diff -ruN vsftpd-3.0.3.orig/sysstr.c vsftpd-3.0.3/sysstr.c
--- vsftpd-3.0.3.orig/sysstr.c	2020-11-17 09:47:03.872923383 +0100
+++ vsftpd-3.0.3/sysstr.c	2020-11-17 09:48:41.219754145 +0100
@@ -74,19 +74,11 @@
 int
 str_open(const struct mystr* p_str, const enum EVSFSysStrOpenMode mode)
 {
-  enum EVSFSysUtilOpenMode open_mode = kVSFSysStrOpenUnknown;
-  switch (mode)
-  {
-    case kVSFSysStrOpenReadOnly:
-      open_mode = kVSFSysUtilOpenReadOnly;
-      break;
-    case kVSFSysStrOpenUnknown:
-      /* Fall through */
-    default:
-      bug("unknown mode value in str_open");
-      break;
-  }
-  return vsf_sysutil_open_file(str_getbuf(p_str), open_mode);
+  if (mode == kVSFSysStrOpenReadOnly)
+    return vsf_sysutil_open_file(str_getbuf(p_str), kVSFSysUtilOpenReadOnly);
+
+  bug("unknown mode value in str_open");
+  return -1;
 }
 
 int