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) 1995-1998,2000-2003,2004, 2005 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_ELF if using ELF, which supports weak symbols using `.weak'.
  35    * HAVE_ASM_WEAK_DIRECTIVE if we have weak symbols using `.weak'.
  36    * HAVE_ASM_WEAKEXT_DIRECTIVE if we have weak symbols using `.weakext'.
  37
  38    */
  39
  40 /* This is defined for the compilation of all C library code.  features.h
  41    tests this to avoid inclusion of stubs.h while compiling the library,
  42    before stubs.h has been generated.  Some library code that is shared
  43    with other packages also tests this symbol to see if it is being
  44    compiled as part of the C library.  We must define this before including
  45    config.h, because it makes some definitions conditional on whether libc
  46    itself is being compiled, or just some generator program.  */
  47 #define _LIBC   1
  48
  49 /* Enable declarations of GNU extensions, since we are compiling them.  */
  50 #define _GNU_SOURCE     1
  51 /* And we also need the data for the reentrant functions.  */
  52 #define _REENTRANT      1
  53
  54 #include <config.h>
  55
  56 /* The symbols in all the user (non-_) macros are C symbols.
  57    NO HAVE_ELF implies a.out.  */
  58
  59 #if defined HAVE_ASM_WEAK_DIRECTIVE || defined HAVE_ASM_WEAKEXT_DIRECTIVE
  60 # define HAVE_WEAK_SYMBOLS
  61 #endif
  62
  63 #ifndef __SYMBOL_PREFIX
  64 # ifdef NO_UNDERSCORES
  65 #  define __SYMBOL_PREFIX
  66 # else
  67 #  define __SYMBOL_PREFIX "_"
  68 # endif
  69 #endif
  70
  71 #ifndef C_SYMBOL_NAME
  72 # ifdef NO_UNDERSCORES
  73 #  define C_SYMBOL_NAME(name) name
  74 # else
  75 #  define C_SYMBOL_NAME(name) _##name
  76 # endif
  77 #endif
  78
  79 #ifndef ASM_LINE_SEP
  80 # define ASM_LINE_SEP ;
  81 #endif
  82
  83 #ifdef HAVE_ASM_GLOBAL_DOT_NAME
  84 # ifndef C_SYMBOL_DOT_NAME
  85 #  if defined __GNUC__ && defined __GNUC_MINOR__ \
  86       && (__GNUC__ << 16) + __GNUC_MINOR__ >= (3 << 16) + 1
  87 #   define C_SYMBOL_DOT_NAME(name) .name
  88 #  else
  89 #   define C_SYMBOL_DOT_NAME(name) .##name
  90 #  endif
  91 # endif
  92 #endif
  93
  94 #ifndef __ASSEMBLER__
  95 /* GCC understands weak symbols and aliases; use its interface where
  96    possible, instead of embedded assembly language.  */
  97
  98 /* Define ALIASNAME as a strong alias for NAME.  */
  99 # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
 100 # define _strong_alias(name, aliasname) \
 101   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 102
 103 /* This comes between the return type and function name in
 104    a function definition to make that definition weak.  */
 105 # define weak_function __attribute__ ((weak))
 106 # define weak_const_function __attribute__ ((weak, __const__))
 107
 108 # ifdef HAVE_WEAK_SYMBOLS
 109
 110 /* Define ALIASNAME as a weak alias for NAME.
