diff options
Diffstat (limited to 'include/shlib-compat.h')
| -rw-r--r-- | include/shlib-compat.h | 82 |
1 files changed, 39 insertions, 43 deletions
diff --git a/include/shlib-compat.h b/include/shlib-compat.h index b874e2588f..537851d753 100644 --- a/include/shlib-compat.h +++ b/include/shlib-compat.h @@ -62,6 +62,20 @@ 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. + + If LOCAL is a data symbol and does not have a non-zero initializer, + it should be defined with __attribute__ ((nocommon)) for + compatibility with GCC versions that default to -fcommon. */ # define versioned_symbol(lib, local, symbol, version) \ versioned_symbol_1 (lib, local, symbol, version) # define versioned_symbol_1(lib, local, symbol, version) \ @@ -69,44 +83,25 @@ # 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_reference (lib, local, symbol, version) - -/* This is similar to compat_symbol, but allows versioning the same symbol - to multiple version without having multiple symbol definitions. For - instance: - - #if (SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_2)) - compat_symbol_unique (libc, old_foo, GLIBC_2_1_2) - #endif - - #if (SHLIB_COMPAT (libpthread, GLIBC_2_2_6, GLIBC_2_3)) - compat_symbol_unique (libc, old_foo, GLIBC_2_2_6) - #endif - - Internally it creates a unique strong alias to the input symbol and - creates one compat_symbol on the alias. Using the above example, - it is similar to: - - #if (SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_2)) - strong_alias (old_foo, old_foo__COUNTER__) - compat_symbol (libc, old_foo__COUNTER__, foo, GLIBC_2_2) - #endif. - - With __COUNTER__ being a monotonic number generated by the compiler. */ - -# define __compat_symbol_unique_concat(x, y) x ## y -# define _compat_symbol_unique_concat(x, y) \ - __compat_symbol_unique_concat (x, y) -# define _compat_symbol_unique_alias(name) \ - _compat_symbol_unique_concat (name, __COUNTER__) -# define _compat_symbol_unique(lib, orig_name, name, version) \ - strong_alias (orig_name, name) \ - compat_symbol (lib, name, orig_name, version) -# define compat_symbol_unique(lib, name, version) \ - _compat_symbol_unique (lib, name, _compat_symbol_unique_alias (name), \ - 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. */ @@ -118,16 +113,17 @@ /* This should not appear outside `#if SHLIB_COMPAT (...)'. */ # define compat_symbol(lib, local, symbol, version) ... -# define compat_symbol_unique(lib, name, version) ... #endif /* Use compat_symbol_reference for a reference *or* definition of a - specific version of a symbol. 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. */ + 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) \ |