/*
 * Copyright 2001 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved. The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/*
 * remcap - routines for dealing with the remote host data base
 *
 * derived from termcap
 */
#ifdef USG
#include <sys/types.h>
#include <fcntl.h>      /* for O_RDONLY */
#else
#include <sys/file.h>   /* for O_RDONLY */
#include <ctype.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include "tip.h"

#ifndef BUFSIZ
#define BUFSIZ          1024
#endif
#define MAXHOP          32              /* max number of tc= indirections */
#define SYSREMOTE       "/etc/remote"   /* system remote file */

#define tgetent         rgetent
#define tnchktc         rnchktc
#define tnamatch        rnamatch
#define tgetnum         rgetnum
#define tgetflag        rgetflag
#define tgetstr         rgetstr
#define E_TERMCAP       RM = SYSREMOTE
#define V_TERMCAP       "REMOTE"
#define V_TERM          "HOST"

/*
 * 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 */
static char *remotefile;

static char     *tskip(char *);
static char     *tdecode(char *, char **);

char    *tgetstr(char *, char **);
int     getent(char *, char *, char *, int);
int     tnchktc(void);
int     tnamatch(char *);

extern void     myperm(void);
extern void     userperm(void);

/*
 * If we use a user specified entry to get the device name,
 * we need to open the device as the user.
 */
int trusted_device = 0;

/*
 * 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, int len)
{
        char lbuf[BUFSIZ], *cp, *p;
        int rc1, rc2;

        trusted_device = 1;

        remotefile = cp = getenv(V_TERMCAP);
        if (cp == (char *)0 || strcmp(cp, SYSREMOTE) == 0) {
                remotefile = cp = SYSREMOTE;
                return (getent(bp, name, cp, len));
        } else {
                if ((rc1 = getent(bp, name, cp, len)) != 1)
                        *bp = '\0';
                remotefile = cp = SYSREMOTE;
                rc2 = getent(lbuf, name, cp, sizeof (lbuf));
                if (rc1 != 1 && rc2 != 1)
                        return (rc2);
                if (rc2 == 1) {
                        p = lbuf;
                        if (rc1 == 1)
                                while (*p++ != ':')
                                        ;
                        if (strlen(bp) + strlen(p) >= len) {
                                (void) write(2, "Remcap entry too long\n", 23);
                                return (-1);
                        }
                        (void) strcat(bp, p);
                }
                tbuf = bp;
                return (1);
        }
}

int
getent(char *bp, char *name, char *cp, int len)
{
        int c;
        int i = 0, cnt = 0;
        char ibuf[BUFSIZ], *cp2;
        int tf;
        int safe = 1; /* reset only when we open the user's $REMOTE */

        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 (cp && *cp) {
                if (*cp != '/') {
                        cp2 = getenv(V_TERM);
                        if (cp2 == (char *)0 || strcmp(name, cp2) == 0) {
                                if (strstr(cp, "dv=") != 0)
                                        trusted_device = 0;
                                (void) strncpy(bp, cp, len-1);
                                bp[len-1] = '\0';
                                return (tnchktc());
                        } else
                                tf = open(E_TERMCAP, O_RDONLY);
                } else {
                        /* open SYSREMOTE as uucp, other files as user */
                        safe = strcmp(cp, SYSREMOTE) == 0;
                        if (!safe)
                                userperm();
                        tf = open(RM = cp, O_RDONLY);
                        if (!safe)
                                myperm();
                }
        }
        if (tf == 0)
                tf = open(E_TERMCAP, O_RDONLY);
        if (tf < 0)
                return (-1);
        for (;;) {
                cp = bp;
                for (;;) {
                        if (i == cnt) {
                                cnt = read(tf, ibuf, BUFSIZ);
                                if (cnt <= 0) {
                                        (void) close(tf);
                                        return (0);
                                }
                                i = 0;
                        }
                        c = ibuf[i++];
                        if (c == '\n') {
                                if (cp > bp && cp[-1] == '\\') {
                                        cp--;
                                        continue;
                                }
                                break;
                        }
                        if (cp >= bp+len) {
                                (void) write(2, "Remcap entry too long\n", 23);
                                break;
                        } else
                                *cp++ = c;
                }
                *cp = 0;

                /*
                 * The real work for the match.
                 */
                if (tnamatch(name)) {
                        /*
                         * if a dv= entry is obtained from $REMOTE,
                         * switch off trusted_device status
                         */
                        if (!safe && strstr(bp, "dv=") != 0)
                                trusted_device = 0;
                        (void) 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[64];        /* 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) {
                        (void) write(2, "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);
        (void) strlcpy(tcname, p+3, sizeof (tcname));
        q = tcname;
        while (*q && *q != ':')
                q++;
        *q = 0;
        if (++hopcount > MAXHOP) {
                (void) write(2, "Infinite tc= loop\n", 18);
                return (0);
        }
        if (getent(tcbuf, tcname, remotefile, sizeof (tcbuf)) != 1) {
                if (strcmp(remotefile, SYSREMOTE) == 0)
                        return (0);
                else if (getent(tcbuf, tcname, SYSREMOTE, sizeof (tcbuf)) != 1)
                        return (0);
        }
        for (q = tcbuf; *q++ != ':'; )
                ;
        l = p - holdtbuf + strlen(q);
        if (l > BUFSIZ) {
                (void) write(2, "Remcap entry too long\n", 23);
                q[BUFSIZ - (p-holdtbuf)] = 0;
        }
        (void) 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)
{

        while (*bp && *bp != ':')
                bp++;
        if (*bp == ':') {
                do {
                        bp++;
                        while (isspace(*bp))
                                bp++;
                } while (*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.
 */
int
tgetnum(char *id)
{
        int i, base;
        char *bp = tbuf;

        for (;;) {
                bp = tskip(bp);
                if (*bp == 0)
                        return (-1);
                if (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
                        continue;
                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 (*bp++ == id[0] && *bp != 0 && *bp++ == id[1]) {
                        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 (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
                        continue;
                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;
        char *dp;
        int i;

        cp = *area;
        while ((c = *str++) != 0 && c != ':') {
                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;
        }
        *cp++ = 0;
        str = *area;
        *area = cp;
        return (str);
}