[Libguestfs] [PATCH] Fix device name mapping for libata guests

[Daniel P. Berrange]

On Tue, Oct 12, 2010 at 02:05:25PM +0100, Matthew Booth wrote:
> remap_block_devices was modifying the global device list while remapping device
> names for libata guests (which includes RHEL 6). This caused a failure later
> when the renamed devices were not present in the original XML.
> 
> Fixes RHBZ#641869
> ---
>  lib/Sys/VirtV2V/GuestOS/RedHat.pm |   14 +++++++++++++-
>  1 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/lib/Sys/VirtV2V/GuestOS/RedHat.pm b/lib/Sys/VirtV2V/GuestOS/RedHat.pm
> index a322a5d..cc95fd8 100644
> --- a/lib/Sys/VirtV2V/GuestOS/RedHat.pm
> +++ b/lib/Sys/VirtV2V/GuestOS/RedHat.pm
> @@ -1567,7 +1567,19 @@ sub remap_block_devices
>                  $letter++;
>              }
>  
> -            map { $_ = $map{$_} } @$devices;
> +            # N.B. Don't use map() here because we mustn't modify the original
> +            # devices list

The problem isn't that you used map(), it is that your map code block
has side effects. You should be able to avoid the side effect thus:

      my @newdevices = map { $map{$_} } @$devices;

> +            my @newdevices;
> +            foreach my $device (@$devices) {
> +                my $map = $map{$device};
> +
> +                unless (defined($map)) {
> +                    warn ("No mapping for device $device");
> +                    next;
> +                }
> +                push(@newdevices, $map);
> +            }
> +            $devices = \@newdevices;
>          }


Regards,
Daniel
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