/*      $KAME: advcap.c,v 1.11 2003/05/19 09:46:50 keiichi Exp $        */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983 The Regents of the University of California.
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

/*
 * remcap - routines for dealing with the remote host data base
 *
 * derived from termcap
 */
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include "pathnames.h"

#ifndef BUFSIZ
#define BUFSIZ          1024
#endif
#define MAXHOP          32              /* max number of tc= indirections */

#define tgetent         agetent
#define tnchktc         anchktc
#define tnamatch        anamatch
#define tgetnum         agetnum
#define tgetflag        agetflag
#define tgetstr         agetstr

#if 0
#define V_TERMCAP       "REMOTE"
#define V_TERM          "HOST"
#endif

/*
 * termcap - routines for dealing with the terminal capability data base
 *
 * BUG:         Should use a "last" pointer in tbuf, so that searching
 *              for capabilities alphabetically would not be a n**2/2
 *              process when large numbers of capabilities are given.
 * Note:        If we add a last pointer now we will screw up the
 *              tc capability. We really should compile termcap.
 *
 * Essentially all the work here is scanning and decoding escapes
 * in string capabilities.  We don't use stdio because the editor
 * doesn't, and because living w/o it is not hard.
 */

static  char *tbuf;
static  int hopcount;   /* detect infinite loops in termcap, init 0 */

extern const char *conffile;

int tgetent(char *, char *);
int getent(char *, char *, const char *);
int tnchktc(void);
int tnamatch(char *);
static char *tskip(char *);
int64_t tgetnum(char *);
int tgetflag(char *);
char *tgetstr(char *, char **);
static char *tdecode(char *, char **);

/*
 * Get an entry for terminal name in buffer bp,
 * from the termcap file.  Parse is very rudimentary;
 * we just notice escaped newlines.
 */
int
tgetent(char *bp, char *name)
{
        return (getent(bp, name, conffile));
}

int
getent(char *bp, char *name, const char *cfile)
{
        int c;
        int i = 0, cnt = 0;
        char ibuf[BUFSIZ];
        char *cp;
        int tf;

        tbuf = bp;
        tf = 0;
        /*
         * TERMCAP can have one of two things in it. It can be the
         * name of a file to use instead of /etc/termcap. In this
         * case it better start with a "/". Or it can be an entry to
         * use so we don't have to read the file. In this case it
         * has to already have the newlines crunched out.
         */
        if (cfile && *cfile)
                tf = open(cfile, O_RDONLY);

        if (tf < 0) {
                syslog(LOG_INFO,
                       "<%s> open: %s", __func__, strerror(errno));
                return (-2);
        }
        for (;;) {
                cp = bp;
                for (;;) {
                        if (i == cnt) {
                                cnt = read(tf, ibuf, BUFSIZ);
                                if (cnt <= 0) {
                                        close(tf);
                                        return (0);
                                }
                                i = 0;
                        }
                        c = ibuf[i++];
                        if (c == '\n') {
                                if (cp > bp && cp[-1] == '\\') {
                                        cp--;
                                        continue;
                                }
                                break;
                        }
                        if (cp >= bp + BUFSIZ - 1) {
                                write(STDERR_FILENO, "Remcap entry too long\n",
                                    22);
                                break;
                        } else
                                *cp++ = c;
                }
                *cp = 0;

                /*
                 * The real work for the match.
                 */
                if (tnamatch(name)) {
                        close(tf);
                        return (tnchktc());
                }
        }
}

/*
 * tnchktc: check the last entry, see if it's tc=xxx. If so,
 * recursively find xxx and append that entry (minus the names)
 * to take the place of the tc=xxx entry. This allows termcap
 * entries to say "like an HP2621 but doesn't turn on the labels".
 * Note that this works because of the left to right scan.
 */
int
tnchktc(void)
{
        char *p, *q;
        char tcname[16];        /* name of similar terminal */
        char tcbuf[BUFSIZ];
        char *holdtbuf = tbuf;
        int l;

        p = tbuf + strlen(tbuf) - 2;    /* before the last colon */
        while (*--p != ':')
                if (p < tbuf) {
                        write(STDERR_FILENO, "Bad remcap entry\n", 18);
                        return (0);
                }
        p++;
        /* p now points to beginning of last field */
        if (p[0] != 't' || p[1] != 'c')
                return (1);
        strlcpy(tcname, p + 3, sizeof tcname);
        q = tcname;
        while (*q && *q != ':')
                q++;
        *q = 0;
        if (++hopcount > MAXHOP) {
                write(STDERR_FILENO, "Infinite tc= loop\n", 18);
                return (0);
        }
        if (getent(tcbuf, tcname, conffile) != 1) {
                return (0);
        }
        for (q = tcbuf; *q++ != ':'; )
                ;
        l = p - holdtbuf + strlen(q);
        if (l > BUFSIZ) {
                write(STDERR_FILENO, "Remcap entry too long\n", 23);
                q[BUFSIZ - (p-holdtbuf)] = 0;
        }
        strcpy(p, q);
        tbuf = holdtbuf;
        return (1);
}

