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28f540f4 RM |
1 | /* Support macros for making weak and strong aliases for symbols, |
2 | and for using symbol sets and linker warnings with GNU ld. | |
dff8da6b | 3 | Copyright (C) 1995-2024 Free Software Foundation, Inc. |
5290baf0 | 4 | This file is part of the GNU C Library. |
28f540f4 | 5 | |
5290baf0 | 6 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
28f540f4 | 10 | |
5290baf0 UD |
11 | The GNU C Library is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
28f540f4 | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
28f540f4 RM |
19 | |
20 | #ifndef _LIBC_SYMBOLS_H | |
5290baf0 | 21 | #define _LIBC_SYMBOLS_H 1 |
28f540f4 | 22 | |
7c3018f9 ZW |
23 | /* This file is included implicitly in the compilation of every source file, |
24 | using -include. It includes config.h. */ | |
9cd47470 | 25 | |
7c3018f9 ZW |
26 | /* Enable declarations of GNU extensions, since we are compiling them. */ |
27 | #define _GNU_SOURCE 1 | |
28 | ||
29 | #ifdef MODULE_NAME | |
30 | ||
31 | /* Use `#if IS_IN (module)` to detect what component is being compiled. */ | |
32 | #define PASTE_NAME1(a,b) a##b | |
33 | #define PASTE_NAME(a,b) PASTE_NAME1 (a,b) | |
34 | #define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME) | |
35 | #define IS_IN(lib) (IN_MODULE == MODULE_##lib) | |
36 | ||
37 | /* True if the current module is a versioned library. Versioned | |
38 | library names culled from shlib-versions files are assigned a | |
39 | MODULE_* value greater than MODULE_LIBS_BEGIN. */ | |
40 | #define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN) | |
41 | ||
42 | /* The testsuite, and some other ancillary code, should be compiled against | |
43 | as close an approximation to the installed headers as possible. | |
44 | Defining this symbol disables most internal-use-only declarations | |
45 | provided by this header, and all those provided by other internal | |
46 | wrapper headers. */ | |
47 | #if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus | |
48 | # define _ISOMAC 1 | |
49 | #endif | |
28f540f4 | 50 | |
7c3018f9 ZW |
51 | #else |
52 | /* The generation process for a few files created very early in the | |
53 | build (notably libc-modules.h itself) involves preprocessing this | |
54 | header without defining MODULE_NAME. Under these conditions, | |
55 | internal declarations (especially from config.h) must be visible, | |
56 | but IS_IN should always evaluate as false. */ | |
57 | # define IS_IN(lib) 0 | |
58 | # define IS_IN_LIB 0 | |
59 | # define IN_MODULE (-1) | |
60 | #endif | |
28f540f4 | 61 | |
7c3018f9 | 62 | #ifndef _ISOMAC |
28f540f4 | 63 | |
92777700 RM |
64 | /* This is defined for the compilation of all C library code. features.h |
65 | tests this to avoid inclusion of stubs.h while compiling the library, | |
66 | before stubs.h has been generated. Some library code that is shared | |
67 | with other packages also tests this symbol to see if it is being | |
68 | compiled as part of the C library. We must define this before including | |
69 | config.h, because it makes some definitions conditional on whether libc | |
70 | itself is being compiled, or just some generator program. */ | |
c709e372 | 71 | #define _LIBC 1 |
92777700 | 72 | |
7c3018f9 ZW |
73 | /* Some files must be compiled with optimization on. */ |
74 | #if !defined __ASSEMBLER__ && !defined __OPTIMIZE__ | |
75 | # error "glibc cannot be compiled without optimization" | |
76 | #endif | |
77 | ||
78 | /* -ffast-math cannot be applied to the C library, as it alters the ABI. | |
79 | Some test components that use -ffast-math are currently not part of | |
80 | IS_IN (testsuite) for technical reasons, so we have a secondary override. */ | |
81 | #if defined __FAST_MATH__ && !defined TEST_FAST_MATH | |
82 | # error "glibc must not be compiled with -ffast-math" | |
83 | #endif | |
d3669add | 84 | |
92777700 | 85 | #include <config.h> |
28f540f4 | 86 | |
3a24ddea FW |
87 | /* Obtain the definition of symbol_version_reference. */ |
88 | #include <libc-symver.h> | |
89 | ||
086df229 L |
90 | /* When PIC is defined and SHARED isn't defined, we are building PIE |
91 | by default. */ | |
92 | #if defined PIC && !defined SHARED | |
93 | # define BUILD_PIE_DEFAULT 1 | |
94 | #else | |
95 | # define BUILD_PIE_DEFAULT 0 | |
96 | #endif | |
97 | ||
26ffd5e6 RM |
98 | /* Define this for the benefit of portable GNU code that wants to check it. |
99 | Code that checks with #if will not #include <config.h> again, since we've | |
100 | already done it (and this file is implicitly included in every compile, | |
101 | via -include). Code that checks with #ifdef will #include <config.h>, | |
102 | but that file should always be idempotent (i.e., it's just #define/#undef | |
103 | and nothing else anywhere should be changing the macro state it touches), | |
104 | so it's harmless. */ | |
105 | #define HAVE_CONFIG_H 0 | |
106 | ||
3f3dd810 SP |
107 | /* Define these macros for the benefit of portable GNU code that wants to check |
108 | them. Of course, STDC_HEADERS is never false when building libc! */ | |
26ffd5e6 | 109 | #define STDC_HEADERS 1 |
3f3dd810 SP |
110 | #define HAVE_MBSTATE_T 1 |
111 | #define HAVE_MBSRTOWCS 1 | |
a476ac4b SP |
112 | #define HAVE_LIBINTL_H 1 |
113 | #define HAVE_WCTYPE_H 1 | |
114 | #define HAVE_ISWCTYPE 1 | |
