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rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

/*	$OpenBSD: log.c,v 1.5 2009/10/27 23:59:47 deraadt Exp $	*/

/*-
 * Copyright (c) 1992, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *	Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <bitstring.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "common.h"

/*
 * The log consists of records, each containing a type byte and a variable
 * length byte string, as follows:
 *
 *	LOG_CURSOR_INIT		MARK
 *	LOG_CURSOR_END		MARK
 *	LOG_LINE_APPEND 	recno_t		char *
 *	LOG_LINE_DELETE		recno_t		char *
 *	LOG_LINE_INSERT		recno_t		char *
 *	LOG_LINE_RESET_F	recno_t		char *
 *	LOG_LINE_RESET_B	recno_t		char *
 *	LOG_MARK		LMARK
 *
 * We do before image physical logging.  This means that the editor layer
 * MAY NOT modify records in place, even if simply deleting or overwriting
 * characters.  Since the smallest unit of logging is a line, we're using
 * up lots of space.  This may eventually have to be reduced, probably by
 * doing logical logging, which is a much cooler database phrase.
 *
 * The implementation of the historic vi 'u' command, using roll-forward and
 * roll-back, is simple.  Each set of changes has a LOG_CURSOR_INIT record,
 * followed by a number of other records, followed by a LOG_CURSOR_END record.
 * LOG_LINE_RESET records come in pairs.  The first is a LOG_LINE_RESET_B
 * record, and is the line before the change.  The second is LOG_LINE_RESET_F,
 * and is the line after the change.  Roll-back is done by backing up to the
 * first LOG_CURSOR_INIT record before a change.  Roll-forward is done in a
 * similar fashion.
 *
 * The 'U' command is implemented by rolling backward to a LOG_CURSOR_END
 * record for a line different from the current one.  It should be noted that
 * this means that a subsequent 'u' command will make a change based on the
 * new position of the log's cursor.  This is okay, and, in fact, historic vi
 * behaved that way.
 */

static int	log_cursor1(SCR *, int);
static void	log_err(SCR *, char *, int);
#if defined(DEBUG) && 0
static void	log_trace(SCR *, char *, recno_t, u_char *);
#endif

/* Try and restart the log on failure, i.e. if we run out of memory. */
#define	LOG_ERR {							\
	log_err(sp, __FILE__, __LINE__);				\
	return (1);							\
}

/*
 * log_init --
 *	Initialize the logging subsystem.
 *
 * PUBLIC: int log_init(SCR *, EXF *);
 */
int
log_init(sp, ep)
	SCR *sp;
	EXF *ep;
{
	/*
	 * !!!
	 * ep MAY NOT BE THE SAME AS sp->ep, DON'T USE THE LATTER.
	 *
	 * Initialize the buffer.  The logging subsystem has its own
	 * buffers because the global ones are almost by definition
	 * going to be in use when the log runs.
	 */
	ep->l_lp = NULL;
	ep->l_len = 0;
	ep->l_cursor.lno = 1;		/* XXX Any valid recno. */
	ep->l_cursor.cno = 0;
	ep->l_high = ep->l_cur = 1;

	ep->log = dbopen(NULL, O_CREAT | O_NONBLOCK | O_RDWR,
	    S_IRUSR | S_IWUSR, DB_RECNO, NULL);
	if (ep->log == NULL) {
		msgq(sp, M_SYSERR, "009|Log file");
		F_SET(ep, F_NOLOG);
		return (1);
	}

	return (0);
}

/*
 * log_end --
 *	Close the logging subsystem.
 *
 * PUBLIC: int log_end(SCR *, EXF *);
 */
int
log_end(sp, ep)
	SCR *sp;
	EXF *ep;
{
	/*
	 * !!!
	 * ep MAY NOT BE THE SAME AS sp->ep, DON'T USE THE LATTER.
	 */
	if (ep->log != NULL) {
		(void)(ep->log->close)(ep->log);
		ep->log = NULL;
	}
	if (ep->l_lp != NULL) {
		free(ep->l_lp);
		ep->l_lp = NULL;
	}
	ep->l_len = 0;
	ep->l_cursor.lno = 1;		/* XXX Any valid recno. */
	ep->l_cursor.cno = 0;
	ep->l_high = ep->l_cur = 1;
	return (0);
}

