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root/cebix/BasiliskII/src/Unix/vhd_unix.h
Revision: 1.1
Committed: 2010-10-19T03:21:52Z (13 years, 6 months ago) by asvitkine
Content type: text/plain
Branch: MAIN
CVS Tags: HEAD
Log Message:
[Geoffrey Brown]
For my work on digital preservation it's important to have "golden"
disk images that are not corrupted by user action.  In order to enable
this, I've added support for VHD virtual disks (especially snapshots !)
to the Linux and OS X versions of BasiliskII and SheepShaver.

The support uses the open source libvhd library which is part of xen,
available here:
  http://www.xen.org/products/xen_source.html

The piece that's needed is libvhd which is in tools/blktap2 and it can
be separately compiled.
The vhd-util enables creation of vhd disks and snapshots.

Compiling libvhd for OS X is non-trivial and required  1) a new config
and 2) a number of small changes to the include files and c files.
Compiling for linux is a snap.

I use this as follows.

1) create my "golden image"  gold.dsk in the usual way
2) create a snapshot:  vhd-util snapshot -n gold.vhd -p gold.dsk -m
3) use the snapshot in my prefs file

In my work the golden images are in an AFS system which means the golden
images can reside at "universal" addresses.   The snapshots are initially
tiny, so a complete virtual machine configuration -- prefs + snapshot is
quick to download for the end user.

The snapshots are copy on write which has the pleasant side effect of
letting the end user keep any changes.

File Contents

# Content
1 /*
2 * vhd_unix.h -- support for disk images in vhd format
3 *
4 * (C) 2010 Geoffrey Brown
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #ifndef VHD_H
22 #define VHD_H
23
24 void *vhd_unix_open(const char *name, int *size, bool read_only);
25 int vhd_unix_read(void *arg, void *buffer, loff_t offset, size_t length);
26 int vhd_unix_write(void *arg, void *buffer, loff_t offset, size_t length);
27 void vhd_unix_close(void *arg);
28
29 #endif