 111    If weak aliases are not available, this defines a strong alias.  */
 112 #  define weak_alias(name, aliasname) _weak_alias (name, aliasname)
 113 #  define _weak_alias(name, aliasname) \
 114   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
 115
 116 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 117 #  define weak_extern(symbol) _weak_extern (weak symbol)
 118 #  define _weak_extern(expr) _Pragma (#expr)
 119
 120 # else
 121
 122 #  define weak_alias(name, aliasname) strong_alias(name, aliasname)
 123 #  define weak_extern(symbol) /* Nothing. */
 124
 125 # endif
 126
 127 #else /* __ASSEMBLER__ */
 128
 129 # ifdef HAVE_ASM_SET_DIRECTIVE
 130 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 131 #   define strong_alias(original, alias)                                \
 132   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 133   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original) ASM_LINE_SEP      \
 134   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP           \
 135   .set C_SYMBOL_DOT_NAME (alias),C_SYMBOL_DOT_NAME (original)
 136 #   define strong_data_alias(original, alias)                           \
 137   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 138   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 139 #  else
 140 #   define strong_alias(original, alias)                                \
 141   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 142   .set C_SYMBOL_NAME (alias),C_SYMBOL_NAME (original)
 143 #   define strong_data_alias(original, alias) strong_alias(original, alias)
 144 #  endif
 145 # else
 146 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 147 #   define strong_alias(original, alias)                                \
 148   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 149   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP         \
 150   ASM_GLOBAL_DIRECTIVE C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP           \
 151   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 152 #   define strong_data_alias(original, alias)                           \
 153   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 154   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 155 #  else
 156 #   define strong_alias(original, alias)                                \
 157   ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (alias) ASM_LINE_SEP               \
 158   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 159 #   define strong_data_alias(original, alias) strong_alias(original, alias)
 160 #  endif
 161 # endif
 162
 163 # ifdef HAVE_WEAK_SYMBOLS
 164 #  ifdef HAVE_ASM_WEAKEXT_DIRECTIVE
 165 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 166 #    define weak_alias(original, alias)                                 \
 167   .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original) ASM_LINE_SEP \
 168   .weakext C_SYMBOL_DOT_NAME (alias), C_SYMBOL_DOT_NAME (original)
 169 #   else
 170 #    define weak_alias(original, alias)                                 \
 171   .weakext C_SYMBOL_NAME (alias), C_SYMBOL_NAME (original)
 172 #   endif
 173 #   define weak_extern(symbol)                                          \
 174   .weakext C_SYMBOL_NAME (symbol)
 175
 176 #  else /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
 177
 178 #   ifdef HAVE_ASM_GLOBAL_DOT_NAME
 179 #    define weak_alias(original, alias)                                 \
 180   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 181   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original) ASM_LINE_SEP         \
 182   .weak C_SYMBOL_DOT_NAME (alias) ASM_LINE_SEP                          \
 183   C_SYMBOL_DOT_NAME (alias) = C_SYMBOL_DOT_NAME (original)
 184 #   else
 185 #    define weak_alias(original, alias)                                 \
 186   .weak C_SYMBOL_NAME (alias) ASM_LINE_SEP                              \
 187   C_SYMBOL_NAME (alias) = C_SYMBOL_NAME (original)
 188 #   endif
 189
 190 #   define weak_extern(symbol)                                          \
 191   .weak C_SYMBOL_NAME (symbol)
 192
 193 #  endif /* ! HAVE_ASM_WEAKEXT_DIRECTIVE */
 194
 195 # else /* ! HAVE_WEAK_SYMBOLS */
 196
 197 #  define weak_alias(original, alias) strong_alias(original, alias)
 198 #  define weak_extern(symbol) /* Nothing */
 199 # endif /* ! HAVE_WEAK_SYMBOLS */
 200
 201 #endif /* __ASSEMBLER__ */
 202
 203 /* On some platforms we can make internal function calls (i.e., calls of
 204    functions not exported) a bit faster by using a different calling
 205    convention.  */
 206 #ifndef internal_function
 207 # define internal_function      /* empty */
 208 #endif
 209
 210 /* Prepare for the case that `__builtin_expect' is not available.  */
 211 #ifndef HAVE_BUILTIN_EXPECT
 212 # define __builtin_expect(expr, val) (expr)
 213 #endif
 214
 215 /* Determine the return address.  */
 216 #define RETURN_ADDRESS(nr) \
 217   __builtin_extract_return_addr (__builtin_return_address (nr))
 218
 219 /* When a reference to SYMBOL is encountered, the linker will emit a
 220    warning message MSG.  */
 221 #ifdef HAVE_ELF
 222
 223 /* We want the .gnu.warning.SYMBOL section to be unallocated.  */
 224 # ifdef HAVE_ASM_PREVIOUS_DIRECTIVE
 225 #  define __make_section_unallocated(section_string)    \
 226   asm (".section " section_string "\n\t.previous");
 227 # elif defined HAVE_ASM_POPSECTION_DIRECTIVE
 228 #  define __make_section_unallocated(section_string)    \
 229   asm (".pushsection " section_string "\n\t.popsection");
 230 # else
 231 #  define __make_section_unallocated(section_string)
 232 # endif
 233
 234 /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
 235    section attributes on what looks like a comment to the assembler.  */
 236 # ifdef HAVE_SECTION_QUOTES
 237 #  define __sec_comment "\"\n\t#\""
 238 # else
 239 #  define __sec_comment "\n\t#"
 240 # endif
 241 # define link_warning(symbol, msg) \
 242   __make_section_unallocated (".gnu.warning." #symbol) \
 243   static const char __evoke_link_warning_##symbol[]     \
 244     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
 245     = msg;
 246 # define libc_freeres_ptr(decl) \
 247   __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
 248   decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
 249 # define __libc_freeres_fn_section \
 250   __attribute__ ((section ("__libc_freeres_fn")))
 251 #else /* Not ELF: a.out */
 252 # ifdef HAVE_XCOFF
 253 /* XCOFF does not support .stabs.
