evbuffer: fix last_with_datap after prepend with empty chain

last_with_datap should be adjusted only if it buf->first *was* not
empty, otherwise last_with_datap should point to the prepended chain.

1 files changed, 1 insertions, 1 deletions

diff --git a/buffer.c b/buffer.c
index 11b1bdae..6ad8fd24 100644
--- a/buffer.c
+++ b/buffer.c
@@ -1905,7 +1905,7 @@ evbuffer_prepend(struct evbuffer *buf, const void *data, size_t datlen)
 	if ((tmp = evbuffer_chain_new(datlen)) == NULL)
 		goto done;
 	buf->first = tmp;
-	if (buf->last_with_datap == &buf->first)
+	if (buf->last_with_datap == &buf->first && chain->off)
 		buf->last_with_datap = &tmp->next;
 
 	tmp->next = chain;