algo/common/dispatch.go

@@ -18,6 +18,7 @@ func RegisterDecoder(ext string, noop bool, dispatchFunc NewDecoderFunc) {
 	DecoderRegistry[ext] = append(DecoderRegistry[ext],
 		decoderItem{noop: noop, decoder: dispatchFunc})
 }
+
 func GetDecoder(filename string, skipNoop bool) (rs []NewDecoderFunc) {
 	ext := strings.ToLower(strings.TrimLeft(filepath.Ext(filename), "."))
 	for _, dec := range DecoderRegistry[ext] {

algo/common/sniff.go

@@ -35,15 +35,19 @@ func SnifferOGG(header []byte) bool {
 func SnifferFLAC(header []byte) bool {
 	return bytes.HasPrefix(header, []byte("fLaC"))
 }
+
 func SnifferMP3(header []byte) bool {
 	return bytes.HasPrefix(header, []byte("ID3"))
 }
+
 func SnifferWAV(header []byte) bool {
 	return bytes.HasPrefix(header, []byte("RIFF"))
 }
+
 func SnifferWMA(header []byte) bool {
 	return bytes.HasPrefix(header, []byte("\x30\x26\xb2\x75\x8e\x66\xcf\x11\xa6\xd9\x00\xaa\x00\x62\xce\x6c"))
 }
+
 func SnifferAAC(header []byte) bool {
 	return bytes.HasPrefix(header, []byte{0xFF, 0xF1})
 }

algo/kgm/kgm.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
+
 	"github.com/unlock-music/cli/algo/common"
 	"github.com/unlock-music/cli/internal/logging"
 )
@@ -59,6 +60,7 @@ func (d *Decoder) Validate() error {
 	d.key = d.file[0x1c:0x2c]
 	d.key = append(d.key, 0x00)
 	_ = d.file[0x2c:0x3c] //todo: key2
+
 	return nil
 }
 
@@ -67,6 +69,7 @@ func (d *Decoder) Decode() error {
 	dataEncrypted := d.file[headerLen:]
 	lenData := len(dataEncrypted)
 	initMask()
+
 	if fullMaskLen < lenData {
 		logging.Log().Warn("The file is too large and the processed audio is incomplete, " +
 			"please report to us about this file at https://github.com/unlock-music/cli/issues")
@@ -78,13 +81,16 @@ func (d *Decoder) Decode() error {
 		med8 := dataEncrypted[i] ^ d.key[i%17] ^ maskV2PreDef[i%(16*17)] ^ maskV2[i>>4]
 		d.audio[i] = med8 ^ (med8&0xf)<<4
 	}
+
 	if d.isVpr {
 		for i := 0; i < lenData; i++ {
 			d.audio[i] ^= maskDiffVpr[i%17]
 		}
 	}
+
 	return nil
 }
+
 func init() {
 	// Kugou
 	common.RegisterDecoder("kgm", false, NewDecoder)

algo/kgm/mask.go

@@ -3,10 +3,11 @@ package kgm
 import (
 	"bytes"
 	_ "embed"
+	"io"
+
 	"github.com/ulikunitz/xz"
 	"github.com/unlock-music/cli/internal/logging"
 	"go.uber.org/zap"
-	"io"
 )
 
 var maskDiffVpr = []byte{
@@ -41,7 +42,7 @@ var maskV2 []byte
 var fullMaskLen int
 var initMaskOK = false
 
-//todo: decompress mask on demand
+// TODO: decompress mask on demand
 func initMask() {
 	if initMaskOK {
 		return

algo/kwm/kwm.go

@@ -4,10 +4,11 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
-	"github.com/unlock-music/cli/algo/common"
 	"strconv"
 	"strings"
 	"unicode"
+
+	"github.com/unlock-music/cli/algo/common"
 )
 
 var (
@@ -57,6 +58,7 @@ func (d *Decoder) Validate() error {
 	if lenData < 1024 {
 		return ErrKwFileSize
 	}
+
 	if !bytes.Equal(magicHeader, d.file[:16]) {
 		return ErrKwMagicHeader
 	}
@@ -69,9 +71,11 @@ func generateMask(key []byte) []byte {
 	keyStr := strconv.FormatUint(keyInt, 10)
 	keyStrTrim := padOrTruncate(keyStr, 32)
 	mask := make([]byte, 32)
+
 	for i := 0; i < 32; i++ {
 		mask[i] = keyPreDefined[i] ^ keyStrTrim[i]
 	}
+
 	return mask
 }
 
