xref: /illumos-gate/usr/src/lib/libc/port/gen/gethz.c (revision 3db86aab)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 /*	Copyright (c) 1988 AT&T	*/
30 /*	  All Rights Reserved  	*/
31 
32 
33 #pragma weak gethz = _gethz
34 
35 #include "synonyms.h"
36 #include <stdio.h>
37 #include <ctype.h>
38 #include <stdlib.h>
39 
40 /*
41  *	gethz -- get the value of the clock hertz from the environment.
42  *
43  *	return the clock hertz value if the string "HZ" in the environment is:
44  *		1) Composed entirely of numbers.
45  *		2) Not equal to zero.
46  *	Otherwise 0 is returned.
47  */
48 int
49 gethz(void)
50 {
51 	char *sptr, *cptr;
52 
53 	if ((sptr = getenv("HZ")) == NULL) {
54 		return (0);
55 	} else {
56 		cptr = sptr;
57 
58 		/* Check that all characters are numeric */
59 		while (*cptr) {
60 			if (!isdigit((unsigned char)*cptr))
61 				return (0);
62 			cptr++;
63 		}
64 		return (atoi(sptr));
65 	}
66 }
67