1 files changed, 182 insertions, 0 deletions
diff --git a/libc-symbols.h b/libc-symbols.h
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+/* Support macros for making weak and strong aliases for symbols,
+   and for using symbol sets and linker warnings with GNU ld.
+Copyright (C) 1995 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., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#ifndef _LIBC_SYMBOLS_H
+#define _LIBC_SYMBOLS_H
+
+/* 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_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.
+   This implies HAVE_WEAK_SYMBOLS; set by --with-gnu-ld.
+   * HAVE_ELF if using ELF, which supports weak symbols.
+   This implies HAVE_WEAK_SYMBOLS; set by --with-elf.
+
+   * HAVE_WEAK_SYMBOLS if weak symbols are available in the assembler and
+   linker being used.  Set by --with-weak-symbols.
+
+   */
+#include <config.h>
+
+/* 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.  */
+#define _LIBC
+
+/* The symbols in all the user (non-_) macros are C symbols.  Predefined
+   should be HAVE_WEAK_SYMBOLS and/or HAVE_ELF and/or HAVE_GNU_LD.
+   HAVE_WEAK_SYMBOLS is implied by the other two.  HAVE_GNU_LD without
+   HAVE_ELF implies a.out.  */
+
+#ifndef HAVE_WEAK_SYMBOLS
+#if defined (HAVE_ELF) || defined (HAVE_GNU_LD)
+#define HAVE_WEAK_SYMBOLS
+#endif
+#endif
+
+#ifndef __SYMBOL_PREFIX
+#ifdef HAVE_ELF
+#define NO_UNDERSCORES
+#else
+#include <sysdep.h>		/* Should define NO_UNDERSCORES.  */
+#endif
+#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.  */
+#define strong_alias_asm(original, 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 (".set " __SYMBOL_PREFIX #alias "," __SYMBOL_PREFIX #original);
+#endif
+
+/* Define ALIAS as a weak alias for ORIGINAL.
+   If weak aliases are not available, this defines a strong alias.  */
+#ifdef HAVE_WEAK_SYMBOLS
+#ifdef ASSEMBLER
+#define weak_alias(original, alias)	\
+  .weak C_SYMBOL_NAME (alias);	\
+  C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
+#else
+#define weak_alias(original, alias) \
+  asm (".weak " __SYMBOL_PREFIX #alias "\n" \
+       __SYMBOL_PREFIX #alias " = " __SYMBOL_PREFIX #original);
+#endif
+#else
+#define	weak_alias(original, alias) strong_alias(original, alias)
+#endif
+
+
+
+/* When the file using this macro is linked in, the linker
+   will emit a warning message MSG.  */
+#ifdef HAVE_GNU_LD
+#ifdef HAVE_ELF
+#define link_warning(msg)			\
+  static const char __evoke_link_warning__[]	\
+    __attribute__ ((section (".gnu.warning"))) = msg;
+#else
+#define link_warning(msg)		\
+  asm(".stabs \"" msg "\",30,0,0,0\n"	\
+      ".stabs \"__evoke_link_warning__\",1,0,0,0\n"\
+      ".stabs \"__evoke_link_warning__\",2,0,0,0\n");
+#endif
+#else
+/* We will never be heard; they will all die horribly.  */
+#define link_warning(msg)
+#endif
+
+/* A canned warning for sysdeps/stub functions.  */
+#define	stub_warning(name) \
+  link_warning ("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.  */
+#define _elf_set_element(set, symbol) \
+  static const void *const __elf_set_##set##_element_##symbol##__ \
+    __attribute__ ((section (#set))) = &(symbol)
+
+/* 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, *const __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 */