genget.c revision 84305 
1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/contrib/telnet/libtelnet/genget.c 84305 2001-10-01 16:04:55Z markm $");
36
37#ifndef lint
38#if 0
39static const char sccsid[] = "@(#)genget.c	8.2 (Berkeley) 5/30/95";
40#endif
41#endif /* not lint */
42
43
44#include <ctype.h>
45
46#define	LOWER(x) (isupper(x) ? tolower(x) : (x))
47/*
48 * The prefix function returns 0 if *s1 is not a prefix
49 * of *s2.  If *s1 exactly matches *s2, the negative of
50 * the length is returned.  If *s1 is a prefix of *s2,
51 * the length of *s1 is returned.
52 */
53int
54isprefix(char *s1, char *s2)
55{
56	char *os1;
57	char c1, c2;
58
59	if (*s1 == '\0')
60		return(-1);
61	os1 = s1;
62	c1 = *s1;
63	c2 = *s2;
64	while (LOWER(c1) == LOWER(c2)) {
65		if (c1 == '\0')
66			break;
67		c1 = *++s1;
68		c2 = *++s2;
69	}
70	return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
71}
72
73static char *ambiguous;		/* special return value for command routines */
74
75char **
76genget(char *name, char **table, int stlen)
77{
78	char **c, **found;
79	int n;
80
81	if (name == 0)
82	    return 0;
83
84	found = 0;
85	for (c = table; *c != 0; c = (char **)((char *)c + stlen)) {
86		if ((n = isprefix(name, *c)) == 0)
87			continue;
88		if (n < 0)		/* exact match */
89			return(c);
90		if (found)
91			return(&ambiguous);
92		found = c;
93	}
94	return(found);
95}
96
97/*
98 * Function call version of Ambiguous()
99 */
100int
101Ambiguous(char *s)
102{
103	return((char **)s == &ambiguous);
104}
105