# 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_FUNC_MMAP_BLACKLIST], [ AC_CHECK_HEADER([sys/mman.h], [libffi_header_sys_mman_h=yes], [libffi_header_sys_mman_h=no]) AC_CHECK_FUNC([mmap], [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 ])