Unbewohnte
/
id3ed
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Browse Source

⚫ Little progress towards writing support ⚫

main
Unbewohnte 3 years ago
parent
2a1b44de6c
commit
307feeb13f
3 changed files with 200 additions and 69 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 19
      util/bits.go
  2. 12
      util/bits_test.go
  3. 238
      v2/frame.go

19
util/bits.go
Unescape View File

@ -1,6 +1,19 @@
package util
// Tells if bit is set in given byte
func GetBit(n byte, bitN int) bool {
return n&byte(1<<bitN-1) != 0
// Tells if bit is set in given byte,
// if bitN <= 0 - always returns false
func GetBit(b byte, bitN int) bool {
if bitN == 0 {
return false
}
return b&byte(1<<bitN-1) != 0
}
// Sets bit to 1 in provided byte, if bitN <= 0
// returns original b without modifications
func SetBit(b byte, bitN int) byte {
if bitN == 0 {
return b
}
return b | byte(1<<byte(bitN)-1)
}

12
util/bits_test.go
Unescape View File

@ -12,3 +12,15 @@ func TestGetBit(t *testing.T) {
}
}
}
func TestSetBit(t *testing.T) {
var testByte byte = 0
if SetBit(testByte, 1) != 1 {
t.Errorf("SetBit failed: expected output %d; got %d", 1, SetBit(testByte, 1))
}
if SetBit(testByte, 8) != 255 {
t.Errorf("SetBit failed: expected output %d; got %d", 255, SetBit(testByte, 8))
}
}

