Refactor ciphertext <-> plaintext offset translation functions

Move all the intelligence into the new file address_translation.go.
That the calculations were spread out too much became apparent when adding
the file header. This should make the code much easier to modify in the
future.

12 files changed, 158 insertions, 186 deletions

diff --git a/cryptfs/address_translation.go b/cryptfs/address_translation.go
new file mode 100644
index 0000000..dfc6ef9
--- /dev/null
+++ b/cryptfs/address_translation.go
@@ -0,0 +1,79 @@
+package cryptfs
+
+// CryptFS methods that translate offsets between ciphertext and plaintext
+
+// get the block number at plain-text offset
+func (be *CryptFS) PlainOffToBlockNo(plainOffset uint64) uint64 {
+	return plainOffset / be.plainBS
+}
+
+// get the block number at ciphter-text offset
+func (be *CryptFS) CipherOffToBlockNo(cipherOffset uint64) uint64 {
+	return (cipherOffset - HEADER_LEN) / be.cipherBS
+}
+
+// get ciphertext offset of block "blockNo"
+func (be *CryptFS) BlockNoToCipherOff(blockNo uint64) uint64 {
+	return HEADER_LEN + blockNo*be.cipherBS
+}
+
+// get plaintext offset of block "blockNo"
+func (be *CryptFS) BlockNoToPlainOff(blockNo uint64) uint64 {
+	return blockNo * be.plainBS
+}
+
+// PlainSize - calculate plaintext size from ciphertext size
+func (be *CryptFS) CipherSizeToPlainSize(cipherSize uint64) uint64 {
+
+	// Zero sized files stay zero-sized
+	if cipherSize == 0 {
+		return 0
+	}
+
+	// Block number at last byte
+	blockNo := be.CipherOffToBlockNo(cipherSize - 1)
+	blockCount := blockNo + 1
+
+	overhead := BLOCK_OVERHEAD*blockCount + HEADER_LEN
+
+	return cipherSize - overhead
+}
+
+// CipherSize - calculate ciphertext size from plaintext size
+func (be *CryptFS) PlainSizeToCipherSize(plainSize uint64) uint64 {
+
+	// Block number at last byte
+	blockNo := be.PlainOffToBlockNo(plainSize - 1)
+	blockCount := blockNo + 1
+
+	overhead := BLOCK_OVERHEAD*blockCount + HEADER_LEN
+
+	return plainSize + overhead
+}
+
+// Split a plaintext byte range into (possibly partial) blocks
+func (be *CryptFS) ExplodePlainRange(offset uint64, length uint64) []intraBlock {
+	var blocks []intraBlock
+	var nextBlock intraBlock
+	nextBlock.fs = be
+
+	for length > 0 {
+		nextBlock.BlockNo = be.PlainOffToBlockNo(offset)
+		nextBlock.Skip = offset - be.BlockNoToPlainOff(nextBlock.BlockNo)
+
+		// Minimum of remaining data and remaining space in the block
+		nextBlock.Length = MinUint64(length, be.plainBS-nextBlock.Skip)
+
+		blocks = append(blocks, nextBlock)
+		offset += nextBlock.Length
+		length -= nextBlock.Length
+	}
+	return blocks
+}
+
+func MinUint64(x uint64, y uint64) uint64 {
+	if x < y {
+		return x
+	}
+	return y
+}
diff --git a/cryptfs/config_file.go b/cryptfs/config_file.go
index 7e762ad..16a3eec 100644
--- a/cryptfs/config_file.go
+++ b/cryptfs/config_file.go
@@ -1,8 +1,8 @@
 package cryptfs
 
 import (
-	"fmt"
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 )
 import "os"
diff --git a/cryptfs/content_test.go b/cryptfs/content_test.go
index 4e1b447..37635f0 100644
--- a/cryptfs/content_test.go
+++ b/cryptfs/content_test.go
@@ -16,7 +16,7 @@ func TestSplitRange(t *testing.T) {
 		testRange{0, 10},
 		testRange{234, 6511},
 		testRange{65444, 54},
-		testRange{0, 1024*1024},
+		testRange{0, 1024 * 1024},
 		testRange{0, 65536},
 		testRange{6654, 8945})
 
