agent: add GetGuestDetails gRPC function

To get memory hotplug align boundary, need read
/sys/devices/system/memory/block_size_bytes in guest.
Add a function to do this and we can also extend to
get other details in the future.

Fixes #354

Signed-off-by: Zichang Lin <[email protected]>

grpc.go

@@ -1303,3 +1303,18 @@ func (a *agentGRPC) OnlineCPUMem(ctx context.Context, req *pb.OnlineCPUMemReques
 func (a *agentGRPC) ReseedRandomDev(ctx context.Context, req *pb.ReseedRandomDevRequest) (*gpb.Empty, error) {
 	return emptyResp, reseedRNG(req.Data)
 }
+
+func (a *agentGRPC) GetGuestDetails(ctx context.Context, req *pb.GuestDetailsRequest) (*pb.GuestDetailsResponse, error) {
+	var details pb.GuestDetailsResponse
+	if req.MemBlockSize {
+		data, err := ioutil.ReadFile("/sys/devices/system/memory/block_size_bytes")
+		if err != nil {
+			return nil, err
+		}
+		details.MemBlockSizeBytes, err = strconv.ParseUint(string(data[:len(data)-1]), 16, 64)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &details, nil
+}

grpc_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/stretchr/testify/assert"
+	"strconv"
 	"sync"
 )
 
@@ -620,3 +621,27 @@ func TestMultiWaitProcess(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestGetGuestDetails(t *testing.T) {
+	assert := assert.New(t)
+	a := &agentGRPC{
+		sandbox: &sandbox{
+			containers: make(map[string]*container),
+		},
+	}
+
+	req := &pb.GuestDetailsRequest{
+		MemBlockSize: true,
+	}
+
+	resp, err := a.GetGuestDetails(context.TODO(), req)
+	assert.NoError(err)
+
+	data, err := ioutil.ReadFile("/sys/devices/system/memory/block_size_bytes")
+	assert.NoError(err)
+
+	size, err := strconv.ParseUint(string(data[:len(data)-1]), 16, 64)
+	assert.NoError(err)
+
+	assert.Equal(resp.MemBlockSizeBytes, size)
+}