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