libgo/go/os/sys_linux.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package os
   6
   7 import (
   8         "runtime"
   9         "syscall"
  10 )
  11
  12 func hostname() (name string, err error) {
  13         // Try uname first, as it's only one system call and reading
  14         // from /proc is not allowed on Android.
  15         var un syscall.Utsname
  16         err = syscall.Uname(&un)
  17
  18         var buf [512]byte // Enough for a DNS name.
  19         for i, b := range un.Nodename[:] {
  20                 buf[i] = uint8(b)
  21                 if b == 0 {
  22                         name = string(buf[:i])
  23                         break
  24                 }
  25         }
  26         // If we got a name and it's not potentially truncated
  27         // (Nodename is 65 bytes), return it.
  28         if err == nil && len(name) > 0 && len(name) < 64 {
  29                 return name, nil
  30         }
  31         if runtime.GOOS == "android" {
  32                 if name != "" {
  33                         return name, nil
  34                 }
  35                 return "localhost", nil
  36         }
  37
  38         f, err := Open("/proc/sys/kernel/hostname")
  39         if err != nil {
  40                 return "", err
  41         }
  42         defer f.Close()
  43
  44         n, err := f.Read(buf[:])
  45         if err != nil {
  46                 return "", err
  47         }
  48
  49         if n > 0 && buf[n-1] == '\n' {
  50                 n--
  51         }
  52         return string(buf[:n]), nil
  53 }