Re: [libvirt] [PATCH] Implement vol delete for disk pools

On Mon, Aug 11, 2008 at 03:58:41PM -0400, Cole Robinson wrote: > The patch below implements virStorageVolDelete for volumes > on a disk pool. > > The only interesting thing here is that parted wants a > partition number to delete, so we need to peel off the > end of the volume's target path which will be of the form > '/dev/sda1' or similar (I assume. If not, it's still > better than having nothing implemented). > > Thanks, > Cole > > { > - /* delete a partition */ > - virStorageReportError(conn, VIR_ERR_NO_SUPPORT, > - _("Disk pools are not yet supported")); > - return -1; > + char *part_num = NULL; > + int i; > + > + /* Strip target path (ex. '/dev/sda1') of its partition number */ > + for (i = (strlen(vol->target.path)-1); i >= 0; --i) { > + if (!c_isdigit(vol->target.path[i])) > + break; > + part_num = &(vol->target.path[i]); > + } > + > + if (!part_num) { > + virStorageReportError(conn, VIR_ERR_INTERNAL_ERROR, > + _("cannot parse partition number from target " > + "path '%s'"), vol->target.path); > + return -1; > + } > This isn't correct because the target path is not guarenteed to point to the master device name /dev/sda1. The user could have configured it to use a stable path such as /dev/disk/by-uuid/4cb23887-0d02-4e4c-bc95-7599c85afc1a

So, you need to first call 'readlink' on the vol->target.path, ignoring EINVAL which you'll get if it wasn't a symlink. Once you've done that you'll need to validate that it is sane by checking that vol->source.devices[0] is a prefix of the resolved pathname. Finally, you can extract the partition number. So something along the lines of char devname[PATH_MAX]; if (readlink(vol->target.path, devname, sizeof(devname)) < 0 && errno != EINVAL) virStorageReportError(...) if (!STRPREFIX(devname, vol->source.devices[0].path)) virStorageReportError(....) part_num = devname + strlen(vol->source.devices[0].path)