lib/libtelnet/genget.c

   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  * @(#)genget.c 8.2 (Berkeley) 5/30/95
  34  * $FreeBSD: src/crypto/telnet/libtelnet/genget.c,v 1.2.8.2 2002/04/13 10:59:07 markm Exp $
  35  */
  36
  37 #include <sys/_null.h>
  38 #include <ctype.h>
  39
  40 #include "misc-proto.h"
  41
  42 #define LOWER(x) (isupper(x) ? tolower(x) : (x))
  43 /*
  44  * The prefix function returns 0 if *s1 is not a prefix
  45  * of *s2.  If *s1 exactly matches *s2, the negative of
  46  * the length is returned.  If *s1 is a prefix of *s2,
  47  * the length of *s1 is returned.
  48  */
  49 int
  50 isprefix(char *s1, const char *s2)
  51 {
  52         char *os1;
  53         char c1, c2;
  54
  55         if (*s1 == '\0')
  56                 return(-1);
  57         os1 = s1;
  58         c1 = *s1;
  59         c2 = *s2;
  60         while (LOWER(c1) == LOWER(c2)) {
  61                 if (c1 == '\0')
  62                         break;
  63                 c1 = *++s1;
  64                 c2 = *++s2;
  65         }
  66         return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
  67 }
  68
  69 static char *ambiguous;         /* special return value for command routines */
  70
  71 char **
  72 genget(char *name, char **table, int stlen)
  73 {
  74         char **c, **found;
  75         int n;
  76
  77         if (name == NULL)
  78             return 0;
  79
  80         found = NULL;
  81         for (c = table; *c != NULL; c = (char **)((char *)c + stlen)) {
  82                 if ((n = isprefix(name, *c)) == 0)
  83                         continue;
  84                 if (n < 0)              /* exact match */
  85                         return(c);
  86                 if (found)
  87                         return(&ambiguous);
  88                 found = c;
  89         }
  90         return(found);
  91 }
  92
  93 /*
  94  * Function call version of Ambiguous()
  95  */
  96 int
  97 Ambiguous(char **s)
  98 {
  99         return(s == &ambiguous);
 100 }