lint fixes

5 files changed, 75 insertions, 62 deletions

diff --git a/internal/contentenc/content.go b/internal/contentenc/content.go
index ac2e8de..dd3b77a 100644
--- a/internal/contentenc/content.go
+++ b/internal/contentenc/content.go
@@ -11,21 +11,28 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
+// NonceMode determines how nonces are created.
 type NonceMode int
 
 const (
-	// Default plaintext block size
+	// DefaultBS is the default plaintext block size
 	DefaultBS = 4096
+	// DefaultIVBits is the default length of IV, in bits.
 	// We always use 128-bit IVs for file content, but the
 	// key in the config file is encrypted with a 96-bit IV.
 	DefaultIVBits = 128
 
-	_                                   = iota // skip zero
-	RandomNonce               NonceMode = iota
+	_ = iota // skip zero
+	// RandomNonce chooses a random nonce.
+	RandomNonce NonceMode = iota
+	// ReverseDeterministicNonce chooses a deterministic nonce, suitable for
+	// use in reverse mode.
 	ReverseDeterministicNonce NonceMode = iota
-	ExternalNonce             NonceMode = iota
+	// ExternalNonce derives a nonce from external sources.
+	ExternalNonce NonceMode = iota
 )
 
+// ContentEnc is used to encipher and decipher file content.
 type ContentEnc struct {
 	// Cryptographic primitives
 	cryptoCore *cryptocore.CryptoCore
@@ -39,8 +46,8 @@ type ContentEnc struct {
 	allZeroNonce []byte
 }
 
+// New returns an initialized ContentEnc instance.
 func New(cc *cryptocore.CryptoCore, plainBS uint64) *ContentEnc {
-
 	cipherBS := plainBS + uint64(cc.IVLen) + cryptocore.AuthTagLen
 
 	return &ContentEnc{
@@ -62,16 +69,16 @@ func (be *ContentEnc) CipherBS() uint64 {
 	return be.cipherBS
 }
 
-// DecryptBlocks - Decrypt a number of blocks
+// DecryptBlocks decrypts a number of blocks
 // TODO refactor to three-param for
-func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, fileId []byte) ([]byte, error) {
+func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, fileID []byte) ([]byte, error) {
 	cBuf := bytes.NewBuffer(ciphertext)
 	var err error
 	var pBuf bytes.Buffer
 	for cBuf.Len() > 0 {
 		cBlock := cBuf.Next(int(be.cipherBS))
 		var pBlock []byte
-		pBlock, err = be.DecryptBlock(cBlock, firstBlockNo, fileId)
+		pBlock, err = be.DecryptBlock(cBlock, firstBlockNo, fileID)
 		if err != nil {
 			break
 		}
@@ -85,7 +92,7 @@ func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, file
 //
 // Corner case: A full-sized block of all-zero ciphertext bytes is translated
 // to an all-zero plaintext block, i.e. file hole passtrough.
-func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileId []byte) ([]byte, error) {
+func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileID []byte) ([]byte, error) {
 
 	// Empty block?
 	if len(ciphertext) == 0 {
@@ -114,7 +121,7 @@ func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileId []b
 	// Decrypt
 	var plaintext []byte
 	aData := make([]byte, 8)
-	aData = append(aData, fileId...)
+	aData = append(aData, fileID...)
 	binary.BigEndian.PutUint64(aData, blockNo)
 	plaintext, err := be.cryptoCore.AEADCipher.Open(plaintext, nonce, ciphertext, aData)
 
