tests: respect TMPDIR if set

Setting TMPDIR now allows to run the tests against
a directory of your choice, making it easier to test
different filesystems.

test.bash

@@ -1,10 +1,16 @@
 #!/bin/bash
 
+if [[ -z $TMPDIR ]]; then
+	TMPDIR=/tmp
+else
+	echo "Using TMPDIR=$TMPDIR"
+fi
+
 set -eu
 
 cd "$(dirname "$0")"
 MYNAME=$(basename "$0")
-TESTDIR=/tmp/gocryptfs-test-parent
+TESTDIR=$TMPDIR/gocryptfs-test-parent
 mkdir -p $TESTDIR
 LOCKFILE=$TESTDIR/$MYNAME.lock
 

tests/test_helpers/helpers.go

@@ -21,8 +21,9 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/nametransform"
 )
 
-// TmpDir will be created inside this directory
-var testParentDir = "/tmp/gocryptfs-test-parent"
+// TmpDir will be created inside this directory, set in init() to
+// $TMPDIR/gocryptfs-test-parent .
+var testParentDir = ""
 
 // GocryptfsBinary is the assumed path to the gocryptfs build.
 const GocryptfsBinary = "../../gocryptfs"
@@ -43,11 +44,11 @@ var DefaultPlainDir string
 // DefaultCipherDir is TmpDir + "/default-cipher"
 var DefaultCipherDir string
 
-// SwitchTestParentDir changes testParentDir. This is used when you want
-// to perform tests on a special filesystem. For example, the xattr tests
-// cannot run on tmpfs and use /var/tmp instead of /tmp.
-func SwitchTestParentDir(newDir string) {
-	testParentDir = newDir
+// SwitchTMPDIR changes TMPDIR and hence the directory the test are performed in.
+// This is used when you want to perform tests on a special filesystem. The
+// xattr tests cannot run on tmpfs and use /var/tmp instead of /tmp.
+func SwitchTMPDIR(newDir string) {
+	os.Setenv("TMPDIR", newDir)
 	doInit()
 }
 
@@ -58,6 +59,7 @@ func init() {
 func doInit() {
 	X255 = string(bytes.Repeat([]byte("X"), 255))
 
+	testParentDir := os.TempDir() + "/gocryptfs-test-parent"
 	os.MkdirAll(testParentDir, 0700)
 	var err error
 	TmpDir, err = ioutil.TempDir(testParentDir, "")

tests/xattr/xattr_integration_test.go

@@ -16,16 +16,15 @@ import (
 	"github.com/rfjakob/gocryptfs/tests/test_helpers"
 )
 
-// On modern Linux distributions, /tmp may be on tmpfs,
-// which does not support user xattrs. Try /var/tmp instead.
-var alternateTestParentDir = "/var/tmp/gocryptfs-xattr-test-parent"
-
 func TestMain(m *testing.M) {
-	if !xattrSupported(test_helpers.TmpDir) {
-		test_helpers.SwitchTestParentDir(alternateTestParentDir)
+	// On modern Linux distributions, /tmp may be on tmpfs,
+	// which does not support user xattrs. Try /var/tmp instead
+	if !xattrSupported(test_helpers.TmpDir) && os.TempDir() == "/tmp" {
+		fmt.Printf("Switching from /tmp to /var/tmp for xattr tests\n")
+		test_helpers.SwitchTMPDIR("/var/tmp")
 	}
 	if !xattrSupported(test_helpers.TmpDir) {
-		fmt.Printf("xattrs not supported on %q", test_helpers.TmpDir)
+		fmt.Printf("xattrs not supported on %q\n", test_helpers.TmpDir)
 		os.Exit(1)
 	}
 	test_helpers.ResetTmpDir(true)