 254    The native aix linker will remove the .stab and .stabstr sections
 255    The gnu linker will have a fatal error if there is a relocation for
 256    symbol in the .stab section.  Silently disable this macro.  */
 257 #  define link_warning(symbol, msg)
 258 # else
 259 #  define link_warning(symbol, msg)             \
 260      asm (".stabs \"" msg "\",30,0,0,0\n\t"     \
 261           ".stabs \"" __SYMBOL_PREFIX #symbol "\",1,0,0,0\n");
 262 # endif /* XCOFF */
 263 # define libc_freeres_ptr(decl) decl
 264 # define __libc_freeres_fn_section
 265 #endif
 266 #define libc_freeres_fn(name)   \
 267   static void name (void) __attribute_used__ __libc_freeres_fn_section; \
 268   text_set_element (__libc_subfreeres, name);                           \
 269   static void name (void)
 270
 271 /* A canned warning for sysdeps/stub functions.  */
 272 #define stub_warning(name) \
 273   __make_section_unallocated (".gnu.glibc-stub." #name) \
 274   link_warning (name, \
 275                 "warning: " #name " is not implemented and will always fail")
 276
 277 /* Warning for linking functions calling dlopen into static binaries.  */
 278 #ifdef SHARED
 279 #define static_link_warning(name)
 280 #else
 281 #define static_link_warning(name) static_link_warning1(name)
 282 #define static_link_warning1(name) \
 283   link_warning(name, "Using '" #name "' in statically linked applications \
 284 requires at runtime the shared libraries from the glibc version used \
 285 for linking")
 286 #endif
 287
 288 /* Declare SYMBOL to be TYPE (`function' or `object') and of SIZE bytes,
 289    when the assembler supports such declarations (such as in ELF).
 290    This is only necessary when defining something in assembly, or playing
 291    funny alias games where the size should be other than what the compiler
 292    thinks it is.  */
 293 #define declare_symbol(symbol, type, size) \
 294   declare_symbol_1 (symbol, type, size)
 295 #ifdef ASM_TYPE_DIRECTIVE_PREFIX
 296 # ifdef __ASSEMBLER__
 297 #  define declare_symbol_1(symbol, type, size) \
 298     .type C_SYMBOL_NAME (symbol), \
 299           declare_symbol_1_paste (ASM_TYPE_DIRECTIVE_PREFIX, type), size
 300 #  define declare_symbol_1_paste(a, b)  declare_symbol_1_paste_1 (a,b)
 301 #  define declare_symbol_1_paste_1(a,b) a##b
 302 # else /* Not __ASSEMBLER__.  */
 303 #  define declare_symbol_1(symbol, type, size) \
 304     asm (".type " __SYMBOL_PREFIX #symbol ", " \
 305          declare_symbol_1_stringify (ASM_TYPE_DIRECTIVE_PREFIX) #type \
 306          "\n\t.size " __SYMBOL_PREFIX #symbol ", " #size);
 307 #  define declare_symbol_1_stringify(x) declare_symbol_1_stringify_1 (x)
 308 #  define declare_symbol_1_stringify_1(x) #x
 309 # endif /* __ASSEMBLER__ */
 310 #else
 311 # define declare_symbol_1(symbol, type, size) /* Nothing.  */
 312 #endif
 313
 314
 315 /*
 316 \f
 317 */
 318
 319 /* Symbol set support macros.  */
 320
 321 #ifdef HAVE_ELF
 322
 323 /* Make SYMBOL, which is in the text segment, an element of SET.  */
 324 # define text_set_element(set, symbol)  _elf_set_element(set, symbol)
 325 /* Make SYMBOL, which is in the data segment, an element of SET.  */
 326 # define data_set_element(set, symbol)  _elf_set_element(set, symbol)
 327 /* Make SYMBOL, which is in the bss segment, an element of SET.  */
 328 # define bss_set_element(set, symbol)   _elf_set_element(set, symbol)
 329
 330 /* These are all done the same way in ELF.
