xref: /illumos-gate/usr/src/lib/libc/port/gen/gethz.c (revision ddb365bfc9e868ad24ccdcb0dc91af18b10df082)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #pragma weak _gethz = gethz
31 
32 #include "lint.h"
33 #include <stdio.h>
34 #include <ctype.h>
35 #include <stdlib.h>
36 
37 /*
38  *	gethz -- get the value of the clock hertz from the environment.
39  *
40  *	return the clock hertz value if the string "HZ" in the environment is:
41  *		1) Composed entirely of numbers.
42  *		2) Not equal to zero.
43  *	Otherwise 0 is returned.
44  */
45 int
46 gethz(void)
47 {
48 	char *sptr, *cptr;
49 
50 	if ((sptr = getenv("HZ")) == NULL) {
51 		return (0);
52 	} else {
53 		cptr = sptr;
54 
55 		/* Check that all characters are numeric */
56 		while (*cptr) {
57 			if (!isdigit((unsigned char)*cptr))
58 				return (0);
59 			cptr++;
60 		}
61 		return (atoi(sptr));
62 	}
63 }
64