| /* 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 */ |