115 | #define ENABLE_NLS 1 | |
26ffd5e6 | 116 | |
0269750c | 117 | /* The symbols in all the user (non-_) macros are C symbols. */ |
28f540f4 | 118 | |
28f540f4 | 119 | #ifndef __SYMBOL_PREFIX |
a0da5fe1 | 120 | # define __SYMBOL_PREFIX |
28f540f4 RM |
121 | #endif |
122 | ||
123 | #ifndef C_SYMBOL_NAME | |
a0da5fe1 | 124 | # define C_SYMBOL_NAME(name) name |
28f540f4 RM |
125 | #endif |
126 | ||
b15cb495 UD |
127 | #ifndef ASM_LINE_SEP |
128 | # define ASM_LINE_SEP ; | |
129 | #endif | |
130 | ||
1626a1cf MS |
131 | #ifndef __attribute_copy__ |
132 | /* Provide an empty definition when cdefs.h is not included. */ | |
133 | # define __attribute_copy__(arg) | |
134 | #endif | |
135 | ||
428383e8 UD |
136 | #ifndef __ASSEMBLER__ |
137 | /* GCC understands weak symbols and aliases; use its interface where | |
138 | possible, instead of embedded assembly language. */ | |
d02907df | 139 | |
428383e8 | 140 | /* Define ALIASNAME as a strong alias for NAME. */ |
c62f5cab GM |
141 | # define strong_alias(name, aliasname) _strong_alias(name, aliasname) |
142 | # define _strong_alias(name, aliasname) \ | |
1626a1cf MS |
143 | extern __typeof (name) aliasname __attribute__ ((alias (#name))) \ |
144 | __attribute_copy__ (name); | |
428383e8 UD |
145 | |
146 | /* This comes between the return type and function name in | |
147 | a function definition to make that definition weak. */ | |
148 | # define weak_function __attribute__ ((weak)) | |
149 | # define weak_const_function __attribute__ ((weak, __const__)) | |
150 | ||
428383e8 UD |
151 | /* Define ALIASNAME as a weak alias for NAME. |
152 | If weak aliases are not available, this defines a strong alias. */ | |
a0da5fe1 UD |
153 | # define weak_alias(name, aliasname) _weak_alias (name, aliasname) |
154 | # define _weak_alias(name, aliasname) \ | |
1626a1cf MS |
155 | extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) \ |
156 | __attribute_copy__ (name); | |
428383e8 UD |
157 | |
158 | /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */ | |
a0da5fe1 UD |
159 | # define weak_extern(symbol) _weak_extern (weak symbol) |
160 | # define _weak_extern(expr) _Pragma (#expr) | |
428383e8 | 161 | |
ef4f9764 FW |
162 | /* In shared builds, the expression call_function_static_weak |
163 | (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an | |
164 | identifier) unconditionally, with the (potentially empty) argument | |
165 | list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a | |
166 | definition, the function is invoked as before; if FUNCTION-SYMBOL | |
167 | is NULL, no call is performed. */ | |
168 | # ifdef SHARED | |
169 | # define call_function_static_weak(func, ...) func (__VA_ARGS__) | |
170 | # else /* !SHARED */ | |
171 | # define call_function_static_weak(func, ...) \ | |
172 | ({ \ | |
173 | extern __typeof__ (func) func weak_function; \ | |
174 | (func != NULL ? func (__VA_ARGS__) : (void)0); \ | |
175 | }) | |
176 | # endif | |
428383e8 UD |
177 | |
178 | #else /* __ASSEMBLER__ */ | |
179 | ||
180 | # ifdef HAVE_ASM_SET_DIRECTIVE | |
5ca10a0c | 181 | # define strong_alias(original, alias) \ |
7b8e0d49 | 182 | .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \ |
c843e065 | 183 | .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original) |
5ca10a0c | 184 | # define strong_data_alias(original, alias) strong_alias(original, alias) |
dfd2257a | 185 | # else |
5ca10a0c | 186 | # define strong_alias(original, alias) \ |
7b8e0d49 | 187 | .globl C_SYMBOL_NAME (alias) ASM_LINE_SEP \ |
c843e065 | 188 | C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) |
5ca10a0c | 189 | # define strong_data_alias(original, alias) strong_alias(original, alias) |
dfd2257a | 190 | # endif |
d02907df | 191 | |
210dd782 | 192 | # define weak_alias(original, alias) \ |
c843e065 | 193 | .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP \ |
28f540f4 | 194 | C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) |
e6964dd4 | 195 | |
210dd782 | 196 | # define weak_extern(symbol) \ |
af5b3bc3 | 197 | .weak C_SYMBOL_NAME (symbol) |
d02907df | 198 | |
428383e8 | 199 | #endif /* __ASSEMBLER__ */ |
958f803f | 200 | |
e862aada UD |
201 | /* Determine the return address. */ |
202 | #define RETURN_ADDRESS(nr) \ | |
203 | __builtin_extract_return_addr (__builtin_return_address (nr)) | |
204 | ||
44c8d1a2 RM |
205 | /* When a reference to SYMBOL is encountered, the linker will emit a |
206 | warning message MSG. */ | |
fd26970f | 207 | /* We want the .gnu.warning.SYMBOL section to be unallocated. */ |
75b0964b | 208 | #define __make_section_unallocated(section_string) \ |
b15cb495 | 209 | asm (".section " section_string "\n\t.previous"); |
fd26970f | 210 | |
b15cb495 UD |
211 | /* Tacking on "\n\t#" to the section name makes gcc put it's bogus |
212 | section attributes on what looks like a comment to the assembler. */ | |
0269750c UD |
213 | #ifdef HAVE_SECTION_QUOTES |
214 | # define __sec_comment "\"\n\t#\"" | |
215 | #else | |
216 | # define __sec_comment "\n\t#" | |
217 | #endif | |
218 | #define link_warning(symbol, msg) \ | |
e26dd47f | 219 | __make_section_unallocated (".gnu.warning." #symbol) \ |
44c8d1a2 | 220 | static const char __evoke_link_warning_##symbol[] \ |
6c5775c3 | 221 | __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \ |
c877418f | 222 | = msg; |
28f540f4 RM |
223 | |
