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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)genget.c 8.2 (Berkeley) 5/30/95
  30  * $FreeBSD: src/crypto/telnet/libtelnet/genget.c,v 1.2.8.2 2002/04/13 10:59:07 markm Exp $
  31  */
  32
  33 #include <sys/_null.h>
  34 #include <ctype.h>
  35
  36 #include "misc-proto.h"
  37
  38 #define LOWER(x) (isupper(x) ? tolower(x) : (x))
  39 /*
  40  * The prefix function returns 0 if *s1 is not a prefix
  41  * of *s2.  If *s1 exactly matches *s2, the negative of
  42  * the length is returned.  If *s1 is a prefix of *s2,
  43  * the length of *s1 is returned.
  44  */
  45 int
  46 isprefix(char *s1, const char *s2)
  47 {
  48         char *os1;
  49         char c1, c2;
  50
  51         if (*s1 == '\0')
  52                 return(-1);
  53         os1 = s1;
  54         c1 = *s1;
  55         c2 = *s2;
  56         while (LOWER(c1) == LOWER(c2)) {
  57                 if (c1 == '\0')
  58                         break;
  59                 c1 = *++s1;
  60                 c2 = *++s2;
  61         }
  62         return(*s1 ? 0 : (*s2 ? (s1 - os1) : (os1 - s1)));
  63 }
  64
  65 static char *ambiguous;         /* special return value for command routines */
  66
  67 char **
  68 genget(char *name, char **table, int stlen)
  69 {
  70         char **c, **found;
  71         int n;
  72
  73         if (name == NULL)
  74             return 0;
  75
  76         found = NULL;
  77         for (c = table; *c != NULL; c = (char **)((char *)c + stlen)) {
  78                 if ((n = isprefix(name, *c)) == 0)
  79                         continue;
  80                 if (n < 0)              /* exact match */
  81                         return(c);
  82                 if (found)
  83                         return(&ambiguous);
  84                 found = c;
  85         }
  86         return(found);
  87 }
  88
  89 /*
  90  * Function call version of Ambiguous()
  91  */
  92 int
  93 Ambiguous(char **s)
  94 {
  95         return(s == &ambiguous);
  96 }