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      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
     35 static 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  */
     52 int
     53 isprefix(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 
     72 static char *ambiguous;		/* special return value for command routines */
     73 
     74 char **
     75 genget(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  */
    101 int
    102 Ambiguous(void *s)
    103 {
    104 	return(s == &ambiguous);
    105 }
    106