linux: For better compatibility, provide compatible endian.h
Add endian.h. This includes sys/endian.h and then adds extra defines
that glibc defines with double underscores for our
_{BIG,BYTE,LITTLE,PDP}_ENDIAN macros. We also define __FLOAT_WORD_ORDER
to be the same as _BYTE_ENDIAN since FreeBSD doesn't currently define
this, and the default with glibc is exactly this for our platforms.
Move common parts of endian.h and sys/endian.h into sys/_endian.h
to limit namespace pollution from endian.h
All this gives us good compatibility with Linux. There may be one or two
upstreams that haven't integrated the patches I tried to send up.
There are some minor differences:
o The extra glibc macros are not defined. These are all
controlled with either __ at the start, or only defined
when glibc is being built. We also don't define macros
that are used internally in glibc that would pollute
the namespace.
o For complete compatibility, this change must also be
paired with providing a glibc-compatible byteswap.h.
Sponsored by: Netflix
Reviewed by: mhorne, markj, jhb
Differential Revision: https://reviews.freebsd.org/D31962
This commit is contained in:
Warner Losh
parent
e8c1bd7257
commit
30e0d2a510
@ -14,8 +14,8 @@ SUBDIR+= i386
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SUBDIR_PARALLEL=
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INCS= a.out.h ar.h assert.h bitstring.h complex.h cpio.h _ctype.h ctype.h \
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db.h \
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dirent.h dlfcn.h elf.h elf-hints.h err.h fmtmsg.h fnmatch.h fstab.h \
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fts.h ftw.h getopt.h glob.h grp.h \
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dirent.h dlfcn.h elf.h elf-hints.h endian.h err.h fmtmsg.h fnmatch.h \
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fstab.h fts.h ftw.h getopt.h glob.h grp.h \
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ieeefp.h ifaddrs.h \
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inttypes.h iso646.h kenv.h langinfo.h libgen.h limits.h link.h \
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locale.h malloc.h malloc_np.h memory.h monetary.h mpool.h mqueue.h \
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43
include/endian.h
Normal file
43
include/endian.h
Normal file
@ -0,0 +1,43 @@
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/*-
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* Copyright (c) 2021 M. Warner Losh <imp@FreeBSD.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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/*
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* A mostly Linux/glibc-compatible endian.h
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*/
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#ifndef _ENDIAN_H_
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#define _ENDIAN_H_
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/*
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* FreeBSD's sys/_endian.h is very close to the interface provided on Linux by
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* glibc's endian.h.
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*/
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#include <sys/_endian.h>
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/*
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* glibc uses double underscore for these symbols. Define these unconditionally.
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* The compiler defines __BYTE_ORDER__ these days, so we don't do anything
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* with that since sys/endian.h defines _BYTE_ORDER based on it.
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*/
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#define __BIG_ENDIAN _BIG_ENDIAN
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#define __BYTE_ORDER _BYTE_ORDER
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#define __LITTLE_ENDIAN _LITTLE_ENDIAN
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#define __PDP_ENDIAN _PDP_ENDIAN
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/*
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* FreeBSD's sys/endian.h and machine/endian.h doesn't define a separate
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* byte order for floats. Use the host non-float byte order.
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*/
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#define __FLOAT_WORD_ORDER _BYTE_ORDER
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/*
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* We don't define BIG_ENDI, LITTLE_ENDI, HIGH_HALF and LOW_HALF macros that
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* glibc's endian.h defines since those appear to be internal to internal to
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* glibc. We also don't try to emulate the various helper macros that glibc
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* uses to limit namespace visibility.
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*/
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#endif /* _ENDIAN_H_ */
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@ -32,7 +32,7 @@
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#ifndef _SYS__ENDIAN_H_
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#define _SYS__ENDIAN_H_
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#ifndef _MACHINE_ENDIAN_H_
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#if !defined(_MACHINE_ENDIAN_H_) && !defined(_ENDIAN_H_)
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#error "sys/_endian.h should not be included directly"
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#endif
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@ -89,4 +89,38 @@
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#define __ntohs(x) ((__uint16_t)(x))
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#endif
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/*
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* Host to big endian, host to little endian, big endian to host, and little
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* endian to host byte order functions as detailed in byteorder(9).
