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46c1c765d1
This reverts commit 20b39d5946 for static
library. This avoids the need to rebuild the world for the case where
libstdc++ (and potentially other libraries) are linked to a old glibc.
To avoid requering to provide xstat symbols for newer ABIs (such as
riscv32) a new LIB_COMPAT macro is added. It is similar to SHLIB_COMPAT
but also works for static case (thus evaluating similar to SHLIB_COMPAT
for both shared and static case).
Checked with a check-abi on all affected ABIs. I also check if the
static library does contains the xstat symbols.
150 lines
6.6 KiB
C
150 lines
6.6 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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/* 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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/* 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 (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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# define compat_symbol(lib, local, symbol, version) \
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compat_symbol_reference (lib, local, symbol, version)
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/* This is similar to compat_symbol, but allows versioning the same symbol
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to multiple version without having multiple symbol definitions. For
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instance:
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#if (SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_2))
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compat_symbol_unique (libc, old_foo, GLIBC_2_1_2)
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#endif
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#if (SHLIB_COMPAT (libpthread, GLIBC_2_2_6, GLIBC_2_3))
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compat_symbol_unique (libc, old_foo, GLIBC_2_2_6)
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#endif
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Internally it creates a unique strong alias to the input symbol and
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creates one compat_symbol on the alias. Using the above example,
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it is similar to:
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#if (SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_2))
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strong_alias (old_foo, old_foo__COUNTER__)
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compat_symbol (libc, old_foo__COUNTER__, foo, GLIBC_2_2)
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#endif.
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With __COUNTER__ being a monotonic number generated by the compiler. */
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# define __compat_symbol_unique_concat(x, y) x ## y
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# define _compat_symbol_unique_concat(x, y) \
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__compat_symbol_unique_concat (x, y)
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# define _compat_symbol_unique_alias(name) \
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_compat_symbol_unique_concat (name, __COUNTER__)
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# define _compat_symbol_unique(lib, orig_name, name, version) \
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strong_alias (orig_name, name) \
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compat_symbol (lib, name, orig_name, version)
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# define compat_symbol_unique(lib, name, version) \
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_compat_symbol_unique (lib, name, _compat_symbol_unique_alias (name), \
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version)
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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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# define compat_symbol_unique(lib, name, 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. Definitions are primarily used to
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ensure tests reference the exact compat symbol required, or define an
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interposing symbol of the right version e.g. __malloc_initialize_hook
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in mcheck-init.c. Use compat_symbol to define such a symbol within
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the shared libraries that are built for 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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