[bug#51878] [PATCH] installer: Rework installation device detection

[Mathieu Othacehe]

Hello Josselin,

> properly detect the device as it was comparing a disk block device path (eg
> `/dev/sda`) with a partition block device path (`/dev/sda2`).  Instead, this

When using an ISO installer image,

> -                (or (read-only? device)
> -                    (and install-device
> -                         (string=? file-name install-device)))))
> -            (devices))))

file-name and install-device both equal "/dev/sr0" for the cdrom device,
which means it will be correctly filtered out. Is it handled correctly
with your patch?

When using a raw disk image, we may indeed compare devices and
partitions currently.

> +
> +  (define the-intaller-root-partition-path
> +    (installer-root-partition-path))
> +
> +  ;; Read partition table of device and compare each path to the one
> +  ;; we're booting from to determine if it is the installation
> +  ;; device.
> +  (define (installation-device? device)
> +    (let ((disk (disk-new device)))
> +      (and disk
> +           (let loop ((partition #f))
> +             (let ((next-partition (disk-next-partition disk
> +                                                        #:partition
> +                                                        partition)))
> +               (and next-partition
> +                    (or (string=? the-installer-root-partition-path
> +                                  (partition-get-path
> +                                   next-partition))
> +                        (loop next-partition))))))))

Filtering the "(devices)" list can cause extra iterations compared to
your implementation, but is easier to read I think.

Thanks,

Mathieu