# mmap(2) blacklisting. Some platforms provide the mmap library routine # but don't support all of the features we need from it. AC_DEFUN(, [ AC_CHECK_HEADER(,

[libffi_header_sys_mman_h=yes], [libffi_header_sys_mman_h=no])

AC_CHECK_FUNC(, [libffi_func_mmap=yes], [libffi_func_mmap=no]) if test “$libffi_header_sys_mman_h” != yes \

|| test "$libffi_func_mmap" != yes; then
  ac_cv_func_mmap_file=no
  ac_cv_func_mmap_dev_zero=no
  ac_cv_func_mmap_anon=no

else

 AC_CACHE_CHECK([whether read-only mmap of a plain file works],
ac_cv_func_mmap_file,
[# Add a system to this blacklist if
 # mmap(0, stat_size, PROT_READ, MAP_PRIVATE, fd, 0) doesn't return a
 # memory area containing the same data that you'd get if you applied
 # read() to the same fd.  The only system known to have a problem here
 # is VMS, where text files have record structure.
 case "$host_os" in
   vms* | ultrix*)
      ac_cv_func_mmap_file=no ;;
   *)
      ac_cv_func_mmap_file=yes;;
 esac])
 AC_CACHE_CHECK([whether mmap from /dev/zero works],
ac_cv_func_mmap_dev_zero,
[# Add a system to this blacklist if it has mmap() but /dev/zero
 # does not exist, or if mmapping /dev/zero does not give anonymous
 # zeroed pages with both the following properties:
 # 1. If you map N consecutive pages in with one call, and then
 #    unmap any subset of those pages, the pages that were not
 #    explicitly unmapped remain accessible.
 # 2. If you map two adjacent blocks of memory and then unmap them
 #    both at once, they must both go away.
 # Systems known to be in this category are Windows (all variants),
 # VMS, and Darwin.
 case "$host_os" in
   vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00)
      ac_cv_func_mmap_dev_zero=no ;;
   *)
      ac_cv_func_mmap_dev_zero=yes;;
 esac])

 # Unlike /dev/zero, the MAP_ANON(YMOUS) defines can be probed for.
 AC_CACHE_CHECK([for MAP_ANON(YMOUS)], ac_cv_decl_map_anon,
  [AC_TRY_COMPILE(

[#include <sys/types.h> include <sys/mman.h> include <unistd.h>

ifndef MAP_ANONYMOUS define MAP_ANONYMOUS MAP_ANON endif ], [int n = MAP_ANONYMOUS;],

  ac_cv_decl_map_anon=yes,
  ac_cv_decl_map_anon=no)])

 if test $ac_cv_decl_map_anon = no; then
   ac_cv_func_mmap_anon=no
 else
   AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works],
   ac_cv_func_mmap_anon,
[# Add a system to this blacklist if it has mmap() and MAP_ANON or
 # MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
 # doesn't give anonymous zeroed pages with the same properties listed
 # above for use of /dev/zero.
 # Systems known to be in this category are Windows, VMS, and SCO Unix.
 case "$host_os" in
   vms* | cygwin* | pe | mingw* | sco* | udk* )
      ac_cv_func_mmap_anon=no ;;
   *)
      ac_cv_func_mmap_anon=yes;;
 esac])
 fi

fi

if test $ac_cv_func_mmap_file = yes; then

AC_DEFINE(HAVE_MMAP_FILE, 1,
          [Define if read-only mmap of a plain file works.])

fi if test $ac_cv_func_mmap_dev_zero = yes; then

AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1,
          [Define if mmap of /dev/zero works.])

fi if test $ac_cv_func_mmap_anon = yes; then

AC_DEFINE(HAVE_MMAP_ANON, 1,
          [Define if mmap with MAP_ANON(YMOUS) works.])

fi ])