@@ -24,8 +24,8 @@ func TestSplitRange(t *testing.T) {
 	f := NewCryptFS(key, true)
 
 	for _, r := range ranges {
-		parts := f.SplitRange(r.offset, r.length)
-		var lastBlockNo uint64 = 1<<63
+		parts := f.ExplodePlainRange(r.offset, r.length)
+		var lastBlockNo uint64 = 1 << 63
 		for _, p := range parts {
 			if p.BlockNo == lastBlockNo {
 				t.Errorf("Duplicate block number %d", p.BlockNo)
@@ -51,11 +51,15 @@ func TestCiphertextRange(t *testing.T) {
 	f := NewCryptFS(key, true)
 
 	for _, r := range ranges {
-		alignedOffset, alignedLength, skipBytes := f.CiphertextRange(r.offset, r.length)
+
+		blocks := f.ExplodePlainRange(r.offset, r.length)
+		alignedOffset, alignedLength := blocks[0].JointCiphertextRange(blocks)
+		skipBytes := blocks[0].Skip
+
 		if alignedLength < r.length {
 			t.Errorf("alignedLength=%s is smaller than length=%d", alignedLength, r.length)
 		}
-		if (alignedOffset - HEADER_LEN)%f.cipherBS != 0 {
+		if (alignedOffset-HEADER_LEN)%f.cipherBS != 0 {
 			t.Errorf("alignedOffset=%d is not aligned", alignedOffset)
 		}
 		if r.offset%f.plainBS != 0 && skipBytes == 0 {
@@ -68,19 +72,19 @@ func TestBlockNo(t *testing.T) {
 	key := make([]byte, KEY_LEN)
 	f := NewCryptFS(key, true)
 
-	b := f.BlockNoCipherOff(788)
+	b := f.CipherOffToBlockNo(788)
 	if b != 0 {
 		t.Errorf("actual: %d", b)
 	}
-	b = f.BlockNoCipherOff(HEADER_LEN + f.CipherBS())
+	b = f.CipherOffToBlockNo(HEADER_LEN + f.cipherBS)
 	if b != 1 {
 		t.Errorf("actual: %d", b)
 	}
-	b = f.BlockNoPlainOff(788)
+	b = f.PlainOffToBlockNo(788)
 	if b != 0 {
 		t.Errorf("actual: %d", b)
 	}
-	b = f.BlockNoPlainOff(f.PlainBS())
+	b = f.PlainOffToBlockNo(f.plainBS)
 	if b != 1 {
 		t.Errorf("actual: %d", b)
 	}
diff --git a/cryptfs/cryptfs.go b/cryptfs/cryptfs.go
index 0593214..9fe492d 100644
--- a/cryptfs/cryptfs.go
+++ b/cryptfs/cryptfs.go
@@ -13,7 +13,7 @@ const (
 	KEY_LEN         = 32 // AES-256
 	NONCE_LEN       = 12
 	AUTH_TAG_LEN    = 16
-	BLOCK_OVERHEAD = NONCE_LEN + AUTH_TAG_LEN
+	BLOCK_OVERHEAD  = NONCE_LEN + AUTH_TAG_LEN
 )
 
 type CryptFS struct {
@@ -61,8 +61,3 @@ func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
 func (be *CryptFS) PlainBS() uint64 {
 	return be.plainBS
 }
-
-// Get ciphertext block size
-func (be *CryptFS) CipherBS() uint64 {
-	return be.cipherBS
-}
diff --git a/cryptfs/cryptfs_content.go b/cryptfs/cryptfs_content.go
index 03253d3..d74570f 100644
--- a/cryptfs/cryptfs_content.go
+++ b/cryptfs/cryptfs_content.go
@@ -12,11 +12,6 @@ import (
 	"os"
 )
 
-const (
-	// A block of 4124 zero bytes has this md5
-	ZeroBlockMd5 = "64331af89bd15a987b39855338336237"
-)
-
 // md5sum - debug helper, return md5 hex string
 func md5sum(buf []byte) string {
 	rawHash := md5.Sum(buf)
@@ -110,106 +105,6 @@ func (be *CryptFS) EncryptBlock(plaintext []byte, blockNo uint64, fileId []byte)
 	return ciphertext
 }
 
