linux-headers (unknown)
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 _LIBC_COMPAT_H
50 #define _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 /* _LIBC_COMPAT_H */
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