1 files changed, 93 insertions, 0 deletions
diff --git a/libgo/go/exp/draw/x11/auth.go b/libgo/go/exp/draw/x11/auth.go
new file mode 100644
index 00000000000..896dedf05c7
--- /dev/null
+++ b/libgo/go/exp/draw/x11/auth.go
@@ -0,0 +1,93 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package x11
+
+import (
+	"bufio"
+	"io"
+	"os"
+)
+
+// readU16BE reads a big-endian uint16 from r, using b as a scratch buffer.
+func readU16BE(r io.Reader, b []byte) (uint16, os.Error) {
+	_, err := io.ReadFull(r, b[0:2])
+	if err != nil {
+		return 0, err
+	}
+	return uint16(b[0])<<8 + uint16(b[1]), nil
+}
+
+// readStr reads a length-prefixed string from r, using b as a scratch buffer.
+func readStr(r io.Reader, b []byte) (string, os.Error) {
+	n, err := readU16BE(r, b)
+	if err != nil {
+		return "", err
+	}
+	if int(n) > len(b) {
+		return "", os.NewError("Xauthority entry too long for buffer")
+	}
+	_, err = io.ReadFull(r, b[0:n])
+	if err != nil {
+		return "", err
+	}
+	return string(b[0:n]), nil
+}
+
+// readAuth reads the X authority file and returns the name/data pair for the display.
+// displayStr is the "12" out of a $DISPLAY like ":12.0".
+func readAuth(displayStr string) (name, data string, err os.Error) {
+	// b is a scratch buffer to use and should be at least 256 bytes long
+	// (i.e. it should be able to hold a hostname).
+	var b [256]byte
+	// As per /usr/include/X11/Xauth.h.
+	const familyLocal = 256
+
+	fn := os.Getenv("XAUTHORITY")
+	if fn == "" {
+		home := os.Getenv("HOME")
+		if home == "" {
+			err = os.NewError("Xauthority not found: $XAUTHORITY, $HOME not set")
+			return
+		}
+		fn = home + "/.Xauthority"
+	}
+	r, err := os.Open(fn, os.O_RDONLY, 0444)
+	if err != nil {
+		return
+	}
+	defer r.Close()
+	br := bufio.NewReader(r)
+
+	hostname, err := os.Hostname()
+	if err != nil {
+		return
+	}
+	for {
+		family, err := readU16BE(br, b[0:2])
+		if err != nil {
+			return
+		}
+		addr, err := readStr(br, b[0:])
+		if err != nil {
+			return
+		}
+		disp, err := readStr(br, b[0:])
+		if err != nil {
+			return
+		}
+		name0, err := readStr(br, b[0:])
+		if err != nil {
+			return
+		}
+		data0, err := readStr(br, b[0:])
+		if err != nil {
+			return
+		}
+		if family == familyLocal && addr == hostname && disp == displayStr {
+			return name0, data0, nil
+		}
+	}
+	panic("unreachable")
+}