-// Split a plaintext byte range into (possibly partial) blocks
-func (be *CryptFS) SplitRange(offset uint64, length uint64) []intraBlock {
-	var b intraBlock
-	var parts []intraBlock
-
-	b.fs = be
-
-	for length > 0 {
-		b.BlockNo = offset / be.plainBS
-		b.Skip = offset % be.plainBS
-		// Minimum of remaining data and remaining space in the block
-		b.Length = be.minu64(length, be.plainBS-b.Skip)
-		parts = append(parts, b)
-		offset += b.Length
-		length -= b.Length
-	}
-	return parts
-}
-
-// PlainSize - calculate plaintext size from ciphertext size
-func (be *CryptFS) PlainSize(size uint64) uint64 {
-
-	// Zero sized files stay zero-sized
-	if size == 0 {
-		return 0
-	}
-
-	// Account for header
-	size -= HEADER_LEN
-
-	overhead := be.cipherBS - be.plainBS
-	nBlocks := (size + be.cipherBS - 1) / be.cipherBS
-	if nBlocks*overhead > size {
-		Warn.Printf("PlainSize: Negative size, returning 0 instead\n")
-		return 0
-	}
-	size -= nBlocks * overhead
-
-	return size
-}
-
-// CipherSize - calculate ciphertext size from plaintext size
-func (be *CryptFS) CipherSize(size uint64) uint64 {
-	overhead := be.cipherBS - be.plainBS
-	nBlocks := (size + be.plainBS - 1) / be.plainBS
-	size += nBlocks * overhead
-
-	return size
-}
-
-func (be *CryptFS) minu64(x uint64, y uint64) uint64 {
-	if x < y {
-		return x
-	}
-	return y
-}
-
-// CiphertextRange - Get byte range in backing ciphertext corresponding
-// to plaintext range. Returns a range aligned to ciphertext blocks.
-func (be *CryptFS) CiphertextRange(offset uint64, length uint64) (alignedOffset uint64, alignedLength uint64, skipBytes int) {
-	// Decrypting the ciphertext will yield too many plaintext bytes. Skip this number
-	// of bytes from the front.
-	skip := offset % be.plainBS
-
-	firstBlockNo := offset / be.plainBS
-	lastBlockNo := (offset + length - 1) / be.plainBS
-
-	alignedOffset = HEADER_LEN + firstBlockNo * be.cipherBS
-	alignedLength = (lastBlockNo - firstBlockNo + 1) * be.cipherBS
-
-	skipBytes = int(skip)
-	return alignedOffset, alignedLength, skipBytes
-}
-
-// Get the byte range in the ciphertext corresponding to blocks
-// (full blocks!)
-func (be *CryptFS) JoinCiphertextRange(blocks []intraBlock) (uint64, uint64) {
-
-	offset, _ := blocks[0].CiphertextRange()
-	last := blocks[len(blocks)-1]
-	length := (last.BlockNo - blocks[0].BlockNo + 1) * be.cipherBS
-
-	return offset, length
-}
-
-// Crop plaintext that correspons to complete cipher blocks down to what is
-// requested according to "iblocks"
-func (be *CryptFS) CropPlaintext(plaintext []byte, blocks []intraBlock) []byte {
-	offset := blocks[0].Skip
-	last := blocks[len(blocks)-1]
-	length := (last.BlockNo - blocks[0].BlockNo + 1) * be.plainBS
-	var cropped []byte
-	if offset+length > uint64(len(plaintext)) {
-		cropped = plaintext[offset:]
-	} else {
-		cropped = plaintext[offset : offset+length]
-	}
-	return cropped
-}
-
 // MergeBlocks - Merge newData into oldData at offset
 // New block may be bigger than both newData and oldData
 func (be *CryptFS) MergeBlocks(oldData []byte, newData []byte, offset int) []byte {
@@ -230,13 +125,3 @@ 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 - HEADER_LEN) / be.cipherBS
-}
diff --git a/cryptfs/file_header.go b/cryptfs/file_header.go
index 3fd7266..e16cbab 100644
--- a/cryptfs/file_header.go
+++ b/cryptfs/file_header.go
@@ -10,15 +10,15 @@ import (
 )
 
 const (
-	HEADER_CURRENT_VERSION  = 1 // Current on-disk-format version
-	HEADER_VERSION_LEN = 2 // uint16
-	HEADER_ID_LEN = 16 // 128 bit random file id
-	HEADER_LEN = HEADER_VERSION_LEN + HEADER_ID_LEN // Total header length
+	HEADER_CURRENT_VERSION = 1                                  // Current on-disk-format version
+	HEADER_VERSION_LEN     = 2                                  // uint16
+	HEADER_ID_LEN          = 16                                 // 128 bit random file id
+	HEADER_LEN             = HEADER_VERSION_LEN + HEADER_ID_LEN // Total header length
 )
 
