Source file src/syscall/env_windows.go

     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		n := uint32(100)
    20		for {
    21			b := make([]uint16, n)
    22			n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
    23			if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
    24				return "", false
    25			}
    26			if n <= uint32(len(b)) {
    27				return string(utf16.Decode(b[:n])), true
    28			}
    29		}
    30	}
    31	
    32	func Setenv(key, value string) error {
    33		v, err := UTF16PtrFromString(value)
    34		if err != nil {
    35			return err
    36		}
    37		keyp, err := UTF16PtrFromString(key)
    38		if err != nil {
    39			return err
    40		}
    41		e := SetEnvironmentVariable(keyp, v)
    42		if e != nil {
    43			return e
    44		}
    45		return nil
    46	}
    47	
    48	func Unsetenv(key string) error {
    49		keyp, err := UTF16PtrFromString(key)
    50		if err != nil {
    51			return err
    52		}
    53		return SetEnvironmentVariable(keyp, nil)
    54	}
    55	
    56	func Clearenv() {
    57		for _, s := range Environ() {
    58			// Environment variables can begin with =
    59			// so start looking for the separator = at j=1.
    60			// https://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
    61			for j := 1; j < len(s); j++ {
    62				if s[j] == '=' {
    63					Unsetenv(s[0:j])
    64					break
    65				}
    66			}
    67		}
    68	}
    69	
    70	func Environ() []string {
    71		s, e := GetEnvironmentStrings()
    72		if e != nil {
    73			return nil
    74		}
    75		defer FreeEnvironmentStrings(s)
    76		r := make([]string, 0, 50) // Empty with room to grow.
    77		for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
    78			if p[i] == 0 {
    79				// empty string marks the end
    80				if i <= from {
    81					break
    82				}
    83				r = append(r, string(utf16.Decode(p[from:i])))
    84				from = i + 1
    85			}
    86		}
    87		return r
    88	}
    89	

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