sysdeps/unix/start.c

   1 /* Copyright (C) 1991, 93, 1995-1998, 2000 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    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 /* __errno must be initialized since otherwise one cannot create an
  40    alias (at least on some platforms).  */
  41 volatile int __errno = 0;
  42 strong_alias (__errno, errno)
  43 #endif
  44
  45 extern void __libc_init (int argc, char **argv, char **envp);
  46 extern int main (int argc, char **argv, char **envp);
  47
  48
  49 /* Not a prototype because it gets called strangely.  */
  50 static void start1();
  51
  52 #ifndef HAVE__start
  53
  54 /* N.B.: It is important that this be the first function.
  55    This file is the first thing in the text section.  */
  56 void
  57 _start ()
  58 {
  59   start1 ();
  60 }
  61
  62 #ifndef NO_UNDERSCORES
  63 /* Make an alias called `start' (no leading underscore, so it can't
  64    conflict with C symbols) for `_start'.  This is the name vendor crt0.o's
  65    tend to use, and thus the name most linkers expect.  */
  66 asm (".set start, __start");
  67 #endif
  68
  69 #endif
  70
  71 /* ARGSUSED */
  72 static void
  73 start1 (ARG_DUMMIES argc, argp)
  74      DECL_DUMMIES
  75      int argc;
  76      char *argp;
  77 {
  78   char **argv = &argp;
  79
  80   /* The environment starts just after ARGV.  */
  81   __environ = &argv[argc + 1];
  82
  83   /* If the first thing after ARGV is the arguments
  84      themselves, there is no environment.  */
  85   if ((char *) __environ == *argv)
  86     /* The environment is empty.  Make __environ
  87        point at ARGV[ARGC], which is NULL.  */
  88     --__environ;
  89
  90   /* Do C library initializations.  */
  91   __libc_init (argc, argv, __environ);
  92
  93   /* Call the user program.  */
  94   exit (main (argc, argv, __environ));
  95 }