| // 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") |
| } |