[PATCH] {,un}applychange: do not call zle_setline(NULL) if quietgethist() fails

[Kamil Dudka <kdudka@xxxxxxxxxx>]

There is a bug report in Red Hat Bugzilla about zsh crashing on NULL
pointer dereference: https://bugzilla.redhat.com/1722703

I was not able to reproduce the crash myself but the attached patch
should prevent zsh from crashing in this situation.
---
 Src/Zle/zle_utils.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Src/Zle/zle_utils.c b/Src/Zle/zle_utils.c
index 0277d4917..8081d3adc 100644
--- a/Src/Zle/zle_utils.c
+++ b/Src/Zle/zle_utils.c
@@ -1607,7 +1607,9 @@ static int
 unapplychange(struct change *ch)
 {
     if(ch->hist != histline) {
-	zle_setline(quietgethist(ch->hist));
+	Histent he = quietgethist(ch->hist);
+	if(he)
+	    zle_setline(he);
 	zlecs = ch->new_cs;
 	return 0;
     }
@@ -1647,7 +1649,9 @@ static int
 applychange(struct change *ch)
 {
     if(ch->hist != histline) {
-	zle_setline(quietgethist(ch->hist));
+	Histent he = quietgethist(ch->hist);
+	if(he)
+	    zle_setline(he);
 	zlecs = ch->old_cs;
 	return 0;
     }
-- 
2.20.1