source: branches/samba-3.3.x/source/lib/tdb/common/tdbback.c

/* 
   Unix SMB/CIFS implementation.
   low level tdb backup and restore utility
   Copyright (C) Andrew Tridgell              2002

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifdef STANDALONE
#if HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/mman.h>

#include <sys/stat.h>
#include <sys/time.h>
#include <ctype.h>
#include <signal.h>

#else
#include "includes.h"

#ifdef malloc
#undef malloc
#endif
                                                                                                                 
#ifdef realloc
#undef realloc
#endif
                                                                                                                 
#ifdef calloc
#undef calloc
#endif

#endif

#include "tdb.h"

static int failed;

char *add_suffix(const char *name, const char *suffix)
{
        char *ret;
        int len = strlen(name) + strlen(suffix) + 1;
        ret = (char *)malloc(len);
        if (!ret) {
                fprintf(stderr,"Out of memory!\n");
                exit(1);
        }
        snprintf(ret, len, "%s%s", name, suffix);
        return ret;
}

static int copy_fn(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, void *state)
{
        TDB_CONTEXT *tdb_new = (TDB_CONTEXT *)state;

        if (tdb_store(tdb_new, key, dbuf, TDB_INSERT) != 0) {
                fprintf(stderr,"Failed to insert into %s\n", tdb_name(tdb_new));
                failed = 1;
                return 1;
        }
        return 0;
}


static int test_fn(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, void *state)
{
        return 0;
}

/*
  carefully backup a tdb, validating the contents and
  only doing the backup if its OK
  this function is also used for restore
*/
int backup_tdb(const char *old_name, const char *new_name, int hash_size)
{
        TDB_CONTEXT *tdb;
        TDB_CONTEXT *tdb_new;
        char *tmp_name;
        struct stat st;
        int count1, count2;

        tmp_name = add_suffix(new_name, ".tmp");

        /* stat the old tdb to find its permissions */
        if (stat(old_name, &st) != 0) {
                perror(old_name);
                free(tmp_name);
                return 1;
        }

        /* open the old tdb */
        tdb = tdb_open(old_name, 0, 0, O_RDWR, 0);
        if (!tdb) {
                printf("Failed to open %s\n", old_name);
                free(tmp_name);
                return 1;
        }

        /* create the new tdb */
        unlink(tmp_name);
        tdb_new = tdb_open(tmp_name,
                           hash_size ? hash_size : tdb_hash_size(tdb),
                           TDB_DEFAULT, O_RDWR|O_CREAT|O_EXCL, 
                           st.st_mode & 0777);
        if (!tdb_new) {
                perror(tmp_name);
                free(tmp_name);
                return 1;
        }

        /* lock the old tdb */
        if (tdb_lockall(tdb) != 0) {
                fprintf(stderr,"Failed to lock %s\n", old_name);
                tdb_close(tdb);
                tdb_close(tdb_new);
                unlink(tmp_name);
                free(tmp_name);
                return 1;
        }

        failed = 0;

        /* traverse and copy */
        count1 = tdb_traverse(tdb, copy_fn, (void *)tdb_new);
        if (count1 < 0 || failed) {
                fprintf(stderr,"failed to copy %s\n", old_name);
                tdb_close(tdb);
                tdb_close(tdb_new);
                unlink(tmp_name);
                free(tmp_name);
                return 1;
        }

        /* close the old tdb */
        tdb_close(tdb);

        /* close the new tdb and re-open read-only */
        tdb_close(tdb_new);
        tdb_new = tdb_open(tmp_name, 0, TDB_DEFAULT, O_RDONLY, 0);
        if (!tdb_new) {
                fprintf(stderr,"failed to reopen %s\n", tmp_name);
                unlink(tmp_name);
                perror(tmp_name);
                free(tmp_name);
                return 1;
        }
        
        /* traverse the new tdb to confirm */
        count2 = tdb_traverse(tdb_new, test_fn, 0);
        if (count2 != count1) {
                fprintf(stderr,"failed to copy %s\n", old_name);
                tdb_close(tdb_new);
                unlink(tmp_name);
                free(tmp_name);
                return 1;
        }

        /* make sure the new tdb has reached stable storage */
        fsync(tdb_fd(tdb_new));

        /* close the new tdb and rename it to .bak */
        tdb_close(tdb_new);
        unlink(new_name);
        if (rename(tmp_name, new_name) != 0) {
                perror(new_name);
                free(tmp_name);
                return 1;
        }

        free(tmp_name);

        return 0;
}



/*
  verify a tdb and if it is corrupt then restore from *.bak
*/
int verify_tdb(const char *fname, const char *bak_name)
{
        TDB_CONTEXT *tdb;
        int count = -1;

        /* open the tdb */
        tdb = tdb_open(fname, 0, 0, O_RDONLY, 0);

        /* traverse the tdb, then close it */
        if (tdb) {
                count = tdb_traverse(tdb, test_fn, NULL);
                tdb_close(tdb);
        }

        /* count is < 0 means an error */
        if (count < 0) {
                printf("restoring %s\n", fname);
                return backup_tdb(bak_name, fname, 0);
        }

        printf("%s : %d records\n", fname, count);

        return 0;
}