usr/src/cmd/tip/remcap.c

/*
 * 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.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * 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>

#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"

char	*RM;

/*
 * 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);
}