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/Modules/_ctypes/libffi/acinclude.m4

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m4 | 92 lines | 63 code | 4 blank | 25 comment | 0 complexity | 0ec3418e6c2e6b89c24cffd4322b6368 MD5 | raw file
 1# mmap(2) blacklisting.  Some platforms provide the mmap library routine
 2# but don't support all of the features we need from it.
 3AC_DEFUN([AC_FUNC_MMAP_BLACKLIST],
 4[
 5AC_CHECK_HEADER([sys/mman.h],
 6		[libffi_header_sys_mman_h=yes], [libffi_header_sys_mman_h=no])
 7AC_CHECK_FUNC([mmap], [libffi_func_mmap=yes], [libffi_func_mmap=no])
 8if test "$libffi_header_sys_mman_h" != yes \
 9 || test "$libffi_func_mmap" != yes; then
10   ac_cv_func_mmap_file=no
11   ac_cv_func_mmap_dev_zero=no
12   ac_cv_func_mmap_anon=no
13else
14   AC_CACHE_CHECK([whether read-only mmap of a plain file works],
15  ac_cv_func_mmap_file,
16  [# Add a system to this blacklist if
17   # mmap(0, stat_size, PROT_READ, MAP_PRIVATE, fd, 0) doesn't return a
18   # memory area containing the same data that you'd get if you applied
19   # read() to the same fd.  The only system known to have a problem here
20   # is VMS, where text files have record structure.
21   case "$host_os" in
22     vms* | ultrix*)
23	ac_cv_func_mmap_file=no ;;
24     *)
25	ac_cv_func_mmap_file=yes;;
26   esac])
27   AC_CACHE_CHECK([whether mmap from /dev/zero works],
28  ac_cv_func_mmap_dev_zero,
29  [# Add a system to this blacklist if it has mmap() but /dev/zero
30   # does not exist, or if mmapping /dev/zero does not give anonymous
31   # zeroed pages with both the following properties:
32   # 1. If you map N consecutive pages in with one call, and then
33   #    unmap any subset of those pages, the pages that were not
34   #    explicitly unmapped remain accessible.
35   # 2. If you map two adjacent blocks of memory and then unmap them
36   #    both at once, they must both go away.
37   # Systems known to be in this category are Windows (all variants),
38   # VMS, and Darwin.
39   case "$host_os" in
40     vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00)
41	ac_cv_func_mmap_dev_zero=no ;;
42     *)
43	ac_cv_func_mmap_dev_zero=yes;;
44   esac])
45
46   # Unlike /dev/zero, the MAP_ANON(YMOUS) defines can be probed for.
47   AC_CACHE_CHECK([for MAP_ANON(YMOUS)], ac_cv_decl_map_anon,
48    [AC_TRY_COMPILE(
49[#include <sys/types.h>
50#include <sys/mman.h>
51#include <unistd.h>
52
53#ifndef MAP_ANONYMOUS
54#define MAP_ANONYMOUS MAP_ANON
55#endif
56],
57[int n = MAP_ANONYMOUS;],
58    ac_cv_decl_map_anon=yes,
59    ac_cv_decl_map_anon=no)])
60
61   if test $ac_cv_decl_map_anon = no; then
62     ac_cv_func_mmap_anon=no
63   else
64     AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works],
65     ac_cv_func_mmap_anon,
66  [# Add a system to this blacklist if it has mmap() and MAP_ANON or
67   # MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
68   # doesn't give anonymous zeroed pages with the same properties listed
69   # above for use of /dev/zero.
70   # Systems known to be in this category are Windows, VMS, and SCO Unix.
71   case "$host_os" in
72     vms* | cygwin* | pe | mingw* | sco* | udk* )
73	ac_cv_func_mmap_anon=no ;;
74     *)
75	ac_cv_func_mmap_anon=yes;;
76   esac])
77   fi
78fi
79
80if test $ac_cv_func_mmap_file = yes; then
81  AC_DEFINE(HAVE_MMAP_FILE, 1,
82	    [Define if read-only mmap of a plain file works.])
83fi
84if test $ac_cv_func_mmap_dev_zero = yes; then
85  AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1,
86	    [Define if mmap of /dev/zero works.])
87fi
88if test $ac_cv_func_mmap_anon = yes; then
89  AC_DEFINE(HAVE_MMAP_ANON, 1,
90	    [Define if mmap with MAP_ANON(YMOUS) works.])
91fi
92])