xref: /freebsd/bin/sh/mystring.c (revision cc3f4b99653c34ae64f8a1fddea370abefef680e)
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  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)mystring.c	8.2 (Berkeley) 5/4/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 /*
42  * String functions.
43  *
44  *	equal(s1, s2)		Return true if strings are equal.
45  *	number(s)		Convert a string of digits to an integer.
46  *	is_number(s)		Return true if s is a string of digits.
47  */
48 
49 #include <stdlib.h>
50 #include "shell.h"
51 #include "syntax.h"
52 #include "error.h"
53 #include "mystring.h"
54 
55 
56 char nullstr[1];		/* zero length string */
57 
58 /*
59  * equal - #defined in mystring.h
60  */
61 
62 
63 /*
64  * prefix -- see if pfx is a prefix of string.
65  */
66 
67 int
68 prefix(const char *pfx, const char *string)
69 {
70 	while (*pfx) {
71 		if (*pfx++ != *string++)
72 			return 0;
73 	}
74 	return 1;
75 }
76 
77 
78 /*
79  * Convert a string of digits to an integer, printing an error message on
80  * failure.
81  */
82 
83 int
84 number(const char *s)
85 {
86 	if (! is_number(s))
87 		error("Illegal number: %s", s);
88 	return atoi(s);
89 }
90 
91 
92 
93 /*
94  * Check for a valid number.  This should be elsewhere.
95  */
96 
97 int
98 is_number(const char *p)
99 {
100 	do {
101 		if (! is_digit(*p))
102 			return 0;
103 	} while (*++p != '\0');
104 	return 1;
105 }
106