sysdeps/unix/sysv/linux/getloadavg.c

   1 /* Get system load averages.  Linux (/proc/loadavg) version.
   2    Copyright (C) 1999, 2000, 2001, 2003, 2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <locale.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <not-cancel.h>
  26
  27 /* Put the 1 minute, 5 minute and 15 minute load averages
  28    into the first NELEM elements of LOADAVG.
  29    Return the number written (never more than 3, but may be less than NELEM),
  30    or -1 if an error occurred.  */
  31
  32 int
  33 getloadavg (double loadavg[], int nelem)
  34 {
  35   int fd;
  36
  37   fd = open_not_cancel_2 ("/proc/loadavg", O_RDONLY);
  38   if (fd < 0)
  39     return -1;
  40   else
  41     {
  42       char buf[65], *p;
  43       ssize_t nread;
  44       int i;
  45
  46       nread = read_not_cancel (fd, buf, sizeof buf - 1);
  47       close_not_cancel_no_status (fd);
  48       if (nread <= 0)
  49         return -1;
  50       buf[nread - 1] = '\0';
  51
  52       if (nelem > 3)
  53         nelem = 3;
  54       p = buf;
  55       for (i = 0; i < nelem; ++i)
  56         {
  57           char *endp;
  58           loadavg[i] = __strtod_l (p, &endp, _nl_C_locobj_ptr);
  59           if (endp == p)
  60             /* This should not happen.  The format of /proc/loadavg
  61                must have changed.  Don't return with what we have,
  62                signal an error.  */
  63             return -1;
  64           p = endp;
  65         }
  66
  67       return i;
  68     }
  69 }