From 9f5c311e4561a855a1b6882c6003134fadab7d3b Mon Sep 17 00:00:00 2001
From: Rene Kita <mail@rkta.de>
Date: Tue, 28 Dec 2021 20:58:13 +0100
Subject: [PATCH] Do not call fclose() on a NULL pointer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The if clause is true if cache is NULL. man 3 fclose says:

  The  behaviour  of  fclose() is undefined if the stream parameter is an
  illegal pointer, or is a descriptor already passed to a previous  invo‐
  cation of fclose().

Check if cache is NULL before calling fclose().
---
 buffer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/buffer.c b/buffer.c
index 083ecf6..f4a0377 100644
--- a/buffer.c
+++ b/buffer.c
@@ -707,7 +707,8 @@ readBufferCache(Buffer *buf)
 
     cache = fopen(buf->savecache, "r");
     if (cache == NULL || fread1(clnum, cache) || fread1(tlnum, cache)) {
-	fclose(cache);
+	if (cache != NULL)
+	    fclose(cache);
 	buf->savecache = NULL;
 	return -1;
     }