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361742ed | 1 | /* Macros for managing ABI-compatibility definitions using ELF symbol versions. |
2b778ceb | 2 | Copyright (C) 2000-2021 Free Software Foundation, Inc. |
361742ed RM |
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 | |
41bdb6e2 AJ |
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. | |
361742ed RM |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
361742ed | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
361742ed RM |
18 | |
19 | #ifndef _SHLIB_COMPAT_H | |
20 | #define _SHLIB_COMPAT_H 1 | |
21 | ||
3f2e46a4 | 22 | # include <abi-versions.h> |
361742ed | 23 | |
3a24ddea FW |
24 | /* Obtain the definition of symbol_version_reference. */ |
25 | #include <libc-symver.h> | |
26 | ||
361742ed | 27 | /* The file abi-versions.h (generated by scripts/abi-versions.awk) defines |
cb832354 RM |
28 | symbols like `ABI_libm_GLIBC_2_0' for each version set in the source |
29 | code for each library. For a version set that is subsumed by a later | |
30 | version set, the definition gives the subsuming set, i.e. if GLIBC_2_0 | |
31 | is subsumed by GLIBC_2_1, then ABI_libm_GLIBC_2_0 == ABI_libm_GLIBC_2_1. | |
32 | Each version set that is to be distinctly defined in the output has an | |
33 | unique positive integer value, increasing with newer versions. Thus, | |
34 | evaluating two ABI_* symbols reduces to integer values that differ only | |
35 | when the two version sets named are in fact two different ABIs we are | |
36 | supporting. If these do not differ, then there is no need to compile in | |
37 | extra code to support this version set where it has been superseded by a | |
46c1c765 AZ |
38 | newer version. */ |
39 | #define LIB_COMPAT(lib, introduced, obsoleted) \ | |
40 | _LIB_COMPAT (lib, introduced, obsoleted) | |
41 | #define _LIB_COMPAT(lib, introduced, obsoleted) \ | |
286663c3 | 42 | (IS_IN (lib) \ |
ce460d04 RM |
43 | && (!(ABI_##lib##_##obsoleted - 0) \ |
44 | || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))) | |
45 | ||
46c1c765 AZ |
46 | #ifdef SHARED |
47 | ||
48 | /* Similar to LIB_COMPAT, but evaluate to 0 for static build. The | |
49 | compatibility code should be conditionalized with e.g. | |
50 | `#if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_2)' for code introduced | |
51 | in the GLIBC_2.0 version and obsoleted in the GLIBC_2.2 version. */ | |
52 | ||
53 | # define SHLIB_COMPAT(lib, introduced, obsoleted) \ | |
54 | _LIB_COMPAT (lib, introduced, obsoleted) | |
55 | ||
361742ed RM |
56 | /* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to |
57 | the version set name to use for e.g. symbols first introduced into | |
58 | libm in the GLIBC_2.1 version. Definitions of symbols with explicit | |
59 | versions should look like: | |
350635a5 | 60 | versioned_symbol (libm, new_foo, foo, GLIBC_2_1); |
361742ed RM |
61 | This will define the symbol `foo' with the appropriate default version, |
62 | i.e. either GLIBC_2.1 or the "earliest version" specified in | |
63 | shlib-versions if that is newer. */ | |
64 | ||
0923f74a FW |
65 | /* versioned_symbol (LIB, LOCAL, SYMBOL, VERSION) emits a definition |
66 | of SYMBOL with a default (@@) VERSION appropriate for LIB. (The | |
67 | actually emitted symbol version is adjusted according to the | |
68 | baseline symbol version for LIB.) The address of the symbol is | |
69 | taken from LOCAL. Properties of LOCAL are copied to the exported | |
70 | symbol. In particular, LOCAL itself should be global. It is | |
71 | unspecified whether SYMBOL@VERSION is associated with LOCAL, or if | |
72 | an intermediate alias is created. If LOCAL and SYMBOL are | |
73 | distinct, and LOCAL is also intended for export, its version should | |
74 | be specified explicitly with versioned_symbol, too. | |
75 | ||
76 | If LOCAL is a data symbol and does not have a non-zero initializer, | |
77 | it should be defined with __attribute__ ((nocommon)) for | |
