1 files changed, 80 insertions, 3 deletions
diff --git a/src/pkg/os/env_unix.go b/src/pkg/os/env_unix.go
index 0c13bda0e..e7e1c3b90 100755..100644
--- a/src/pkg/os/env_unix.go
+++ b/src/pkg/os/env_unix.go
@@ -6,10 +6,87 @@
 
 package os
 
+import (
+	"sync"
+)
+
+// ENOENV is the Error indicating that an environment variable does not exist.
+var ENOENV = NewError("no such environment variable")
+
+var env map[string]string
+var once sync.Once
+
+
+func copyenv() {
+	env = make(map[string]string)
+	for _, s := range Envs {
+		for j := 0; j < len(s); j++ {
+			if s[j] == '=' {
+				env[s[0:j]] = s[j+1:]
+				break
+			}
+		}
+	}
+}
+
+// Getenverror retrieves the value of the environment variable named by the key.
+// It returns the value and an error, if any.
+func Getenverror(key string) (value string, err Error) {
+	once.Do(copyenv)
+
+	if len(key) == 0 {
+		return "", EINVAL
+	}
+	v, ok := env[key]
+	if !ok {
+		return "", ENOENV
+	}
+	return v, nil
+}
+
+// Getenv retrieves the value of the environment variable named by the key.
+// It returns the value, which will be empty if the variable is not present.
+func Getenv(key string) string {
+	v, _ := Getenverror(key)
+	return v
+}
+
+// Setenv sets the value of the environment variable named by the key.
+// It returns an Error, if any.
+func Setenv(key, value string) Error {
+	once.Do(copyenv)
+
+	if len(key) == 0 {
+		return EINVAL
+	}
+	env[key] = value
+	return nil
+}
+
+// Clearenv deletes all environment variables.
+func Clearenv() {
+	once.Do(copyenv) // prevent copyenv in Getenv/Setenv
+	env = make(map[string]string)
+}
+
+// Environ returns an array of strings representing the environment,
+// in the form "key=value".
+func Environ() []string {
+	once.Do(copyenv)
+	a := make([]string, len(env))
+	i := 0
+	for k, v := range env {
+		// check i < len(a) for safety,
+		// in case env is changing underfoot.
+		if i < len(a) {
+			a[i] = k + "=" + v
+			i++
+		}
+	}
+	return a[0:i]
+}
+
 // TempDir returns the default directory to use for temporary files.
-// On Unix-like systems, it uses the environment variable $TMPDIR
-// or, if that is empty, /tmp.
-// On Windows systems, it uses the Windows GetTempPath API.
 func TempDir() string {
 	dir := Getenv("TMPDIR")
 	if dir == "" {