 397/* NEEDSWORK: This is only used by ssh-upload and it should go; the
 398 * caller should do resolve_ref or read_ref like everybody else.  Or
 399 * maybe everybody else should use get_ref_sha1() instead of doing
 400 * read_ref().
 401 */
 402int get_ref_sha1(const char *ref, unsigned char *sha1)
 403{
 404        if (check_ref_format(ref))
 405                return -1;
 406        return read_ref(mkpath("refs/%s", ref), sha1);
 407}
 408
 409int delete_ref(const char *refname, unsigned char *sha1)
 410{
 411        struct ref_lock *lock;
 412        int err, i, ret = 0;
 413
 414        lock = lock_any_ref_for_update(refname, sha1);
 415        if (!lock)
 416                return 1;
 417        i = strlen(lock->lk->filename) - 5; /* .lock */
 418        lock->lk->filename[i] = 0;
 419        err = unlink(lock->lk->filename);
 420        if (err) {
 421                ret = 1;
 422                error("unlink(%s) failed: %s",
 423                      lock->lk->filename, strerror(errno));
 424        }
 425        lock->lk->filename[i] = '.';
 426
 427        err = unlink(lock->log_file);
 428        if (err && errno != ENOENT)
 429                fprintf(stderr, "warning: unlink(%s) failed: %s",
 430                        lock->log_file, strerror(errno));
 431
 432        invalidate_cached_refs();
 433        return ret;
 434}
 435
 436/*
 437 * Make sure "ref" is something reasonable to have under ".git/refs/";
 438 * We do not like it if:
 439 *
 440 * - any path component of it begins with ".", or
 441 * - it has double dots "..", or
 442 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 443 * - it ends with a "/".
 444 */
 445
 446static inline int bad_ref_char(int ch)
 447{
 448        return (((unsigned) ch) <= ' ' ||
 449                ch == '~' || ch == '^' || ch == ':' ||
 450                /* 2.13 Pattern Matching Notation */
 451                ch == '?' || ch == '*' || ch == '[');
 452}
 453
 454int check_ref_format(const char *ref)
 455{
 456        int ch, level;
 457        const char *cp = ref;
 458
 459        level = 0;
 460        while (1) {
 461                while ((ch = *cp++) == '/')
 462                        ; /* tolerate duplicated slashes */
 463                if (!ch)
 464                        return -1; /* should not end with slashes */
 465
 466                /* we are at the beginning of the path component */
 467                if (ch == '.' || bad_ref_char(ch))
 468                        return -1;
 469
 470                /* scan the rest of the path component */
 471                while ((ch = *cp++) != 0) {
 472                        if (bad_ref_char(ch))
 473                                return -1;
 474                        if (ch == '/')
 475                                break;
 476                        if (ch == '.' && *cp == '.')
 477                                return -1;
 478                }
 479                level++;
 480                if (!ch) {
 481                        if (level < 2)
 482                                return -1; /* at least of form "heads/blah" */
 483                        return 0;
 484                }
 485        }
 486}
 487
 488static struct ref_lock *verify_lock(struct ref_lock *lock,
 489        const unsigned char *old_sha1, int mustexist)
 490{
 491        if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 492                error("Can't verify ref %s", lock->ref_name);
 493                unlock_ref(lock);
 494                return NULL;
 495        }
 496        if (hashcmp(lock->old_sha1, old_sha1)) {
 497                error("Ref %s is at %s but expected %s", lock->ref_name,
 498                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 499                unlock_ref(lock);
 500                return NULL;
 501        }
 502        return lock;
 503}
 504
 505static int remove_empty_dir_recursive(char *path, int len)
 506{
 507        DIR *dir = opendir(path);
 508        struct dirent *e;
 509        int ret = 0;
 510
 511        if (!dir)
 512                return -1;
 513        if (path[len-1] != '/')
 514                path[len++] = '/';
 515        while ((e = readdir(dir)) != NULL) {
 516                struct stat st;
 517                int namlen;
 518                if ((e->d_name[0] == '.') &&
 519                    ((e->d_name[1] == 0) ||
 520                     ((e->d_name[1] == '.') && e->d_name[2] == 0)))
 521                        continue; /* "." and ".." */
 522
 523                namlen = strlen(e->d_name);
 524                if ((len + namlen < PATH_MAX) &&
 525                    strcpy(path + len, e->d_name) &&
 526                    !lstat(path, &st) &&
 527                    S_ISDIR(st.st_mode) &&
 528                    remove_empty_dir_recursive(path, len + namlen))
 529                        continue; /* happy */
 530
 531                /* path too long, stat fails, or non-directory still exists */
 532                ret = -1;
 533                break;
 534        }
 535        closedir(dir);
 536        if (!ret) {
 537                path[len] = 0;
 538                ret = rmdir(path);
 539        }
 540        return ret;
 541}
 542
 543static int remove_empty_directories(char *file)
 544{
 545        /* we want to create a file but there is a directory there;
 546         * if that is an empty directory (or a directory that contains
 547         * only empty directories), remove them.
