From 3a0a3228ec9a7ef6d5ff766e0ee0737e547f92a4 Mon Sep 17 00:00:00 2001
From: Stephen Compall <stephen.compall@daml.com>
Date: Fri, 31 Jul 2020 10:59:39 -0400
Subject: [PATCH] fix null pointer in PortLock#lock (#6941)

java.lang.NullPointerException:
  at com.daml.ports.PortLock$Locked.unlock(PortLock.scala:55)
  at com.daml.ports.PortLock$.lock(PortLock.scala:41)
  at com.daml.ports.LockedFreePort$.find(LockedFreePort.scala:15)
  at com.daml.lf.engine.trigger.TriggerServiceFixture$.$anonfun$withTriggerService$1(TriggerServiceFixture.scala:65)

CHANGELOG_BEGIN
CHANGELOG_END
---
 .../scala/com/digitalasset/ports/PortLock.scala   | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/libs-scala/ports/src/main/scala/com/digitalasset/ports/PortLock.scala b/libs-scala/ports/src/main/scala/com/digitalasset/ports/PortLock.scala
index 57743a1cb0..8ef8129921 100644
--- a/libs-scala/ports/src/main/scala/com/digitalasset/ports/PortLock.scala
+++ b/libs-scala/ports/src/main/scala/com/digitalasset/ports/PortLock.scala
@@ -33,14 +33,13 @@ object PortLock {
     val file = new RandomAccessFile(portLockFile.toFile, "rw")
     val channel = file.getChannel
     try {
-      val lock = channel.tryLock()
-      val locked = new Locked(port, lock, channel, file)
-      if (lock != null) {
-        Right(locked)
-      } else {
-        locked.unlock()
-        Left(FailedToLock(port))
-      }
+      Option(channel.tryLock())
+        .map(lock => new Locked(port, lock, channel, file))
+        .toRight {
+          channel.close()
+          file.close()
+          FailedToLock(port)
+        }
     } catch {
       case _: OverlappingFileLockException =>
         channel.close()