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  }
    54
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