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mystring.c revision 1.5 
      1 /*-
      2  * Copyright (c) 1991 The Regents of the University of California.
      3  * 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[] = "from: @(#)mystring.c	5.1 (Berkeley) 3/7/91";*/
     39 static char rcsid[] = "$Id: mystring.c,v 1.5 1994/05/04 23:46:28 jtc Exp $";
     40 #endif /* not lint */
     41 
     42 /*
     43  * String functions.
     44  *
     45  *	equal(s1, s2)		Return true if strings are equal.
     46  *	scopy(from, to)		Copy a string.
     47  *	scopyn(from, to, n)	Like scopy, but checks for overflow.
     48  *	number(s)		Convert a string of digits to an integer.
     49  *	is_number(s)		Return true if s is a string of digits.
     50  */
     51 
     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 /*
     62  * scopyn - copy a string from "from" to "to", truncating the string
     63  *		if necessary.  "To" is always nul terminated, even if
     64  *		truncation is performed.  "Size" is the size of "to".
     65  */
     66 
     67 void
     68 scopyn(from, to, size)
     69 	register char const *from;
     70 	register char *to;
     71 	register int size;
     72 	{
     73 
     74 	while (--size > 0) {
     75 		if ((*to++ = *from++) == '\0')
     76 			return;
     77 	}
     78 	*to = '\0';
     79 }
     80 
     81 
     82 /*
     83  * prefix -- see if pfx is a prefix of string.
     84  */
     85 
     86 int
     87 prefix(pfx, string)
     88 	register char const *pfx;
     89 	register char const *string;
     90 	{
     91 	while (*pfx) {
     92 		if (*pfx++ != *string++)
     93 			return 0;
     94 	}
     95 	return 1;
     96 }
     97 
     98 
     99 /*
    100  * Convert a string of digits to an integer, printing an error message on
    101  * failure.
    102  */
    103 
    104 int
    105 number(s)
    106 	const char *s;
    107 	{
    108 
    109 	if (! is_number(s))
    110 		error2("Illegal number", (char *)s);
    111 	return atoi(s);
    112 }
    113 
    114 
    115 
    116 /*
    117  * Check for a valid number.  This should be elsewhere.
    118  */
    119 
    120 int
    121 is_number(p)
    122 	register const char *p;
    123 	{
    124 	do {
    125 		if (! is_digit(*p))
    126 			return 0;
    127 	} while (*++p != '\0');
    128 	return 1;
    129 }
    130