1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2/*
3 * Compatibility interface for userspace libc header coordination:
4 *
5 * Define compatibility macros that are used to control the inclusion or
6 * exclusion of UAPI structures and definitions in coordination with another
7 * userspace C library.
8 *
9 * This header is intended to solve the problem of UAPI definitions that
10 * conflict with userspace definitions. If a UAPI header has such conflicting
11 * definitions then the solution is as follows:
12 *
13 * * Synchronize the UAPI header and the libc headers so either one can be
14 * used and such that the ABI is preserved. If this is not possible then
15 * no simple compatibility interface exists (you need to write translating
16 * wrappers and rename things) and you can't use this interface.
17 *
18 * Then follow this process:
19 *
20 * (a) Include libc-compat.h in the UAPI header.
21 * e.g. #include <linux/libc-compat.h>
22 * This include must be as early as possible.
23 *
24 * (b) In libc-compat.h add enough code to detect that the comflicting
25 * userspace libc header has been included first.
26 *
27 * (c) If the userspace libc header has been included first define a set of
28 * guard macros of the form __UAPI_DEF_FOO and set their values to 1, else
29 * set their values to 0.
30 *
31 * (d) Back in the UAPI header with the conflicting definitions, guard the
32 * definitions with:
33 * #if __UAPI_DEF_FOO
34 * ...
35 * #endif
36 *
37 * This fixes the situation where the linux headers are included *after* the
38 * libc headers. To fix the problem with the inclusion in the other order the
39 * userspace libc headers must be fixed like this:
40 *
41 * * For all definitions that conflict with kernel definitions wrap those
42 * defines in the following:
43 * #if !__UAPI_DEF_FOO
44 * ...
45 * #endif
46 *
47 * This prevents the redefinition of a construct already defined by the kernel.
48 */
49#ifndef _UAPI_LIBC_COMPAT_H
50#define _UAPI_LIBC_COMPAT_H
51
52/* We have included glibc headers... */
53#if defined(__GLIBC__)
54
55/* Coordinate with glibc net/if.h header. */
56#if defined(_NET_IF_H) && defined(__USE_MISC)
57
58/* GLIBC headers included first so don't define anything
59 * that would already be defined. */
60
61#define __UAPI_DEF_IF_IFCONF 0
62#define __UAPI_DEF_IF_IFMAP 0
63#define __UAPI_DEF_IF_IFNAMSIZ 0
64#define __UAPI_DEF_IF_IFREQ 0
65/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
66#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 0
67/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
68#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
69#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
70#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
71
72#else /* _NET_IF_H */
73
74/* Linux headers included first, and we must define everything
75 * we need. The expectation is that glibc will check the
76 * __UAPI_DEF_* defines and adjust appropriately. */
77
78#define __UAPI_DEF_IF_IFCONF 1
79#define __UAPI_DEF_IF_IFMAP 1
80#define __UAPI_DEF_IF_IFNAMSIZ 1
81#define __UAPI_DEF_IF_IFREQ 1
82/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
83#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
84/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
85#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
86
87#endif /* _NET_IF_H */
88
89/* Coordinate with glibc netinet/in.h header. */
90#if defined(_NETINET_IN_H)
91
92/* GLIBC headers included first so don't define anything
93 * that would already be defined. */
94#define __UAPI_DEF_IN_ADDR 0
95#define __UAPI_DEF_IN_IPPROTO 0
96#define __UAPI_DEF_IN_PKTINFO 0
97#define __UAPI_DEF_IP_MREQ 0
98#define __UAPI_DEF_SOCKADDR_IN 0
99#define __UAPI_DEF_IN_CLASS 0
100
101#define __UAPI_DEF_IN6_ADDR 0
102/* The exception is the in6_addr macros which must be defined
103 * if the glibc code didn't define them. This guard matches
104 * the guard in glibc/inet/netinet/in.h which defines the
105 * additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
106#if defined(__USE_MISC) || defined (__USE_GNU)
107#define __UAPI_DEF_IN6_ADDR_ALT 0
108#else
109#define __UAPI_DEF_IN6_ADDR_ALT 1
110#endif
111#define __UAPI_DEF_SOCKADDR_IN6 0
112#define __UAPI_DEF_IPV6_MREQ 0
113#define __UAPI_DEF_IPPROTO_V6 0
114#define __UAPI_DEF_IPV6_OPTIONS 0
115#define __UAPI_DEF_IN6_PKTINFO 0
116#define __UAPI_DEF_IP6_MTUINFO 0
117
118#else
119
