From ff7fb5a5d696256b232f8435c53087d5b12848ab Mon Sep 17 00:00:00 2001
From: Evgeniy Karagodin <ekaragodin@gmail.com>
Date: Mon, 24 Jun 2019 22:08:06 +0700
Subject: [PATCH] Add userHomeDir (#521)

---
 os/README.md | 16 ++++++++++++++++
 os/mod.ts    | 26 ++++++++++++++++++++++++++
 os/test.ts   |  8 ++++++++
 test.ts      |  1 +
 4 files changed, 51 insertions(+)
 create mode 100644 os/README.md
 create mode 100644 os/mod.ts
 create mode 100644 os/test.ts

diff --git a/os/README.md b/os/README.md
new file mode 100644
index 000000000000..0f2ea810b4f5
--- /dev/null
+++ b/os/README.md
@@ -0,0 +1,16 @@
+# os
+
+Module provide platform-independent interface to operating system functionality.
+
+## Usage
+
+### userHomeDir
+
+Returns the current user's home directory. On Unix, including macOS, it returns the \$HOME environment variable. On Windows, it returns %USERPROFILE%.
+Needs permissions to access env (--allow-env).
+
+```ts
+import { userHomeDir } from "https://deno.land/std/os/mod.ts";
+
+userHomeDir();
+```
diff --git a/os/mod.ts b/os/mod.ts
new file mode 100644
index 000000000000..a2bb0457b61e
--- /dev/null
+++ b/os/mod.ts
@@ -0,0 +1,26 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/**
+ * Returns the current user's home directory.
+ * On Unix, including macOS, it returns the $HOME environment variable.
+ * On Windows, it returns %USERPROFILE%.
+ * Needs permissions to access env (--allow-env).
+ *
+ * Ported from Go: https://github.com/golang/go/blob/go1.12.5/src/os/file.go#L389
+ */
+export function userHomeDir(): string {
+  let env = "HOME";
+  let envErr = "$HOME";
+
+  if (Deno.platform.os === "win") {
+    env = "USERPROFILE";
+    envErr = "%USERPROFILE%";
+  }
+
+  const value = Deno.env()[env];
+  if (value !== "") {
+    return value;
+  }
+
+  throw new Error(`Environment variable '${envErr}' is not defined.`);
+}
diff --git a/os/test.ts b/os/test.ts
new file mode 100644
index 000000000000..f1993f22bafc
--- /dev/null
+++ b/os/test.ts
@@ -0,0 +1,8 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { test } from "../testing/mod.ts";
+import { assertNotEquals } from "../testing/asserts.ts";
+import { userHomeDir } from "./mod.ts";
+
+test(function testUserHomeDir(): void {
+  assertNotEquals(userHomeDir(), "");
+});
diff --git a/test.ts b/test.ts
index 5747be1c5e7b..1f41003f3d6f 100755
--- a/test.ts
+++ b/test.ts
@@ -23,6 +23,7 @@ import "./textproto/test.ts";
 import "./util/test.ts";
 import "./ws/test.ts";
 import "./encoding/test.ts";
+import "./os/test.ts";
 
 import { xrun } from "./prettier/util.ts";
 import { red, green } from "./colors/mod.ts";