| // 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) |
| if err != nil { |
| return |
| } |
| defer r.Close() |
| br := bufio.NewReader(r) |
| |
| hostname, err := os.Hostname() |
| if err != nil { |
| return |
| } |
| for { |
| var family uint16 |
| var addr, disp, name0, data0 string |
| 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") |
| } |