Red Hat Bugzilla – Bug 679737
libguestfs: improve error message when zerofree is not available in the appliance
Last modified: 2012-06-20 02:59:28 EDT
Description of problem: zerofree is unavailable in RHEL 6. Version-Release number of selected component (if applicable): libguestfs-1.7.17-14.el6 How reproducible: Always Steps to Reproduce: $ guestfish ><fs> alloc test.img 100M ><fs> run ><fs> mkfs ext2 /dev/sda ><fs> zerofree /dev/sda libguestfs: error: zerofree: /dev/vda: zerofree: No such file or directory
In some sense this is correct :-) Try doing the following command in guestfish (requires the "run" command to have been done first): ><fs> supported At the end of the list you should see "zerofree no" indicating that the zerofree command isn't available in the daemon. Also: http://libguestfs.org/guestfs.3.html#availability However it may be that we need to either: (1) Add zerofree as a new package to RHEL 6 (probably not advisable, it's a rather experimental package which can destroy filesystems if it is not used correctly) (2) Improve the error message. Anyway, this is a 6.2 thing I think, so I have reset the flags to 6.2 ...
Well. If zerofree is too dangerous to RHEL 6, why is it still in libguestfs since it could be impossibly available? Some groups (like ntfs3g) are optional by providing a separate support package. But we'll never get zerofree. Shouldn't it be removed from libguestfs like in 6.0?
The problem is that if we remove the underlying API (ie. guestfs_zerofree) then some programs wouldn't compile. If programmers are following the documentation, then they should be calling guestfs_available first before using guestfs_zerofree, and they should also check the return value from guestfs_zerofree for errors. We could remove it leave it in the API but remove it from guestfish, but that just makes guestfish irregular -- we document that guestfish has an equivalent for every libguestfs API call. Also it is conceivable that a RHEL 6 user could prepare a package containing zerofree + the relevant supermin appliance changes which would transparently add zerofree support back into libguestfs. This is roughly what libguestfs-winsupport does for ntfs-3g. I don't think there is a good answer to this, although improving the error message would be a good idea.
6.3 material, unless a customer complains about this. zerofree is dangerous. To add it to RHEL we'd need to have the code fully and properly checked by Ric Wheeler and friends.
Reproducer: $ guestfish -N fs zerofree /dev/sda1 libguestfs: error: zerofree: /dev/vda1: zerofree: No such file or directory Note this creates/overwrites a file in the current directory called 'test1.img', so: $ rm test1.img
Patch posted: https://www.redhat.com/archives/libguestfs/2012-February/msg00000.html
Updated patch posted: https://www.redhat.com/archives/libguestfs/2012-February/msg00002.html
Committed upstream: https://github.com/libguestfs/libguestfs/commit/330fbea5b2d6bd7db84f7ea7afe87cf1bcd438e0
The patch is incomplete and causes the daemon to segfault in some circumstances. Patch posted to fix that: https://www.redhat.com/archives/libguestfs/2012-February/msg00057.html
Fix included in libguestfs 1.17.7: https://github.com/libguestfs/libguestfs/commit/ba443ae0486ae30ea597c4e126de63371f8fa7a8 and this will be backported to 1.16 branch and RHEL 6.3.
The fix is included in upstream stable branch version 1.16.5, and in RHEL 6.3 build (same version).
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: No Documentation needed
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2012-0774.html