macos: make testing without openssl work properly

On MacOS, building and testing without openssl is much easier.
The tests should skip tests that fail because of missing openssl
instead of aborting.

Fixes #123

internal/contentenc/content_test.go

@@ -23,7 +23,7 @@ func TestSplitRange(t *testing.T) {
 		testRange{6654, 8945})
 
 	key := make([]byte, cryptocore.KeyLen)
-	cc := cryptocore.New(key, cryptocore.BackendOpenSSL, DefaultIVBits, true, false)
+	cc := cryptocore.New(key, cryptocore.BackendGoGCM, DefaultIVBits, true, false)
 	f := New(cc, DefaultBS, false)
 
 	for _, r := range ranges {
@@ -51,7 +51,7 @@ func TestCiphertextRange(t *testing.T) {
 		testRange{6654, 8945})
 
 	key := make([]byte, cryptocore.KeyLen)
-	cc := cryptocore.New(key, cryptocore.BackendOpenSSL, DefaultIVBits, true, false)
+	cc := cryptocore.New(key, cryptocore.BackendGoGCM, DefaultIVBits, true, false)
 	f := New(cc, DefaultBS, false)
 
 	for _, r := range ranges {
@@ -74,7 +74,7 @@ func TestCiphertextRange(t *testing.T) {
 
 func TestBlockNo(t *testing.T) {
 	key := make([]byte, cryptocore.KeyLen)
-	cc := cryptocore.New(key, cryptocore.BackendOpenSSL, DefaultIVBits, true, false)
+	cc := cryptocore.New(key, cryptocore.BackendGoGCM, DefaultIVBits, true, false)
 	f := New(cc, DefaultBS, false)
 
 	b := f.CipherOffToBlockNo(788)

internal/cryptocore/cryptocore_test.go

@@ -2,24 +2,29 @@ package cryptocore
 
 import (
 	"testing"
+
+	"github.com/rfjakob/gocryptfs/internal/stupidgcm"
 )
 
 // "New" should accept at least these param combinations
 func TestCryptoCoreNew(t *testing.T) {
 	key := make([]byte, 32)
 	for _, useHKDF := range []bool{true, false} {
-		c := New(key, BackendOpenSSL, 128, useHKDF, false)
-		if c.IVLen != 16 {
-			t.Fail()
-		}
-		c = New(key, BackendGoGCM, 96, useHKDF, false)
+		c := New(key, BackendGoGCM, 96, useHKDF, false)
 		if c.IVLen != 12 {
 			t.Fail()
 		}
 		c = New(key, BackendGoGCM, 128, useHKDF, false)
 		if c.IVLen != 16 {
 			t.Fail()
 		}
+		if stupidgcm.BuiltWithoutOpenssl {
+			continue
+		}
+		c = New(key, BackendOpenSSL, 128, useHKDF, false)
+		if c.IVLen != 16 {
+			t.Fail()
+		}
 	}
 }
 

internal/stupidgcm/stupidgcm_test.go

@@ -1,3 +1,5 @@
+// +build !without_openssl
+
 // We compare against Go's built-in GCM implementation. Since stupidgcm only
 // supports 128-bit IVs and Go only supports that from 1.5 onward, we cannot
 // run these tests on older Go versions.