 331    There is a new section created for each set.  */
 332 # ifdef SHARED
 333 /* When building a shared library, make the set section writable,
 334    because it will need to be relocated at run time anyway.  */
 335 #  define _elf_set_element(set, symbol) \
 336   static const void *__elf_set_##set##_element_##symbol##__ \
 337     __attribute__ ((used, section (#set))) = &(symbol)
 338 # else
 339 #  define _elf_set_element(set, symbol) \
 340   static const void *const __elf_set_##set##_element_##symbol##__ \
 341     __attribute__ ((used, section (#set))) = &(symbol)
 342 # endif
 343
 344 /* Define SET as a symbol set.  This may be required (it is in a.out) to
 345    be able to use the set's contents.  */
 346 # define symbol_set_define(set) symbol_set_declare(set)
 347
 348 /* Declare SET for use in this module, if defined in another module.
 349    In a shared library, this is always local to that shared object.
 350    For static linking, the set might be wholly absent and so we use
 351    weak references.  */
 352 # define symbol_set_declare(set) \
 353   extern char const __start_##set[] __symbol_set_attribute; \
 354   extern char const __stop_##set[] __symbol_set_attribute;
 355 # ifdef SHARED
 356 #  define __symbol_set_attribute attribute_hidden
 357 # else
 358 #  define __symbol_set_attribute __attribute__ ((weak))
 359 # endif
 360
 361 /* Return a pointer (void *const *) to the first element of SET.  */
 362 # define symbol_set_first_element(set)  ((void *const *) (&__start_##set))
 363
 364 /* Return true iff PTR (a void *const *) has been incremented
 365    past the last element in SET.  */
 366 # define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
 367
 368 #else   /* Not ELF: a.out.  */
 369
 370 # ifdef HAVE_XCOFF
 371 /* XCOFF does not support .stabs.
 372    The native aix linker will remove the .stab and .stabstr sections
 373    The gnu linker will have a fatal error if there is a relocation for
 374    symbol in the .stab section.  Silently disable these macros.  */
 375 #  define text_set_element(set, symbol)
 376 #  define data_set_element(set, symbol)
 377 #  define bss_set_element(set, symbol)
 378 # else
 379 #  define text_set_element(set, symbol) \
 380     asm (".stabs \"" __SYMBOL_PREFIX #set "\",23,0,0," __SYMBOL_PREFIX #symbol)
 381 #  define data_set_element(set, symbol) \
 382     asm (".stabs \"" __SYMBOL_PREFIX #set "\",25,0,0," __SYMBOL_PREFIX #symbol)
 383 #  define bss_set_element(set, symbol)  ?error Must use initialized data.
 384 # endif /* XCOFF */
 385 # define symbol_set_define(set) void *const (set)[1];
 386 # define symbol_set_declare(set)        extern void *const (set)[1];
 387
 388 # define symbol_set_first_element(set)  &(set)[1]
 389 # define symbol_set_end_p(set, ptr)     (*(ptr) == 0)
 390
 391 #endif  /* ELF.  */
 392
 393 #if DO_VERSIONING
 394 # define symbol_version(real, name, version) \
 395      _symbol_version(real, name, version)
 396 # define default_symbol_version(real, name, version) \
 397      _default_symbol_version(real, name, version)
 398 # ifdef __ASSEMBLER__
 399 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 400 #   define _symbol_version(real, name, version) \
 401      .symver real, name##@##version ASM_LINE_SEP                        \
 402      .symver C_SYMBOL_DOT_NAME(real), C_SYMBOL_DOT_NAME(name##@##version)
 403 #   define _default_symbol_version(real, name, version) \
 404      .symver real, name##@##@##version ASM_LINE_SEP                     \
 405      .symver C_SYMBOL_DOT_NAME(real), C_SYMBOL_DOT_NAME(name##@##@##version)
 406 #  else
 407 #   define _symbol_version(real, name, version) \
 408      .symver real, name##@##version
 409 #   define _default_symbol_version(real, name, version) \
 410      .symver real, name##@##@##version
 411 #  endif
 412 # else
 413 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 414 #   define _symbol_version(real, name, version) \
 415      __asm__ (".symver " #real "," #name "@" #version "\n\t"    \
 416               ".symver ." #real ",." #name "@" #version)
 417 #   define _default_symbol_version(real, name, version) \
 418      __asm__ (".symver " #real "," #name "@@" #version "\n\t"   \
 419               ".symver ." #real ",." #name "@@" #version)
 420 #  else
 421 #   define _symbol_version(real, name, version) \
