[PATCH v2 1/3] tools/golang: When returning pointers, actually allocate structrues

[George Dunlap <george.dunlap@xxxxxxxxx>]

In a handful of cases, it was decided to return a pointer to a
structure rather than the plain structure itself, due to the size.
However, in these cases the structure was never allocated, leading to
a nil pointer exception when calling the relevant `fromC` method.

Allocate structures before attempting to fill them in.

Fixes: 453713b1750 ("golang/xenlight: Add host-related functionality")
Reported-by: Tobias Fitschen <tobias.fitschen@xxxxxxxxx>
Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxx>
Tested-by: Tobias Fitschen <tobias.fitschen@xxxxxxxxx>
---
v2:
 - Added Fixes: tag
 - Added Tested-by tag

NB this is a candidate for backport.

CC: Nick Rosbrook <rosbrookn@xxxxxxxxx>
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/golang/xenlight/xenlight.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/golang/xenlight/xenlight.go 
b/tools/golang/xenlight/xenlight.go
index a45c636952..d793f172e5 100644
--- a/tools/golang/xenlight/xenlight.go
+++ b/tools/golang/xenlight/xenlight.go
@@ -999,6 +999,7 @@ func (ctx *Context) GetPhysinfo() (physinfo *Physinfo, err 
error) {
                err = Error(ret)
                return
        }
+       physinfo = &Physinfo{}
        err = physinfo.fromC(&cphys)
 
        return
@@ -1010,6 +1011,7 @@ func (ctx *Context) GetVersionInfo() (info *VersionInfo, 
err error) {
 
        cinfo = C.libxl_get_version_info(ctx.ctx)
 
+       info = &VersionInfo{}
        err = info.fromC(cinfo)
 
        return
@@ -1027,6 +1029,7 @@ func (ctx *Context) DomainInfo(Id Domid) (di *Dominfo, 
err error) {
                return
        }
 
+       di = &Dominfo{}
        err = di.fromC(&cdi)
 
        return
-- 
2.25.1