[PATCH v3 1/1] golang/xenlight: add NameToDomid and DomidToName util functions

[Nick Rosbrook <rosbrookn@xxxxxxxxx>]

Many exported functions in xenlight require a domid as an argument. Make
it easier for package users to use these functions by adding wrappers
for the libxl utility functions libxl_name_to_domid and
libxl_domid_to_name.

Signed-off-by: Nick Rosbrook <rosbrookn@xxxxxxxxxxxx>
---
 tools/golang/xenlight/xenlight.go | 40 ++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/tools/golang/xenlight/xenlight.go 
b/tools/golang/xenlight/xenlight.go
index 6b4f492550..742e5e11f1 100644
--- a/tools/golang/xenlight/xenlight.go
+++ b/tools/golang/xenlight/xenlight.go
@@ -21,13 +21,15 @@ package xenlight
 #cgo LDFLAGS: -lxenlight -lyajl -lxentoollog
 #include <stdlib.h>
 #include <libxl.h>
+#include <libxl_utils.h>
+
+#define INVALID_DOMID_TYPED ((uint32_t) INVALID_DOMID)
 
 static const libxl_childproc_hooks childproc_hooks = { .chldowner = 
libxl_sigchld_owner_mainloop };
 
 void xenlight_set_chldproc(libxl_ctx *ctx) {
        libxl_childproc_setmode(ctx, &childproc_hooks, NULL);
 }
-
 */
 import "C"
 
@@ -75,6 +77,10 @@ var libxlErrors = map[Error]string{
        ErrorFeatureRemoved:               "Feature removed",
 }
 
+const (
+       DomidInvalid Domid = Domid(C.INVALID_DOMID_TYPED)
+)
+
 func (e Error) Error() string {
        if s, ok := libxlErrors[e]; ok {
                return s
@@ -190,6 +196,38 @@ func (ctx *Context) Close() error {
 
 type Domid uint32
 
+// NameToDomid returns the Domid for a domain, given its name, if it exists.
+//
+// NameToDomid does not guarantee that the domid associated with name at
+// the time NameToDomid is called is the same as the domid associated with
+// name at the time NameToDomid returns.
+func (Ctx *Context) NameToDomid(name string) (Domid, error) {
+       var domid C.uint32_t
+
+       cname := C.CString(name)
+       defer C.free(unsafe.Pointer(cname))
+
+       if ret := C.libxl_name_to_domid(Ctx.ctx, cname, &domid); ret != 0 {
+               return DomidInvalid, Error(ret)
+       }
+
+       return Domid(domid), nil
+}
+
+// DomidToName returns the name for a domain, given its domid. If there
+// is no domain with the given domid, DomidToName will return the empty
+// string.
+//
+// DomidToName does not guarantee that the name (if any) associated with domid
+// at the time DomidToName is called is the same as the name (if any) 
associated
+// with domid at the time DomidToName returns.
+func (Ctx *Context) DomidToName(domid Domid) string {
+       cname := C.libxl_domid_to_name(Ctx.ctx, C.uint32_t(domid))
+       defer C.free(unsafe.Pointer(cname))
+
+       return C.GoString(cname)
+}
+
 // Devid is a device ID.
 type Devid int
 
-- 
2.17.1