--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * 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 _LIBC_COMPAT_H
+#define _LIBC_COMPAT_H
+
+/* We have included glibc headers... */
+#if defined(__GLIBC__)
+
+/* Coordinate with glibc net/if.h header. */
+#if defined(_NET_IF_H) && defined(__USE_MISC)
+
+/* GLIBC headers included first so don't define anything
+ * that would already be defined. */
+
+#define __UAPI_DEF_IF_IFCONF 0
+#define __UAPI_DEF_IF_IFMAP 0
+#define __UAPI_DEF_IF_IFNAMSIZ 0
+#define __UAPI_DEF_IF_IFREQ 0
+/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 0
+/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
+#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
+#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
+
+#else /* _NET_IF_H */
+
+/* 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_IF_IFCONF 1
+#define __UAPI_DEF_IF_IFMAP 1
+#define __UAPI_DEF_IF_IFNAMSIZ 1
+#define __UAPI_DEF_IF_IFREQ 1
+/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
+/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
+
+#endif /* _NET_IF_H */
+
+/* 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 */
+
+/* Coordinate with glibc netipx/ipx.h header. */
+#if defined(__NETIPX_IPX_H)
+
+#define __UAPI_DEF_SOCKADDR_IPX 0
+#define __UAPI_DEF_IPX_ROUTE_DEFINITION 0
+#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 0
+#define __UAPI_DEF_IPX_CONFIG_DATA 0
+#define __UAPI_DEF_IPX_ROUTE_DEF 0
+
+#else /* defined(__NETIPX_IPX_H) */
+
+#define __UAPI_DEF_SOCKADDR_IPX 1
+#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
+#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
+#define __UAPI_DEF_IPX_CONFIG_DATA 1
+#define __UAPI_DEF_IPX_ROUTE_DEF 1
+
+#endif /* defined(__NETIPX_IPX_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. Check for previous __UAPI_* definitions to give
+ * unsupported C libraries a way to opt out of any kernel definition. */
+#else /* !defined(__GLIBC__) */
+
+/* Definitions for if.h */
+#ifndef __UAPI_DEF_IF_IFCONF
+#define __UAPI_DEF_IF_IFCONF 1
+#endif
+#ifndef __UAPI_DEF_IF_IFMAP
+#define __UAPI_DEF_IF_IFMAP 1
+#endif
+#ifndef __UAPI_DEF_IF_IFNAMSIZ
+#define __UAPI_DEF_IF_IFNAMSIZ 1
+#endif
+#ifndef __UAPI_DEF_IF_IFREQ
+#define __UAPI_DEF_IF_IFREQ 1
+#endif
+/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
+#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
+#endif
+/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
+#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
+#endif
+
+/* Definitions for in.h */
+#ifndef __UAPI_DEF_IN_ADDR
+#define __UAPI_DEF_IN_ADDR 1
+#endif
+#ifndef __UAPI_DEF_IN_IPPROTO
+#define __UAPI_DEF_IN_IPPROTO 1
+#endif
+#ifndef __UAPI_DEF_IN_PKTINFO
+#define __UAPI_DEF_IN_PKTINFO 1
+#endif
+#ifndef __UAPI_DEF_IP_MREQ
+#define __UAPI_DEF_IP_MREQ 1
+#endif
+#ifndef __UAPI_DEF_SOCKADDR_IN
+#define __UAPI_DEF_SOCKADDR_IN 1
+#endif
+#ifndef __UAPI_DEF_IN_CLASS
+#define __UAPI_DEF_IN_CLASS 1
+#endif
+
+/* Definitions for in6.h */
+#ifndef __UAPI_DEF_IN6_ADDR
+#define __UAPI_DEF_IN6_ADDR 1
+#endif
+#ifndef __UAPI_DEF_IN6_ADDR_ALT
+#define __UAPI_DEF_IN6_ADDR_ALT 1
+#endif
+#ifndef __UAPI_DEF_SOCKADDR_IN6
+#define __UAPI_DEF_SOCKADDR_IN6 1
+#endif
+#ifndef __UAPI_DEF_IPV6_MREQ
+#define __UAPI_DEF_IPV6_MREQ 1
+#endif
+#ifndef __UAPI_DEF_IPPROTO_V6
+#define __UAPI_DEF_IPPROTO_V6 1
+#endif
+#ifndef __UAPI_DEF_IPV6_OPTIONS
+#define __UAPI_DEF_IPV6_OPTIONS 1
+#endif
+#ifndef __UAPI_DEF_IN6_PKTINFO
+#define __UAPI_DEF_IN6_PKTINFO 1
+#endif
+#ifndef __UAPI_DEF_IP6_MTUINFO
+#define __UAPI_DEF_IP6_MTUINFO 1
+#endif
+
+/* Definitions for ipx.h */
+#ifndef __UAPI_DEF_SOCKADDR_IPX
+#define __UAPI_DEF_SOCKADDR_IPX 1
+#endif
+#ifndef __UAPI_DEF_IPX_ROUTE_DEFINITION
+#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
+#endif
+#ifndef __UAPI_DEF_IPX_INTERFACE_DEFINITION
+#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
+#endif
+#ifndef __UAPI_DEF_IPX_CONFIG_DATA
+#define __UAPI_DEF_IPX_CONFIG_DATA 1
+#endif
+#ifndef __UAPI_DEF_IPX_ROUTE_DEF
+#define __UAPI_DEF_IPX_ROUTE_DEF 1
+#endif
+
+/* Definitions for xattr.h */
+#ifndef __UAPI_DEF_XATTR
+#define __UAPI_DEF_XATTR 1
+#endif
+
+#endif /* __GLIBC__ */
+
+#endif /* _LIBC_COMPAT_H */
projects / cross.git / blobdiff