[PATCH proxmox-ve-rs 2/2] ve-config: guest: add fallback enum variant

[Stefan Hanreich <s.hanreich@proxmox.com>]

In order for ve-config to stay forward-compatible with the addition of
new network interface types, introduce a fallback variant to contain
any potential unknown variants that may be introduced in the future.
Since the netX properties in qemu-server use KeyAliasInfo, and the
struct does not provide the possibility of allowing arbitrary keys,
this does not allow using arbitrary models when using the short form -
which is currently prevalent in the configuration files.

Signed-off-by: Stefan Hanreich <s.hanreich@proxmox.com>
---

Notes:
    Practically not really an improvement, but I had it initially and
    thought it wouldn't hurt to include it in the series nonetheles. If
    not desired or deemed to useless, this patch can be dropped when
    applying.

 Cargo.toml                        |  1 +
 proxmox-ve-config/Cargo.toml      |  1 +
 proxmox-ve-config/src/guest/vm.rs | 11 +++++++++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 4655b178..2f9058dd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,6 +24,7 @@ regex = "1.7"
 serde = { version = "1" }
 thiserror = "2.0.0"
 
+proxmox-fixed-string = { version = "0.1.1" }
 proxmox-frr = { version = "0.5.1", path = "proxmox-frr" }
 proxmox-network-types = { version = "1.1.2" }
 proxmox-schema = { version = "5" }
diff --git a/proxmox-ve-config/Cargo.toml b/proxmox-ve-config/Cargo.toml
index 7e3939d4..3d5aa9eb 100644
--- a/proxmox-ve-config/Cargo.toml
+++ b/proxmox-ve-config/Cargo.toml
@@ -19,6 +19,7 @@ serde = { workspace = true, features = [ "derive" ] }
 serde_json = "1"
 
 proxmox-base64 = "1"
+proxmox-fixed-string.workspace = true
 proxmox-frr = { workspace = true, optional = true }
 proxmox-network-types = { workspace = true, features = [ "api-types" ] }
 proxmox-schema = { workspace = true, features = [ "api-types" ] }
diff --git a/proxmox-ve-config/src/guest/vm.rs b/proxmox-ve-config/src/guest/vm.rs
index cebcb9e6..3ce04c73 100644
--- a/proxmox-ve-config/src/guest/vm.rs
+++ b/proxmox-ve-config/src/guest/vm.rs
@@ -2,7 +2,8 @@ use std::collections::BTreeMap;
 use std::io;
 use std::str::FromStr;
 
-use anyhow::{Error, bail};
+use anyhow::{Context, Error, bail};
+use proxmox_fixed_string::FixedString;
 use serde::Deserialize;
 
 use proxmox_network_types::ip_address::{Ipv4Cidr, Ipv6Cidr};
@@ -32,6 +33,7 @@ pub enum NetworkDeviceModel {
     Ne2kIsa,
     Ne2kPci,
     Pcnet,
+    UnknownEnumValue(FixedString),
 }
 
 proxmox_serde::forward_deserialize_to_from_str!(NetworkDeviceModel);
@@ -56,7 +58,12 @@ impl FromStr for NetworkDeviceModel {
             "ne2k_isa" => Ok(NetworkDeviceModel::Ne2kIsa),
             "ne2k_pci" => Ok(NetworkDeviceModel::Ne2kPci),
             "pcnet" => Ok(NetworkDeviceModel::Pcnet),
-            _ => bail!("Invalid network device model: {s}"),
+            _ => {
+                let unknown_variant = FixedString::try_from(s)
+                    .with_context(|| format!("unable to parse network device model {s}"))?;
+
+                Ok(NetworkDeviceModel::UnknownEnumValue(unknown_variant))
+            }
         }
     }
 }
-- 
2.47.3