Re: [Libguestfs] [PATCH v3 1/2] NEW API: add a new api wipefs

On 02/09/2012 10:12 PM, Richard W.M. Jones wrote: > On Wed, Feb 08, 2012 at 01:32:47PM +0800, Wanlong Gao wrote: >> Add the new api wipefs to erase the filesystem signatures >> on a device but now erase any data. > > Having had a bit of time to think about this, I think this comment is > right: > >> -guestfs_zero should use wipefs. See wipefs(8). > > wipefs is generally better (than "zero") in that it knows about what's > on the disk (via blkid) and only overwrites the minimum necessary to > remove partition tables, RAID signatures etc. This is good. > > What's bad is that: (1) It probably doesn't work for formats that > blkid doesn't understand. (2) It doesn't preserve sparseness, > although arguably that doesn't matter because it's only overwriting > stuff that should be non-zero already. > > Cf: libblkid/src/probe.c:blkid_do_wipe > daemon/zero.c:do_zero > > On balance, I think that changing guestfs_zero to use wipefs is a > better way to approach this, but I'm open to opinions on this ... Yeah, I also considered about this, since wipefs can't erase the partition table, but guestfs_zero does, so, I'm afraid that if I use wipefs(8) to change the internal of guestfs_zero, the function also changed.