wumpz · Oct 10, 2026 · Oct 10, 2026
diff --git a/java-diff-utils/src/main/java/com/github/difflib/unifieddiff/UnifiedDiffReader.java b/java-diff-utils/src/main/java/com/github/difflib/unifieddiff/UnifiedDiffReader.java
@@ -279,7 +279,9 @@ private void initFileIfNecessary() {
 		}
 
 		private void processDiff(MatchResult match, String line) {
-				// initFileIfNecessary();
+				if (actualFile.getDiffCommand() != null) {
+						initFileIfNecessary();
+				}
 				LOG.log(Level.FINE, "start {0}", line);
 				String[] fromTo = parseFileNames(READER.lastLine());
 				actualFile.setFromFile(fromTo[0]);

diff --git a/...utils/src/test/java/com/github/difflib/unifieddiff/UnifiedDiffReaderFileBoundaryTest.java b/...utils/src/test/java/com/github/difflib/unifieddiff/UnifiedDiffReaderFileBoundaryTest.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright 2026 java-diff-utils.
+ *
+ * Licensed 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 com.github.difflib.unifieddiff;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.difflib.patch.PatchFailedException;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Collections;
+import org.junit.jupiter.api.Test;
+
+public class UnifiedDiffReaderFileBoundaryTest {
+
+		@Test
+		public void testParseHeaderOnlyFilesBeforeTextChange() throws IOException, PatchFailedException {
+				UnifiedDiff diff = UnifiedDiffReader.parseUnifiedDiff(getClass().getResourceAsStream("header_only_files.diff"));
+
+				assertThat(diff.getFiles()).hasSize(5);
+				UnifiedDiffFile binary = diff.getFiles().get(0);
+				assertThat(binary.getFromFile()).isEqualTo("a-image.bin");
+				assertThat(binary.getToFile()).isEqualTo("a-image.bin");
+				assertThat(binary.getBinaryEdited()).isEqualTo("a-image.bin");
+				assertThat(binary.getPatch().getDeltas()).isEmpty();
+
+				UnifiedDiffFile empty = diff.getFiles().get(1);
+				assertThat(empty.getToFile()).isEqualTo("b-empty.txt");
+				assertThat(empty.getNewFileMode()).isEqualTo("100644");
+				assertThat(empty.getBinaryEdited()).isNull();
+				assertThat(empty.getPatch().getDeltas()).isEmpty();
+
+				UnifiedDiffFile mode = diff.getFiles().get(2);
+				assertThat(mode.getFromFile()).isEqualTo("c-script.sh");
+				assertThat(mode.getOldMode()).isEqualTo("100644");
+				assertThat(mode.getNewMode()).isEqualTo("100755");
+				assertThat(mode.getNewFileMode()).isNull();
+				assertThat(mode.getPatch().getDeltas()).isEmpty();
+
+				UnifiedDiffFile rename = diff.getFiles().get(3);
+				assertThat(rename.getFromFile()).isEqualTo("d-old.txt");
+				assertThat(rename.getToFile()).isEqualTo("e-renamed.txt");
+				assertThat(rename.getSimilarityIndex()).isEqualTo(100);
+				assertThat(rename.getRenameFrom()).isEqualTo("d-old.txt");
+				assertThat(rename.getRenameTo()).isEqualTo("e-renamed.txt");
+				assertThat(rename.getOldMode()).isNull();
+				assertThat(rename.getPatch().getDeltas()).isEmpty();
+
+				UnifiedDiffFile text = diff.getFiles().get(4);
+				assertThat(text.getFromFile()).isEqualTo("z-text.txt");
+				assertThat(text.getToFile()).isEqualTo("z-text.txt");
+				assertThat(text.getBinaryEdited()).isNull();
+				assertThat(text.getNewFileMode()).isNull();
+				assertThat(text.getNewMode()).isNull();
+				assertThat(text.getRenameFrom()).isNull();