@@ -83,13 +87,13 @@ func (d *Decoder) parseBitrateAndType() {
 			break
 		}
 	}
+
 	var err error
 	d.bitrate, err = strconv.Atoi(bitType[:charPos])
 	if err != nil {
 		d.bitrate = 0
 	}
 	d.outputExt = strings.ToLower(bitType[charPos:])
-
 }
 
 func (d *Decoder) Decode() error {
@@ -102,6 +106,7 @@ func (d *Decoder) Decode() error {
 	for i := 0; i < dataLen; i++ {
 		d.audio[i] ^= d.mask[i&0x1F] //equals: [i % 32]
 	}
+
 	return nil
 }
 

algo/ncm/meta.go

@@ -1,8 +1,9 @@
 package ncm
 
 import (
-	"github.com/unlock-music/cli/algo/common"
 	"strings"
+
+	"github.com/unlock-music/cli/algo/common"
 )
 
 type RawMeta interface {
@@ -10,6 +11,7 @@ type RawMeta interface {
 	GetFormat() string
 	GetAlbumImageURL() string
 }
+
 type RawMetaMusic struct {
 	Format        string          `json:"format"`
 	MusicID       int             `json:"musicId"`
@@ -30,11 +32,11 @@ type RawMetaMusic struct {
 func (m RawMetaMusic) GetAlbumImageURL() string {
 	return m.AlbumPic
 }
+
 func (m RawMetaMusic) GetArtists() (artists []string) {
 	for _, artist := range m.Artist {
 		for _, item := range artist {
-			name, ok := item.(string)
+			if name, ok := item.(string); ok {
-			if ok {
 				artists = append(artists, name)
 			}
 		}
@@ -49,6 +51,7 @@ func (m RawMetaMusic) GetTitle() string {
 func (m RawMetaMusic) GetAlbum() string {
 	return m.Album
 }
+
 func (m RawMetaMusic) GetFormat() string {
 	return m.Format
 }

algo/ncm/ncm.go

@@ -6,13 +6,14 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"errors"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
 	"github.com/unlock-music/cli/algo/common"
 	"github.com/unlock-music/cli/internal/logging"
 	"github.com/unlock-music/cli/internal/utils"
 	"go.uber.org/zap"
-	"io/ioutil"
-	"net/http"
-	"strings"
 )
 
 var (
@@ -65,6 +66,7 @@ func (d *Decoder) readKeyData() error {
 	if d.offsetKey == 0 || d.offsetKey+4 > d.fileLen {
 		return errors.New("invalid cover file offset")
 	}
+
 	bKeyLen := d.file[d.offsetKey : d.offsetKey+4]
 	iKeyLen := binary.LittleEndian.Uint32(bKeyLen)
 	d.offsetMeta = d.offsetKey + 4 + iKeyLen
@@ -82,9 +84,11 @@ func (d *Decoder) readMetaData() error {
 	if d.offsetMeta == 0 || d.offsetMeta+4 > d.fileLen {
 		return errors.New("invalid meta file offset")
 	}
+
 	bMetaLen := d.file[d.offsetMeta : d.offsetMeta+4]
 	iMetaLen := binary.LittleEndian.Uint32(bMetaLen)
 	d.offsetCover = d.offsetMeta + 4 + iMetaLen
+
 	if iMetaLen == 0 {
 		return errors.New("no any meta file found")
 	}
@@ -159,7 +163,9 @@ func (d *Decoder) readCoverData() error {
 	if iCoverLen == 0 {
 		return errors.New("no any cover file found")
 	}
+
 	d.cover = d.file[coverLenStart+4 : 4+coverLenStart+iCoverLen]
+
 	return nil
 }
 
