master
1/* $NetBSD: featuretest.h,v 1.10.66.1 2024/10/11 18:51:20 martin Exp $ */
2
3/*
4 * Written by Klaus Klein <kleink@NetBSD.org>, February 2, 1998.
5 * Public domain.
6 *
7 * NOTE: Do not protect this header against multiple inclusion. Doing
8 * so can have subtle side-effects due to header file inclusion order
9 * and testing of e.g. _POSIX_SOURCE vs. _POSIX_C_SOURCE. Instead,
10 * protect each CPP macro that we want to supply.
11 */
12
13/*
14 * Feature-test macros are defined by several standards, and allow an
15 * application to specify what symbols they want the system headers to
16 * expose, and hence what standard they want them to conform to.
17 * There are two classes of feature-test macros. The first class
18 * specify complete standards, and if one of these is defined, header
19 * files will try to conform to the relevant standard. They are:
20 *
21 * ANSI macros:
22 * _ANSI_SOURCE ANSI C89
23 *
24 * POSIX macros:
25 * _POSIX_SOURCE == 1 IEEE Std 1003.1 (version?)
26 * _POSIX_C_SOURCE == 1 IEEE Std 1003.1-1990
27 * _POSIX_C_SOURCE == 2 IEEE Std 1003.2-1992
28 * _POSIX_C_SOURCE == 199309L IEEE Std 1003.1b-1993
29 * _POSIX_C_SOURCE == 199506L ISO/IEC 9945-1:1996
30 * _POSIX_C_SOURCE == 200112L IEEE Std 1003.1-2001
31 * _POSIX_C_SOURCE == 200809L IEEE Std 1003.1-2008
32 *
33 * X/Open macros:
34 * _XOPEN_SOURCE System Interfaces and Headers, Issue 4, Ver 2
35 * _XOPEN_SOURCE_EXTENDED == 1 XSH4.2 UNIX extensions
36 * _XOPEN_SOURCE == 500 System Interfaces and Headers, Issue 5
37 * _XOPEN_SOURCE == 520 Networking Services (XNS), Issue 5.2
38 * _XOPEN_SOURCE == 600 IEEE Std 1003.1-2001, XSI option
39 * _XOPEN_SOURCE == 700 IEEE Std 1003.1-2008, XSI option
40 *
41 * NetBSD macros:
42 * _NETBSD_SOURCE == 1 Make all NetBSD features available.
43 *
44 * If more than one of these "major" feature-test macros is defined,
45 * then the set of facilities provided (and namespace used) is the
46 * union of that specified by the relevant standards, and in case of
47 * conflict, the earlier standard in the above list has precedence (so
48 * if both _POSIX_C_SOURCE and _NETBSD_SOURCE are defined, the version
49 * of rename() that's used is the POSIX one). If none of the "major"
50 * feature-test macros is defined, _NETBSD_SOURCE is assumed.
51 *
52 * There are also "minor" feature-test macros, which enable extra
53 * functionality in addition to some base standard. They should be
54 * defined along with one of the "major" macros. The "minor" macros
55 * are:
56 *
57 * _REENTRANT
58 * _ISOC99_SOURCE
59 * _ISOC11_SOURCE
60 * _LARGEFILE_SOURCE Large File Support
61 * <http://ftp.sas.com/standards/large.file/x_open.20Mar96.html>
62 */
63
64#if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE)
65#define _POSIX_C_SOURCE 1L
66#endif
67
68#if !defined(_ANSI_SOURCE) && !defined(_POSIX_C_SOURCE) && \
69 !defined(_XOPEN_SOURCE) && !defined(_NETBSD_SOURCE)
70#define _NETBSD_SOURCE 1
71#endif
72
73#if ((_POSIX_C_SOURCE - 0) >= 199506L || (_XOPEN_SOURCE - 0) >= 500) && \
74 !defined(_REENTRANT)
75#define _REENTRANT
76#endif
77
78/*
79 * The _XOPEN_SOURCE namespaces are supersets of corresponding
80 * _POSIX_C_SOURCE namespaces, so to keep the namespace tests in header
81 * files simpler, if _XOPEN_SOURCE is defined but _POSIX_C_SOURCE is
82 * not, define _POSIX_C_SOURCE to the corresponding value.
83 */
84#if defined(_XOPEN_SOURCE) && !defined(_POSIX_C_SOURCE)
85
86/*
87 * `[I]f _XOPEN_SOURCE is set equal to 800 and _POSIX_C_SOURCE is set
88 * equal to 202405L, the behavior is the same as if only _XOPEN_SOURCE
89 * is defined and set equal to 800.
90 *
91 * IEEE Std 1003.1-2024, 2.2.1.2 `The _XOPEN_SOURCE Feature Test Macro'
92 * https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/V2_chap02.html#tag_16_02_01_02
93 */
94#if (_XOPEN_SOURCE - 0) == 800
95#define _POSIX_C_SOURCE 202405L
96
97/*
98 * `[I]f _XOPEN_SOURCE is set equal to 700 and _POSIX_C_SOURCE is set
99 * equal to 200809L, the behavior is the same as if only _XOPEN_SOURCE
100 * is defined and set equal to 700.'
101 *
102 * IEEE Std 1003.1-2008, 2.2.1 `POSIX.1 Symbols', subsection `The
103 * _XOPEN_SOURCE Feature Test Macro'
104 * https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/functions/V2_chap02.html
105 */
106#elif (_XOPEN_SOURCE - 0) == 700
107#define _POSIX_C_SOURCE 200809L
108
109/*
110 * `[I]f _XOPEN_SOURCE is set equal to 600 and _POSIX_C_SOURCE is set
111 * equal to 200112L, the behavior is the same as if only _XOPEN_SOURCE
112 * is defined and set equal to 600.'
113 *
114 * IEEE Std 1003.1-2001, 2.2.1 `POSIX.1 Symbols', subsection `The
115 * _XOPEN_SOURCE Feature Test Macro'
116 * https://pubs.opengroup.org/onlinepubs/007904875/functions/xsh_chap02_02.html
117 */
118#elif (_XOPEN_SOURCE - 0) == 600
119#define _POSIX_C_SOURCE 200112L
120
121/*
122 * `[I]f _XOPEN_SOURCE is set equal to 500 and _POSIX_SOURCE is
123 * defined, or _POSIX_C_SOURCE is set greater than zero and less than
124 * or equal to 199506L, the behaviour is the same as if only
125 * _XOPEN_SOURCE is defined and set equal to 500.'
126 *
127 * Single UNIX Specification, Version 2, `The Compilation Environment'
128 * https://pubs.opengroup.org/onlinepubs/007908799/xsh/compilation.html
129 */
130#elif (_XOPEN_SOURCE - 0) == 500
131#define _POSIX_C_SOURCE 199506L
132#endif
133
134#endif