/*
 * log_cursor --
 *	Log the current cursor position, starting an event.
 *
 * PUBLIC: int log_cursor(SCR *);
 */
int
log_cursor(sp)
	SCR *sp;
{
	EXF *ep;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG))
		return (0);

	/*
	 * If any changes were made since the last cursor init,
	 * put out the ending cursor record.
	 */
	if (ep->l_cursor.lno == OOBLNO) {
		ep->l_cursor.lno = sp->lno;
		ep->l_cursor.cno = sp->cno;
		return (log_cursor1(sp, LOG_CURSOR_END));
	}
	ep->l_cursor.lno = sp->lno;
	ep->l_cursor.cno = sp->cno;
	return (0);
}

/*
 * log_cursor1 --
 *	Actually push a cursor record out.
 */
static int
log_cursor1(sp, type)
	SCR *sp;
	int type;
{
	DBT data, key;
	EXF *ep;

	ep = sp->ep;
	BINC_RET(sp, ep->l_lp, ep->l_len, sizeof(u_char) + sizeof(MARK));
	ep->l_lp[0] = type;
	memmove(ep->l_lp + sizeof(u_char), &ep->l_cursor, sizeof(MARK));

	key.data = &ep->l_cur;
	key.size = sizeof(recno_t);
	data.data = ep->l_lp;
	data.size = sizeof(u_char) + sizeof(MARK);
	if (ep->log->put(ep->log, &key, &data, 0) == -1)
		LOG_ERR;

#if defined(DEBUG) && 0
	TRACE(sp, "%lu: %s: %u/%u\n", ep->l_cur,
	    type == LOG_CURSOR_INIT ? "log_cursor_init" : "log_cursor_end",
	    sp->lno, sp->cno);
#endif
	/* Reset high water mark. */
	ep->l_high = ++ep->l_cur;

	return (0);
}

/*
 * log_line --
 *	Log a line change.
 *
 * PUBLIC: int log_line(SCR *, recno_t, u_int);
 */
int
log_line(sp, lno, action)
	SCR *sp;
	recno_t lno;
	u_int action;
{
	DBT data, key;
	EXF *ep;
	size_t len;
	char *lp;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG))
		return (0);

	/*
	 * XXX
	 *
	 * Kluge for vi.  Clear the EXF undo flag so that the
	 * next 'u' command does a roll-back, regardless.
	 */
	F_CLR(ep, F_UNDO);

	/* Put out one initial cursor record per set of changes. */
	if (ep->l_cursor.lno != OOBLNO) {
		if (log_cursor1(sp, LOG_CURSOR_INIT))
			return (1);
		ep->l_cursor.lno = OOBLNO;
	}

	/*
	 * Put out the changes.  If it's a LOG_LINE_RESET_B call, it's a
	 * special case, avoid the caches.  Also, if it fails and it's
	 * line 1, it just means that the user started with an empty file,
	 * so fake an empty length line.
	 */
	if (action == LOG_LINE_RESET_B) {
		if (db_get(sp, lno, DBG_NOCACHE, &lp, &len)) {
			if (lno != 1) {
				db_err(sp, lno);
				return (1);
			}
			len = 0;
			lp = "";
		}
	} else
		if (db_get(sp, lno, DBG_FATAL, &lp, &len))
			return (1);
	BINC_RET(sp,
	    ep->l_lp, ep->l_len, len + sizeof(u_char) + sizeof(recno_t));
	ep->l_lp[0] = action;
	memmove(ep->l_lp + sizeof(u_char), &lno, sizeof(recno_t));
	memmove(ep->l_lp + sizeof(u_char) + sizeof(recno_t), lp, len);

	key.data = &ep->l_cur;
	key.size = sizeof(recno_t);
	data.data = ep->l_lp;
	data.size = len + sizeof(u_char) + sizeof(recno_t);
	if (ep->log->put(ep->log, &key, &data, 0) == -1)
		LOG_ERR;

