From cb78bb0949a5be6eab74c32f690bfca306b24001 Mon Sep 17 00:00:00 2001
From: Rob Davies <rmd+git@sanger.ac.uk>
Date: Mon, 12 Aug 2024 09:38:47 +0100
Subject: [PATCH] Check underlying hopen() worked for preload: URLs

Otherwise, we might try to hread() a NULL pointer.

Credit to OSS_Fuzz
Fixes oss-fuzz id 71069
---
 hfile.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hfile.c b/hfile.c
index 1241dcccb..552b71774 100644
--- a/hfile.c
+++ b/hfile.c
@@ -703,7 +703,7 @@ static int is_preload_url_remote(const char *url){
 
 static hFILE *hopen_preload(const char *url, const char *mode){
     hFILE* fp = hopen(url + 8, mode);
-    return hpreload(fp);
+    return fp ? hpreload(fp) : NULL;
 }
 
 hFILE *hdopen(int fd, const char *mode)