FooterLine: Protect from ill-formed message

A raw commit message has some headers and then the actual
message. RawParseUtils.commitMessage returns the start position of the
actual message, or -1 when the message is not raw. FooterLine is not
handling this -1 and throws an IndexOutOfBounds exception.

Consider than msgB can be -1 when looking for the beginning of the
last paragraph.

FooterLine javadoc and parameter talk only about "raw" but previous
code accepted non-raw messages (used mostly in unit tests) so we need
to keep this behavior.

Change-Id: I4b88c507e210fdd200a85b01665c8524ab393b00

2 files changed, 29 insertions, 3 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/FooterLineTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/FooterLineTest.java
index ca6fd4644e..a6808f6351 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/FooterLineTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/FooterLineTest.java
@@ -80,6 +80,24 @@ public class FooterLineTest extends RepositoryTestCase {
 	}
 
 	@Test
+	public void testNoFooters_noRawMsg_SingleLineNoHeaders() {
+		String noRawMsg = "commit message with no header lines\n";
+		List<FooterLine> footers = FooterLine.fromMessage(noRawMsg);
+		assertNotNull(footers);
+		assertEquals(0, footers.size());
+	}
+
+	@Test
+	public void testOneFooter_noRawMsg_MultiParagraphNoHeaders() {
+		String noRawMsg = "subject\n\n"
+			+ "Not: footer\n\n"
+			+ "Footer: value\n";
+		List<FooterLine> footers = FooterLine.fromMessage(noRawMsg);
+		assertNotNull(footers);
+		assertEquals(1, footers.size());
+	}
+
+	@Test
 	public void testSignedOffBy_OneUserNoLF() {
 		String msg = buildMessage("subject\n\nbody of commit\n" + "\n"
 			+ "Signed-off-by: A. U. Thor <a@example.com>");
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FooterLine.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FooterLine.java
index 3968617f8f..d651b63afb 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FooterLine.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FooterLine.java
@@ -87,8 +87,15 @@ public final class FooterLine {
 
 		// Search for the beginning of last paragraph
 		int parStart = parEnd;
-		for (; parStart > msgB && (raw[parStart - 1] != '\n' || raw[parStart - 2] != '\n'); --parStart) {
-			// empty
+		for (; parStart > msgB; --parStart) {
+			if (parStart < 2) {
+				// Too close to beginning: this is not a raw message
+				parStart = 0;
+				break;
+			}
+			if (raw[parStart - 1] == '\n' && raw[parStart - 2] == '\n') {
+				break;
+			}
 		}
 
 		for (int ptr = parStart; ptr < parEnd;) {
@@ -101,7 +108,8 @@ public final class FooterLine {
 			}
 
 			// Skip over the ': *' at the end of the key before the value.
-			int valStart, valEnd;
+			int valStart;
+			int valEnd;
 			for (valStart = keyEnd + 1; valStart < raw.length
 					&& raw[valStart] == ' '; ++valStart) {
 				// empty