X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fmmap-anon.m4;h=7ba7fd26b6cde7f3f99713920627750fd3d2d43c;hb=06a366de002272748bd110dcd4da6d967ff57d46;hp=fd8a5370b37ab9e71867d34148d8c505298c1358;hpb=e34add1b47c74f3f002058952dda27ee5dea2b80;p=gnulib.git

diff --git a/m4/mmap-anon.m4 b/m4/mmap-anon.m4
index fd8a5370b..7ba7fd26b 100644
--- a/m4/mmap-anon.m4
+++ b/m4/mmap-anon.m4
@@ -1,24 +1,31 @@
-# mmap-anon.m4 serial 3
-dnl Copyright (C) 2005 Free Software Foundation, Inc.
+# mmap-anon.m4 serial 9
+dnl Copyright (C) 2005, 2007, 2009-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
 
+# Detect how mmap can be used to create anonymous (not file-backed) memory
+# mappings.
+# - On Linux, AIX, OSF/1, Solaris, Cygwin, Interix, Haiku, both MAP_ANONYMOUS
+#   and MAP_ANON exist and have the same value.
+# - On HP-UX, only MAP_ANONYMOUS exists.
+# - On MacOS X, FreeBSD, NetBSD, OpenBSD, only MAP_ANON exists.
+# - On IRIX, neither exists, and a file descriptor opened to /dev/zero must be
+#   used.
+
 AC_DEFUN([gl_FUNC_MMAP_ANON],
 [
-  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
-  AC_REQUIRE([AC_PROG_CPP])
-  AC_REQUIRE([AC_PROG_EGREP])
-
   dnl Persuade glibc <sys/mman.h> to define MAP_ANONYMOUS.
-  AC_REQUIRE([AC_GNU_SOURCE])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
-  # Check for mmap()
-  AC_FUNC_MMAP
+  # Check for mmap(). Don't use AC_FUNC_MMAP, because it checks too much: it
+  # fails on HP-UX 11, because MAP_FIXED mappings do not work. But this is
+  # irrelevant for anonymous mappings.
+  AC_CHECK_FUNC([mmap], [gl_have_mmap=yes], [gl_have_mmap=no])
 
   # Try to allow MAP_ANONYMOUS.
   gl_have_mmap_anonymous=no
-  if test $ac_cv_func_mmap_fixed_mapped = yes; then
+  if test $gl_have_mmap = yes; then
     AC_MSG_CHECKING([for MAP_ANONYMOUS])
     AC_EGREP_CPP([I cant identify this map.], [
 #include <sys/mman.h>
@@ -34,13 +41,13 @@ AC_DEFUN([gl_FUNC_MMAP_ANON],
     I cant identify this map.
 #endif
 ],
-        [AC_DEFINE(MAP_ANONYMOUS, MAP_ANON,
+        [AC_DEFINE([MAP_ANONYMOUS], [MAP_ANON],
           [Define to a substitute value for mmap()'s MAP_ANONYMOUS flag.])
          gl_have_mmap_anonymous=yes])
     fi
-    AC_MSG_RESULT($gl_have_mmap_anonymous)
+    AC_MSG_RESULT([$gl_have_mmap_anonymous])
     if test $gl_have_mmap_anonymous = yes; then
-      AC_DEFINE(HAVE_MAP_ANONYMOUS, 1,
+      AC_DEFINE([HAVE_MAP_ANONYMOUS], [1],
         [Define to 1 if mmap()'s MAP_ANONYMOUS flag is available after including
          config.h and <sys/mman.h>.])
     fi