 422      __asm__ (".symver " #real "," #name "@" #version)
 423 #   define _default_symbol_version(real, name, version) \
 424      __asm__ (".symver " #real "," #name "@@" #version)
 425 #  endif
 426 # endif
 427 #else
 428 # define symbol_version(real, name, version)
 429 # define default_symbol_version(real, name, version) \
 430   strong_alias(real, name)
 431 #endif
 432
 433 #if defined HAVE_VISIBILITY_ATTRIBUTE \
 434     && (defined SHARED || defined LIBC_NONSHARED)
 435 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 436 #else
 437 # define attribute_hidden
 438 #endif
 439
 440 #ifdef HAVE_TLS_MODEL_ATTRIBUTE
 441 # define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 442 #else
 443 # define attribute_tls_model_ie
 444 #endif
 445
 446 #ifdef HAVE_Z_RELRO
 447 # define attribute_relro __attribute__ ((section (".data.rel.ro")))
 448 #else
 449 # define attribute_relro
 450 #endif
 451
 452 /* Handling on non-exported internal names.  We have to do this only
 453    for shared code.  */
 454 #ifdef SHARED
 455 # define INTUSE(name) name##_internal
 456 # define INTDEF(name) strong_alias (name, name##_internal)
 457 # define INTVARDEF(name) \
 458   _INTVARDEF (name, name##_internal)
 459 # if defined HAVE_VISIBILITY_ATTRIBUTE
 460 #  define _INTVARDEF(name, aliasname) \
 461   extern __typeof (name) aliasname __attribute__ ((alias (#name), \
 462                                                    visibility ("hidden")));
 463 # else
 464 #  define _INTVARDEF(name, aliasname) \
 465   extern __typeof (name) aliasname __attribute__ ((alias (#name)));
 466 # endif
 467 # define INTDEF2(name, newname) strong_alias (name, newname##_internal)
 468 # define INTVARDEF2(name, newname) _INTVARDEF (name, newname##_internal)
 469 #else
 470 # define INTUSE(name) name
 471 # define INTDEF(name)
 472 # define INTVARDEF(name)
 473 # define INTDEF2(name, newname)
 474 # define INTVARDEF2(name, newname)
 475 #endif
 476
 477 /* The following macros are used for PLT bypassing within libc.so
 478    (and if needed other libraries similarly).
 479    First of all, you need to have the function prototyped somewhere,
 480    say in foo/foo.h:
 481
 482    int foo (int __bar);
 483
 484    If calls to foo within libc.so should always go to foo defined in libc.so,
 485    then in include/foo.h you add:
 486
 487    libc_hidden_proto (foo)
 488
 489    line and after the foo function definition:
 490
 491    int foo (int __bar)
 492    {
 493      return __bar;
 494    }
 495    libc_hidden_def (foo)
 496
 497    or
 498
 499    int foo (int __bar)
 500    {
 501      return __bar;
 502    }
 503    libc_hidden_weak (foo)
 504
 505    Simularly for global data. If references to foo within libc.so should
 506    always go to foo defined in libc.so, then in include/foo.h you add:
 507
 508    libc_hidden_proto (foo)
 509
 510    line and after foo's definition:
 511
 512    int foo = INITIAL_FOO_VALUE;
 513    libc_hidden_data_def (foo)
 514
 515    or
 516
 517    int foo = INITIAL_FOO_VALUE;
 518    libc_hidden_data_weak (foo)
 519
 520    If foo is normally just an alias (strong or weak) of some other function,
 521    you should use the normal strong_alias first, then add libc_hidden_def
 522    or libc_hidden_weak:
 523
 524    int baz (int __bar)
 525    {
 526      return __bar;
 527    }
 528    strong_alias (baz, foo)
 529    libc_hidden_weak (foo)
 530
 531    If the function should be internal to multiple objects, say ld.so and
 532    libc.so, the best way is to use:
 533
 534    #if !defined NOT_IN_libc || defined IS_IN_rtld
 535    hidden_proto (foo)
 536    #endif
 537
 538    in include/foo.h and the normal macros at all function definitions
 539    depending on what DSO they belong to.
 540
 541    If versioned_symbol macro is used to define foo,
 542    libc_hidden_ver macro should be used, as in:
 543
 544    int __real_foo (int __bar)
 545    {
 546      return __bar;
 547    }
 548    versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
 549    libc_hidden_ver (__real_foo, foo)  */
 550
 551 #if defined SHARED && defined DO_VERSIONING \
 552     && !defined HAVE_BROKEN_ALIAS_ATTRIBUTE && !defined NO_HIDDEN
 553 # ifndef __ASSEMBLER__
 554 #  if !defined HAVE_VISIBILITY_ATTRIBUTE \
 555       || defined HAVE_BROKEN_VISIBILITY_ATTRIBUTE
 556 #   define __hidden_proto_hiddenattr(attrs...)
