add license header for hdfs_kerberos.go

object/hdfs_kerberos.go

+// Copyright (c) 2014 Colin Marc (colinmarc@gmail.com)
+// borrowed from https://github.com/colinmarc/hdfs/blob/master/cmd/hdfs/kerberos.go
+
+package object
+
+import (
+	"fmt"
+	"os"
+	"os/user"
+	"strings"
+
+	krb "github.com/jcmturner/gokrb5/v8/client"
+	"github.com/jcmturner/gokrb5/v8/config"
+	"github.com/jcmturner/gokrb5/v8/credentials"
+)
+
+func getKerberosClient() (*krb.Client, error) {
+	configPath := os.Getenv("KRB5_CONFIG")
+	if configPath == "" {
+		configPath = "/etc/krb5.conf"
+	}
+
+	cfg, err := config.Load(configPath)
+	if err != nil {
+		return nil, err
+	}
+
+	// Determine the ccache location from the environment, falling back to the
+	// default location.
+	ccachePath := os.Getenv("KRB5CCNAME")
+	if strings.Contains(ccachePath, ":") {
+		if strings.HasPrefix(ccachePath, "FILE:") {
+			ccachePath = strings.SplitN(ccachePath, ":", 2)[1]
+		} else {
+			return nil, fmt.Errorf("unusable ccache: %s", ccachePath)
+		}
+	} else if ccachePath == "" {
+		u, err := user.Current()
+		if err != nil {
+			return nil, err
+		}
+
+		ccachePath = fmt.Sprintf("/tmp/krb5cc_%s", u.Uid)
+	}
+
+	ccache, err := credentials.LoadCCache(ccachePath)
+	if err != nil {
+		return nil, err
+	}
+
+	client, err := krb.NewFromCCache(ccache, cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	return client, nil
+}