projects/sample/autoconf/m4/need_dev_zero_for_mmap.m4

   1 #
   2 # When allocating RWX memory, check whether we need to use /dev/zero
   3 # as the file descriptor or not.
   4 #
   5 AC_DEFUN([AC_NEED_DEV_ZERO_FOR_MMAP],
   6 [AC_CACHE_CHECK([if /dev/zero is needed for mmap],
   7 ac_cv_need_dev_zero_for_mmap,
   8 [if test "$llvm_cv_os_type" = "Interix" ; then
   9    ac_cv_need_dev_zero_for_mmap=yes
  10  else
  11    ac_cv_need_dev_zero_for_mmap=no
  12  fi
  13 ])
  14 if test "$ac_cv_need_dev_zero_for_mmap" = yes; then
  15   AC_DEFINE([NEED_DEV_ZERO_FOR_MMAP],[1],
  16    [Define if /dev/zero should be used when mapping RWX memory, or undefine if its not necessary])
  17 fi])