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Source file src/syscall/env_windows.go

Documentation: syscall

  // Copyright 2010 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.
  
  // Windows environment variables.
  
  package syscall
  
  import (
  	"unicode/utf16"
  	"unsafe"
  )
  
  func Getenv(key string) (value string, found bool) {
  	keyp, err := UTF16PtrFromString(key)
  	if err != nil {
  		return "", false
  	}
  	n := uint32(100)
  	for {
  		b := make([]uint16, n)
  		n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
  		if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
  			return "", false
  		}
  		if n <= uint32(len(b)) {
  			return string(utf16.Decode(b[:n])), true
  		}
  	}
  }
  
  func Setenv(key, value string) error {
  	v, err := UTF16PtrFromString(value)
  	if err != nil {
  		return err
  	}
  	keyp, err := UTF16PtrFromString(key)
  	if err != nil {
  		return err
  	}
  	e := SetEnvironmentVariable(keyp, v)
  	if e != nil {
  		return e
  	}
  	return nil
  }
  
  func Unsetenv(key string) error {
  	keyp, err := UTF16PtrFromString(key)
  	if err != nil {
  		return err
  	}
  	return SetEnvironmentVariable(keyp, nil)
  }
  
  func Clearenv() {
  	for _, s := range Environ() {
  		// Environment variables can begin with =
  		// so start looking for the separator = at j=1.
  		// http://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
  		for j := 1; j < len(s); j++ {
  			if s[j] == '=' {
  				Unsetenv(s[0:j])
  				break
  			}
  		}
  	}
  }
  
  func Environ() []string {
  	s, e := GetEnvironmentStrings()
  	if e != nil {
  		return nil
  	}
  	defer FreeEnvironmentStrings(s)
  	r := make([]string, 0, 50) // Empty with room to grow.
  	for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
  		if p[i] == 0 {
  			// empty string marks the end
  			if i <= from {
  				break
  			}
  			r = append(r, string(utf16.Decode(p[from:i])))
  			from = i + 1
  		}
  	}
  	return r
  }
  

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