sysdeps/unix/sysv/linux/getsysstats.c

   1 /* Determine various system internal values, Linux version.
   2    Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <alloca.h>
  22 #include <errno.h>
  23 #include <mntent.h>
  24 #include <paths.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <sys/sysinfo.h>
  29
  30
  31 /* Determine the path to the /proc filesystem if available.  */
  32 static char *
  33 internal_function
  34 get_proc_path (char *buffer, size_t bufsize)
  35 {
  36   FILE *fp;
  37   struct mntent mount_point;
  38   struct mntent *entry;
  39   char *result = NULL;
  40
  41   /* First find the mount point of the proc filesystem.  */
  42   fp = __setmntent (_PATH_MNTTAB, "r");
  43   if (fp != NULL)
  44     {
  45       while ((entry = __getmntent_r (fp, &mount_point, buffer, bufsize))
  46              != NULL)
  47         if (strcmp (mount_point.mnt_type, "proc") == 0)
  48           {
  49             result = mount_point.mnt_dir;
  50             break;
  51           }
  52       __endmntent (fp);
  53     }
  54
  55   return result;
  56 }
  57
  58
  59 /* How we can determine the number of available processors depends on
  60    the configuration.  There is currently (as of version 2.0.21) no
  61    system call to determine the number.  It is planned for the 2.1.x
  62    series to add this, though.
  63
  64    One possibility to implement it for systems using Linux 2.0 is to
  65    examine the pseudo file /proc/meminfo.  Here we have one entry for
  66    each processor.
  67
  68    But not all systems have support for the /proc filesystem.  If it
  69    is not available we simply return 1 since there is no way.  */
  70 int
  71 __get_nprocs ()
  72 {
  73   FILE *fp;
  74   char buffer[8192];
  75   char *proc_path;
  76   int result = 1;
  77
  78   /* XXX Here will come a test for the new system call.  */
  79
  80   /* Get mount point of proc filesystem.  */
  81   proc_path = get_proc_path (buffer, sizeof buffer);
  82
  83   /* If we haven't found an appropriate entry return 1.  */
  84   if (proc_path != NULL)
  85     {
  86       char *proc_cpuinfo = alloca (strlen (proc_path) + sizeof ("/cpuinfo"));
  87       __stpcpy (__stpcpy (proc_cpuinfo, proc_path), "/cpuinfo");
  88
  89       fp = fopen (proc_cpuinfo, "r");
  90       if (fp != NULL)
  91         {
  92           result = 0;
  93           /* Read all lines and count the lines starting with the
  94              string "processor".  We don't have to fear extremely long
  95              lines since the kernel will not generate them.  8192
  96              bytes are really enough.  */
  97           while (fgets (buffer, sizeof buffer, fp) != NULL)
  98             if (strncmp (buffer, "processor", 9) == 0)
  99               ++result;
 100
 101           fclose (fp);
 102         }
 103     }
 104
 105   return result;
 106 }
 107 weak_alias (__get_nprocs, get_nprocs)
 108
 109 /* As far as I know Linux has no separate numbers for configured and
 110    available processors.  So make the `get_nprocs_conf' function an
 111    alias.  */
 112 strong_alias (__get_nprocs, __get_nprocs_conf)
 113 weak_alias (__get_nprocs, get_nprocs_conf)
 114
 115
 116 /* General function to get information about memory status from proc
 117    filesystem.  */
 118 static int
 119 internal_function
 120 phys_pages_info (const char *format)
 121 {
 122   FILE *fp;
 123   char buffer[8192];
 124   char *proc_path;
 125   int result = -1;
 126
 127   /* Get mount point of proc filesystem.  */
 128   proc_path = get_proc_path (buffer, sizeof buffer);
 129
 130   /* If we haven't found an appropriate entry return 1.  */
 131   if (proc_path != NULL)
 132     {
 133       char *proc_meminfo = alloca (strlen (proc_path) + sizeof ("/meminfo"));
 134       __stpcpy (__stpcpy (proc_meminfo, proc_path), "/meminfo");
 135
 136       fp = fopen (proc_meminfo, "r");
 137       if (fp != NULL)
 138         {
 139           result = 0;
 140           /* Read all lines and count the lines starting with the
 141              string "processor".  We don't have to fear extremely long
 142              lines since the kernel will not generate them.  8192
 143              bytes are really enough.  */
 144           while (fgets (buffer, sizeof buffer, fp) != NULL)
 145             if (sscanf (buffer, format, &result) == 1)
 146               {
 147                 result /= (__getpagesize () / 1024);
 148                 break;
 149               }
 150
 151           fclose (fp);
 152         }
 153     }
 154
 155   if (result == -1)
 156     /* We cannot get the needed value: signal an error.  */
 157     __set_errno (ENOSYS);
 158
 159   return result;
 160 }
 161
 162
 163 /* Return the number of pages of physical memory in the system.  There
 164    is currently (as of version 2.0.21) no system call to determine the
 165    number.  It is planned for the 2.1.x series to add this, though.
 166
 167    One possibility to implement it for systems using Linux 2.0 is to
 168    examine the pseudo file /proc/cpuinfo.  Here we have one entry for
 169    each processor.
 170
 171    But not all systems have support for the /proc filesystem.  If it
 172    is not available we return -1 as an error signal.  */
 173 int
 174 __get_phys_pages ()
 175 {
 176   /* XXX Here will come a test for the new system call.  */
 177
 178   return phys_pages_info ("MemTotal: %d kB");
 179 }
 180 weak_alias (__get_phys_pages, get_phys_pages)
 181
 182
 183 /* Return the number of available pages of physical memory in the
 184    system.  There is currently (as of version 2.0.21) no system call
 185    to determine the number.  It is planned for the 2.1.x series to add
 186    this, though.
 187
 188    One possibility to implement it for systems using Linux 2.0 is to
 189    examine the pseudo file /proc/cpuinfo.  Here we have one entry for
 190    each processor.
 191
 192    But not all systems have support for the /proc filesystem.  If it
 193    is not available we return -1 as an error signal.  */
 194 int
 195 __get_avphys_pages ()
 196 {
 197   /* XXX Here will come a test for the new system call.  */
 198
 199   return phys_pages_info ("MemFree: %d kB");
 200 }
 201 weak_alias (__get_avphys_pages, get_avphys_pages)