1 /* Macros for managing ABI-compatibility definitions using ELF symbol versions. 2 Copyright (C) 2000, 2002 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 Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the 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 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, write to the Free 17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 18 02111-1307 USA. */ 19 20 #ifndef _SHLIB_COMPAT_H 21 #define _SHLIB_COMPAT_H 1 22 23 #if defined HAVE_ELF && defined DO_VERSIONING 24 /* Since there is just one set of .d files generated, we need to 25 include this unconditionally to have the dependency noticed properly. */ 26 #include <abi-versions.h> /* header generated by abi-versions.awk */ 27 #endif 28 29 #if defined HAVE_ELF && defined SHARED && defined DO_VERSIONING 30 31 /* The file abi-versions.h (generated by scripts/abi-versions.awk) defines 32 symbols like `ABI_libm_GLIBC_2_0' for each version set in the source 33 code for each library. For a version set that is subsumed by a later 34 version set, the definition gives the subsuming set, i.e. if GLIBC_2_0 35 is subsumed by GLIBC_2_1, then ABI_libm_GLIBC_2_0 == ABI_libm_GLIBC_2_1. 36 Each version set that is to be distinctly defined in the output has an 37 unique positive integer value, increasing with newer versions. Thus, 38 evaluating two ABI_* symbols reduces to integer values that differ only 39 when the two version sets named are in fact two different ABIs we are 40 supporting. If these do not differ, then there is no need to compile in 41 extra code to support this version set where it has been superseded by a 42 newer version. The compatibility code should be conditionalized with 43 e.g. `#if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_2)' for code introduced 44 in the GLIBC_2.0 version and obsoleted in the GLIBC_2.2 version. */ 45 46 # define SHLIB_COMPAT(lib, introduced, obsoleted) \ 47 ((IS_IN_##lib - 0) \ 48 && (!(ABI_##lib##_##obsoleted - 0) \ 49 || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))) 50 51 # ifndef NOT_IN_libc 52 # define IS_IN_libc 1 53 # endif 54 55 /* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to 56 the version set name to use for e.g. symbols first introduced into 57 libm in the GLIBC_2.1 version. Definitions of symbols with explicit 58 versions should look like: 59 versioned_symbol (libm, new_foo, foo, GLIBC_2_1); 60 This will define the symbol `foo' with the appropriate default version, 61 i.e. either GLIBC_2.1 or the "earliest version" specified in 62 shlib-versions if that is newer. */ 63 64 # define versioned_symbol(lib, local, symbol, version) \ 65 versioned_symbol_1 (local, symbol, VERSION_##lib##_##version) 66 # define versioned_symbol_1(local, symbol, name) \ 67 default_symbol_version (local, symbol, name) 68 69 # define compat_symbol(lib, local, symbol, version) \ 70 compat_symbol_1 (local, symbol, VERSION_##lib##_##version) 71 # define compat_symbol_1(local, symbol, name) \ 72 symbol_version (local, symbol, name) 73 74 #else 75 76 /* Not compiling ELF shared libraries at all, so never any old versions. */ 77 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0 78 79 /* No versions to worry about, just make this the global definition. */ 80 # define versioned_symbol(lib, local, symbol, version) \ 81 weak_alias (local, symbol) 82 83 /* This should not appear outside `#if SHLIB_COMPAT (...)'. */ 84 # define compat_symbol(lib, local, symbol, version) ... 85 86 #endif 87 88 89 #endif /* shlib-compat.h */ 90