[#493] node/config: Implement sections of local object storage

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

cmd/neofs-node/config/engine/shard/metabase/config.go

@@ -0,0 +1,54 @@
+package metabaseconfig
+
+import (
+	"os"
+
+	"github.com/nspcc-dev/neofs-node/cmd/neofs-node/config"
+)
+
+// Config is a wrapper over the config section
+// which provides access to Metabase configurations.
+type Config config.Config
+
+// config defaults
+const (
+	// PermDefault is a default permission bits for metabase file.
+	PermDefault = 0700
+)
+
+// From wraps config section into Config.
+func From(c *config.Config) *Config {
+	return (*Config)(c)
+}
+
+// Path returns value of "path" config parameter.
+//
+// Panics if value is not a non-empty string.
+func (x *Config) Path() string {
+	p := config.String(
+		(*config.Config)(x),
+		"path",
+	)
+
+	if p == "" {
+		panic("metabase path not set")
+	}
+
+	return p
+}
+
+// Perm returns value of "perm" config parameter as a os.FileMode.
+//
+// Returns PermDefault if value is not a positive number.
+func (x *Config) Perm() os.FileMode {
+	p := config.UintSafe(
+		(*config.Config)(x),
+		"perm",
+	)
+
+	if p == 0 {
+		p = PermDefault
+	}
+
+	return os.FileMode(p)
+}