@@ -167,6 +173,7 @@ func (d *Decoder) readAudioData() error {
 	if d.offsetAudio == 0 || d.offsetAudio > d.fileLen {
 		return errors.New("invalid audio offset")
 	}
+
 	audioRaw := d.file[d.offsetAudio:]
 	audioLen := len(audioRaw)
 	d.audio = make([]byte, audioLen)
@@ -186,6 +193,7 @@ func (d *Decoder) Decode() error {
 	if err == nil {
 		err = d.parseMeta()
 	}
+
 	if err != nil {
 		logging.Log().Warn("parse ncm meta file failed", zap.Error(err))
 	}
@@ -215,27 +223,32 @@ func (d Decoder) GetCoverImage() []byte {
 	if d.cover != nil {
 		return d.cover
 	}
+
 	{
 		imgURL := d.meta.GetAlbumImageURL()
 		if d.meta != nil && !strings.HasPrefix(imgURL, "http") {
 			return nil
 		}
+
 		resp, err := http.Get(imgURL)
 		if err != nil {
 			logging.Log().Warn("download image failed", zap.Error(err), zap.String("url", imgURL))
 			return nil
 		}
+
 		defer resp.Body.Close()
 		if resp.StatusCode != http.StatusOK {
 			logging.Log().Warn("download image failed", zap.String("http", resp.Status),
 				zap.String("url", imgURL))
 			return nil
 		}
+
 		data, err := ioutil.ReadAll(resp.Body)
 		if err != nil {
 			logging.Log().Warn("download image failed", zap.Error(err), zap.String("url", imgURL))
 			return nil
 		}
+
 		return data
 	}
 }

algo/qmc/cipher_map_test.go

@@ -22,6 +22,7 @@ func loadTestDataMapCipher(name string) ([]byte, []byte, []byte, error) {
 	}
 	return key, raw, target, nil
 }
+
 func Test_mapCipher_Decrypt(t *testing.T) {
 
 	tests := []struct {

algo/qmc/cipher_rc4.go

@@ -4,7 +4,7 @@ import (
 	"errors"
 )
 
-// A rc4Cipher is an instance of RC4 using a particular key.
+// rc4Cipher is an instance of RC4 using a particular key.
 type rc4Cipher struct {
 	box  []byte
 	key  []byte
@@ -87,6 +87,7 @@ func (c *rc4Cipher) Decrypt(src []byte, offset int) {
 			return
 		}
 	}
+
 	for toProcess > rc4SegmentSize {
 		c.encASegment(src[processed:processed+rc4SegmentSize], offset)
 		markProcess(rc4SegmentSize)
@@ -96,6 +97,7 @@ func (c *rc4Cipher) Decrypt(src []byte, offset int) {
 		c.encASegment(src[processed:], offset)
 	}
 }
+
 func (c *rc4Cipher) encFirstSegment(buf []byte, offset int) {
 	for i := 0; i < len(buf); i++ {
 		buf[i] ^= c.key[c.getSegmentSkip(offset+i)]
@@ -117,6 +119,7 @@ func (c *rc4Cipher) encASegment(buf []byte, offset int) {
 		}
 	}
 }
+
 func (c *rc4Cipher) getSegmentSkip(id int) int {
 	seed := int(c.key[id%c.n])
 	idx := int64(float64(c.hash) / float64((id+1)*seed) * 100.0)

algo/qmc/cipher_static.go

@@ -13,6 +13,7 @@ func (c *staticCipher) Decrypt(buf []byte, offset int) {
 		buf[i] ^= c.getMask(offset + i)
 	}
 }
+
 func (c *staticCipher) getMask(offset int) byte {
 	if offset > 0x7FFF {
 		offset %= 0x7FFF

algo/qmc/key_dec.go

@@ -16,17 +16,19 @@ func simpleMakeKey(salt byte, length int) []byte {
 	}
 	return keyBuf
 }
+
 func DecryptKey(rawKey []byte) ([]byte, error) {
 	rawKeyDec := make([]byte, base64.StdEncoding.DecodedLen(len(rawKey)))
 	n, err := base64.StdEncoding.Decode(rawKeyDec, rawKey)
 	if err != nil {
 		return nil, err
 	}
+
 	if n < 16 {
 		return nil, errors.New("key length is too short")
 	}
-	rawKeyDec = rawKeyDec[:n]
 
