From af4e690837bbd939c38bfafb9e27d7ad424dce61 Mon Sep 17 00:00:00 2001
From: Thomas Stromberg <tstromberg@google.com>
Date: Wed, 11 Dec 2019 09:14:20 -0800
Subject: [PATCH] Use sha1 for a larger hash, truncated to 40 chars

---
 pkg/util/lock/lock.go      | 13 ++++++-------
 pkg/util/lock/lock_test.go |  4 ++--
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/pkg/util/lock/lock.go b/pkg/util/lock/lock.go
index d5c945b9d8..6c5eee6ac8 100644
--- a/pkg/util/lock/lock.go
+++ b/pkg/util/lock/lock.go
@@ -17,12 +17,11 @@ limitations under the License.
 package lock
 
 import (
-	"crypto/md5"
+	"crypto/sha1"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"os/user"
-	"regexp"
 	"time"
 
 	"github.com/golang/glog"
@@ -32,8 +31,6 @@ import (
 )
 
 var (
-	// nonString is characters to strip from lock names
-	nonString = regexp.MustCompile(`[\W_]+`)
 	// forceID is a user id for consistent testing
 	forceID = ""
 )
@@ -64,9 +61,10 @@ func UserMutexSpec(path string) mutex.Spec {
 			id = u.Uid
 		}
 	}
-
+	name := getMutexNameForPath(fmt.Sprintf("%s-%s", path, id))
+	glog.Infof("mutex name for %s: %s", path, name)
 	s := mutex.Spec{
-		Name:  getMutexNameForPath(fmt.Sprintf("%s-%s", path, id)),
+		Name:  name,
 		Clock: clock.WallClock,
 		// Poll the lock twice a second
 		Delay: 500 * time.Millisecond,
@@ -78,5 +76,6 @@ func UserMutexSpec(path string) mutex.Spec {
 
 func getMutexNameForPath(path string) string {
 	// juju requires that names match ^[a-zA-Z][a-zA-Z0-9-]*$", and be under 40 chars long.
-	return fmt.Sprintf("m%x", md5.Sum([]byte(path)))
+	name := fmt.Sprintf("mk%x", sha1.Sum([]byte(path)))
+	return name[0:40]
 }
diff --git a/pkg/util/lock/lock_test.go b/pkg/util/lock/lock_test.go
index d7d7a22fe9..43656fa943 100644
--- a/pkg/util/lock/lock_test.go
+++ b/pkg/util/lock/lock_test.go
@@ -62,8 +62,8 @@ func TestUserMutexSpec(t *testing.T) {
 	for _, tc := range tests {
 		t.Run(tc.description, func(t *testing.T) {
 			got := UserMutexSpec(tc.path)
-			if len(got.Name) > 40 {
-				t.Errorf("%s mutex name is too long", got.Name)
+			if len(got.Name) != 40 {
+				t.Errorf("%s is not 40 chars long", got.Name)
 			}
 		})
 	}