include/libc-symbols.h

   1 /* Support macros for making weak and strong aliases for symbols,
   2    and for using symbol sets and linker warnings with GNU ld.
   3    Copyright (C) 1995-1998,2000,2001,2002 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   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.
  10
  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
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #ifndef _LIBC_SYMBOLS_H
  22 #define _LIBC_SYMBOLS_H 1
  23
  24 /* This file's macros are included implicitly in the compilation of every
  25    file in the C library by -imacros.
  26
  27    We include config.h which is generated by configure.
  28    It should define for us the following symbols:
  29
  30    * HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
  31    * ASM_GLOBAL_DIRECTIVE with `.globl' or `.global'.
  32    * ASM_TYPE_DIRECTIVE_PREFIX with `@' or `#' or whatever for .type,
  33      or leave it undefined if there is no .type directive.
  34    * HAVE_GNU_LD if using GNU ld, with support for weak symbols in a.out,
  35    and for symbol set and warning messages extensions in a.out and ELF.
  36    * HAVE_ELF if using ELF, which supports weak symbols using `.weak'.
  37    * HAVE_ASM_WEAK_DIRECTIVE if we have weak symbols using `.weak'.
  38    * HAVE_ASM_WEAKEXT_DIRECTIVE if we have weak symbols using `.weakext'.
  39
  40    */
  41
  42 /* This is defined for the compilation of all C library code.  features.h
  43    tests this to avoid inclusion of stubs.h while compiling the library,
  44    before stubs.h has been generated.  Some library code that is shared
  45    with other packages also tests this symbol to see if it is being
  46    compiled as part of the C library.  We must define this before including
  47    config.h, because it makes some definitions conditional on whether libc
  48    itself is being compiled, or just some generator program.  */
  49 #define _LIBC   1
  50
  51 /* Enable declarations of GNU extensions, since we are compiling them.  */
  52 #define _GNU_SOURCE     1
  53 /* And we also need the data for the reentrant functions.  */
  54 #define _REENTRANT      1
  55
  56 #include <config.h>
  57
  58 /* The symbols in all the user (non-_) macros are C symbols.
  59    HAVE_GNU_LD without HAVE_ELF implies a.out.  */
  60
  61 #if defined HAVE_ASM_WEAK_DIRECTIVE || defined HAVE_ASM_WEAKEXT_DIRECTIVE
  62 # define HAVE_WEAK_SYMBOLS
  63 #endif
  64
  65 #ifndef __SYMBOL_PREFIX
  66 # ifdef NO_UNDERSCORES
  67 #  define __SYMBOL_PREFIX
  68 # else
  69 #  define __SYMBOL_PREFIX "_"
  70 # endif
  71 #endif
  72
  73 #ifndef C_SYMBOL_NAME
  74 # ifdef NO_UNDERSCORES
  75 #  define C_SYMBOL_NAME(name) name
  76 # else
  77 #  define C_SYMBOL_NAME(name) _##name
  78 # endif
  79 #endif
  80
  81 #ifndef ASM_LINE_SEP
  82 # define ASM_LINE_SEP ;
  83 #endif
  84
  85 #ifdef HAVE_ASM_GLOBAL_DOT_NAME
  86 # ifndef C_SYMBOL_DOT_NAME
  87 #  if defined __GNUC__ && defined __GNUC_MINOR__ \
  88       && (__GNUC__ << 16) + __GNUC_MINOR__ >= (3 << 16) + 1
  89 #   define C_SYMBOL_DOT_NAME(name) .name
  90 #  else
  91 #   define C_SYMBOL_DOT_NAME(name) .##name
  92 #  endif
  93 # endif
  94 #endif
  95
  96 #ifndef __ASSEMBLER__
  97 /* GCC understands weak symbols and aliases; use its interface where
  98    possible, instead of embedded assembly language.  */
  99
 100 /* Define ALIASNAME as a strong alias for NAME.  */
 101 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
 102 # define _strong_alias(name, aliasname) \
 103   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 104
 105 /* This comes between the return type and function name in
 106    a function definition to make that definition weak.  */
 107 # define weak_function __attribute__ ((weak))
 108 # define weak_const_function __attribute__ ((weak, __const__))
 109
 110 # ifdef HAVE_WEAK_SYMBOLS
 111
 112 /* Define ALIASNAME as a weak alias for NAME.
