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glibc  2.9
getloadavg.c
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00001 /* Get system load averages.  Linux (/proc/loadavg) version.
00002    Copyright (C) 1999, 2000, 2001, 2003, 2005 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include <fcntl.h>
00022 #include <locale.h>
00023 #include <stdlib.h>
00024 #include <unistd.h>
00025 #include <not-cancel.h>
00026 
00027 /* Put the 1 minute, 5 minute and 15 minute load averages
00028    into the first NELEM elements of LOADAVG.
00029    Return the number written (never more than 3, but may be less than NELEM),
00030    or -1 if an error occurred.  */
00031 
00032 int
00033 getloadavg (double loadavg[], int nelem)
00034 {
00035   int fd;
00036 
00037   fd = open_not_cancel_2 ("/proc/loadavg", O_RDONLY);
00038   if (fd < 0)
00039     return -1;
00040   else
00041     {
00042       char buf[65], *p;
00043       ssize_t nread;
00044       int i;
00045 
00046       nread = read_not_cancel (fd, buf, sizeof buf - 1);
00047       close_not_cancel_no_status (fd);
00048       if (nread <= 0)
00049        return -1;
00050       buf[nread - 1] = '\0';
00051 
00052       if (nelem > 3)
00053        nelem = 3;
00054       p = buf;
00055       for (i = 0; i < nelem; ++i)
00056        {
00057          char *endp;
00058          loadavg[i] = __strtod_l (p, &endp, _nl_C_locobj_ptr);
00059          if (endp == p)
00060            /* This should not happen.  The format of /proc/loadavg
00061               must have changed.  Don't return with what we have,
00062               signal an error.  */
00063            return -1;
00064          p = endp;
00065        }
00066 
00067       return i;
00068     }
00069 }