From: Rob Pike <r@golang.org>
Date: Tue, 5 May 2015 18:17:08 +0000 (-0700)
Subject: os: add LookupEnv, like Getenv but reports presence
X-Git-Tag: go1.5beta1~743
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=e8c0d0f2f3d1e7b1ccc8f057cff24a490b2dc2a7;p=gostls13.git

os: add LookupEnv, like Getenv but reports presence

Fixes #9676.

Change-Id: I32fe474cdfa09aff91daa4b10ac4df28ffdaa649
Reviewed-on: https://go-review.googlesource.com/9741
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---

diff --git a/src/os/env.go b/src/os/env.go
index 4bc6dade44..a4ede15e61 100644
--- a/src/os/env.go
+++ b/src/os/env.go
@@ -81,6 +81,15 @@ func Getenv(key string) string {
 	return v
 }
 
+// LookupEnv retrieves the value of the environment variable named
+// by the key. If the variable is present in the environment the
+// value (which may be empty) is returned and the boolean is true.
+// Otherwise the returned value will be empty and the boolean will
+// be false.
+func LookupEnv(key string) (string, bool) {
+	return syscall.Getenv(key)
+}
+
 // Setenv sets the value of the environment variable named by the key.
 // It returns an error, if any.
 func Setenv(key, value string) error {
diff --git a/src/os/env_test.go b/src/os/env_test.go
index e618067513..622f39cfed 100644
--- a/src/os/env_test.go
+++ b/src/os/env_test.go
@@ -94,3 +94,15 @@ func TestUnsetenv(t *testing.T) {
 		t.Fatal("Unsetenv didn't clear TestUnsetenv")
 	}
 }
+
+func TestLookupEnv(t *testing.T) {
+	value, ok := LookupEnv("GOROOT") // Should be set.
+	if !ok {
+		t.Errorf("GOROOT is not set")
+	}
+	const v = "Variable That Does Not Exist"
+	value, ok = LookupEnv(v) // Should not be set.
+	if ok || value != "" {
+		t.Errorf("%s is set: %q", v, value)
+	}
+}