| dnl ---------------------------------------------------------------------- |
| dnl This whole bit snagged from gcc |
| |
| dnl |
| dnl mmap(2) blacklisting. Some platforms provide the mmap library routine |
| dnl but don't support all of the features we need from it. |
| dnl |
| AC_DEFUN([GCC_AC_FUNC_MMAP_BLACKLIST], |
| [ |
| AC_CHECK_HEADER([sys/mman.h], |
| [gcc_header_sys_mman_h=yes], [gcc_header_sys_mman_h=no]) |
| AC_CHECK_FUNC([mmap], [gcc_func_mmap=yes], [gcc_func_mmap=no]) |
| if test "$gcc_header_sys_mman_h" != yes \ |
| || test "$gcc_func_mmap" != yes; then |
| gcc_cv_func_mmap_file=no |
| gcc_cv_func_mmap_dev_zero=no |
| gcc_cv_func_mmap_anon=no |
| else |
| AC_CACHE_CHECK([whether read-only mmap of a plain file works], |
| gcc_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 "$host_os" in |
| *vms* | ultrix*) |
| gcc_cv_func_mmap_file=no ;; |
| *) |
| gcc_cv_func_mmap_file=yes;; |
| esac]) |
| AC_CACHE_CHECK([whether mmap from /dev/zero works], |
| gcc_cv_func_mmap_dev_zero, |
| [# Add a system to this blacklist if it has mmap() but /dev/zero |
| # does not exist, or if mmapping /dev/zero does not give anonymous |
| # zeroed pages with both the following properties: |
| # 1. If you map N consecutive pages in with one call, and then |
| # unmap any subset of those pages, the pages that were not |
| # explicitly unmapped remain accessible. |
| # 2. If you map two adjacent blocks of memory and then unmap them |
| # both at once, they must both go away. |
| # Systems known to be in this category are Windows (all variants), |
| # VMS, and Darwin. |
| case "$host_os" in |
| *vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00) |
| gcc_cv_func_mmap_dev_zero=no ;; |
| *) |
| gcc_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)], gcc_cv_decl_map_anon, |
| [AC_COMPILE_IFELSE([AC_LANG_PROGRAM( |
| [#include <sys/types.h> |
| #include <sys/mman.h> |
| #include <unistd.h> |
| |
| #ifndef MAP_ANONYMOUS |
| #define MAP_ANONYMOUS MAP_ANON |
| #endif |
| ], |
| [int n = MAP_ANONYMOUS;])], |
| gcc_cv_decl_map_anon=yes, |
| gcc_cv_decl_map_anon=no)]) |
| |
| if test $gcc_cv_decl_map_anon = no; then |
| gcc_cv_func_mmap_anon=no |
| else |
| AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works], |
| gcc_cv_func_mmap_anon, |
| [# Add a system to this blacklist if it has mmap() and MAP_ANON or |
| # MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) |
| # doesn't give anonymous zeroed pages with the same properties listed |
| # above for use of /dev/zero. |
| # Systems known to be in this category are Windows, VMS, and SCO Unix. |
| case "$host_os" in |
| *vms* | cygwin* | pe | mingw* | sco* | udk* ) |
| gcc_cv_func_mmap_anon=no ;; |
| *) |
| gcc_cv_func_mmap_anon=yes;; |
| esac]) |
| fi |
| fi |
| |
| if test $gcc_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 $gcc_cv_func_mmap_dev_zero = yes; then |
| AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1, |
| [Define if mmap of /dev/zero works.]) |
| fi |
| if test $gcc_cv_func_mmap_anon = yes; then |
| AC_DEFINE(HAVE_MMAP_ANON, 1, |
| [Define if mmap with MAP_ANON(YMOUS) works.]) |
| fi |
| ]) |