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111
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1 dnl ----------------------------------------------------------------------
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2 dnl This whole bit snagged from gcc
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3
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4 dnl
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5 dnl mmap(2) blacklisting. Some platforms provide the mmap library routine
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6 dnl but don't support all of the features we need from it.
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7 dnl
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8 AC_DEFUN([GCC_AC_FUNC_MMAP_BLACKLIST],
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9 [
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10 AC_CHECK_HEADER([sys/mman.h],
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11 [gcc_header_sys_mman_h=yes], [gcc_header_sys_mman_h=no])
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12 AC_CHECK_FUNC([mmap], [gcc_func_mmap=yes], [gcc_func_mmap=no])
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13 if test "$gcc_header_sys_mman_h" != yes \
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14 || test "$gcc_func_mmap" != yes; then
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15 gcc_cv_func_mmap_file=no
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16 gcc_cv_func_mmap_dev_zero=no
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17 gcc_cv_func_mmap_anon=no
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18 else
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19 AC_CACHE_CHECK([whether read-only mmap of a plain file works],
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20 gcc_cv_func_mmap_file,
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21 [# Add a system to this blacklist if
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22 # mmap(0, stat_size, PROT_READ, MAP_PRIVATE, fd, 0) doesn't return a
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23 # memory area containing the same data that you'd get if you applied
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24 # read() to the same fd. The only system known to have a problem here
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25 # is VMS, where text files have record structure.
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26 case "$host_os" in
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27 *vms* | ultrix*)
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28 gcc_cv_func_mmap_file=no ;;
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29 *)
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30 gcc_cv_func_mmap_file=yes;;
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31 esac])
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32 AC_CACHE_CHECK([whether mmap from /dev/zero works],
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33 gcc_cv_func_mmap_dev_zero,
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34 [# Add a system to this blacklist if it has mmap() but /dev/zero
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35 # does not exist, or if mmapping /dev/zero does not give anonymous
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36 # zeroed pages with both the following properties:
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37 # 1. If you map N consecutive pages in with one call, and then
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38 # unmap any subset of those pages, the pages that were not
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39 # explicitly unmapped remain accessible.
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40 # 2. If you map two adjacent blocks of memory and then unmap them
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41 # both at once, they must both go away.
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42 # Systems known to be in this category are Windows (all variants),
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43 # VMS, and Darwin.
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44 case "$host_os" in
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45 *vms* | cygwin* | pe | mingw* | darwin* | ultrix* | hpux10* | hpux11.00)
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46 gcc_cv_func_mmap_dev_zero=no ;;
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47 *)
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48 gcc_cv_func_mmap_dev_zero=yes;;
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49 esac])
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50
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51 # Unlike /dev/zero, the MAP_ANON(YMOUS) defines can be probed for.
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52 AC_CACHE_CHECK([for MAP_ANON(YMOUS)], gcc_cv_decl_map_anon,
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53 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
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54 [#include <sys/types.h>
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55 #include <sys/mman.h>
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56 #include <unistd.h>
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57
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58 #ifndef MAP_ANONYMOUS
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59 #define MAP_ANONYMOUS MAP_ANON
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60 #endif
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61 ],
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62 [int n = MAP_ANONYMOUS;])],
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63 gcc_cv_decl_map_anon=yes,
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64 gcc_cv_decl_map_anon=no)])
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65
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66 if test $gcc_cv_decl_map_anon = no; then
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67 gcc_cv_func_mmap_anon=no
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68 else
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69 AC_CACHE_CHECK([whether mmap with MAP_ANON(YMOUS) works],
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70 gcc_cv_func_mmap_anon,
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71 [# Add a system to this blacklist if it has mmap() and MAP_ANON or
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72 # MAP_ANONYMOUS, but using mmap(..., MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
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73 # doesn't give anonymous zeroed pages with the same properties listed
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74 # above for use of /dev/zero.
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75 # Systems known to be in this category are Windows, VMS, and SCO Unix.
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76 case "$host_os" in
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77 *vms* | cygwin* | pe | mingw* | sco* | udk* )
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78 gcc_cv_func_mmap_anon=no ;;
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79 *)
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80 gcc_cv_func_mmap_anon=yes;;
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81 esac])
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82 fi
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83 fi
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84
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85 if test $gcc_cv_func_mmap_file = yes; then
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86 AC_DEFINE(HAVE_MMAP_FILE, 1,
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87 [Define if read-only mmap of a plain file works.])
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88 fi
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89 if test $gcc_cv_func_mmap_dev_zero = yes; then
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90 AC_DEFINE(HAVE_MMAP_DEV_ZERO, 1,
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91 [Define if mmap of /dev/zero works.])
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92 fi
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93 if test $gcc_cv_func_mmap_anon = yes; then
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94 AC_DEFINE(HAVE_MMAP_ANON, 1,
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95 [Define if mmap with MAP_ANON(YMOUS) works.])
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96 fi
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97 ])
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