238
v2/frame.go
Unescape View File

@ -14,12 +14,14 @@ var ErrInvalidFHeaderSize error = fmt.Errorf("frame header must be 6 or 10 bytes
var ErrInvalidID error = fmt.Errorf("invalid identifier")
type FrameFlags struct {
TagAlterPreservation bool
FileAlterPreservation bool
ReadOnly bool
Compressed bool
Encrypted bool
InGroup bool
TagAlterPreservation bool
FileAlterPreservation bool
ReadOnly bool
Compressed bool
Encrypted bool
InGroup bool
Unsyrchronised bool
HasDataLengthIndicator bool
}
type FrameHeader struct {
@ -47,83 +49,174 @@ func isValidFrameID(frameID []byte) bool {
return true
}
// Structuralises frame header from given bytes. For versions see: constants.
func getFrameHeader(fHeaderbytes []byte, version string) (FrameHeader, error) {
// validation check
if int(len(fHeaderbytes)) != int(10) && int(len(fHeaderbytes)) != int(6) {
return FrameHeader{}, ErrInvalidFHeaderSize
func getV22FrameHeader(fHeaderbytes []byte) (FrameHeader, error) {
var header FrameHeader
if !isValidFrameID(fHeaderbytes[0:3]) {
return FrameHeader{}, ErrInvalidID
}
header.ID = string(fHeaderbytes[0:3])
framesizeBytes := util.BytesToIntSynchsafe(fHeaderbytes[3:6])
header.Size = framesizeBytes
return header, nil
}
func getV23FrameHeader(fHeaderbytes []byte) (FrameHeader, error) {
var header FrameHeader
switch version {
case V2_2:
if !isValidFrameID(fHeaderbytes[0:3]) {
return FrameHeader{}, ErrInvalidID
}
header.ID = string(fHeaderbytes[0:3])
// ID
if !isValidFrameID(fHeaderbytes[0:4]) {
return FrameHeader{}, ErrInvalidID
}
header.ID = string(fHeaderbytes[0:4])
framesizeBytes := util.BytesToIntSynchsafe(fHeaderbytes[3:6])
header.Size = framesizeBytes
// Size
framesizeBytes := fHeaderbytes[4:8]
case V2_3:
fallthrough
framesize := util.BytesToIntSynchsafe(framesizeBytes)
case V2_4:
fallthrough
header.Size = framesize
default:
// ID
if !isValidFrameID(fHeaderbytes[0:4]) {
return FrameHeader{}, ErrInvalidID
}
header.ID = string(fHeaderbytes[0:4])
// Flags
frameFlags1 := fHeaderbytes[8]
frameFlags2 := fHeaderbytes[9]
// Size
framesizeBytes := fHeaderbytes[4:8]
var flags FrameFlags
framesize := util.BytesToIntSynchsafe(framesizeBytes)
if util.GetBit(frameFlags1, 1) {
flags.TagAlterPreservation = true
} else {
flags.TagAlterPreservation = false
}
if util.GetBit(frameFlags1, 2) {
flags.FileAlterPreservation = true
} else {
flags.FileAlterPreservation = false
}
if util.GetBit(frameFlags1, 3) {
flags.ReadOnly = true
} else {
flags.ReadOnly = false
}
if util.GetBit(frameFlags2, 1) {
flags.Compressed = true
} else {
flags.Compressed = false
}
if util.GetBit(frameFlags2, 1) {
flags.Encrypted = true
} else {
flags.Encrypted = false
}
if util.GetBit(frameFlags2, 1) {
flags.InGroup = true
} else {
flags.InGroup = false
}
header.Size = framesize
header.Flags = flags
// Flags
frameFlags1 := fHeaderbytes[8]
frameFlags2 := fHeaderbytes[9]
return header, nil
}
var flags FrameFlags
func getV24FrameHeader(fHeaderbytes []byte) (FrameHeader, error) {
var header FrameHeader
if util.GetBit(frameFlags1, 1) {
flags.TagAlterPreservation = true
} else {
flags.TagAlterPreservation = false
}
if util.GetBit(frameFlags1, 2) {
flags.FileAlterPreservation = true
} else {
flags.FileAlterPreservation = false
}
if util.GetBit(frameFlags1, 3) {
flags.ReadOnly = true
} else {
flags.ReadOnly = false
}
if util.GetBit(frameFlags2, 1) {
flags.Compressed = true
} else {
flags.Compressed = false
}
if util.GetBit(frameFlags2, 1) {
flags.Encrypted = true
} else {
flags.Encrypted = false
// ID
if !isValidFrameID(fHeaderbytes[0:4]) {
return FrameHeader{}, ErrInvalidID
}
header.ID = string(fHeaderbytes[0:4])
// Size
framesizeBytes := fHeaderbytes[4:8]
framesize := util.BytesToIntSynchsafe(framesizeBytes)
header.Size = framesize
// Flags
frameFlags1 := fHeaderbytes[8]
frameFlags2 := fHeaderbytes[9]
var flags FrameFlags
if util.GetBit(frameFlags1, 2) {
flags.TagAlterPreservation = true
} else {
flags.TagAlterPreservation = false
}
if util.GetBit(frameFlags1, 3) {
flags.FileAlterPreservation = true
} else {
flags.FileAlterPreservation = false
}
if util.GetBit(frameFlags1, 4) {
flags.ReadOnly = true
} else {
flags.ReadOnly = false
}
if util.GetBit(frameFlags2, 2) {
flags.InGroup = true
} else {
flags.InGroup = false
}
if util.GetBit(frameFlags2, 5) {
flags.Compressed = true
} else {
flags.Compressed = false
}
if util.GetBit(frameFlags2, 6) {
flags.Encrypted = true
} else {
flags.Encrypted = false
}
if util.GetBit(frameFlags2, 7) {
flags.Unsyrchronised = true
} else {
flags.Unsyrchronised = false
}
if util.GetBit(frameFlags2, 8) {
flags.HasDataLengthIndicator = true
} else {
flags.HasDataLengthIndicator = false
}
header.Flags = flags
return header, nil
}
// Structuralises frame header from given bytes. For versions see: constants.
func getFrameHeader(fHeaderbytes []byte, version string) (FrameHeader, error) {
// validation check
if int(len(fHeaderbytes)) != int(10) && int(len(fHeaderbytes)) != int(6) {
return FrameHeader{}, ErrInvalidFHeaderSize
}
var header FrameHeader
var err error
switch version {
case V2_2:
header, err = getV22FrameHeader(fHeaderbytes)
if err != nil {
return FrameHeader{}, err
}
if util.GetBit(frameFlags2, 1) {
flags.InGroup = true
} else {
flags.InGroup = false
case V2_3:
header, err = getV23FrameHeader(fHeaderbytes)
if err != nil {
return FrameHeader{}, err
}
header.Flags = flags
case V2_4:
header, err = getV24FrameHeader(fHeaderbytes)
if err != nil {
return FrameHeader{}, err
}
}
return header, nil
@ -174,6 +267,19 @@ func (f *Frame) Text() string {
return util.DecodeText(f.Contents)
}
// Converts frame to ready-to-write bytes
// func (f *Frame) ToBytes() []byte {
// buff := new(bytes.Buffer)
// // identifier
// buff.Write([]byte(f.Header.ID))
// // size
// buff.Write(util.IntToBytesSynchsafe(f.Header.Size))
// // flags
// return buff.Bytes()
// }
// Returns bytes of the frame that can be
// written into a file.
// func (f *Frame) Bytes() ([]byte, error) {

Write Preview
Loading…
Cancel
Save