golang/xenlight: Do proper nil / NULL conversions for builtin Bitmap type

Similar to the autogenerated types, but for `builtin` Bitmap type.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Nick Rosbrook <rosbrookn@ainfosec.com>

diff --git a/tools/golang/xenlight/xenlight.go b/tools/golang/xenlight/xenlight.go
index 24b1e022ff5659a5b5713e4d921bbe8a49b93593..b1587b964f3dedd3f7be9305cde4dbce490b5073 100644 (file)
--- a/tools/golang/xenlight/xenlight.go
+++ b/tools/golang/xenlight/xenlight.go
@@ -396,15 +396,17 @@ type Bitmap struct {
 }
 
 func (bm *Bitmap) fromC(cbm *C.libxl_bitmap) error {
-       // Alloc a Go slice for the bytes
-       size := int(cbm.size)
-       bm.bitmap = make([]C.uint8_t, size)
+       bm.bitmap = nil
+       if size := int(cbm.size); size > 0 {
+               // Alloc a Go slice for the bytes
+               bm.bitmap = make([]C.uint8_t, size)
 
-       // Make a slice pointing to the C array
-       cs := (*[1 << 30]C.uint8_t)(unsafe.Pointer(cbm._map))[:size:size]
+               // Make a slice pointing to the C array
+               cs := (*[1 << 30]C.uint8_t)(unsafe.Pointer(cbm._map))[:size:size]
 
-       // And copy the C array into the Go array
-       copy(bm.bitmap, cs)
+               // And copy the C array into the Go array
+               copy(bm.bitmap, cs)
+       }
 
        return nil
 }
@@ -412,10 +414,12 @@ func (bm *Bitmap) fromC(cbm *C.libxl_bitmap) error {
 func (bm *Bitmap) toC(cbm *C.libxl_bitmap) error {
        size := len(bm.bitmap)
        cbm.size = C.uint32_t(size)
-       cbm._map = (*C.uint8_t)(C.malloc(C.ulong(cbm.size) * C.sizeof_uint8_t))
-       cs := (*[1 << 31]C.uint8_t)(unsafe.Pointer(cbm._map))[:size:size]
+       if cbm.size > 0 {
+               cbm._map = (*C.uint8_t)(C.malloc(C.ulong(cbm.size) * C.sizeof_uint8_t))
+               cs := (*[1 << 31]C.uint8_t)(unsafe.Pointer(cbm._map))[:size:size]
 
-       copy(cs, bm.bitmap)
+               copy(cs, bm.bitmap)
+       }
 
        return nil
 }