+	rawKeyDec = rawKeyDec[:n]
 	simpleKey := simpleMakeKey(106, 8)
 	teaKey := make([]byte, 16)
 	for i := 0; i < 8; i++ {
@@ -38,14 +40,17 @@ func DecryptKey(rawKey []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	return append(rawKeyDec[:8], rs...), nil
 }
+
 func decryptTencentTea(inBuf []byte, key []byte) ([]byte, error) {
 	const saltLen = 2
 	const zeroLen = 7
 	if len(inBuf)%8 != 0 {
 		return nil, errors.New("inBuf size not a multiple of the block size")
 	}
+
 	if len(inBuf) < 16 {
 		return nil, errors.New("inBuf size too small")
 	}
@@ -62,8 +67,8 @@ func decryptTencentTea(inBuf []byte, key []byte) ([]byte, error) {
 	if padLen+saltLen != 8 {
 		return nil, errors.New("invalid pad len")
 	}
-	out := make([]byte, outLen)
 
+	out := make([]byte, outLen)
 	ivPrev := make([]byte, 8)
 	ivCur := inBuf[:8]
 
@@ -80,6 +85,7 @@ func decryptTencentTea(inBuf []byte, key []byte) ([]byte, error) {
 		inBufPos += 8
 		destIdx = 0
 	}
+
 	for i := 1; i <= saltLen; {
 		if destIdx < 8 {
 			destIdx++
@@ -108,6 +114,7 @@ func decryptTencentTea(inBuf []byte, key []byte) ([]byte, error) {
 
 	return out, nil
 }
+
 func xor8Bytes(dst, a, b []byte) {
 	for i := 0; i < 8; i++ {
 		dst[i] = a[i] ^ b[i]

algo/qmc/key_dec_test.go

@@ -15,6 +15,7 @@ func TestSimpleMakeKey(t *testing.T) {
 		}
 	})
 }
+
 func loadDecryptKeyData(name string) ([]byte, []byte, error) {
 	keyRaw, err := os.ReadFile(fmt.Sprintf("./testdata/%s_key_raw.bin", name))
 	if err != nil {
@@ -26,6 +27,7 @@ func loadDecryptKeyData(name string) ([]byte, []byte, error) {
 	}
 	return keyRaw, keyDec, nil
 }
+
 func TestDecryptKey(t *testing.T) {
 	tests := []struct {
 		name     string
@@ -37,6 +39,7 @@ func TestDecryptKey(t *testing.T) {
 		{"mflac_rc4(256)", "mflac_rc4", false},
 		{"mgg_map(256)", "mgg_map", false},
 	}
+
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			raw, want, err := loadDecryptKeyData(tt.filename)

algo/qmc/qmc.go

@@ -100,10 +100,12 @@ func (d *Decoder) searchKey() error {
 	if err != nil {
 		return err
 	}
+
 	buf, err := io.ReadAll(io.LimitReader(d.r, 4))
 	if err != nil {
 		return err
 	}
+
 	if string(buf) == "QTag" {
 		if err := d.readRawMetaQTag(); err != nil {
 			return err
@@ -118,6 +120,7 @@ func (d *Decoder) searchKey() error {
 			return nil
 		}
 	}
+
 	return nil
 }
 
@@ -146,10 +149,12 @@ func (d *Decoder) readRawMetaQTag() error {
 	if _, err := d.r.Seek(-8, io.SeekEnd); err != nil {
 		return err
 	}
+
 	buf, err := io.ReadAll(io.LimitReader(d.r, 4))
 	if err != nil {
 		return err
 	}
+
 	rawMetaLen := int64(binary.BigEndian.Uint32(buf))
 
