mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-09 04:11:27 +08:00
385 lines
14 KiB
C
385 lines
14 KiB
C
/* Support macros for making weak and strong aliases for symbols,
|
||
and for using symbol sets and linker warnings with GNU ld.
|
||
Copyright (C) 1995-1998,2000,2001,2002 Free Software Foundation, Inc.
|
||
This file is part of the GNU C Library.
|
||
|
||
The GNU C Library is free software; you can redistribute it and/or
|
||
modify it under the terms of the GNU Lesser General Public
|
||
License as published by the Free Software Foundation; either
|
||
version 2.1 of the License, or (at your option) any later version.
|
||
|
||
The GNU C Library is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public
|
||
License along with the GNU C Library; if not, write to the Free
|
||
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
||
02111-1307 USA. */
|
||
|
||
#ifndef _LIBC_SYMBOLS_H
|
||
#define _LIBC_SYMBOLS_H 1
|
||
|
||
/* This file's macros are included implicitly in the compilation of every
|
||
file in the C library by -imacros.
|
||
|
||
We include config.h which is generated by configure.
|
||
It should define for us the following symbols:
|
||
|
||
* HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
|
||
* ASM_GLOBAL_DIRECTIVE with `.globl' or `.global'.
|
||
* HAVE_GNU_LD if using GNU ld, with support for weak symbols in a.out,
|
||
and for symbol set and warning messages extensions in a.out and ELF.
|
||
* HAVE_ELF if using ELF, which supports weak symbols using `.weak'.
|
||
* HAVE_ASM_WEAK_DIRECTIVE if we have weak symbols using `.weak'.
|
||
* HAVE_ASM_WEAKEXT_DIRECTIVE if we have weak symbols using `.weakext'.
|
||
|
||
*/
|
||
|
||
/* This is defined for the compilation of all C library code. features.h
|
||
tests this to avoid inclusion of stubs.h while compiling the library,
|
||
before stubs.h has been generated. Some library code that is shared
|
||
with other packages also tests this symbol to see if it is being
|
||
compiled as part of the C library. We must define this before including
|
||
config.h, because it makes some definitions conditional on whether libc
|
||
itself is being compiled, or just some generator program. */
|
||
#define _LIBC 1
|
||
|
||
/* Enable declarations of GNU extensions, since we are compiling them. */
|
||
#define _GNU_SOURCE 1
|
||
/* And we also need the data for the reentrant functions. */
|
||
#define _REENTRANT 1
|
||
|
||
#include <config.h>
|
||
|
||
/* The symbols in all the user (non-_) macros are C symbols.
|
||
HAVE_GNU_LD without HAVE_ELF implies a.out. */
|
||
|
||
#if defined HAVE_ASM_WEAK_DIRECTIVE || defined HAVE_ASM_WEAKEXT_DIRECTIVE
|
||
# define HAVE_WEAK_SYMBOLS
|
||
#endif
|
||
|
||
#ifndef __SYMBOL_PREFIX
|
||
# ifdef NO_UNDERSCORES
|
||
# define __SYMBOL_PREFIX
|
||
# else
|
||
# define __SYMBOL_PREFIX "_"
|
||
# endif
|
||
#endif
|
||
|
||
#ifndef C_SYMBOL_NAME
|
||
# ifdef NO_UNDERSCORES
|
||
# define C_SYMBOL_NAME(name) name
|
||
# else
|
||
# define C_SYMBOL_NAME(name) _##name
|
||
# endif
|
||
#endif
|
||
|
||
#ifndef ASM_LINE_SEP
|
||
# define ASM_LINE_SEP ;
|
||
#endif
|
||
|
||
#ifndef C_SYMBOL_DOT_NAME
|
||
# define C_SYMBOL_DOT_NAME(name) .##name
|
||
#endif
|
||
|
||
#ifndef __ASSEMBLER__
|
||
/* GCC understands weak symbols and aliases; use its interface where
|
||
possible, instead of embedded assembly language. */
|
||
|
||
/* Define ALIASNAME as a strong alias for NAME. */
|
||
# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
|
||
# define _strong_alias(name, aliasname) \
|
||
extern __typeof (name) aliasname __attribute__ ((alias (#name)));
|
||
|
||
/* This comes between the return type and function name in
|
||
a function definition to make that definition weak. */
|
||
# define weak_function __attribute__ ((weak))
|
||
# define weak_const_function __attribute__ ((weak, __const__))
|
||
|
||
# ifdef HAVE_WEAK_SYMBOLS
|
||
|
||
/* Define ALIASNAME as a weak alias for NAME.
