blob: 82dd58c28a497a273ed4cb3e2c9669121d377aa3 [file] [log] [blame]
// 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"
)
// Reads the DISPLAY environment variable, and returns the "12" in ":12.0".
func getDisplay() string {
d := os.Getenv("DISPLAY")
if len(d) < 1 || d[0] != ':' {
return ""
}
i := 1
for ; i < len(d); i++ {
if d[i] < '0' || d[i] > '9' {
break
}
}
return d[1:i]
}
// 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
}
// Reads a length-prefixed string from r, using b as a scratch buffer.
func readStr(r io.Reader, b []byte) (s string, err os.Error) {
n, err := readU16BE(r, b)
if err != nil {
return
}
if int(n) > len(b) {
return s, os.NewError("Xauthority entry too long for buffer")
}
_, err = io.ReadFull(r, b[0:n])
if err != nil {
return
}
return string(b[0:n]), nil
}
// Reads the ~/.Xauthority file and returns the name/data pair for the DISPLAY.
// 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).
func readAuth(b []byte) (name, data string, err os.Error) {
// As per /usr/include/X11/Xauth.h.
const familyLocal = 256
home := os.Getenv("HOME")
if len(home) == 0 {
err = os.NewError("unknown HOME")
return
}
r, err := os.Open(home+"/.Xauthority", os.O_RDONLY, 0444)
if err != nil {
return
}
defer r.Close()
br := bufio.NewReader(r)
hostname, err := os.Hostname()
if err != nil {
return
}
display := getDisplay()
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 == display {
return name0, data0, nil
}
}
panic("unreachable")
}