libpod/container: Replace containerState* with containerPlatformState

This way we don't need to stub in structures for other OSes (e.g. the
Darwin stub in a Linux-only file).  Matthew was concerned about errors
unmarshalling, say, a Linux state object on a Windows box [1], but we
can address that in checks when loading the database [2].

[1]: https://github.com/projectatomic/libpod/pull/1015#discussion_r198649043
[2]: https://github.com/projectatomic/libpod/pull/1015#discussion_r198802956

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #1033
Approved by: mheon

libpod/boltdb_state_internal.go

@@ -3,6 +3,7 @@ package libpod
 import (
 	"encoding/json"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"github.com/boltdb/bolt"
@@ -48,13 +49,14 @@ var (
 // Check if the configuration of the database is compatible with the
 // configuration of the runtime opening it
 // If there is no runtime configuration loaded, load our own
-func checkRuntimeConfig(db *bolt.DB, runtime *Runtime) error {
+func checkRuntimeConfig(db *bolt.DB, rt *Runtime) error {
 	var (
 		staticDir       = []byte("static-dir")
 		tmpDir          = []byte("tmp-dir")
 		runRoot         = []byte("run-root")
 		graphRoot       = []byte("graph-root")
 		graphDriverName = []byte("graph-driver-name")
+		osKey           = []byte("os")
 	)
 
 	err := db.Update(func(tx *bolt.Tx) error {
@@ -63,30 +65,34 @@ func checkRuntimeConfig(db *bolt.DB, runtime *Runtime) error {
 			return err
 		}
 
+		if err := validateDBAgainstConfig(configBkt, "OS", runtime.GOOS, osKey, runtime.GOOS); err != nil {
+			return err
+		}
+
 		if err := validateDBAgainstConfig(configBkt, "static dir",
-			runtime.config.StaticDir, staticDir, ""); err != nil {
+			rt.config.StaticDir, staticDir, ""); err != nil {
 			return err
 		}
 
 		if err := validateDBAgainstConfig(configBkt, "tmp dir",
-			runtime.config.TmpDir, tmpDir, ""); err != nil {
+			rt.config.TmpDir, tmpDir, ""); err != nil {
 			return err
 		}
 
 		if err := validateDBAgainstConfig(configBkt, "run root",
-			runtime.config.StorageConfig.RunRoot, runRoot,
+			rt.config.StorageConfig.RunRoot, runRoot,
 			storage.DefaultStoreOptions.RunRoot); err != nil {
 			return err
 		}
 
 		if err := validateDBAgainstConfig(configBkt, "graph root",
-			runtime.config.StorageConfig.GraphRoot, graphRoot,
+			rt.config.StorageConfig.GraphRoot, graphRoot,
 			storage.DefaultStoreOptions.GraphRoot); err != nil {
 			return err
 		}
 
 		return validateDBAgainstConfig(configBkt, "graph driver name",
-			runtime.config.StorageConfig.GraphDriverName,
+			rt.config.StorageConfig.GraphDriverName,
 			graphDriverName,
 			storage.DefaultStoreOptions.GraphDriverName)
 	})

libpod/container.go

@@ -173,12 +173,8 @@ type containerState struct {
 	// and not delegated to the OCI runtime.
 	ExtensionStageHooks map[string][]spec.Hook `json:"extensionStageHooks,omitempty"`
 
-	// Special container state attributes for Linux
-	containerStateLinux
-	// Special container state attributes for Windows
-	containerStateWindows
-	// Special container state attributes for Darwin
-	containerStateDarwin
+	// containerPlatformState holds platform-specific container state.
+	containerPlatformState
 }
 
 // ExecSession contains information on an active exec session

libpod/container_darwin.go

@@ -1,14 +0,0 @@
-// +build darwin
-
-package libpod
-
-type containerStateDarwin struct {
-}
-
-// containerStateLinux is intentionally left as a blank stub
-type containerStateLinux struct {
-}
-
-// containerStateWindows is intentionally left as a blank stub
-type containerStateWindows struct {
-}

libpod/container_linux.go

@@ -6,18 +6,10 @@ import (
 	"github.com/containernetworking/plugins/pkg/ns"
 )
 
-type containerStateLinux struct {
+type containerPlatformState struct {
 
 	// NetNSPath is the path of the container's network namespace
 	// Will only be set if config.CreateNetNS is true, or the container was
 	// told to join another container's network namespace
 	NetNS ns.NetNS `json:"-"`
 }
-
-// containerStateWindows is intentionally left as a blank stub
-type containerStateWindows struct {
-}
-
-// containerStateDarwin is intentionally left as a blank stub
-type containerStateDarwin struct {
-}

libpod/container_unsupported.go

@@ -0,0 +1,5 @@
+// +build !linux
+
+package libpod
+
+type containerPlatformState struct{}

libpod/container_windows.go

@@ -1,14 +0,0 @@
-// +build windows
-
-package libpod
-
-type containerStateWindows struct {
-}
-
-// containerStateLinux is intentionally left as a blank stub
-type containerStateLinux struct {
-}
-
-// containerStateDarwin is intentionally left as a blank stub
-type containerStateDarwin struct {
-}