Re: [pve-devel] [PATCH qemu-server] cdrom handling: default to "none" if no physical drive is available

[Fiona Ebner <f.ebner@proxmox.com>]

Am 16.12.22 um 16:08 schrieb Stefan Sterz:
> when a vm is configured to use the physical cd rom drive but there is
> no such drive a cryptic "uninitialized value" error is thrown. this
> is due to the `$path` not being defined in `sub
> print_drive_commandline_full` in this case. warn that no cd rom drive
> is available and default back to using "none" as media instead.
> 
> note that the error was basically cosmetic as the vm would start just
> fine.
> 
> forum thread: https://forum.proxmox.com/threads/use-of-uninitialized-value-path-in-pattern-match-m-at-usr-share-perl5-pve-qemuserver-pm-line-1622.119592/

Note that the thread title is not needed for the link to work:
https://forum.proxmox.com/threads/119592/
Would avoid the long line in the commit message :)

> 
> Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>
> ---
>  PVE/QemuServer.pm | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index dd6ea3e..bc935df 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -1292,6 +1292,9 @@ sub get_cdrom_path {
>      return $cdrom_path = "/dev/cdrom" if -l "/dev/cdrom";
>      return $cdrom_path = "/dev/cdrom1" if -l "/dev/cdrom1";
>      return $cdrom_path = "/dev/cdrom2" if -l "/dev/cdrom2";
> +
> +    warn "there is no physical cdrom drive that can be used. defaulting back to 'none'.";

Missing newline at the end of the warning message. Perl will auto-attach
module and line number then, which gets ugly from a user perspective ;)

Nit: CD-ROM instead of cdrom

IMHO "defaulting back to 'none'." is a bit misleading. We don't actually
do that in the code, just also return an empty path. And it might sound
a bit weird to users with the quoted 'none'. Maybe the first sentence is
already enough or you can reword the message a bit?

> +    return '';

Should we cache the fact that there is no drive too? Would potentially
avoid printing the warning multiple times and testing again.

>  }
>  
>  sub get_iso_path {