From 1f0f1dd320d4b37ce1c6bce49e64b7f4c797b45a Mon Sep 17 00:00:00 2001
From: FRIGN <dev@frign.de>
Date: Sat, 21 Mar 2015 14:04:49 +0100
Subject: [PATCH] Show usage() when filtermode is given for tar-creation

We only allow decompression for extraction. Thus, it may be confusing
for the user and break scripts silently when the j- or z-flag are given
even though this is not supported.
---
 tar.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tar.c b/tar.c
index 9606515..31cc399 100644
--- a/tar.c
+++ b/tar.c
@@ -52,7 +52,7 @@ static ino_t tarinode;
 static dev_t tardev;
 
 static int  mflag;
-static char filtermode;
+static char filtermode = '\0';
 
 static FILE *
 decomp(FILE *fp)
@@ -348,6 +348,8 @@ main(int argc, char *argv[])
 
 	if (!mode || argc != (mode == 'c'))
 		usage();
+	if (mode == 'c' && filtermode)
+		usage();
 
 	switch (mode) {
 	case 'c':