[linux.git] / include / uapi / linux / libc-compat.h

/*
 * Compatibility interface for userspace libc header coordination:
 *
 * Define compatibility macros that are used to control the inclusion or
 * exclusion of UAPI structures and definitions in coordination with another
 * userspace C library.
 *
 * This header is intended to solve the problem of UAPI definitions that
 * conflict with userspace definitions. If a UAPI header has such conflicting
 * definitions then the solution is as follows:
 *
 * * Synchronize the UAPI header and the libc headers so either one can be
 *   used and such that the ABI is preserved. If this is not possible then
 *   no simple compatibility interface exists (you need to write translating
 *   wrappers and rename things) and you can't use this interface.
 *
 * Then follow this process:
 *
 * (a) Include libc-compat.h in the UAPI header.
 *      e.g. #include <linux/libc-compat.h>
 *     This include must be as early as possible.
 *
 * (b) In libc-compat.h add enough code to detect that the comflicting
 *     userspace libc header has been included first.
 *
 * (c) If the userspace libc header has been included first define a set of
 *     guard macros of the form __UAPI_DEF_FOO and set their values to 1, else
 *     set their values to 0.
 *
 * (d) Back in the UAPI header with the conflicting definitions, guard the
 *     definitions with:
 *     #if __UAPI_DEF_FOO
 *       ...
 *     #endif
 *
 * This fixes the situation where the linux headers are included *after* the
 * libc headers. To fix the problem with the inclusion in the other order the
 * userspace libc headers must be fixed like this:
 *
 * * For all definitions that conflict with kernel definitions wrap those
 *   defines in the following:
 *   #if !__UAPI_DEF_FOO
 *     ...
 *   #endif
 *
 * This prevents the redefinition of a construct already defined by the kernel.
 */
#ifndef _UAPI_LIBC_COMPAT_H
#define _UAPI_LIBC_COMPAT_H

/* We have included glibc headers... */
#if defined(__GLIBC__)

/* Coordinate with glibc netinet/in.h header. */
#if defined(_NETINET_IN_H)

/* GLIBC headers included first so don't define anything
 * that would already be defined. */
#define __UAPI_DEF_IN_ADDR		0
#define __UAPI_DEF_IN_IPPROTO		0
#define __UAPI_DEF_IN_PKTINFO		0
#define __UAPI_DEF_IP_MREQ		0
#define __UAPI_DEF_SOCKADDR_IN		0
#define __UAPI_DEF_IN_CLASS		0

#define __UAPI_DEF_IN6_ADDR		0
/* The exception is the in6_addr macros which must be defined
 * if the glibc code didn't define them. This guard matches
 * the guard in glibc/inet/netinet/in.h which defines the
 * additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
#if defined(__USE_MISC) || defined (__USE_GNU)
#define __UAPI_DEF_IN6_ADDR_ALT		0
#else
#define __UAPI_DEF_IN6_ADDR_ALT		1
#endif
#define __UAPI_DEF_SOCKADDR_IN6		0
#define __UAPI_DEF_IPV6_MREQ		0
#define __UAPI_DEF_IPPROTO_V6		0
#define __UAPI_DEF_IPV6_OPTIONS		0
#define __UAPI_DEF_IN6_PKTINFO		0
#define __UAPI_DEF_IP6_MTUINFO		0

#else

/* Linux headers included first, and we must define everything
 * we need. The expectation is that glibc will check the
 * __UAPI_DEF_* defines and adjust appropriately. */
#define __UAPI_DEF_IN_ADDR		1
#define __UAPI_DEF_IN_IPPROTO		1
#define __UAPI_DEF_IN_PKTINFO		1
#define __UAPI_DEF_IP_MREQ		1
#define __UAPI_DEF_SOCKADDR_IN		1
#define __UAPI_DEF_IN_CLASS		1

#define __UAPI_DEF_IN6_ADDR		1
/* We unconditionally define the in6_addr macros and glibc must
 * coordinate. */
#define __UAPI_DEF_IN6_ADDR_ALT		1
#define __UAPI_DEF_SOCKADDR_IN6		1
#define __UAPI_DEF_IPV6_MREQ		1
#define __UAPI_DEF_IPPROTO_V6		1
#define __UAPI_DEF_IPV6_OPTIONS		1
#define __UAPI_DEF_IN6_PKTINFO		1
#define __UAPI_DEF_IP6_MTUINFO		1

