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Diffstat (limited to 'lib/libcryptsetup_symver.h')
| -rw-r--r-- | lib/libcryptsetup_symver.h | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/libcryptsetup_symver.h b/lib/libcryptsetup_symver.h new file mode 100644 index 0000000..a5aa8f9 --- /dev/null +++ b/lib/libcryptsetup_symver.h @@ -0,0 +1,103 @@ +/* + * Helpers for defining versioned symbols + * + * Copyright (C) 2021-2023 Red Hat, Inc. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef _LIBCRYPTSETUP_SYMVER_H +#define _LIBCRYPTSETUP_SYMVER_H + +/* + * Note on usage: + * + * Do not use CRYPT_SYMBOL_EXPORT_NEW and CRYPT_SYMBOL_EXPORT_OLD on public + * symbols being exported only once. Linker will handle it automatically as + * always. + * + * It's supposed to be used only with symbols that are exported in at least + * two versions simultaneously as follows: + * + * - the latest version is marked with _NEW variant and all other compatible + * symbols should be marked with _OLD variant + * + * Examples: + * + * - int crypt_func_X(unsigned *x, long y) gets introduced in CRYPTSETUP_2.4. + * + * No need to use any macro referenced here, just add proper version + * mapping in libcryptsetup.sym file. + * + * In later version CRYPTSETUP_2.5 symbol crypt_func_X has to fixed + * in incompatible way by adding new function parameter. The new version + * has to be added in mapping file libcryptsetup.sym as well. + * + * The definition of compatible function gets prefixed with following macro: + * + * CRYPT_SYMBOL_EXPORT_OLD(int, crypt_func_X, 2, 4, + * unsigned *x, long y) + * { + * function body + * } + * + * Whereas new version introduced in CRYPTSETUP_2.5 is defined as follows: + * + * CRYPT_SYMBOL_EXPORT_NEW(int, crypt_func_X, 2, 5, + * unsigned *x, long y, void *new_parameter) + * { + * function body + * } + * + * If in later version CRYPTSETUP_2.6 yet another version of crypt_func_X gets + * introduced it will be prefixed with CRYPT_SYMBOL_EXPORT_NEW(int, crypt_func_X, 2, 6...) + * macro and all previous versions CRYPTSETUP_2.4 and CRYPTSETUP_2.5 will be + * under CRYPT_SYMBOL_EXPORT_OLD(int, crypt_func_X, ...) macro + */ + +#if HAVE_ATTRIBUTE_SYMVER +# define _CRYPT_SYMVER(_local_sym, _public_sym, _ver_str, _maj, _min) \ + __attribute__((__symver__(#_public_sym _ver_str #_maj "." #_min))) +#endif + +#if !defined(_CRYPT_SYMVER) && (defined(__GNUC__) || defined(__clang__)) +# define _CRYPT_SYMVER(_local_sym, _public_sym, _ver_str, _maj, _min) \ + __asm__(".symver " #_local_sym "," #_public_sym _ver_str #_maj "." #_min); +#endif + +#define _CRYPT_FUNC(_public_sym, _prefix_str, _maj, _min, _ret, ...) \ + _ret __##_public_sym##_v##_maj##_##_min(__VA_ARGS__); \ + _CRYPT_SYMVER(__##_public_sym##_v##_maj##_##_min, _public_sym, _prefix_str "CRYPTSETUP_", _maj, _min) \ + _ret __##_public_sym##_v##_maj##_##_min(__VA_ARGS__) + +#ifdef _CRYPT_SYMVER + +# define CRYPT_SYMBOL_EXPORT_OLD(_ret, _public_sym, _maj, _min, ...) \ + _CRYPT_FUNC(_public_sym, "@", _maj, _min, _ret, __VA_ARGS__) +# define CRYPT_SYMBOL_EXPORT_NEW(_ret, _public_sym, _maj, _min, ...) \ + _CRYPT_FUNC(_public_sym, "@@", _maj, _min, _ret, __VA_ARGS__) + +#else /* no support for symbol versioning at all */ + +# define CRYPT_SYMBOL_EXPORT_OLD(_ret, _public_sym, _maj, _min, ...) \ + static inline __attribute__((unused)) \ + _ret __##_public_sym##_v##_maj##_##_min(__VA_ARGS__) + +# define CRYPT_SYMBOL_EXPORT_NEW(_ret, _public_sym, _maj, _min, ...) \ + _ret _public_sym(__VA_ARGS__) + +#endif + +#endif /* _LIBCRYPTSETUP_SYMVER_H */ |