 113    If weak aliases are not available, this defines a strong alias.  */
 114 #  define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 115 #  define _weak_alias(name, aliasname) \
 116   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 117
 118 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 119 #  define weak_extern(symbol) _weak_extern (symbol)
 120 #  ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
 121 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 122 #    define _weak_extern(symbol) \
 123         asm (".weakext " __SYMBOL_PREFIX #symbol "\n\t" \
 124              ".weakext ." __SYMBOL_PREFIX #symbol);
 125 #   else
 126 #    define _weak_extern(symbol) asm (".weakext " __SYMBOL_PREFIX #symbol);
 127 #   endif
 128 #  else
 129 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 130 #    define _weak_extern(symbol) \
 131         asm (".weak " __SYMBOL_PREFIX #symbol "\n\t"    \
 132              ".weak ." __SYMBOL_PREFIX #symbol);
 133 #   else
 134 #    define _weak_extern(symbol) asm (".weak " __SYMBOL_PREFIX #symbol);
 135 #   endif
 136 #  endif
 137
 138 # else
 139
 140 #  define weak_alias(name, aliasname) strong_alias(name, aliasname)
 141 #  define weak_extern(symbol) /* Nothing. */
 142
 143 # endif
 144
 145 #else /* __ASSEMBLER__ */
 146
 147 # ifdef HAVE_ASM_SET_DIRECTIVE
 148 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 149 #   define strong_alias(original, alias)                                \
 150   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 151   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original) ASM_LINE_SEP      \
 152   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP           \
 153   .set C_SYMBOL_DOT_NAME (alias),C_SYMBOL_DOT_NAME (original)
 154 #   define strong_data_alias(original, alias)                           \
 155   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 156   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 157 #  else
 158 #   define strong_alias(original, alias)                                \
 159   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 160   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 161 #   define strong_data_alias(original, alias) strong_alias(original, alias)
 162 #  endif
 163 # else
 164 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 165 #   define strong_alias(original, alias)                                \
 166   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 167   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP         \
 168   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP           \
 169   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 170 #   define strong_data_alias(original, alias)                           \
 171   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 172   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 173 #  else
 174 #   define strong_alias(original, alias)                                \
 175   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 176   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 177 #   define strong_data_alias(original, alias) strong_alias(original, alias)
 178 #  endif
 179 # endif
 180
 181 # ifdef HAVE_WEAK_SYMBOLS
 182 #  ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
 183 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 184 #    define weak_alias(original, alias)                                 \
 185   .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original) ASM_LINE_SEP \
 186   .weakext C_SYMBOL_DOT_NAME (alias), C_SYMBOL_DOT_NAME (original)
 187 #   else
 188 #    define weak_alias(original, alias)                                 \
 189   .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
 190 #   endif
 191 #   define weak_extern(symbol)                                          \
 192   .weakext C_SYMBOL_NAME (symbol)
 193
 194 #  else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
 195
 196 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 197 #    define weak_alias(original, alias)                                 \
 198   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 199   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP         \
 200   .weak C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP                          \
 201   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 202 #   else
 203 #    define weak_alias(original, alias)                                 \
 204   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 205   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 206 #   endif
 207
 208 #   define weak_extern(symbol)                                          \
 209   .weak C_SYMBOL_NAME (symbol)
 210
 211 #  endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
 212
 213 # else /* ! HAVE_WEAK_SYMBOLS */
 214
 215 #  define weak_alias(original, alias) strong_alias(original, alias)
 216 #  define weak_extern(symbol) /* Nothing */