 type FileHeader struct {
 	Version uint16
-	Id []byte
+	Id      []byte
 }
 
 // Pack - serialize fileHeader object
diff --git a/cryptfs/intrablock.go b/cryptfs/intrablock.go
index c83976c..faff471 100644
--- a/cryptfs/intrablock.go
+++ b/cryptfs/intrablock.go
@@ -19,13 +19,13 @@ func (ib *intraBlock) IsPartial() bool {
 // CiphertextRange - get byte range in ciphertext file corresponding to BlockNo
 // (complete block)
 func (ib *intraBlock) CiphertextRange() (offset uint64, length uint64) {
-	return HEADER_LEN + ib.BlockNo * ib.fs.cipherBS, ib.fs.cipherBS
+	return ib.fs.BlockNoToCipherOff(ib.BlockNo), ib.fs.cipherBS
 }
 
 // PlaintextRange - get byte range in plaintext corresponding to BlockNo
 // (complete block)
 func (ib *intraBlock) PlaintextRange() (offset uint64, length uint64) {
-	return ib.BlockNo * ib.fs.plainBS, ib.fs.plainBS
+	return ib.fs.BlockNoToPlainOff(ib.BlockNo), ib.fs.plainBS
 }
 
 // CropBlock - crop a potentially larger plaintext block down to the relevant part
@@ -37,3 +37,15 @@ func (ib *intraBlock) CropBlock(d []byte) []byte {
 	}
 	return d[ib.Skip:lenWant]
 }
+
+// Ciphertext range corresponding to the sum of all "blocks" (complete blocks)
+func (ib *intraBlock) JointCiphertextRange(blocks []intraBlock) (offset uint64, length uint64) {
+	firstBlock := blocks[0]
+	lastBlock := blocks[len(blocks)-1]
+
+	offset = ib.fs.BlockNoToCipherOff(firstBlock.BlockNo)
+	offsetLast := ib.fs.BlockNoToCipherOff(lastBlock.BlockNo)
+	length = offsetLast + ib.fs.cipherBS - offset
+
+	return offset, length
+}
diff --git a/main_test.go b/main_test.go
index 287c792..9262e6f 100644
--- a/main_test.go
+++ b/main_test.go
@@ -1,8 +1,6 @@
 package main
 
 import (
-	"runtime"
-	"sync"
 	"bytes"
 	"crypto/md5"
 	"encoding/hex"
@@ -11,6 +9,8 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"runtime"
+	"sync"
 	"testing"
 )
 
@@ -121,7 +121,7 @@ func testWriteN(t *testing.T, fn string, n int) string {
 	}
 	file.Close()
 
-	verifySize(t, plainDir + fn, n)
+	verifySize(t, plainDir+fn, n)
 
 	bin := md5.Sum(d)
 	hashWant := hex.EncodeToString(bin[:])
@@ -244,12 +244,12 @@ func TestFileHoles(t *testing.T) {
 }
 
 func sContains(haystack []string, needle string) bool {
-    for _, element := range haystack {
-        if element == needle {
-            return true
-        }
-    }
-    return false
+	for _, element := range haystack {
+		if element == needle {
+			return true
+		}
+	}
+	return false
 }
 
 func TestRmwRace(t *testing.T) {
@@ -313,10 +313,10 @@ func TestRmwRace(t *testing.T) {
 		goodMd5[m] = goodMd5[m] + 1
 
 		/*
-		if m == "6c1660fdabccd448d1359f27b3db3c99" {
-			fmt.Println(hex.Dump(buf))
-			t.FailNow()
-		}
+			if m == "6c1660fdabccd448d1359f27b3db3c99" {
+				fmt.Println(hex.Dump(buf))
+				t.FailNow()
+			}
 		*/
 	}
 	fmt.Println(goodMd5)
diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go
index 438fe77..e8d7003 100644
--- a/pathfs_frontend/file.go
+++ b/pathfs_frontend/file.go
@@ -128,8 +128,10 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
 	}
 
