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7c241325d6
As a result, is not necessary to specify __attribute__ ((nocommon)) on individual definitions. GCC 10 defaults to -fno-common on all architectures except ARC, but this change is compatible with older GCC versions and ARC, too. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
154 lines
7.2 KiB
C
154 lines
7.2 KiB
C
/* Macros for managing ABI-compatibility definitions using ELF symbol versions.
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Copyright (C) 2000-2021 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, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _SHLIB_COMPAT_H
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#define _SHLIB_COMPAT_H 1
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# include <abi-versions.h>
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/* Obtain the definition of symbol_version_reference. */
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#include <libc-symver.h>
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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. */
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#define LIB_COMPAT(lib, introduced, obsoleted) \
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_LIB_COMPAT (lib, introduced, obsoleted)
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#define _LIB_COMPAT(lib, introduced, obsoleted) \
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(IS_IN (lib) \
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&& (!(ABI_##lib##_##obsoleted - 0) \
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|| ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0))))
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#ifdef SHARED
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/* Similar to LIB_COMPAT, but evaluate to 0 for static build. The
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compatibility code should be conditionalized with e.g.
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`#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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_LIB_COMPAT (lib, introduced, obsoleted)
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/* Like SHLIB_COMPAT, but it can check versions in other libraries. It is
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not always false for !IS_IN (LIB). */
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#define OTHER_SHLIB_COMPAT(lib, introduced, obsoleted) \
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_OTHER_SHLIB_COMPAT (lib, introduced, obsoleted)
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#define _OTHER_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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/* versioned_symbol (LIB, LOCAL, SYMBOL, VERSION) emits a definition
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of SYMBOL with a default (@@) VERSION appropriate for LIB. (The
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actually emitted symbol version is adjusted according to the
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baseline symbol version for LIB.) The address of the symbol is
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taken from LOCAL. Properties of LOCAL are copied to the exported
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symbol. In particular, LOCAL itself should be global. It is
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unspecified whether SYMBOL@VERSION is associated with LOCAL, or if
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an intermediate alias is created. If LOCAL and SYMBOL are
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distinct, and LOCAL is also intended for export, its version should
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be specified explicitly with versioned_symbol, too. */
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# define versioned_symbol(lib, local, symbol, version) \
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versioned_symbol_1 (lib, local, symbol, version)
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# define versioned_symbol_1(lib, local, symbol, version) \
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versioned_symbol_2 (local, symbol, VERSION_##lib##_##version)
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# define versioned_symbol_2(local, symbol, name) \
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default_symbol_version (local, symbol, name)
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/* compat_symbol is like versioned_symbol, but emits a compatibility
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version (with @ instead of @@). The same issue related to
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intermediate aliases applies, so LOCAL should not be listed in the
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Versions file, or otherwise it can be exported with an undesired
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default symbol version. */
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# define compat_symbol(lib, local, symbol, version) \
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compat_symbol_1 (lib, local, symbol, version)
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# define compat_symbol_1(lib, local, symbol, version) \
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compat_symbol_2 (local, symbol, VERSION_##lib##_##version)
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/* See <libc-symver.h>. */
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# ifdef __ASSEMBLER__
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#define compat_symbol_2(local, symbol, name) \
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_set_symbol_version (local, symbol@name)
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# else
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# define compat_symbol_2(local, symbol, name) \
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compat_symbol_3 (local, symbol, name)
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# define compat_symbol_3(local, symbol, name) \
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_set_symbol_version (local, #symbol "@" #name)
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# endif
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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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# define OTHER_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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/* Use compat_symbol_reference for a reference *or* definition of a
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specific version of a symbol. compat_symbol_reference does not
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create intermediate aliases. Definitions are primarily used to
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ensure tests reference the exact compat symbol required, or define
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an interposing symbol of the right version e.g.,
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__malloc_initialize_hook in mcheck-init.c. Use compat_symbol to
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define such a symbol within the shared libraries that are built for
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users. */
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#define compat_symbol_reference(lib, local, symbol, version) \
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compat_symbol_reference_1 (lib, local, symbol, version)
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#define compat_symbol_reference_1(lib, local, symbol, version) \
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compat_symbol_reference_2 (local, symbol, VERSION_##lib##_##version)
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#define compat_symbol_reference_2(local, symbol, name) \
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symbol_version_reference (local, symbol, name)
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/* Export the symbol only for shared-library compatibility. */
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#define libc_sunrpc_symbol(name, aliasname, version) \
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compat_symbol (libc, name, aliasname, version);
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/* The TEST_COMPAT macro acts just like the SHLIB_COMPAT macro except
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that it does not check IS_IN. It is used by tests that are testing
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functionality that is only available in specific GLIBC versions. */
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# define TEST_COMPAT(lib, introduced, obsoleted) \
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_TEST_COMPAT (lib, introduced, obsoleted)
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# define _TEST_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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#endif /* shlib-compat.h */
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