streams: seek-stream must fail on extracted string out stream.

* stream.c (string_out_seek): Do the extracted error check so
that we fail if the data has already been removed form the
stream. There is a test case already for this, which is
failing.

1 files changed, 3 insertions, 0 deletions

diff --git a/stream.c b/stream.c
index 03269dd6..0fbca432 100644
--- a/stream.c
+++ b/stream.c
@@ -2612,6 +2612,9 @@ static val string_out_seek(val stream, val off, enum strm_whence whence)
   val self = lit("seek-stream");
   val pos, len = nil;
 
+  if (so->buf == 0)
+    string_out_extracted_error(stream);
+
   while (so->head != so->tail)
     string_out_byte_flush(so, stream);