120/* Linux headers included first, and we must define everything
121 * we need. The expectation is that glibc will check the
122 * __UAPI_DEF_* defines and adjust appropriately. */
123#define __UAPI_DEF_IN_ADDR 1
124#define __UAPI_DEF_IN_IPPROTO 1
125#define __UAPI_DEF_IN_PKTINFO 1
126#define __UAPI_DEF_IP_MREQ 1
127#define __UAPI_DEF_SOCKADDR_IN 1
128#define __UAPI_DEF_IN_CLASS 1
129
130#define __UAPI_DEF_IN6_ADDR 1
131/* We unconditionally define the in6_addr macros and glibc must
132 * coordinate. */
133#define __UAPI_DEF_IN6_ADDR_ALT 1
134#define __UAPI_DEF_SOCKADDR_IN6 1
135#define __UAPI_DEF_IPV6_MREQ 1
136#define __UAPI_DEF_IPPROTO_V6 1
137#define __UAPI_DEF_IPV6_OPTIONS 1
138#define __UAPI_DEF_IN6_PKTINFO 1
139#define __UAPI_DEF_IP6_MTUINFO 1
140
141#endif /* _NETINET_IN_H */
142
143/* Coordinate with glibc netipx/ipx.h header. */
144#if defined(__NETIPX_IPX_H)
145
146#define __UAPI_DEF_SOCKADDR_IPX 0
147#define __UAPI_DEF_IPX_ROUTE_DEFINITION 0
148#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 0
149#define __UAPI_DEF_IPX_CONFIG_DATA 0
150#define __UAPI_DEF_IPX_ROUTE_DEF 0
151
152#else /* defined(__NETIPX_IPX_H) */
153
154#define __UAPI_DEF_SOCKADDR_IPX 1
155#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
156#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
157#define __UAPI_DEF_IPX_CONFIG_DATA 1
158#define __UAPI_DEF_IPX_ROUTE_DEF 1
159
160#endif /* defined(__NETIPX_IPX_H) */
161
162/* Definitions for xattr.h */
163#if defined(_SYS_XATTR_H)
164#define __UAPI_DEF_XATTR 0
165#else
166#define __UAPI_DEF_XATTR 1
167#endif
168
169/* If we did not see any headers from any supported C libraries,
170 * or we are being included in the kernel, then define everything
171 * that we need. Check for previous __UAPI_* definitions to give
172 * unsupported C libraries a way to opt out of any kernel definition. */
173#else /* !defined(__GLIBC__) */
174
175/* Definitions for if.h */
176#ifndef __UAPI_DEF_IF_IFCONF
177#define __UAPI_DEF_IF_IFCONF 1
178#endif
179#ifndef __UAPI_DEF_IF_IFMAP
180#define __UAPI_DEF_IF_IFMAP 1
181#endif
182#ifndef __UAPI_DEF_IF_IFNAMSIZ
183#define __UAPI_DEF_IF_IFNAMSIZ 1
184#endif
185#ifndef __UAPI_DEF_IF_IFREQ
186#define __UAPI_DEF_IF_IFREQ 1
187#endif
188/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
189#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS
190#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
191#endif
192/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
193#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
194#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
195#endif
196
197/* Definitions for in.h */
198#ifndef __UAPI_DEF_IN_ADDR
199#define __UAPI_DEF_IN_ADDR 1
200#endif
201#ifndef __UAPI_DEF_IN_IPPROTO
202#define __UAPI_DEF_IN_IPPROTO 1
203#endif
204#ifndef __UAPI_DEF_IN_PKTINFO
205#define __UAPI_DEF_IN_PKTINFO 1
206#endif
207#ifndef __UAPI_DEF_IP_MREQ
208#define __UAPI_DEF_IP_MREQ 1
209#endif
210#ifndef __UAPI_DEF_SOCKADDR_IN
211#define __UAPI_DEF_SOCKADDR_IN 1
212#endif
213#ifndef __UAPI_DEF_IN_CLASS
214#define __UAPI_DEF_IN_CLASS 1
215#endif
216
217/* Definitions for in6.h */
218#ifndef __UAPI_DEF_IN6_ADDR
219#define __UAPI_DEF_IN6_ADDR 1
220#endif
221#ifndef __UAPI_DEF_IN6_ADDR_ALT
222#define __UAPI_DEF_IN6_ADDR_ALT 1
223#endif
224#ifndef __UAPI_DEF_SOCKADDR_IN6
225#define __UAPI_DEF_SOCKADDR_IN6 1
226#endif
227#ifndef __UAPI_DEF_IPV6_MREQ
228#define __UAPI_DEF_IPV6_MREQ 1
229#endif
230#ifndef __UAPI_DEF_IPPROTO_V6
231#define __UAPI_DEF_IPPROTO_V6 1
232#endif
233#ifndef __UAPI_DEF_IPV6_OPTIONS
234#define __UAPI_DEF_IPV6_OPTIONS 1
235#endif
236#ifndef __UAPI_DEF_IN6_PKTINFO
237#define __UAPI_DEF_IN6_PKTINFO 1
238#endif
239#ifndef __UAPI_DEF_IP6_MTUINFO
240#define __UAPI_DEF_IP6_MTUINFO 1
241#endif
242
243/* Definitions for ipx.h */
244#ifndef __UAPI_DEF_SOCKADDR_IPX
245#define __UAPI_DEF_SOCKADDR_IPX 1
246#endif
247#ifndef __UAPI_DEF_IPX_ROUTE_DEFINITION
248#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
249#endif
250#ifndef __UAPI_DEF_IPX_INTERFACE_DEFINITION
251#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
252#endif
253#ifndef __UAPI_DEF_IPX_CONFIG_DATA
254#define __UAPI_DEF_IPX_CONFIG_DATA 1
255#endif
256#ifndef __UAPI_DEF_IPX_ROUTE_DEF
257#define __UAPI_DEF_IPX_ROUTE_DEF 1
258#endif
259
260/* Definitions for xattr.h */
261#ifndef __UAPI_DEF_XATTR
262#define __UAPI_DEF_XATTR 1
263#endif
264
265#endif /* __GLIBC__ */
266
267#endif /* _UAPI_LIBC_COMPAT_H */
268