forked from kilosonc/NCMconverter
/
ncm.go
217 lines (189 loc) · 4.53 KB
/
ncm.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
// Package ncm reads ncm file into memory, and cut it into different parts.
package ncm
import (
"io"
"log"
"os"
"strings"
"github.com/Arvintian/NCMconverter/path"
)
const (
// MagicHeader1 is used to check whether the file is ncm format file.
MagicHeader1 = 0x4e455443
MagicHeader2 = 0x4d414446
)
type Data struct {
Length uint64
Detail []byte
}
// NcmFile represents a ncm file on the computer
type NcmFile struct {
Path string
FileDir string
FileName string
fd *os.File
Ext string
valid bool
Key Data
Meta Data
Cover Data
Music Data
}
// NewNcmFile create a pointer to ncmfile
// ncmpath point out where the ncm file is.
func NewNcmFile(ncmpath string) (nf *NcmFile, err error) {
nf = new(NcmFile)
//if runtime.GOOS == "windows" {
// ncmpath = filepath.Clean(ncmpath)
// nf.FileName = filepath.Base(ncmpath)
// nf.FileDir = filepath.Dir(ncmpath)
// nf.Ext = filepath.Ext(ncmpath)
//} else if (runtime.GOOS) == "linux" {
// ncmpath = path.Clean(ncmpath)
// nf.FileName = path.Base(ncmpath)
// nf.FileDir = path.Dir(ncmpath)
// nf.Ext = path.Ext(ncmpath)
//}
ncmpath = path.Clean(ncmpath)
nf.FileName = path.Base(ncmpath)
nf.FileDir = path.Dir(ncmpath)
nf.Ext = path.Ext(ncmpath)
nf.Path = ncmpath
if nf.fd, err = os.Open(nf.Path); err != nil {
return nil, err
}
return
}
// Validate check the whether the file is ncm file
// by ext and header.
func (nf *NcmFile) Validate() error {
if !strings.EqualFold(nf.Ext, ".ncm") {
return ErrExtNcm
}
err := nf.CheckHeader()
if err != nil {
return err
}
nf.valid = true
return nil
}
// CheckHeader check whether file's first 4 bytes equal to MagicHeader1
// and the following 4 bytes equal to MagicHeader2.
func (nf *NcmFile) CheckHeader() error {
if _, err := nf.fd.Seek(0, io.SeekStart); err != nil {
return err
}
m1, err := readUint32(nf.fd)
m2, err := readUint32(nf.fd)
if err != nil {
return err
}
if m1 != MagicHeader1 && m2 != MagicHeader2 {
return ErrMagicHeader
}
return nil
}
// getData gets (a) uint32 format number as length,
// and the following (a) bytes data.
func (nf *NcmFile) getData(offset int64) ([]byte, uint32, error) {
if _, err := nf.fd.Seek(offset, io.SeekStart); err != nil {
return nil, 0, err
}
length, err := readUint32(nf.fd)
if err != nil {
return nil, 0, err
}
buf := make([]byte, length)
if _, err = nf.fd.Read(buf); err != nil {
return nil, 0, err
}
return buf, length, nil
}
// GetKey gets key used parse the music data.
func (nf *NcmFile) GetKey() (err error) {
tmp, length, err := nf.getData(4*2 + 2)
if err != nil {
return err
}
nf.Key.Length = uint64(length)
nf.Key.Detail = tmp
return nil
}
// GetMeta gets meta data describing the music.
func (nf *NcmFile) GetMeta() (err error) {
tmp, length, err := nf.getData(int64(4*2 + 2 + 4 + nf.Key.Length))
if err != nil {
return
}
nf.Meta.Detail = tmp
nf.Meta.Length = uint64(length)
return nil
}
// GetCover gets the cover of music.
func (nf *NcmFile) GetCover() (err error) {
tmp, length, err := nf.getData(int64(4*2 + 2 + 4 + nf.Key.Length + 4 + nf.Meta.Length + 5 + 4))
if err != nil {
return
}
nf.Cover.Detail = tmp
nf.Cover.Length = uint64(length)
return nil
}
// GetMusicData gets the decoded music data.
func (nf *NcmFile) GetMusicData() error {
nf.fd.Seek(int64(4*2+2+4+nf.Key.Length+4+nf.Meta.Length+9+4+nf.Cover.Length), io.SeekStart)
file := nf.fd
buf := make([]byte, 1024)
nf.Music.Detail = make([]byte, 0)
var (
length int
err error
)
for {
if length, err = file.Read(buf); err != nil && err != io.EOF {
return err
}
nf.Music.Detail = append(nf.Music.Detail, buf[:length]...)
nf.Music.Length += uint64(length)
if err == io.EOF {
return nil
}
}
}
// Close closes fd.
func (nf *NcmFile) Close() error {
return nf.fd.Close()
}
// Parse is a combination of Validate,GetKey,GetMeta,GetCover and GetMusicData
// cause these methods have to be called in order except Validata.
func (nf *NcmFile) Parse() error {
err := nf.Validate()
if err != nil {
log.Printf("Ncm magic header check failed: %v", err)
return err
}
err = nf.GetKey()
if err != nil {
log.Printf("Get Key Failed: %v", err)
return err
}
err = nf.GetMeta()
if err != nil {
log.Printf("Get Meta Failed: %v", err)
return err
}
err = nf.GetCover()
if err != nil {
log.Printf("Get Cover Failed: %v", err)
return err
}
err = nf.GetMusicData()
if err != nil {
log.Printf("Get Music Data Failed: %v", err)
return err
}
return nil
}
func (nf *NcmFile) GetFDStat() (os.FileInfo, error) {
return nf.fd.Stat()
}