From 1400d20bb9409981e9d505457c4fceb2ab92d9b0 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Thu, 27 Jun 2013 22:14:23 -0400
Subject: [PATCH] builder/virtualbox: Error if output directory already exists

---
 builder/virtualbox/builder.go      |  4 ++++
 builder/virtualbox/builder_test.go | 25 +++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/builder/virtualbox/builder.go b/builder/virtualbox/builder.go
index 69ff257e8..4bbc04b1e 100644
--- a/builder/virtualbox/builder.go
+++ b/builder/virtualbox/builder.go
@@ -164,6 +164,10 @@ func (b *Builder) Prepare(raws ...interface{}) error {
 		}
 	}
 
+	if _, err := os.Stat(b.config.OutputDir); err == nil {
+		errs = append(errs, errors.New("Output directory already exists. It must not exist."))
+	}
+
 	if b.config.RawBootWait != "" {
 		b.config.BootWait, err = time.ParseDuration(b.config.RawBootWait)
 		if err != nil {
diff --git a/builder/virtualbox/builder_test.go b/builder/virtualbox/builder_test.go
index 46163c44f..e509cbcc9 100644
--- a/builder/virtualbox/builder_test.go
+++ b/builder/virtualbox/builder_test.go
@@ -224,6 +224,31 @@ func TestBuilderPrepare_ISOUrl(t *testing.T) {
 	}
 }
 
+func TestBuilderPrepare_OutputDir(t *testing.T) {
+	var b Builder
+	config := testConfig()
+
+	// Test with existing dir
+	dir, err := ioutil.TempDir("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(dir)
+
+	config["output_directory"] = dir
+	err = b.Prepare(config)
+	if err == nil {
+		t.Fatal("should have error")
+	}
+
+	// Test with a good one
+	config["output_directory"] = "i-hope-i-dont-exist"
+	err = b.Prepare(config)
+	if err != nil {
+		t.Fatalf("should not have error: %s", err)
+	}
+}
+
 func TestBuilderPrepare_ShutdownTimeout(t *testing.T) {
 	var b Builder
 	config := testConfig()