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| 1 dnl ---------------------------------------------------------------------- |
| 2 dnl This whole bit snagged from gcc |
| 3 |
| 4 dnl |
| 5 dnl mmap(2) blacklisting. Some platforms provide the mmap library routine |
| 6 dnl but don't support all of the features we need from it. |
| 7 dnl |
| 8 AC_DEFUN([GCC_AC_FUNC_MMAP_BLACKLIST], |
| 9 [ |
| 10 AC_CHECK_HEADER([sys/mman.h], |
| 11 [gcc_header_sys_mman_h=yes], [gcc_header_sys_mman_h=no]) |
| 12 AC_CHECK_FUNC([mmap], [gcc_func_mmap=yes], [gcc_func_mmap=no]) |
| 13 if 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 |
| 18 else |
| 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 |
| 83 fi |
| 84 |
| 85 if 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.]) |
| 88 fi |
| 89 if 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.]) |
| 92 fi |
| 93 if test $gcc_cv_func_mmap_anon = yes; then |
| 94 AC_DEFINE(HAVE_MMAP_ANON, 1, |
| 95 [Define if mmap with MAP_ANON(YMOUS) works.]) |
| 96 fi |
| 97 ]) |
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