sysdeps/unix/start.c

   1 /* Copyright (C) 1991, 1993, 1995, 1996 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 modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation; either version 2, or (at your option)
   7 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
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with the GNU C Library; see the file COPYING.  If not, write to
  16 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 #include <errno.h>
  19 #include <stdlib.h>
  20 #include <unistd.h>
  21 #include <sysdep.h>             /* In case it wants to define anything.  */
  22
  23 /* The first piece of initialized data.  */
  24 int __data_start = 0;
  25 #ifdef HAVE_WEAK_SYMBOLS
  26 weak_alias (__data_start, data_start)
  27 #endif
  28
  29 #ifdef  DUMMIES
  30 #define ARG_DUMMIES     DUMMIES,
  31 #define DECL_DUMMIES    int DUMMIES;
  32 #else
  33 #define ARG_DUMMIES
  34 #define DECL_DUMMIES
  35 #endif
  36
  37 #ifndef errno
  38 volatile int __errno;
  39 string_alias (__errno, errno)
  40 #endif
  41
  42 extern void __libc_init __P ((int argc, char **argv, char **envp));
  43 extern int main __P ((int argc, char **argv, char **envp));
  44
  45
  46 /* Not a prototype because it gets called strangely.  */
  47 static void start1();
  48
  49 #ifndef HAVE__start
  50
  51 /* N.B.: It is important that this be the first function.
  52    This file is the first thing in the text section.  */
  53 void
  54 _start ()
  55 {
  56   start1 ();
  57 }
  58
  59 #ifndef NO_UNDERSCORES
  60 /* Make an alias called `start' (no leading underscore, so it can't
  61    conflict with C symbols) for `_start'.  This is the name vendor crt0.o's
  62    tend to use, and thus the name most linkers expect.  */
  63 asm (".set start, __start");
  64 #endif
  65
  66 #endif
  67
  68 /* ARGSUSED */
  69 static void
  70 start1 (ARG_DUMMIES argc, argp)
  71      DECL_DUMMIES
  72      int argc;
  73      char *argp;
  74 {
  75   char **argv = &argp;
  76
  77   /* The environment starts just after ARGV.  */
  78   __environ = &argv[argc + 1];
  79
  80   /* If the first thing after ARGV is the arguments
  81      themselves, there is no environment.  */
  82   if ((char *) __environ == *argv)
  83     /* The environment is empty.  Make __environ
  84        point at ARGV[ARGC], which is NULL.  */
  85     --__environ;
  86
  87   /* Do C library initializations.  */
  88   __libc_init (argc, argv, __environ);
  89
  90   /* Call the user program.  */
  91   exit (main (argc, argv, __environ));
  92 }