 217 # endif /* ! HAVE_WEAK_SYMBOLS */
 218
 219 #endif /* __ASSEMBLER__ */
 220
 221 /* On some platforms we can make internal function calls (i.e., calls of
 222    functions not exported) a bit faster by using a different calling
 223    convention.  */
 224 #ifndef internal_function
 225 # define internal_function      /* empty */
 226 #endif
 227
 228 /* Prepare for the case that `__builtin_expect' is not available.  */
 229 #ifndef HAVE_BUILTIN_EXPECT
 230 # define __builtin_expect(expr, val) (expr)
 231 #endif
 232
 233 /* Determine the return address.  */
 234 #define RETURN_ADDRESS(nr) \
 235   __builtin_extract_return_addr (__builtin_return_address (nr))
 236
 237 /* When a reference to SYMBOL is encountered, the linker will emit a
 238    warning message MSG.  */
 239 #ifdef HAVE_GNU_LD
 240 # ifdef HAVE_ELF
 241
 242 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 243 #  ifdef HAVE_ASM_PREVIOUS_DIRECTIVE
 244 #   define __make_section_unallocated(section_string)   \
 245   asm (".section " section_string "\n\t.previous");
 246 #  elif defined HAVE_ASM_POPSECTION_DIRECTIVE
 247 #   define __make_section_unallocated(section_string)   \
 248   asm (".pushsection " section_string "\n\t.popsection");
 249 #  else
 250 #   define __make_section_unallocated(section_string)
 251 #  endif
 252
 253 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 254    section attributes on what looks like a comment to the assembler.  */
 255 #  ifdef HAVE_SECTION_QUOTES
 256 #   define link_warning(symbol, msg) \
 257   __make_section_unallocated (".gnu.warning." #symbol) \
 258   static const char __evoke_link_warning_##symbol[]     \
 259     __attribute__ ((unused, section (".gnu.warning." #symbol "\"\n\t#\""))) \
 260     = msg;
 261 #  else
 262 #   define link_warning(symbol, msg) \
 263   __make_section_unallocated (".gnu.warning." #symbol) \
 264   static const char __evoke_link_warning_##symbol[]     \
 265     __attribute__ ((unused, section (".gnu.warning." #symbol "\n\t#"))) = msg;
 266 #  endif
 267 # else /* Not ELF: a.out */
 268 #  ifdef HAVE_XCOFF
 269 /* XCOFF does not support .stabs.
 270    The native aix linker will remove the .stab and .stabstr sections
 271    The gnu linker will have a fatal error if there is a relocation for
 272    symbol in the .stab section.  Silently disable this macro.  */
 273 #   define link_warning(symbol, msg)
 274 #  else
 275 #   define link_warning(symbol, msg)            \
 276      asm (".stabs \"" msg "\",30,0,0,0\n\t"     \
 277           ".stabs \"" __SYMBOL_PREFIX #symbol "\",1,0,0,0\n");
 278 #  endif /* XCOFF */
 279 # endif
 280 #else
 281 /* We will never be heard; they will all die horribly.  */
 282 # define link_warning(symbol, msg)
 283 #endif
 284
 285 /* A canned warning for sysdeps/stub functions.  */
 286 #define stub_warning(name) \
 287   link_warning (name, \
 288                 "warning: " #name " is not implemented and will always fail")
 289
 290
 291 /* Declare SYMBOL to be TYPE (`function' or `object') and of SIZE bytes,
 292    when the assembler supports such declarations (such as in ELF).
 293    This is only necessary when defining something in assembly, or playing
 294    funny alias games where the size should be other than what the compiler
 295    thinks it is.  */
 296 #define declare_symbol(symbol, type, size) \
 297   declare_symbol_1 (symbol, type, size)
 298 #ifdef ASM_TYPE_DIRECTIVE_PREFIX
 299 # ifdef __ASSEMBLER__
 300 #  define declare_symbol_1(symbol, type, size) \
 301     .type C_SYMBOL_NAME (symbol), \
 302           declare_symbol_1_paste (ASM_TYPE_DIRECTIVE_PREFIX, type), size
 303 #  define declare_symbol_1_paste(a, b)  declare_symbol_1_paste_1 (a,b)
 304 #  define declare_symbol_1_paste_1(a,b) a##b
 305 # else /* Not __ASSEMBLER__.  */
 306 #  define declare_symbol_1(symbol, type, size) \
 307     asm (".type " __SYMBOL_PREFIX #symbol ", " \
 308          declare_symbol_1_stringify (ASM_TYPE_DIRECTIVE_PREFIX) #type \
 309          "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
 310 #  define declare_symbol_1_stringify(x) declare_symbol_1_stringify_1 (x)
 311 #  define declare_symbol_1_stringify_1(x) #x
 312 # endif /* __ASSEMBLER__ */
 313 #else
 314 # define declare_symbol_1(symbol, type, size) /* Nothing.  */
 315 #endif
 316
 317
 318 /*
 319 \f
 320 */
 321
 322 #ifdef HAVE_GNU_LD
 323
 324 /* Symbol set support macros.  */
 325
 326 # ifdef HAVE_ELF
 327
 328 /* Make SYMBOL, which is in the text segment, an element of SET.  */
 329 #  define text_set_element(set, symbol) _elf_set_element(set, symbol)
 330 /* Make SYMBOL, which is in the data segment, an element of SET.  */
 331 #  define data_set_element(set, symbol) _elf_set_element(set, symbol)
 332 /* Make SYMBOL, which is in the bss segment, an element of SET.  */
 333 #  define bss_set_element(set, symbol)  _elf_set_element(set, symbol)
 334
 335 /* These are all done the same way in ELF.