 557 #  else
 558 #   define __hidden_proto_hiddenattr(attrs...) \
 559   __attribute__ ((visibility ("hidden"), ##attrs))
 560 #  endif
 561 #  define hidden_proto(name, attrs...) \
 562   __hidden_proto (name, __GI_##name, ##attrs)
 563 #  define __hidden_proto(name, internal, attrs...) \
 564   extern __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
 565   __hidden_proto_hiddenattr (attrs);
 566 #  define __hidden_asmname(name) \
 567   __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
 568 #  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
 569 #  define __hidden_asmname2(prefix, name) #prefix name
 570 #  define __hidden_ver1(local, internal, name) \
 571   extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
 572   extern __typeof (name) __EI_##name \
 573         __attribute__((alias (__hidden_asmname (#local))))
 574 #  define hidden_ver(local, name)       __hidden_ver1(local, __GI_##name, name);
 575 #  define hidden_data_ver(local, name)  hidden_ver(local, name)
 576 #  define hidden_def(name)              __hidden_ver1(__GI_##name, name, name);
 577 #  define hidden_data_def(name)         hidden_def(name)
 578 #  define hidden_weak(name) \
 579         __hidden_ver1(__GI_##name, name, name) __attribute__((weak));
 580 #  define hidden_data_weak(name)        hidden_weak(name)
 581 # else
 582 /* For assembly, we need to do the opposite of what we do in C:
 583    in assembly gcc __REDIRECT stuff is not in place, so functions
 584    are defined by its normal name and we need to create the
 585    __GI_* alias to it, in C __REDIRECT causes the function definition
 586    to use __GI_* name and we need to add alias to the real name.
 587    There is no reason to use hidden_weak over hidden_def in assembly,
 588    but we provide it for consistency with the C usage.
 589    hidden_proto doesn't make sense for assembly but the equivalent
 590    is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
 591 #  define hidden_def(name)      strong_alias (name, __GI_##name)
 592 #  define hidden_weak(name)     hidden_def (name)
 593 #  define hidden_ver(local, name) strong_alias (local, __GI_##name)
 594 #  define hidden_data_def(name) strong_data_alias (name, __GI_##name)
 595 #  define hidden_data_weak(name)        hidden_data_def (name)
 596 #  define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
 597 #  ifdef HAVE_ASM_GLOBAL_DOT_NAME
 598 #   define HIDDEN_JUMPTARGET(name) .__GI_##name
 599 #  else
 600 #   define HIDDEN_JUMPTARGET(name) __GI_##name
 601 #  endif
 602 # endif
 603 #else
 604 # ifndef __ASSEMBLER__
 605 #  define hidden_proto(name, attrs...)
 606 # else
 607 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 608 # endif /* Not  __ASSEMBLER__ */
 609 # define hidden_weak(name)
 610 # define hidden_def(name)
 611 # define hidden_ver(local, name)
 612 # define hidden_data_weak(name)
 613 # define hidden_data_def(name)
 614 # define hidden_data_ver(local, name)
 615 #endif
 616
 617 #if !defined NOT_IN_libc
 618 # define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 619 # define libc_hidden_def(name) hidden_def (name)
 620 # define libc_hidden_weak(name) hidden_weak (name)
 621 # define libc_hidden_ver(local, name) hidden_ver (local, name)
 622 # define libc_hidden_data_def(name) hidden_data_def (name)
 623 # define libc_hidden_data_weak(name) hidden_data_weak (name)
 624 # define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
 625 #else
 626 # define libc_hidden_proto(name, attrs...)
 627 # define libc_hidden_def(name)
 628 # define libc_hidden_weak(name)
 629 # define libc_hidden_ver(local, name)
 630 # define libc_hidden_data_def(name)
 631 # define libc_hidden_data_weak(name)
 632 # define libc_hidden_data_ver(local, name)
 633 #endif
 634
 635 #if defined NOT_IN_libc && defined IS_IN_rtld
 636 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 637 # define rtld_hidden_def(name) hidden_def (name)
 638 # define rtld_hidden_weak(name) hidden_weak (name)
 639 # define rtld_hidden_ver(local, name) hidden_ver (local, name)
 640 # define rtld_hidden_data_def(name) hidden_data_def (name)
 641 # define rtld_hidden_data_weak(name) hidden_data_weak (name)
 642 # define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
 643 #else
 644 # define rtld_hidden_proto(name, attrs...)
