fix: ignore . path segment

src/main/java/org/apache/commons/codec/digest/GitIdentifiers.java

@@ -191,11 +191,13 @@ private interface BlobIdSupplier {
             byte[] get() throws IOException;
         }
 
-        private static void checkPathComponent(String name) {
-            if (".".equals(name) || "..".equals(name)) {
+        private static String requireNoParentTraversal(String name) {
+            if ("..".equals(name)) {
                 throw new IllegalArgumentException("Path component not allowed: " + name);
             }
+            return name;
         }
+
         private final Map<String, TreeIdBuilder> dirEntries = new HashMap<>();
         private final Map<String, DirectoryEntry> fileEntries = new HashMap<>();
         private final MessageDigest messageDigest;
@@ -209,16 +211,16 @@ private TreeIdBuilder(final MessageDigest messageDigest) {
          *
          * @param name The relative path of the subdirectory in normalized form (may contain {@code '/'}).
          * @return The {@link TreeIdBuilder} for the subdirectory.
-         * @throws IllegalArgumentException If any path component is {@code "."} or {@code ".."}.
+         * @throws IllegalArgumentException If any path component is {@code ".."}.
          */
         public TreeIdBuilder addDirectory(final String name) {
             TreeIdBuilder current = this;
             for (final String component : name.split("/", -1)) {
-                if (component.isEmpty()) {
+                // Noop segments
+                if (component.isEmpty() || ".".equals(component)) {
                     continue;
                 }
-                checkPathComponent(component);
-                current = current.dirEntries.computeIfAbsent(component, k -> new TreeIdBuilder(messageDigest));
+                current = current.dirEntries.computeIfAbsent(requireNoParentTraversal(component), k -> new TreeIdBuilder(messageDigest));
             }
             return current;
         }
@@ -235,17 +237,16 @@ public TreeIdBuilder addDirectory(final String name) {
          * @param dataSize The exact number of bytes in {@code data}.
          * @param data     The file content.
          * @throws IOException If the stream cannot be read.
-         * @throws IllegalArgumentException If any path component is {@code "."} or {@code ".."}.
+         * @throws IllegalArgumentException If any path component is {@code ".."}.
          */
         public void addFile(final FileMode mode, final String name, final long dataSize, final InputStream data) throws IOException {
             addFile(mode, name, () -> blobId(messageDigest, dataSize, data));
         }
 
         private void addFile(final FileMode mode, final String name, final BlobIdSupplier blobId) throws IOException {
-            final int slash = name.indexOf('/');
+            final int slash = name.lastIndexOf('/');
             if (slash < 0) {
-                checkPathComponent(name);
-                fileEntries.put(name, new DirectoryEntry(name, mode, blobId.get()));
+                fileEntries.put(name, new DirectoryEntry(requireNoParentTraversal(name), mode, blobId.get()));
             } else {
                 addDirectory(name.substring(0, slash)).addFile(mode, name.substring(slash + 1), blobId);
             }
@@ -260,7 +261,7 @@ private void addFile(final FileMode mode, final String name, final BlobIdSupplie
          * @param name The relative path of the entry in normalized form(may contain {@code '/'}).
          * @param data The file content.
          * @throws IOException If an I/O error occurs.
-         * @throws IllegalArgumentException If any path component is {@code "."} or {@code ".."}.
+         * @throws IllegalArgumentException If any path component is {@code ".."}.
          */
         public void addFile(final FileMode mode, final String name, final byte[] data) throws IOException {
             addFile(mode, name, () -> blobId(messageDigest, data));
@@ -274,7 +275,7 @@ public void addFile(final FileMode mode, final String name, final byte[] data) t
          * @param name The relative path of the entry in normalized form(may contain {@code '/'}).
          * @param target The target of the symbolic link.
          * @throws IOException If an I/O error occurs.
-         * @throws IllegalArgumentException If any path component is {@code "."} or {@code ".."}.
+         * @throws IllegalArgumentException If any path component is {@code ".."}.
          */
         public void addSymbolicLink(final String name, final String target) throws IOException {
             addFile(FileMode.SYMBOLIC_LINK, name, target.getBytes(StandardCharsets.UTF_8));

src/test/java/org/apache/commons/codec/digest/GitIdentifiersTest.java

@@ -204,46 +204,19 @@ void testTreeIdBuilderAddFileInputStream() throws Exception {
     }
 