diff --git a/internal/contentenc/content_test.go b/internal/contentenc/content_test.go
index 70b71fe..e6c610c 100644
--- a/internal/contentenc/content_test.go
+++ b/internal/contentenc/content_test.go
@@ -63,7 +63,7 @@ func TestCiphertextRange(t *testing.T) {
 		if alignedLength < r.length {
 			t.Errorf("alignedLength=%d is smaller than length=%d", alignedLength, r.length)
 		}
-		if (alignedOffset-HEADER_LEN)%f.cipherBS != 0 {
+		if (alignedOffset-HeaderLen)%f.cipherBS != 0 {
 			t.Errorf("alignedOffset=%d is not aligned", alignedOffset)
 		}
 		if r.offset%f.plainBS != 0 && skipBytes == 0 {
@@ -81,7 +81,7 @@ func TestBlockNo(t *testing.T) {
 	if b != 0 {
 		t.Errorf("actual: %d", b)
 	}
-	b = f.CipherOffToBlockNo(HEADER_LEN + f.cipherBS)
+	b = f.CipherOffToBlockNo(HeaderLen + f.cipherBS)
 	if b != 1 {
 		t.Errorf("actual: %d", b)
 	}
diff --git a/internal/contentenc/file_header.go b/internal/contentenc/file_header.go
index 1463773..9ae5ae9 100644
--- a/internal/contentenc/file_header.go
+++ b/internal/contentenc/file_header.go
@@ -12,42 +12,44 @@ import (
 )
 
 const (
-	// Current On-Disk-Format version
+	// CurrentVersion is the current On-Disk-Format version
 	CurrentVersion = 2
 
-	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
+	headerVersionLen = 2  // uint16
+	headerIDLen      = 16 // 128 bit random file id
+	// HeaderLen is the total header length
+	HeaderLen = headerVersionLen + headerIDLen
 )
 
+// FileHeader represents the header stored on each non-empty file.
 type FileHeader struct {
 	Version uint16
-	Id      []byte
+	ID      []byte
 }
 
 // Pack - serialize fileHeader object
 func (h *FileHeader) Pack() []byte {
-	if len(h.Id) != HEADER_ID_LEN || h.Version != CurrentVersion {
+	if len(h.ID) != headerIDLen || h.Version != CurrentVersion {
 		panic("FileHeader object not properly initialized")
 	}
-	buf := make([]byte, HEADER_LEN)
-	binary.BigEndian.PutUint16(buf[0:HEADER_VERSION_LEN], h.Version)
-	copy(buf[HEADER_VERSION_LEN:], h.Id)
+	buf := make([]byte, HeaderLen)
+	binary.BigEndian.PutUint16(buf[0:headerVersionLen], h.Version)
+	copy(buf[headerVersionLen:], h.ID)
 	return buf
 
 }
 
 // ParseHeader - parse "buf" into fileHeader object
 func ParseHeader(buf []byte) (*FileHeader, error) {
-	if len(buf) != HEADER_LEN {
-		return nil, fmt.Errorf("ParseHeader: invalid length: got %d, want %d", len(buf), HEADER_LEN)
+	if len(buf) != HeaderLen {
+		return nil, fmt.Errorf("ParseHeader: invalid length: got %d, want %d", len(buf), HeaderLen)
 	}
 	var h FileHeader
-	h.Version = binary.BigEndian.Uint16(buf[0:HEADER_VERSION_LEN])
+	h.Version = binary.BigEndian.Uint16(buf[0:headerVersionLen])
 	if h.Version != CurrentVersion {
 		return nil, fmt.Errorf("ParseHeader: invalid version: got %d, want %d", h.Version, CurrentVersion)
 	}
-	h.Id = buf[HEADER_VERSION_LEN:]
+	h.ID = buf[headerVersionLen:]
 	return &h, nil
 }
 
@@ -55,6 +57,6 @@ func ParseHeader(buf []byte) (*FileHeader, error) {
 func RandomHeader() *FileHeader {
 	var h FileHeader
 	h.Version = CurrentVersion
-	h.Id = cryptocore.RandBytes(HEADER_ID_LEN)
+	h.ID = cryptocore.RandBytes(headerIDLen)
 	return &h
 }
diff --git a/internal/contentenc/intrablock.go b/internal/contentenc/intrablock.go
index 632e76b..3714e37 100644
--- a/internal/contentenc/intrablock.go
+++ b/internal/contentenc/intrablock.go
@@ -1,10 +1,10 @@
 package contentenc
 
