github.com/spotify/syslog-redirector-golang@v0.0.0-20140320174030-4859f03d829a/src/pkg/syscall/env_windows.go (about)

     1  // Copyright 2010 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  // Windows environment variables.
     6  
     7  package syscall
     8  
     9  import (
    10  	"unicode/utf16"
    11  	"unsafe"
    12  )
    13  
    14  func Getenv(key string) (value string, found bool) {
    15  	keyp, err := UTF16PtrFromString(key)
    16  	if err != nil {
    17  		return "", false
    18  	}
    19  	b := make([]uint16, 100)
    20  	n, e := GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
    21  	if n == 0 && e == ERROR_ENVVAR_NOT_FOUND {
    22  		return "", false
    23  	}
    24  	if n > uint32(len(b)) {
    25  		b = make([]uint16, n)
    26  		n, e = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
    27  		if n > uint32(len(b)) {
    28  			n = 0
    29  		}
    30  	}
    31  	return string(utf16.Decode(b[0:n])), true
    32  }
    33  
    34  func Setenv(key, value string) error {
    35  	v, err := UTF16PtrFromString(value)
    36  	if err != nil {
    37  		return err
    38  	}
    39  	keyp, err := UTF16PtrFromString(key)
    40  	if err != nil {
    41  		return err
    42  	}
    43  	e := SetEnvironmentVariable(keyp, v)
    44  	if e != nil {
    45  		return e
    46  	}
    47  	return nil
    48  }
    49  
    50  func Clearenv() {
    51  	for _, s := range Environ() {
    52  		// Environment variables can begin with =
    53  		// so start looking for the separator = at j=1.
    54  		// http://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
    55  		for j := 1; j < len(s); j++ {
    56  			if s[j] == '=' {
    57  				Setenv(s[0:j], "")
    58  				break
    59  			}
    60  		}
    61  	}
    62  }
    63  
    64  func Environ() []string {
    65  	s, e := GetEnvironmentStrings()
    66  	if e != nil {
    67  		return nil
    68  	}
    69  	defer FreeEnvironmentStrings(s)
    70  	r := make([]string, 0, 50) // Empty with room to grow.
    71  	for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
    72  		if p[i] == 0 {
    73  			// empty string marks the end
    74  			if i <= from {
    75  				break
    76  			}
    77  			r = append(r, string(utf16.Decode(p[from:i])))
    78  			from = i + 1
    79  		}
    80  	}
    81  	return r
    82  }