NIFI-16000: Allow spaces in FileUtils.getSanitizedFilename

nifi-commons/nifi-utils/src/main/java/org/apache/nifi/util/file/FileUtils.java

@@ -581,15 +581,18 @@ public static long getContainerUsableSpace(final Path path) {
 
     // The invalid character list is derived from this Stackoverflow page.
     // https://stackoverflow.com/questions/1155107/is-there-a-cross-platform-java-method-to-remove-filename-special-chars
+    // The space character (32) is intentionally omitted: spaces are legal on every major file system, so they are
+    // preserved rather than replaced.
     private static final int[] INVALID_CHARS = {34, 60, 62, 124, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
-            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 58, 42, 63, 92, 47, 32};
+            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 58, 42, 63, 92, 47};
 
     static {
         Arrays.sort(INVALID_CHARS);
     }
 
     /**
      * Replaces invalid characters for a file system name within a given filename string to underscore '_'.
+     * Spaces are permitted and preserved.
      * Be careful not to pass a file path as this method replaces path delimiter characters (i.e forward/back slashes).
      * @param filename The filename to clean
      * @return sanitized filename
@@ -602,10 +605,10 @@ public static String getSanitizedFilename(String filename) {
             return "";
         }
 
-        int codePointCount = filename.codePointCount(0, filename.length());
+        final int codePointCount = filename.codePointCount(0, filename.length());
         final StringBuilder cleanName = new StringBuilder();
         for (int i = 0; i < codePointCount; i++) {
-            int c = filename.codePointAt(i);
+            final int c = filename.codePointAt(i);
             if (Arrays.binarySearch(INVALID_CHARS, c) < 0) {
                 cleanName.appendCodePoint(c);
             } else {

nifi-commons/nifi-utils/src/test/java/org/apache/nifi/util/file/TestFileUtils.java

@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.util.file;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class TestFileUtils {
+
+    @Test
+    public void testGetSanitizedFilenameNullAndEmpty() {
+        assertNull(FileUtils.getSanitizedFilename(null));
+        assertEquals("", FileUtils.getSanitizedFilename(""));
+    }
+
+    @Test
+    public void testGetSanitizedFilenameReplacesInvalidCharacters() {
+        assertEquals("a_b_c", FileUtils.getSanitizedFilename("a/b\\c"));
+        assertEquals("name_", FileUtils.getSanitizedFilename("name:"));
+        assertEquals("a_b", FileUtils.getSanitizedFilename("a\tb"));
+        assertEquals("_", FileUtils.getSanitizedFilename("*"));
+    }
+
+    @Test
+    public void testGetSanitizedFilenamePreservesSpaces() {
+        assertEquals("driver (1).jar", FileUtils.getSanitizedFilename("driver (1).jar"));
+        assertEquals("my report.txt", FileUtils.getSanitizedFilename("my report.txt"));
+        assertEquals("driver   (1).jar", FileUtils.getSanitizedFilename("driver   (1).jar"));
+        assertEquals(" driver (1).jar ", FileUtils.getSanitizedFilename(" driver (1).jar "));
+    }
+
+    @Test
+    public void testGetSanitizedFilenamePreservesDots() {
+        assertEquals("report...", FileUtils.getSanitizedFilename("report..."));
+        assertEquals(".env", FileUtils.getSanitizedFilename(".env"));
+    }
+}