xref: /illumos-gate/usr/src/cmd/cmd-inet/usr.bin/telnet/genget.c (revision 8b80e8cb6855118d46f605e91b5ed4ce83417395)
1 /*
2  * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
3  * Use is subject to license terms.
4  */
5 
6 #pragma ident	"%Z%%M%	%I%	%E% SMI"
7 
8 /*
9  * Copyright (c) 1991, 1993
10  *	The Regents of the University of California.  All rights reserved.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by the University of
23  *	California, Berkeley and its contributors.
24  * 4. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  */
40 
41 #ifndef lint
42 static char sccsid[] = "@(#)genget.c	8.1 (Berkeley) 6/4/93";
43 #endif /* not lint */
44 
45 #include <ctype.h>
46 #include <sys/types.h>
47 
48 #define	LOWER(x) (isupper(x) ? tolower(x) : (x))
49 
50 static char *ambiguous;		/* special return value for command routines */
51 
52 /*
53  * The prefix function returns 0 if *s1 is not a prefix
54  * of *s2.  If *s1 exactly matches *s2, the negative of
55  * the length is returned.  If *s1 is a prefix of *s2,
56  * the length of *s1 is returned.
57  */
58 int
59 isprefix(char *s1, char *s2)
60 {
61 	char *os1;
62 	char c1, c2;
63 
64 	if (*s1 == '\0')
65 		return (-1);
66 	os1 = s1;
67 	c1 = *s1;
68 	c2 = *s2;
69 	while (LOWER(c1) == LOWER(c2)) {
70 		if (c1 == '\0')
71 			break;
72 		c1 = *++s1;
73 		c2 = *++s2;
74 	}
75 	return (*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
76 }
77 
78 
79 /*
80  * Get an entry from the table, from what might be a prefix
81  *
82  * name		= name to match
83  * table	= name entry in table
84  */
85 char **
86 genget(char *name, char **table, int stlen)
87 {
88 	register char **c, **found;
89 	register int n;
90 
91 	if (name == 0)
92 	    return (0);
93 
94 	found = 0;
95 	/*LINTED*/
96 	for (c = table; *c != NULL; c = (char **)((char *)c + stlen)) {
97 		if ((n = isprefix(name, *c)) == 0)
98 			continue;
99 		if (n < 0)		/* exact match */
100 			return (c);
101 		if (found)
102 			return (&ambiguous);
103 		found = c;
104 	}
105 	return (found);
106 }
107 
108 /*
109  * Function call version of Ambiguous()
110  */
111 boolean_t
112 Ambiguous(void *s)
113 {
114 	return ((char **)s == &ambiguous);
115 }
116