 	// read raw meta data
@@ -157,6 +162,7 @@ func (d *Decoder) readRawMetaQTag() error {
 	if err != nil {
 		return err
 	}
+
 	d.audioLen = int(audioLen)
 	rawMetaData, err := io.ReadAll(io.LimitReader(d.r, rawMetaLen))
 	if err != nil {
@@ -177,6 +183,7 @@ func (d *Decoder) readRawMetaQTag() error {
 	if err != nil {
 		return err
 	}
+
 	d.rawMetaExtra2, err = strconv.Atoi(items[2])
 	if err != nil {
 		return err

algo/qmc/qmc_test.go

@@ -24,8 +24,8 @@ func loadTestDataQmcDecoder(filename string) ([]byte, []byte, error) {
 		return nil, nil, err
 	}
 	return bytes.Join([][]byte{encBody, encSuffix}, nil), target, nil
-
 }
+
 func TestMflac0Decoder_Read(t *testing.T) {
 	tests := []struct {
 		name    string
@@ -60,7 +60,6 @@ func TestMflac0Decoder_Read(t *testing.T) {
 			}
 		})
 	}
-
 }
 
 func TestMflac0Decoder_Validate(t *testing.T) {

algo/tm/tm.go

@@ -3,6 +3,7 @@ package tm
 import (
 	"bytes"
 	"errors"
+
 	"github.com/unlock-music/cli/algo/common"
 )
 
@@ -75,5 +76,4 @@ func init() {
 	// QQ Music IOS Mp3
 	common.RegisterDecoder("tm0", false, common.NewRawDecoder)
 	common.RegisterDecoder("tm3", false, common.NewRawDecoder)
-
 }

algo/xm/xm.go

@@ -3,6 +3,7 @@ package xm
 import (
 	"bytes"
 	"errors"
+
 	"github.com/unlock-music/cli/algo/common"
 	"github.com/unlock-music/cli/internal/logging"
 	"go.uber.org/zap"
@@ -58,6 +59,7 @@ func (d *Decoder) Validate() error {
 	if lenData < 16 {
 		return ErrFileSize
 	}
+
 	if !bytes.Equal(magicHeader, d.file[:4]) ||
 		!bytes.Equal(magicHeader2, d.file[8:12]) {
 		return ErrMagicHeader
@@ -76,6 +78,7 @@ func (d *Decoder) Validate() error {
 	if d.headerLen+16 > uint32(lenData) {
 		return ErrFileSize
 	}
+
 	return nil
 }
 

cmd/um/main.go

@@ -9,17 +9,17 @@ import (
 	"sort"
 	"strings"
 
+	"github.com/unlock-music/cli/algo/common"
+	"github.com/unlock-music/cli/internal/logging"
 	"github.com/urfave/cli/v2"
 	"go.uber.org/zap"
 
-	"github.com/unlock-music/cli/algo/common"
 	_ "github.com/unlock-music/cli/algo/kgm"
 	_ "github.com/unlock-music/cli/algo/kwm"
 	_ "github.com/unlock-music/cli/algo/ncm"
 	_ "github.com/unlock-music/cli/algo/qmc"
 	_ "github.com/unlock-music/cli/algo/tm"
 	_ "github.com/unlock-music/cli/algo/xm"
-	"github.com/unlock-music/cli/internal/logging"
 )
 
 var AppVersion = "v0.0.6"
@@ -43,26 +43,30 @@ func main() {
 		HideHelpCommand: true,
 		UsageText:       "um [-o /path/to/output/dir] [--extra-flags] [-i] /path/to/input",
 	}
-	err := app.Run(os.Args)
+
-	if err != nil {
+	if err := app.Run(os.Args); err != nil {
 		logging.Log().Fatal("run app failed", zap.Error(err))
 	}
 }
+
 func printSupportedExtensions() {
 	exts := []string{}
 	for ext := range common.DecoderRegistry {
 		exts = append(exts, ext)
 	}
+
 	sort.Strings(exts)
 	for _, ext := range exts {
 		fmt.Printf("%s: %d\n", ext, len(common.DecoderRegistry[ext]))
 	}
 }
+
 func appMain(c *cli.Context) (err error) {
 	if c.Bool("supported-ext") {
 		printSupportedExtensions()
 		return nil
 	}
+
 	input := c.String("input")
 	if input == "" {
 		switch c.Args().Len() {
@@ -90,9 +94,6 @@ func appMain(c *cli.Context) (err error) {
 		}
 	}
 
