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genget.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1991 The Regents of the University of California.
      3  * 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 #ifndef lint
     35 static char sccsid[] = "@(#)genget.c	5.1 (Berkeley) 2/28/91";
     36 #endif /* not lint */
     37 
     38 
     39 #include <ctype.h>
     40 
     41 #define	LOWER(x) (isupper(x) ? tolower(x) : (x))
     42 /*
     43  * The prefix function returns 0 if *s1 is not a prefix
     44  * of *s2.  If *s1 exactly matches *s2, the negative of
     45  * the length is returned.  If *s1 is a prefix of *s2,
     46  * the length of *s1 is returned.
     47  */
     48 	int
     49 isprefix(s1, s2)
     50 	register char *s1, *s2;
     51 {
     52         register int n = 0;
     53         char *os1;
     54 	register char c1, c2;
     55 
     56         if (*s1 == '\0')
     57                 return(-1);
     58         os1 = s1;
     59 	c1 = *s1;
     60 	c2 = *s2;
     61         while (LOWER(c1) == LOWER(c2)) {
     62 		if (c1 == '\0')
     63 			break;
     64                 c1 = *++s1;
     65                 c2 = *++s2;
     66         }
     67         return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
     68 }
     69 
     70 static char *ambiguous;		/* special return value for command routines */
     71 
     72 	char **
     73 genget(name, table, stlen)
     74 	char	*name;		/* name to match */
     75 	char	**table;	/* name entry in table */
     76 	int	stlen;
     77 {
     78 	register char **c, **found;
     79 	register 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  */
    100 	int
    101 Ambiguous(s)
    102 	char *s;
    103 {
    104 	return((char **)s == &ambiguous);
    105 }
    106