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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>
stable-5.0
Jonathan Tan 7 years ago committed by Jonathan Nieder
parent
commit
75b0703692
  1. 18
      org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java
  2. 6
      org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineOutTest.java
  3. 14
      org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java
  4. 14
      org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java

18
org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PacketLineInTest.java

@ -115,17 +115,6 @@ 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");
@ -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

6
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

14
org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java

@ -74,6 +74,13 @@ public class PacketLineIn {
/** Magic return from {@link #readString()} when a flush packet is found. */
public static final String END = new StringBuilder(0).toString(); /* must not string pool */
/**
* Magic return from {@link #readString()} when a delim packet is found.
*
* @since 5.0
*/
public static final String DELIM = new StringBuilder(0).toString(); /* must not string pool */
static enum AckNackResult {
/** NAK */
NAK,
@ -147,6 +154,7 @@ public class PacketLineIn {
* use {@link #readStringRaw()} instead.
*
* @return the string. {@link #END} if the string was the magic flush
* packet, {@link #DELIM} if the string was the magic DELIM
* packet.
* @throws java.io.IOException
* the stream cannot be read.
@ -157,6 +165,10 @@ public class PacketLineIn {
log.debug("git< 0000"); //$NON-NLS-1$
return END;
}
if (len == 1) {
log.debug("git< 0001"); //$NON-NLS-1$
return DELIM;
}
len -= 4; // length header (4 bytes)
if (len == 0) {
@ -232,6 +244,8 @@ public class PacketLineIn {
if (len == 0) {
return 0;
} else if (len == 1) {
return 1;
} else if (len < 4) {
throw invalidHeader();
}

14
org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java

@ -146,6 +146,20 @@ public class PacketLineOut {
}
}
/**
* Write a packet delim marker (0001).
*
* @throws java.io.IOException
* the marker could not be written, the stream is corrupted
* as the marker may have been only partially written.
* @since 5.0
*/
public void writeDelim() throws IOException {
formatLength(1);
out.write(lenbuffer, 0, 4);
log.debug("git> 0001"); //$NON-NLS-1$
}
/**
* Write a packet end marker, sometimes referred to as a flush command.
* <p>

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