/*
       *  linux/fs/binfmt_script.c
       *
       *  Copyright (C) 1996  Martin von Löwis
       *  original #!-checking implemented by tytso.
       */
      
      #include <linux/module.h>
      #include <linux/string.h>
      #include <linux/stat.h>
      #include <linux/malloc.h>
      #include <linux/binfmts.h>
      #include <linux/init.h>
      #include <linux/file.h>
      #include <linux/smp_lock.h>
      
  17  static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
      {
      	char *cp, *i_name, *i_arg;
      	struct file *file;
      	char interp[BINPRM_BUF_SIZE];
      	int retval;
      
  24  	if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang)) 
  25  		return -ENOEXEC;
      	/*
      	 * This section does the #! interpretation.
      	 * Sorta complicated, but hopefully it will work.  -TYT
      	 */
      
      	bprm->sh_bang++;
      	allow_write_access(bprm->file);
      	fput(bprm->file);
      	bprm->file = NULL;
      
      	bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
  37  	if ((cp = strchr(bprm->buf, '\n')) == NULL)
      		cp = bprm->buf+BINPRM_BUF_SIZE-1;
      	*cp = '\0';
  40  	while (cp > bprm->buf) {
      		cp--;
  42  		if ((*cp == ' ') || (*cp == '\t'))
      			*cp = '\0';
  44  		else
  45  			break;
      	}
  47  	for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  48  	if (*cp == '\0') 
  49  		return -ENOEXEC; /* No interpreter name found */
      	i_name = cp;
      	i_arg = 0;
  52  	for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
      		/* nothing */ ;
  54  	while ((*cp == ' ') || (*cp == '\t'))
      		*cp++ = '\0';
  56  	if (*cp)
      		i_arg = cp;
      	strcpy (interp, i_name);
      	/*
      	 * OK, we've parsed out the interpreter name and
      	 * (optional) argument.
      	 * Splice in (1) the interpreter's name for argv[0]
      	 *           (2) (optional) argument to interpreter
      	 *           (3) filename of shell script (replace argv[0])
      	 *
      	 * This is done in reverse order, because of how the
      	 * user environment and arguments are stored.
      	 */
      	remove_arg_zero(bprm);
      	retval = copy_strings_kernel(1, &bprm->filename, bprm);
  71  	if (retval < 0) return retval; 
      	bprm->argc++;
  73  	if (i_arg) {
      		retval = copy_strings_kernel(1, &i_arg, bprm);
  75  		if (retval < 0) return retval; 
      		bprm->argc++;
      	}
      	retval = copy_strings_kernel(1, &i_name, bprm);
  79  	if (retval) return retval; 
      	bprm->argc++;
      	/*
      	 * OK, now restart the process with the interpreter's dentry.
      	 */
      	file = open_exec(interp);
  85  	if (IS_ERR(file))
  86  		return PTR_ERR(file);
      
      	bprm->file = file;
      	retval = prepare_binprm(bprm);
  90  	if (retval < 0)
  91  		return retval;
  92  	return search_binary_handler(bprm,regs);
      }
      
      struct linux_binfmt script_format = {
      	NULL, THIS_MODULE, load_script, NULL, NULL, 0
      };
      
  99  static int __init init_script_binfmt(void)
      {
 101  	return register_binfmt(&script_format);
      }
      
 104  static void __exit exit_script_binfmt(void)
      {
      	unregister_binfmt(&script_format);
      }
      
      module_init(init_script_binfmt)
      module_exit(exit_script_binfmt)