1 files changed, 96 insertions, 0 deletions
diff --git a/src/syscall/env_windows.go b/src/syscall/env_windows.go
new file mode 100644
index 0000000..220a005
--- /dev/null
+++ b/src/syscall/env_windows.go
@@ -0,0 +1,96 @@
+// 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 (
+	"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 UTF16ToString(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
+	}
+	runtimeSetenv(key, value)
+	return nil
+}
+
+func Unsetenv(key string) error {
+	keyp, err := UTF16PtrFromString(key)
+	if err != nil {
+		return err
+	}
+	e := SetEnvironmentVariable(keyp, nil)
+	if e != nil {
+		return e
+	}
+	runtimeUnsetenv(key)
+	return nil
+}
+
+func Clearenv() {
+	for _, s := range Environ() {
+		// Environment variables can begin with =
+		// so start looking for the separator = at j=1.
+		// https://devblogs.microsoft.com/oldnewthing/20100506-00/?p=14133
+		for j := 1; j < len(s); j++ {
+			if s[j] == '=' {
+				Unsetenv(s[0:j])
+				break
+			}
+		}
+	}
+}
+
+func Environ() []string {
+	envp, e := GetEnvironmentStrings()
+	if e != nil {
+		return nil
+	}
+	defer FreeEnvironmentStrings(envp)
+
+	r := make([]string, 0, 50) // Empty with room to grow.
+	const size = unsafe.Sizeof(*envp)
+	for *envp != 0 { // environment block ends with empty string
+		// find NUL terminator
+		end := unsafe.Pointer(envp)
+		for *(*uint16)(end) != 0 {
+			end = unsafe.Add(end, size)
+		}
+
+		entry := unsafe.Slice(envp, (uintptr(end)-uintptr(unsafe.Pointer(envp)))/size)
+		r = append(r, UTF16ToString(entry))
+		envp = (*uint16)(unsafe.Add(end, size))
+	}
+	return r
+}