|
||
If weak aliases are not available, this defines a strong alias. */
|
||
# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
|
||
# define _weak_alias(name, aliasname) \
|
||
extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
|
||
|
||
/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
|
||
# define weak_extern(symbol) _weak_extern (symbol)
|
||
# ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
|
||
# define _weak_extern(symbol) asm (".weakext " __SYMBOL_PREFIX #symbol);
|
||
# else
|
||
# define _weak_extern(symbol) asm (".weak " __SYMBOL_PREFIX #symbol);
|
||
# endif
|
||
|
||
# else
|
||
|
||
# define weak_alias(name, aliasname) strong_alias(name, aliasname)
|
||
# define weak_extern(symbol) /* Nothing. */
|
||
|
||
# endif
|
||
|
||
#else /* __ASSEMBLER__ */
|
||
|
||
# ifdef HAVE_ASM_SET_DIRECTIVE
|
||
# define strong_alias(original, alias) \
|
||
ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP \
|
||
.set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
|
||
# else
|
||
# ifdef HAVE_ASM_GLOBAL_DOT_NAME
|
||
# define strong_alias(original, alias) \
|
||
ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP \
|
||
ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
|
||
# else
|
||
# define strong_alias(original, alias) \
|
||
ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
|
||
# endif
|
||
# endif
|
||
|
||
# ifdef HAVE_WEAK_SYMBOLS
|
||
# ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
|
||
# define weak_alias(original, alias) \
|
||
.weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
|
||
# define weak_extern(symbol) \
|
||
.weakext C_SYMBOL_NAME (symbol)
|
||
|
||
# else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
|
||
|
||
# ifdef HAVE_ASM_GLOBAL_DOT_NAME
|
||
# define weak_alias(original, alias) \
|
||
.weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP \
|
||
ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
|
||
# else
|
||
# define weak_alias(original, alias) \
|
||
.weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \
|
||
C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
|
||
# endif
|
||
|
||
# define weak_extern(symbol) \
|
||
.weak C_SYMBOL_NAME (symbol)
|
||
|
||
# endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
|
||
|
||
# else /* ! HAVE_WEAK_SYMBOLS */
|
||
|
||
# define weak_alias(original, alias) strong_alias(original, alias)
|
||
# define weak_extern(symbol) /* Nothing */
|
||
# endif /* ! HAVE_WEAK_SYMBOLS */
|
||
|
||
#endif /* __ASSEMBLER__ */
|
||
|
||
/* On some platforms we can make internal function calls (i.e., calls of
|
||
functions not exported) a bit faster by using a different calling
|
||
convention. */
|
||
#ifndef internal_function
|
||
# define internal_function /* empty */
|
||
#endif
|
||
|
||
/* Prepare for the case that `__builtin_expect' is not available. */
|
||
#ifndef HAVE_BUILTIN_EXPECT
|
||
# define __builtin_expect(expr, val) (expr)
|
||
#endif
|
||
|
||
/* Determine the return address. */
|
||
#define RETURN_ADDRESS(nr) \
|
||
__builtin_extract_return_addr (__builtin_return_address (nr))
|
||
|
||
/* When a reference to SYMBOL is encountered, the linker will emit a
|
||
warning message MSG. */
|
||
#ifdef HAVE_GNU_LD
|
||
# ifdef HAVE_ELF
|
||
|
||
/* We want the .gnu.warning.SYMBOL section to be unallocated. */
|
||
# ifdef HAVE_ASM_PREVIOUS_DIRECTIVE
|
||
# define __make_section_unallocated(section_string) \
|
||
asm (".section " section_string "\n\t.previous");
|
||
# elif defined HAVE_ASM_POPSECTION_DIRECTIVE
|
||
# define __make_section_unallocated(section_string) \
|
||
asm (".pushsection " section_string "\n\t.popsection");
|
||
# else
|
||
# define __make_section_unallocated(section_string)
|
||
# endif
|
||
|
||
/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
|
||
section attributes on what looks like a comment to the assembler. */
|
||
# ifdef HAVE_SECTION_QUOTES
|
||
# define link_warning(symbol, msg) \
|
||
__make_section_unallocated (".gnu.warning." #symbol) \
|
||
static const char __evoke_link_warning_##symbol[] \
|
||
__attribute__ ((unused, section (".gnu.warning." #symbol "\"\n\t#\""))) \
|
||
= msg;
|
||
# else
|
||
# define link_warning(symbol, msg) \
|
||
__make_section_unallocated (".gnu.warning." #symbol) \
|
||
static const char __evoke_link_warning_##symbol[] \
|
||
__attribute__ ((unused, section (".gnu.warning." #symbol "\n\t#"))) = msg;
|
||
# endif
|
||
# else /* Not ELF: a.out */
|
||
# ifdef HAVE_XCOFF
|
||
/* XCOFF does not support .stabs.
