tree-wide: use -EINVAL for enum invalid values

As suggested in https://github.com/systemd/systemd/pull/11484#issuecomment-775288617.

This does not touch anything exposed in src/systemd. Changing the defines there
would be a compatibility break.

Note that tests are broken after this commit. They will be fixed in the next one.

src/network/netdev/bareudp.h

@@ -15,7 +15,7 @@ typedef enum BareUDPProtocol {
         BARE_UDP_PROTOCOL_MPLS_UC = ETH_P_MPLS_UC,
         BARE_UDP_PROTOCOL_MPLS_MC = ETH_P_MPLS_MC,
         _BARE_UDP_PROTOCOL_MAX,
-        _BARE_UDP_PROTOCOL_INVALID = -1
+        _BARE_UDP_PROTOCOL_INVALID = -EINVAL,
 } BareUDPProtocol;
 
 struct BareUDP {

src/network/netdev/bridge.h

@@ -35,7 +35,7 @@ typedef enum MulticastRouter {
         MULTICAST_ROUTER_PERMANENT       = MDB_RTR_TYPE_PERM,
         MULTICAST_ROUTER_TEMPORARY       = MDB_RTR_TYPE_TEMP,
         _MULTICAST_ROUTER_MAX,
-        _MULTICAST_ROUTER_INVALID = -1,
+        _MULTICAST_ROUTER_INVALID = -EINVAL,
 } MulticastRouter;
 
 DEFINE_NETDEV_CAST(BRIDGE, Bridge);

src/network/netdev/fou-tunnel.h

@@ -12,7 +12,7 @@ typedef enum FooOverUDPEncapType {
         NETDEV_FOO_OVER_UDP_ENCAP_DIRECT = FOU_ENCAP_DIRECT,
         NETDEV_FOO_OVER_UDP_ENCAP_GUE = FOU_ENCAP_GUE,
         _NETDEV_FOO_OVER_UDP_ENCAP_MAX,
-        _NETDEV_FOO_OVER_UDP_ENCAP_INVALID = -1,
+        _NETDEV_FOO_OVER_UDP_ENCAP_INVALID = -EINVAL,
 } FooOverUDPEncapType;
 
 typedef struct FouTunnel {

src/network/netdev/geneve.h

@@ -14,7 +14,7 @@ typedef enum GeneveDF {
         NETDEV_GENEVE_DF_YES = GENEVE_DF_SET,
         NETDEV_GENEVE_DF_INHERIT = GENEVE_DF_INHERIT,
         _NETDEV_GENEVE_DF_MAX,
-        _NETDEV_GENEVE_DF_INVALID = -1
+        _NETDEV_GENEVE_DF_INVALID = -EINVAL,
 } GeneveDF;
 
 struct Geneve {

src/network/netdev/l2tp-tunnel.h

@@ -12,14 +12,14 @@ typedef enum L2tpL2specType {
         NETDEV_L2TP_L2SPECTYPE_NONE = L2TP_L2SPECTYPE_NONE,
         NETDEV_L2TP_L2SPECTYPE_DEFAULT = L2TP_L2SPECTYPE_DEFAULT,
         _NETDEV_L2TP_L2SPECTYPE_MAX,
-        _NETDEV_L2TP_L2SPECTYPE_INVALID = -1,
+        _NETDEV_L2TP_L2SPECTYPE_INVALID = -EINVAL,
 } L2tpL2specType;
 
 typedef enum L2tpEncapType {
         NETDEV_L2TP_ENCAPTYPE_UDP = L2TP_ENCAPTYPE_UDP,
         NETDEV_L2TP_ENCAPTYPE_IP = L2TP_ENCAPTYPE_IP,
         _NETDEV_L2TP_ENCAPTYPE_MAX,
-        _NETDEV_L2TP_ENCAPTYPE_INVALID = -1,
+        _NETDEV_L2TP_ENCAPTYPE_INVALID = -EINVAL,
 } L2tpEncapType;
 
 typedef enum L2tpLocalAddressType {
@@ -27,7 +27,7 @@ typedef enum L2tpLocalAddressType {
         NETDEV_L2TP_LOCAL_ADDRESS_STATIC,
         NETDEV_L2TP_LOCAL_ADDRESS_DYNAMIC,
         _NETDEV_L2TP_LOCAL_ADDRESS_MAX,
-        _NETDEV_L2TP_LOCAL_ADDRESS_INVALID = -1,
+        _NETDEV_L2TP_LOCAL_ADDRESS_INVALID = -EINVAL,
 } L2tpLocalAddressType;
 
 typedef struct L2tpTunnel L2tpTunnel;

src/network/netdev/netdev.h

@@ -85,7 +85,7 @@ typedef enum NetDevKind {
         NETDEV_KIND_BAREUDP,
         _NETDEV_KIND_MAX,
         _NETDEV_KIND_TUNNEL, /* Used by config_parse_stacked_netdev() */
-        _NETDEV_KIND_INVALID = -1
+        _NETDEV_KIND_INVALID = -EINVAL,
 } NetDevKind;
 
 typedef enum NetDevState {
@@ -95,7 +95,7 @@ typedef enum NetDevState {
         NETDEV_STATE_READY,
         NETDEV_STATE_LINGER,
         _NETDEV_STATE_MAX,
-        _NETDEV_STATE_INVALID = -1,
+        _NETDEV_STATE_INVALID = -EINVAL,
 } NetDevState;
 
 typedef enum NetDevCreateType {
@@ -104,7 +104,7 @@ typedef enum NetDevCreateType {
         NETDEV_CREATE_STACKED,
         NETDEV_CREATE_AFTER_CONFIGURED,
         _NETDEV_CREATE_MAX,
-        _NETDEV_CREATE_INVALID = -1,
+        _NETDEV_CREATE_INVALID = -EINVAL,
 } NetDevCreateType;
 
 typedef struct Manager Manager;

src/network/netdev/tunnel.h

@@ -12,13 +12,13 @@ typedef enum Ip6TnlMode {
         NETDEV_IP6_TNL_MODE_IPIP6,
         NETDEV_IP6_TNL_MODE_ANYIP6,
         _NETDEV_IP6_TNL_MODE_MAX,
-        _NETDEV_IP6_TNL_MODE_INVALID = -1,
+        _NETDEV_IP6_TNL_MODE_INVALID = -EINVAL,
 } Ip6TnlMode;
 
 typedef enum IPv6FlowLabel {
         NETDEV_IPV6_FLOWLABEL_INHERIT = 0xFFFFF + 1,
         _NETDEV_IPV6_FLOWLABEL_MAX,
-        _NETDEV_IPV6_FLOWLABEL_INVALID = -1,
+        _NETDEV_IPV6_FLOWLABEL_INVALID = -EINVAL,
 } IPv6FlowLabel;
 
 typedef struct Tunnel {

src/network/netdev/vxlan.h

@@ -16,7 +16,7 @@ typedef enum VxLanDF {
         NETDEV_VXLAN_DF_YES = VXLAN_DF_SET,
         NETDEV_VXLAN_DF_INHERIT = VXLAN_DF_INHERIT,
         _NETDEV_VXLAN_DF_MAX,
-        _NETDEV_VXLAN_DF_INVALID = -1
+        _NETDEV_VXLAN_DF_INVALID = -EINVAL,
 } VxLanDF;
 
 struct VxLan {