/*
 * Copyright (c) 2001-2005 Greg Becker.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: dits.h,v 1.2 2004/04/05 02:53:27 greg Exp $
 */

#ifndef DITS_MAIN_H
#define DITS_MAIN_H

typedef uint32_t			crc32_t;

extern void crc32_init(void);
extern crc32_t crc32(u_char *buf, int len, crc32_t crc);

/* Preload shift register, per CRC-32 spec.
 */
#define CRC32_PRELOAD			(0xffffffff)

#define DITS_MAGIC			(0x12345678)

#define DITS_MIN(a, b)			((a) < (b) ? (a) : (b))

/* A record defines the data stored in each sector.  Each record has
 * a unique ID which is used to detect missing or multiple instances
 * that might occur due to system faults.
 */
typedef struct {
	int64_t ctime;			/* Time test bed was created */
	int64_t mtime;			/* Time of last modification */
	int64_t nsectors;		/* # of sectors in the test bed */
	int64_t pid;			/* Proc that last updated the sector */
	int64_t id;			/* Record unique ID */
	int64_t src;			/* Swap source sector */
	int64_t dst;			/* Swap destination sector */
	int32_t len;			/* Swap length (in sectors) */
	int32_t nswaps;			/* # of swaps */
	int32_t spare1;
	int32_t spare2;
} record_t;


/* Flags for sector_t.flags;
 */
#define DITS_FRTCK	(0x0001)	/* Initialized with run time ck file */

/* Each sector_t must occupy exactly one disk sector.  rec[0] is
 * the active record, while rec[1] is the rollback record, which is
 * to say it contains the contents of rec[0] prior to the last swap.
 * rec[1] is used to implement an inexpensive transaction log so that
 * in the event of a failure (e.g., system crash or abnormal child
 * termination) the transaction (i.e., the swap) can be rolled back.
 */
typedef struct {
	uint32_t magic;			/* DITS_MAGIC */
	uint32_t revision;		/* From svnrev2num() */
	uint64_t flags;
	record_t rec[2];		/* The current and saved records */
	char session[32];		/* Session name */
	uint64_t randupd;		/* Random update # */
	uint64_t kscratch;		/* Kernel scratch area */
	char payload[300];		/* Pad sector_t out to 512-bytes */
	crc32_t crc;			/* CRC of the entire record */
} sector_t;

extern off_t oseek;

extern void eprintf(char *fmt, ...);

#endif /* DITS_MAIN_H */