rexec.py 文件源码

def r_open(self, file, mode='r', buf=-1):
        """Method called when open() is called in the restricted environment.

        The arguments are identical to those of the open() function, and a
        file object (or a class instance compatible with file objects)
        should be returned.  RExec's default behaviour is allow opening
        any file for reading, but forbidding any attempt to write a file.

        This method is implicitly called by code executing in the
        restricted environment.  Overriding this method in a subclass is
        used to change the policies enforced by a restricted environment.

        """
        mode = str(mode)
        if mode not in ('r', 'rb'):
            raise IOError, "can't open files for writing in restricted mode"
        return open(file, mode, buf)

    # Restricted version of sys.exc_info()