sysdeps/unix/sysv/linux/getsysstats.c

   1 /* getsysstats - Determine various system internal values, Linux version.
   2    Copyright (C) 1996 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 get_proc_path (char *buffer, size_t bufsize)
  34 {
  35   FILE *fp;
  36   struct mntent mount_point;
  37   struct mntent *entry;
  38   char *result = NULL;
  39
  40   /* First find the mount point of the proc filesystem.  */
  41   fp = __setmntent (_PATH_MNTTAB, "r");
  42   if (fp != NULL)
  43     {
  44       while ((entry = __getmntent_r (fp, &mount_point, buffer, bufsize))
  45              != NULL)
  46         if (strcmp (mount_point.mnt_type, "proc") == 0)
  47           {
  48             result = mount_point.mnt_dir;
  49             break;
  50           }
  51       __endmntent (fp);
  52     }
  53
  54   return result;
  55 }
  56
  57
  58 /* How we can determine the number of available processors depends on
  59    the configuration.  There is currently (as of version 2.0.21) no
  60    system call to determine the number.  It is planned for the 2.1.x
  61    series to add this, though.
  62
  63    One possibility to implement it for systems using Linux 2.0 is to
  64    examine the pseudo file /proc/meminfo.  Here we have one entry for
  65    each processor.
  66
  67    But not all systems have support for the /proc filesystem.  If it
  68    is not available we simply return 1 since there is no way.  */
  69 int
  70 __get_nprocs ()
  71 {
  72   FILE *fp;
  73   char buffer[8192];
  74   char *proc_path;
  75   int result = 1;
  76
  77   /* XXX Here will come a test for the new system call.  */
  78
  79   /* Get mount point of proc filesystem.  */
  80   proc_path = get_proc_path (buffer, sizeof buffer);
  81
  82   /* If we haven't found an appropriate entry return 1.  */
  83   if (proc_path != NULL)
  84     {
  85       char *proc_cpuinfo = alloca (strlen (proc_path) + sizeof ("/cpuinfo"));
  86       __stpcpy (__stpcpy (proc_cpuinfo, proc_path), "/cpuinfo");
  87
  88       fp = fopen (proc_cpuinfo, "r");
  89       if (fp != NULL)
  90         {
  91           result = 0;
  92           /* Read all lines and count the lines starting with the
  93              string "processor".  We don't have to fear extremely long
  94              lines since the kernel will not generate them.  8192
  95              bytes are really enough.  */
  96           while (fgets (buffer, sizeof buffer, fp) != NULL)
  97             if (strncmp (buffer, "processor", 9) == 0)
  98               ++result;
  99
 100           fclose (fp);
 101         }
 102     }
 103
 104   return result;
 105 }
 106 weak_alias (__get_nprocs, get_nprocs)
 107
 108 /* As far as I know Linux has no separate numbers for configured and
 109    available processors.  So make the `get_nprocs_conf' function an
 110    alias.  */
 111 strong_alias (__get_nprocs, __get_nprocs_conf)
 112 weak_alias (__get_nprocs, get_nprocs_conf)
 113
 114
 115 /* General function to get information about memory status from proc
 116    filesystem.  */
 117 static int
 118 phys_pages_info (const char *format)
 119 {
 120   FILE *fp;
 121   char buffer[8192];
 122   char *proc_path;
 123   int result = -1;
 124
 125   /* Get mount point of proc filesystem.  */
 126   proc_path = get_proc_path (buffer, sizeof buffer);
 127
 128   /* If we haven't found an appropriate entry return 1.  */
 129   if (proc_path != NULL)
 130     {
 131       char *proc_meminfo = alloca (strlen (proc_path) + sizeof ("/meminfo"));
 132       __stpcpy (__stpcpy (proc_meminfo, proc_path), "/meminfo");
 133
 134       fp = fopen (proc_meminfo, "r");
 135       if (fp != NULL)
 136         {
 137           result = 0;
 138           /* Read all lines and count the lines starting with the
 139              string "processor".  We don't have to fear extremely long
 140              lines since the kernel will not generate them.  8192
 141              bytes are really enough.  */
 142           while (fgets (buffer, sizeof buffer, fp) != NULL)
 143             if (sscanf (buffer, format, &result) == 1)
 144               {
 145                 result /= (__getpagesize () / 1024);
 146                 break;
 147               }
 148
 149           fclose (fp);
 150         }
 151     }
 152
 153   if (result == -1)
 154     /* We cannot get the needed value: signal an error.  */
 155     __set_errno (ENOSYS);
 156
 157   return result;
 158 }
 159
 160
 161 /* Return the number of pages of physical memory in the system.  There
 162    is currently (as of version 2.0.21) no system call to determine the
 163    number.  It is planned for the 2.1.x series to add this, though.
 164
 165    One possibility to implement it for systems using Linux 2.0 is to
 166    examine the pseudo file /proc/cpuinfo.  Here we have one entry for
 167    each processor.
 168
 169    But not all systems have support for the /proc filesystem.  If it
 170    is not available we return -1 as an error signal.  */
 171 int
 172 __get_phys_pages ()
 173 {
 174   /* XXX Here will come a test for the new system call.  */
 175
 176   return phys_pages_info ("MemTotal: %d kB");
 177 }
 178 weak_alias (__get_phys_pages, get_phys_pages)
 179
 180
 181 /* Return the number of available pages of physical memory in the
 182    system.  There is currently (as of version 2.0.21) no system call
 183    to determine the number.  It is planned for the 2.1.x series to add
 184    this, though.
 185
 186    One possibility to implement it for systems using Linux 2.0 is to
 187    examine the pseudo file /proc/cpuinfo.  Here we have one entry for
 188    each processor.
 189
 190    But not all systems have support for the /proc filesystem.  If it
 191    is not available we return -1 as an error signal.  */
 192 int
 193 __get_avphys_pages ()
 194 {
 195   /* XXX Here will come a test for the new system call.  */
 196
 197   return phys_pages_info ("MemFree: %d kB");
 198 }
 199 weak_alias (__get_avphys_pages, get_avphys_pages)