Description: Detect old-style GNU headers correctly

Author: Steinar H. Gunderson <sesse@debian.org>

--- libtar-1.2.20.orig/lib/decode.c

+++ libtar-1.2.20/lib/decode.c

@@ -69,7 +69,14 @@ th_get_pathname(TAR *t)

 			return NULL;

 	}

-	if (t->th_buf.prefix[0] == '\0')

+	/*

+	 * Old GNU headers (also used by newer GNU tar when doing incremental

+	 * dumps) use the POSIX prefix field for many other things, such as

+	 * mtime and ctime. New-style GNU headers don't, but also don't use the

+	 * POSIX prefix field. Thus, only honor the prefix field if the archive

+	 * is actually a POSIX archive. This is the same logic as GNU tar uses.

+	 */

+	if (strncmp(t->th_buf.magic, TMAGIC, TMAGLEN - 1) != 0 || t->th_buf.prefix[0] == '\0')

 	{

 		sprintf(t->th_pathname, "%.100s", t->th_buf.name);

 	}