1 files changed, 151 insertions, 0 deletions
diff --git a/sideband.c b/sideband.c
new file mode 100644
index 0000000..d5ffa1c
--- /dev/null
+++ b/sideband.c
@@ -0,0 +1,151 @@
+#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)
+{
+	unsigned pf = strlen(PREFIX);
+	unsigned sf;
+	char buf[LARGE_PACKET_MAX + 2*FIX_SIZE];
+	char *suffix, *term;
+	int skip_pf = 0;
+
+	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) {
+			fprintf(stderr, "%s: protocol error: no band designator\n", me);
+			return SIDEBAND_PROTOCOL_ERROR;
+		}
+		band = buf[pf] & 0xff;
+		len--;
+		switch (band) {
+		case 3:
+			buf[pf] = ' ';
+			buf[pf+1+len] = '\0';
+			fprintf(stderr, "%s\n", buf);
+			return SIDEBAND_REMOTE_ERROR;
+		case 2:
+			buf[pf] = ' ';
+			do {
+				char *b = buf;
+				int brk = 0;
+
+				/*
+				 * If the last buffer didn't end with a line
+				 * break then we should not print a prefix
+				 * this time around.
+				 */
+				if (skip_pf) {
+					b += pf+1;
+				} else {
+					len += pf+1;
+					brk += pf+1;
+				}
+
+				/* Look for a line break. */
+				for (;;) {
+					brk++;
+					if (brk > len) {
+						brk = 0;
+						break;
+					}
+					if (b[brk-1] == '\n' ||
+					    b[brk-1] == '\r')
+						break;
+				}
+
+				/*
+				 * Let's insert a suffix to clear the end
+				 * of the screen line if a line break was
+				 * found.  Also, if we don't skip the
+				 * prefix, then a non-empty string must be
+				 * present too.
+				 */
+				if (brk > (skip_pf ? 0 : (pf+1 + 1))) {
+					char save[FIX_SIZE];
+					memcpy(save, b + brk, sf);
+					b[brk + sf - 1] = b[brk - 1];
+					memcpy(b + brk - 1, suffix, sf);
+					fprintf(stderr, "%.*s", brk + sf, b);
+					memcpy(b + brk, save, sf);
+					len -= brk;
+				} else {
+					int l = brk ? brk : len;
+					fprintf(stderr, "%.*s", l, b);
+					len -= l;
+				}
+
+				skip_pf = !brk;
+				memmove(buf + pf+1, b + brk, len);
+			} while (len);
+			continue;
+		case 1:
+			safe_write(out, buf + pf+1, len);
+			continue;
+		default:
+			fprintf(stderr, "%s: protocol error: bad band #%d\n",
+				me, band);
+			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;
+		if (0 <= band) {
+			sprintf(hdr, "%04x", n + 5);
+			hdr[4] = band;
+			safe_write(fd, hdr, 5);
+		} else {
+			sprintf(hdr, "%04x", n + 4);
+			safe_write(fd, hdr, 4);
+		}
+		safe_write(fd, p, n);
+		p += n;
+		sz -= n;
+	}
+	return ssz;
+}