csu/elf-init.c

   1 /* Startup support for ELF initializers/finalizers in the main executable.
   2    Copyright (C) 2002,2003,2004,2005,2009,2011
   3         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    In addition to the permissions in the GNU Lesser General Public
  12    License, the Free Software Foundation gives you unlimited
  13    permission to link the compiled version of this file with other
  14    programs, and to distribute those programs without any restriction
  15    coming from the use of this file. (The GNU Lesser General Public
  16    License restrictions do apply in other respects; for example, they
  17    cover modification of the file, and distribution when not linked
  18    into another program.)
  19
  20    Note that people who make modified versions of this file are not
  21    obligated to grant this special exception for their modified
  22    versions; it is their choice whether to do so. The GNU Lesser
  23    General Public License gives permission to release a modified
  24    version without this exception; this exception also makes it
  25    possible to release a modified version which carries forward this
  26    exception.
  27
  28    The GNU C Library is distributed in the hope that it will be useful,
  29    but WITHOUT ANY WARRANTY; without even the implied warranty of
  30    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  31    Lesser General Public License for more details.
  32
  33    You should have received a copy of the GNU Lesser General Public
  34    License along with the GNU C Library; if not, write to the Free
  35    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  36    02111-1307 USA.  */
  37
  38 #include <stddef.h>
  39
  40 #if defined USE_MULTIARCH && !defined LIBC_NONSHARED
  41 # include <link.h>
  42 # include <dl-irel.h>
  43
  44 # ifdef ELF_MACHINE_IRELA
  45 extern const ElfW(Rela) __rela_iplt_start [];
  46 extern const ElfW(Rela) __rela_iplt_end [];
  47 # endif
  48
  49 # ifdef ELF_MACHINE_IREL
  50 extern const ElfW(Rel) __rel_iplt_start [];
  51 extern const ElfW(Rel) __rel_iplt_end [];
  52 # endif
  53 #endif  /* LIBC_NONSHARED */
  54
  55 /* These magic symbols are provided by the linker.  */
  56 extern void (*__preinit_array_start []) (int, char **, char **)
  57   attribute_hidden;
  58 extern void (*__preinit_array_end []) (int, char **, char **)
  59   attribute_hidden;
  60 extern void (*__init_array_start []) (int, char **, char **)
  61   attribute_hidden;
  62 extern void (*__init_array_end []) (int, char **, char **)
  63   attribute_hidden;
  64 extern void (*__fini_array_start []) (void) attribute_hidden;
  65 extern void (*__fini_array_end []) (void) attribute_hidden;
  66
  67
  68 /* These function symbols are provided for the .init/.fini section entry
  69    points automagically by the linker.  */
  70 extern void _init (void);
  71 extern void _fini (void);
  72
  73 /* These functions are passed to __libc_start_main by the startup code.
  74    These get statically linked into each program.  For dynamically linked
  75    programs, this module will come from libc_nonshared.a and differs from
  76    the libc.a module in that it doesn't call the preinit array and performs
  77    explicit IREL{,A} relocations.  */
  78
  79
  80 #ifndef LIBC_NONSHARED
  81 void
  82 __libc_csu_irel (void)
  83 {
  84 # ifdef USE_MULTIARCH
  85 #  ifdef ELF_MACHINE_IRELA
  86   {
  87     const size_t size = __rela_iplt_end - __rela_iplt_start;
  88     for (size_t i = 0; i < size; i++)
  89       elf_irela (&__rela_iplt_start [i]);
  90   }
  91 #  endif
  92
  93 #  ifdef ELF_MACHINE_IREL
  94   {
  95     const size_t size = __rel_iplt_end - __rel_iplt_start;
  96     for (size_t i = 0; i < size; i++)
  97       elf_irel (&__rel_iplt_start [i]);
  98   }
  99 #  endif
 100 # endif
 101 }
 102 #endif
 103
 104
 105 void
 106 __libc_csu_init (int argc, char **argv, char **envp)
 107 {
 108   /* For dynamically linked executables the preinit array is executed by
 109      the dynamic linker (before initializing any shared object).  */
 110
 111 #ifndef LIBC_NONSHARED
 112   /* For static executables, preinit happens right before init.  */
 113   {
 114     const size_t size = __preinit_array_end - __preinit_array_start;
 115     size_t i;
 116     for (i = 0; i < size; i++)
 117       (*__preinit_array_start [i]) (argc, argv, envp);
 118   }
 119 #endif
 120
 121   _init ();
 122
 123   const size_t size = __init_array_end - __init_array_start;
 124   for (size_t i = 0; i < size; i++)
 125       (*__init_array_start [i]) (argc, argv, envp);
 126 }
 127
 128 /* This function should not be used anymore.  We run the executable's
 129    destructor now just like any other.  We cannot remove the function,
 130    though.  */
 131 void
 132 __libc_csu_fini (void)
 133 {
 134 #ifndef LIBC_NONSHARED
 135   size_t i = __fini_array_end - __fini_array_start;
 136   while (i-- > 0)
 137     (*__fini_array_start [i]) ();
 138
 139   _fini ();
 140 #endif
 141 }