1/*	$NetBSD: genget.c,v 1.14 2018/12/14 23:42:39 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)genget.c	8.2 (Berkeley) 5/30/95";
36#else
37__RCSID("$NetBSD: genget.c,v 1.14 2018/12/14 23:42:39 christos Exp $");
38#endif
39#endif /* not lint */
40
41
42#include <ctype.h>
43#include "misc.h"
44
45#define	LOWER(x) (isupper((unsigned char)x) ? tolower((unsigned char)x) : (x))
46/*
47 * The prefix function returns 0 if *s1 is not a prefix
48 * of *s2.  If *s1 exactly matches *s2, the negative of
49 * the length is returned.  If *s1 is a prefix of *s2,
50 * the length of *s1 is returned.
51 */
52int
53isprefix(const char *s1, const char *s2)
54{
55	const char *os1;
56	char c1, c2;
57
58	if (*s1 == '\0')
59		return(-1);
60	os1 = s1;
61	c1 = *s1;
62	c2 = *s2;
63	while (LOWER(c1) == LOWER(c2)) {
64		if (c1 == '\0')
65			break;
66		c1 = *++s1;
67		c2 = *++s2;
68	}
69	return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
70}
71
72static char *ambiguous;		/* special return value for command routines */
73
74char **
75genget(const char *name,		/* name to match */
76	char	**table,	/* name entry in table */
77	int	stlen)
78{
79	register char **c, **found;
80	register int n;
81
82	if (name == 0)
83	    return 0;
84
85	found = 0;
86	for (c = table; *c != 0; c = (char **)((char *)c + stlen)) {
87		if ((n = isprefix(name, *c)) == 0)
88			continue;
89		if (n < 0)		/* exact match */
90			return(c);
91		if (found)
92			return(&ambiguous);
93		found = c;
94	}
95	return(found);
96}
97
98/*
99 * Function call version of Ambiguous()
100 */
101int
102Ambiguous(void *s)
103{
104	return(s == &ambiguous);
105}
106