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0487ebed22
This patch adds the missing __libpthread_version_placeholder for GLIBC_2.2.6 version from the nanosleep implementation move from libpthread to libc (79a547b162). It also fixes the wrong compat symbol definitions added by changing back the version used on vfork check and remove the __libpthread_version_placeholder added on some ABI (4f4bb489e0). The __libpthread_version_placeholder is also refactored to make it simpler to add new compat_symbols by adding a new macro compat_symbol_unique which uses the compiler extension __COUNTER__ to generate unique strong alias to be used with compat_symbol. Checked with a updated-abi on the all affected abis of the nanosleep move. Change-Id: I347a4dbdc931bb42b359456932dd1e17aa4d4078
151 lines
6.6 KiB
C
151 lines
6.6 KiB
C
/* Macros for managing ABI-compatibility definitions using ELF symbol versions.
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Copyright (C) 2000-2019 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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#ifdef SHARED
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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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_SHLIB_COMPAT (lib, introduced, obsoleted)
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# define _SHLIB_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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/* 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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# ifdef LINK_OBSOLETE_RPC
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/* Export the symbol for both static and dynamic linking. */
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# define libc_sunrpc_symbol(name, aliasname, version) \
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strong_alias (name, aliasname)
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# else
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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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# endif
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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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