1 files changed, 78 insertions, 0 deletions
diff --git a/sideband.c b/sideband.c
new file mode 100644
index 0000000..277fa3c
--- /dev/null
+++ b/sideband.c
@@ -0,0 +1,78 @@
+#include "pkt-line.h"
+#include "sideband.h"
+
+/*
+ * Receive multiplexed output stream over git native protocol.
+ * in_stream is the input stream from the remote, which carries data
+ * in pkt_line format with band designator.  Demultiplex it into out
+ * and err and return error appropriately.  Band #1 carries the
+ * primary payload.  Things coming over band #2 is not necessarily
+ * error; they are usually informative message on the standard error
+ * stream, aka "verbose").  A message over band #3 is a signal that
+ * the remote died unexpectedly.  A flush() concludes the stream.
+ */
+int recv_sideband(const char *me, int in_stream, int out, int err)
+{
+	char buf[7 + LARGE_PACKET_MAX + 1];
+	strcpy(buf, "remote:");
+	while (1) {
+		int band, len;
+		len	= packet_read_line(in_stream, buf+7, LARGE_PACKET_MAX);
+		if (len == 0)
+			break;
+		if (len < 1) {
+			len = sprintf(buf, "%s: protocol error: no band designator\n", me);
+			safe_write(err, buf, len);
+			return SIDEBAND_PROTOCOL_ERROR;
+		}
+		band = buf[7] & 0xff;
+		len--;
+		switch (band) {
+		case 3:
+			buf[7] = ' ';
+			buf[8+len] = '\n';
+			safe_write(err, buf, 8+len+1);
+			return SIDEBAND_REMOTE_ERROR;
+		case 2:
+			buf[7] = ' ';
+			safe_write(err, buf, 8+len);
+			continue;
+		case 1:
+			safe_write(out, buf+8, len);
+			continue;
+		default:
+			len = sprintf(buf,
+				      "%s: protocol error: bad band #%d\n",
+				      me, band);
+			safe_write(err, buf, len);
+			return SIDEBAND_PROTOCOL_ERROR;
+		}
+	}
+	return 0;
+}
+
+/*
+ * fd is connected to the remote side; send the sideband data
+ * over multiplexed packet stream.
+ */
+ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max)
+{
+	ssize_t ssz = sz;
+	const char *p = data;
+
+	while (sz) {
+		unsigned n;
+		char hdr[5];
+
+		n = sz;
+		if (packet_max - 5 < n)
+			n = packet_max - 5;
+		sprintf(hdr, "%04x", n + 5);
+		hdr[4] = band;
+		safe_write(fd, hdr, 5);
+		safe_write(fd, p, n);
+		p += n;
+		sz -= n;
+	}
+	return ssz;
+}