 336    There is a new section created for each set.  */
 337 #  ifdef SHARED
 338 /* When building a shared library, make the set section writable,
 339    because it will need to be relocated at run time anyway.  */
 340 #   define _elf_set_element(set, symbol) \
 341   static const void *__elf_set_##set##_element_##symbol##__ \
 342     __attribute__ ((unused, section (#set))) = &(symbol)
 343 #  else
 344 #   define _elf_set_element(set, symbol) \
 345   static const void *const __elf_set_##set##_element_##symbol##__ \
 346     __attribute__ ((unused, section (#set))) = &(symbol)
 347 #  endif
 348
 349 /* Define SET as a symbol set.  This may be required (it is in a.out) to
 350    be able to use the set's contents.  */
 351 #  define symbol_set_define(set)        symbol_set_declare(set)
 352
 353 /* Declare SET for use in this module, if defined in another module.  */
 354 #  define symbol_set_declare(set) \
 355   extern void *const __start_##set __attribute__ ((__weak__));          \
 356   extern void *const __stop_##set __attribute__ ((__weak__));           \
 357   weak_extern (__start_##set) weak_extern (__stop_##set)
 358
 359 /* Return a pointer (void *const *) to the first element of SET.  */
 360 #  define symbol_set_first_element(set) (&__start_##set)
 361
 362 /* Return true iff PTR (a void *const *) has been incremented
 363    past the last element in SET.  */
 364 #  define symbol_set_end_p(set, ptr)    ((ptr) >= &__stop_##set)
 365
 366 # else  /* Not ELF: a.out.  */
 367
 368 #  ifdef HAVE_XCOFF
 369 /* XCOFF does not support .stabs.
 370    The native aix linker will remove the .stab and .stabstr sections
 371    The gnu linker will have a fatal error if there is a relocation for
 372    symbol in the .stab section.  Silently disable these macros.  */
 373 #   define text_set_element(set, symbol)
 374 #   define data_set_element(set, symbol)
 375 #   define bss_set_element(set, symbol)
 376 #  else
 377 #   define text_set_element(set, symbol)        \
 378     asm (".stabs \"" __SYMBOL_PREFIX #set "\",23,0,0," __SYMBOL_PREFIX #symbol)
 379 #   define data_set_element(set, symbol)        \
 380     asm (".stabs \"" __SYMBOL_PREFIX #set "\",25,0,0," __SYMBOL_PREFIX #symbol)
 381 #   define bss_set_element(set, symbol) ?error Must use initialized data.
 382 #  endif /* XCOFF */
 383 #  define symbol_set_define(set)        void *const (set)[1];
 384 #  define symbol_set_declare(set)       extern void *const (set)[1];
 385
 386 #  define symbol_set_first_element(set) &(set)[1]
 387 #  define symbol_set_end_p(set, ptr)    (*(ptr) == 0)
 388
 389 # endif /* ELF.  */
 390 #else
 391 /* We cannot do anything in generial.  */
 392 # define text_set_element(set, symbol) asm ("")
 393 # define data_set_element(set, symbol) asm ("")
 394 # define bss_set_element(set, symbol) asm ("")
 395 # define symbol_set_define(set)         void *const (set)[1];
 396 # define symbol_set_declare(set)        extern void *const (set)[1];
 397
 398 # define symbol_set_first_element(set)  &(set)[1]
 399 # define symbol_set_end_p(set, ptr)     (*(ptr) == 0)
 400 #endif  /* Have GNU ld.  */
 401
 402 #if DO_VERSIONING
 403 # define symbol_version(real, name, version) \
 404      _symbol_version(real, name, version)
 405 # define default_symbol_version(real, name, version) \
 406      _default_symbol_version(real, name, version)
 407 # ifdef __ASSEMBLER__
 408 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 409 #   define _symbol_version(real, name, version) \
 410      .symver real, name##@##version ASM_LINE_SEP                        \
 411      .symver .##real, .##name##@##version
 412 #   define _default_symbol_version(real, name, version) \
 413      .symver real, name##@##@##version ASM_LINE_SEP                     \
 414      .symver .##real, .##name##@##@##version
 415 #  else
 416 #   define _symbol_version(real, name, version) \
 417      .symver real, name##@##version
 418 #   define _default_symbol_version(real, name, version) \
 419      .symver real, name##@##@##version
 420 #  endif
 421 # else
 422 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 423 #   define _symbol_version(real, name, version) \
 424      __asm__ (".symver " #real "," #name "@" #version "\n\t"    \
 425               ".symver ." #real ",." #name "@" #version)
 426 #   define _default_symbol_version(real, name, version) \
 427      __asm__ (".symver " #real "," #name "@@" #version "\n\t"   \
 428               ".symver ." #real ",." #name "@@" #version)
 429 #  else
 430 #   define _symbol_version(real, name, version) \
 431      __asm__ (".symver " #real "," #name "@" #version)
 432 #   define _default_symbol_version(real, name, version) \
 433      __asm__ (".symver " #real "," #name "@@" #version)
 434 #  endif
 435 # endif
 436 #else
 437 # define symbol_version(real, name, version)
 438 # define default_symbol_version(real, name, version) \
 439   strong_alias(real, name)
 440 #endif
 441
 442 #if defined HAVE_VISIBILITY_ATTRIBUTE && defined SHARED
 443 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 444 #else
 445 # define attribute_hidden
 446 #endif
 447
 448 /* Handling on non-exported internal names.  We have to do this only
 449    for shared code.  */
 450 #ifdef SHARED
 451 # define INTUSE(name) name##_internal
 452 # define INTDEF(name) strong_alias (name, name##_internal)
 453 # define INTVARDEF(name) \
 454   _INTVARDEF (name, name##_internal)
 455 # if defined HAVE_VISIBILITY_ATTRIBUTE
 456 #  define _INTVARDEF(name, aliasname) \
 457   extern __typeof (name) aliasname __attribute__ ((alias (#name), \
 458                                                    visibility ("hidden")));
 459 # else
 460 #  define _INTVARDEF(name, aliasname) \
 461   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 462 # endif
 463 # define INTDEF2(name, newname) strong_alias (name, newname##_internal)
 464 # define INTVARDEF2(name, newname) _INTVARDEF (name, newname##_internal)
 465 #else
 466 # define INTUSE(name) name
 467 # define INTDEF(name)
 468 # define INTVARDEF(name)
 469 # define INTDEF2(name, newname)
 470 # define INTVARDEF2(name, newname)
 471 #endif
 472
 473 /* The following macros are used for PLT bypassing within libc.so
 474    (and if needed other libraries similarly).
 475    First of all, you need to have the function prototyped somewhere,
 476    say in foo/foo.h:
 477
 478    int foo (int __bar);
 479
 480    If calls to foo within libc.so should always go to foo defined in libc.so,
 481    then in include/foo.h you add:
 482
 483    libc_hidden_proto (foo)
 484
 485    line and after the foo function definition:
 486
 487    int foo (int __bar)
 488    {
 489      return __bar;
 490    }
 491    libc_hidden_def (foo)
 492
 493    or
 494
 495    int foo (int __bar)
 496    {
 497      return __bar;
 498    }
 499    libc_hidden_weak (foo)
 500
 501    Simularly for global data. If references to foo within libc.so should
 502    always go to foo defined in libc.so, then in include/foo.h you add:
 503
 504    libc_hidden_proto (foo)
 505
 506    line and after foo's definition:
 507
 508    int foo = INITIAL_FOO_VALUE;
 509    libc_hidden_data_def (foo)
 510
 511    or
 512
 513    int foo = INITIAL_FOO_VALUE;
 514    libc_hidden_data_weak (foo)
 515
 516    If foo is normally just an alias (strong or weak) of some other function,
 517    you should use the normal strong_alias first, then add libc_hidden_def
 518    or libc_hidden_weak:
 519
 520    int baz (int __bar)
 521    {
 522      return __bar;
 523    }
 524    strong_alias (baz, foo)
 525    libc_hidden_weak (foo)
 526
 527    If the function should be internal to multiple objects, say ld.so and
 528    libc.so, the best way is to use:
 529
 530    #if !defined NOT_IN_libc || defined IS_IN_rtld
 531    hidden_proto (foo)
 532    #endif
 533
 534    in include/foo.h and the normal macros at all function definitions
 535    depending on what DSO they belong to.