78 | compatibility with GCC versions that default to -fcommon. */ | |
cb162e13 | 79 | # define versioned_symbol(lib, local, symbol, version) \ |
11bf311e UD |
80 | versioned_symbol_1 (lib, local, symbol, version) |
81 | # define versioned_symbol_1(lib, local, symbol, version) \ | |
82 | versioned_symbol_2 (local, symbol, VERSION_##lib##_##version) | |
83 | # define versioned_symbol_2(local, symbol, name) \ | |
cb162e13 | 84 | default_symbol_version (local, symbol, name) |
361742ed | 85 | |
0923f74a FW |
86 | /* compat_symbol is like versioned_symbol, but emits a compatibility |
87 | version (with @ instead of @@). The same issue related to | |
88 | intermediate aliases applies, so LOCAL should not be listed in the | |
89 | Versions file, or otherwise it can be exported with an undesired | |
90 | default symbol version. */ | |
2ae13e20 | 91 | # define compat_symbol(lib, local, symbol, version) \ |
0923f74a FW |
92 | compat_symbol_1 (lib, local, symbol, version) |
93 | # define compat_symbol_1(lib, local, symbol, version) \ | |
94 | compat_symbol_2 (local, symbol, VERSION_##lib##_##version) | |
95 | /* See <libc-symver.h>. */ | |
96 | # ifdef __ASSEMBLER__ | |
97 | #define compat_symbol_2(local, symbol, name) \ | |
98 | _set_symbol_version (local, symbol@name) | |
99 | # else | |
100 | # define compat_symbol_2(local, symbol, name) \ | |
101 | compat_symbol_3 (local, symbol, name) | |
102 | # define compat_symbol_3(local, symbol, name) \ | |
103 | _set_symbol_version (local, #symbol "@" #name) | |
104 | # endif | |
361742ed RM |
105 | #else |
106 | ||
107 | /* Not compiling ELF shared libraries at all, so never any old versions. */ | |
cb832354 | 108 | # define SHLIB_COMPAT(lib, introduced, obsoleted) 0 |
361742ed RM |
109 | |
110 | /* No versions to worry about, just make this the global definition. */ | |
cb162e13 | 111 | # define versioned_symbol(lib, local, symbol, version) \ |
361742ed RM |
112 | weak_alias (local, symbol) |
113 | ||
2ae13e20 RM |
114 | /* This should not appear outside `#if SHLIB_COMPAT (...)'. */ |
115 | # define compat_symbol(lib, local, symbol, version) ... | |
116 | ||
361742ed RM |
117 | #endif |
118 | ||
3480ddc4 | 119 | /* Use compat_symbol_reference for a reference *or* definition of a |
0923f74a FW |
120 | specific version of a symbol. compat_symbol_reference does not |
121 | create intermediate aliases. Definitions are primarily used to | |
122 | ensure tests reference the exact compat symbol required, or define | |
123 | an interposing symbol of the right version e.g., | |
124 | __malloc_initialize_hook in mcheck-init.c. Use compat_symbol to | |
125 | define such a symbol within the shared libraries that are built for | |
126 | users. */ | |
968dc26d FW |
127 | #define compat_symbol_reference(lib, local, symbol, version) \ |
128 | compat_symbol_reference_1 (lib, local, symbol, version) | |
129 | #define compat_symbol_reference_1(lib, local, symbol, version) \ | |
130 | compat_symbol_reference_2 (local, symbol, VERSION_##lib##_##version) | |
131 | #define compat_symbol_reference_2(local, symbol, name) \ | |
132 | symbol_version_reference (local, symbol, name) | |
361742ed | 133 | |
07c58f8f | 134 | /* Export the symbol only for shared-library compatibility. */ |
5500cdba | 135 | #define libc_sunrpc_symbol(name, aliasname, version) \ |
07c58f8f | 136 | compat_symbol (libc, name, aliasname, version); |
07c58f8f | 137 | |
05b38d64 SE |
138 | /* The TEST_COMPAT macro acts just like the SHLIB_COMPAT macro except |
139 | that it does not check IS_IN. It is used by tests that are testing | |
140 | functionality that is only available in specific GLIBC versions. */ | |
141 | ||
142 | # define TEST_COMPAT(lib, introduced, obsoleted) \ | |
143 | _TEST_COMPAT (lib, introduced, obsoleted) | |
144 | # define _TEST_COMPAT(lib, introduced, obsoleted) \ | |
145 | (!(ABI_##lib##_##obsoleted - 0) \ | |
146 | || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0))) | |
147 | ||
361742ed | 148 | #endif /* shlib-compat.h */ |