From 649b89377e91ad6dbe710784f9e662082d31a1ff Mon Sep 17 00:00:00 2001
From: David Heuschmann <heuschmann.d@gmail.com>
Date: Tue, 20 Nov 2018 12:30:14 +0100
Subject: [PATCH] os: return an error from UserHomeDir to match UserCacheDir

UserHomeDir used to return an empty string if the corresponding
environment variable was not set. Changed it to return an error if the
variable is not set, to have the same signature and behaviour as UserCacheDir.

Fixes #28562

Change-Id: I42c497e8011ecfbbadebe7de1751575273be221c
Reviewed-on: https://go-review.googlesource.com/c/150418
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---
 src/crypto/x509/root_darwin.go |  6 +++---
 src/os/file.go                 | 18 ++++++++++--------
 src/os/os_test.go              |  9 ++++++---
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/crypto/x509/root_darwin.go b/src/crypto/x509/root_darwin.go
index ae69a2fadd..4a02c07596 100644
--- a/src/crypto/x509/root_darwin.go
+++ b/src/crypto/x509/root_darwin.go
@@ -66,10 +66,10 @@ func execSecurityRoots() (*CertPool, error) {
 		"/Library/Keychains/System.keychain",
 	}
 
-	home := os.UserHomeDir()
-	if home == "" {
+	home, err := os.UserHomeDir()
+	if err != nil {
 		if debugExecDarwinRoots {
-			println("crypto/x509: can't get user home directory")
+			println("crypto/x509: can't get user home directory: %v", err)
 		}
 	} else {
 		args = append(args,
diff --git a/src/os/file.go b/src/os/file.go
index d9c5c57c17..9b7863e9b6 100644
--- a/src/os/file.go
+++ b/src/os/file.go
@@ -386,22 +386,24 @@ func UserCacheDir() (string, error) {
 // On Unix, including macOS, it returns the $HOME environment variable.
 // On Windows, it returns %USERPROFILE%.
 // On Plan 9, it returns the $home environment variable.
-func UserHomeDir() string {
+func UserHomeDir() (string, error) {
+	env, enverr := "HOME", "$HOME"
 	switch runtime.GOOS {
 	case "windows":
-		return Getenv("USERPROFILE")
+		env, enverr = "USERPROFILE", "%userprofile%"
 	case "plan9":
-		return Getenv("home")
+		env, enverr = "home", "$home"
 	case "nacl", "android":
-		return "/"
+		return "/", nil
 	case "darwin":
 		if runtime.GOARCH == "arm" || runtime.GOARCH == "arm64" {
-			return "/"
+			return "/", nil
 		}
-		fallthrough
-	default:
-		return Getenv("HOME")
 	}
+	if v := Getenv(env); v != "" {
+		return v, nil
+	}
+	return "", errors.New(enverr + " is not defined")
 }
 
 // Chmod changes the mode of the named file to mode.
diff --git a/src/os/os_test.go b/src/os/os_test.go
index d838272215..9c4d5dada9 100644
--- a/src/os/os_test.go
+++ b/src/os/os_test.go
@@ -2300,9 +2300,12 @@ func TestDoubleCloseError(t *testing.T) {
 }
 
 func TestUserHomeDir(t *testing.T) {
-	dir := UserHomeDir()
-	if dir == "" {
-		t.Fatal("UserHomeDir returned an empty string")
+	dir, err := UserHomeDir()
+	if dir == "" && err == nil {
+		t.Fatal("UserHomeDir returned an empty string but no error")
+	}
+	if err != nil {
+		t.Skipf("UserHomeDir failed: %v", err)
 	}
 	fi, err := Stat(dir)
 	if err != nil {
-- 
2.48.1