 536
 537    If versioned_symbol macro is used to define foo,
 538    libc_hidden_ver macro should be used, as in:
 539
 540    int __real_foo (int __bar)
 541    {
 542      return __bar;
 543    }
 544    versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
 545    libc_hidden_ver (__real_foo, foo)  */
 546
 547 #if defined SHARED && defined DO_VERSIONING \
 548     && !defined HAVE_BROKEN_ALIAS_ATTRIBUTE && !defined NO_HIDDEN
 549 # ifndef __ASSEMBLER__
 550 #  if !defined HAVE_VISIBILITY_ATTRIBUTE \
 551       || defined HAVE_BROKEN_VISIBILITY_ATTRIBUTE
 552 #   define __hidden_proto_hiddenattr(attrs...)
 553 #  else
 554 #   define __hidden_proto_hiddenattr(attrs...) \
 555   __attribute__ ((visibility ("hidden"), ##attrs))
 556 #  endif
 557 #  define hidden_proto(name, attrs...) \
 558   __hidden_proto (name, __GI_##name, ##attrs)
 559 #  define __hidden_proto(name, internal, attrs...) \
 560   extern __typeof (name) internal; \
 561   extern __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
 562   __hidden_proto_hiddenattr (attrs);
 563 #  define __hidden_asmname(name) \
 564   __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
 565 #  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
 566 #  define __hidden_asmname2(prefix, name) #prefix name
 567 #  ifdef HAVE_ASM_SET_DIRECTIVE
 568 #   define __hidden_def1(original, alias)                       \
 569   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP       \
 570   .set C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
 571 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 572 #     define __hidden_dot_def1(original, alias)  ASM_LINE_SEP   \
 573   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP   \
 574   .set C_SYMBOL_DOT_NAME (alias), C_SYMBOL_DOT_NAME (original)
 575 #   else
 576 #     define __hidden_dot_def1(original, alias)
 577 #   endif
 578 #  else
 579 #   define __hidden_def1(original, alias)                       \
 580   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP       \
 581   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 582 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 583 #    define __hidden_dot_def1(original, alias)  ASM_LINE_SEP    \
 584   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP   \
 585   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 586 #   else
 587 #    define __hidden_dot_def1(original, alias)
 588 #   endif
 589 #  endif
 590 #  define __hidden_def2(...) #__VA_ARGS__
 591 #  define __hidden_def3(...) __hidden_def2 (__VA_ARGS__)
 592 #  define hidden_def(name)                                      \
 593   __asm__ (__hidden_def3 (__hidden_def1 (__GI_##name, name) \
 594   __hidden_dot_def1 (__GI_##name, name)));
 595 #  define hidden_data_def(name)                                 \
 596   __asm__ (__hidden_def3 (__hidden_def1 (__GI_##name, name)));
 597 #  define hidden_ver(local, name)                               \
 598   __asm__ (__hidden_def3 (__hidden_def1 (local, __GI_##name) \
 599   __hidden_dot_def1 (local, __GI_##name)));
 600 #  define hidden_data_ver(local, name)                          \
 601   __asm__ (__hidden_def3 (__hidden_def1 (local, __GI_##name)));
 602 #  ifdef HAVE_WEAK_SYMBOLS
 603 #   ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
 604 #    define __hidden_weak1(original, alias)                     \
 605   .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
 606 #    ifdef HAVE_ASM_GLOBAL_DOT_NAME
 607 #     define __hidden_dot_weak1(original, alias)        ASM_LINE_SEP    \
 608   .weakext C_SYMBOL_DOT_NAME (alias), C_SYMBOL_DOT_NAME (original)
 609 #    else
 610 #     define __hidden_dot_weak1(original, alias)
 611 #    endif
 612 #   else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
 613 #    define __hidden_weak1(original, alias)                     \
 614   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                      \
 615   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 616 #    ifdef HAVE_ASM_GLOBAL_DOT_NAME
 617 #     define __hidden_dot_weak1(original, alias)        ASM_LINE_SEP    \
 618   .weak C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP  \
 619   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 620 #    else
 621 #     define __hidden_dot_weak1(original, alias)
 622 #    endif
 623 #   endif
 624 #   define hidden_weak(name)                                    \
 625   __asm__ (__hidden_def3 (__hidden_weak1 (__GI_##name, name) \
 626   __hidden_dot_weak1 (__GI_##name, name)));
 627 #   define hidden_data_weak(name)                                       \
 628   __asm__ (__hidden_def3 (__hidden_weak1 (__GI_##name, name)));
 629 #  else
 630 #   define hidden_weak(name) hidden_def (name)
 631 #  endif
 632 # else
 633 /* For assembly, we need to do the opposite of what we do in C:
 634    in assembly gcc __REDIRECT stuff is not in place, so functions
 635    are defined by its normal name and we need to create the
 636    __GI_* alias to it, in C __REDIRECT causes the function definition
 637    to use __GI_* name and we need to add alias to the real name.
