/*      $OpenBSD: log.c,v 1.12 2017/04/18 01:45:35 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 <libgen.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(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, "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(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;
        }
        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(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(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(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(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(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,
                    "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 (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(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,
                    "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(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,
            "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 (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(SCR *sp, char *file, int line)
{
        EXF *ep;

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

#if defined(DEBUG) && 0
static void
log_trace(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