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 ]) 98
