1 files changed, 59 insertions, 0 deletions
diff --git a/middleware/pkg/storage/fs.go b/middleware/pkg/storage/fs.go
new file mode 100644
index 000000000..3ee14b7ed
--- /dev/null
+++ b/middleware/pkg/storage/fs.go
@@ -0,0 +1,59 @@
+package storage
+
+import (
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
+)
+
+// dir wraps an http.Dir that restrict file access to a specific directory tree, see http.Dir's documentation
+// for methods for accessing files.
+type dir http.Dir
+
+// CoreDir is the directory where middleware can store assets, like zone files after a zone transfer
+// or public and private keys or anything else a middleware might need. The convention is to place
+// assets in a subdirectory named after the zone prefixed with "D", to prevent the root zone become a hidden directory.
+//
+// Dexample.org/Kexample.org<something>.key
+//
+// Note that subzone(s) under example.org are places in the own directory under CoreDir:
+//
+// Dexample.org/...
+// Db.example.org/...
+//
+// CoreDir will default to "$HOME/.coredns" on Unix, but it's location can be overriden with the COREDNSPATH
+// environment variable.
+var CoreDir dir = dir(fsPath())
+
+func (d dir) Zone(z string) dir {
+	if z != "." && z[len(z)-2] == '.' {
+		return dir(path.Join(string(d), "D"+z[:len(z)-1]))
+	}
+	return dir(path.Join(string(d), "D"+z))
+}
+
+// fsPath returns the path to the directory where the application may store data.
+// If COREDNSPATH env variable. is set, that value is used. Otherwise, the path is
+// the result of evaluating "$HOME/.coredns".
+func fsPath() string {
+	if corePath := os.Getenv("COREDNSPATH"); corePath != "" {
+		return corePath
+	}
+	return filepath.Join(userHomeDir(), ".coredns")
+}
+
+// userHomeDir returns the user's home directory according to environment variables.
+//
+// Credit: http://stackoverflow.com/a/7922977/1048862
+func userHomeDir() string {
+	if runtime.GOOS == "windows" {
+		home := os.Getenv("HOMEDRIVE") + os.Getenv("HOMEPATH")
+		if home == "" {
+			home = os.Getenv("USERPROFILE")
+		}
+		return home
+	}
+	return os.Getenv("HOME")
+}