224 | /* A canned warning for sysdeps/stub functions. */ | |
225 | #define stub_warning(name) \ | |
561bcb80 | 226 | __make_section_unallocated (".gnu.glibc-stub." #name) \ |
cd525923 | 227 | link_warning (name, #name " is not implemented and will always fail") |
5f9e57ba | 228 | |
2f7f7bc6 UD |
229 | /* Warning for linking functions calling dlopen into static binaries. */ |
230 | #ifdef SHARED | |
231 | #define static_link_warning(name) | |
232 | #else | |
233 | #define static_link_warning(name) static_link_warning1(name) | |
234 | #define static_link_warning1(name) \ | |
235 | link_warning(name, "Using '" #name "' in statically linked applications \ | |
236 | requires at runtime the shared libraries from the glibc version used \ | |
237 | for linking") | |
238 | #endif | |
b88ac073 | 239 | |
11bf311e UD |
240 | /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes |
241 | alias to ORIGINAL, when the assembler supports such declarations | |
242 | (such as in ELF). | |
b88ac073 RM |
243 | This is only necessary when defining something in assembly, or playing |
244 | funny alias games where the size should be other than what the compiler | |
245 | thinks it is. */ | |
3020f726 | 246 | #define declare_object_symbol_alias(symbol, original, size) \ |
111254f3 | 247 | declare_object_symbol_alias_1 (symbol, original, size) |
3020f726 | 248 | #ifdef __ASSEMBLER__ |
111254f3 L |
249 | # define declare_object_symbol_alias_1(symbol, original, s_size) \ |
250 | strong_alias (original, symbol) ASM_LINE_SEP \ | |
251 | .type C_SYMBOL_NAME (symbol), %object ASM_LINE_SEP \ | |
252 | .size C_SYMBOL_NAME (symbol), s_size ASM_LINE_SEP | |
b67e9372 | 253 | #else /* Not __ASSEMBLER__. */ |
b67e9372 | 254 | # ifdef HAVE_ASM_SET_DIRECTIVE |
3020f726 AZN |
255 | # define declare_object_symbol_alias_1(symbol, original, size) \ |
256 | asm (".global " __SYMBOL_PREFIX # symbol "\n" \ | |
257 | ".type " __SYMBOL_PREFIX # symbol ", %object\n" \ | |
258 | ".set " __SYMBOL_PREFIX #symbol ", " __SYMBOL_PREFIX original "\n" \ | |
259 | ".size " __SYMBOL_PREFIX #symbol ", " #size "\n"); | |
b67e9372 | 260 | # else |
3020f726 AZN |
261 | # define declare_object_symbol_alias_1(symbol, original, size) \ |
262 | asm (".global " __SYMBOL_PREFIX # symbol "\n" \ | |
263 | ".type " __SYMBOL_PREFIX # symbol ", %object\n" \ | |
264 | __SYMBOL_PREFIX #symbol " = " __SYMBOL_PREFIX original "\n" \ | |
265 | ".size " __SYMBOL_PREFIX #symbol ", " #size "\n"); | |
b67e9372 MP |
266 | # endif /* HAVE_ASM_SET_DIRECTIVE */ |
267 | #endif /* __ASSEMBLER__ */ | |
b88ac073 RM |
268 | |
269 | ||
5f9e57ba | 270 | /* |
28f540f4 | 271 | \f |
5f9e57ba RM |
272 | */ |
273 | ||
cd6ae7ea FS |
274 | #ifdef HAVE_GNU_RETAIN |
275 | # define attribute_used_retain __attribute__ ((__used__, __retain__)) | |
276 | #else | |
277 | # define attribute_used_retain __attribute__ ((__used__)) | |
278 | #endif | |
279 | ||
28f540f4 RM |
280 | /* Symbol set support macros. */ |
281 | ||
28f540f4 | 282 | /* Make SYMBOL, which is in the text segment, an element of SET. */ |
0269750c | 283 | #define text_set_element(set, symbol) _elf_set_element(set, symbol) |
28f540f4 | 284 | /* Make SYMBOL, which is in the data segment, an element of SET. */ |
0269750c | 285 | #define data_set_element(set, symbol) _elf_set_element(set, symbol) |
28f540f4 | 286 | /* Make SYMBOL, which is in the bss segment, an element of SET. */ |
0269750c | 287 | #define bss_set_element(set, symbol) _elf_set_element(set, symbol) |
28f540f4 RM |
288 | |
289 | /* These are all done the same way in ELF. | |
290 | There is a new section created for each set. */ | |
0269750c | 291 | #ifdef SHARED |
53afa8d9 RM |
292 | /* When building a shared library, make the set section writable, |
293 | because it will need to be relocated at run time anyway. */ | |
0269750c | 294 | # define _elf_set_element(set, symbol) \ |
cd6ae7ea FS |
295 | static const void *__elf_set_##set##_element_##symbol##__ \ |
296 | attribute_used_retain __attribute__ ((section (#set))) = &(symbol) | |
0269750c UD |
297 | #else |
298 | # define _elf_set_element(set, symbol) \ | |
cd6ae7ea FS |
299 | static const void *const __elf_set_##set##_element_##symbol##__ \ |
300 | attribute_used_retain __attribute__ ((section (#set))) = &(symbol) | |
0269750c | 301 | #endif |
28f540f4 RM |
302 | |
303 | /* Define SET as a symbol set. This may be required (it is in a.out) to | |
304 | be able to use the set's contents. */ | |
0269750c | 305 | #define symbol_set_define(set) symbol_set_declare(set) |
28f540f4 | 306 | |
20792f99 RM |
307 | /* Declare SET for use in this module, if defined in another module. |
308 | In a shared library, this is always local to that shared object. | |
309 | For static linking, the set might be wholly absent and so we use | |
310 | weak references. */ | |
0269750c | 311 | #define symbol_set_declare(set) \ |
6f1e513d RH |
312 | extern char const __start_##set[] __symbol_set_attribute; \ |
313 | extern char const __stop_##set[] __symbol_set_attribute; | |
0269750c UD |
314 | #ifdef SHARED |
315 | # define __symbol_set_attribute attribute_hidden | |
316 | #else | |
317 | # define __symbol_set_attribute __attribute__ ((weak)) | |
318 | #endif | |
28f540f4 RM |
319 | |
320 | /* Return a pointer (void *const *) to the first element of SET. */ | |
