1 # mmap-anon.m4 serial 10 2 dnl Copyright (C) 2005, 2007, 2009-2012 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 Mac OS 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 Persuade glibc <sys/mman.h> to define MAP_ANONYMOUS. 19 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) 20 21 # Check for mmap(). Don't use AC_FUNC_MMAP, because it checks too much: it 22 # fails on HP-UX 11, because MAP_FIXED mappings do not work. But this is 23 # irrelevant for anonymous mappings. 24 AC_CHECK_FUNC([mmap], [gl_have_mmap=yes], [gl_have_mmap=no]) 25 26 # Try to allow MAP_ANONYMOUS. 27 gl_have_mmap_anonymous=no 28 if test $gl_have_mmap = yes; then 29 AC_MSG_CHECKING([for MAP_ANONYMOUS]) 30 AC_EGREP_CPP([I cannot identify this map], [ 31 #include <sys/mman.h> 32 #ifdef MAP_ANONYMOUS 33 I cannot identify this map 34 #endif 35 ], 36 [gl_have_mmap_anonymous=yes]) 37 if test $gl_have_mmap_anonymous != yes; then 38 AC_EGREP_CPP([I cannot identify this map], [ 39 #include <sys/mman.h> 40 #ifdef MAP_ANON 41 I cannot identify this map 42 #endif 43 ], 44 [AC_DEFINE([MAP_ANONYMOUS], [MAP_ANON], 45 [Define to a substitute value for mmap()'s MAP_ANONYMOUS flag.]) 46 gl_have_mmap_anonymous=yes]) 47 fi 48 AC_MSG_RESULT([$gl_have_mmap_anonymous]) 49 if test $gl_have_mmap_anonymous = yes; then 50 AC_DEFINE([HAVE_MAP_ANONYMOUS], [1], 51 [Define to 1 if mmap()'s MAP_ANONYMOUS flag is available after including 52 config.h and <sys/mman.h>.]) 53 fi 54 fi 55 ]) 56
