text: /*	$Id: strunvis.c,v 1.5 2001/11/24 20:26:01 offe Exp $	*/
  /*	$NetBSD: unvis.c,v 1.16 1999/09/20 04:39:06 lukem Exp $	*/
  
  /*-
   * Copyright (c) 1989, 1993
   *	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. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. 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.
   */
  
  #if defined(SOLARIS) || defined(SUNOS4) || defined(LINUX) || defined(AIX)
  
  #include "sys.h"
  
  /*
   * decode driven by state machine
   */
  #define	S_GROUND	0	/* haven't seen escape char */
  #define	S_START		1	/* start decoding special sequence */
  #define	S_META		2	/* metachar started (M) */
  #define	S_META1		3	/* metachar more, regular char (-) */
  #define	S_CTRL		4	/* control char started (^) */
  #define	S_OCTAL2	5	/* octal digit 2 */
  #define	S_OCTAL3	6	/* octal digit 3 */
  
  #define	isoctal(c)	(((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
  
  /*
   * unvis - decode characters previously encoded by vis
   */
  int
  unvis(char *cp, int c, int *astate, int flag)
  {
  
  	if (flag & UNVIS_END) {
  		if (*astate == S_OCTAL2 || *astate == S_OCTAL3) {
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		} 
  		return (*astate == S_GROUND ? UNVIS_NOCHAR : UNVIS_SYNBAD);
  	}
  
  	switch (*astate) {
  
  	case S_GROUND:
  		*cp = 0;
  		if (c == '\\') {
  			*astate = S_START;
  			return (0);
  		} 
  		*cp = c;
  		return (UNVIS_VALID);
  
  	case S_START:
  		switch(c) {
  		case '\\':
  			*cp = c;
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case '0': case '1': case '2': case '3':
  		case '4': case '5': case '6': case '7':
  			*cp = (c - '0');
  			*astate = S_OCTAL2;
  			return (0);
  		case 'M':
  			*cp = (char)0200;
  			*astate = S_META;
  			return (0);
  		case '^':
  			*astate = S_CTRL;
  			return (0);
  		case 'n':
  			*cp = '\n';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'r':
  			*cp = '\r';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'b':
  			*cp = '\b';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'a':
  			*cp = '\007';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'v':
  			*cp = '\v';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 't':
  			*cp = '\t';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'f':
  			*cp = '\f';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 's':
  			*cp = ' ';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case 'E':
  			*cp = '\033';
  			*astate = S_GROUND;
  			return (UNVIS_VALID);
  		case '\n':
  			/*
  			 * hidden newline
  			 */
  			*astate = S_GROUND;
  			return (UNVIS_NOCHAR);
  		case '$':
  			/*
  			 * hidden marker
  			 */
  			*astate = S_GROUND;
  			return (UNVIS_NOCHAR);
  		}
  		*astate = S_GROUND;
  		return (UNVIS_SYNBAD);
  		 
  	case S_META:
  		if (c == '-')
  			*astate = S_META1;
  		else if (c == '^')
  			*astate = S_CTRL;
  		else {
  			*astate = S_GROUND;
  			return (UNVIS_SYNBAD);
  		}
  		return (0);
  		 
  	case S_META1:
  		*astate = S_GROUND;
  		*cp |= c;
  		return (UNVIS_VALID);
  		 
  	case S_CTRL:
  		if (c == '?')
  			*cp |= 0177;
  		else
  			*cp |= c & 037;
  		*astate = S_GROUND;
  		return (UNVIS_VALID);
  
  	case S_OCTAL2:	/* second possible octal digit */
  		if (isoctal(c)) {
  			/* 
  			 * yes - and maybe a third 
  			 */
  			*cp = (*cp << 3) + (c - '0');
  			*astate = S_OCTAL3;	
  			return (0);
  		} 
  		/* 
  		 * no - done with current sequence, push back passed char 
  		 */
  		*astate = S_GROUND;
  		return (UNVIS_VALIDPUSH);
  
  	case S_OCTAL3:	/* third possible octal digit */
  		*astate = S_GROUND;
  		if (isoctal(c)) {
  			*cp = (*cp << 3) + (c - '0');
  			return (UNVIS_VALID);
  		}
  		/*
  		 * we were done, push back passed char
  		 */
  		return (UNVIS_VALIDPUSH);
  			
  	default:	
  		/* 
  		 * decoder in unknown state - (probably uninitialized) 
  		 */
  		*astate = S_GROUND;
  		return (UNVIS_SYNBAD);
  	}
  }
  
  /*
   * strunvis - decode src into dst 
   *
   *	Number of chars decoded into dst is returned, -1 on error.
   *	Dst is null terminated.
   */
  
  int
  strunvis(char *dst, const char *src)
  {
  	char c;
  	char *start = dst;
  	int state = 0;
  
  	while ((c = *src++) != '\0') {
  	again:
  		switch (unvis(dst, c, &state, 0)) {
  		case UNVIS_VALID:
  			dst++;
  			break;
  		case UNVIS_VALIDPUSH:
  			dst++;
  			goto again;
  		case 0:
  		case UNVIS_NOCHAR:
  			break;
  		default:
  			return (-1);
  		}
  	}
  	if (unvis(dst, c, &state, UNVIS_END) == UNVIS_VALID)
  		dst++;
  	*dst = '\0';
  	return (dst - start);
  }
  #endif
  