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92 lines
3.2 KiB
92 lines
3.2 KiB
# mmap(2) blacklisting. Some platforms provide the mmap library routine |
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# but don't support all of the features we need from it. |
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AC_DEFUN([AC_FUNC_MMAP_BLACKLIST], |
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[ |
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AC_CHECK_HEADER([sys/mman.h], |
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[libffi_header_sys_mman_h=yes], [libffi_header_sys_mman_h=no]) |
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AC_CHECK_FUNC([mmap], [libffi_func_mmap=yes], [libffi_func_mmap=no]) |
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if test "$libffi_header_sys_mman_h" != yes \ |
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|| test "$libffi_func_mmap" != yes; then |
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ac_cv_func_mmap_file=no |
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ac_cv_func_mmap_dev_zero=no |
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ac_cv_func_mmap_anon=no |
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else |
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AC_CACHE_CHECK([whether read-only mmap of a plain file works], |
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ac_cv_func_mmap_file, |
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[# Add a system to this blacklist if |
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# mmap(0, stat_size, PROT_READ, MAP_PRIVATE, fd, 0) doesn't return a |
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# memory area containing the same data that you'd get if you applied |
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# read() to the same fd. The only system known to have a problem here |
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# is VMS, where text files have record structure. |
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case "$host_os" in |
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vms* | ultrix*) |
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ac_cv_func_mmap_file=no ;; |
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*) |
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ac_cv_func_mmap_file=yes;; |
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esac]) |
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AC_CACHE_CHECK([whether mmap from /dev/zero works], |
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ac_cv_func_mmap_dev_zero, |
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[# Add a system to this blacklist if it has mmap() but /dev/zero |
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# does not exist, or if mmapping /dev/zero does not give anonymous |
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# zeroed pages with both the following properties: |
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# 1. If you map N consecutive pages in with one call, and then |
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# unmap any subset of those pages, the pages that were not |
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# explicitly unmapped remain accessible. |
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# 2. If you map two adjacent blocks of memory and then unmap them |
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# both at once, they must both go away. |
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# Systems known to be in this category are Windows (all variants), |
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# VMS, and Darwin. |
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case "$host_os" in |
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vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00) |
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ac_cv_func_mmap_dev_zero=no ;; |
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*) |
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ac_cv_func_mmap_dev_zero=yes;; |
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esac]) |
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# Unlike /dev/zero, the MAP_ANON(YMOUS) defines can be probed for. |
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AC_CACHE_CHECK([for MAP_ANON(YMOUS)], ac_cv_decl_map_anon, |
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[AC_TRY_COMPILE( |
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[#include <sys/types.h> |
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#include <sys/mman.h> |
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#include <unistd.h> |
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#ifndef MAP_ANONYMOUS |
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#define MAP_ANONYMOUS MAP_ANON |
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#endif |
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], |
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[int n = MAP_ANONYMOUS;], |
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ac_cv_decl_map_anon=yes, |
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ac_cv_decl_map_anon=no)]) |
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if test $ac_cv_decl_map_anon = no; then |
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ac_cv_func_mmap_anon=no |
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else |
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AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works], |
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ac_cv_func_mmap_anon, |
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[# Add a system to this blacklist if it has mmap() and MAP_ANON or |
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# MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) |
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# doesn't give anonymous zeroed pages with the same properties listed |
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# above for use of /dev/zero. |
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# Systems known to be in this category are Windows, VMS, and SCO Unix. |
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case "$host_os" in |
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vms* | cygwin* | pe | mingw* | sco* | udk* ) |
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ac_cv_func_mmap_anon=no ;; |
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*) |
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ac_cv_func_mmap_anon=yes;; |
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esac]) |
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fi |
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fi |
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if test $ac_cv_func_mmap_file = yes; then |
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AC_DEFINE(HAVE_MMAP_FILE, 1, |
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[Define if read-only mmap of a plain file works.]) |
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fi |
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if test $ac_cv_func_mmap_dev_zero = yes; then |
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AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1, |
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[Define if mmap of /dev/zero works.]) |
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fi |
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if test $ac_cv_func_mmap_anon = yes; then |
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AC_DEFINE(HAVE_MMAP_ANON, 1, |
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[Define if mmap with MAP_ANON(YMOUS) works.]) |
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fi |
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])
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