114 lines
2.3 KiB
Go
114 lines
2.3 KiB
Go
// Copyright 2009 The XGB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package xgb
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import (
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"bufio"
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"errors"
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"io"
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"os"
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)
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// readAuthority reads the X authority file for the DISPLAY.
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// If hostname == "" or hostname == "localhost",
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// then use the system's hostname (as returned by os.Hostname) instead.
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func readAuthority(hostname, display string) (
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name string, data []byte, err error) {
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// b is a scratch buffer to use and should be at least 256 bytes long
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// (i.e. it should be able to hold a hostname).
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var b [256]byte
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// As per /usr/include/X11/Xauth.h.
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const familyLocal = 256
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if len(hostname) == 0 || hostname == "localhost" {
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hostname, err = os.Hostname()
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if err != nil {
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return "", nil, err
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}
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}
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fname := os.Getenv("XAUTHORITY")
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if len(fname) == 0 {
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home := os.Getenv("HOME")
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if len(home) == 0 {
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err = errors.New("Xauthority not found: $XAUTHORITY, $HOME not set")
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return "", nil, err
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}
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fname = home + "/.Xauthority"
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}
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r, err := os.Open(fname)
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if err != nil {
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return "", nil, err
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}
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defer r.Close()
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br := bufio.NewReader(r)
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for {
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family, err := getU16BE(br, b[0:2])
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if err != nil {
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return "", nil, err
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}
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addr, err := getString(br, b[0:])
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if err != nil {
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return "", nil, err
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}
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disp, err := getString(br, b[0:])
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if err != nil {
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return "", nil, err
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}
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name0, err := getString(br, b[0:])
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if err != nil {
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return "", nil, err
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}
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data0, err := getBytes(br, b[0:])
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if err != nil {
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return "", nil, err
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}
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if family == familyLocal && addr == hostname && disp == display {
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return name0, data0, nil
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}
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}
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panic("unreachable")
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}
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func getU16BE(r io.Reader, b []byte) (uint16, error) {
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_, err := io.ReadFull(r, b[0:2])
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if err != nil {
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return 0, err
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}
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return uint16(b[0])<<8 + uint16(b[1]), nil
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}
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func getBytes(r io.Reader, b []byte) ([]byte, error) {
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n, err := getU16BE(r, b)
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if err != nil {
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return nil, err
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}
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if int(n) > len(b) {
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return nil, errors.New("bytes too long for buffer")
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}
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_, err = io.ReadFull(r, b[0:n])
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if err != nil {
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return nil, err
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}
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return b[0:n], nil
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}
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func getString(r io.Reader, b []byte) (string, error) {
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b, err := getBytes(r, b)
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if err != nil {
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return "", err
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}
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return string(b), nil
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}
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