RFC: #mtree signature

I'm experimenting with having bsdtar able to
read mtree files and convert them into
tar archives.  This works quite well, although
there is one stumbling block:  libarchive
likes to auto-detect formats and the current mtree
format lacks any mandatory leading signature.

Any concerns or thoughts about the following
patch, which simply adds "#mtree" as the first
line of every mtree file?

I would also, of course, like to:
   * add this signature to the FreeBSD /etc/mtree/
files as a first step towards getting this convention
to be more widely adopted and used,
   * update /etc/magic to reflect this convention,
   * get this added to NetBSD's "mtree" utility.

Tim Kientzle


Index: create.c
===================================================================
RCS file: /usr/cvs/FreeBSD-CVS/src/usr.sbin/mtree/create.c,v
retrieving revision 1.37
diff -u -r1.37 create.c
--- create.c    29 Mar 2005 11:44:17 -0000      1.37
+++ create.c    18 Aug 2007 23:52:06 -0000
_at__at_ -87,6 +87,7 _at__at_
         char dot[] = ".";
         int indent = 0;

+       (void)printf("#mtree\n");
         if (!nflag) {
                 (void)time(&cl);
                 (void)gethostname(host, sizeof(host));