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mystring.c revision 1.7 
      1 /*-
      2  * Copyright (c) 1991, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Kenneth Almquist.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #ifndef lint
     38 static char sccsid[] = "@(#)mystring.c	8.1 (Berkeley) 5/31/93";
     39 #endif /* not lint */
     40 
     41 /*
     42  * String functions.
     43  *
     44  *	equal(s1, s2)		Return true if strings are equal.
     45  *	scopy(from, to)		Copy a string.
     46  *	scopyn(from, to, n)	Like scopy, but checks for overflow.
     47  *	number(s)		Convert a string of digits to an integer.
     48  *	is_number(s)		Return true if s is a string of digits.
     49  */
     50 
     51 #include <stdlib.h>
     52 #include "shell.h"
     53 #include "syntax.h"
     54 #include "error.h"
     55 #include "mystring.h"
     56 
     57 
     58 char nullstr[1];		/* zero length string */
     59 
     60 /*
     61  * equal - #defined in mystring.h
     62  */
     63 
     64 /*
     65  * scopy - #defined in mystring.h
     66  */
     67 
     68 
     69 /*
     70  * scopyn - copy a string from "from" to "to", truncating the string
     71  *		if necessary.  "To" is always nul terminated, even if
     72  *		truncation is performed.  "Size" is the size of "to".
     73  */
     74 
     75 void
     76 scopyn(from, to, size)
     77 	register char const *from;
     78 	register char *to;
     79 	register int size;
     80 	{
     81 
     82 	while (--size > 0) {
     83 		if ((*to++ = *from++) == '\0')
     84 			return;
     85 	}
     86 	*to = '\0';
     87 }
     88 
     89 
     90 /*
     91  * prefix -- see if pfx is a prefix of string.
     92  */
     93 
     94 int
     95 prefix(pfx, string)
     96 	register char const *pfx;
     97 	register char const *string;
     98 	{
     99 	while (*pfx) {
    100 		if (*pfx++ != *string++)
    101 			return 0;
    102 	}
    103 	return 1;
    104 }
    105 
    106 
    107 /*
    108  * Convert a string of digits to an integer, printing an error message on
    109  * failure.
    110  */
    111 
    112 int
    113 number(s)
    114 	const char *s;
    115 	{
    116 
    117 	if (! is_number(s))
    118 		error2("Illegal number", (char *)s);
    119 	return atoi(s);
    120 }
    121 
    122 
    123 
    124 /*
    125  * Check for a valid number.  This should be elsewhere.
    126  */
    127 
    128 int
    129 is_number(p)
    130 	register const char *p;
    131 	{
    132 	do {
    133 		if (! is_digit(*p))
    134 			return 0;
    135 	} while (*++p != '\0');
    136 	return 1;
    137 }
    138