initial commit. not currently in a working state.

nexgb/auth.go

@@ -0,0 +1,111 @@
+// Copyright 2009 The XGB 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 xgb
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"os"
+)
+
+func getU16BE(r io.Reader, b []byte) (uint16, error) {
+	_, err := io.ReadFull(r, b[0:2])
+	if err != nil {
+		return 0, err
+	}
+	return uint16(b[0])<<8 + uint16(b[1]), nil
+}
+
+func getBytes(r io.Reader, b []byte) ([]byte, error) {
+	n, err := getU16BE(r, b)
+	if err != nil {
+		return nil, err
+	}
+	if int(n) > len(b) {
+		return nil, errors.New("bytes too long for buffer")
+	}
+	_, err = io.ReadFull(r, b[0:n])
+	if err != nil {
+		return nil, err
+	}
+	return b[0:n], nil
+}
+
+func getString(r io.Reader, b []byte) (string, error) {
+	b, err := getBytes(r, b)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}
+
+// readAuthority reads the X authority file for the DISPLAY.
+// If hostname == "" or hostname == "localhost",
+// readAuthority uses the system's hostname (as returned by os.Hostname) instead.
+func readAuthority(hostname, display string) (name string, data []byte, err 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
+
+	if len(hostname) == 0 || hostname == "localhost" {
+		hostname, err = os.Hostname()
+		if err != nil {
+			return "", nil, err
+		}
+	}
+
+	fname := os.Getenv("XAUTHORITY")
+	if len(fname) == 0 {
+		home := os.Getenv("HOME")
+		if len(home) == 0 {
+			err = errors.New("Xauthority not found: $XAUTHORITY, $HOME not set")
+			return "", nil, err
+		}
+		fname = home + "/.Xauthority"
+	}
+
+	r, err := os.Open(fname)
+	if err != nil {
+		return "", nil, err
+	}
+	defer r.Close()
+
+	br := bufio.NewReader(r)
+	for {
+		family, err := getU16BE(br, b[0:2])
+		if err != nil {
+			return "", nil, err
+		}
+
+		addr, err := getString(br, b[0:])
+		if err != nil {
+			return "", nil, err
+		}
+
+		disp, err := getString(br, b[0:])
+		if err != nil {
+			return "", nil, err
+		}
+
+		name0, err := getString(br, b[0:])
+		if err != nil {
+			return "", nil, err
+		}
+
+		data0, err := getBytes(br, b[0:])
+		if err != nil {
+			return "", nil, err
+		}
+
+		if family == familyLocal && addr == hostname && disp == display {
+			return name0, data0, nil
+		}
+	}
+	panic("unreachable")
+}