[PATCH v3 0/1] More wrappers for xenlight Go package

[PATCH v3 0/1] More wrappers for xenlight Go package

[Nick Rosbrook]

This series adds wrappers to the xenlight package for various libxl
functions, which are now trivial to add with the generated types and 
marshaling helpers. In particular, these are functions that would allow
redctl to begin making the transition to using the xenlight package. For 
reference, I have started an experimental branch where I am using these
functions in redctl [1].

[1] https://gitlab.com/enr0n/redctl/-/blob/1bdf7b515654cc030e095f3a630a24530f930c00/internal/server/xenlight_xen_driver.go

Changes in v2:
 - Define constant DomidInvalid in first patch for use in NameToDomid
 - Add more detail to function comments

Changes in v3:
 - Define INVALID_DOMID_TYPED in C preamble so that the Go const
   DomidInvalid is always in-sync with the libxl definition.

Nick Rosbrook (1):
  golang/xenlight: add NameToDomid and DomidToName util functions

 tools/golang/xenlight/xenlight.go | 40 ++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

-- 
2.17.1

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

[Nick Rosbrook]

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@ainfosec.com>
---
 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

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

[George Dunlap]

> On May 13, 2020, at 1:55 AM, Nick Rosbrook <rosbrookn@gmail.com> wrote:
> 
> 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@ainfosec.com>

Looks good, thanks!

Reviewed-by: George Dunlap <george.dunlap@citrix.com>