#endif /* _NETINET_IN_H */

/* Definitions for xattr.h */
#if defined(_SYS_XATTR_H)
#define __UAPI_DEF_XATTR		0
#else
#define __UAPI_DEF_XATTR		1
#endif

/* If we did not see any headers from any supported C libraries,
 * or we are being included in the kernel, then define everything
 * that we need. */
#else /* !defined(__GLIBC__) */

/* Definitions for in.h */
#define __UAPI_DEF_IN_ADDR		1
#define __UAPI_DEF_IN_IPPROTO		1
#define __UAPI_DEF_IN_PKTINFO		1
#define __UAPI_DEF_IP_MREQ		1
#define __UAPI_DEF_SOCKADDR_IN		1
#define __UAPI_DEF_IN_CLASS		1

/* Definitions for in6.h */
#define __UAPI_DEF_IN6_ADDR		1
#define __UAPI_DEF_IN6_ADDR_ALT		1
#define __UAPI_DEF_SOCKADDR_IN6		1
#define __UAPI_DEF_IPV6_MREQ		1
#define __UAPI_DEF_IPPROTO_V6		1
#define __UAPI_DEF_IPV6_OPTIONS		1
#define __UAPI_DEF_IN6_PKTINFO		1
#define __UAPI_DEF_IP6_MTUINFO		1

