85 lines
3.8 KiB
C
85 lines
3.8 KiB
C
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/* Macros for managing ABI-compatibility definitions using ELF symbol versions.
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Copyright (C) 2000 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#ifndef _SHLIB_COMPAT_H
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#define _SHLIB_COMPAT_H 1
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#if defined HAVE_ELF && defined DO_VERSIONING
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/* Since there is just one set of .d files generated, we need to
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include this unconditionally to have the dependency noticed properly. */
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#include <abi-versions.h> /* header generated by abi-versions.awk */
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#endif
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#if defined HAVE_ELF && defined SHARED && defined DO_VERSIONING
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/* The file abi-versions.h (generated by scripts/abi-versions.awk) defines
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symbols like `ABI_libm_GLIBC_2_0' for each version set in the source
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code for each library. For a version set that is subsumed by a later
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version set, the definition gives the subsuming set, i.e. if GLIBC_2_0
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is subsumed by GLIBC_2_1, then ABI_libm_GLIBC_2_0 == ABI_libm_GLIBC_2_1.
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Each version set that is to be distinctly defined in the output has an
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unique positive integer value, increasing with newer versions. Thus,
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evaluating two ABI_* symbols reduces to integer values that differ only
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when the two version sets named are in fact two different ABIs we are
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supporting. If these do not differ, then there is no need to compile in
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extra code to support this version set where it has been superseded by a
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newer version. The compatibility code should be conditionalized with
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e.g. `#if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_2)' for code introduced
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in the GLIBC_2.0 version and obsoleted in the GLIBC_2.2 version. */
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# define SHLIB_COMPAT(lib, introduced, obsoleted) \
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(!(ABI_##lib##_##obsoleted - 0) \
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|| ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))
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/* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to
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the version set name to use for e.g. symbols first introduced into
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libm in the GLIBC_2.1 version. Definitions of symbols with explicit
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versions should look like:
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versioned_symbol (libm, new_foo, foo, GLIBC_2_1);
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This will define the symbol `foo' with the appropriate default version,
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i.e. either GLIBC_2.1 or the "earliest version" specified in
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shlib-versions if that is newer. */
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# define versioned_symbol(lib, local, symbol, version) \
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versioned_symbol_1 (local, symbol, VERSION_##lib##_##version)
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# define versioned_symbol_1(local, symbol, name) \
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default_symbol_version (local, symbol, name)
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# define compat_symbol(lib, local, symbol, version) \
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compat_symbol_1 (local, symbol, VERSION_##lib##_##version)
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# define compat_symbol_1(local, symbol, name) \
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symbol_version (local, symbol, name)
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#else
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/* Not compiling ELF shared libraries at all, so never any old versions. */
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# define SHLIB_COMPAT(lib, introduced, obsoleted) 0
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/* No versions to worry about, just make this the global definition. */
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# define versioned_symbol(lib, local, symbol, version) \
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weak_alias (local, symbol)
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/* This should not appear outside `#if SHLIB_COMPAT (...)'. */
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# define compat_symbol(lib, local, symbol, version) ...
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#endif
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#endif /* shlib-compat.h */
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