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*/
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#if _BYTE_ORDER == _LITTLE_ENDIAN
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#define htobe16(x) __bswap16((x))
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#define htobe32(x) __bswap32((x))
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#define htobe64(x) __bswap64((x))
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#define htole16(x) ((uint16_t)(x))
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#define htole32(x) ((uint32_t)(x))
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#define htole64(x) ((uint64_t)(x))
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#define be16toh(x) __bswap16((x))
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#define be32toh(x) __bswap32((x))
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#define be64toh(x) __bswap64((x))
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#define le16toh(x) ((uint16_t)(x))
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#define le32toh(x) ((uint32_t)(x))
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#define le64toh(x) ((uint64_t)(x))
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#else /* _BYTE_ORDER != _LITTLE_ENDIAN */
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#define htobe16(x) ((uint16_t)(x))
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#define htobe32(x) ((uint32_t)(x))
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#define htobe64(x) ((uint64_t)(x))
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#define htole16(x) __bswap16((x))
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#define htole32(x) __bswap32((x))
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#define htole64(x) __bswap64((x))
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#define be16toh(x) ((uint16_t)(x))
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#define be32toh(x) ((uint32_t)(x))
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#define be64toh(x) ((uint64_t)(x))
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#define le16toh(x) __bswap16((x))
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#define le32toh(x) __bswap32((x))
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#define le64toh(x) __bswap64((x))
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#endif /* _BYTE_ORDER == _LITTLE_ENDIAN */
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#endif /* _SYS__ENDIAN_H_ */
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@ -55,6 +55,12 @@ typedef __uint64_t uint64_t;
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#define _UINT64_T_DECLARED
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#endif
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/*
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* Note: While tempting to try to avoid namespace pollution from this file,
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* several software packages assume these marcos are defined, even when it
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* defines _POSIX_C_SOURCE to request an unpolluted namespace.
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*/
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/*
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* General byte order swapping functions.
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*/
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@ -62,42 +68,7 @@ typedef __uint64_t uint64_t;
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#define bswap32(x) __bswap32(x)
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#define bswap64(x) __bswap64(x)
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/*
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* Host to big endian, host to little endian, big endian to host, and little
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* endian to host byte order functions as detailed in byteorder(9).
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*/
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#if _BYTE_ORDER == _LITTLE_ENDIAN
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#define htobe16(x) __bswap16((x))
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#define htobe32(x) __bswap32((x))
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#define htobe64(x) __bswap64((x))
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#define htole16(x) ((uint16_t)(x))
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#define htole32(x) ((uint32_t)(x))
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#define htole64(x) ((uint64_t)(x))
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#define be16toh(x) __bswap16((x))
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#define be32toh(x) __bswap32((x))
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#define be64toh(x) __bswap64((x))
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#define le16toh(x) ((uint16_t)(x))
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#define le32toh(x) ((uint32_t)(x))
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#define le64toh(x) ((uint64_t)(x))
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#else /* _BYTE_ORDER != _LITTLE_ENDIAN */
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#define htobe16(x) ((uint16_t)(x))
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#define htobe32(x) ((uint32_t)(x))
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#define htobe64(x) ((uint64_t)(x))
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#define htole16(x) __bswap16((x))
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#define htole32(x) __bswap32((x))
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#define htole64(x) __bswap64((x))
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#define be16toh(x) ((uint16_t)(x))
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#define be32toh(x) ((uint32_t)(x))
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#define be64toh(x) ((uint64_t)(x))
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#define le16toh(x) __bswap16((x))
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#define le32toh(x) __bswap32((x))
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#define le64toh(x) __bswap64((x))
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#endif /* _BYTE_ORDER == _LITTLE_ENDIAN */
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/* Alignment-agnostic encode/decode bytestream to/from little/big endian. */
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static __inline uint16_t
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be16dec(const void *pp)
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{
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@ -203,5 +174,4 @@ le64enc(void *pp, uint64_t u)
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le32enc(p, (uint32_t)(u & 0xffffffffU));
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le32enc(p + 4, (uint32_t)(u >> 32));
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}
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#endif /* _SYS_ENDIAN_H_ */
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