 638    There is no reason to use hidden_weak over hidden_def in assembly,
 639    but we provide it for consistency with the C usage.
 640    hidden_proto doesn't make sense for assembly but the equivalent
 641    is to call via the HIDDEN_JUMPTARGET macro einstead of JUMPTARGET.  */
 642 #  define hidden_def(name)      strong_alias (name, __GI_##name)
 643 #  define hidden_weak(name)     hidden_def (name)
 644 #  define hidden_ver(local, name) strong_alias (local, __GI_##name)
 645 #  define hidden_data_def(name) strong_data_alias (name, __GI_##name)
 646 #  define hidden_data_weak(name)        hidden_data_def (name)
 647 #  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
 648 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 649 #   define HIDDEN_JUMPTARGET(name) .__GI_##name
 650 #  else
 651 #   define HIDDEN_JUMPTARGET(name) __GI_##name
 652 #  endif
 653 # endif
 654 #else
 655 # ifndef __ASSEMBLER__
 656 #  define hidden_proto(name, attrs...)
 657 # else
 658 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 659 # endif /* Not  __ASSEMBLER__ */
 660 # define hidden_weak(name)
 661 # define hidden_def(name)
 662 # define hidden_ver(local, name)
 663 # define hidden_data_weak(name)
 664 # define hidden_data_def(name)
 665 # define hidden_data_ver(local, name)
 666 #endif
 667
 668 #if !defined NOT_IN_libc
 669 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 670 # define libc_hidden_def(name) hidden_def (name)
 671 # define libc_hidden_weak(name) hidden_weak (name)
 672 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 673 # define libc_hidden_data_def(name) hidden_data_def (name)
 674 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 675 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 676 #else
 677 # define libc_hidden_proto(name, attrs...)
 678 # define libc_hidden_def(name)
 679 # define libc_hidden_weak(name)
 680 # define libc_hidden_ver(local, name)
 681 # define libc_hidden_data_def(name)
 682 # define libc_hidden_data_weak(name)
 683 # define libc_hidden_data_ver(local, name)
 684 #endif
 685
 686 #if defined NOT_IN_libc && defined IS_IN_rtld
 687 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 688 # define rtld_hidden_def(name) hidden_def (name)
 689 # define rtld_hidden_weak(name) hidden_weak (name)
 690 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 691 # define rtld_hidden_data_def(name) hidden_data_def (name)
 692 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 693 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 694 #else
 695 # define rtld_hidden_proto(name, attrs...)
 696 # define rtld_hidden_def(name)
 697 # define rtld_hidden_weak(name)
 698 # define rtld_hidden_ver(local, name)
 699 # define rtld_hidden_data_def(name)
 700 # define rtld_hidden_data_weak(name)
 701 # define rtld_hidden_data_ver(local, name)
 702 #endif
 703
 704 #if defined NOT_IN_libc && defined IS_IN_libm
 705 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 706 # define libm_hidden_def(name) hidden_def (name)
 707 # define libm_hidden_weak(name) hidden_weak (name)
 708 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 709 # define libm_hidden_data_def(name) hidden_data_def (name)
 710 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 711 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 712 #else
 713 # define libm_hidden_proto(name, attrs...)
 714 # define libm_hidden_def(name)
 715 # define libm_hidden_weak(name)
 716 # define libm_hidden_ver(local, name)
 717 # define libm_hidden_data_def(name)
 718 # define libm_hidden_data_weak(name)
 719 # define libm_hidden_data_ver(local, name)
 720 #endif
 721
 722 #endif /* libc-symbols.h */