[FIXED JENKINS-18351] file descriptor leak while fingerprinting

changelog.html

@@ -61,6 +61,9 @@ Upcoming changes</a>
   <li class=bug>
     “Projects tied to slave” shows unrelated Maven module jobs.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17451">issue 17451</a>)
+  <li class=bug>
+    Fixed file descriptor leak in fingerprint computation.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-18351">issue 18351</a>)
   <li class=rfe>
     Added a new extension point to monitor the flow of stuff in the queue.
   <li class=rfe>

core/src/main/java/hudson/FilePath.java

@@ -1664,7 +1664,12 @@ public final class FilePath implements Serializable {
         return act(new FileCallable<String>() {
             private static final long serialVersionUID = 1L;
             public String invoke(File f, VirtualChannel channel) throws IOException {
-                return Util.getDigestOf(new BufferedInputStream(new FileInputStream(f)));
+                BufferedInputStream source = new BufferedInputStream(new FileInputStream(f));
+                try {
+                    return Util.getDigestOf(source);
+                } finally {
+                    source.close();
+                }
             }
         });
     }