sysdeps/unix/start.c

   1 /* Copyright (C) 1991, 93, 95, 96, 97, 98 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <sysdep.h>             /* In case it wants to define anything.  */
  23
  24 /* The first piece of initialized data.  */
  25 int __data_start = 0;
  26 #ifdef HAVE_WEAK_SYMBOLS
  27 weak_alias (__data_start, data_start)
  28 #endif
  29
  30 #ifdef  DUMMIES
  31 #define ARG_DUMMIES     DUMMIES,
  32 #define DECL_DUMMIES    int DUMMIES;
  33 #else
  34 #define ARG_DUMMIES
  35 #define DECL_DUMMIES
  36 #endif
  37
  38 #ifndef errno
  39 volatile int __errno;
  40 strong_alias (__errno, errno)
  41 #endif
  42
  43 extern void __libc_init __P ((int argc, char **argv, char **envp));
  44 extern int main __P ((int argc, char **argv, char **envp));
  45
  46
  47 /* Not a prototype because it gets called strangely.  */
  48 static void start1();
  49
  50 #ifndef HAVE__start
  51
  52 /* N.B.: It is important that this be the first function.
  53    This file is the first thing in the text section.  */
  54 void
  55 _start ()
  56 {
  57   start1 ();
  58 }
  59
  60 #ifndef NO_UNDERSCORES
  61 /* Make an alias called `start' (no leading underscore, so it can't
  62    conflict with C symbols) for `_start'.  This is the name vendor crt0.o's
  63    tend to use, and thus the name most linkers expect.  */
  64 asm (".set start, __start");
  65 #endif
  66
  67 #endif
  68
  69 /* ARGSUSED */
  70 static void
  71 start1 (ARG_DUMMIES argc, argp)
  72      DECL_DUMMIES
  73      int argc;
  74      char *argp;
  75 {
  76   char **argv = &argp;
  77
  78   /* The environment starts just after ARGV.  */
  79   __environ = &argv[argc + 1];
  80
  81   /* If the first thing after ARGV is the arguments
  82      themselves, there is no environment.  */
  83   if ((char *) __environ == *argv)
  84     /* The environment is empty.  Make __environ
  85        point at ARGV[ARGC], which is NULL.  */
  86     --__environ;
  87
  88   /* Do C library initializations.  */
  89   __libc_init (argc, argv, __environ);
  90
  91   /* Call the user program.  */
  92   exit (main (argc, argv, __environ));
  93 }