/*      $NetBSD: genget.c,v 1.14 2018/12/14 23:42:39 christos Exp $     */

/*-
* Copyright (c) 1991, 1993
*      The Regents of the University of California.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)genget.c    8.2 (Berkeley) 5/30/95";
#else
__RCSID("$NetBSD: genget.c,v 1.14 2018/12/14 23:42:39 christos Exp $");
#endif
#endif /* not lint */


#include <ctype.h>
#include "misc.h"

#define LOWER(x) (isupper((unsigned char)x) ? tolower((unsigned char)x) : (x))
/*
* The prefix function returns 0 if *s1 is not a prefix
* of *s2.  If *s1 exactly matches *s2, the negative of
* the length is returned.  If *s1 is a prefix of *s2,
* the length of *s1 is returned.
*/
int
isprefix(const char *s1, const char *s2)
{
       const char *os1;
       char c1, c2;

       if (*s1 == '\0')
               return(-1);
       os1 = s1;
       c1 = *s1;
       c2 = *s2;
       while (LOWER(c1) == LOWER(c2)) {
               if (c1 == '\0')
                       break;
               c1 = *++s1;
               c2 = *++s2;
       }
       return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
}

static char *ambiguous;         /* special return value for command routines */

char **
genget(const char *name,                /* name to match */
       char    **table,        /* name entry in table */
       int     stlen)
{
       register char **c, **found;
       register int n;

       if (name == 0)
           return 0;

       found = 0;
       for (c = table; *c != 0; c = (char **)((char *)c + stlen)) {
               if ((n = isprefix(name, *c)) == 0)
                       continue;
               if (n < 0)              /* exact match */
                       return(c);
               if (found)
                       return(&ambiguous);
               found = c;
       }
       return(found);
}

/*
* Function call version of Ambiguous()
*/
int
Ambiguous(void *s)
{
       return(s == &ambiguous);
}