0269750c | 321 | #define symbol_set_first_element(set) ((void *const *) (&__start_##set)) |
28f540f4 RM |
322 | |
323 | /* Return true iff PTR (a void *const *) has been incremented | |
324 | past the last element in SET. */ | |
0269750c | 325 | #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set) |
28f540f4 | 326 | |
3f2e46a4 | 327 | #ifdef SHARED |
ebdf53a7 | 328 | # define symbol_version(real, name, version) \ |
968dc26d | 329 | symbol_version_reference(real, name, version) |
ebdf53a7 GM |
330 | # define default_symbol_version(real, name, version) \ |
331 | _default_symbol_version(real, name, version) | |
0923f74a | 332 | /* See <libc-symver.h>. */ |
ebdf53a7 | 333 | # ifdef __ASSEMBLER__ |
5ca10a0c | 334 | # define _default_symbol_version(real, name, version) \ |
0923f74a | 335 | _set_symbol_version (real, name@@version) |
da2d1bc5 | 336 | # else |
5ca10a0c | 337 | # define _default_symbol_version(real, name, version) \ |
0923f74a | 338 | _set_symbol_version (real, #name "@@" #version) |
da2d1bc5 | 339 | # endif |
3a0ecccb | 340 | |
7f0d9e61 | 341 | /* Evaluates to a string literal for VERSION in LIB. */ |
3a0ecccb FW |
342 | # define symbol_version_string(lib, version) \ |
343 | _symbol_version_stringify_1 (VERSION_##lib##_##version) | |
344 | # define _symbol_version_stringify_1(arg) _symbol_version_stringify_2 (arg) | |
345 | # define _symbol_version_stringify_2(arg) #arg | |
346 | ||
347 | #else /* !SHARED */ | |
1ea89a40 | 348 | # define symbol_version(real, name, version) |
da2d1bc5 UD |
349 | # define default_symbol_version(real, name, version) \ |
350 | strong_alias(real, name) | |
1ea89a40 UD |
351 | #endif |
352 | ||
df359a25 SN |
353 | #if defined SHARED || defined LIBC_NONSHARED \ |
354 | || (BUILD_PIE_DEFAULT && IS_IN (libc)) | |
e6caf4e1 UD |
355 | # define attribute_hidden __attribute__ ((visibility ("hidden"))) |
356 | #else | |
357 | # define attribute_hidden | |
358 | #endif | |
359 | ||
3ce1f295 | 360 | #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec"))) |
9b21e6bc | 361 | |
11bf311e | 362 | #define attribute_relro __attribute__ ((section (".data.rel.ro"))) |
392a6b52 | 363 | |
de659123 NA |
364 | |
365 | /* Used to disable stack protection in sensitive places, like ifunc | |
366 | resolvers and early static TLS init. */ | |
367 | #ifdef HAVE_CC_NO_STACK_PROTECTOR | |
368 | # define inhibit_stack_protector \ | |
369 | __attribute__ ((__optimize__ ("-fno-stack-protector"))) | |
370 | #else | |
371 | # define inhibit_stack_protector | |
372 | #endif | |
373 | ||
37ba7d66 UD |
374 | /* The following macros are used for PLT bypassing within libc.so |
375 | (and if needed other libraries similarly). | |
376 | First of all, you need to have the function prototyped somewhere, | |
377 | say in foo/foo.h: | |
378 | ||
379 | int foo (int __bar); | |
380 | ||
381 | If calls to foo within libc.so should always go to foo defined in libc.so, | |
382 | then in include/foo.h you add: | |
383 | ||
384 | libc_hidden_proto (foo) | |
385 | ||
386 | line and after the foo function definition: | |
387 | ||
388 | int foo (int __bar) | |
389 | { | |
390 | return __bar; | |
391 | } | |
392 | libc_hidden_def (foo) | |
393 | ||
394 | or | |
395 | ||
396 | int foo (int __bar) | |
397 | { | |
398 | return __bar; | |
399 | } | |
400 | libc_hidden_weak (foo) | |
401 | ||
5536dfcb | 402 | Similarly for global data. If references to foo within libc.so should |
c843e065 RM |
403 | always go to foo defined in libc.so, then in include/foo.h you add: |
404 | ||
405 | libc_hidden_proto (foo) | |
406 | ||
407 | line and after foo's definition: | |
408 | ||
409 | int foo = INITIAL_FOO_VALUE; | |
410 | libc_hidden_data_def (foo) | |
411 | ||
412 | or | |
413 | ||
414 | int foo = INITIAL_FOO_VALUE; | |
415 | libc_hidden_data_weak (foo) | |
416 | ||
5536dfcb | 417 | If foo is normally just an alias (strong or weak) to some other function, |
37ba7d66 UD |
418 | you should use the normal strong_alias first, then add libc_hidden_def |
419 | or libc_hidden_weak: | |
420 | ||
421 | int baz (int __bar) | |
422 | { | |
423 | return __bar; | |
424 | } | |
425 | strong_alias (baz, foo) | |
426 | libc_hidden_weak (foo) | |
427 | ||
428 | If the function should be internal to multiple objects, say ld.so and | |
429 | libc.so, the best way is to use: | |
430 | ||
9cd47470 | 431 | #if IS_IN (libc) || IS_IN (rtld) |
37ba7d66 UD |
432 | hidden_proto (foo) |
433 | #endif | |
434 | ||
435 | in include/foo.h and the normal macros at all function definitions | |
436 | depending on what DSO they belong to. | |
437 | ||
438 | If versioned_symbol macro is used to define foo, | |
439 | libc_hidden_ver macro should be used, as in: | |
440 | ||
441 | int __real_foo (int __bar) | |
442 | { | |
443 | return __bar; | |
444 | } | |
445 | versioned_symbol (libc, __real_foo, foo, GLIBC_2_1); | |
446 | libc_hidden_ver (__real_foo, foo) */ | |
447 | ||
3f2e46a4 | 448 | #if defined SHARED && !defined NO_HIDDEN |
37ba7d66 | 449 | # ifndef __ASSEMBLER__ |
11bf311e | 450 | # define __hidden_proto_hiddenattr(attrs...) \ |
81cb0d82 | 451 | __attribute__ ((visibility ("hidden"), ##attrs)) |
81cb0d82 | 452 | # define hidden_proto(name, attrs...) \ |
699df45b | 453 | __hidden_proto (name, , __GI_##name, ##attrs) |
baf2a265 AZ |
454 | # define hidden_proto_alias(name, alias, attrs...) \ |
455 | __hidden_proto_alias (name, , alias, ##attrs) | |
