cg: add a unit test TestUidGid for cgroup_{set,get}_uid_gid()

cg.go

@@ -13,6 +13,7 @@ import "C"
 import (
 	"errors"
 	"runtime"
+	"strconv"
 	"unsafe"
 )
 
@@ -561,3 +562,22 @@ func _err(num C.int) error {
 	// There's a lot. We'll create them as they come
 	return errors.New(C.GoString(C.cgroup_strerror(num)))
 }
+
+// simple helpers to get UID or GID from a given string
+func stringToUID(uidStr string) UID {
+	intVal, err := strconv.Atoi(uidStr)
+	if err != nil {
+		return UID(0)
+	}
+
+	return UID(intVal)
+}
+
+func stringToGID(gidStr string) GID {
+	intVal, err := strconv.Atoi(gidStr)
+	if err != nil {
+		return GID(0)
+	}
+
+	return GID(intVal)
+}

cg_test.go

@@ -0,0 +1,41 @@
+package cgroup
+
+import (
+	"os/user"
+	"testing"
+)
+
+func TestUidGid(t *testing.T) {
+	Init()
+
+	var wantTaskUid, wantCtrlUid UID
+	var wantTaskGid, wantCtrlGid GID
+
+	curUser, err := user.Current()
+	if err == nil {
+		wantTaskUid = stringToUID(curUser.Uid)
+		wantTaskGid = stringToGID(curUser.Gid)
+		wantCtrlUid = stringToUID(curUser.Uid)
+		wantCtrlGid = stringToGID(curUser.Gid)
+	} else {
+		t.Logf("cannot get the current user. fall back to 0.\n")
+		wantTaskUid, wantTaskGid, wantCtrlUid, wantCtrlGid = 0, 0, 0, 0
+	}
+
+	cg := NewCgroup("test_cgroup")
+	if err := cg.SetUIDGID(wantTaskUid, wantTaskGid, wantCtrlUid, wantCtrlGid); err != nil {
+		t.Fatalf("cannot set cgroup uids/gids: %v\n", err)
+	}
+
+	gotTaskUid, gotTaskGid, gotCtrlUid, gotCtrlGid, err := cg.GetUIDGID()
+	if err != nil {
+		t.Fatalf("cannot get cgroup uids/gids: %v\n", err)
+	}
+
+	if wantTaskUid != gotTaskUid || wantTaskGid != gotTaskGid ||
+		wantCtrlUid != gotCtrlUid || wantCtrlGid != gotCtrlGid {
+		t.Fatalf("wanted (%d,%d,%d,%d), got (%d,%d,%d,%d)\n",
+			wantTaskUid, wantTaskGid, wantCtrlUid, wantCtrlGid,
+			gotTaskUid, gotTaskGid, gotCtrlUid, gotCtrlGid)
+	}
+}