/*
 * Tnamatch deals with name matching.  The first field of the termcap
 * entry is a sequence of names separated by |'s, so we compare
 * against each such name.  The normal : terminator after the last
 * name (before the first field) stops us.
 */
int
tnamatch(char *np)
{
        char *Np, *Bp;

        Bp = tbuf;
        if (*Bp == '#')
                return (0);
        for (;;) {
                for (Np = np; *Np && *Bp == *Np; Bp++, Np++)
                        continue;
                if (*Np == 0 && (*Bp == '|' || *Bp == ':' || *Bp == 0))
                        return (1);
                while (*Bp && *Bp != ':' && *Bp != '|')
                        Bp++;
                if (*Bp == 0 || *Bp == ':')
                        return (0);
                Bp++;
        }
}

/*
 * Skip to the next field.  Notice that this is very dumb, not
 * knowing about \: escapes or any such.  If necessary, :'s can be put
 * into the termcap file in octal.
 */
static char *
tskip(char *bp)
{
        int dquote;

        dquote = 0;
        while (*bp) {
                switch (*bp) {
                case ':':
                        if (!dquote)
                                goto breakbreak;
                        else
                                bp++;
                        break;
                case '\\':
                        bp++;
                        if (isdigit(*bp)) {
                                while (isdigit(*bp++))
                                        ;
                        } else
                                bp++;
                case '"':
                        dquote = (dquote ? 1 : 0);
                        bp++;
                        break;
                default:
                        bp++;
                        break;
                }
        }
breakbreak:
        if (*bp == ':')
                bp++;
        return (bp);
}

/*
 * Return the (numeric) option id.
 * Numeric options look like
 *      li#80
 * i.e. the option string is separated from the numeric value by
 * a # character.  If the option is not found we return -1.
 * Note that we handle octal numbers beginning with 0.
 */
int64_t
tgetnum(char *id)
{
        int64_t i;
        int base;
        char *bp = tbuf;

        for (;;) {
                bp = tskip(bp);
                if (*bp == 0)
                        return (-1);
                if (strncmp(bp, id, strlen(id)) != 0)
                        continue;
                bp += strlen(id);
                if (*bp == '@')
                        return (-1);
                if (*bp != '#')
                        continue;
                bp++;
                base = 10;
                if (*bp == '0')
                        base = 8;
                i = 0;
                while (isdigit(*bp))
                        i *= base, i += *bp++ - '0';
                return (i);
        }
}

/*
 * Handle a flag option.
 * Flag options are given "naked", i.e. followed by a : or the end
 * of the buffer.  Return 1 if we find the option, or 0 if it is
 * not given.
 */
int
tgetflag(char *id)
{
        char *bp = tbuf;

        for (;;) {
                bp = tskip(bp);
                if (!*bp)
                        return (0);
                if (strncmp(bp, id, strlen(id)) == 0) {
                        bp += strlen(id);
                        if (!*bp || *bp == ':')
                                return (1);
                        else if (*bp == '@')
                                return (0);
                }
        }
}

/*
 * Get a string valued option.
 * These are given as
 *      cl=^Z
 * Much decoding is done on the strings, and the strings are
 * placed in area, which is a ref parameter which is updated.
 * No checking on area overflow.
 */
char *
tgetstr(char *id, char **area)
{
        char *bp = tbuf;

        for (;;) {
                bp = tskip(bp);
                if (!*bp)
                        return (0);
                if (strncmp(bp, id, strlen(id)) != 0)
                        continue;
                bp += strlen(id);
                if (*bp == '@')
                        return (0);
                if (*bp != '=')
                        continue;
                bp++;
                return (tdecode(bp, area));
        }
}

/*
 * Tdecode does the grung work to decode the
 * string capability escapes.
 */
static char *
tdecode(char *str, char **area)
{
        char *cp;
        int c;
        const char *dp;
        int i;
        char term;

        term = ':';
        cp = *area;
again:
        if (*str == '"') {
                term = '"';
                str++;
        }
        while ((c = *str++) && c != term) {
                switch (c) {

                case '^':
                        c = *str++ & 037;
                        break;

                case '\\':
                        dp = "E\033^^\\\\::n\nr\rt\tb\bf\f\"\"";
                        c = *str++;
nextc:
                        if (*dp++ == c) {
                                c = *dp++;
                                break;
                        }
                        dp++;
                        if (*dp)
                                goto nextc;
                        if (isdigit(c)) {
                                c -= '0', i = 2;
                                do
                                        c <<= 3, c |= *str++ - '0';
                                while (--i && isdigit(*str));
                        }
                        break;
                }
                *cp++ = c;
        }
        if (c == term && term != ':') {
                term = ':';
                goto again;
        }
        *cp++ = 0;
        str = *area;
        *area = cp;
        return (str);
}