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mystring.c revision 1.6 
      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 "shell.h"
     52 #include "syntax.h"
     53 #include "error.h"
     54 #include "mystring.h"
     55 
     56 
     57 char nullstr[1];		/* zero length string */
     58 
     59 /*
     60  * equal - #defined in mystring.h
     61  */
     62 
     63 /*
     64  * scopy - #defined in mystring.h
     65  */
     66 
     67 
     68 /*
     69  * scopyn - copy a string from "from" to "to", truncating the string
     70  *		if necessary.  "To" is always nul terminated, even if
     71  *		truncation is performed.  "Size" is the size of "to".
     72  */
     73 
     74 void
     75 scopyn(from, to, size)
     76 	register char const *from;
     77 	register char *to;
     78 	register int size;
     79 	{
     80 
     81 	while (--size > 0) {
     82 		if ((*to++ = *from++) == '\0')
     83 			return;
     84 	}
     85 	*to = '\0';
     86 }
     87 
     88 
     89 /*
     90  * prefix -- see if pfx is a prefix of string.
     91  */
     92 
     93 int
     94 prefix(pfx, string)
     95 	register char const *pfx;
     96 	register char const *string;
     97 	{
     98 	while (*pfx) {
     99 		if (*pfx++ != *string++)
    100 			return 0;
    101 	}
    102 	return 1;
    103 }
    104 
    105 
    106 /*
    107  * Convert a string of digits to an integer, printing an error message on
    108  * failure.
    109  */
    110 
    111 int
    112 number(s)
    113 	const char *s;
    114 	{
    115 
    116 	if (! is_number(s))
    117 		error2("Illegal number", (char *)s);
    118 	return atoi(s);
    119 }
    120 
    121 
    122 
    123 /*
    124  * Check for a valid number.  This should be elsewhere.
    125  */
    126 
    127 int
    128 is_number(p)
    129 	register const char *p;
    130 	{
    131 	do {
    132 		if (! is_digit(*p))
    133 			return 0;
    134 	} while (*++p != '\0');
    135 	return 1;
    136 }
    137