+				assertThat(text.getPatch().applyTo(Collections.singletonList("old"))).containsExactly("new");
+		}
+
+		@Test
+		public void testParseConsecutiveHeaderOnlyFilesAtEndOfDiff() throws IOException {
+				String text = "diff --git a/first.sh b/first.sh\n"
+								+ "old mode 100644\nnew mode 100755\n"
+								+ "diff --git a/second.sh b/second.sh\n"
+								+ "old mode 100755\nnew mode 100644\n";
+				UnifiedDiff diff =
+								UnifiedDiffReader.parseUnifiedDiff(new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8)));
+
+				assertThat(diff.getFiles()).hasSize(2);
+				assertThat(diff.getFiles().get(0).getFromFile()).isEqualTo("first.sh");
+				assertThat(diff.getFiles().get(0).getNewMode()).isEqualTo("100755");
+				assertThat(diff.getFiles().get(1).getFromFile()).isEqualTo("second.sh");
+				assertThat(diff.getFiles().get(1).getNewMode()).isEqualTo("100644");
+				assertThat(diff.getFiles())
+								.allSatisfy(file -> assertThat(file.getPatch().getDeltas()).isEmpty());
+		}
+
+		@Test
+		public void testParseTextChangeBeforeHeaderOnlyAndBinaryFiles() throws IOException, PatchFailedException {
+				String text = "diff --git a/text.txt b/text.txt\n"
+								+ "--- a/text.txt\n+++ b/text.txt\n@@ -1 +1 @@\n-old\n+new\n"
+								+ "diff --git a/script.sh b/script.sh\n"
+								+ "old mode 100644\nnew mode 100755\n"
+								+ "diff --git a/image.bin b/image.bin\n"
+								+ "Binary files a/image.bin and b/image.bin differ\n";
+				UnifiedDiff diff =
+								UnifiedDiffReader.parseUnifiedDiff(new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8)));
+
+				assertThat(diff.getFiles()).hasSize(3);
+				UnifiedDiffFile changed = diff.getFiles().get(0);
+				assertThat(changed.getFromFile()).isEqualTo("text.txt");
+				assertThat(changed.getNewMode()).isNull();
+				assertThat(changed.getBinaryEdited()).isNull();
+				assertThat(changed.getPatch().applyTo(Collections.singletonList("old"))).containsExactly("new");
+				UnifiedDiffFile mode = diff.getFiles().get(1);
+				assertThat(mode.getFromFile()).isEqualTo("script.sh");
+				assertThat(mode.getNewMode()).isEqualTo("100755");
+				assertThat(mode.getBinaryEdited()).isNull();
+				assertThat(mode.getPatch().getDeltas()).isEmpty();
+				UnifiedDiffFile binary = diff.getFiles().get(2);
+				assertThat(binary.getFromFile()).isEqualTo("image.bin");
+				assertThat(binary.getBinaryEdited()).isEqualTo("image.bin");
+				assertThat(binary.getNewMode()).isNull();
+				assertThat(binary.getPatch().getDeltas()).isEmpty();
+		}
+}
diff --git a/java-diff-utils/src/test/resources/com/github/difflib/unifieddiff/header_only_files.diff b/java-diff-utils/src/test/resources/com/github/difflib/unifieddiff/header_only_files.diff
@@ -0,0 +1,20 @@
+diff --git a/a-image.bin b/a-image.bin
+index eaf36c1..f75c32a 100644
+Binary files a/a-image.bin and b/a-image.bin differ
+diff --git a/b-empty.txt b/b-empty.txt
+new file mode 100644
+index 0000000..e69de29
+diff --git a/c-script.sh b/c-script.sh
+old mode 100644
+new mode 100755
+diff --git a/d-old.txt b/e-renamed.txt
+similarity index 100%
+rename from d-old.txt
+rename to e-renamed.txt
+diff --git a/z-text.txt b/z-text.txt
+index 3367afd..3e75765 100644
+--- a/z-text.txt
++++ b/z-text.txt
+@@ -1 +1 @@
+-old
++new