[Xen-changelog] [xen staging] golang/xenlight: Fix handling of marshalling of empty elements for keyed unions

[patchbot@xxxxxxx]

commit 99f1c935190986068a36fb5e78a00e6b71b08f25
Author:     George Dunlap <george.dunlap@xxxxxxxxxx>
AuthorDate: Thu Mar 5 11:34:07 2020 +0000
Commit:     George Dunlap <george.dunlap@xxxxxxxxxx>
CommitDate: Mon Mar 9 14:36:29 2020 +0000

    golang/xenlight: Fix handling of marshalling of empty elements for keyed 
unions
    
    Keyed types in libxl_types.idl can have elements of type 'None'.  The
    golang type generator (correctly) don't implement any union types for
    these empty elements.  However, the toC and fromC helper generators
    incorrectly treat these elements as invalid.
    
    Consider for example, libxl_channelinfo.  The idl contains the
    following keyed element:
    
        ("u", KeyedUnion(None, libxl_channel_connection, "connection",
               [("unknown", None),
                ("pty", Struct(None, [("path", string),])),
                ("socket", None),
               ])),
    
    But the toC marshaller currently looks like this:
    
            switch x.Connection {
            case ChannelConnectionPty:
                    tmp, ok := x.ConnectionUnion.(ChannelinfoConnectionUnionPty)
                    if !ok {
                            return errors.New("wrong type for union key 
connection")
                    }
                    var pty C.libxl_channelinfo_connection_union_pty
                    if tmp.Path != "" {
                            pty.path = C.CString(tmp.Path)
                    }
                    ptyBytes := C.GoBytes(unsafe.Pointer(&pty), 
C.sizeof_libxl_channelinfo_connection_union_pty)
                    copy(xc.u[:], ptyBytes)
            default:
                    return fmt.Errorf("invalid union key '%v'", x.Connection)
            }
    
    Which means toC() will fail for ChannelConnectionUnknown or
    ChannelConnectionSocket.
    
    Modify the generator to handle keyed union elements of type 'None'.
    For fromC, set the value to 'nil'; for toC, leave things as-is.
    
    Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Reviewed-by: Nick Rosbrook <rosbrookn@xxxxxxxxxxxx>
---
 tools/golang/xenlight/gengotypes.py  | 19 ++++++++++++++-----
 tools/golang/xenlight/helpers.gen.go | 28 ++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/tools/golang/xenlight/gengotypes.py 
b/tools/golang/xenlight/gengotypes.py
index f81271f3c0..50dada309b 100644
--- a/tools/golang/xenlight/gengotypes.py
+++ b/tools/golang/xenlight/gengotypes.py
@@ -335,6 +335,7 @@ def xenlight_golang_union_from_C(ty = None, union_name = 
'', struct_name = ''):
     gokeyname = xenlight_golang_fmt_name(keyname)
     keytype   = ty.keyvar.type.typename
     gokeytype = xenlight_golang_fmt_name(keytype)
+    field_name = xenlight_golang_fmt_name('{}_union'.format(keyname))
 
     interface_name = '{}_{}_union'.format(struct_name, keyname)
     interface_name = xenlight_golang_fmt_name(interface_name, exported=False)
@@ -351,11 +352,11 @@ def xenlight_golang_union_from_C(ty = None, union_name = 
'', struct_name = ''):
 
         # Add to list of cases to make for the switch
         # statement below.
+        cases[f.name] = (val, f.type)
+
         if f.type is None:
             continue
 
-        cases[f.name] = val
-
         # Define fromC func for 'union' struct.
         typename   = '{}_{}_union_{}'.format(struct_name,keyname,f.name)
         gotypename = xenlight_golang_fmt_name(typename)
@@ -382,9 +383,15 @@ def xenlight_golang_union_from_C(ty = None, union_name = 
'', struct_name = ''):
 
     # Create switch statement to determine which 'union element'
     # to populate in the Go struct.
-    for case_name, case_val in cases.items():
+    for case_name, case_tuple in cases.items():
+        (case_val, case_type) = case_tuple
+
         s += 'case {}:\n'.format(case_val)
 
+        if case_type is None:
+            s += "x.{} = nil\n".format(field_name)
+            continue
+
         gotype = '{}_{}_union_{}'.format(struct_name,keyname,case_name)
         gotype = xenlight_golang_fmt_name(gotype)
         goname = '{}_{}'.format(keyname,case_name)
@@ -394,7 +401,6 @@ def xenlight_golang_union_from_C(ty = None, union_name = 
'', struct_name = ''):
         s += 'if err := {}.fromC(xc);'.format(goname)
         s += 'err != nil {{\n return fmt.Errorf("converting field {}: %v", 
err) \n}}\n'.format(goname)
 
-        field_name = xenlight_golang_fmt_name('{}_union'.format(keyname))
         s += 'x.{} = {}\n'.format(field_name, goname)
 
     # End switch statement
@@ -551,10 +557,13 @@ def xenlight_golang_union_to_C(ty = None, union_name = '',
     for f in ty.fields:
         key_val = '{}_{}'.format(keytype, f.name)
         key_val = xenlight_golang_fmt_name(key_val)
+
+        s += 'case {}:\n'.format(key_val)
+
         if f.type is None:
+            s += "break\n"
             continue
 
