sysdeps/unix/sysv/linux/init-first.c

   1 /* Initialization code run first thing by the ELF startup code.  Linux version.
   2 Copyright (C) 1995, 1996 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 The GNU C Library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <unistd.h>
  21 #include <sysdep.h>
  22 #include <fpu_control.h>
  23 #include <linux/personality.h>
  24 #include "init-first.h"
  25
  26 extern void __libc_init (int, char **, char **);
  27 extern void __libc_global_ctors (void);
  28
  29 /* The function is called from assembly stubs the compiler can't see.  */
  30 static void init (void *) __attribute__ ((unused));
  31
  32 extern int _dl_starting_up;
  33 weak_extern (_dl_starting_up)
  34
  35 /* Set nonzero if we have to be prepared for more then one libc being
  36    used in the process.  Safe assumption if initializer never runs.  */
  37 int __libc_multiple_libcs = 1;
  38
  39 static void
  40 init (void *data)
  41 {
  42   extern int __personality (int);
  43
  44   int argc = *(long *)data;
  45   char **argv = (char **)data + 1;
  46   char **envp = &argv[argc + 1];
  47
  48
  49   __libc_multiple_libcs = &_dl_starting_up && ! _dl_starting_up;
  50
  51   /* We must not call `personality' twice.  */
  52   if (!__libc_multiple_libcs)
  53     {
  54       /* The `personality' system call takes one argument that chooses
  55          the "personality", i.e. the set of system calls and such.  We
  56          must make this call first thing to disable emulation of some
  57          other system that might have been enabled by default based on
  58          the executable format.  */
  59       __personality (PER_LINUX);
  60
  61       /* Set the FPU control word to the proper default value.  */
  62       __setfpucw (__fpu_control);
  63     }
  64
  65   __environ = envp;
  66   __libc_init (argc, argv, envp);
  67
  68 #ifdef PIC
  69   __libc_global_ctors ();
  70 #endif
  71 }
  72
  73 #ifdef PIC
  74
  75 SYSDEP_CALL_INIT(_init, init);
  76
  77 void
  78 __libc_init_first (void)
  79 {
  80 }
  81
  82 #else
  83
  84 SYSDEP_CALL_INIT(__libc_init_first, init);
  85
  86 #endif