699df45b JM |
456 | # define hidden_tls_proto(name, attrs...) \ |
457 | __hidden_proto (name, __thread, __GI_##name, ##attrs) | |
458 | # define __hidden_proto(name, thread, internal, attrs...) \ | |
459 | extern thread __typeof (name) name __asm__ (__hidden_asmname (#internal)) \ | |
81cb0d82 | 460 | __hidden_proto_hiddenattr (attrs); |
baf2a265 AZ |
461 | # define __hidden_proto_alias(name, thread, internal, attrs...) \ |
462 | extern thread __typeof (name) internal __hidden_proto_hiddenattr (attrs); | |
37ba7d66 UD |
463 | # define __hidden_asmname(name) \ |
464 | __hidden_asmname1 (__USER_LABEL_PREFIX__, name) | |
465 | # define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name) | |
466 | # define __hidden_asmname2(prefix, name) #prefix name | |
61995d3e | 467 | # define __hidden_ver1(local, internal, name) \ |
9c4b457e JM |
468 | __hidden_ver2 (, local, internal, name) |
469 | # define __hidden_ver2(thread, local, internal, name) \ | |
470 | extern thread __typeof (name) __EI_##name \ | |
471 | __asm__(__hidden_asmname (#internal)); \ | |
472 | extern thread __typeof (name) __EI_##name \ | |
1626a1cf MS |
473 | __attribute__((alias (__hidden_asmname (#local)))) \ |
474 | __attribute_copy__ (name) | |
61995d3e | 475 | # define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name); |
61995d3e | 476 | # define hidden_def(name) __hidden_ver1(__GI_##name, name, name); |
baf2a265 AZ |
477 | # define hidden_def_alias(name, internal) \ |
478 | strong_alias (name, internal) | |
61995d3e | 479 | # define hidden_data_def(name) hidden_def(name) |
baf2a265 | 480 | # define hidden_data_def_alias(name, alias) hidden_def_alias(name, alias) |
9c4b457e JM |
481 | # define hidden_tls_def(name) \ |
482 | __hidden_ver2 (__thread, __GI_##name, name, name); | |
61995d3e RM |
483 | # define hidden_weak(name) \ |
484 | __hidden_ver1(__GI_##name, name, name) __attribute__((weak)); | |
485 | # define hidden_data_weak(name) hidden_weak(name) | |
7b57bfe5 UD |
486 | # define hidden_nolink(name, lib, version) \ |
487 | __hidden_nolink1 (__GI_##name, __EI_##name, name, VERSION_##lib##_##version) | |
488 | # define __hidden_nolink1(local, internal, name, version) \ | |
489 | __hidden_nolink2 (local, internal, name, version) | |
490 | # define __hidden_nolink2(local, internal, name, version) \ | |
1626a1cf MS |
491 | extern __typeof (name) internal __attribute__ ((alias (#local))) \ |
492 | __attribute_copy__ (name); \ | |
7b57bfe5 UD |
493 | __hidden_nolink3 (local, internal, #name "@" #version) |
494 | # define __hidden_nolink3(local, internal, vername) \ | |
495 | __asm__ (".symver " #internal ", " vername); | |
37ba7d66 UD |
496 | # else |
497 | /* For assembly, we need to do the opposite of what we do in C: | |
498 | in assembly gcc __REDIRECT stuff is not in place, so functions | |
499 | are defined by its normal name and we need to create the | |
500 | __GI_* alias to it, in C __REDIRECT causes the function definition | |
501 | to use __GI_* name and we need to add alias to the real name. | |
4547dee3 RM |
502 | There is no reason to use hidden_weak over hidden_def in assembly, |
503 | but we provide it for consistency with the C usage. | |
504 | hidden_proto doesn't make sense for assembly but the equivalent | |
dce8f2b6 | 505 | is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET. */ |
4547dee3 | 506 | # define hidden_def(name) strong_alias (name, __GI_##name) |
baf2a265 | 507 | # define hidden_def_alias(name, alias) strong_alias (name, alias) |
4547dee3 | 508 | # define hidden_weak(name) hidden_def (name) |
37ba7d66 | 509 | # define hidden_ver(local, name) strong_alias (local, __GI_##name) |
c843e065 | 510 | # define hidden_data_def(name) strong_data_alias (name, __GI_##name) |
baf2a265 | 511 | # define hidden_data_def_alias(name, alias) strong_data_alias (name, alias) |
9c4b457e | 512 | # define hidden_tls_def(name) hidden_data_def (name) |
c843e065 | 513 | # define hidden_data_weak(name) hidden_data_def (name) |
5ca10a0c | 514 | # define HIDDEN_JUMPTARGET(name) __GI_##name |
37ba7d66 UD |
515 | # endif |
516 | #else | |
4547dee3 | 517 | # ifndef __ASSEMBLER__ |
8d2ec553 | 518 | # if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \ |
ee417882 | 519 | && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \ |
8d2ec553 L |
520 | && !defined NO_HIDDEN |
521 | # define __hidden_proto_hiddenattr(attrs...) \ | |
522 | __attribute__ ((visibility ("hidden"), ##attrs)) | |
523 | # define hidden_proto(name, attrs...) \ | |
524 | __hidden_proto (name, , name, ##attrs) | |
baf2a265 AZ |
525 | # define hidden_proto_alias(name, alias, attrs...) \ |
526 | __hidden_proto_alias (name, , alias, ##attrs) | |
8d2ec553 L |
527 | # define hidden_tls_proto(name, attrs...) \ |
528 | __hidden_proto (name, __thread, name, ##attrs) | |
529 | # define __hidden_proto(name, thread, internal, attrs...) \ | |
530 | extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs); | |
baf2a265 AZ |
531 | # define __hidden_proto_alias(name, thread, internal, attrs...) \ |
532 | extern thread __typeof (name) internal __hidden_proto_hiddenattr (attrs); | |
8d2ec553 L |
533 | # else |
534 | # define hidden_proto(name, attrs...) | |
baf2a265 | 535 | # define hidden_proto_alias(name, alias, attrs...) |
8d2ec553 L |
536 | # define hidden_tls_proto(name, attrs...) |
