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