xref: /csrg-svn/lib/libc/gen/unvis.c (revision 41932)

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)unvis.c	1.1 (Berkeley) 05/15/90";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <ctype.h>
#include <vis.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 */

/*
 * unvis - decode characters previously encoded by vis
 */
unvis(cp, c, astate, flag)
	u_char *cp, c;
	int *astate, 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 = 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);
		}
		*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)
		 */
		return (UNVIS_ERROR);
	}
}

/*
 * strvis - visually encode characters from src into dst
 *
 *	If len >= 0, encodes exactly len chars from src (including NULL's).
 *	Otherwise, stops before first NULL in src.  In all cases, dst is
 *	NULL terminated.
 *
 *	Dst must be 4 times the size of src to account for possible
 *	expansion.  The length of dst, not including the trailing NULL,
 *	is returned.
 */
strvis(dst, src, len, flag)
	register char *dst, *src;
	register int len;
{
	char *start = dst;

	for (;;) {
		if (len > 0) {
			if (len-- == 0)
				break;
		} else if (!*src)
			break;
		dst = vis(dst, *src, flag, *(src+1));
		src++;
	}

	return (dst - start);
}