     @Test
-    void testTreeIdBuilderEmptyPathSegments() throws Exception {
-        final MessageDigest md = DigestUtils.getSha1Digest();
-        final byte[] content = "hello\n".getBytes(StandardCharsets.UTF_8);
-
-        // Canonical form
-        final GitIdentifiers.TreeIdBuilder canonical = GitIdentifiers.treeIdBuilder(md);
-        canonical.addFile(GitIdentifiers.FileMode.REGULAR, "subdir/file.txt", content);
-        final byte[] expected = canonical.build();
-
-        // Leading slash
-        final GitIdentifiers.TreeIdBuilder withLeading = GitIdentifiers.treeIdBuilder(md);
-        withLeading.addFile(GitIdentifiers.FileMode.REGULAR, "/subdir/file.txt", content);
-        assertArrayEquals(expected, withLeading.build());
-
-        // Consecutive slashes
-        final GitIdentifiers.TreeIdBuilder withDouble = GitIdentifiers.treeIdBuilder(md);
-        withDouble.addFile(GitIdentifiers.FileMode.REGULAR, "subdir//file.txt", content);
-        assertArrayEquals(expected, withDouble.build());
-
-        // addDirectory with leading/trailing slashes
-        final GitIdentifiers.TreeIdBuilder viaDirectory = GitIdentifiers.treeIdBuilder(md);
-        viaDirectory.addDirectory("/subdir/").addFile(GitIdentifiers.FileMode.REGULAR, "file.txt", content);
-        assertArrayEquals(expected, viaDirectory.build());
-    }
-
-    @ParameterizedTest
-    @ValueSource(strings = {".", ".."})
-    void testTreeIdBuilderInvalidPathSegments(final String segment) {
+    void testTreeIdBuilderInvalidPathSegments() {
         final MessageDigest md = DigestUtils.getSha1Digest();
         final byte[] data = new byte[0];
         // Sole path component
         assertThrows(IllegalArgumentException.class,
-                () -> GitIdentifiers.treeIdBuilder(md).addFile(GitIdentifiers.FileMode.REGULAR, segment, data));
+                () -> GitIdentifiers.treeIdBuilder(md).addFile(GitIdentifiers.FileMode.REGULAR, "..", data));
         assertThrows(IllegalArgumentException.class,
-                () -> GitIdentifiers.treeIdBuilder(md).addDirectory(segment));
+                () -> GitIdentifiers.treeIdBuilder(md).addDirectory(".."));
         // Embedded in a longer path
         assertThrows(IllegalArgumentException.class,
-                () -> GitIdentifiers.treeIdBuilder(md).addFile(GitIdentifiers.FileMode.REGULAR, "subdir/" + segment + "/file.txt", data));
+                () -> GitIdentifiers.treeIdBuilder(md).addFile(GitIdentifiers.FileMode.REGULAR, "subdir/../file.txt", data));
         assertThrows(IllegalArgumentException.class,
-                () -> GitIdentifiers.treeIdBuilder(md).addDirectory("subdir/" + segment));
+                () -> GitIdentifiers.treeIdBuilder(md).addDirectory("subdir/.."));
     }
 
     @Test
@@ -260,6 +233,33 @@ void testTreeIdBuilderNestedFileEquivalentToDirectoryAndFile() throws Exception
         assertArrayEquals(direct.build(), indirect.build());
     }
 
+    @ParameterizedTest
+    @ValueSource(strings = {"", "."})
+    void testTreeIdBuilderNoopPathSegments(String segment) throws Exception {
+        final MessageDigest md = DigestUtils.getSha1Digest();
+        final byte[] content = "hello\n".getBytes(StandardCharsets.UTF_8);
+
+        // Canonical form
+        final GitIdentifiers.TreeIdBuilder canonical = GitIdentifiers.treeIdBuilder(md);
+        canonical.addFile(GitIdentifiers.FileMode.REGULAR, "subdir/file.txt", content);
+        final byte[] expected = canonical.build();
+
+        // Leading segment
+        final GitIdentifiers.TreeIdBuilder withLeading = GitIdentifiers.treeIdBuilder(md);
+        withLeading.addFile(GitIdentifiers.FileMode.REGULAR, segment + "/subdir/file.txt", content);
+        assertArrayEquals(expected, withLeading.build());
+
+        // Intermediate segment
+        final GitIdentifiers.TreeIdBuilder withIntermediate = GitIdentifiers.treeIdBuilder(md);
+        withIntermediate.addFile(GitIdentifiers.FileMode.REGULAR, "subdir/" + segment + "/file.txt", content);
+        assertArrayEquals(expected, withIntermediate.build());
+
+        // addDirectory with leading/trailing segments
+        final GitIdentifiers.TreeIdBuilder viaDirectory = GitIdentifiers.treeIdBuilder(md);
+        viaDirectory.addDirectory(segment + "/subdir/" + segment).addFile(GitIdentifiers.FileMode.REGULAR, "file.txt", content);
+        assertArrayEquals(expected, viaDirectory.build());
+    }
+
     @Test
     void testTreeIdPath() throws Exception {
         assertArrayEquals(Hex.decodeHex("e4b21f6d78ceba6eb7c211ac15e3337ec4614e8a"),