From 5229b8f5f5ef8d3e91fe2ab1f415131337161577 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher <jakobunt@gmail.com>
Date: Sun, 4 Oct 2015 11:03:40 +0200
Subject: [PATCH] Add BlockNoPlainOff() and BlockNoCipherOff() + test

Also, fix key, it is now []byte, not [16]byte
---
 cryptfs/content_test.go    | 26 ++++++++++++++++++++++++--
 cryptfs/cryptfs_content.go | 10 ++++++++++
 cryptfs/names_test.go      |  6 ++++--
 3 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/cryptfs/content_test.go b/cryptfs/content_test.go
index b53eeeb..8fd33c6 100644
--- a/cryptfs/content_test.go
+++ b/cryptfs/content_test.go
@@ -19,7 +19,7 @@ func TestSplitRange(t *testing.T) {
 		testRange{65444, 54},
 		testRange{6654, 8945})
 
-	var key [16]byte
+	key := make([]byte, 16)
 	f := NewCryptFS(key, true)
 
 	for _, r := range(ranges) {
@@ -42,7 +42,7 @@ func TestCiphertextRange(t *testing.T) {
 		testRange{65444, 54},
 		testRange{6654, 8945})
 
-	var key [16]byte
+	key := make([]byte, 16)
 	f := NewCryptFS(key, true)
 
 	for _, r := range(ranges) {
@@ -58,3 +58,25 @@ func TestCiphertextRange(t *testing.T) {
 		}
 	}
 }
+
+func TestBlockNo(t *testing.T) {
+	key := make([]byte, 16)
+	f := NewCryptFS(key, true)
+
+	b := f.BlockNoCipherOff(788)
+	if b != 0 {
+		t.Errorf("actual: %d", b)
+	}
+	b = f.BlockNoCipherOff(f.CipherBS())
+	if b != 1 {
+		t.Errorf("actual: %d", b)
+	}
+	b = f.BlockNoPlainOff(788)
+	if b != 0 {
+		t.Errorf("actual: %d", b)
+	}
+	b = f.BlockNoPlainOff(f.PlainBS())
+	if b != 1 {
+		t.Errorf("actual: %d", b)
+	}
+}
diff --git a/cryptfs/cryptfs_content.go b/cryptfs/cryptfs_content.go
index a903e02..ab5ec78 100644
--- a/cryptfs/cryptfs_content.go
+++ b/cryptfs/cryptfs_content.go
@@ -219,3 +219,13 @@ func (be *CryptFS) MergeBlocks(oldData []byte, newData []byte, offset int) []byt
 	}
 	return out[0:outLen]
 }
+
+// Get the block number at plain-text offset
+func (be *CryptFS) BlockNoPlainOff(plainOffset uint64) uint64 {
+		return plainOffset / be.plainBS
+}
+
+// Get the block number at ciphter-text offset
+func (be *CryptFS) BlockNoCipherOff(cipherOffset uint64) uint64 {
+		return cipherOffset / be.cipherBS
+}
diff --git a/cryptfs/names_test.go b/cryptfs/names_test.go
index 30ecfb9..7e20690 100644
--- a/cryptfs/names_test.go
+++ b/cryptfs/names_test.go
@@ -11,7 +11,7 @@ func TestTranslatePath(t *testing.T) {
 	s = append(s, "foo12312312312312312313123123123")
 	s = append(s, "123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890")
 
-	var key [16]byte
+	key := make([]byte, 16)
 	fs := NewCryptFS(key, true)
 
 	for _, n := range(s) {
@@ -32,8 +32,10 @@ func TestPad16(t *testing.T) {
 	s = append(s, []byte("foo"))
 	s = append(s, []byte("12345678901234567"))
 	s = append(s, []byte("12345678901234567abcdefg"))
-	var key [16]byte
+
+	key := make([]byte, 16)
 	fs := NewCryptFS(key, true)
+
 	for i := range(s) {
 		orig := s[i]
 		padded := fs.pad16(orig)