-	skipNoop := c.Bool("skip-noop")
-	removeSource := c.Bool("remove-source")
-
 	inputStat, err := os.Stat(input)
 	if err != nil {
 		return err
@@ -110,26 +111,32 @@ func appMain(c *cli.Context) (err error) {
 		return errors.New("output should be a writable directory")
 	}
 
+	skipNoop := c.Bool("skip-noop")
+	removeSource := c.Bool("remove-source")
+
 	if inputStat.IsDir() {
 		return dealDirectory(input, output, skipNoop, removeSource)
-	} else {
-		allDec := common.GetDecoder(inputStat.Name(), skipNoop)
-		if len(allDec) == 0 {
-			logging.Log().Fatal("skipping while no suitable decoder")
-		}
-		return tryDecFile(input, output, allDec, removeSource)
 	}
 
+	allDec := common.GetDecoder(inputStat.Name(), skipNoop)
+	if len(allDec) == 0 {
+		logging.Log().Fatal("skipping while no suitable decoder")
+	}
+
+	return tryDecFile(input, output, allDec, removeSource)
 }
+
 func dealDirectory(inputDir string, outputDir string, skipNoop bool, removeSource bool) error {
 	items, err := os.ReadDir(inputDir)
 	if err != nil {
 		return err
 	}
+
 	for _, item := range items {
 		if item.IsDir() {
 			continue
 		}
+
 		allDec := common.GetDecoder(item.Name(), skipNoop)
 		if len(allDec) == 0 {
 			logging.Log().Info("skipping while no suitable decoder", zap.String("file", item.Name()))
@@ -141,6 +148,7 @@ func dealDirectory(inputDir string, outputDir string, skipNoop bool, removeSourc
 			logging.Log().Error("conversion failed", zap.String("source", item.Name()))
 		}
 	}
+
 	return nil
 }
 
@@ -159,9 +167,11 @@ func tryDecFile(inputFile string, outputDir string, allDec []common.NewDecoderFu
 		logging.Log().Warn("try decode failed", zap.Error(err))
 		dec = nil
 	}
+
 	if dec == nil {
 		return errors.New("no any decoder can resolve the file")
 	}
+
 	if err := dec.Decode(); err != nil {
 		return errors.New("failed while decoding: " + err.Error())
 	}
@@ -178,21 +188,20 @@ func tryDecFile(inputFile string, outputDir string, allDec []common.NewDecoderFu
 	filenameOnly := strings.TrimSuffix(filepath.Base(inputFile), filepath.Ext(inputFile))
 
 	outPath := filepath.Join(outputDir, filenameOnly+outExt)
-	err = os.WriteFile(outPath, outData, 0644)
+	if err = os.WriteFile(outPath, outData, 0644); err != nil {
-	if err != nil {
 		return err
 	}
 
 	// if source file need to be removed
-	if removeSource {
+	if !removeSource {
-		err := os.RemoveAll(inputFile)
-		if err != nil {
-			return err
-		}
-		logging.Log().Info("successfully converted, and source file is removed", zap.String("source", inputFile), zap.String("destination", outPath))
-	} else {
 		logging.Log().Info("successfully converted", zap.String("source", inputFile), zap.String("destination", outPath))
+		return nil
 	}
 
+	if err := os.RemoveAll(inputFile); err != nil {
+		return err
+	}
+	logging.Log().Info("successfully converted, and source file is removed", zap.String("source", inputFile), zap.String("destination", outPath))
+
 	return nil
 }

internal/logging/logging.go

@@ -4,9 +4,7 @@ import (
 	"os"
 	"sync"
 	"time"
-)
 
-import (
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )