syscall: make Environ return original order
Fixes #2619
R=r, rsc
CC=golang-dev
https://golang.org/cl/5528058
diff --git a/src/pkg/syscall/env_unix.go b/src/pkg/syscall/env_unix.go
index 2c873cbb..8b1868c 100644
--- a/src/pkg/syscall/env_unix.go
+++ b/src/pkg/syscall/env_unix.go
@@ -10,26 +10,40 @@
import "sync"
-var env map[string]string
-var envOnce sync.Once
-var envs []string // provided by runtime
+var (
+ // envOnce guards initialization by copyenv, which populates env.
+ envOnce sync.Once
+ // envLock guards env and envs.
+ envLock sync.RWMutex
+
+ // env maps from an environment variable to its first occurrence in envs.
+ env map[string]int
+
+ // envs is provided by the runtime. elements are expected to be
+ // of the form "key=value".
+ envs []string
+)
+
+// setenv_c is provided by the runtime, but is a no-op if cgo isn't
+// loaded.
func setenv_c(k, v string)
func copyenv() {
- env = make(map[string]string)
- for _, s := range envs {
+ env = make(map[string]int)
+ for i, s := range envs {
for j := 0; j < len(s); j++ {
if s[j] == '=' {
- env[s[0:j]] = s[j+1:]
+ key := s[:j]
+ if _, ok := env[key]; !ok {
+ env[key] = i
+ }
break
}
}
}
}
-var envLock sync.RWMutex
-
func Getenv(key string) (value string, found bool) {
envOnce.Do(copyenv)
if len(key) == 0 {
@@ -39,11 +53,17 @@
envLock.RLock()
defer envLock.RUnlock()
- v, ok := env[key]
+ i, ok := env[key]
if !ok {
return "", false
}
- return v, true
+ s := envs[i]
+ for i := 0; i < len(s); i++ {
+ if s[i] == '=' {
+ return s[i+1:], true
+ }
+ }
+ return "", false
}
func Setenv(key, value string) error {
@@ -55,8 +75,16 @@
envLock.Lock()
defer envLock.Unlock()
- env[key] = value
- setenv_c(key, value) // is a no-op if cgo isn't loaded
+ i, ok := env[key]
+ kv := key + "=" + value
+ if ok {
+ envs[i] = kv
+ } else {
+ i = len(envs)
+ envs = append(envs, kv)
+ }
+ env[key] = i
+ setenv_c(key, value)
return nil
}
@@ -66,8 +94,8 @@
envLock.Lock()
defer envLock.Unlock()
- env = make(map[string]string)
-
+ env = make(map[string]int)
+ envs = []string{}
// TODO(bradfitz): pass through to C
}
@@ -75,11 +103,7 @@
envOnce.Do(copyenv)
envLock.RLock()
defer envLock.RUnlock()
- a := make([]string, len(env))
- i := 0
- for k, v := range env {
- a[i] = k + "=" + v
- i++
- }
+ a := make([]string, len(envs))
+ copy(a, envs)
return a
}