537 | # endif | |
4547dee3 RM |
538 | # else |
539 | # define HIDDEN_JUMPTARGET(name) JUMPTARGET(name) | |
540 | # endif /* Not __ASSEMBLER__ */ | |
541 | # define hidden_weak(name) | |
37ba7d66 | 542 | # define hidden_def(name) |
baf2a265 | 543 | # define hidden_def_alias(name, alias) |
37ba7d66 | 544 | # define hidden_ver(local, name) |
c843e065 RM |
545 | # define hidden_data_weak(name) |
546 | # define hidden_data_def(name) | |
baf2a265 | 547 | # define hidden_data_def_alias(name, alias) |
9c4b457e | 548 | # define hidden_tls_def(name) |
1792c087 | 549 | # define hidden_nolink(name, lib, version) |
37ba7d66 UD |
550 | #endif |
551 | ||
4f41c682 | 552 | #if IS_IN (libc) |
81cb0d82 | 553 | # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
baf2a265 AZ |
554 | # define libc_hidden_proto_alias(name, alias, attrs...) \ |
555 | hidden_proto_alias (name, alias, ##attrs) | |
699df45b | 556 | # define libc_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs) |
37ba7d66 UD |
557 | # define libc_hidden_def(name) hidden_def (name) |
558 | # define libc_hidden_weak(name) hidden_weak (name) | |
5500cdba | 559 | # define libc_hidden_nolink_sunrpc(name, version) hidden_nolink (name, libc, version) |
37ba7d66 | 560 | # define libc_hidden_ver(local, name) hidden_ver (local, name) |
c843e065 | 561 | # define libc_hidden_data_def(name) hidden_data_def (name) |
baf2a265 | 562 | # define libc_hidden_data_def_alias(name, alias) hidden_data_def_alias (name, alias) |
9c4b457e | 563 | # define libc_hidden_tls_def(name) hidden_tls_def (name) |
c843e065 | 564 | # define libc_hidden_data_weak(name) hidden_data_weak (name) |
37ba7d66 | 565 | #else |
81cb0d82 | 566 | # define libc_hidden_proto(name, attrs...) |
baf2a265 | 567 | # define libc_hidden_proto_alias(name, alias, attrs...) |
699df45b | 568 | # define libc_hidden_tls_proto(name, attrs...) |
37ba7d66 UD |
569 | # define libc_hidden_def(name) |
570 | # define libc_hidden_weak(name) | |
571 | # define libc_hidden_ver(local, name) | |
c843e065 | 572 | # define libc_hidden_data_def(name) |
baf2a265 | 573 | # define libc_hidden_data_def_alias(name, alias) |
9c4b457e | 574 | # define libc_hidden_tls_def(name) |
c843e065 | 575 | # define libc_hidden_data_weak(name) |
37ba7d66 UD |
576 | #endif |
577 | ||
3d3316b1 | 578 | #if IS_IN (rtld) |
81cb0d82 | 579 | # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
37ba7d66 UD |
580 | # define rtld_hidden_def(name) hidden_def (name) |
581 | # define rtld_hidden_weak(name) hidden_weak (name) | |
c843e065 | 582 | # define rtld_hidden_data_def(name) hidden_data_def (name) |
37ba7d66 | 583 | #else |
81cb0d82 | 584 | # define rtld_hidden_proto(name, attrs...) |
37ba7d66 UD |
585 | # define rtld_hidden_def(name) |
586 | # define rtld_hidden_weak(name) | |
c843e065 | 587 | # define rtld_hidden_data_def(name) |
37ba7d66 UD |
588 | #endif |
589 | ||
9cd47470 | 590 | #if IS_IN (libm) |
81cb0d82 | 591 | # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
37ba7d66 UD |
592 | # define libm_hidden_def(name) hidden_def (name) |
593 | # define libm_hidden_weak(name) hidden_weak (name) | |
594 | # define libm_hidden_ver(local, name) hidden_ver (local, name) | |
595 | #else | |
81cb0d82 | 596 | # define libm_hidden_proto(name, attrs...) |
37ba7d66 UD |
597 | # define libm_hidden_def(name) |
598 | # define libm_hidden_weak(name) | |
599 | # define libm_hidden_ver(local, name) | |
600 | #endif | |
601 | ||
829a679f | 602 | #if IS_IN (libmvec) |
cc0d77ba | 603 | # define libmvec_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
829a679f | 604 | # define libmvec_hidden_def(name) hidden_def (name) |
829a679f | 605 | #else |
cc0d77ba | 606 | # define libmvec_hidden_proto(name, attrs...) |
829a679f | 607 | # define libmvec_hidden_def(name) |
829a679f AS |
608 | #endif |
609 | ||
9cd47470 | 610 | #if IS_IN (libresolv) |
6f9d8e68 UD |
611 | # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
612 | # define libresolv_hidden_def(name) hidden_def (name) | |
6f9d8e68 | 613 | # define libresolv_hidden_data_def(name) hidden_data_def (name) |
6f9d8e68 UD |
614 | #else |
615 | # define libresolv_hidden_proto(name, attrs...) | |
616 | # define libresolv_hidden_def(name) | |
6f9d8e68 | 617 | # define libresolv_hidden_data_def(name) |
6f9d8e68 UD |
618 | #endif |
619 | ||
e3022f4b FW |
620 | #if IS_IN (libpthread) |
621 | # define libpthread_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) | |
e3022f4b | 622 | # define libpthread_hidden_def(name) hidden_def (name) |
e3022f4b FW |
623 | #else |
624 | # define libpthread_hidden_proto(name, attrs...) | |
e3022f4b | 625 | # define libpthread_hidden_def(name) |
e3022f4b FW |
626 | #endif |
627 | ||
9cd47470 | 628 | #if IS_IN (librt) |
a9564ae9 | 629 | # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
a9564ae9 | 630 | # define librt_hidden_ver(local, name) hidden_ver (local, name) |
a9564ae9 UD |
631 | #else |
632 | # define librt_hidden_proto(name, attrs...) | |
a9564ae9 | 633 | # define librt_hidden_ver(local, name) |
5f21997b UD |
634 | #endif |
635 | ||
9cd47470 | 636 | #if IS_IN (libnsl) |
1d5cee23 | 637 | # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) |
ae7a94e5 | 638 | # define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version) |
1d5cee23 UD |
639 | #else |
640 | # define libnsl_hidden_proto(name, attrs...) | |
