IO-727: fix directoryContains() handling files with the same prefix

Author: trgpa

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

@@ -518,7 +518,7 @@ public static String concat(final String basePath, final String fullFileNameToAd
     /**
      * Determines whether the {@code parent} directory contains the {@code child} element (a file or directory).
      * <p>
-     * The files names are expected to be normalized.
+     * The files names are expected to be canonical.
      * </p>
      *
      * Edge cases:
@@ -541,15 +541,21 @@ public static boolean directoryContains(final String canonicalParent, final Stri
             throws IOException {
         Objects.requireNonNull(canonicalParent, "canonicalParent");
 
-        if (canonicalChild == null) {
+        if (canonicalChild == null || canonicalChild.isEmpty() || canonicalParent.isEmpty()) {
             return false;
         }
 
         if (IOCase.SYSTEM.checkEquals(canonicalParent, canonicalChild)) {
             return false;
         }
 
-        return IOCase.SYSTEM.checkStartsWith(canonicalChild, canonicalParent);
+        final char separator = canonicalParent.charAt(0) == UNIX_SEPARATOR ? UNIX_SEPARATOR : WINDOWS_SEPARATOR;
+        final String parentWithEndSeparator =
+                canonicalParent.charAt(canonicalParent.length() - 1) == separator
+                        ? canonicalParent
+                        : canonicalParent + separator;
+
+        return IOCase.SYSTEM.checkStartsWith(canonicalChild, parentWithEndSeparator);
     }
 
     /**

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

@@ -134,9 +134,16 @@ public void testSameFile() throws IOException {
     }
 
     @Test
-    public void testIO466() throws IOException {
-            final File fooFile = new File(directory1.getParent(), "directory1.txt");
-            assertFalse(FileUtils.directoryContains(directory1, fooFile));
+    public void testFileHavingSamePrefixBug() throws IOException {
+        final File foo = new File(top, "foo");
+        final File foobar = new File(top, "foobar");
+        final File fooTxt = new File(top, "foo.txt");
+        foo.mkdir();
+        foobar.mkdir();
+        FileUtils.touch(fooTxt);
+
+        assertFalse(FileUtils.directoryContains(foo, foobar));
+        assertFalse(FileUtils.directoryContains(foo, fooTxt));
     }
 
     @Test

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

@@ -1193,4 +1193,21 @@ public void testIsExtensionCollection() {
         assertFalse(FilenameUtils.isExtension("a.b\\file.txt", new ArrayList<>(Arrays.asList("TXT"))));
         assertFalse(FilenameUtils.isExtension("a.b\\file.txt", new ArrayList<>(Arrays.asList("TXT", "RTF"))));
     }
+
+    //-----------------------------------------------------------------------
+    @Test
+    public void testDirectoryContains() throws IOException {
+        assertTrue(FilenameUtils.directoryContains("/foo", "/foo/bar"));
+        assertTrue(FilenameUtils.directoryContains("/foo/", "/foo/bar"));
+        assertTrue(FilenameUtils.directoryContains("C:\\foo", "C:\\foo\\bar"));
+        assertTrue(FilenameUtils.directoryContains("C:\\foo\\", "C:\\foo\\bar"));
+
+        assertFalse(FilenameUtils.directoryContains("/foo", "/foo"));
+        assertFalse(FilenameUtils.directoryContains("/foo", "/foobar"));
+        assertFalse(FilenameUtils.directoryContains("C:\\foo", "C:\\foobar"));
+        assertFalse(FilenameUtils.directoryContains("/foo", null));
+        assertFalse(FilenameUtils.directoryContains("", ""));
+        assertFalse(FilenameUtils.directoryContains("", "/foo"));
+        assertFalse(FilenameUtils.directoryContains("/foo", ""));
+    }
 }