#if defined(DEBUG) && 0
	switch (action) {
	case LOG_LINE_APPEND:
		TRACE(sp, "%u: log_line: append: %lu {%u}\n",
		    ep->l_cur, lno, len);
		break;
	case LOG_LINE_DELETE:
		TRACE(sp, "%lu: log_line: delete: %lu {%u}\n",
		    ep->l_cur, lno, len);
		break;
	case LOG_LINE_INSERT:
		TRACE(sp, "%lu: log_line: insert: %lu {%u}\n",
		    ep->l_cur, lno, len);
		break;
	case LOG_LINE_RESET_F:
		TRACE(sp, "%lu: log_line: reset_f: %lu {%u}\n",
		    ep->l_cur, lno, len);
		break;
	case LOG_LINE_RESET_B:
		TRACE(sp, "%lu: log_line: reset_b: %lu {%u}\n",
		    ep->l_cur, lno, len);
		break;
	}
#endif
	/* Reset high water mark. */
	ep->l_high = ++ep->l_cur;

	return (0);
}

/*
 * log_mark --
 *	Log a mark position.  For the log to work, we assume that there
 *	aren't any operations that just put out a log record -- this
 *	would mean that undo operations would only reset marks, and not
 *	cause any other change.
 *
 * PUBLIC: int log_mark(SCR *, LMARK *);
 */
int
log_mark(sp, lmp)
	SCR *sp;
	LMARK *lmp;
{
	DBT data, key;
	EXF *ep;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG))
		return (0);

	/* Put out one initial cursor record per set of changes. */
	if (ep->l_cursor.lno != OOBLNO) {
		if (log_cursor1(sp, LOG_CURSOR_INIT))
			return (1);
		ep->l_cursor.lno = OOBLNO;
	}

	BINC_RET(sp, ep->l_lp,
	    ep->l_len, sizeof(u_char) + sizeof(LMARK));
	ep->l_lp[0] = LOG_MARK;
	memmove(ep->l_lp + sizeof(u_char), lmp, sizeof(LMARK));

	key.data = &ep->l_cur;
	key.size = sizeof(recno_t);
	data.data = ep->l_lp;
	data.size = sizeof(u_char) + sizeof(LMARK);
	if (ep->log->put(ep->log, &key, &data, 0) == -1)
		LOG_ERR;

#if defined(DEBUG) && 0
	TRACE(sp, "%lu: mark %c: %lu/%u\n",
	    ep->l_cur, lmp->name, lmp->lno, lmp->cno);
#endif
	/* Reset high water mark. */
	ep->l_high = ++ep->l_cur;
	return (0);
}

/*
 * Log_backward --
 *	Roll the log backward one operation.
 *
 * PUBLIC: int log_backward(SCR *, MARK *);
 */
int
log_backward(sp, rp)
	SCR *sp;
	MARK *rp;
{
	DBT key, data;
	EXF *ep;
	LMARK lm;
	MARK m;
	recno_t lno;
	int didop;
	u_char *p;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG)) {
		msgq(sp, M_ERR,
		    "010|Logging not being performed, undo not possible");
		return (1);
	}

	if (ep->l_cur == 1) {
		msgq(sp, M_BERR, "011|No changes to undo");
		return (1);
	}

	F_SET(ep, F_NOLOG);		/* Turn off logging. */

	key.data = &ep->l_cur;		/* Initialize db request. */
	key.size = sizeof(recno_t);
	for (didop = 0;;) {
		--ep->l_cur;
		if (ep->log->get(ep->log, &key, &data, 0))
			LOG_ERR;
#if defined(DEBUG) && 0
		log_trace(sp, "log_backward", ep->l_cur, data.data);
#endif
		switch (*(p = (u_char *)data.data)) {
		case LOG_CURSOR_INIT:
			if (didop) {
				memmove(rp, p + sizeof(u_char), sizeof(MARK));
				F_CLR(ep, F_NOLOG);
				return (0);
			}
			break;
		case LOG_CURSOR_END:
			break;
		case LOG_LINE_APPEND:
		case LOG_LINE_INSERT:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_delete(sp, lno))
				goto err;
			++sp->rptlines[L_DELETED];
			break;
		case LOG_LINE_DELETE:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_insert(sp, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			++sp->rptlines[L_ADDED];
			break;
		case LOG_LINE_RESET_F:
			break;
		case LOG_LINE_RESET_B:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_set(sp, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			if (sp->rptlchange != lno) {
				sp->rptlchange = lno;
				++sp->rptlines[L_CHANGED];
			}
			break;
		case LOG_MARK:
			didop = 1;
			memmove(&lm, p + sizeof(u_char), sizeof(LMARK));
			m.lno = lm.lno;
			m.cno = lm.cno;
			if (mark_set(sp, lm.name, &m, 0))
				goto err;
			break;
		default:
			abort();
		}
	}

err:	F_CLR(ep, F_NOLOG);
	return (1);
}

/*
 * Log_setline --
 *	Reset the line to its original appearance.
 *
 * XXX
 * There's a bug in this code due to our not logging cursor movements
 * unless a change was made.  If you do a change, move off the line,
 * then move back on and do a 'U', the line will be restored to the way
 * it was before the original change.
 *
 * PUBLIC: int log_setline(SCR *);
 */
int
log_setline(sp)
	SCR *sp;
{
	DBT key, data;
	EXF *ep;
	LMARK lm;
	MARK m;
	recno_t lno;
	u_char *p;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG)) {
		msgq(sp, M_ERR,
		    "012|Logging not being performed, undo not possible");
		return (1);
	}

	if (ep->l_cur == 1)
		return (1);

	F_SET(ep, F_NOLOG);		/* Turn off logging. */

	key.data = &ep->l_cur;		/* Initialize db request. */
	key.size = sizeof(recno_t);

	for (;;) {
		--ep->l_cur;
		if (ep->log->get(ep->log, &key, &data, 0))
			LOG_ERR;
#if defined(DEBUG) && 0
		log_trace(sp, "log_setline", ep->l_cur, data.data);
#endif
		switch (*(p = (u_char *)data.data)) {
		case LOG_CURSOR_INIT:
			memmove(&m, p + sizeof(u_char), sizeof(MARK));
			if (m.lno != sp->lno || ep->l_cur == 1) {
				F_CLR(ep, F_NOLOG);
				return (0);
			}
			break;
		case LOG_CURSOR_END:
			memmove(&m, p + sizeof(u_char), sizeof(MARK));
			if (m.lno != sp->lno) {
				++ep->l_cur;
				F_CLR(ep, F_NOLOG);
				return (0);
			}
			break;
		case LOG_LINE_APPEND:
		case LOG_LINE_INSERT:
		case LOG_LINE_DELETE:
		case LOG_LINE_RESET_F:
			break;
		case LOG_LINE_RESET_B:
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (lno == sp->lno &&
			    db_set(sp, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			if (sp->rptlchange != lno) {
				sp->rptlchange = lno;
				++sp->rptlines[L_CHANGED];
			}
		case LOG_MARK:
			memmove(&lm, p + sizeof(u_char), sizeof(LMARK));
			m.lno = lm.lno;
			m.cno = lm.cno;
			if (mark_set(sp, lm.name, &m, 0))
				goto err;
			break;
		default:
			abort();
		}
	}

err:	F_CLR(ep, F_NOLOG);
	return (1);
}

/*
 * Log_forward --
 *	Roll the log forward one operation.
 *
 * PUBLIC: int log_forward(SCR *, MARK *);
 */
int
log_forward(sp, rp)
	SCR *sp;
	MARK *rp;
{
	DBT key, data;
	EXF *ep;
	LMARK lm;
	MARK m;
	recno_t lno;
	int didop;
	u_char *p;

	ep = sp->ep;
	if (F_ISSET(ep, F_NOLOG)) {
		msgq(sp, M_ERR,
	    "013|Logging not being performed, roll-forward not possible");
		return (1);
	}

	if (ep->l_cur == ep->l_high) {
		msgq(sp, M_BERR, "014|No changes to re-do");
		return (1);
	}

