From 0b3ab3a934cf8c129986d5dd450bcc10f44db5b0 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Sun, 11 Sep 2022 14:26:53 +0100
Subject: [PATCH] fix null string in buffer print

Some libvips header fields can be NULL, for example filename, and we
need to avoid null pointer deref on print.

See https://github.com/libvips/libvips/issues/3043
---
 libvips/iofuncs/buf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libvips/iofuncs/buf.c b/libvips/iofuncs/buf.c
index 3061981a..19be0a91 100644
--- a/libvips/iofuncs/buf.c
+++ b/libvips/iofuncs/buf.c
@@ -262,6 +262,8 @@ vips_buf_appendns( VipsBuf *buf, const char *str, int sz )
 
 	if( buf->full )
 		return( FALSE );
+        if( !str )
+		return( TRUE );
 
 	/* Amount we want to copy.
 	 */
@@ -528,7 +530,7 @@ vips_buf_appendgv( VipsBuf *buf, GValue *value )
 		 * handled by boxed, see below.
 		 */
 		str = g_value_get_string( value );
-		result = vips_buf_appends( buf, str ); 
+                result = vips_buf_appends( buf, str ); 
 		handled = TRUE;
 }
 		break;