libs-base/config/procfs.m4

dnl AC_SYS_PROCFS
dnl This macro defines HAVE_PROCFS if either it finds a mounted /proc
dnl or the user explicitly enables it for cross-compiles.
dnl  Copyright (C) 2005 Free Software Foundation
dnl  Copying and distribution of this file, with or without modification,
dnl  are permitted in any medium without royalty provided the copyright
dnl  notice and this notice are preserved.
AC_DEFUN(AC_SYS_PROCFS,
[ AC_ARG_ENABLE(procfs,
    [  --enable-procfs               Use /proc filesystem (default)],
    enable_procfs="$enableval", if test "$cross_compiling" = yes; then enable_procfs=cross; else enable_procfs=yes; fi;)

  AC_CACHE_CHECK([kernel support for /proc filesystem], ac_cv_sys_procfs,
  [if test "$enable_procfs" = yes; then
  # Suggested change for the following line was 
  #  if test -d /proc/0; then
  # but it doesn't work on my linux - /proc/0 does not exist, but /proc
  # works fine
    if (mount | grep 'proc' >/dev/null 2>/dev/null); then 
      ac_cv_sys_procfs=yes
    else
      ac_cv_sys_procfs=no
    fi
    case "$target_os" in
      # Solaris has proc, but it is not readable
      solaris*)    ac_cv_sys_procfs=no;;
      irix*)       ac_cv_sys_procfs=no;;
      # Cygwin does have proc, but it does not show with mount
      cygwin*)     ac_cv_sys_procfs=yes;;
    esac
  elif test "$enable_procfs" = cross; then
    AC_MSG_WARN(Pass --enable-procfs argument to enable use of /proc filesystem.)
  else
    ac_cv_sys_procfs=no
  fi])

  if test $ac_cv_sys_procfs = yes; then
    AC_DEFINE(HAVE_PROCFS, 1, [Define if system supports the /proc filesystem])
  fi
]
)