1dnl ----------------------------------------------------------------------
2dnl This whole bit snagged from gcc
3
4dnl
5dnl mmap(2) blacklisting.  Some platforms provide the mmap library routine
6dnl but don't support all of the features we need from it.
7dnl
8AC_DEFUN([GCC_AC_FUNC_MMAP_BLACKLIST],
9[
10AC_CHECK_HEADER([sys/mman.h],
11		[gcc_header_sys_mman_h=yes], [gcc_header_sys_mman_h=no])
12AC_CHECK_FUNC([mmap], [gcc_func_mmap=yes], [gcc_func_mmap=no])
13if test "$gcc_header_sys_mman_h" != yes \
14 || test "$gcc_func_mmap" != yes; then
15   gcc_cv_func_mmap_file=no
16   gcc_cv_func_mmap_dev_zero=no
17   gcc_cv_func_mmap_anon=no
18else
19   AC_CACHE_CHECK([whether read-only mmap of a plain file works],
20  gcc_cv_func_mmap_file,
21  [# Add a system to this blacklist if
22   # mmap(0, stat_size, PROT_READ, MAP_PRIVATE, fd, 0) doesn't return a
23   # memory area containing the same data that you'd get if you applied
24   # read() to the same fd.  The only system known to have a problem here
25   # is VMS, where text files have record structure.
26   case "$host_os" in
27     *vms* | ultrix*)
28        gcc_cv_func_mmap_file=no ;;
29     *)
30        gcc_cv_func_mmap_file=yes;;
31   esac])
32   AC_CACHE_CHECK([whether mmap from /dev/zero works],
33  gcc_cv_func_mmap_dev_zero,
34  [# Add a system to this blacklist if it has mmap() but /dev/zero
35   # does not exist, or if mmapping /dev/zero does not give anonymous
36   # zeroed pages with both the following properties:
37   # 1. If you map N consecutive pages in with one call, and then
38   #    unmap any subset of those pages, the pages that were not
39   #    explicitly unmapped remain accessible.
40   # 2. If you map two adjacent blocks of memory and then unmap them
41   #    both at once, they must both go away.
42   # Systems known to be in this category are Windows (all variants),
43   # VMS, and Darwin.
44   case "$host_os" in
45     *vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00)
46        gcc_cv_func_mmap_dev_zero=no ;;
47     *)
48        gcc_cv_func_mmap_dev_zero=yes;;
49   esac])
50
51   # Unlike /dev/zero, the MAP_ANON(YMOUS) defines can be probed for.
52   AC_CACHE_CHECK([for MAP_ANON(YMOUS)], gcc_cv_decl_map_anon,
53    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
54[#include <sys/types.h>
55#include <sys/mman.h>
56#include <unistd.h>
57
58#ifndef MAP_ANONYMOUS
59#define MAP_ANONYMOUS MAP_ANON
60#endif
61],
62[int n = MAP_ANONYMOUS;])],
63    gcc_cv_decl_map_anon=yes,
64    gcc_cv_decl_map_anon=no)])
65
66   if test $gcc_cv_decl_map_anon = no; then
67     gcc_cv_func_mmap_anon=no
68   else
69     AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works],
70     gcc_cv_func_mmap_anon,
71  [# Add a system to this blacklist if it has mmap() and MAP_ANON or
72   # MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
73   # doesn't give anonymous zeroed pages with the same properties listed
74   # above for use of /dev/zero.
75   # Systems known to be in this category are Windows, VMS, and SCO Unix.
76   case "$host_os" in
77     *vms* | cygwin* | pe | mingw* | sco* | udk* )
78        gcc_cv_func_mmap_anon=no ;;
79     *)
80        gcc_cv_func_mmap_anon=yes;;
81   esac])
82   fi
83fi
84
85if test $gcc_cv_func_mmap_file = yes; then
86  AC_DEFINE(HAVE_MMAP_FILE, 1,
87	    [Define if read-only mmap of a plain file works.])
88fi
89if test $gcc_cv_func_mmap_dev_zero = yes; then
90  AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1,
91	    [Define if mmap of /dev/zero works.])
92fi
93if test $gcc_cv_func_mmap_anon = yes; then
94  AC_DEFINE(HAVE_MMAP_ANON, 1,
95	    [Define if mmap with MAP_ANON(YMOUS) works.])
96fi
97])
98