[unix-history] / usr / src / lib / libtelnet / genget.c

/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char sccsid[] = "@(#)genget.c    5.1 (Berkeley) %G%";
#endif /* not lint */


#include <ctype.h>

#define LOWER(x) (isupper(x) ? tolower(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(s1, s2)
       register char *s1, *s2;
{
       register int n = 0;
       char *os1;
       register 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(name, table, stlen)
       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(s)
       char *s;
{
       return((char **)s == &ambiguous);
}