[vte] [ring] Only write_contents() the part of history that fits in the num rows

[Behdad Esfahbod <behdad src gnome org>]

commit 38b6a46d413247d7acda50f7729048c635ffe23b
Author: Behdad Esfahbod <behdad behdad org>
Date:   Wed Jan 13 19:33:34 2010 -0500

    [ring] Only write_contents() the part of history that fits in the num rows

 src/ring.c           |   12 ++++++++++--
 src/vtestream-base.h |   12 +++++++++---
 src/vtestream-file.h |   19 +++++++++++++++----
 src/vtestream.h      |    4 +++-
 4 files changed, 37 insertions(+), 10 deletions(-)
---
diff --git a/src/ring.c b/src/ring.c
index e5a7e23..34855b1 100644
--- a/src/ring.c
+++ b/src/ring.c
@@ -609,8 +609,16 @@ _vte_ring_write_contents (VteRing *ring,
 
 	_vte_debug_print(VTE_DEBUG_RING, "Writing contents to GOutputStream.\n");
 
-	if (!_vte_stream_write_contents (ring->text_stream, stream, cancellable, error))
-		return FALSE;
+	if (ring->start < ring->writable) {
+		VteRowRecord record;
+		/* XXX what to do in case of error? */
+		if (_vte_ring_read_row_record (ring, &record, ring->start)) {
+			if (!_vte_stream_write_contents (ring->text_stream, stream,
+							 record.text_offset,
+							 cancellable, error))
+				return FALSE;
+		}
+	}
 
 	for (i = ring->writable; i < ring->end; i++) {
 		if (!_vte_ring_write_row (ring, stream,
diff --git a/src/vtestream-base.h b/src/vtestream-base.h
index 74b7301..913f9c9 100644
--- a/src/vtestream-base.h
+++ b/src/vtestream-base.h
@@ -38,7 +38,9 @@ typedef struct _VteStreamClass {
 	void (*truncate) (VteStream *stream, gsize offset);
 	void (*new_page) (VteStream *stream);
 	gsize (*head) (VteStream *stream);
-	gboolean (*write_contents) (VteStream *stream, GOutputStream *output, GCancellable *cancellable, GError **error);
+	gboolean (*write_contents) (VteStream *stream, GOutputStream *output,
+				    gsize start_offset,
+				    GCancellable *cancellable, GError **error);
 } VteStreamClass;
 
 static GType _vte_stream_get_type (void);
@@ -94,7 +96,11 @@ _vte_stream_head (VteStream *stream)
 }
 
 gboolean
-_vte_stream_write_contents (VteStream *stream, GOutputStream *output, GCancellable *cancellable, GError **error)
+_vte_stream_write_contents (VteStream *stream, GOutputStream *output,
+			    gsize start_offset,
+			    GCancellable *cancellable, GError **error)
 {
-	return VTE_STREAM_GET_CLASS (stream)->write_contents (stream, output, cancellable, error);
+	return VTE_STREAM_GET_CLASS (stream)->write_contents (stream, output,
+							      start_offset,
+							      cancellable, error);
 }
diff --git a/src/vtestream-file.h b/src/vtestream-file.h
index 707877b..bc92d6f 100644
--- a/src/vtestream-file.h
+++ b/src/vtestream-file.h
@@ -93,7 +93,6 @@ _xwrite_contents (gint fd, GOutputStream *output, GCancellable *cancellable, GEr
 	if (G_UNLIKELY (!fd))
 		return TRUE;
 
-	lseek (fd, 0, SEEK_SET);
 	input = g_unix_input_stream_new (fd, FALSE);
 	ret = -1 != g_output_stream_splice (output, input, G_OUTPUT_STREAM_SPLICE_NONE, cancellable, error);
 	g_object_unref (input);
@@ -260,12 +259,24 @@ _vte_file_stream_head (VteStream *astream)
 }
 
 static gboolean
-_vte_file_stream_write_contents (VteStream *astream, GOutputStream *output, GCancellable *cancellable, GError **error)
+_vte_file_stream_write_contents (VteStream *astream, GOutputStream *output,
+				 gsize offset,
+				 GCancellable *cancellable, GError **error)
 {
 	VteFileStream *stream = (VteFileStream *) astream;
 
-	return _xwrite_contents (stream->fd[1], output, cancellable, error) &&
-	       _xwrite_contents (stream->fd[0], output, cancellable, error);
+	if (G_UNLIKELY (offset < stream->offset[1]))
+		return FALSE;
+
+	if (offset < stream->offset[0]) {
+		lseek (stream->fd[1], offset - stream->offset[1], SEEK_SET);
+		if (!_xwrite_contents (stream->fd[1], output, cancellable, error))
+			return FALSE;
+		offset = stream->offset[0];
+	}
+
+	lseek (stream->fd[0], offset - stream->offset[0], SEEK_SET);
+	return _xwrite_contents (stream->fd[0], output, cancellable, error);
 }
 
 static void
diff --git a/src/vtestream.h b/src/vtestream.h
index f21e8b0..27a2829 100644
--- a/src/vtestream.h
+++ b/src/vtestream.h
@@ -34,7 +34,9 @@ gboolean _vte_stream_read (VteStream *stream, gsize offset, char *data, gsize le
 void _vte_stream_truncate (VteStream *stream, gsize offset);
 void _vte_stream_new_page (VteStream *stream);
 gsize _vte_stream_head (VteStream *stream);
-gboolean _vte_stream_write_contents (VteStream *stream, GOutputStream *output, GCancellable *cancellable, GError **error);
+gboolean _vte_stream_write_contents (VteStream *stream, GOutputStream *output,
+				     gsize start_offset,
+				     GCancellable *cancellable, GError **error);
 
 
 /* Various streams */