Flush pending output before entering or exiting alternate screen rather

than leaking it, oss-fuzz issue 29959.

1 files changed, 4 insertions, 0 deletions

diff --git a/screen-write.c b/screen-write.c
index f374630c..4811b0a1 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -1970,6 +1970,8 @@ screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	if (wp != NULL && !options_get_number(wp->options, "alternate-screen"))
 		return;
+
+	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_on(ctx->s, gc, cursor);
 
 	screen_write_initctx(ctx, &ttyctx, 1);
@@ -1986,6 +1988,8 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	if (wp != NULL && !options_get_number(wp->options, "alternate-screen"))
 		return;
+
+	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_off(ctx->s, gc, cursor);
 
 	screen_write_initctx(ctx, &ttyctx, 1);