include/shlib-compat.h

   1 /* Macros for managing ABI-compatibility definitions using ELF symbol versions.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #ifndef _SHLIB_COMPAT_H
  21 #define _SHLIB_COMPAT_H 1
  22
  23 #if defined HAVE_ELF && defined PIC && defined DO_VERSIONING
  24
  25 # include <abi-versions.h>      /* header generated by abi-versions.awk */
  26
  27 /* The file abi-versions.h (generated by scripts/abi-versions.awk) defines
  28    symbols like `ABI_libm_GLIBC_2_0' to either 1 or 0 indicating whether or
  29    not we want to build binary compatibility for e.g. the GLIBC_2.0 version
  30    set into the libm shared object.  If this evaluates to zero, then there
  31    is no need to compile in extra code to support this version set where it
  32    has been superseded by a newer version.  The compatibility code should
  33    be conditionalized with `#if SHLIB_COMPAT (libm, GLIBC_2_0)'.  */
  34
  35 # define SHLIB_COMPAT(lib, version)     ABI_##lib##_##version
  36
  37 /* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to
  38    the version set name to use for e.g. symbols first introduced into
  39    libm in the GLIBC_2.1 version.  Definitions of symbols with explicit
  40    versions should look like:
  41         versioned_symbol (libm, new_foo, foo, GLIBC_2_1);
  42    This will define the symbol `foo' with the appropriate default version,
  43    i.e. either GLIBC_2.1 or the "earliest version" specified in
  44    shlib-versions if that is newer.  */
  45
  46 # define versioned_symbol(lib, local, symbol, version) \
  47   versioned_symbol2 (local, symbol, VERSION_##lib##_##version)
  48 # define versioned_symbol2(local, symbol, name) \
  49   default_symbol_version (local, symbol, name)
  50
  51 #else
  52
  53 /* Not compiling ELF shared libraries at all, so never any old versions.  */
  54 # define SHLIB_COMPAT(lib, version)     0
  55
  56 /* No versions to worry about, just make this the global definition.  */
  57 # define versioned_symbol(lib, local, symbol, version) \
  58   weak_alias (local, symbol)
  59
  60 #endif
  61
  62
  63 #endif  /* shlib-compat.h */