1d5cee23 UD |
641 | #endif |
642 | ||
3ce1f295 UD |
643 | #define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs) |
644 | #define libc_hidden_builtin_def(name) libc_hidden_def (name) | |
45ae17dd PM |
645 | |
646 | #define libc_hidden_ldbl_proto(name, attrs...) libc_hidden_proto (name, ##attrs) | |
3ce1f295 UD |
647 | #ifdef __ASSEMBLER__ |
648 | # define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name) | |
85dd1003 UD |
649 | #endif |
650 | ||
94551be9 LM |
651 | #if IS_IN (libanl) |
652 | # define libanl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs) | |
94551be9 LM |
653 | #else |
654 | # define libanl_hidden_proto(name, attrs...) | |
94551be9 LM |
655 | #endif |
656 | ||
b30542fb UD |
657 | /* Get some dirty hacks. */ |
658 | #include <symbol-hacks.h> | |
659 | ||
4a381a81 UD |
660 | /* Move compatibility symbols out of the way by placing them all in a |
661 | special section. */ | |
d3a4a571 UD |
662 | #ifndef __ASSEMBLER__ |
663 | # define attribute_compat_text_section \ | |
4a381a81 | 664 | __attribute__ ((section (".text.compat"))) |
d3a4a571 UD |
665 | #else |
666 | # define compat_text_section .section ".text.compat", "ax"; | |
d3a4a571 | 667 | #endif |
4a381a81 | 668 | |
00980d84 | 669 | /* Helper / base macros for indirect function symbols. */ |
a29bb320 | 670 | #define __ifunc_resolver(type_name, name, expr, init, classifier, ...) \ |
ee4e992e | 671 | classifier inhibit_stack_protector \ |
a29bb320 | 672 | __typeof (type_name) *name##_ifunc (__VA_ARGS__) \ |
425ce2ed | 673 | { \ |
00980d84 SL |
674 | init (); \ |
675 | __typeof (type_name) *res = expr; \ | |
425ce2ed | 676 | return res; \ |
00980d84 SL |
677 | } |
678 | ||
679 | #ifdef HAVE_GCC_IFUNC | |
a29bb320 | 680 | # define __ifunc_args(type_name, name, expr, init, ...) \ |
00980d84 SL |
681 | extern __typeof (type_name) name __attribute__ \ |
682 | ((ifunc (#name "_ifunc"))); \ | |
a29bb320 | 683 | __ifunc_resolver (type_name, name, expr, init, static, __VA_ARGS__) |
00980d84 | 684 | |
a29bb320 EG |
685 | # define __ifunc_args_hidden(type_name, name, expr, init, ...) \ |
686 | __ifunc_args (type_name, name, expr, init, __VA_ARGS__) | |
00980d84 SL |
687 | #else |
688 | /* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour | |
689 | as fallback. But keep in mind that the debug information for the ifunc | |
690 | resolver functions is not correct. It contains the ifunc'ed function as | |
691 | DW_AT_linkage_name. E.g. lldb uses this field and an inferior function | |
692 | call of the ifunc'ed function will fail due to "no matching function for | |
693 | call to ..." because the ifunc'ed function and the resolver function have | |
694 | different signatures. (Gcc support is disabled at least on a ppc64le | |
695 | Ubuntu 14.04 system.) */ | |
696 | ||
a29bb320 | 697 | # define __ifunc_args(type_name, name, expr, init, ...) \ |
00980d84 | 698 | extern __typeof (type_name) name; \ |
a29bb320 EG |
699 | __typeof (type_name) *name##_ifunc (__VA_ARGS__) __asm__ (#name); \ |
700 | __ifunc_resolver (type_name, name, expr, init, , __VA_ARGS__) \ | |
00980d84 SL |
701 | __asm__ (".type " #name ", %gnu_indirect_function"); |
702 | ||
a29bb320 | 703 | # define __ifunc_args_hidden(type_name, name, expr, init, ...) \ |
00980d84 | 704 | extern __typeof (type_name) __libc_##name; \ |
a29bb320 | 705 | __ifunc (type_name, __libc_##name, expr, __VA_ARGS__, init) \ |
00980d84 SL |
706 | strong_alias (__libc_##name, name); |
707 | #endif /* !HAVE_GCC_IFUNC */ | |
708 | ||
a29bb320 EG |
709 | #define __ifunc(type_name, name, expr, arg, init) \ |
710 | __ifunc_args (type_name, name, expr, init, arg) | |
711 | ||
712 | #define __ifunc_hidden(type_name, name, expr, arg, init) \ | |
713 | __ifunc_args_hidden (type_name, name, expr, init, arg) | |
714 | ||
00980d84 SL |
715 | /* The following macros are used for indirect function symbols in libc.so. |
716 | First of all, you need to have the function prototyped somewhere, | |
717 | say in foo.h: | |
718 | ||
719 | int foo (int __bar); | |
720 | ||
721 | If you have an implementation for foo which e.g. uses a special hardware | |
722 | feature which isn't available on all machines where this libc.so will be | |
7f0d9e61 | 723 | used but decidable if available at runtime e.g. via hwcaps, you can provide |
00980d84 SL |
724 | two or multiple implementations of foo: |
725 | ||
726 | int __foo_default (int __bar) | |
727 | { | |
728 | return __bar; | |
729 | } | |
730 | ||
731 | int __foo_special (int __bar) | |
732 | { | |
733 | return __bar; | |
734 | } | |
735 | ||
736 | If your function foo has no libc_hidden_proto (foo) defined for PLT | |
737 | bypassing, you can use: | |
738 | ||
739 | #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap); | |
740 | ||
741 | libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default); | |
742 | ||
743 | This will define a resolver function for foo which returns __foo_special or | |
744 | __foo_default depending on your specified expression. Please note that you | |
745 | have to define a macro function INIT_ARCH before using libc_ifunc macro as | |
746 | it is called by the resolver function before evaluating the specified | |
747 | expression. In this example it is used to prepare the hwcap variable. | |
748 | The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo | |
