Create external disk-probe crate for probing information on disks

[mmstick]

The end goal is to remove all disk probing logic from distinst, so that it can focus on installations. A crate for probing disk information can be created which will probe information quickly. Currently, distinst uses a mixture of parted (extremely slow at probing), accessing info from /sys/class/block, and shelling out to external commands (error-prone / slow).

Distinst should only use parted when it needs to partition disks. The disk-probing functionality in parted is extremely slow. So slow, in fact, that it can take up to entire minute to complete one probe on some systems. This makes the UI of the installer very unresponsive, as it needs to reload information from time to time.

The /proc/partitions file contains a list of available partitions, and their

• MAJOR / MINOR
• BLOCKS
• NAME

On Linux, libblkid can be used to get the following info from /dev/$NAME:

• FSTYPE
• UUID
• PARTTYPE
• PARTUUID
• PARTFLAGS
• LABEL
• PARTTABLE
• START
• OFFSET
• SECTOR_SIZE
• SECTOR_COUNT

We already have a proc-mounts crate which can be used to reference mount points.

Linux provides a /sys/class/block interface which gives access to:

• DMNAME (/dm/name)
• DMUUID (/dm/uuid)
• MODEL
• SERIAL
• VENDOR
• Slaves (/slaves)
• everything else

The end goal should be to gather all this information in a meaningful way, so that we can get an output similar to lsblk, which could be used as the basis for a disk management library (ecs-disk-manager). This crate should work closely with our disk-types crate, and then ultimately integrate itself within ecs-disk-manager to replace the udisks daemon.