Re: [Libguestfs] [PATCH] Don't use libvirt for volume information when converting with libvirtxml

On Wed, Jan 26, 2011 at 02:34:49PM +0000, Matthew Booth wrote: > Unless you're lucky, the target volumes won't be in a storage pool, so libvirt > will return an error. For libvirtxml we know that the storage is local, so we > can inspect it directly. We use qemu-img to determine format and file size. [...] > + # Use the output of qemu-img to inspect the path > + open(my $qemuimg, '-|', 'env', 'LANG=C', 'qemu-img', 'info', $path) > + or die("Unable to execute qemu-img: $!"); You need to make sure qemu-img is an explicit Requires in the spec file, ie: Requires: /usr/bin/qemu-img and it should be mentioned in the README file too for other distros. Also other distros name this differently, eg: 'kvm-qemu-img' and maybe other variations. > + # For $usage, $is_sparse and $is_block, we need to know if it's a block > + # device > + # N.B. qemu-img's 'disk size' output isn't useful here > + my ($usage, $is_sparse, $is_block); > + if (-b $path) { > + $is_block = 1; > + $usage = $size; > + $is_sparse = 0; > + } else { > + $is_block = 0; > + my $st = stat($path); > + $usage = $st->blocks * 512; > + $is_sparse = $usage < $size ? 1 : 0; > + } > + > + die("size ($size) < usage ($usage)") if $size < $usage; Agreed that qemu-img gets it wrong: # qemu-img info /dev/vg_pin/CentOS5x64 image: /dev/vg_pin/CentOS5x64 file format: raw virtual size: 10G (10737418240 bytes) disk size: 0 *but* I'm not sure your code is correct. I don't know if $st->blocks is always valid, and you can't assume 512-sized blocks.

I suggest calling 'blockdev --getsize64', with the caveats above about dependencies and README file.