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Diffstat (limited to 'include/libc-symbols.h')
| -rw-r--r-- | include/libc-symbols.h | 322 |
1 files changed, 322 insertions, 0 deletions
diff --git a/include/libc-symbols.h b/include/libc-symbols.h new file mode 100644 index 0000000000..07a35f1b53 --- /dev/null +++ b/include/libc-symbols.h @@ -0,0 +1,322 @@ +/* Support macros for making weak and strong aliases for symbols, + and for using symbol sets and linker warnings with GNU ld. + Copyright (C) 1995, 1996, 1997 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. 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> +/* + +*/ + +#ifndef ASSEMBLER + +/* Define the macros `_' and `N_' for conveniently marking translatable + strings in the libc source code. */ + +#define N_(msgid) msgid + +#include <libintl.h> +extern const char _libc_intl_domainname[]; + +#ifdef dgettext +/* This is defined as an optimizing macro, so use it. */ +#define _(msgid) dgettext (_libc_intl_domainname, (msgid)) +#else +/* Be sure to use only the __ name when `dgettext' is a plain function + instead of an optimizing macro. */ +#define _(msgid) __dgettext (_libc_intl_domainname, (msgid)) +#endif + +#endif + +/* + +*/ +/* 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 + + +/* Define ALIAS as a strong alias for ORIGINAL. */ +#ifdef HAVE_ASM_SET_DIRECTIVE +#define strong_alias_asm(original, alias) \ + ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias); \ + .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original) +#ifdef ASSEMBLER +#define strong_alias(original, alias) strong_alias_asm (original, alias) +#else +#define strong_alias(original, alias) \ + asm (__string_1 (ASM_GLOBAL_DIRECTIVE) " " __SYMBOL_PREFIX #alias "\n" \ + ".set " __SYMBOL_PREFIX #alias "," __SYMBOL_PREFIX #original); +#endif +#else +#define strong_alias_asm(original, alias) \ + ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias); \ + C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) +#ifdef ASSEMBLER +#define strong_alias(original, alias) strong_alias_asm (original, alias) +#else +#define strong_alias(original, alias) \ + asm (__string_1 (ASM_GLOBAL_DIRECTIVE) " " __SYMBOL_PREFIX #alias "\n" \ + __SYMBOL_PREFIX #alias " = " __SYMBOL_PREFIX #original); +#endif +#endif + +/* Helper macros used above. */ +#define __string_1(x) __string_0(x) +#define __string_0(x) #x + + +#ifdef HAVE_WEAK_SYMBOLS + +#ifdef ASSEMBLER + +#ifdef HAVE_ASM_WEAKEXT_DIRECTIVE + +/* Define ALIAS as a weak alias for ORIGINAL. + If weak aliases are not available, this defines a strong alias. */ +#define weak_alias(original, alias) \ + .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original) + +/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */ +#define weak_extern(symbol) \ + .weakext C_SYMBOL_NAME (symbol) + +#else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */ + +/* Define ALIAS as a weak alias for ORIGINAL. + If weak aliases are not available, this defines a strong alias. */ +#define weak_alias(original, alias) \ + .weak C_SYMBOL_NAME (alias); \ + C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) + + +/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */ +#define weak_extern(symbol) \ + .weak C_SYMBOL_NAME (symbol) + +#endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */ + +#else /* ! ASSEMBLER */ + +#ifdef HAVE_ASM_WEAKEXT_DIRECTIVE +#define weak_extern_asm(symbol) asm (".weakext " __SYMBOL_PREFIX #symbol); +#define weak_alias_asm(original, alias) \ + asm (".weakext " __SYMBOL_PREFIX #alias ", " __SYMBOL_PREFIX #original); +#else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */ +#define weak_extern_asm(symbol) asm (".weak " __SYMBOL_PREFIX #symbol); +#define weak_alias_asm(original, alias) \ + asm (".weak " __SYMBOL_PREFIX #alias "\n" \ + __SYMBOL_PREFIX #alias " = " __SYMBOL_PREFIX #original); +#endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */ + +#define weak_alias(o, a) weak_alias_asm (o, a) +#define weak_extern(symbol) weak_extern_asm (symbol) + +#endif /* ! ASSEMBLER */ +#else +#define weak_alias(original, alias) strong_alias(original, alias) +#define weak_extern(symbol) /* Do nothing; the ref will be strong. */ +#endif + + +#if (!defined (ASSEMBLER) && \ + (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7))) +/* GCC 2.7 and later has special syntax for weak symbols and aliases. + Using that is better when possible, because the compiler and assembler + are better clued in to what we are doing. */ +#undef strong_alias +#define strong_alias(name, aliasname) \ + extern __typeof (name) aliasname __attribute__ ((alias (#name))); + +#ifdef HAVE_WEAK_SYMBOLS +#undef weak_alias +#define weak_alias(name, aliasname) \ + extern __typeof (name) aliasname __attribute__ ((weak, 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__)) + +#endif /* HAVE_WEAK_SYMBOLS. */ +#endif /* Not ASSEMBLER, and GCC 2.7 or later. */ + + +#ifndef weak_function +/* If we do not have the __attribute__ ((weak)) syntax, there is no way we + can define functions as weak symbols. The compiler will emit a `.globl' + directive for the function symbol, and a `.weak' directive in addition + will produce an error from the assembler. */ +#define weak_function /* empty */ +#define weak_const_function /* empty */ +#endif + + +/* 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 "; .previous"); +#elif defined (HAVE_ASM_POPSECTION_DIRECTIVE) +#define __make_section_unallocated(section_string) \ + asm(".pushsection " section_string "; .popsection"); +#else +#define __make_section_unallocated(section_string) +#endif + +#define link_warning(symbol, msg) \ + __make_section_unallocated (".gnu.warning." #symbol) \ + static const char __evoke_link_warning_##symbol[] \ + __attribute__ ((section (".gnu.warning." #symbol))) = msg; +#else +#define link_warning(symbol, msg) \ + asm(".stabs \"" msg "\",30,0,0,0\n" \ + ".stabs \"" __SYMBOL_PREFIX #symbol "\",1,0,0,0\n"); +#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 PIC +/* 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. */ + +#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. +#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. */ +#endif /* Have GNU ld. */ + +#endif /* libc-symbols.h */ |