Imported Upstream version 4.8.1

[platform/upstream/gcc48.git] / libgo / go / syscall / env_plan9.go

diff --git a/libgo/go/syscall/env_plan9.go b/libgo/go/syscall/env_plan9.go
index 2848d9b..0f89aa9 100644 (file)
--- a/libgo/go/syscall/env_plan9.go
+++ b/libgo/go/syscall/env_plan9.go
@@ -12,14 +12,17 @@ import (
 )
 
 var (
-       // envOnce guards initialization by copyenv, which populates env.
+       // envOnce guards copyenv, which populates env.
        envOnce sync.Once
 
        // envLock guards env.
        envLock sync.RWMutex
 
        // env maps from an environment variable to its value.
-       env map[string]string
+       env = make(map[string]string)
+
+       errZeroLengthKey = errors.New("zero length key")
+       errShortWrite    = errors.New("i/o count too small")
 )
 
 func readenv(key string) (string, error) {
@@ -47,12 +50,18 @@ func writeenv(key, value string) error {
                return err
        }
        defer Close(fd)
-       _, err = Write(fd, []byte(value))
-       return err
+       b := []byte(value)
+       n, err := Write(fd, b)
+       if err != nil {
+               return err
+       }
+       if n != len(b) {
+               return errShortWrite
+       }
+       return nil
 }
 
 func copyenv() {
-       env = make(map[string]string)
        fd, err := Open("/env", O_RDONLY)
        if err != nil {
                return
@@ -72,7 +81,6 @@ func copyenv() {
 }
 
 func Getenv(key string) (value string, found bool) {
-       envOnce.Do(copyenv)
        if len(key) == 0 {
                return "", false
        }
@@ -80,17 +88,20 @@ func Getenv(key string) (value string, found bool) {
        envLock.RLock()
        defer envLock.RUnlock()
 
-       v, ok := env[key]
-       if !ok {
+       if v, ok := env[key]; ok {
+               return v, true
+       }
+       v, err := readenv(key)
+       if err != nil {
                return "", false
        }
+       env[key] = v
        return v, true
 }
 
 func Setenv(key, value string) error {
-       envOnce.Do(copyenv)
        if len(key) == 0 {
-               return errors.New("zero length key")
+               return errZeroLengthKey
        }
 
        envLock.Lock()
@@ -105,8 +116,6 @@ func Setenv(key, value string) error {
 }
 
 func Clearenv() {
-       envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv
-
        envLock.Lock()
        defer envLock.Unlock()
 
@@ -115,9 +124,10 @@ func Clearenv() {
 }
 
 func Environ() []string {
-       envOnce.Do(copyenv)
        envLock.RLock()
        defer envLock.RUnlock()
+
+       envOnce.Do(copyenv)
        a := make([]string, len(env))
        i := 0
        for k, v := range env {