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 /* Remember the command line argument and enviroment contents for
  40    later calls of initializers for dynamic libraries.  */
  41 int __libc_argc;
  42 char **__libc_argv;
  43 char **__libc_envp;
  44
  45
  46 static void
  47 init (void *data)
  48 {
  49   extern int __personality (int);
  50
  51   __libc_multiple_libcs = &_dl_starting_up && ! _dl_starting_up;
  52
  53
  54   /* We must not call `personality' twice.  */
  55   if (!__libc_multiple_libcs)
  56     {
  57       /* The argument we got points to the values describing the
  58          command line argument etc.  */
  59       __libc_argc = *(int *)data;
  60       __libc_argv = (char **)data + 1;
  61       __libc_envp = &__libc_argv[__libc_argc + 1];
  62
  63       /* The `personality' system call takes one argument that chooses
  64          the "personality", i.e. the set of system calls and such.  We
  65          must make this call first thing to disable emulation of some
  66          other system that might have been enabled by default based on
  67          the executable format.  */
  68       __personality (PER_LINUX);
  69
  70       /* Set the FPU control word to the proper default value.  */
  71       __setfpucw (__fpu_control);
  72     }
  73   else
  74     {
  75       /* The argument we got points to the values describing the
  76          command line argument etc.  */
  77       __libc_argc = *((int *)data)++;
  78       __libc_argv = *((char ***)data)++;
  79       __libc_envp = *(char ***)data;
  80     }
  81
  82   __environ = __libc_envp;
  83   __libc_init (__libc_argc, __libc_argv, __libc_envp);
  84
  85 #ifdef PIC
  86   __libc_global_ctors ();
  87 #endif
  88 }
  89
  90 #ifdef PIC
  91
  92 SYSDEP_CALL_INIT(_init, init);
  93
  94 void
  95 __libc_init_first (void)
  96 {
  97 }
  98
  99 #else
 100
 101 SYSDEP_CALL_INIT(__libc_init_first, init);
 102
 103 #endif