|
||
The native aix linker will remove the .stab and .stabstr sections
|
||
The gnu linker will have a fatal error if there is a relocation for
|
||
symbol in the .stab section. Silently disable this macro. */
|
||
# define link_warning(symbol, msg)
|
||
# else
|
||
# define link_warning(symbol, msg) \
|
||
asm (".stabs \"" msg "\",30,0,0,0\n\t" \
|
||
".stabs \"" __SYMBOL_PREFIX #symbol "\",1,0,0,0\n");
|
||
# endif /* XCOFF */
|
||
# endif
|
||
#else
|
||
/* We will never be heard; they will all die horribly. */
|
||
# define link_warning(symbol, msg)
|
||
#endif
|
||
|
||
/* A canned warning for sysdeps/stub functions. */
|
||
#define stub_warning(name) \
|
||
link_warning (name, \
|
||
"warning: " #name " is not implemented and will always fail")
|
||
|
||
/*
|
||
|
||
*/
|
||
|
||
#ifdef HAVE_GNU_LD
|
||
|
||
/* Symbol set support macros. */
|
||
|
||
# ifdef HAVE_ELF
|
||
|
||
/* Make SYMBOL, which is in the text segment, an element of SET. */
|
||
# define text_set_element(set, symbol) _elf_set_element(set, symbol)
|
||
/* Make SYMBOL, which is in the data segment, an element of SET. */
|
||
# define data_set_element(set, symbol) _elf_set_element(set, symbol)
|
||
/* Make SYMBOL, which is in the bss segment, an element of SET. */
|
||
# define bss_set_element(set, symbol) _elf_set_element(set, symbol)
|
||
|
||
/* These are all done the same way in ELF.
|
||
There is a new section created for each set. */
|
||
# ifdef SHARED
|
||
/* When building a shared library, make the set section writable,
|
||
because it will need to be relocated at run time anyway. */
|
||
# define _elf_set_element(set, symbol) \
|
||
static const void *__elf_set_##set##_element_##symbol##__ \
|
||
__attribute__ ((unused, section (#set))) = &(symbol)
|
||
# else
|
||
# define _elf_set_element(set, symbol) \
|
||
static const void *const __elf_set_##set##_element_##symbol##__ \
|
||
__attribute__ ((unused, section (#set))) = &(symbol)
|
||
# endif
|
||
|
||
/* Define SET as a symbol set. This may be required (it is in a.out) to
|
||
be able to use the set's contents. */
|
||
# define symbol_set_define(set) symbol_set_declare(set)
|
||
|
||
/* Declare SET for use in this module, if defined in another module. */
|
||
# define symbol_set_declare(set) \
|
||
extern void *const __start_##set __attribute__ ((__weak__)); \
|
||
extern void *const __stop_##set __attribute__ ((__weak__)); \
|
||
weak_extern (__start_##set) weak_extern (__stop_##set)
|
||
|
||
/* Return a pointer (void *const *) to the first element of SET. */
|
||
# define symbol_set_first_element(set) (&__start_##set)
|
||
|
||
/* Return true iff PTR (a void *const *) has been incremented
|
||
past the last element in SET. */
|
||
# define symbol_set_end_p(set, ptr) ((ptr) >= &__stop_##set)
|
||
|
||
# else /* Not ELF: a.out. */
|
||
|
||
# ifdef HAVE_XCOFF
|
||
/* XCOFF does not support .stabs.
