Systemd/tdb/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.
*/

#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>
#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 = malloc(len);
	if (!ret) {
		fprintf(stderr,"Out of memory!\n");
		exit(1);
	}
	strncpy(ret, name, len);
	strncat(ret, suffix, len);
	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_new->name);
		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)
{
	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);
		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);
		return 1;
	}

	/* create the new tdb */
	unlink(tmp_name);
	tdb_new = tdb_open(tmp_name, tdb->header.hash_size, 
			   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_new->fd);

	/* 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);
	}

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

	return 0;
}