1 # mmap-anon.m4 serial 8 2 dnl Copyright (C) 2005, 2007, 2009 Free Software Foundation, Inc. 3 dnl This file is free software; the Free Software Foundation 4 dnl gives unlimited permission to copy and/or distribute it, 5 dnl with or without modifications, as long as this notice is preserved. 6 7 # Detect how mmap can be used to create anonymous (not file-backed) memory 8 # mappings. 9 # - On Linux, AIX, OSF/1, Solaris, Cygwin, Interix, Haiku, both MAP_ANONYMOUS 10 # and MAP_ANON exist and have the same value. 11 # - On HP-UX, only MAP_ANONYMOUS exists. 12 # - On MacOS X, FreeBSD, NetBSD, OpenBSD, only MAP_ANON exists. 13 # - On IRIX, neither exists, and a file descriptor opened to /dev/zero must be 14 # used. 15 16 AC_DEFUN([gl_FUNC_MMAP_ANON], 17 [ 18 dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57. 19 AC_REQUIRE([AC_PROG_CPP]) 20 AC_REQUIRE([AC_PROG_EGREP]) 21 22 dnl Persuade glibc <sys/mman.h> to define MAP_ANONYMOUS. 23 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) 24 25 # Check for mmap(). Don't use AC_FUNC_MMAP, because it checks too much: it 26 # fails on HP-UX 11, because MAP_FIXED mappings do not work. But this is 27 # irrelevant for anonymous mappings. 28 AC_CHECK_FUNC([mmap], [gl_have_mmap=yes], [gl_have_mmap=no]) 29 30 # Try to allow MAP_ANONYMOUS. 31 gl_have_mmap_anonymous=no 32 if test $gl_have_mmap = yes; then 33 AC_MSG_CHECKING([for MAP_ANONYMOUS]) 34 AC_EGREP_CPP([I cant identify this map.], [ 35 #include <sys/mman.h> 36 #ifdef MAP_ANONYMOUS 37 I cant identify this map. 38 #endif 39 ], 40 [gl_have_mmap_anonymous=yes]) 41 if test $gl_have_mmap_anonymous != yes; then 42 AC_EGREP_CPP([I cant identify this map.], [ 43 #include <sys/mman.h> 44 #ifdef MAP_ANON 45 I cant identify this map. 46 #endif 47 ], 48 [AC_DEFINE([MAP_ANONYMOUS], [MAP_ANON], 49 [Define to a substitute value for mmap()'s MAP_ANONYMOUS flag.]) 50 gl_have_mmap_anonymous=yes]) 51 fi 52 AC_MSG_RESULT([$gl_have_mmap_anonymous]) 53 if test $gl_have_mmap_anonymous = yes; then 54 AC_DEFINE([HAVE_MAP_ANONYMOUS], [1], 55 [Define to 1 if mmap()'s MAP_ANONYMOUS flag is available after including 56 config.h and <sys/mman.h>.]) 57 fi 58 fi 59 ]) 60
