[IO-643] NPE in org.apache.commons.io.FileUtils.contentEquals(File,

File) when only one input is null.

Author: Gary Gregory

src/changes/changes.xml

@@ -171,9 +171,12 @@ The <action> type attribute can be add,update,fix,remove.
       <action issue="IO-641" dev="ggregory" type="add" due-to="Gary Gregory">
         NPE in org.apache.commons.io.IOUtils.contentEquals(Reader, Reader) when only one input is null.
       </action>
-      <action issue="IO-642" dev="ggregory" type="add" due-to="Gary Gregory">
+      <action issue="IO-643" dev="ggregory" type="add" due-to="Gary Gregory">
         NPE in org.apache.commons.io.IOUtils.contentEqualsIgnoreEOL(Reader, Reader) when only one input is null.
       </action>
+      <action issue="IO-643" dev="ggregory" type="add" due-to="Gary Gregory">
+        NPE in org.apache.commons.io.FileUtils.contentEquals(File, File) when only one input is null.
+      </action>
     </release>
 
     <release version="2.6" date="2017-10-15" description="Java 7 required, Java 9 supported.">

src/main/java/org/apache/commons/io/FileUtils.java

@@ -388,6 +388,12 @@ private static void cleanDirectoryOnExit(final File directory) throws IOExceptio
      * @throws IOException in case of an I/O error
      */
     public static boolean contentEquals(final File file1, final File file2) throws IOException {
+        if (file1 == null && file2 == null) {
+            return true;
+        }
+        if (file1 == null ^ file2 == null) {
+            return false;
+        }
         final boolean file1Exists = file1.exists();
         if (file1Exists != file2.exists()) {
             return false;

src/test/java/org/apache/commons/io/FileUtilsTestCase.java

@@ -571,6 +571,9 @@ public void testContentEquals() throws Exception {
         // Non-existent files
         final File file = new File(temporaryFolder, getName());
         final File file2 = new File(temporaryFolder, getName() + "2");
+        assertTrue(FileUtils.contentEquals(null, null));
+        assertFalse(FileUtils.contentEquals(null, file));
+        assertFalse(FileUtils.contentEquals(file, null));
         // both don't  exist
         assertTrue(FileUtils.contentEquals(file, file));
         assertTrue(FileUtils.contentEquals(file, file2));