blob: c140620dad921a12bc36ac477911e12665d9a736 [file] [log] [blame]
Carlos O'Donellcfd280c2013-08-15 17:28:10 +08001/*
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. */
59#define __UAPI_DEF_IN6_ADDR 0
60/* The exception is the in6_addr macros which must be defined
61 * if the glibc code didn't define them. This guard matches
62 * the guard in glibc/inet/netinet/in.h which defines the
63 * additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
64#if defined(__USE_MISC) || defined (__USE_GNU)
65#define __UAPI_DEF_IN6_ADDR_ALT 0
66#else
67#define __UAPI_DEF_IN6_ADDR_ALT 1
68#endif
69#define __UAPI_DEF_SOCKADDR_IN6 0
70#define __UAPI_DEF_IPV6_MREQ 0
71#define __UAPI_DEF_IPPROTO_V6 0
72
73#else
74
75/* Linux headers included first, and we must define everything
76 * we need. The expectation is that glibc will check the
77 * __UAPI_DEF_* defines and adjust appropriately. */
78#define __UAPI_DEF_IN6_ADDR 1
79/* We unconditionally define the in6_addr macros and glibc must
80 * coordinate. */
81#define __UAPI_DEF_IN6_ADDR_ALT 1
82#define __UAPI_DEF_SOCKADDR_IN6 1
83#define __UAPI_DEF_IPV6_MREQ 1
84#define __UAPI_DEF_IPPROTO_V6 1
85
86#endif /* _NETINET_IN_H */
87
Serge Hallynea1a8212014-04-03 14:48:33 -070088/* Definitions for xattr.h */
89#if defined(_SYS_XATTR_H)
90#define __UAPI_DEF_XATTR 0
91#else
92#define __UAPI_DEF_XATTR 1
93#endif
Carlos O'Donellcfd280c2013-08-15 17:28:10 +080094
95/* If we did not see any headers from any supported C libraries,
96 * or we are being included in the kernel, then define everything
97 * that we need. */
98#else /* !defined(__GLIBC__) */
99
100/* Definitions for in6.h */
101#define __UAPI_DEF_IN6_ADDR 1
102#define __UAPI_DEF_IN6_ADDR_ALT 1
103#define __UAPI_DEF_SOCKADDR_IN6 1
104#define __UAPI_DEF_IPV6_MREQ 1
105#define __UAPI_DEF_IPPROTO_V6 1
106
Serge Hallynea1a8212014-04-03 14:48:33 -0700107/* Definitions for xattr.h */
108#define __UAPI_DEF_XATTR 1
109
Carlos O'Donellcfd280c2013-08-15 17:28:10 +0800110#endif /* __GLIBC__ */
111
112#endif /* _UAPI_LIBC_COMPAT_H */