os/user: add bare-bones implementation of the os/user package

Signed-off-by: Elias Naur <mail@eliasnaur.com>

loader/goroot.go

@@ -244,6 +244,7 @@ func pathsToOverride(goMinor int, needsSyscallPackage bool) map[string]bool {
 		"net/":                  true,
 		"net/http/":             false,
 		"os/":                   true,
+		"os/user/":              false,
 		"reflect/":              false,
 		"runtime/":              false,
 		"sync/":                 true,

src/os/user/user.go

@@ -0,0 +1,41 @@
+// Copyright 2016 The Go 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 user
+
+import "errors"
+
+// User represents a user account.
+type User struct {
+	// Uid is the user ID.
+	// On POSIX systems, this is a decimal number representing the uid.
+	// On Windows, this is a security identifier (SID) in a string format.
+	// On Plan 9, this is the contents of /dev/user.
+	Uid string
+	// Gid is the primary group ID.
+	// On POSIX systems, this is a decimal number representing the gid.
+	// On Windows, this is a SID in a string format.
+	// On Plan 9, this is the contents of /dev/user.
+	Gid string
+	// Username is the login name.
+	Username string
+	// Name is the user's real or display name.
+	// It might be blank.
+	// On POSIX systems, this is the first (or only) entry in the GECOS field
+	// list.
+	// On Windows, this is the user's display name.
+	// On Plan 9, this is the contents of /dev/user.
+	Name string
+	// HomeDir is the path to the user's home directory (if they have one).
+	HomeDir string
+}
+
+// Current returns the current user.
+//
+// The first call will cache the current user information.
+// Subsequent calls will return the cached value and will not reflect
+// changes to the current user.
+func Current() (*User, error) {
+	return nil, errors.New("user: Current not implemented")
+}