 	// Read the backing ciphertext in one go
-	alignedOffset, alignedLength, skip := f.cfs.CiphertextRange(off, length)
-	cryptfs.Debug.Printf("CiphertextRange(%d, %d) -> %d, %d, %d\n", off, length, alignedOffset, alignedLength, skip)
+	blocks := f.cfs.ExplodePlainRange(off, length)
+	alignedOffset, alignedLength := blocks[0].JointCiphertextRange(blocks)
+	skip := blocks[0].Skip
+	cryptfs.Debug.Printf("JointCiphertextRange(%d, %d) -> %d, %d, %d\n", off, length, alignedOffset, alignedLength, skip)
 	ciphertext := make([]byte, int(alignedLength))
 	f.fdLock.Lock()
 	n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
@@ -141,27 +143,27 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
 	// Truncate ciphertext buffer down to actually read bytes
 	ciphertext = ciphertext[0:n]
 
-	blockNo := (alignedOffset - cryptfs.HEADER_LEN) / f.cfs.CipherBS()
-	cryptfs.Debug.Printf("ReadAt offset=%d bytes (%d blocks), want=%d, got=%d\n", alignedOffset, blockNo, alignedLength, n)
+	firstBlockNo := blocks[0].BlockNo
+	cryptfs.Debug.Printf("ReadAt offset=%d bytes (%d blocks), want=%d, got=%d\n", alignedOffset, firstBlockNo, alignedLength, n)
 
 	// Decrypt it
-	plaintext, err := f.cfs.DecryptBlocks(ciphertext, blockNo, f.header.Id)
+	plaintext, err := f.cfs.DecryptBlocks(ciphertext, firstBlockNo, f.header.Id)
 	if err != nil {
-		blockNo := (alignedOffset + uint64(len(plaintext))) / f.cfs.PlainBS()
-		cipherOff := cryptfs.HEADER_LEN + blockNo * f.cfs.CipherBS()
-		plainOff := blockNo * f.cfs.PlainBS()
-		cryptfs.Warn.Printf("ino%d: doRead: corrupt block #%d (plainOff=%d/%d, cipherOff=%d/%d)\n",
-			f.ino, blockNo, plainOff, f.cfs.PlainBS(), cipherOff, f.cfs.CipherBS())
+		curruptBlockNo := firstBlockNo + f.cfs.PlainOffToBlockNo(uint64(len(plaintext)))
+		cipherOff := f.cfs.BlockNoToCipherOff(curruptBlockNo)
+		plainOff := f.cfs.BlockNoToPlainOff(curruptBlockNo)
+		cryptfs.Warn.Printf("ino%d: doRead: corrupt block #%d (plainOff=%d, cipherOff=%d)\n",
+			f.ino, curruptBlockNo, plainOff, cipherOff)
 		return nil, fuse.EIO
 	}
 
 	// Crop down to the relevant part
 	var out []byte
 	lenHave := len(plaintext)
-	lenWant := skip + int(length)
+	lenWant := int(skip + length)
 	if lenHave > lenWant {
-		out = plaintext[skip : skip+int(length)]
-	} else if lenHave > skip {
+		out = plaintext[skip:lenWant]
+	} else if lenHave > int(skip) {
 		out = plaintext[skip:lenHave]
 	}
 	// else: out stays empty, file was smaller than the requested offset
@@ -216,7 +218,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 	var written uint32
 	status := fuse.OK
 	dataBuf := bytes.NewBuffer(data)
-	blocks := f.cfs.SplitRange(uint64(off), uint64(len(data)))
+	blocks := f.cfs.ExplodePlainRange(uint64(off), uint64(len(data)))
 	for _, b := range blocks {
 