	F_SET(ep, F_NOLOG);		/* Turn off logging. */

	key.data = &ep->l_cur;		/* Initialize db request. */
	key.size = sizeof(recno_t);
	for (didop = 0;;) {
		++ep->l_cur;
		if (ep->log->get(ep->log, &key, &data, 0))
			LOG_ERR;
#if defined(DEBUG) && 0
		log_trace(sp, "log_forward", ep->l_cur, data.data);
#endif
		switch (*(p = (u_char *)data.data)) {
		case LOG_CURSOR_END:
			if (didop) {
				++ep->l_cur;
				memmove(rp, p + sizeof(u_char), sizeof(MARK));
				F_CLR(ep, F_NOLOG);
				return (0);
			}
			break;
		case LOG_CURSOR_INIT:
			break;
		case LOG_LINE_APPEND:
		case LOG_LINE_INSERT:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_insert(sp, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			++sp->rptlines[L_ADDED];
			break;
		case LOG_LINE_DELETE:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_delete(sp, lno))
				goto err;
			++sp->rptlines[L_DELETED];
			break;
		case LOG_LINE_RESET_B:
			break;
		case LOG_LINE_RESET_F:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (db_set(sp, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			if (sp->rptlchange != lno) {
				sp->rptlchange = lno;
				++sp->rptlines[L_CHANGED];
			}
			break;
		case LOG_MARK:
			didop = 1;
			memmove(&lm, p + sizeof(u_char), sizeof(LMARK));
			m.lno = lm.lno;
			m.cno = lm.cno;
			if (mark_set(sp, lm.name, &m, 0))
				goto err;
			break;
		default:
			abort();
		}
	}

err:	F_CLR(ep, F_NOLOG);
	return (1);
}

/*
 * log_err --
 *	Try and restart the log on failure, i.e. if we run out of memory.
 */
static void
log_err(sp, file, line)
	SCR *sp;
	char *file;
	int line;
{
	EXF *ep;

	msgq(sp, M_SYSERR, "015|%s/%d: log put error", tail(file), line);
	ep = sp->ep;
	(void)ep->log->close(ep->log);
	if (!log_init(sp, ep))
		msgq(sp, M_ERR, "267|Log restarted");
}

#if defined(DEBUG) && 0
static void
log_trace(sp, msg, rno, p)
	SCR *sp;
	char *msg;
	recno_t rno;
	u_char *p;
{
	LMARK lm;
	MARK m;
	recno_t lno;

	switch (*p) {
	case LOG_CURSOR_INIT:
		memmove(&m, p + sizeof(u_char), sizeof(MARK));
		TRACE(sp, "%lu: %s:  C_INIT: %u/%u\n", rno, msg, m.lno, m.cno);
		break;
	case LOG_CURSOR_END:
		memmove(&m, p + sizeof(u_char), sizeof(MARK));
		TRACE(sp, "%lu: %s:   C_END: %u/%u\n", rno, msg, m.lno, m.cno);
		break;
	case LOG_LINE_APPEND:
		memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
		TRACE(sp, "%lu: %s:  APPEND: %lu\n", rno, msg, lno);
		break;
	case LOG_LINE_INSERT:
		memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
		TRACE(sp, "%lu: %s:  INSERT: %lu\n", rno, msg, lno);
		break;
	case LOG_LINE_DELETE:
		memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
		TRACE(sp, "%lu: %s:  DELETE: %lu\n", rno, msg, lno);
		break;
	case LOG_LINE_RESET_F:
		memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
		TRACE(sp, "%lu: %s: RESET_F: %lu\n", rno, msg, lno);
		break;
	case LOG_LINE_RESET_B:
		memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
		TRACE(sp, "%lu: %s: RESET_B: %lu\n", rno, msg, lno);
		break;
	case LOG_MARK:
		memmove(&lm, p + sizeof(u_char), sizeof(LMARK));
		TRACE(sp,
		    "%lu: %s:    MARK: %u/%u\n", rno, msg, lm.lno, lm.cno);
		break;
	default:
		abort();
	}
}
#endif