PacketLineIn, PacketLineOut: Add support for delim-pkt

Most pkt-lines (data-pkts) have the form

	pkt-len pkt-payload

where pkt-len is a string of 4 hexadecimal digits representing the
size in bytes of the pkt-line.  Since this size includes the size of
the pkt-len, no data-pkt has a length less than 4.

A pkt-line with a length field less than 4 can thus be used for
other purposes.  In Git protocol v1, the only such pkt-line was

	flush-pkt = "0000"

which was used to mark the end of a stream.  Protocol v2 (see
Documentation/technical/protocol-v2.txt in git.git) introduces a
second special pkt-line type:

	delim-pkt = "0001"

used to mark the end of a section within a stream, for example to
separate capabilities from the content of a command.

[jn: split out from a larger patch that made use of this support]

Change-Id: I10e7824fa24ed74c4f45624bd490bba978cf5c34
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jonathan Nieder <jrn@google.com>

2 files changed, 13 insertions, 11 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java
index 13fc68d8c8..982bae8394 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java
@@ -116,17 +116,6 @@ public class PacketLineInTest {
 	}
 
 	@Test
-	public void testReadString_Len0001() {
-		init("0001");
-		try {
-			in.readString();
-			fail("incorrectly accepted invalid packet header");
-		} catch (IOException e) {
-			assertEquals("Invalid packet line header: 0001", e.getMessage());
-		}
-	}
-
-	@Test
 	public void testReadString_Len0002() {
 		init("0002");
 		try {
@@ -164,6 +153,13 @@ public class PacketLineInTest {
 		assertEOF();
 	}
 
+	@Test
+	public void testReadString_Delim() throws IOException {
+		init("0001");
+		assertSame(PacketLineIn.DELIM, in.readString());
+		assertEOF();
+	}
+
 	// readStringNoLF
 
 	@Test
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineOutTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineOutTest.java
index eca54756b1..dd9a0d3bb5 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineOutTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineOutTest.java
@@ -113,6 +113,12 @@ public class PacketLineOutTest {
 		assertEquals(1, flushCnt[0]);
 	}
 
+	@Test
+	public void testWriteDelim() throws IOException {
+		out.writeDelim();
+		assertBuffer("0001");
+	}
+
 	// writePacket
 
 	@Test