/* $OpenBSD: namespace.h,v 1.3 2018/03/12 06:19:19 guenther Exp $ */ #ifndef _LIBM_NAMESPACE_H_ #define _LIBM_NAMESPACE_H_ /* * Copyright (c) 2015 Philip Guenther <guenther@openbsd.org> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* * The goal: calls from inside libc to other libc functions should be via * identifiers that are of hidden visibility and--to avoid confusion--are * in the reserved namespace. By doing this these calls are protected * from overriding by applications and on many platforms can avoid creation * or use of GOT or PLT entries. I've chosen a prefix of "_libm_" for this. * These will not be declared directly; instead, the gcc "asm labels" * extension will be used rename the function. * * In order to actually set up the desired asm labels, we use these in * the internal .h files: * PROTO_NORMAL(x) Symbols used both internally and externally * This makes gcc convert use of x to use _libm_x instead. Use * DEF_STD(x) or DEF_NONSTD(x) to create the external alias. * ex: PROTO_NORMAL(ceil) * * PROTO_STD_DEPRECATED(x) Standard C symbols that are not used internally * This just marks the symbol as deprecated, with no renaming. * Do not use DEF_*(x) with this. * ex: PROTO_STD_DEPRECATED(tgammal) * * PROTO_DEPRECATED(x) Symbols not in C that are not used internally * This marks the symbol as deprecated and, in the static lib, weak. * No renaming is done. Do not use DEF_*(x) with this. * ex: PROTO_DEPRECATED(creat) * * Finally, to create the expected aliases, we use these in the .c files * where the definitions are: * DEF_STD(x) Symbols reserved to or specified by ISO C * This defines x as a strong alias for _libm_x; this must only * be used for symbols that are reserved by the C standard * (or reserved in the external identifier namespace). * Matches with PROTO_NORMAL() * ex: DEF_STD(fopen) * * DEF_NONSTD(x) Symbols used internally and not in ISO C * This defines x as a alias for _libm_x, weak in the static version * Matches with PROTO_NORMAL() * ex: DEF_NONSTD(lseek) * * LDBL_CLONE(x) long double aliases that are used * This defines xl and _libm_xl as aliases for _libm_x. * Matches with LDBL_PROTO_NORMAL() * * LDBL_UNUSED_CLONE(x) long double aliases that are unused * This defines xl as an alias for _libm_x. * Matches with LDBL_PROTO_STD_DEPRECATED() * * LDBL_MAYBE_CLONE(x) * LDBL_MAYBE_UNUSED_CLONE(x) * Like LDBL_CLONE() and LDBL_UNUSED_CLONE(), except they do nothing * if LDBL_MANT_DIG != DBL_MANT_DIG * * MAKE_UNUSED_CLONE(dst, src) Unused symbols that are exact clones * of other symbols * This declares dst as being the same type as dst, and makes * _libm_dst a strong, hidden alias for _libm_src. You still need to * DEF_STD(dst) or DEF_NONSTD(dst) to alias dst itself * ex: MAKE_UNUSED_CLONE(nexttoward, nextafter); */ #include <sys/cdefs.h> /* for __dso_hidden and __{weak,strong}_alias */ #ifndef PIC # define WEAK_IN_STATIC_ALIAS(x,y) __weak_alias(x,y) # define WEAK_IN_STATIC __attribute__((weak)) #else # define WEAK_IN_STATIC_ALIAS(x,y) __strong_alias(x,y) # define WEAK_IN_STATIC /* nothing */ #endif #define HIDDEN(x) _libm_##x #define HIDDEN_STRING(x) "_libm_" __STRING(x) #define PROTO_NORMAL(x) __dso_hidden typeof(x) HIDDEN(x), x asm(HIDDEN_STRING(x)) #define PROTO_STD_DEPRECATED(x) typeof(x) HIDDEN(x), x __attribute__((deprecated)) #define PROTO_DEPRECATED(x) PROTO_STD_DEPRECATED(x) WEAK_IN_STATIC #define DEF_STD(x) __strong_alias(x, HIDDEN(x)) #define DEF_NONSTD(x) WEAK_IN_STATIC_ALIAS(x, HIDDEN(x)) #define MAKE_UNUSED_CLONE(dst, src) __strong_alias(dst, src) #define LDBL_UNUSED_CLONE(x) __strong_alias(x##l, HIDDEN(x)) #define LDBL_NONSTD_UNUSED_CLONE(x) WEAK_IN_STATIC_ALIAS(x##l, HIDDEN(x)) #define LDBL_CLONE(x) LDBL_UNUSED_CLONE(x); \ __dso_hidden typeof(HIDDEN(x##l)) HIDDEN(x##l) \ __attribute__((alias (HIDDEN_STRING(x)))) #define LDBL_NONSTD_CLONE(x) LDBL_NONSTD_UNUSED_CLONE(x); \ __dso_hidden typeof(HIDDEN(x##l)) HIDDEN(x##l) \ __attribute__((alias (HIDDEN_STRING(x)))) #if __LDBL_MANT_DIG__ == __DBL_MANT_DIG__ # define LDBL_PROTO_NORMAL(x) typeof(x) HIDDEN(x) # define LDBL_PROTO_STD_DEPRECATED(x) typeof(x) HIDDEN(x) # define LDBL_MAYBE_CLONE(x) LDBL_CLONE(x) # define LDBL_MAYBE_UNUSED_CLONE(x) LDBL_UNUSED_CLONE(x) # define LDBL_MAYBE_NONSTD_UNUSED_CLONE(x) LDBL_NONSTD_UNUSED_CLONE(x) # define LDBL_MAYBE_NONSTD_CLONE(x) LDBL_NONSTD_CLONE(x) #else # define LDBL_PROTO_NORMAL(x) PROTO_NORMAL(x) # define LDBL_PROTO_STD_DEPRECATED(x) PROTO_STD_DEPRECATED(x) # define LDBL_MAYBE_CLONE(x) __asm("") # define LDBL_MAYBE_UNUSED_CLONE(x) __asm("") # define LDBL_MAYBE_NONSTD_UNUSED_CLONE(x) __asm("") # define LDBL_MAYBE_NONSTD_CLONE(x) __asm("") #endif #endif /* _LIBM_NAMESPACE_H_ */
