csu/elf-init.c

   1 /* Startup support for ELF initializers/finalizers in the main executable.
   2    Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    In addition to the permissions in the GNU Lesser General Public
  11    License, the Free Software Foundation gives you unlimited
  12    permission to link the compiled version of this file with other
  13    programs, and to distribute those programs without any restriction
  14    coming from the use of this file. (The GNU Lesser General Public
  15    License restrictions do apply in other respects; for example, they
  16    cover modification of the file, and distribution when not linked
  17    into another program.)
  18
  19    Note that people who make modified versions of this file are not
  20    obligated to grant this special exception for their modified
  21    versions; it is their choice whether to do so. The GNU Lesser
  22    General Public License gives permission to release a modified
  23    version without this exception; this exception also makes it
  24    possible to release a modified version which carries forward this
  25    exception.
  26
  27    The GNU C Library is distributed in the hope that it will be useful,
  28    but WITHOUT ANY WARRANTY; without even the implied warranty of
  29    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  30    Lesser General Public License for more details.
  31
  32    You should have received a copy of the GNU Lesser General Public
  33    License along with the GNU C Library; if not, write to the Free
  34    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  35    02111-1307 USA.  */
  36
  37 #include <stddef.h>
  38
  39
  40 /* These magic symbols are provided by the linker.  */
  41 extern void (*__preinit_array_start []) (int, char **, char **)
  42   attribute_hidden;
  43 extern void (*__preinit_array_end []) (int, char **, char **)
  44   attribute_hidden;
  45 extern void (*__init_array_start []) (int, char **, char **)
  46   attribute_hidden;
  47 extern void (*__init_array_end []) (int, char **, char **)
  48   attribute_hidden;
  49 extern void (*__fini_array_start []) (void) attribute_hidden;
  50 extern void (*__fini_array_end []) (void) attribute_hidden;
  51
  52 #if defined HAVE_VISIBILITY_ATTRIBUTE \
  53     && (defined SHARED || defined LIBC_NONSHARED)
  54 # define hidden_undef_2(x) #x
  55 # define hidden_undef_1(x) hidden_undef_2 (x)
  56 # define hidden_undef(x) \
  57   __asm (hidden_undef_1 (ASM_GLOBAL_DIRECTIVE) " " #x); \
  58   __asm (".hidden " #x);
  59 #else
  60 # define hidden_undef(x)
  61 #endif
  62
  63 hidden_undef (__preinit_array_start)
  64 hidden_undef (__preinit_array_end)
  65 hidden_undef (__init_array_start)
  66 hidden_undef (__init_array_end)
  67 hidden_undef (__fini_array_start)
  68 hidden_undef (__fini_array_end)
  69
  70 /* These function symbols are provided for the .init/.fini section entry
  71    points automagically by the linker.  */
  72 extern void _init (void);
  73 extern void _fini (void);
  74
  75 /* These functions are passed to __libc_start_main by the startup code.
  76    These get statically linked into each program.  For dynamically linked
  77    programs, this module will come from libc_nonshared.a and differs from
  78    the libc.a module in that it doesn't call the preinit array.  */
  79
  80 void
  81 __libc_csu_init (int argc, char **argv, char **envp)
  82 {
  83   /* For dynamically linked executables the preinit array is executed by
  84      the dynamic linker (before initializing any shared object.  */
  85
  86 #ifndef LIBC_NONSHARED
  87   /* For static executables, preinit happens rights before init.  */
  88   {
  89     const size_t size = __preinit_array_end - __preinit_array_start;
  90     size_t i;
  91     for (i = 0; i < size; i++)
  92       (*__preinit_array_start [i]) (argc, argv, envp);
  93   }
  94 #endif
  95
  96   _init ();
  97
  98   const size_t size = __init_array_end - __init_array_start;
  99   for (size_t i = 0; i < size; i++)
 100       (*__init_array_start [i]) (argc, argv, envp);
 101 }
 102
 103 /* This function should not be used anymore.  We run the executable's
 104    destructor now just like any other.  We cannot remove the function,
 105    though.  */
 106 void
 107 __libc_csu_fini (void)
 108 {
 109 #ifndef LIBC_NONSHARED
 110   size_t i = __fini_array_end - __fini_array_start;
 111   while (i-- > 0)
 112     (*__fini_array_start [i]) ();
 113
 114   _fini ();
 115 #endif
 116 }