Hi Sam,
Please try the attached patch.
Regards,
Sergey
>From 1847ec67cec36a17354115374954fea211d1f0da Mon Sep 17 00:00:00 2001
From: Sergey Poznyakoff <g...@gnu.org.ua>
Date: Thu, 19 Feb 2015 17:00:58 +0200
Subject: [PATCH] Improve compression format recognition
Some comressed archives can pass the checksum test, which makes tar
treat them as uncompressed archives.
* src/buffer.c (check_compressed_archive): Test the checksum only
if the block we read looks like a valid tar header (i.e. has
a magic string).
---
src/buffer.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/buffer.c b/src/buffer.c
index a7d8971..1a96595 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -391,7 +391,10 @@ check_compressed_archive (bool *pshort)
/* Restore global values */
read_full_records = sfr;
- if (tar_checksum (record_start, true) == HEADER_SUCCESS)
+ if ((strcmp (record_start->header.magic, TMAGIC) == 0 ||
+ strcmp (record_start->buffer + offsetof (struct posix_header, magic),
+ OLDGNU_MAGIC) == 0) &&
+ tar_checksum (record_start, true) == HEADER_SUCCESS)
/* Probably a valid header */
return ct_tar;
--
1.7.12.1
