/* $NetBSD: featuretest.h,v 1.16 2026/06/30 20:05:54 riastradh Exp $ */ /* * Written by Klaus Klein <kleink@NetBSD.org>, February 2, 1998. * Public domain. * * NOTE: Do not protect this header against multiple inclusion. Doing * so can have subtle side-effects due to header file inclusion order * and testing of e.g. _POSIX_SOURCE vs. _POSIX_C_SOURCE. Instead, * protect each CPP macro that we want to supply. */ /* * Feature-test macros are defined by several standards, and allow an * application to specify what symbols they want the system headers to * expose, and hence what standard they want them to conform to. * * A header file MUST NOT expose symbols that are not requested by a * feature test macro, unless they appear in the earliest revision of * the standard introducing the header file, or the header file is * entirely NetBSD-specific. In the absence of any _ANSI_*, _POSIX_*, * or _XOPEN_*, feature test macros, we define _NETBSD_SOURCE by * default. * * There are two classes of feature-test macros. The first class * specify complete standards, and if one of these is defined, header * files will try to conform to the relevant standard. They are: * * ANSI macros: * _ANSI_SOURCE ANSI C89 * * POSIX macros: * _POSIX_SOURCE == 1 IEEE Std 1003.1 [POSIX.1-1990] * _POSIX_C_SOURCE == 1 IEEE Std 1003.1-1990 [citation needed] * _POSIX_C_SOURCE == 2 IEEE Std 1003.2-1992 [citation needed] * _POSIX_C_SOURCE == 199309L IEEE Std 1003.1b-1993 [citation needed] * _POSIX_C_SOURCE == 199506L ISO/IEC 9945-1:1996 [POSIX.1-1995] * _POSIX_C_SOURCE == 200112L IEEE Std 1003.1-2001 (Issue 6) [POSIX.1-2001] * _POSIX_C_SOURCE == 200809L IEEE Std 1003.1-2008 (Issue 7) [POSIX.1-2008] * _POSIX_C_SOURCE == 202405L IEEE Std 1003.1-2024 (Issue 8) [POSIX.1-2024] * * X/Open macros: * _XOPEN_SOURCE * X/Open System Interfaces & Headers, Issue 4, Ver 2 [XOPEN4.2-XSH] * _XOPEN_SOURCE_EXTENDED == 1 * X/Open XSH4.2 UNIX extensions [XOPEN4.2-XSH] * _XOPEN_SOURCE == 500 * SUSv2 System Interfaces & Headers, Issue 5 [SUSv2-1997] * _XOPEN_SOURCE == 520 * Networking Services (XNS), Issue 5.2 [XOPEN5.2-XNS] * _XOPEN_SOURCE == 600 * IEEE Std 1003.1-2001 (Issue 6), XSI option [POSIX.1-2001] * _XOPEN_SOURCE == 700 * IEEE Std 1003.1-2008 (Issue 7), XSI option [POSIX.1-2008] * _XOPEN_SOURCE == 800 * IEEE Std 1003.1-2024 (Issue 8), XSI option [POSIX.1-2024] * * References: * * [POSIX.1-1990] Portable Operating System Interface (POSIX) -- * Part 1: System Application Program Interface (API) [C * Language], IEEE Std 1003.1, First Edition, 1990-12-07, ISBN * 1-55937-061-0, Sec. 2.7.1 `POSIX.1 Symbols', p. 31. * https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub151-2.pdf#page=52 * https://web.archive.org/web/20260330002540/https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub151-2.pdf * * [XOPEN4.2-XSH] X/Open CAE Specification, Volume XSH: System * Interfaces and Headers Issue 4, Version 2, The Open Group, * 1994, Document Number: C435, ISBN 1-85912-037-7, Sec. 2.2 * `The Compilation Environment', pp. 17-18. * https://pubs.opengroup.org/onlinepubs/9695969499/toc.pdf#page=45 * * [POSIX.1-1995] Portable Operating System Interface (POSIX) -- * Part 1: System Application Program Interface (API) [C * Language], IEEE Std. 1003.1, 1996 Edition, 1996-07-12, ISBN * 1-55937-573-6, Sec 2.7.2 `POSIX.1 Symbols', p. 30. * * [SUSv2-1997] The Single UNIX Specification, Version 2, Volume * XSH: System Interfaces, The Open Group, 1997, Sec. `The * Compilation Environment'. * https://pubs.opengroup.org/onlinepubs/7990989775/xsh/compilation.html * * [XOPEN5.2-XNS] Networking Services (XNS), Issue 5.2, The Open * Group, 1999, Document Number: C808, ISBN 1-85912-241-8, * Sec. `The Compilation Environment'. * https://pubs.opengroup.org/onlinepubs/009619199/chap1.htm#tagcjh_02_03 * * [POSIX.1-2001] The Open Group Base Specifications Issue 6, * Volume XSH: System Interfaces, IEEE Std 1003.1, 2004 * Edition, The IEEE and The Open Group, 2004 Sec. 2.2 `The * Compilation Environment'. * https://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_02.html * * [POSIX.1-2008] The Open Group Base Specifications Issue 7, * Volume