github.com/hbdrawn/golang@v0.0.0-20141214014649-6b835209aba2/src/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 Unsetenv(key string) error {
    51  	keyp, err := UTF16PtrFromString(key)
    52  	if err != nil {
    53  		return err
    54  	}
    55  	return SetEnvironmentVariable(keyp, nil)
    56  }
    57  
    58  func Clearenv() {
    59  	for _, s := range Environ() {
    60  		// Environment variables can begin with =
    61  		// so start looking for the separator = at j=1.
    62  		// http://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
    63  		for j := 1; j < len(s); j++ {
    64  			if s[j] == '=' {
    65  				Setenv(s[0:j], "")
    66  				break
    67  			}
    68  		}
    69  	}
    70  }
    71  
    72  func Environ() []string {
    73  	s, e := GetEnvironmentStrings()
    74  	if e != nil {
    75  		return nil
    76  	}
    77  	defer FreeEnvironmentStrings(s)
    78  	r := make([]string, 0, 50) // Empty with room to grow.
    79  	for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
    80  		if p[i] == 0 {
    81  			// empty string marks the end
    82  			if i <= from {
    83  				break
    84  			}
    85  			r = append(r, string(utf16.Decode(p[from:i])))
    86  			from = i + 1
    87  		}
    88  	}
    89  	return r
    90  }