glibc/sysdeps/unix/sysv/linux/getsysstats.c

/* getsysstats - Determine various system internal values, Linux version.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <mntent.h>
#include <paths.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/sysinfo.h>


/* Determine the path to the /proc filesystem if available.  */
static char *
get_proc_path (char *buffer, size_t bufsize)
{
  FILE *fp;
  struct mntent mount_point;
  struct mntent *entry;
  char *result = NULL;

  /* First find the mount point of the proc filesystem.  */
  fp = __setmntent (_PATH_MNTTAB, "r");
  if (fp != NULL)
    {
      while ((entry = __getmntent_r (fp, &mount_point, buffer, bufsize))
	     != NULL)
	if (strcmp (mount_point.mnt_type, "proc") == 0)
	  {
	    result = mount_point.mnt_dir;
	    break;
	  }
      __endmntent (fp);
    }

  return result;
}


/* How we can determine the number of available processors depends on
   the configuration.  There is currently (as of version 2.0.21) no
   system call to determine the number.  It is planned for the 2.1.x
   series to add this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/meminfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we simply return 1 since there is no way.  */
int
__get_nprocs ()
{
  FILE *fp;
  char buffer[8192];
  char *proc_path;
  int result = 1;

  /* XXX Here will come a test for the new system call.  */

  /* Get mount point of proc filesystem.  */
  proc_path = get_proc_path (buffer, sizeof buffer);

  /* If we haven't found an appropriate entry return 1.  */
  if (proc_path != NULL)
    {
      char *proc_cpuinfo = alloca (strlen (proc_path) + sizeof ("/cpuinfo"));
      __stpcpy (__stpcpy (proc_cpuinfo, proc_path), "/cpuinfo");

      fp = fopen (proc_cpuinfo, "r");
      if (fp != NULL)
	{
	  result = 0;
	  /* Read all lines and count the lines starting with the
	     string "processor".  We don't have to fear extremely long
	     lines since the kernel will not generate them.  8192
	     bytes are really enough.  */
	  while (fgets (buffer, sizeof buffer, fp) != NULL)
	    if (strncmp (buffer, "processor", 9) == 0)
	      ++result;

	  fclose (fp);
	}
    }

  return result;
}
weak_alias (__get_nprocs, get_nprocs)

/* As far as I know Linux has no separate numbers for configured and
   available processors.  So make the `get_nprocs_conf' function an
   alias.  */
strong_alias (__get_nprocs, __get_nprocs_conf)
weak_alias (__get_nprocs, get_nprocs_conf)


/* General function to get information about memory status from proc
   filesystem.  */
static int
phys_pages_info (const char *format)
{
  FILE *fp;
  char buffer[8192];
  char *proc_path;
  int result = -1;

  /* Get mount point of proc filesystem.  */
  proc_path = get_proc_path (buffer, sizeof buffer);

  /* If we haven't found an appropriate entry return 1.  */
  if (proc_path != NULL)
    {
      char *proc_meminfo = alloca (strlen (proc_path) + sizeof ("/meminfo"));
      __stpcpy (__stpcpy (proc_meminfo, proc_path), "/meminfo");

      fp = fopen (proc_meminfo, "r");
      if (fp != NULL)
	{
	  result = 0;
	  /* Read all lines and count the lines starting with the
	     string "processor".  We don't have to fear extremely long
	     lines since the kernel will not generate them.  8192
	     bytes are really enough.  */
	  while (fgets (buffer, sizeof buffer, fp) != NULL)
	    if (sscanf (buffer, format, &result) == 1)
	      {
		result /= (__getpagesize () / 1024);
		break;
	      }

	  fclose (fp);
	}
    }

  if (result == -1)
    /* We cannot get the needed value: signal an error.  */
    __set_errno (ENOSYS);

  return result;
}


/* Return the number of pages of physical memory in the system.  There
   is currently (as of version 2.0.21) no system call to determine the
   number.  It is planned for the 2.1.x series to add this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/cpuinfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we return -1 as an error signal.  */
int
__get_phys_pages ()
{
  /* XXX Here will come a test for the new system call.  */

  return phys_pages_info ("MemTotal: %d kB");
}
weak_alias (__get_phys_pages, get_phys_pages)


/* Return the number of available pages of physical memory in the
   system.  There is currently (as of version 2.0.21) no system call
   to determine the number.  It is planned for the 2.1.x series to add
   this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/cpuinfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we return -1 as an error signal.  */
int
__get_avphys_pages ()
{
  /* XXX Here will come a test for the new system call.  */

  return phys_pages_info ("MemFree: %d kB");
}
weak_alias (__get_avphys_pages, get_avphys_pages)