[pve-devel] [PATCH qemu-server v3] cd rom handling: return a clearer error when there is no cd rom drive

[Stefan Sterz <s.sterz@proxmox.com>]

when a vm is configured to use a physical cd rom drive but there is no
such drive a cryptic "uninitialized value" error is thrown. this is
due to `$path` not being defined in `sub
print_drive_commandline_full` in this case. warn that no cd rom drive
is available instead.

note that the error was basically cosmetic as the vm would start just
fine.

forum thread: https://forum.proxmox.com/threads/119592/

Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>
---
changes from v2 (thanks @ Fiona Ebner):

* added newline to message
* cache the fact that no drive is available so we warn only once
* adjusted error message again

changes from v1: 

* make the error message more concise. 
* use shorter forum link for better formatting in commit message 
  (thanks @ Fiona Ebner).

 PVE/QemuServer.pm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index dd6ea3e..11626cf 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -1287,11 +1287,14 @@ sub option_exists {
 my $cdrom_path;
 sub get_cdrom_path {
 
-    return  $cdrom_path if $cdrom_path;
+    return  $cdrom_path if defined($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 "no physical CD-ROM available\n";
+    return $cdrom_path = '';
 }
 
 sub get_iso_path {
-- 
2.30.2