 645 # define rtld_hidden_def(name)
 646 # define rtld_hidden_weak(name)
 647 # define rtld_hidden_ver(local, name)
 648 # define rtld_hidden_data_def(name)
 649 # define rtld_hidden_data_weak(name)
 650 # define rtld_hidden_data_ver(local, name)
 651 #endif
 652
 653 #if defined NOT_IN_libc && defined IS_IN_libm
 654 # define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 655 # define libm_hidden_def(name) hidden_def (name)
 656 # define libm_hidden_weak(name) hidden_weak (name)
 657 # define libm_hidden_ver(local, name) hidden_ver (local, name)
 658 # define libm_hidden_data_def(name) hidden_data_def (name)
 659 # define libm_hidden_data_weak(name) hidden_data_weak (name)
 660 # define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
 661 #else
 662 # define libm_hidden_proto(name, attrs...)
 663 # define libm_hidden_def(name)
 664 # define libm_hidden_weak(name)
 665 # define libm_hidden_ver(local, name)
 666 # define libm_hidden_data_def(name)
 667 # define libm_hidden_data_weak(name)
 668 # define libm_hidden_data_ver(local, name)
 669 #endif
 670
 671 #if defined NOT_IN_libc && defined IS_IN_libresolv
 672 # define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 673 # define libresolv_hidden_def(name) hidden_def (name)
 674 # define libresolv_hidden_weak(name) hidden_weak (name)
 675 # define libresolv_hidden_ver(local, name) hidden_ver (local, name)
 676 # define libresolv_hidden_data_def(name) hidden_data_def (name)
 677 # define libresolv_hidden_data_weak(name) hidden_data_weak (name)
 678 # define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
 679 #else
 680 # define libresolv_hidden_proto(name, attrs...)
 681 # define libresolv_hidden_def(name)
 682 # define libresolv_hidden_weak(name)
 683 # define libresolv_hidden_ver(local, name)
 684 # define libresolv_hidden_data_def(name)
 685 # define libresolv_hidden_data_weak(name)
 686 # define libresolv_hidden_data_ver(local, name)
 687 #endif
 688
 689 #if defined NOT_IN_libc && defined IS_IN_librt
 690 # define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 691 # define librt_hidden_def(name) hidden_def (name)
 692 # define librt_hidden_weak(name) hidden_weak (name)
 693 # define librt_hidden_ver(local, name) hidden_ver (local, name)
 694 # define librt_hidden_data_def(name) hidden_data_def (name)
 695 # define librt_hidden_data_weak(name) hidden_data_weak (name)
 696 # define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
 697 #else
 698 # define librt_hidden_proto(name, attrs...)
 699 # define librt_hidden_def(name)
 700 # define librt_hidden_weak(name)
 701 # define librt_hidden_ver(local, name)
 702 # define librt_hidden_data_def(name)
 703 # define librt_hidden_data_weak(name)
 704 # define librt_hidden_data_ver(local, name)
 705 #endif
 706
 707 #if defined NOT_IN_libc && defined IS_IN_libdl
 708 # define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 709 # define libdl_hidden_def(name) hidden_def (name)
 710 # define libdl_hidden_weak(name) hidden_weak (name)
 711 # define libdl_hidden_ver(local, name) hidden_ver (local, name)
 712 # define libdl_hidden_data_def(name) hidden_data_def (name)
 713 # define libdl_hidden_data_weak(name) hidden_data_weak (name)
 714 # define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 715 #else
 716 # define libdl_hidden_proto(name, attrs...)
 717 # define libdl_hidden_def(name)
 718 # define libdl_hidden_weak(name)
 719 # define libdl_hidden_ver(local, name)
 720 # define libdl_hidden_data_def(name)
 721 # define libdl_hidden_data_weak(name)
 722 # define libdl_hidden_data_ver(local, name)
 723 #endif
 724
 725 #if defined NOT_IN_libc && defined IS_IN_libnss_files
 726 # define libnss_files_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 727 # define libnss_files_hidden_def(name) hidden_def (name)
 728 # define libnss_files_hidden_weak(name) hidden_weak (name)
 729 # define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
 730 # define libnss_files_hidden_data_def(name) hidden_data_def (name)
 731 # define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
 732 # define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
 733 #else
 734 # define libnss_files_hidden_proto(name, attrs...)
