re PR libfortran/30162 (Document when sequential I/O with named pipes works)

re PR libfortran/30162 (Document when sequential I/O with named pipes works)

2007-01-05  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

	PR libgfortran/30162
	* io/unix.c (fd_flush): Don't seek if file is not seekable, defined as
	s->file_length == -1.
	(fd_alloc_w_at): Do not adjust file_length if file is not seekable.
	(fd_seek): If not seekable, just return success.
	(fd_truncate): If not seekable, no need to truncate.  Return failure if
	seek fails and the stream is not a pipe.
	(fd_to_stream): Make test for non-seekable file more robust.

From-SVN: r120512