/* Definitions for xattr.h */
#define __UAPI_DEF_XATTR		1

#endif /* __GLIBC__ */

#endif /* _UAPI_LIBC_COMPAT_H */
Commit	Line	Data
cfd280c9 CD	1	/*
	2	* Compatibility interface for userspace libc header coordination:
	3	*
	4	* Define compatibility macros that are used to control the inclusion or
	5	* exclusion of UAPI structures and definitions in coordination with another
	6	* userspace C library.
	7	*
	8	* This header is intended to solve the problem of UAPI definitions that
	9	* conflict with userspace definitions. If a UAPI header has such conflicting
	10	* definitions then the solution is as follows:
	11	*
	12	* * Synchronize the UAPI header and the libc headers so either one can be
	13	* used and such that the ABI is preserved. If this is not possible then
	14	* no simple compatibility interface exists (you need to write translating
	15	* wrappers and rename things) and you can't use this interface.
	16	*
	17	* Then follow this process:
	18	*
	19	* (a) Include libc-compat.h in the UAPI header.
	20	* e.g. #include <linux/libc-compat.h>
	21	* This include must be as early as possible.
	22	*
	23	* (b) In libc-compat.h add enough code to detect that the comflicting
	24	* userspace libc header has been included first.
	25	*
	26	* (c) If the userspace libc header has been included first define a set of
	27	* guard macros of the form __UAPI_DEF_FOO and set their values to 1, else
	28	* set their values to 0.
	29	*
	30	* (d) Back in the UAPI header with the conflicting definitions, guard the
	31	* definitions with:
	32	* #if __UAPI_DEF_FOO
	33	* ...
	34	* #endif
	35	*
	36	* This fixes the situation where the linux headers are included after the
	37	* libc headers. To fix the problem with the inclusion in the other order the
	38	* userspace libc headers must be fixed like this:
	39	*
	40	* * For all definitions that conflict with kernel definitions wrap those
	41	* defines in the following:
	42	* #if !__UAPI_DEF_FOO
	43	* ...
	44	* #endif
	45	*
	46	* This prevents the redefinition of a construct already defined by the kernel.
	47	*/
	48	#ifndef _UAPI_LIBC_COMPAT_H
	49	#define _UAPI_LIBC_COMPAT_H
	50
	51	/* We have included glibc headers... */
	52	#if defined(__GLIBC__)
	53
	54	/* Coordinate with glibc netinet/in.h header. */
	55	#if defined(_NETINET_IN_H)
	56
	57	/* GLIBC headers included first so don't define anything
	58	* that would already be defined. */
279c6c7f SH	59	#define __UAPI_DEF_IN_ADDR 0
	60	#define __UAPI_DEF_IN_IPPROTO 0
	61	#define __UAPI_DEF_IN_PKTINFO 0
	62	#define __UAPI_DEF_IP_MREQ 0
	63	#define __UAPI_DEF_SOCKADDR_IN 0
	64	#define __UAPI_DEF_IN_CLASS 0
	65
cfd280c9 CD	66	#define __UAPI_DEF_IN6_ADDR 0
	67	/* The exception is the in6_addr macros which must be defined
	68	* if the glibc code didn't define them. This guard matches
	69	* the guard in glibc/inet/netinet/in.h which defines the
	70	* additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
	71	#if defined(__USE_MISC) \|\| defined (__USE_GNU)
	72	#define __UAPI_DEF_IN6_ADDR_ALT 0
	73	#else
	74	#define __UAPI_DEF_IN6_ADDR_ALT 1
	75	#endif
	76	#define __UAPI_DEF_SOCKADDR_IN6 0
	77	#define __UAPI_DEF_IPV6_MREQ 0
	78	#define __UAPI_DEF_IPPROTO_V6 0
6d08acd2	79	#define __UAPI_DEF_IPV6_OPTIONS 0
3b50d902 WC	80	#define __UAPI_DEF_IN6_PKTINFO 0
3b50d902 WC	81	#define __UAPI_DEF_IP6_MTUINFO 0
cfd280c9 CD	82
	83	#else
	84
	85	/* Linux headers included first, and we must define everything
	86	* we need. The expectation is that glibc will check the
	87	* __UAPI_DEF_* defines and adjust appropriately. */
279c6c7f SH	88	#define __UAPI_DEF_IN_ADDR 1
	89	#define __UAPI_DEF_IN_IPPROTO 1
	90	#define __UAPI_DEF_IN_PKTINFO 1
	91	#define __UAPI_DEF_IP_MREQ 1
	92	#define __UAPI_DEF_SOCKADDR_IN 1
	93	#define __UAPI_DEF_IN_CLASS 1
	94
cfd280c9 CD	95	#define __UAPI_DEF_IN6_ADDR 1
	96	/* We unconditionally define the in6_addr macros and glibc must
	97	* coordinate. */
	98	#define __UAPI_DEF_IN6_ADDR_ALT 1
	99	#define __UAPI_DEF_SOCKADDR_IN6 1
	100	#define __UAPI_DEF_IPV6_MREQ 1
	101	#define __UAPI_DEF_IPPROTO_V6 1
6d08acd2	102	#define __UAPI_DEF_IPV6_OPTIONS 1
3b50d902 WC	103	#define __UAPI_DEF_IN6_PKTINFO 1
3b50d902 WC	104	#define __UAPI_DEF_IP6_MTUINFO 1
cfd280c9 CD	105
	106	#endif /* _NETINET_IN_H */
	107
ea1a8217 SH	108	/* Definitions for xattr.h */
	109	#if defined(_SYS_XATTR_H)
	110	#define __UAPI_DEF_XATTR 0
	111	#else
	112	#define __UAPI_DEF_XATTR 1
	113	#endif
cfd280c9 CD	114
	115	/* If we did not see any headers from any supported C libraries,
	116	* or we are being included in the kernel, then define everything
	117	* that we need. */
	118	#else /* !defined(__GLIBC__) */
	119
279c6c7f SH	120	/* Definitions for in.h */
	121	#define __UAPI_DEF_IN_ADDR 1
	122	#define __UAPI_DEF_IN_IPPROTO 1
	123	#define __UAPI_DEF_IN_PKTINFO 1
	124	#define __UAPI_DEF_IP_MREQ 1
	125	#define __UAPI_DEF_SOCKADDR_IN 1
	126	#define __UAPI_DEF_IN_CLASS 1
	127
cfd280c9 CD	128	/* Definitions for in6.h */
	129	#define __UAPI_DEF_IN6_ADDR 1
	130	#define __UAPI_DEF_IN6_ADDR_ALT 1
	131	#define __UAPI_DEF_SOCKADDR_IN6 1
	132	#define __UAPI_DEF_IPV6_MREQ 1
	133	#define __UAPI_DEF_IPPROTO_V6 1
6d08acd2	134	#define __UAPI_DEF_IPV6_OPTIONS 1
3b50d902 WC	135	#define __UAPI_DEF_IN6_PKTINFO 1
3b50d902 WC	136	#define __UAPI_DEF_IP6_MTUINFO 1
cfd280c9	137
ea1a8217 SH	138	/* Definitions for xattr.h */
	139	#define __UAPI_DEF_XATTR 1
	140
cfd280c9 CD	141	#endif /* __GLIBC__ */
	142
	143	#endif /* _UAPI_LIBC_COMPAT_H */