From 6e9edd53b30f0743d7558b0e6011fccdd08cf688 Mon Sep 17 00:00:00 2001
From: Mahmood Ali <mahmood@hashicorp.com>
Date: Wed, 30 Sep 2020 09:58:22 -0400
Subject: [PATCH] tests: failover to copying when symlinking fails

Symlinking busybox may fail when the test code and the test temporary
directory live on different volumes/partitions; so we should copy
instead.  This situation arises in the Vagrant setup, where the code
repository live on special file sharing volume.

Somewhat unrelated, remove `f.Sync()` invocation from a test copyFile
helper function.  Sync is useful only for crash recovery, and isn't
necessary in our test setup.  The sync invocation is a significant
overhead as it requires the OS to flush any cached writes to disk.
---
 drivers/java/driver_test.go              |  3 ---
 drivers/shared/executor/executor_test.go | 24 +++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/java/driver_test.go b/drivers/java/driver_test.go
index b4c2c9e40..f54d8c6da 100644
--- a/drivers/java/driver_test.go
+++ b/drivers/java/driver_test.go
@@ -332,9 +332,6 @@ func copyFile(src, dst string, t *testing.T) {
 	if _, err = io.Copy(out, in); err != nil {
 		t.Fatalf("copying %v -> %v failed: %v", src, dst, err)
 	}
-	if err := out.Sync(); err != nil {
-		t.Fatalf("copying %v -> %v failed: %v", src, dst, err)
-	}
 }
 
 func TestConfig_ParseAllHCL(t *testing.T) {
diff --git a/drivers/shared/executor/executor_test.go b/drivers/shared/executor/executor_test.go
index 41b141762..200fb323e 100644
--- a/drivers/shared/executor/executor_test.go
+++ b/drivers/shared/executor/executor_test.go
@@ -482,7 +482,29 @@ func setupRootfsBinary(t *testing.T, rootfs, path string) {
 	)
 
 	err = os.Link(src, dst)
-	require.NoError(t, err)
+	if err != nil {
+		// On failure, fallback to copying the file directly.
+		// Linking may fail if the test source code lives on a separate
+		// volume/partition from the temp dir used for testing
+		copyFile(t, src, dst)
+	}
+}
+
+func copyFile(t *testing.T, src, dst string) {
+	in, err := os.Open(src)
+	require.NoErrorf(t, err, "copying %v -> %v", src, dst)
+	defer in.Close()
+
+	out, err := os.Create(dst)
+	require.NoErrorf(t, err, "copying %v -> %v", src, dst)
+	defer func() {
+		if err := out.Close(); err != nil {
+			t.Fatalf("copying %v -> %v failed: %v", src, dst, err)
+		}
+	}()
+
+	_, err = io.Copy(out, in)
+	require.NoErrorf(t, err, "copying %v -> %v", src, dst)
 }
 
 // TestExecutor_Start_Kill_Immediately_NoGrace asserts that executors shutdown