 548         */
 549        char path[PATH_MAX];
 550        int len = strlen(file);
 551
 552        if (len >= PATH_MAX) /* path too long ;-) */
 553                return -1;
 554        strcpy(path, file);
 555        return remove_empty_dir_recursive(path, len);
 556}
 557
 558static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1)
 559{
 560        char *ref_file;
 561        const char *orig_ref = ref;
 562        struct ref_lock *lock;
 563        struct stat st;
 564        int last_errno = 0;
 565        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 566
 567        lock = xcalloc(1, sizeof(struct ref_lock));
 568        lock->lock_fd = -1;
 569
 570        ref = resolve_ref(ref, lock->old_sha1, mustexist, NULL);
 571        if (!ref && errno == EISDIR) {
 572                /* we are trying to lock foo but we used to
 573                 * have foo/bar which now does not exist;
 574                 * it is normal for the empty directory 'foo'
 575                 * to remain.
 576                 */
 577                ref_file = git_path("%s", orig_ref);
 578                if (remove_empty_directories(ref_file)) {
 579                        last_errno = errno;
 580                        error("there are still refs under '%s'", orig_ref);
 581                        goto error_return;
 582                }
 583                ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, NULL);
 584        }
 585        if (!ref) {
 586                last_errno = errno;
 587                error("unable to resolve reference %s: %s",
 588                        orig_ref, strerror(errno));
 589                goto error_return;
 590        }
 591        lock->lk = xcalloc(1, sizeof(struct lock_file));
 592
 593        lock->ref_name = xstrdup(ref);
 594        lock->log_file = xstrdup(git_path("logs/%s", ref));
 595        ref_file = git_path("%s", ref);
 596        lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 597
 598        if (safe_create_leading_directories(ref_file)) {
 599                last_errno = errno;
 600                error("unable to create directory for %s", ref_file);
 601                goto error_return;
 602        }
 603        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 604
 605        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 606
 607 error_return:
 608        unlock_ref(lock);
 609        errno = last_errno;
 610        return NULL;
 611}
 612
 613struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 614{
 615        char refpath[PATH_MAX];
 616        if (check_ref_format(ref))
 617                return NULL;
 618        strcpy(refpath, mkpath("refs/%s", ref));
 619        return lock_ref_sha1_basic(refpath, old_sha1);
 620}
 621
 622struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 623{
 624        return lock_ref_sha1_basic(ref, old_sha1);
 625}
 626
 627void unlock_ref(struct ref_lock *lock)
 628{
 629        if (lock->lock_fd >= 0) {
 630                close(lock->lock_fd);
 631                /* Do not free lock->lk -- atexit() still looks at them */
 632                if (lock->lk)
 633                        rollback_lock_file(lock->lk);
 634        }
 635        free(lock->ref_name);
 636        free(lock->log_file);
 637        free(lock);
 638}
 639
 640static int log_ref_write(struct ref_lock *lock,
 641        const unsigned char *sha1, const char *msg)
 642{
 643        int logfd, written, oflags = O_APPEND | O_WRONLY;
 644        unsigned maxlen, len;
 645        char *logrec;
 646        const char *committer;
 647
 648        if (log_all_ref_updates) {
 649                if (safe_create_leading_directories(lock->log_file) < 0)
 650                        return error("unable to create directory for %s",
 651                                lock->log_file);
 652                oflags |= O_CREAT;
 653        }
 654
 655        logfd = open(lock->log_file, oflags, 0666);
 656        if (logfd < 0) {
 657                if (!log_all_ref_updates && errno == ENOENT)
 658                        return 0;
 659                return error("Unable to append to %s: %s",
 660                        lock->log_file, strerror(errno));
 661        }
 662
 663        committer = git_committer_info(1);
 664        if (msg) {
 665                maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 666                logrec = xmalloc(maxlen);
 667                len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 668                        sha1_to_hex(lock->old_sha1),
 669                        sha1_to_hex(sha1),
 670                        committer,
 671                        msg);
 672        }
 673        else {
 674                maxlen = strlen(committer) + 2*40 + 4;
 675                logrec = xmalloc(maxlen);
 676                len = snprintf(logrec, maxlen, "%s %s %s\n",
 677                        sha1_to_hex(lock->old_sha1),
 678                        sha1_to_hex(sha1),
 679                        committer);
 680        }
 681        written = len <= maxlen ? write(logfd, logrec, len) : -1;
 682        free(logrec);
 683        close(logfd);