-// intraBlock identifies a part of a file block
-type intraBlock struct {
-	// Block number in the file
+// IntraBlock identifies a part of a file block
+type IntraBlock struct {
+	// BlockNo is the block number in the file
 	BlockNo uint64
-	// Offset into block payload
+	// Skip is an offset into the block payload
 	// In forwared mode: block plaintext
 	// In reverse mode: offset into block ciphertext. Takes the header into
 	// account.
@@ -17,8 +17,8 @@ type intraBlock struct {
 	fs     *ContentEnc
 }
 
-// isPartial - is the block partial? This means we have to do read-modify-write.
-func (ib *intraBlock) IsPartial() bool {
+// IsPartial - is the block partial? This means we have to do read-modify-write.
+func (ib *IntraBlock) IsPartial() bool {
 	if ib.Skip > 0 || ib.Length < ib.fs.plainBS {
 		return true
 	}
@@ -26,17 +26,17 @@ func (ib *intraBlock) IsPartial() bool {
 }
 
 // BlockCipherOff returns the ciphertext offset corresponding to BlockNo
-func (ib *intraBlock) BlockCipherOff() (offset uint64) {
+func (ib *IntraBlock) BlockCipherOff() (offset uint64) {
 	return ib.fs.BlockNoToCipherOff(ib.BlockNo)
 }
 
 // BlockPlainOff returns the plaintext offset corresponding to BlockNo
-func (ib *intraBlock) BlockPlainOff() (offset uint64) {
+func (ib *IntraBlock) BlockPlainOff() (offset uint64) {
 	return ib.fs.BlockNoToPlainOff(ib.BlockNo)
 }
 
 // CropBlock - crop a potentially larger plaintext block down to the relevant part
-func (ib *intraBlock) CropBlock(d []byte) []byte {
+func (ib *IntraBlock) CropBlock(d []byte) []byte {
 	lenHave := len(d)
 	lenWant := int(ib.Skip + ib.Length)
 	if lenHave < lenWant {
@@ -45,8 +45,9 @@ 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) {
+// JointCiphertextRange is the 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]
 
@@ -57,8 +58,9 @@ func (ib *intraBlock) JointCiphertextRange(blocks []intraBlock) (offset uint64,
 	return offset, length
 }
 
-// Plaintext range corresponding to the sum of all "blocks" (complete blocks)
-func JointPlaintextRange(blocks []intraBlock) (offset uint64, length uint64) {
+// JointPlaintextRange is the plaintext range corresponding to the sum of all
+// "blocks" (complete blocks)
+func JointPlaintextRange(blocks []IntraBlock) (offset uint64, length uint64) {
 	firstBlock := blocks[0]
 	lastBlock := blocks[len(blocks)-1]
 
diff --git a/internal/contentenc/offsets.go b/internal/contentenc/offsets.go
index 61939a9..97d7116 100644
--- a/internal/contentenc/offsets.go
+++ b/internal/contentenc/offsets.go
@@ -8,43 +8,43 @@ import (
 
 // Contentenc methods that translate offsets between ciphertext and plaintext
 
-// get the block number at plain-text offset
+// PlainOffToBlockNo converts a plaintext offset to the ciphertext block number.
 func (be *ContentEnc) PlainOffToBlockNo(plainOffset uint64) uint64 {
 	return plainOffset / be.plainBS
 }
 
-// get the block number at cipher-text offset
+// CipherOffToBlockNo converts the ciphertext offset to the plaintext block number.
 func (be *ContentEnc) CipherOffToBlockNo(cipherOffset uint64) uint64 {
-	if cipherOffset < HEADER_LEN {
+	if cipherOffset < HeaderLen {
 		log.Panicf("BUG: offset %d is inside the file header", cipherOffset)
 	}
-	return (cipherOffset - HEADER_LEN) / be.cipherBS
+	return (cipherOffset - HeaderLen) / be.cipherBS
 }
 
-// get ciphertext offset of block "blockNo"
+// BlockNoToCipherOff gets the ciphertext offset of block "blockNo"
 func (be *ContentEnc) BlockNoToCipherOff(blockNo uint64) uint64 {
-	return HEADER_LEN + blockNo*be.cipherBS
+	return HeaderLen + blockNo*be.cipherBS
 }
 
