Clean up unix vs linux usage

FreeBSD does not support cgroups or namespaces, which the code suggested, and is not supported
in runc anyway right now. So clean up the file naming to use `_linux` where appropriate.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

libcontainer/configs/config_linux_test.go

@@ -0,0 +1,130 @@
+package configs
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func loadConfig(name string) (*Config, error) {
+	f, err := os.Open(filepath.Join("../sample_configs", name))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var container *Config
+	if err := json.NewDecoder(f).Decode(&container); err != nil {
+		return nil, err
+	}
+
+	// Check that a config doesn't contain extra fields
+	var configMap, abstractMap map[string]interface{}
+
+	if _, err := f.Seek(0, 0); err != nil {
+		return nil, err
+	}
+
+	if err := json.NewDecoder(f).Decode(&abstractMap); err != nil {
+		return nil, err
+	}
+
+	configData, err := json.Marshal(&container)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := json.Unmarshal(configData, &configMap); err != nil {
+		return nil, err
+	}
+
+	for k := range configMap {
+		delete(abstractMap, k)
+	}
+
+	if len(abstractMap) != 0 {
+		return nil, fmt.Errorf("unknown fields: %s", abstractMap)
+	}
+
+	return container, nil
+}
+
+func TestRemoveNamespace(t *testing.T) {
+	ns := Namespaces{
+		{Type: NEWNET},
+	}
+	if !ns.Remove(NEWNET) {
+		t.Fatal("NEWNET was not removed")
+	}
+	if len(ns) != 0 {
+		t.Fatalf("namespaces should have 0 items but reports %d", len(ns))
+	}
+}
+
+func TestHostRootUIDNoUSERNS(t *testing.T) {
+	config := &Config{
+		Namespaces: Namespaces{},
+	}
+	uid, err := config.HostRootUID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if uid != 0 {
+		t.Fatalf("expected uid 0 with no USERNS but received %d", uid)
+	}
+}
+
+func TestHostRootUIDWithUSERNS(t *testing.T) {
+	config := &Config{
+		Namespaces: Namespaces{{Type: NEWUSER}},
+		UidMappings: []IDMap{
+			{
+				ContainerID: 0,
+				HostID:      1000,
+				Size:        1,
+			},
+		},
+	}
+	uid, err := config.HostRootUID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if uid != 1000 {
+		t.Fatalf("expected uid 1000 with no USERNS but received %d", uid)
+	}
+}
+
+func TestHostRootGIDNoUSERNS(t *testing.T) {
+	config := &Config{
+		Namespaces: Namespaces{},
+	}
+	uid, err := config.HostRootGID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if uid != 0 {
+		t.Fatalf("expected gid 0 with no USERNS but received %d", uid)
+	}
+}
+
+func TestHostRootGIDWithUSERNS(t *testing.T) {
+	config := &Config{
+		Namespaces: Namespaces{{Type: NEWUSER}},
+		GidMappings: []IDMap{
+			{
+				ContainerID: 0,
+				HostID:      1000,
+				Size:        1,
+			},
+		},
+	}
+	uid, err := config.HostRootGID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if uid != 1000 {
+		t.Fatalf("expected gid 1000 with no USERNS but received %d", uid)
+	}
+}