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40a73391 | 1 | # mmap-anon.m4 serial 10 |
c0c3707f | 2 | dnl Copyright (C) 2005, 2007, 2009-2019 Free Software Foundation, Inc. |
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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. | |
40a73391 | 12 | # - On Mac OS X, FreeBSD, NetBSD, OpenBSD, only MAP_ANON exists. |
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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 | [ | |
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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]) | |
40a73391 | 30 | AC_EGREP_CPP([I cannot identify this map], [ |
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31 | #include <sys/mman.h> |
32 | #ifdef MAP_ANONYMOUS | |
40a73391 | 33 | I cannot identify this map |
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34 | #endif |
35 | ], | |
36 | [gl_have_mmap_anonymous=yes]) | |
37 | if test $gl_have_mmap_anonymous != yes; then | |
40a73391 | 38 | AC_EGREP_CPP([I cannot identify this map], [ |
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39 | #include <sys/mman.h> |
40 | #ifdef MAP_ANON | |
40a73391 | 41 | I cannot identify this map |
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42 | #endif |
43 | ], | |
44 | [AC_DEFINE([MAP_ANONYMOUS], [MAP_ANON], | |
45 | [Define to a substitute value for mmap()'s MAP_ANONYMOUS flag.]) | |
46 | gl_have_mmap_anonymous=yes]) | |
47 | fi | |
48 | AC_MSG_RESULT([$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 | ]) |