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- /* Macros for managing ABI-compatibility definitions using ELF symbol versions.
- Copyright (C) 2000-2026 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 Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 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
- Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <https://www.gnu.org/licenses/>. */
- #ifndef _SHLIB_COMPAT_H
- #define _SHLIB_COMPAT_H 1
- # include <abi-versions.h>
- /* Obtain the definition of symbol_version_reference. */
- #include <libc-symver.h>
- /* The file abi-versions.h (generated by scripts/abi-versions.awk) defines
- symbols like `ABI_libm_GLIBC_2_0' for each version set in the source
- code for each library. For a version set that is subsumed by a later
- version set, the definition gives the subsuming set, i.e. if GLIBC_2_0
- is subsumed by GLIBC_2_1, then ABI_libm_GLIBC_2_0 == ABI_libm_GLIBC_2_1.
- Each version set that is to be distinctly defined in the output has an
- unique positive integer value, increasing with newer versions. Thus,
- evaluating two ABI_* symbols reduces to integer values that differ only
- when the two version sets named are in fact two different ABIs we are
- supporting. If these do not differ, then there is no need to compile in
- extra code to support this version set where it has been superseded by a
- newer version. */
- #define LIB_COMPAT(lib, introduced, obsoleted) \
- _LIB_COMPAT (lib, introduced, obsoleted)
- #define _LIB_COMPAT(lib, introduced, obsoleted) \
- (IS_IN (lib) \
- && (!(ABI_##lib##_##obsoleted - 0) \
- || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0))))
- #ifdef SHARED
- /* Similar to LIB_COMPAT, but evaluate to 0 for static build. The
- compatibility code should be conditionalized with e.g.
- `#if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_2)' for code introduced
- in the GLIBC_2.0 version and obsoleted in the GLIBC_2.2 version. */
- # define SHLIB_COMPAT(lib, introduced, obsoleted) \
- _LIB_COMPAT (lib, introduced, obsoleted)
- /* Like SHLIB_COMPAT, but it can check versions in other libraries. It is
- not always false for !IS_IN (LIB). */
- #define OTHER_SHLIB_COMPAT(lib, introduced, obsoleted) \
- _OTHER_SHLIB_COMPAT (lib, introduced, obsoleted)
- #define _OTHER_SHLIB_COMPAT(lib, introduced, obsoleted) \
- (!(ABI_##lib##_##obsoleted - 0) \
- || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))
- /* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to
- the version set name to use for e.g. symbols first introduced into
- libm in the GLIBC_2.1 version. Definitions of symbols with explicit
- versions should look like:
- versioned_symbol (libm, new_foo, foo, GLIBC_2_1);
- This will define the symbol `foo' with the appropriate default version,
- i.e. either GLIBC_2.1 or the "earliest version" specified in
- shlib-versions if that is newer. */
- /* versioned_symbol (LIB, LOCAL, SYMBOL, VERSION) emits a definition
- of SYMBOL with a default (@@) VERSION appropriate for LIB. (The
- actually emitted symbol version is adjusted according to the
- baseline symbol version for LIB.) The address of the symbol is
- taken from LOCAL. Properties of LOCAL are copied to the exported
- symbol. In particular, LOCAL itself should be global. It is
- unspecified whether SYMBOL@VERSION is associated with LOCAL, or if
- an intermediate alias is created. If LOCAL and SYMBOL are
- distinct, and LOCAL is also intended for export, its version should
- be specified explicitly with versioned_symbol, too. */
- # define versioned_symbol(lib, local, symbol, version) \
- versioned_symbol_1 (lib, local, symbol, version)
- # define versioned_symbol_1(lib, local, symbol, version) \
- versioned_symbol_2 (local, symbol, VERSION_##lib##_##version)
- # define versioned_symbol_2(local, symbol, name) \
- default_symbol_version (local, symbol, name)
- /* compat_symbol is like versioned_symbol, but emits a compatibility
- version (with @ instead of @@). The same issue related to
- intermediate aliases applies, so LOCAL should not be listed in the
- Versions file, or otherwise it can be exported with an undesired
- default symbol version. */
- # define compat_symbol(lib, local, symbol, version) \
- compat_symbol_1 (lib, local, symbol, version)
- # define compat_symbol_1(lib, local, symbol, version) \
- compat_symbol_2 (local, symbol, VERSION_##lib##_##version)
- /* See <libc-symver.h>. */
- # ifdef __ASSEMBLER__
- #define compat_symbol_2(local, symbol, name) \
- _set_symbol_version (local, symbol@name)
- # else
- # define compat_symbol_2(local, symbol, name) \
- compat_symbol_3 (local, symbol, name)
- # define compat_symbol_3(local, symbol, name) \
- _set_symbol_version (local, #symbol "@" #name)
- # endif
- #else
- /* Not compiling ELF shared libraries at all, so never any old versions. */
- # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
- # define OTHER_SHLIB_COMPAT(lib, introduced, obsoleted) 0
- /* No versions to worry about, just make this the global definition. */
- # define versioned_symbol(lib, local, symbol, version) \
- weak_alias (local, symbol)
- /* This should not appear outside `#if SHLIB_COMPAT (...)'. */
- # define compat_symbol(lib, local, symbol, version) ...
- #endif
- /* Use compat_symbol_reference for a reference *or* definition of a
- specific version of a symbol. compat_symbol_reference does not
- create intermediate aliases. Definitions are primarily used to
- ensure tests reference the exact compat symbol required, or define
- an interposing symbol of the right version e.g.,
- __malloc_initialize_hook in mcheck-init.c. Use compat_symbol to
- define such a symbol within the shared libraries that are built for
- users. */
- #define compat_symbol_reference(lib, local, symbol, version) \
- compat_symbol_reference_1 (lib, local, symbol, version)
- #define compat_symbol_reference_1(lib, local, symbol, version) \
- compat_symbol_reference_2 (local, symbol, VERSION_##lib##_##version)
- #define compat_symbol_reference_2(local, symbol, name) \
- symbol_version_reference (local, symbol, name)
- /* Export the symbol only for shared-library compatibility. */
- #define libc_sunrpc_symbol(name, aliasname, version) \
- compat_symbol (libc, name, aliasname, version);
- /* The TEST_COMPAT macro acts just like the SHLIB_COMPAT macro except
- that it does not check IS_IN. It is used by tests that are testing
- functionality that is only available in specific GLIBC versions. */
- # define TEST_COMPAT(lib, introduced, obsoleted) \
- _TEST_COMPAT (lib, introduced, obsoleted)
- # define _TEST_COMPAT(lib, introduced, obsoleted) \
- (!(ABI_##lib##_##obsoleted - 0) \
- || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))
- #endif /* shlib-compat.h */
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