When writing batches of characters to the screen, we need to clear

padding or later UTF-8 characters could be displayed incorrectly. GitHub
issue 1090.

1 files changed, 24 insertions, 1 deletions

diff --git a/usr.bin/tmux/screen-write.c b/usr.bin/tmux/screen-write.c
index 4adcdcb317d..93489c9b9e3 100644
--- a/usr.bin/tmux/screen-write.c
+++ b/usr.bin/tmux/screen-write.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.130 2017/08/09 11:43:45 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.131 2017/10/05 08:12:24 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1243,6 +1243,7 @@ screen_write_collect_end(struct screen_write_ctx *ctx)
 	struct screen				*s = ctx->s;
 	struct screen_write_collect_item	*ci = ctx->item;
 	struct grid_cell			 gc;
+	u_int					 xx;
 
 	if (ci->used == 0)
 		return;
@@ -1255,9 +1256,27 @@ screen_write_collect_end(struct screen_write_ctx *ctx)
 	log_debug("%s: %u %s (at %u,%u)", __func__, ci->used, ci->data, s->cx,
 	    s->cy);
 
+	if (s->cx != 0) {
+		for (xx = s->cx; xx > 0; xx--) {
+			grid_view_get_cell(s->grid, xx, s->cy, &gc);
+			if (~gc.flags & GRID_FLAG_PADDING)
+				break;
+			grid_view_set_cell(s->grid, xx, s->cy, &grid_default_cell);
+		}
+		if (gc.data.width > 1)
+			grid_view_set_cell(s->grid, xx, s->cy, &grid_default_cell);
+	}
+
 	memcpy(&gc, &ci->gc, sizeof gc);
 	grid_view_set_cells(s->grid, s->cx, s->cy, &gc, ci->data, ci->used);
 	s->cx += ci->used;
+
+	for (xx = s->cx; xx < screen_size_x(s); xx++) {
+		grid_view_get_cell(s->grid, xx, s->cy, &gc);
+		if (~gc.flags & GRID_FLAG_PADDING)
+			break;
+		grid_view_set_cell(s->grid, xx, s->cy, &grid_default_cell);
+	}
 }
 
 /* Write cell data, collecting if necessary. */
@@ -1388,6 +1407,7 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 	 * already ensured there is enough room.
 	 */
 	for (xx = s->cx + 1; xx < s->cx + width; xx++) {
+		log_debug("%s: new padding at %u,%u", __func__, xx, s->cy);
 		grid_view_set_cell(gd, xx, s->cy, &screen_write_pad_cell);
 		skip = 0;
 	}
@@ -1537,10 +1557,12 @@ screen_write_overwrite(struct screen_write_ctx *ctx, struct grid_cell *gc,
 			grid_view_get_cell(gd, xx, s->cy, &tmp_gc);
 			if (~tmp_gc.flags & GRID_FLAG_PADDING)
 				break;
+			log_debug("%s: padding at %u,%u", __func__, xx, s->cy);
 			grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
 		}
 
 		/* Overwrite the character at the start of this padding. */
+		log_debug("%s: character at %u,%u", __func__, xx, s->cy);
 		grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
 		done = 1;
 	}
@@ -1557,6 +1579,7 @@ screen_write_overwrite(struct screen_write_ctx *ctx, struct grid_cell *gc,
 			grid_view_get_cell(gd, xx, s->cy, &tmp_gc);
 			if (~tmp_gc.flags & GRID_FLAG_PADDING)
 				break;
+			log_debug("%s: overwrite at %u,%u", __func__, xx, s->cy);
 			grid_view_set_cell(gd, xx, s->cy, &grid_default_cell);
 			done = 1;
 		}