1 files changed, 50 insertions, 3 deletions
diff --git a/src/pkg/os/env.go b/src/pkg/os/env.go
index 3772c090b..7e3f52502 100644
--- a/src/pkg/os/env.go
+++ b/src/pkg/os/env.go
@@ -6,7 +6,10 @@
 
 package os
 
-func setenv_c(k, v string)
+import (
+	"errors"
+	"syscall"
+)
 
 // Expand replaces ${var} or $var in the string based on the mapping function.
 // Invocations of undefined variables are replaced with the empty string.
@@ -16,9 +19,9 @@ func Expand(s string, mapping func(string) string) string {
 	i := 0
 	for j := 0; j < len(s); j++ {
 		if s[j] == '$' && j+1 < len(s) {
-			buf = append(buf, []byte(s[i:j])...)
+			buf = append(buf, s[i:j]...)
 			name, w := getShellName(s[j+1:])
-			buf = append(buf, []byte(mapping(name))...)
+			buf = append(buf, mapping(name)...)
 			j += w
 			i = j + 1
 		}
@@ -73,3 +76,47 @@ func getShellName(s string) (string, int) {
 	}
 	return s[:i], i
 }
+
+// ENOENV is the error indicating that an environment variable does not exist.
+var ENOENV = errors.New("no such environment variable")
+
+// 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) {
+	if len(key) == 0 {
+		return "", EINVAL
+	}
+	val, found := syscall.Getenv(key)
+	if !found {
+		return "", ENOENV
+	}
+	return val, 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 {
+	err := syscall.Setenv(key, value)
+	if err != nil {
+		return NewSyscallError("setenv", err)
+	}
+	return nil
+}
+
+// Clearenv deletes all environment variables.
+func Clearenv() {
+	syscall.Clearenv()
+}
+
+// Environ returns an array of strings representing the environment,
+// in the form "key=value".
+func Environ() []string {
+	return syscall.Environ()
+}