log.c

早期freebsd实现

	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.
 */
int
log_backward(sp, ep, rp)
	SCR *sp;
	EXF *ep;
	MARK *rp;
{
	DBT key, data;
	LMARK lm;
	MARK m;
	recno_t lno;
	int didop;
	u_char *p;

	if (F_ISSET(ep, F_NOLOG)) {
		msgq(sp, M_ERR,
		    "Logging not being performed, undo not possible.");
		return (1);
	}

	if (ep->l_cur == 1) {
		msgq(sp, M_BERR, "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 (file_dline(sp, ep, lno))
				goto err;
			++sp->rptlines[L_DELETED];
			break;
		case LOG_LINE_DELETE:
			didop = 1;
			memmove(&lno, p + sizeof(u_char), sizeof(recno_t));
			if (file_iline(sp, ep, 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 (file_sline(sp, ep, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			++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, ep, 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.
 */
int
log_setline(sp, ep)
	SCR *sp;
	EXF *ep;
{
	DBT key, data;
	LMARK lm;
	MARK m;
	recno_t lno;
	u_char *p;

	if (F_ISSET(ep, F_NOLOG)) {
		msgq(sp, M_ERR,
		    "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 &&
			    file_sline(sp, ep, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			++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, ep, 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.
 */
int
log_forward(sp, ep, rp)
	SCR *sp;
	EXF *ep;
	MARK *rp;
{
	DBT key, data;
	LMARK lm;
	MARK m;
	recno_t lno;
	int didop;
	u_char *p;

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

	if (ep->l_cur == ep->l_high) {
		msgq(sp, M_BERR, "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 (file_iline(sp, ep, 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 (file_dline(sp, ep, 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 (file_sline(sp, ep, lno, p + sizeof(u_char) +
			    sizeof(recno_t), data.size - sizeof(u_char) -
			    sizeof(recno_t)))
				goto err;
			++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, ep, lm.name, &m, 0))
				goto err;
			break;
		default:
			abort();
		}
	}

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

#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