-        s += 'case {}:\n'.format(key_val)
         cgotype = '{}_{}_union_{}'.format(struct_name,keyname,f.name)
         gotype  = xenlight_golang_fmt_name(cgotype)
 
diff --git a/tools/golang/xenlight/helpers.gen.go 
b/tools/golang/xenlight/helpers.gen.go
index 37cd3b8249..344ce9a461 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -493,12 +493,16 @@ func (x *Channelinfo) fromC(xc *C.libxl_channelinfo) 
error {
        x.Rref = int(xc.rref)
        x.Connection = ChannelConnection(xc.connection)
        switch x.Connection {
+       case ChannelConnectionUnknown:
+               x.ConnectionUnion = nil
        case ChannelConnectionPty:
                var connectionPty ChannelinfoConnectionUnionPty
                if err := connectionPty.fromC(xc); err != nil {
                        return fmt.Errorf("converting field connectionPty: %v", 
err)
                }
                x.ConnectionUnion = connectionPty
+       case ChannelConnectionSocket:
+               x.ConnectionUnion = nil
        default:
                return fmt.Errorf("invalid union key '%v'", x.Connection)
        }
@@ -537,6 +541,8 @@ func (x *Channelinfo) toC(xc *C.libxl_channelinfo) (err 
error) {
        xc.rref = C.int(x.Rref)
        xc.connection = C.libxl_channel_connection(x.Connection)
        switch x.Connection {
+       case ChannelConnectionUnknown:
+               break
        case ChannelConnectionPty:
                tmp, ok := x.ConnectionUnion.(ChannelinfoConnectionUnionPty)
                if !ok {
@@ -548,6 +554,8 @@ func (x *Channelinfo) toC(xc *C.libxl_channelinfo) (err 
error) {
                }
                ptyBytes := C.GoBytes(unsafe.Pointer(&pty), 
C.sizeof_libxl_channelinfo_connection_union_pty)
                copy(xc.u[:], ptyBytes)
+       case ChannelConnectionSocket:
+               break
        default:
                return fmt.Errorf("invalid union key '%v'", x.Connection)
        }
@@ -1223,6 +1231,8 @@ func (x *DomainBuildInfo) fromC(xc 
*C.libxl_domain_build_info) error {
                        return fmt.Errorf("converting field typePvh: %v", err)
                }
                x.TypeUnion = typePvh
+       case DomainTypeInvalid:
+               x.TypeUnion = nil
        default:
                return fmt.Errorf("invalid union key '%v'", x.Type)
        }
@@ -1723,6 +1733,8 @@ func (x *DomainBuildInfo) toC(xc 
*C.libxl_domain_build_info) (err error) {
                }
                pvhBytes := C.GoBytes(unsafe.Pointer(&pvh), 
C.sizeof_libxl_domain_build_info_type_union_pvh)
                copy(xc.u[:], pvhBytes)
+       case DomainTypeInvalid:
+               break
        default:
                return fmt.Errorf("invalid union key '%v'", x.Type)
        }
@@ -2650,6 +2662,10 @@ func (x *DeviceChannel) fromC(xc 
*C.libxl_device_channel) error {
        x.Name = C.GoString(xc.name)
        x.Connection = ChannelConnection(xc.connection)
        switch x.Connection {
+       case ChannelConnectionUnknown:
+               x.ConnectionUnion = nil
+       case ChannelConnectionPty:
+               x.ConnectionUnion = nil
        case ChannelConnectionSocket:
                var connectionSocket DeviceChannelConnectionUnionSocket
                if err := connectionSocket.fromC(xc); err != nil {
@@ -2690,6 +2706,10 @@ func (x *DeviceChannel) toC(xc *C.libxl_device_channel) 
(err error) {
        }
        xc.connection = C.libxl_channel_connection(x.Connection)
        switch x.Connection {
+       case ChannelConnectionUnknown:
+               break
+       case ChannelConnectionPty:
+               break
        case ChannelConnectionSocket:
                tmp, ok := 
x.ConnectionUnion.(DeviceChannelConnectionUnionSocket)
                if !ok {
@@ -4376,6 +4396,8 @@ func (x *Event) fromC(xc *C.libxl_event) error {
                        return fmt.Errorf("converting field typeDomainShutdown: 
%v", err)
                }
                x.TypeUnion = typeDomainShutdown
+       case EventTypeDomainDeath:
+               x.TypeUnion = nil
        case EventTypeDiskEject:
                var typeDiskEject EventTypeUnionDiskEject
                if err := typeDiskEject.fromC(xc); err != nil {
@@ -4388,6 +4410,8 @@ func (x *Event) fromC(xc *C.libxl_event) error {
                        return fmt.Errorf("converting field 
typeOperationComplete: %v", err)
                }
                x.TypeUnion = typeOperationComplete
+       case EventTypeDomainCreateConsoleAvailable:
+               x.TypeUnion = nil
        default:
                return fmt.Errorf("invalid union key '%v'", x.Type)
        }
@@ -4454,6 +4478,8 @@ func (x *Event) toC(xc *C.libxl_event) (err error) {
                domain_shutdown.shutdown_reason = C.uint8_t(tmp.ShutdownReason)
                domain_shutdownBytes := 
C.GoBytes(unsafe.Pointer(&domain_shutdown), 
C.sizeof_libxl_event_type_union_domain_shutdown)
                copy(xc.u[:], domain_shutdownBytes)
+       case EventTypeDomainDeath:
+               break
        case EventTypeDiskEject:
                tmp, ok := x.TypeUnion.(EventTypeUnionDiskEject)
                if !ok {
@@ -4477,6 +4503,8 @@ func (x *Event) toC(xc *C.libxl_event) (err error) {
                operation_complete.rc = C.int(tmp.Rc)
                operation_completeBytes := 
C.GoBytes(unsafe.Pointer(&operation_complete), 
C.sizeof_libxl_event_type_union_operation_complete)
                copy(xc.u[:], operation_completeBytes)
+       case EventTypeDomainCreateConsoleAvailable:
+               break
        default:
                return fmt.Errorf("invalid union key '%v'", x.Type)
        }
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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