 735 # define libnss_files_hidden_def(name)
 736 # define libnss_files_hidden_weak(name)
 737 # define libnss_files_hidden_ver(local, name)
 738 # define libnss_files_hidden_data_def(name)
 739 # define libnss_files_hidden_data_weak(name)
 740 # define libnss_files_hidden_data_ver(local, name)
 741 #endif
 742
 743 #if defined NOT_IN_libc && defined IS_IN_libnsl
 744 # define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 745 # define libnsl_hidden_def(name) hidden_def (name)
 746 # define libnsl_hidden_weak(name) hidden_weak (name)
 747 # define libnsl_hidden_ver(local, name) hidden_ver (local, name)
 748 # define libnsl_hidden_data_def(name) hidden_data_def (name)
 749 # define libnsl_hidden_data_weak(name) hidden_data_weak (name)
 750 # define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
 751 #else
 752 # define libnsl_hidden_proto(name, attrs...)
 753 # define libnsl_hidden_def(name)
 754 # define libnsl_hidden_weak(name)
 755 # define libnsl_hidden_ver(local, name)
 756 # define libnsl_hidden_data_def(name)
 757 # define libnsl_hidden_data_weak(name)
 758 # define libnsl_hidden_data_ver(local, name)
 759 #endif
 760
 761 #if defined NOT_IN_libc && defined IS_IN_libnss_nisplus
 762 # define libnss_nisplus_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 763 # define libnss_nisplus_hidden_def(name) hidden_def (name)
 764 # define libnss_nisplus_hidden_weak(name) hidden_weak (name)
 765 # define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
 766 # define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
 767 # define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
 768 # define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
 769 #else
 770 # define libnss_nisplus_hidden_proto(name, attrs...)
 771 # define libnss_nisplus_hidden_def(name)
 772 # define libnss_nisplus_hidden_weak(name)
 773 # define libnss_nisplus_hidden_ver(local, name)
 774 # define libnss_nisplus_hidden_data_def(name)
 775 # define libnss_nisplus_hidden_data_weak(name)
 776 # define libnss_nisplus_hidden_data_ver(local, name)
 777 #endif
 778
 779 #ifdef HAVE_BUILTIN_REDIRECTION
 780 # define libc_hidden_builtin_proto(name, attrs...) libc_hidden_proto (name, ##attrs)
 781 # define libc_hidden_builtin_def(name) libc_hidden_def (name)
 782 # define libc_hidden_builtin_weak(name) libc_hidden_weak (name)
 783 # define libc_hidden_builtin_ver(local, name) libc_hidden_ver (local, name)
 784 # ifdef __ASSEMBLER__
 785 #  define HIDDEN_BUILTIN_JUMPTARGET(name) HIDDEN_JUMPTARGET(name)
 786 # endif
 787 #else
 788 # define libc_hidden_builtin_proto(name, attrs...)
 789 # define libc_hidden_builtin_def(name)
 790 # define libc_hidden_builtin_weak(name)
 791 # define libc_hidden_builtin_ver(local, name)
 792 # ifdef __ASSEMBLER__
 793 #  define HIDDEN_BUILTIN_JUMPTARGET(name) JUMPTARGET(name)
 794 # endif
 795 #endif
 796
 797 #if defined NOT_IN_libc && defined IS_IN_libutil
 798 # define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 799 # define libutil_hidden_def(name) hidden_def (name)
 800 # define libutil_hidden_weak(name) hidden_weak (name)
 801 # define libutil_hidden_ver(local, name) hidden_ver (local, name)
 802 # define libutil_hidden_data_def(name) hidden_data_def (name)
 803 # define libutil_hidden_data_weak(name) hidden_data_weak (name)
 804 # define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
 805 #else
 806 # define libutil_hidden_proto(name, attrs...)
 807 # define libutil_hidden_def(name)
 808 # define libutil_hidden_weak(name)
 809 # define libutil_hidden_ver(local, name)
 810 # define libutil_hidden_data_def(name)
 811 # define libutil_hidden_data_weak(name)
 812 # define libutil_hidden_data_ver(local, name)
 813 #endif
 814
 815 /* Get some dirty hacks.  */
 816 #include <symbol-hacks.h>
 817
 818 /* Move compatibility symbols out of the way by placing them all in a
 819    special section.  */
 820 #ifndef __ASSEMBLER__
 821 # define attribute_compat_text_section \
 822     __attribute__ ((section (".text.compat")))
 823 # define attribute_compat_data_section \
 824     __attribute__ ((section (".data.compat")))
 825 #else
 826 # define compat_text_section .section ".text.compat", "ax";
 827 # define compat_data_section .section ".data.compat", "aw";
 828 #endif
 829
 830 #endif /* libc-symbols.h */