|
||
The native aix linker will remove the .stab and .stabstr sections
|
||
The gnu linker will have a fatal error if there is a relocation for
|
||
symbol in the .stab section. Silently disable these macros. */
|
||
# define text_set_element(set, symbol)
|
||
# define data_set_element(set, symbol)
|
||
# define bss_set_element(set, symbol)
|
||
# else
|
||
# define text_set_element(set, symbol) \
|
||
asm (".stabs \"" __SYMBOL_PREFIX #set "\",23,0,0," __SYMBOL_PREFIX #symbol)
|
||
# define data_set_element(set, symbol) \
|
||
asm (".stabs \"" __SYMBOL_PREFIX #set "\",25,0,0," __SYMBOL_PREFIX #symbol)
|
||
# define bss_set_element(set, symbol) ?error Must use initialized data.
|
||
# endif /* XCOFF */
|
||
# define symbol_set_define(set) void *const (set)[1];
|
||
# define symbol_set_declare(set) extern void *const (set)[1];
|
||
|
||
# define symbol_set_first_element(set) &(set)[1]
|
||
# define symbol_set_end_p(set, ptr) (*(ptr) == 0)
|
||
|
||
# endif /* ELF. */
|
||
#else
|
||
/* We cannot do anything in generial. */
|
||
# define text_set_element(set, symbol) asm ("")
|
||
# define data_set_element(set, symbol) asm ("")
|
||
# define bss_set_element(set, symbol) asm ("")
|
||
# define symbol_set_define(set) void *const (set)[1];
|
||
# define symbol_set_declare(set) extern void *const (set)[1];
|
||
|
||
# define symbol_set_first_element(set) &(set)[1]
|
||
# define symbol_set_end_p(set, ptr) (*(ptr) == 0)
|
||
#endif /* Have GNU ld. */
|
||
|
||
#if DO_VERSIONING
|
||
# define symbol_version(real, name, version) \
|
||
_symbol_version(real, name, version)
|
||
# define default_symbol_version(real, name, version) \
|
||
_default_symbol_version(real, name, version)
|
||
# ifdef __ASSEMBLER__
|
||
# define _symbol_version(real, name, version) \
|
||
.symver real, name##@##version
|
||
# define _default_symbol_version(real, name, version) \
|
||
.symver real, name##@##@##version
|
||
# else
|
||
# define _symbol_version(real, name, version) \
|
||
__asm__ (".symver " #real "," #name "@" #version)
|
||
# define _default_symbol_version(real, name, version) \
|
||
__asm__ (".symver " #real "," #name "@@" #version)
|
||
# endif
|
||
#else
|
||
# define symbol_version(real, name, version)
|
||
# define default_symbol_version(real, name, version) \
|
||
strong_alias(real, name)
|
||
#endif
|
||
|
||
#if defined HAVE_VISIBILITY_ATTRIBUTE && defined SHARED
|
||
# define attribute_hidden __attribute__ ((visibility ("hidden")))
|
||
#else
|
||
# define attribute_hidden
|
||
#endif
|
||
|
||
/* Handling on non-exported internal names. We have to do this only
|
||
for shared code. */
|
||
#ifdef SHARED
|
||
# define INTUSE(name) name##_internal
|
||
# define INTDEF(name) strong_alias (name, name##_internal)
|
||
# define INTVARDEF(name) \
|
||
_INTVARDEF (name, name##_internal)
|
||
# if defined HAVE_VISIBILITY_ATTRIBUTE
|
||
# define _INTVARDEF(name, aliasname) \
|
||
extern __typeof (name) aliasname __attribute__ ((alias (#name), \
|
||
visibility ("hidden")));
|
||
# else
|
||
# define _INTVARDEF(name, aliasname) \
|
||
extern __typeof (name) aliasname __attribute__ ((alias (#name)));
|
||
# endif
|
||
# define INTDEF2(name, newname) strong_alias (name, newname##_internal)
|
||
# define INTVARDEF2(name, newname) _INTVARDEF (name, newname##_internal)
|
||
#else
|
||
# define INTUSE(name) name
|
||
# define INTDEF(name)
|
||
# define INTVARDEF(name)
|
||
# define INTDEF2(name, newname)
|
||
# define INTVARDEF2(name, newname)
|
||
#endif
|
||
|
||
#endif /* libc-symbols.h */
|