1 | /* Macros for managing ABI-compatibility definitions using ELF symbol versions. |
2 | Copyright (C) 2000-2017 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 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #ifndef _SHLIB_COMPAT_H |
20 | #define _SHLIB_COMPAT_H 1 |
21 | |
22 | # include <abi-versions.h> |
23 | |
24 | #ifdef SHARED |
25 | |
26 | /* The file abi-versions.h (generated by scripts/abi-versions.awk) defines |
27 | symbols like `ABI_libm_GLIBC_2_0' for each version set in the source |
28 | code for each library. For a version set that is subsumed by a later |
29 | version set, the definition gives the subsuming set, i.e. if GLIBC_2_0 |
30 | is subsumed by GLIBC_2_1, then ABI_libm_GLIBC_2_0 == ABI_libm_GLIBC_2_1. |
31 | Each version set that is to be distinctly defined in the output has an |
32 | unique positive integer value, increasing with newer versions. Thus, |
33 | evaluating two ABI_* symbols reduces to integer values that differ only |
34 | when the two version sets named are in fact two different ABIs we are |
35 | supporting. If these do not differ, then there is no need to compile in |
36 | extra code to support this version set where it has been superseded by a |
37 | newer version. The compatibility code should be conditionalized with |
38 | e.g. `#if SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_2)' for code introduced |
39 | in the GLIBC_2.0 version and obsoleted in the GLIBC_2.2 version. */ |
40 | |
41 | # define SHLIB_COMPAT(lib, introduced, obsoleted) \ |
42 | _SHLIB_COMPAT (lib, introduced, obsoleted) |
43 | # define _SHLIB_COMPAT(lib, introduced, obsoleted) \ |
44 | (IS_IN (lib) \ |
45 | && (!(ABI_##lib##_##obsoleted - 0) \ |
46 | || ((ABI_##lib##_##introduced - 0) < (ABI_##lib##_##obsoleted - 0)))) |
47 | |
48 | /* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to |
49 | the version set name to use for e.g. symbols first introduced into |
50 | libm in the GLIBC_2.1 version. Definitions of symbols with explicit |
51 | versions should look like: |
52 | versioned_symbol (libm, new_foo, foo, GLIBC_2_1); |
53 | This will define the symbol `foo' with the appropriate default version, |
54 | i.e. either GLIBC_2.1 or the "earliest version" specified in |
55 | shlib-versions if that is newer. */ |
56 | |
57 | # define versioned_symbol(lib, local, symbol, version) \ |
58 | versioned_symbol_1 (lib, local, symbol, version) |
59 | # define versioned_symbol_1(lib, local, symbol, version) \ |
60 | versioned_symbol_2 (local, symbol, VERSION_##lib##_##version) |
61 | # define versioned_symbol_2(local, symbol, name) \ |
62 | default_symbol_version (local, symbol, name) |
63 | |
64 | # define compat_symbol(lib, local, symbol, version) \ |
65 | compat_symbol_reference (lib, local, symbol, version) |
66 | |
67 | #else |
68 | |
69 | /* Not compiling ELF shared libraries at all, so never any old versions. */ |
70 | # define SHLIB_COMPAT(lib, introduced, obsoleted) 0 |
71 | |
72 | /* No versions to worry about, just make this the global definition. */ |
73 | # define versioned_symbol(lib, local, symbol, version) \ |
74 | weak_alias (local, symbol) |
75 | |
76 | /* This should not appear outside `#if SHLIB_COMPAT (...)'. */ |
77 | # define compat_symbol(lib, local, symbol, version) ... |
78 | |
79 | #endif |
80 | |
81 | /* Use compat_symbol_reference for a reference to a specific version |
82 | of a symbol. Use compat_symbol to define such a symbol. */ |
83 | #define compat_symbol_reference(lib, local, symbol, version) \ |
84 | compat_symbol_reference_1 (lib, local, symbol, version) |
85 | #define compat_symbol_reference_1(lib, local, symbol, version) \ |
86 | compat_symbol_reference_2 (local, symbol, VERSION_##lib##_##version) |
87 | #define compat_symbol_reference_2(local, symbol, name) \ |
88 | symbol_version_reference (local, symbol, name) |
89 | |
90 | # ifdef LINK_OBSOLETE_RPC |
91 | /* Export the symbol for both static and dynamic linking. */ |
92 | # define libc_sunrpc_symbol(name, aliasname, version) \ |
93 | strong_alias (name, aliasname) |
94 | # else |
95 | /* Export the symbol only for shared-library compatibility. */ |
96 | # define libc_sunrpc_symbol(name, aliasname, version) \ |
97 | compat_symbol (libc, name, aliasname, version); |
98 | # endif |
99 | |
100 | #endif /* shlib-compat.h */ |
101 | |