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    In addition to the permissions in the GNU Lesser General Public
  10    License, the Free Software Foundation gives you unlimited
  11    permission to link the compiled version of this file with other
  12    programs, and to distribute those programs without any restriction
  13    coming from the use of this file. (The GNU Lesser General Public
  14    License restrictions do apply in other respects; for example, they
  15    cover modification of the file, and distribution when not linked
  16    into another program.)
  17
  18    Note that people who make modified versions of this file are not
  19    obligated to grant this special exception for their modified
  20    versions; it is their choice whether to do so. The GNU Lesser
  21    General Public License gives permission to release a modified
  22    version without this exception; this exception also makes it
  23    possible to release a modified version which carries forward this
  24    exception.
  25
  26    The GNU C Library is distributed in the hope that it will be useful,
  27    but WITHOUT ANY WARRANTY; without even the implied warranty of
  28    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29    Lesser General Public License for more details.
  30
  31    You should have received a copy of the GNU Lesser General Public
  32    License along with the GNU C Library; if not, write to the Free
  33    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  34    02111-1307 USA.  */
  35
  36 #include <errno.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39 #include <sysdep.h>             /* In case it wants to define anything.  */
  40
  41 /* The first piece of initialized data.  */
  42 int __data_start = 0;
  43 #ifdef HAVE_WEAK_SYMBOLS
  44 weak_alias (__data_start, data_start)
  45 #endif
  46
  47 #ifdef  DUMMIES
  48 #define ARG_DUMMIES     DUMMIES,
  49 #define DECL_DUMMIES    int DUMMIES;
  50 #else
  51 #define ARG_DUMMIES
  52 #define DECL_DUMMIES
  53 #endif
  54
  55 extern void __libc_init (int argc, char **argv, char **envp);
  56 extern int main (int argc, char **argv, char **envp);
  57
  58
  59 /* Not a prototype because it gets called strangely.  */
  60 static void start1();
  61
  62 #ifndef HAVE__start
  63
  64 /* N.B.: It is important that this be the first function.
  65    This file is the first thing in the text section.  */
  66 void
  67 _start ()
  68 {
  69   start1 ();
  70 }
  71
  72 #ifndef NO_UNDERSCORES
  73 /* Make an alias called `start' (no leading underscore, so it can't
  74    conflict with C symbols) for `_start'.  This is the name vendor crt0.o's
  75    tend to use, and thus the name most linkers expect.  */
  76 asm (".set start, __start");
  77 #endif
  78
  79 #endif
  80
  81 /* ARGSUSED */
  82 static void
  83 start1 (ARG_DUMMIES argc, argp)
  84      DECL_DUMMIES
  85      int argc;
  86      char *argp;
  87 {
  88   char **argv = &argp;
  89
  90   /* The environment starts just after ARGV.  */
  91   __environ = &argv[argc + 1];
  92
  93   /* If the first thing after ARGV is the arguments
  94      themselves, there is no environment.  */
  95   if ((char *) __environ == *argv)
  96     /* The environment is empty.  Make __environ
  97        point at ARGV[ARGC], which is NULL.  */
  98     --__environ;
  99
 100   /* Do C library initializations.  */
 101   __libc_init (argc, argv, __environ);
 102
 103   /* Call the user program.  */
 104   exit (main (argc, argv, __environ));
 105 }