util/pidowner: new package to map from process ID to its user ID

util/pidowner/pidowner.go

@@ -0,0 +1,25 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package pidowner handles lookups from process ID to its owning user.
+package pidowner
+
+import (
+	"errors"
+	"runtime"
+)
+
+var ErrNotImplemented = errors.New("not implemented for GOOS=" + runtime.GOOS)
+
+var ErrProcessNotFound = errors.New("process not found")
+
+// OwnerOfPID returns the user ID that owns the given process ID.
+//
+// The returned user ID is suitable to passing to os/user.LookupId.
+//
+// The returned error will be ErrNotImplemented for operating systems where
+// this isn't supported.
+func OwnerOfPID(pid int) (userID string, err error) {
+	return ownerOfPID(pid)
+}