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Implement a fine-grain control system which allows header developers

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to control the exposure of macros and prototypes depending upon the
POSIX, X/Open, or ISO C version an application has requested.

Submitted by:	wollman
Reviewed by:	bde, imp
This commit is contained in:
Mike Barcroft 2002-04-01 07:58:26 +00:00
parent 7ca37d5578
commit 3d7dd7e8b8
1 changed files with 90 additions and 0 deletions
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90
sys/sys/cdefs.h
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@ -268,4 +268,94 @@
#define __DEQUALIFY(type, var) ((type)(uintptr_t)(const volatile void *)(var))
#endif
/*-
* The following definitions are an extension of the behavior originally
* implemented in <sys/_posix.h>, but with a different level of grandularity.
* POSIX.1 requires that the macros we test be defined before any standard
* header file is included.
*
* Here's a quick run-down of the versions:
* defined(_POSIX_SOURCE) 1003.1-1988
* _POSIX_C_SOURCE == 1 1003.1-1990
* _POSIX_C_SOURCE == 199309 1003.1b-1993
* _POSIX_C_SOURCE == 199506 1003.1c-1995, 1003.1i-1995,
* and the omnibus ISO/IEC 9945-1: 1996
* _POSIX_C_SOURCE == 200112 1003.1-2001
*
* In addition, the X/Open Portability Guide, which is now the Single UNIX
* Specification, defines a feature-test macro which indicates the version of
* that specification, and which subsumes _POSIX_C_SOURCE.
*
* Our macros begin with two underscores to avoid namespace screwage.
*/
/* Deal with IEEE Std. 1003.1-1990, in which _POSIX_C_SOURCE == 1. */
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE < 199309
#undef _POSIX_C_SOURCE /* Probably illegal, but beyond caring now. */
#define _POSIX_C_SOURCE 199009
#endif
/* Deal with various X/Open Portability Guides and Single UNIX Spec. */
#ifdef _XOPEN_SOURCE
#if _XOPEN_SOURCE >= 600
#define __XSI_VISIBLE 600
#undef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200112
#elif _XOPEN_SOURCE >= 500
#define __XSI_VISIBLE 500
#undef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 199506
#endif
#endif
/*
* Deal with all versions of POSIX. The ordering relative to the tests above is
* important.
*/
#if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE)
#define _POSIX_C_SOURCE 198808
#endif
#ifdef _POSIX_C_SOURCE
#if _POSIX_C_SOURCE >= 200112
#define __POSIX_VISIBLE 200112
#define __ISO_C_VISIBLE 1999
#elif _POSIX_C_SOURCE >= 199506
#define __POSIX_VISIBLE 199506
#define __ISO_C_VISIBLE 1990
#elif _POSIX_C_SOURCE >= 199309
#define __POSIX_VISIBLE 199309
#define __ISO_C_VISIBLE 1990
#elif _POSIX_C_SOURCE >= 199009
#define __POSIX_VISIBLE 199009
#define __ISO_C_VISIBLE 1990
#else
#define __POSIX_VISIBLE 198808
#define __ISO_C_VISIBLE 0
#endif /* _POSIX_C_SOURCE */
#else
/*-
* Deal with _ANSI_SOURCE:
* If it is defined, and no other compilation environment is explicitly
* requested, then define our internal feature-test macros to zero. This
* makes no difference to the preprocessor (undefined symbols in preprocessing
* expressions are defined to have value zero), but makes it more convenient for
* a test program to print out the values.
*
* If a program mistakenly defines _ANSI_SOURCE and some other macro such as
* _POSIX_C_SOURCE, we will assume that it wants the broader compilation
* environment (and in fact we will never get here).
*/
#ifdef _ANSI_SOURCE /* Hide almost everything. */
#define __POSIX_VISIBLE 0
#define __XSI_VISIBLE 0
#define __BSD_VISIBLE 0
#define __ISO_C_VISIBLE 1990
#else /* Default environment: show everything. */
#define __POSIX_VISIBLE 200112
#define __XSI_VISIBLE 600
#define __BSD_VISIBLE 1
#define __ISO_C_VISIBLE 1999
#endif
#endif
#endif /* !_SYS_CDEFS_H_ */