usr/src/lib/libc/port/gen/gethz.c

   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 ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #pragma weak _gethz = gethz
  33
  34 #include "lint.h"
  35 #include <stdio.h>
  36 #include <ctype.h>
  37 #include <stdlib.h>
  38
  39 /*
  40  *      gethz -- get the value of the clock hertz from the environment.
  41  *
  42  *      return the clock hertz value if the string "HZ" in the environment is:
  43  *              1) Composed entirely of numbers.
  44  *              2) Not equal to zero.
  45  *      Otherwise 0 is returned.
  46  */
  47 int
  48 gethz(void)
  49 {
  50         char *sptr, *cptr;
  51
  52         if ((sptr = getenv("HZ")) == NULL) {
  53                 return (0);
  54         } else {
  55                 cptr = sptr;
  56
  57                 /* Check that all characters are numeric */
  58                 while (*cptr) {
  59                         if (!isdigit((unsigned char)*cptr))
  60                                 return (0);
  61                         cptr++;
  62                 }
  63                 return (atoi(sptr));
  64         }
  65 }