 684        if (written != len)
 685                return error("Unable to append to %s", lock->log_file);
 686        return 0;
 687}
 688
 689int write_ref_sha1(struct ref_lock *lock,
 690        const unsigned char *sha1, const char *logmsg)
 691{
 692        static char term = '\n';
 693
 694        if (!lock)
 695                return -1;
 696        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
 697                unlock_ref(lock);
 698                return 0;
 699        }
 700        if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 701            write(lock->lock_fd, &term, 1) != 1
 702                || close(lock->lock_fd) < 0) {
 703                error("Couldn't write %s", lock->lk->filename);
 704                unlock_ref(lock);
 705                return -1;
 706        }
 707        invalidate_cached_refs();
 708        if (log_ref_write(lock, sha1, logmsg) < 0) {
 709                unlock_ref(lock);
 710                return -1;
 711        }
 712        if (commit_lock_file(lock->lk)) {
 713                error("Couldn't set %s", lock->ref_name);
 714                unlock_ref(lock);
 715                return -1;
 716        }
 717        lock->lock_fd = -1;
 718        unlock_ref(lock);
 719        return 0;
 720}
 721
 722int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 723{
 724        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 725        char *tz_c;
 726        int logfd, tz;
 727        struct stat st;
 728        unsigned long date;
 729        unsigned char logged_sha1[20];
 730
 731        logfile = git_path("logs/%s", ref);
 732        logfd = open(logfile, O_RDONLY, 0);
 733        if (logfd < 0)
 734                die("Unable to read log %s: %s", logfile, strerror(errno));
 735        fstat(logfd, &st);
 736        if (!st.st_size)
 737                die("Log %s is empty.", logfile);
 738        logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 739        close(logfd);
 740
 741        lastrec = NULL;
 742        rec = logend = logdata + st.st_size;
 743        while (logdata < rec) {
 744                if (logdata < rec && *(rec-1) == '\n')
 745                        rec--;
 746                lastgt = NULL;
 747                while (logdata < rec && *(rec-1) != '\n') {
 748                        rec--;
 749                        if (*rec == '>')
 750                                lastgt = rec;
 751                }
 752                if (!lastgt)
 753                        die("Log %s is corrupt.", logfile);
 754                date = strtoul(lastgt + 1, &tz_c, 10);
 755                if (date <= at_time) {
 756                        if (lastrec) {
 757                                if (get_sha1_hex(lastrec, logged_sha1))
 758                                        die("Log %s is corrupt.", logfile);
 759                                if (get_sha1_hex(rec + 41, sha1))
 760                                        die("Log %s is corrupt.", logfile);
 761                                if (hashcmp(logged_sha1, sha1)) {
 762                                        tz = strtoul(tz_c, NULL, 10);
 763                                        fprintf(stderr,
 764                                                "warning: Log %s has gap after %s.\n",
 765                                                logfile, show_rfc2822_date(date, tz));
 766                                }
 767                        }
 768                        else if (date == at_time) {
 769                                if (get_sha1_hex(rec + 41, sha1))
 770                                        die("Log %s is corrupt.", logfile);
 771                        }
 772                        else {
 773                                if (get_sha1_hex(rec + 41, logged_sha1))
 774                                        die("Log %s is corrupt.", logfile);
 775                                if (hashcmp(logged_sha1, sha1)) {
 776                                        tz = strtoul(tz_c, NULL, 10);
 777                                        fprintf(stderr,
 778                                                "warning: Log %s unexpectedly ended on %s.\n",
 779                                                logfile, show_rfc2822_date(date, tz));
 780                                }
 781                        }
 782                        munmap((void*)logdata, st.st_size);
 783                        return 0;
 784                }
 785                lastrec = rec;
 786        }
 787
 788        rec = logdata;
 789        while (rec < logend && *rec != '>' && *rec != '\n')
 790                rec++;
 791        if (rec == logend || *rec == '\n')
 792                die("Log %s is corrupt.", logfile);
 793        date = strtoul(rec + 1, &tz_c, 10);
 794        tz = strtoul(tz_c, NULL, 10);
 795        if (get_sha1_hex(logdata, sha1))
 796                die("Log %s is corrupt.", logfile);
 797        munmap((void*)logdata, st.st_size);
 798        fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 799                logfile, show_rfc2822_date(date, tz));
 800        return 0;
 801}