1*a939078aSHiroo HAYASHI# mmap-anon.m4 serial 12 2*a939078aSHiroo HAYASHIdnl Copyright (C) 2005, 2007, 2009-2021 Free Software Foundation, Inc. 3*a939078aSHiroo HAYASHIdnl This file is free software; the Free Software Foundation 4*a939078aSHiroo HAYASHIdnl gives unlimited permission to copy and/or distribute it, 5*a939078aSHiroo HAYASHIdnl with or without modifications, as long as this notice is preserved. 6*a939078aSHiroo HAYASHI 7*a939078aSHiroo HAYASHI# Detect how mmap can be used to create anonymous (not file-backed) memory 8*a939078aSHiroo HAYASHI# mappings. 9*a939078aSHiroo HAYASHI# - On Linux, AIX, OSF/1, Solaris, Cygwin, Interix, Haiku, both MAP_ANONYMOUS 10*a939078aSHiroo HAYASHI# and MAP_ANON exist and have the same value. 11*a939078aSHiroo HAYASHI# - On HP-UX, only MAP_ANONYMOUS exists. 12*a939078aSHiroo HAYASHI# - On Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix, only MAP_ANON exists. 13*a939078aSHiroo HAYASHI# - On IRIX, neither exists, and a file descriptor opened to /dev/zero must be 14*a939078aSHiroo HAYASHI# used. 15*a939078aSHiroo HAYASHI 16*a939078aSHiroo HAYASHIAC_DEFUN_ONCE([gl_FUNC_MMAP_ANON], 17*a939078aSHiroo HAYASHI[ 18*a939078aSHiroo HAYASHI dnl Persuade glibc <sys/mman.h> to define MAP_ANONYMOUS. 19*a939078aSHiroo HAYASHI AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) 20*a939078aSHiroo HAYASHI 21*a939078aSHiroo HAYASHI # Check for mmap(). Don't use AC_FUNC_MMAP, because it checks too much: it 22*a939078aSHiroo HAYASHI # fails on HP-UX 11, because MAP_FIXED mappings do not work. But this is 23*a939078aSHiroo HAYASHI # irrelevant for anonymous mappings. 24*a939078aSHiroo HAYASHI AC_CHECK_FUNC([mmap], [gl_have_mmap=yes], [gl_have_mmap=no]) 25*a939078aSHiroo HAYASHI 26*a939078aSHiroo HAYASHI # Try to allow MAP_ANONYMOUS. 27*a939078aSHiroo HAYASHI gl_have_mmap_anonymous=no 28*a939078aSHiroo HAYASHI if test $gl_have_mmap = yes; then 29*a939078aSHiroo HAYASHI AC_MSG_CHECKING([for MAP_ANONYMOUS]) 30*a939078aSHiroo HAYASHI AC_EGREP_CPP([I cannot identify this map], [ 31*a939078aSHiroo HAYASHI#include <sys/mman.h> 32*a939078aSHiroo HAYASHI#ifdef MAP_ANONYMOUS 33*a939078aSHiroo HAYASHI I cannot identify this map 34*a939078aSHiroo HAYASHI#endif 35*a939078aSHiroo HAYASHI], 36*a939078aSHiroo HAYASHI [gl_have_mmap_anonymous=yes]) 37*a939078aSHiroo HAYASHI if test $gl_have_mmap_anonymous != yes; then 38*a939078aSHiroo HAYASHI AC_EGREP_CPP([I cannot identify this map], [ 39*a939078aSHiroo HAYASHI#include <sys/mman.h> 40*a939078aSHiroo HAYASHI#ifdef MAP_ANON 41*a939078aSHiroo HAYASHI I cannot identify this map 42*a939078aSHiroo HAYASHI#endif 43*a939078aSHiroo HAYASHI], 44*a939078aSHiroo HAYASHI [AC_DEFINE([MAP_ANONYMOUS], [MAP_ANON], 45*a939078aSHiroo HAYASHI [Define to a substitute value for mmap()'s MAP_ANONYMOUS flag.]) 46*a939078aSHiroo HAYASHI gl_have_mmap_anonymous=yes]) 47*a939078aSHiroo HAYASHI fi 48*a939078aSHiroo HAYASHI AC_MSG_RESULT([$gl_have_mmap_anonymous]) 49*a939078aSHiroo HAYASHI if test $gl_have_mmap_anonymous = yes; then 50*a939078aSHiroo HAYASHI AC_DEFINE([HAVE_MAP_ANONYMOUS], [1], 51*a939078aSHiroo HAYASHI [Define to 1 if mmap()'s MAP_ANONYMOUS flag is available after including 52*a939078aSHiroo HAYASHI config.h and <sys/mman.h>.]) 53*a939078aSHiroo HAYASHI fi 54*a939078aSHiroo HAYASHI fi 55*a939078aSHiroo HAYASHI]) 56