XSH: System Interfaces, IEEE Std 1003.1-2017 * (Revision of IEEE Std 1003.1-2008), The IEEE and The Open * Group, Sec. 2.2 `The Compilation Environment'. * https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_02_01 * * [POSIX.1-2024] The Open Group Base Specifications Issue 8, * Volume XSH: System Interfaces, IEEE Std 1003.1-2024, The * IEEE and The Open Group, 2024, System Interfaces Sec. 2.2 * `The Compilation Environment'. * https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/V2_chap02.html#tag_16_02 * * NetBSD macros: * _NETBSD_SOURCE == 1 Make all NetBSD features available. * * If more than one of these "major" feature-test macros is defined, * then the set of facilities provided (and namespace used) is the * union of that specified by the relevant standards, and in case of * conflict, the earlier standard in the above list has precedence (so * if both _POSIX_C_SOURCE and _NETBSD_SOURCE are defined, the version * of rename() that's used is the POSIX one). If none of the "major" * feature-test macros is defined, _NETBSD_SOURCE is assumed. * * There are also "minor" feature-test macros, which enable extra * functionality in addition to some base standard. They should be * defined along with one of the "major" macros. The "minor" macros * are: * * _REENTRANT Some thread-safety extensions like lgamma_r(3) * (mostly subsumed by _POSIX_C_SOURCE >= 199506L) * _ISOC99_SOURCE C99 extensions like snprintf without -std=c99 * _ISOC11_SOURCE C11 extensions like aligned_alloc without -std=c11 * _ISOC23_SOURCE C23 extensions like mbrtoc8 without -std=c23 * _OPENBSD_SOURCE Nonstandard OpenBSD extensions like strtonum(3) * _GNU_SOURCE Nonstandard GNU extensions like feenableexcept(3) */ #if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE) #define _POSIX_C_SOURCE 1L #endif #if !defined(_ANSI_SOURCE) && !defined(_POSIX_C_SOURCE) && \ !defined(_XOPEN_SOURCE) && !defined(_NETBSD_SOURCE) #define _NETBSD_SOURCE 1 #endif #if ((_POSIX_C_SOURCE - 0) >= 199506L || (_XOPEN_SOURCE - 0) >= 500) && \ !defined(_REENTRANT) #define _REENTRANT #endif /* * The _XOPEN_SOURCE namespaces are supersets of corresponding * _POSIX_C_SOURCE namespaces, so to keep the namespace tests in header * files simpler, if _XOPEN_SOURCE is defined but _POSIX_C_SOURCE is * not, define _POSIX_C_SOURCE to the corresponding value. */ #if defined(_XOPEN_SOURCE) && !defined(_POSIX_C_SOURCE) /* * `[I]f _XOPEN_SOURCE is set equal to 800 and _POSIX_C_SOURCE is set * equal to 202405L, the behavior is the same as if only _XOPEN_SOURCE * is defined and set equal to 800. * * IEEE Std 1003.1-2024, 2.2.1.2 `The _XOPEN_SOURCE Feature Test Macro' * https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/V2_chap02.html#tag_16_02_01_02 */ #if (_XOPEN_SOURCE - 0) == 800 #define _POSIX_C_SOURCE 202405L /* * `[I]f _XOPEN_SOURCE is set equal to 700 and _POSIX_C_SOURCE is set * equal to 200809L, the behavior is the same as if only _XOPEN_SOURCE * is defined and set equal to 700.' * * IEEE Std 1003.1-2008, 2.2.1 `POSIX.1 Symbols', subsection `The * _XOPEN_SOURCE Feature Test Macro' * https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/functions/V2_chap02.html */ #elif (_XOPEN_SOURCE - 0) == 700 #define _POSIX_C_SOURCE 200809L /* * `[I]f _XOPEN_SOURCE is set equal to 600 and _POSIX_C_SOURCE is set * equal to 200112L, the behavior is the same as if only _XOPEN_SOURCE * is defined and set equal to 600.' * * IEEE Std 1003.1-2001, 2.2.1 `POSIX.1 Symbols', subsection `The * _XOPEN_SOURCE Feature Test Macro' * https://pubs.opengroup.org/onlinepubs/007904875/functions/xsh_chap02_02.html */ #elif (_XOPEN_SOURCE - 0) == 600 #define _POSIX_C_SOURCE 200112L /* * `[I]f _XOPEN_SOURCE is set equal to 500 and _POSIX_SOURCE is * defined, or _POSIX_C_SOURCE is set greater than zero and less than * or equal to 199506L, the behaviour is the same as if only * _XOPEN_SOURCE is defined and set equal to 500.' * * Single UNIX Specification, Version 2, `The Compilation Environment' * https://pubs.opengroup.org/onlinepubs/007908799/xsh/compilation.html */ #elif (_XOPEN_SOURCE - 0) >= 500 #define _POSIX_C_SOURCE 199506L #endif #endif