-// get plaintext offset of block "blockNo"
+// BlockNoToPlainOff gets the plaintext offset of block "blockNo"
 func (be *ContentEnc) BlockNoToPlainOff(blockNo uint64) uint64 {
 	return blockNo * be.plainBS
 }
 
-// PlainSize - calculate plaintext size from ciphertext size
+// CipherSizeToPlainSize calculates the plaintext size from a ciphertext size
 func (be *ContentEnc) CipherSizeToPlainSize(cipherSize uint64) uint64 {
 	// Zero-sized files stay zero-sized
 	if cipherSize == 0 {
 		return 0
 	}
 
-	if cipherSize == HEADER_LEN {
+	if cipherSize == HeaderLen {
 		tlog.Warn.Printf("cipherSize %d == header size: interrupted write?\n", cipherSize)
 		return 0
 	}
 
-	if cipherSize < HEADER_LEN {
-		tlog.Warn.Printf("cipherSize %d < header size %d: corrupt file\n", cipherSize, HEADER_LEN)
+	if cipherSize < HeaderLen {
+		tlog.Warn.Printf("cipherSize %d < header size %d: corrupt file\n", cipherSize, HeaderLen)
 		return 0
 	}
 
@@ -52,12 +52,12 @@ func (be *ContentEnc) CipherSizeToPlainSize(cipherSize uint64) uint64 {
 	blockNo := be.CipherOffToBlockNo(cipherSize - 1)
 	blockCount := blockNo + 1
 
-	overhead := be.BlockOverhead()*blockCount + HEADER_LEN
+	overhead := be.BlockOverhead()*blockCount + HeaderLen
 
 	return cipherSize - overhead
 }
 
-// CipherSize - calculate ciphertext size from plaintext size
+// PlainSizeToCipherSize calculates the ciphertext size from a plaintext size
 func (be *ContentEnc) PlainSizeToCipherSize(plainSize uint64) uint64 {
 	// Zero-sized files stay zero-sized
 	if plainSize == 0 {
@@ -68,16 +68,16 @@ func (be *ContentEnc) PlainSizeToCipherSize(plainSize uint64) uint64 {
 	blockNo := be.PlainOffToBlockNo(plainSize - 1)
 	blockCount := blockNo + 1
 
-	overhead := be.BlockOverhead()*blockCount + HEADER_LEN
+	overhead := be.BlockOverhead()*blockCount + HeaderLen
 
 	return plainSize + overhead
 }
 
-// Split a plaintext byte range into (possibly partial) blocks
+// ExplodePlainRange splits a plaintext byte range into (possibly partial) blocks
 // Returns an empty slice if length == 0.
-func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []intraBlock {
-	var blocks []intraBlock
-	var nextBlock intraBlock
+func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []IntraBlock {
+	var blocks []IntraBlock
+	var nextBlock IntraBlock
 	nextBlock.fs = be
 
 	for length > 0 {
@@ -94,11 +94,11 @@ func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []intraBlo
 	return blocks
 }
 
-// Split a ciphertext byte range into (possibly partial) blocks
-// This is used in reverse mode when reading files
-func (be *ContentEnc) ExplodeCipherRange(offset uint64, length uint64) []intraBlock {
-	var blocks []intraBlock
-	var nextBlock intraBlock
+// ExplodeCipherRange splits a ciphertext byte range into (possibly partial)
+// blocks This is used in reverse mode when reading files
+func (be *ContentEnc) ExplodeCipherRange(offset uint64, length uint64) []IntraBlock {
+	var blocks []IntraBlock
+	var nextBlock IntraBlock
 	nextBlock.fs = be
 
 	for length > 0 {
@@ -120,10 +120,12 @@ func (be *ContentEnc) ExplodeCipherRange(offset uint64, length uint64) []intraBl
 	return blocks
 }
 
+// BlockOverhead returns the per-block overhead.
 func (be *ContentEnc) BlockOverhead() uint64 {
 	return be.cipherBS - be.plainBS
 }
 
+// MinUint64 returns the minimum of two uint64 values.
 func MinUint64(x uint64, y uint64) uint64 {
 	if x < y {
 		return x