1 files changed, 129 insertions, 0 deletions
diff --git a/sideband.c b/sideband.c
new file mode 100644
index 0000000..b677781
--- /dev/null
+++ b/sideband.c
@@ -0,0 +1,129 @@
+#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.
+ */
+
+#define PREFIX "remote:"
+
+#define ANSI_SUFFIX "\033[K"
+#define DUMB_SUFFIX "        "
+
+#define FIX_SIZE 10  /* large enough for any of the above */
+
+int recv_sideband(const char *me, int in_stream, int out, int err)
+{
+	unsigned pf = strlen(PREFIX);
+	unsigned sf;
+	char buf[LARGE_PACKET_MAX + 2*FIX_SIZE];
+	char *suffix, *term;
+
+	memcpy(buf, PREFIX, pf);
+	term = getenv("TERM");
+	if (term && strcmp(term, "dumb"))
+		suffix = ANSI_SUFFIX;
+	else
+		suffix = DUMB_SUFFIX;
+	sf = strlen(suffix);
+
+	while (1) {
+		int band, len;
+		len = packet_read_line(in_stream, buf + pf, 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[pf] & 0xff;
+		len--;
+		switch (band) {
+		case 3:
+			buf[pf] = ' ';
+			buf[pf+1+len] = '\n';
+			safe_write(err, buf, pf+1+len+1);
+			return SIDEBAND_REMOTE_ERROR;
+		case 2:
+			buf[pf] = ' ';
+			len += pf+1;
+			while (1) {
+				int brk = pf+1;
+
+				/* Break the buffer into separate lines. */
+				while (brk < len) {
+					brk++;
+					if (buf[brk-1] == '\n' ||
+					    buf[brk-1] == '\r')
+						break;
+				}
+
+				/*
+				 * Let's insert a suffix to clear the end
+				 * of the screen line, but only if current
+				 * line data actually contains something.
+				 */
+				if (brk > pf+1 + 1) {
+					char save[FIX_SIZE];
+					memcpy(save, buf + brk, sf);
+					buf[brk + sf - 1] = buf[brk - 1];
+					memcpy(buf + brk - 1, suffix, sf);
+					safe_write(err, buf, brk + sf);
+					memcpy(buf + brk, save, sf);
+				} else
+					safe_write(err, buf, brk);
+
+				if (brk < len) {
+					memmove(buf + pf+1, buf + brk, len - brk);
+					len = len - brk + pf+1;
+				} else
+					break;
+			}
+			continue;
+		case 1:
+			safe_write(out, buf + pf+1, 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;
+}