1 files changed, 242 insertions, 0 deletions
diff --git a/pkt-line.c b/pkt-line.c
new file mode 100644
index 0000000..eaba15f
--- /dev/null
+++ b/pkt-line.c
@@ -0,0 +1,242 @@
+#include "cache.h"
+#include "pkt-line.h"
+
+static const char *packet_trace_prefix = "git";
+static const char trace_key[] = "GIT_TRACE_PACKET";
+
+void packet_trace_identity(const char *prog)
+{
+	packet_trace_prefix = xstrdup(prog);
+}
+
+static void packet_trace(const char *buf, unsigned int len, int write)
+{
+	int i;
+	struct strbuf out;
+
+	if (!trace_want(trace_key))
+		return;
+
+	/* +32 is just a guess for header + quoting */
+	strbuf_init(&out, len+32);
+
+	strbuf_addf(&out, "packet: %12s%c ",
+		    packet_trace_prefix, write ? '>' : '<');
+
+	if ((len >= 4 && !prefixcmp(buf, "PACK")) ||
+	    (len >= 5 && !prefixcmp(buf+1, "PACK"))) {
+		strbuf_addstr(&out, "PACK ...");
+		unsetenv(trace_key);
+	}
+	else {
+		/* XXX we should really handle printable utf8 */
+		for (i = 0; i < len; i++) {
+			/* suppress newlines */
+			if (buf[i] == '\n')
+				continue;
+			if (buf[i] >= 0x20 && buf[i] <= 0x7e)
+				strbuf_addch(&out, buf[i]);
+			else
+				strbuf_addf(&out, "\\%o", buf[i]);
+		}
+	}
+
+	strbuf_addch(&out, '\n');
+	trace_strbuf(trace_key, &out);
+	strbuf_release(&out);
+}
+
+/*
+ * Write a packetized stream, where each line is preceded by
+ * its length (including the header) as a 4-byte hex number.
+ * A length of 'zero' means end of stream (and a length of 1-3
+ * would be an error).
+ *
+ * This is all pretty stupid, but we use this packetized line
+ * format to make a streaming format possible without ever
+ * over-running the read buffers. That way we'll never read
+ * into what might be the pack data (which should go to another
+ * process entirely).
+ *
+ * The writing side could use stdio, but since the reading
+ * side can't, we stay with pure read/write interfaces.
+ */
+ssize_t safe_write(int fd, const void *buf, ssize_t n)
+{
+	ssize_t nn = n;
+	while (n) {
+		int ret = xwrite(fd, buf, n);
+		if (ret > 0) {
+			buf = (char *) buf + ret;
+			n -= ret;
+			continue;
+		}
+		if (!ret)
+			die("write error (disk full?)");
+		die_errno("write error");
+	}
+	return nn;
+}
+
+/*
+ * If we buffered things up above (we don't, but we should),
+ * we'd flush it here
+ */
+void packet_flush(int fd)
+{
+	packet_trace("0000", 4, 1);
+	safe_write(fd, "0000", 4);
+}
+
+void packet_buf_flush(struct strbuf *buf)
+{
+	packet_trace("0000", 4, 1);
+	strbuf_add(buf, "0000", 4);
+}
+
+#define hex(a) (hexchar[(a) & 15])
+static char buffer[1000];
+static unsigned format_packet(const char *fmt, va_list args)
+{
+	static char hexchar[] = "0123456789abcdef";
+	unsigned n;
+
+	n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
+	if (n >= sizeof(buffer)-4)
+		die("protocol error: impossibly long line");
+	n += 4;
+	buffer[0] = hex(n >> 12);
+	buffer[1] = hex(n >> 8);
+	buffer[2] = hex(n >> 4);
+	buffer[3] = hex(n);
+	packet_trace(buffer+4, n-4, 1);
+	return n;
+}
+
+void packet_write(int fd, const char *fmt, ...)
+{
+	va_list args;
+	unsigned n;
+
+	va_start(args, fmt);
+	n = format_packet(fmt, args);
+	va_end(args);
+	safe_write(fd, buffer, n);
+}
+
+void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
+{
+	va_list args;
+	unsigned n;
+
+	va_start(args, fmt);
+	n = format_packet(fmt, args);
+	va_end(args);
+	strbuf_add(buf, buffer, n);
+}
+
+static int safe_read(int fd, void *buffer, unsigned size, int return_line_fail)
+{
+	ssize_t ret = read_in_full(fd, buffer, size);
+	if (ret < 0)
+		die_errno("read error");
+	else if (ret < size) {
+		if (return_line_fail)
+			return -1;
+
+		die("The remote end hung up unexpectedly");
+	}
+
+	return ret;
+}
+
+static int packet_length(const char *linelen)
+{
+	int n;
+	int len = 0;
+
+	for (n = 0; n < 4; n++) {
+		unsigned char c = linelen[n];
+		len <<= 4;
+		if (c >= '0' && c <= '9') {
+			len += c - '0';
+			continue;
+		}
+		if (c >= 'a' && c <= 'f') {
+			len += c - 'a' + 10;
+			continue;
+		}
+		if (c >= 'A' && c <= 'F') {
+			len += c - 'A' + 10;
+			continue;
+		}
+		return -1;
+	}
+	return len;
+}
+
+static int packet_read_internal(int fd, char *buffer, unsigned size, int return_line_fail)
+{
+	int len, ret;
+	char linelen[4];
+
+	ret = safe_read(fd, linelen, 4, return_line_fail);
+	if (return_line_fail && ret < 0)
+		return ret;
+	len = packet_length(linelen);
+	if (len < 0)
+		die("protocol error: bad line length character: %.4s", linelen);
+	if (!len) {
+		packet_trace("0000", 4, 0);
+		return 0;
+	}
+	len -= 4;
+	if (len >= size)
+		die("protocol error: bad line length %d", len);
+	ret = safe_read(fd, buffer, len, return_line_fail);
+	if (return_line_fail && ret < 0)
+		return ret;
+	buffer[len] = 0;
+	packet_trace(buffer, len, 0);
+	return len;
+}
+
+int packet_read(int fd, char *buffer, unsigned size)
+{
+	return packet_read_internal(fd, buffer, size, 1);
+}
+
+int packet_read_line(int fd, char *buffer, unsigned size)
+{
+	return packet_read_internal(fd, buffer, size, 0);
+}
+
+int packet_get_line(struct strbuf *out,
+	char **src_buf, size_t *src_len)
+{
+	int len;
+
+	if (*src_len < 4)
+		return -1;
+	len = packet_length(*src_buf);
+	if (len < 0)
+		return -1;
+	if (!len) {
+		*src_buf += 4;
+		*src_len -= 4;
+		packet_trace("0000", 4, 0);
+		return 0;
+	}
+	if (*src_len < len)
+		return -2;
+
+	*src_buf += 4;
+	*src_len -= 4;
+	len -= 4;
+
+	strbuf_add(out, *src_buf, len);
+	*src_buf += len;
+	*src_len -= len;
+	packet_trace(out->buf, out->len, 0);
+	return len;
+}