{fetch,upload}-pack: sideband v2 fetch response

Currently, a response to a fetch request has sideband support only while
the packfile is being sent, meaning that the server cannot send notices
until the start of the packfile.

Extend sideband support in protocol v2 fetch responses to the whole
response. upload-pack will advertise it if the
uploadpack.allowsidebandall configuration variable is set, and
fetch-pack will automatically request it if advertised.

If the sideband is to be used throughout the whole response, upload-pack
will use it to send errors instead of prefixing a PKT-LINE payload with
"ERR ".

This will be tested in a subsequent patch.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 32 insertions, 11 deletions

diff --git a/pkt-line.c b/pkt-line.c
index 321ff632a5..d4b71d3e82 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -449,7 +449,7 @@ int recv_sideband(const char *me, int in_stream, int out)
 	while (1) {
 		len = packet_read(in_stream, NULL, NULL, buf, LARGE_PACKET_MAX,
 				  0);
-		if (!demultiplex_sideband(me, buf, len, &scratch,
+		if (!demultiplex_sideband(me, buf, len, 0, &scratch,
 					  &sideband_type))
 			continue;
 		switch (sideband_type) {
@@ -475,25 +475,43 @@ void packet_reader_init(struct packet_reader *reader, int fd,
 	reader->buffer = packet_buffer;
 	reader->buffer_size = sizeof(packet_buffer);
 	reader->options = options;
+	reader->me = "git";
 }
 
 enum packet_read_status packet_reader_read(struct packet_reader *reader)
 {
+	struct strbuf scratch = STRBUF_INIT;
+
 	if (reader->line_peeked) {
 		reader->line_peeked = 0;
 		return reader->status;
 	}
 
-	reader->status = packet_read_with_status(reader->fd,
-						 &reader->src_buffer,
-						 &reader->src_len,
-						 reader->buffer,
-						 reader->buffer_size,
-						 &reader->pktlen,
-						 reader->options);
+	/*
+	 * Consume all progress packets until a primary payload packet is
+	 * received
+	 */
+	while (1) {
+		enum sideband_type sideband_type;
+		reader->status = packet_read_with_status(reader->fd,
+							 &reader->src_buffer,
+							 &reader->src_len,
+							 reader->buffer,
+							 reader->buffer_size,
+							 &reader->pktlen,
+							 reader->options);
+		if (!reader->use_sideband)
+			break;
+		if (demultiplex_sideband(reader->me, reader->buffer,
+					 reader->pktlen, 1, &scratch,
+					 &sideband_type))
+			break;
+	}
 
 	if (reader->status == PACKET_READ_NORMAL)
-		reader->line = reader->buffer;
+		/* Skip the sideband designator if sideband is used */
+		reader->line = reader->use_sideband ?
+			reader->buffer + 1 : reader->buffer;
 	else
 		reader->line = NULL;
 
@@ -515,6 +533,7 @@ enum packet_read_status packet_reader_peek(struct packet_reader *reader)
 void packet_writer_init(struct packet_writer *writer, int dest_fd)
 {
 	writer->dest_fd = dest_fd;
+	writer->use_sideband = 0;
 }
 
 void packet_writer_write(struct packet_writer *writer, const char *fmt, ...)
@@ -522,7 +541,8 @@ void packet_writer_write(struct packet_writer *writer, const char *fmt, ...)
 	va_list args;
 
 	va_start(args, fmt);
-	packet_write_fmt_1(writer->dest_fd, 0, "", fmt, args);
+	packet_write_fmt_1(writer->dest_fd, 0,
+			   writer->use_sideband ? "\001" : "", fmt, args);
 	va_end(args);
 }
 
@@ -531,7 +551,8 @@ void packet_writer_error(struct packet_writer *writer, const char *fmt, ...)
 	va_list args;
 
 	va_start(args, fmt);
-	packet_write_fmt_1(writer->dest_fd, 0, "ERR ", fmt, args);
+	packet_write_fmt_1(writer->dest_fd, 0,
+			   writer->use_sideband ? "\003" : "ERR ", fmt, args);
 	va_end(args);
 }