749 | from inside or outside of libc.so will be indirected by a PLT call. | |
750 | ||
751 | If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing | |
752 | and calls to foo within libc.so should always go to one specific | |
753 | implementation of foo e.g. __foo_default then you have to add: | |
754 | ||
755 | __hidden_ver1 (__foo_default, __GI_foo, __foo_default); | |
756 | ||
757 | or a tweaked definition of libc_hidden_def macro after the __foo_default | |
758 | function definition. Calls to foo within libc.so will always go directly to | |
759 | __foo_default. Calls to foo from outside libc.so will be indirected by a | |
760 | PLT call to ifunc'ed symbol foo which you have to define in a separate | |
761 | compile unit: | |
762 | ||
763 | #define foo __redirect_foo | |
764 | #include <foo.h> | |
765 | #undef foo | |
766 | ||
767 | extern __typeof (__redirect_foo) __foo_default attribute_hidden; | |
768 | extern __typeof (__redirect_foo) __foo_special attribute_hidden; | |
769 | ||
770 | libc_ifunc_redirected (__redirect_foo, foo, | |
771 | (hwcap & HWCAP_SPECIAL) | |
772 | ? __foo_special | |
773 | : __foo_default); | |
774 | ||
775 | This will define the ifunc'ed symbol foo like above. The redirection of foo | |
7f0d9e61 | 776 | in header file is needed to omit an additional definition of __GI_foo which |
00980d84 SL |
777 | would end in a linker error while linking libc.so. You have to specify |
778 | __redirect_foo as first parameter which is used within libc_ifunc_redirected | |
779 | macro in conjunction with typeof to define the ifunc'ed symbol foo. | |
780 | ||
781 | If your function foo has a libc_hidden_proto (foo) defined and calls to foo | |
782 | within or from outside libc.so should go via ifunc'ed symbol, then you have | |
783 | to use: | |
784 | ||
785 | libc_ifunc_hidden (foo, foo, | |
786 | (hwcap & HWCAP_SPECIAL) | |
787 | ? __foo_special | |
788 | : __foo_default); | |
789 | libc_hidden_def (foo) | |
790 | ||
791 | The first parameter foo of libc_ifunc_hidden macro is used in the same way | |
792 | as for libc_ifunc_redirected macro. */ | |
793 | ||
794 | #define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH) | |
795 | ||
796 | #define libc_ifunc_redirected(redirected_name, name, expr) \ | |
797 | __ifunc (redirected_name, name, expr, void, INIT_ARCH) | |
798 | ||
799 | #define libc_ifunc_hidden(redirected_name, name, expr) \ | |
800 | __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH) | |
425ce2ed | 801 | |
9a1d2d45 UD |
802 | /* The body of the function is supposed to use __get_cpu_features |
803 | which will, if necessary, initialize the data first. */ | |
00980d84 SL |
804 | #define libm_ifunc_init() |
805 | #define libm_ifunc(name, expr) \ | |
806 | __ifunc (name, name, expr, void, libm_ifunc_init) | |
9a1d2d45 | 807 | |
85c2e611 AZ |
808 | /* Add the compiler optimization to inhibit loop transformation to library |
809 | calls. This is used to avoid recursive calls in memset and memmove | |
810 | default implementations. */ | |
811 | #ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL | |
812 | # define inhibit_loop_to_libcall \ | |
813 | __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns"))) | |
814 | #else | |
815 | # define inhibit_loop_to_libcall | |
816 | #endif | |
0f3be872 ZW |
817 | \f |
818 | /* These macros facilitate sharing source files with gnulib. | |
819 | ||
820 | They are here instead of sys/cdefs.h because they should not be | |
821 | used in public header files. | |
822 | ||
823 | Their definitions should be kept consistent with the definitions in | |
824 | gnulib-common.m4, but it is not necessary to cater to old non-GCC | |
825 | compilers, since they will only be used while building glibc itself. | |
826 | (Note that _GNUC_PREREQ cannot be used in this file.) */ | |
827 | ||
828 | /* Define as a marker that can be attached to declarations that might not | |
829 | be used. This helps to reduce warnings, such as from | |
830 | GCC -Wunused-parameter. */ | |
831 | #if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7) | |
832 | # define _GL_UNUSED __attribute__ ((__unused__)) | |
833 | #else | |
834 | # define _GL_UNUSED | |
835 | #endif | |
836 | ||
837 | /* gcc supports the "unused" attribute on possibly unused labels, and | |
838 | g++ has since version 4.5. Note to support C++ as well as C, | |
839 | _GL_UNUSED_LABEL should be used with a trailing ; */ | |
840 | #if !defined __cplusplus || __GNUC__ > 4 \ | |
841 | || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5) | |
842 | # define _GL_UNUSED_LABEL _GL_UNUSED | |
843 | #else | |
844 | # define _GL_UNUSED_LABEL | |
845 | #endif | |
846 | ||
847 | /* The __pure__ attribute was added in gcc 2.96. */ | |
848 | #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96) | |
849 | # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__)) | |
850 | #else | |
851 | # define _GL_ATTRIBUTE_PURE /* empty */ | |
852 | #endif | |
853 | ||
854 | /* The __const__ attribute was added in gcc 2.95. */ | |
855 | #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95) | |
856 | # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__)) | |
857 | #else | |
858 | # define _GL_ATTRIBUTE_CONST /* empty */ | |
859 | #endif | |
85c2e611 | 860 | |
7c3018f9 | 861 | #endif /* !_ISOMAC */ |
28f540f4 | 862 | #endif /* libc-symbols.h */ |