1  /* Symbol version management.
       2     Copyright (C) 1995-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  /* This file is included from <libc-symbols.h> for !_ISOMAC, and
      20     unconditionally from <shlib-compat.h>.  */
      21  
      22  #ifndef _LIBC_SYMVER_H
      23  #define _LIBC_SYMVER_H 1
      24  
      25  #include <config.h>
      26  
      27  /* Use symbol_version_reference to specify the version a symbol
      28     reference should link to.  Use symbol_version or
      29     default_symbol_version for the definition of a versioned symbol.
      30     The difference is that the latter is a no-op in non-shared
      31     builds.
      32  
      33     _set_symbol_version is similar to symbol_version_reference, except
      34     that this macro expects the name and symbol version as a single
      35     string or token sequence, with an @ or @@ separator.  (A string is
      36     used in C mode and a token sequence in assembler mode.)
      37     _set_symbol_version only be used for definitions because it may
      38     introduce an alias symbol that would not be globally unique for
      39     mere references.  The _set_symbol_version macro is used to define
      40     default_symbol_version and compat_symbol.  */
      41  
      42  #ifdef __ASSEMBLER__
      43  # define symbol_version_reference(real, name, version) \
      44       .symver real, name##@##version
      45  #else
      46  # define symbol_version_reference(real, name, version) \
      47    __asm__ (".symver " #real "," #name "@" #version)
      48  #endif  /* !__ASSEMBLER__ */
      49  
      50  #if SYMVER_NEEDS_ALIAS
      51  /* If the assembler cannot support multiple versions for the same
      52     symbol, introduce __SInnn_ aliases to which the symbol version is
      53     attached.  */
      54  # define __symbol_version_unique_concat(x, y) __SI ## x ## _ ## y
      55  # define _symbol_version_unique_concat(x, y) \
      56    __symbol_version_unique_concat (x, y)
      57  # define _symbol_version_unique_alias(name) \
      58    _symbol_version_unique_concat (name, __COUNTER__)
      59  # ifdef __ASSEMBLER__
      60  #  define _set_symbol_version_2(real, alias, name_version) \
      61    .globl alias ASM_LINE_SEP                                \
      62    .equiv alias, real ASM_LINE_SEP                          \
      63    .symver alias, name_version
      64  # else
      65  #  define _set_symbol_version_2(real, alias, name_version) \
      66    __asm__ (".globl " #alias "\n\t"                         \
      67             ".equiv " #alias ", " #real "\n\t"              \
      68             ".symver " #alias "," name_version)
      69  # endif
      70  # define _set_symbol_version_1(real, alias, name_version) \
      71    _set_symbol_version_2 (real, alias, name_version)
      72  /* REAL must be globally unique, so that the counter also produces
      73     globally unique symbols.  */
      74  # define _set_symbol_version(real, name_version)                   \
      75    _set_symbol_version_1 (real, _symbol_version_unique_alias (real), \
      76                                 name_version)
      77  # else  /* !SYMVER_NEEDS_ALIAS */
      78  # ifdef __ASSEMBLER__
      79  #  define _set_symbol_version(real, name_version) \
      80    .symver real, name_version
      81  # else
      82  #  define _set_symbol_version(real, name_version) \
      83    __asm__ (".symver " #real "," name_version)
      84  # endif
      85  #endif  /* !SYMVER_NEEDS_ALIAS */
      86  
      87  
      88  #endif /* _LIBC_SYMVER_H */