xref: /openbsd-src/usr.bin/telnet/genget.c (revision 29625f71f8480740478b31221eded302116f1615)

/*     $OpenBSD: genget.c,v 1.6 2019/07/11 05:11:16 deraadt Exp $  */

/*-
 * Copyright (c) 1991, 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. 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.
 */

/* $KTH: genget.c,v 1.6 1997/05/04 09:01:34 assar Exp $ */

#include <ctype.h>
#include "telnet_locl.h"

/*
 * The prefix function returns 0 if *s1 is not a prefix
 * of *s2.  If *s1 exactly matches *s2, the negative of
 * the length is returned.  If *s1 is a prefix of *s2,
 * the length of *s1 is returned.
 */
int
isprefix(char *s1, char *s2)
{
    char *os1;
    char c1, c2;

    if (*s1 == '\0')
	return(-1);
    os1 = s1;
    c1 = *s1;
    c2 = *s2;
    while (tolower((unsigned char)c1) == tolower((unsigned char)c2)) {
	if (c1 == '\0')
	    break;
	c1 = *++s1;
	c2 = *++s2;
    }
    return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
}

static char *ambiguous;		/* special return value for command routines */

char **
genget(char *name, char **table, int stlen)
     /* name to match */
     /* name entry in table */
{
    char **c, **found;
    int n;

    if (name == NULL)
	return (NULL);

    found = NULL;
    for (c = table; *c != NULL; c = (char **)((char *)c + stlen)) {
	if ((n = isprefix(name, *c)) == 0)
	    continue;
	if (n < 0)		/* exact match */
	    return(c);
	if (found)
	    return(&ambiguous);
	found = c;
    }
    return(found);
}

/*
 * Function call version of Ambiguous()
 */
int
Ambiguous(void *s)
{
    return((char **)s == &ambiguous);
}