 		blockData := dataBuf.Next(int(b.Length))
@@ -239,11 +241,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 		blockOffset, _ := b.CiphertextRange()
 		blockData = f.cfs.EncryptBlock(blockData, b.BlockNo, f.header.Id)
 		cryptfs.Debug.Printf("ino%d: Writing %d bytes to block #%d, md5=%s\n",
-			f.ino, len(blockData) - cryptfs.BLOCK_OVERHEAD, b.BlockNo, cryptfs.Debug.Md5sum(blockData))
-		if len(blockData) != int(f.cfs.CipherBS()) {
-			cryptfs.Debug.Printf("ino%d: Writing partial block #%d (%d bytes)\n",
-				f.ino, b.BlockNo, len(blockData) - cryptfs.BLOCK_OVERHEAD)
-		}
+			f.ino, len(blockData)-cryptfs.BLOCK_OVERHEAD, b.BlockNo, cryptfs.Debug.Md5sum(blockData))
 		f.fdLock.Lock()
 		_, err := f.fd.WriteAt(blockData, int64(blockOffset))
 		f.fdLock.Unlock()
@@ -267,7 +265,7 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
 		cryptfs.Warn.Printf("Write: Fstat failed: %v\n", err)
 		return 0, fuse.ToStatus(err)
 	}
-	plainSize := f.cfs.PlainSize(uint64(fi.Size()))
+	plainSize := f.cfs.CipherSizeToPlainSize(uint64(fi.Size()))
 	if f.createsHole(plainSize, off) {
 		status := f.zeroPad(plainSize)
 		if status != fuse.OK {
@@ -332,7 +330,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 		cryptfs.Warn.Printf("Truncate: Fstat failed: %v\n", err)
 		return fuse.ToStatus(err)
 	}
-	oldSize := f.cfs.PlainSize(uint64(fi.Size()))
+	oldSize := f.cfs.CipherSizeToPlainSize(uint64(fi.Size()))
 	{
 		oldB := float32(oldSize) / float32(f.cfs.PlainBS())
 		newB := float32(newSize) / float32(f.cfs.PlainBS())
@@ -350,7 +348,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 			}
 		}
 
-		blocks := f.cfs.SplitRange(oldSize, newSize-oldSize)
+		blocks := f.cfs.ExplodePlainRange(oldSize, newSize-oldSize)
 		for _, b := range blocks {
 			// First and last block may be partial
 			if b.IsPartial() {
@@ -374,9 +372,9 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 		return fuse.OK
 	} else {
 		// File shrinks
-		blockNo := f.cfs.BlockNoPlainOff(newSize)
-		cipherOff := cryptfs.HEADER_LEN + blockNo * f.cfs.CipherBS()
-		plainOff := blockNo * f.cfs.PlainBS()
+		blockNo := f.cfs.PlainOffToBlockNo(newSize)
+		cipherOff := f.cfs.BlockNoToCipherOff(blockNo)
+		plainOff := f.cfs.BlockNoToPlainOff(blockNo)
 		lastBlockLen := newSize - plainOff
 		var data []byte
 		if lastBlockLen > 0 {
@@ -430,7 +428,7 @@ func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
 		return fuse.ToStatus(err)
 	}
 	a.FromStat(&st)
-	a.Size = f.cfs.PlainSize(a.Size)
+	a.Size = f.cfs.CipherSizeToPlainSize(a.Size)
 
 	return fuse.OK
 }
diff --git a/pathfs_frontend/file_holes.go b/pathfs_frontend/file_holes.go
index f906aa6..3db4828 100644
--- a/pathfs_frontend/file_holes.go
+++ b/pathfs_frontend/file_holes.go
@@ -7,8 +7,8 @@ import (
 
 // Will a write to offset "off" create a file hole?
 func (f *file) createsHole(plainSize uint64, off int64) bool {
-	nextBlock := f.cfs.BlockNoPlainOff(plainSize)
-	targetBlock := f.cfs.BlockNoPlainOff(uint64(off))
+	nextBlock := f.cfs.PlainOffToBlockNo(plainSize)
+	targetBlock := f.cfs.PlainOffToBlockNo(uint64(off))
 	if targetBlock > nextBlock {
 		return true
 	}
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index eebc87b..3ec503f 100644
--- a/pathfs_frontend/fs.go
+++ b/pathfs_frontend/fs.go
@@ -41,7 +41,7 @@ func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Stat
 		return a, status
 	}
 	if a.IsRegular() {
-		a.Size = fs.PlainSize(a.Size)
+		a.Size = fs.CipherSizeToPlainSize(a.Size)
 	} else if a.IsSymlink() {
 		target, _ := fs.Readlink(name, context)
 		a.Size = uint64(len(target))
diff --git a/test.bash b/test.bash
index fb849c4..976bb02 100755
--- a/test.bash
+++ b/test.bash
@@ -2,11 +2,10 @@
 
 set -eux
 
-cd cryptfs
-go build
-go test
-cd ..
+for i in ./cryptfs .
+do
 
-go build
-go test
+	go build $i
+	go test $i
+done