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Chunk parsing (WIP)

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Romein van Buren
2025-06-11 21:52:52 +02:00
parent d8f75521b2
commit ed56c54e68
5 changed files with 335 additions and 40 deletions
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245
fmp/fmp_chunk.go Normal file
View File

@ -0,0 +1,245 @@
package fmp
import (
"encoding/binary"
"fmt"
)
type FmpChunk struct {
Type FmpChunkType
Length uint32
Key uint32 // If Type == FMP_CHUNK_SHORT_KEY_VALUE or FMP_CHUNK_LONG_KEY_VALUE
Index uint32 // Segment index, if Type == FMP_CHUNK_SEGMENTED_DATA
Value []byte
}
func (c *FmpChunk) String() string {
return fmt.Sprintf("<%v(%v)>", c.Type, c.Length)
}
func (ctx *FmpFile) readChunk(payload []byte) (*FmpChunk, error) {
// Simple data
if payload[0] == 0x00 || payload[0] == 0x19 || payload[0] == 0x23 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+1],
Length: 2,
}, nil
}
if payload[0] == 0x08 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+2],
Length: 3,
}, nil
}
if payload[0] == 0x0E && payload[1] == 0xFF {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[2 : 2+5],
Length: 7,
}, nil
}
if 0x10 <= payload[0] && payload[0] <= 0x11 {
length := 3 + (payload[0] - 0x10)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+length],
Length: 1 + uint32(length),
}, nil
}
if 0x12 <= payload[0] && payload[0] <= 0x15 {
length := 1 + 2*(payload[0]-0x10)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+length],
Length: 1 + uint32(length),
}, nil
}
if 0x1A <= payload[0] && payload[0] <= 0x1D {
length := 2 * (payload[0] - 0x19)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_DATA,
Value: payload[1 : 1+length],
Length: 1 + uint32(length),
}, nil
}
// Simple key-value
if payload[0] == 0x01 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint32(payload[1]),
Value: payload[2 : 2+1],
Length: 3,
}, nil
}
if 0x02 <= payload[0] && payload[0] <= 0x05 {
length := 2 * (payload[0] - 1)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint32(payload[1]),
Value: payload[2 : 2+length],
Length: 2 + uint32(length),
}, nil
}
if payload[0] == 0x06 {
length := payload[2]
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: uint32(payload[1]),
Value: payload[3 : 3+length], // docs say offset 2?
Length: 3 + uint32(length),
}, nil
}
if payload[0] == 0x09 {
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[1:3]),
Value: payload[3 : 3+1], // docs say offset 2?
Length: 4,
}, nil
}
if 0x0A <= payload[0] && payload[0] <= 0x0D {
length := 2 * (payload[0] - 9)
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[1:3]),
Value: payload[3 : 3+length], // docs say offset 2?
Length: 2 + uint32(length),
}, nil
}
if payload[0] == 0x0E {
length := payload[2]
return &FmpChunk{
Type: FMP_CHUNK_SIMPLE_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[1:3]),
Value: payload[4 : 4+length], // docs say offset 2?
Length: 4 + uint32(length),
}, nil
}
// Long key-value
if payload[0] == 0x16 {
length := payload[4]
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[1 : 1+3]),
Value: payload[5 : 5+length],
Length: 5 + uint32(length),
}, nil
}
if payload[0] == 0x17 {
length := binary.BigEndian.Uint32(payload[1 : 1+3])
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[4 : 4+2]),
Value: payload[6 : 6+length],
Length: 6 + uint32(length),
}, nil
}
if payload[0] == 0x1E {
keyLength := payload[1]
valueLength := payload[2+keyLength]
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[2 : 2+keyLength]),
Value: payload[2+keyLength+1 : 2+keyLength+1+valueLength],
Length: 3 + uint32(keyLength) + uint32(valueLength),
}, nil
}
if payload[0] == 0x1F {
keyLength := uint32(payload[1])
valueLength := binary.BigEndian.Uint32(payload[2+keyLength : 2+keyLength+2+1])
return &FmpChunk{
Type: FMP_CHUNK_LONG_KEY_VALUE,
Key: binary.BigEndian.Uint32(payload[2 : 2+keyLength]),
Value: payload[2+keyLength+2 : 2+keyLength+2+valueLength],
Length: 4 + uint32(keyLength) + uint32(valueLength),
}, nil
}
// Segmented data
if payload[0] == 0x07 {
length := binary.BigEndian.Uint32(payload[2 : 2+2])
return &FmpChunk{
Type: FMP_CHUNK_SEGMENTED_DATA,
Index: uint32(payload[1]),
Value: payload[4 : 4+length],
Length: 4 + uint32(length),
}, nil
}
if payload[0] == 0x0F {
length := binary.BigEndian.Uint32(payload[3 : 3+2])
return &FmpChunk{
Type: FMP_CHUNK_SEGMENTED_DATA,
Index: binary.BigEndian.Uint32(payload[1 : 1+2]),
Value: payload[5 : 5+length],
Length: 5 + uint32(length),
}, nil
}
// Path push
if payload[0] == 0x20 || payload[0] == 0x0E {
if payload[1] == 0xFE {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+8],
Length: 10,
}, nil
}
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+1],
Length: 2,
}, nil
}
if payload[0] == 0x28 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+2],
Length: 3,
}, nil
}
if payload[0] == 0x30 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[1 : 1+3],
Length: 4,
}, nil
}
if payload[0] == 0x38 {
length := payload[1]
return &FmpChunk{
Type: FMP_CHUNK_PATH_PUSH,
Value: payload[2 : 2+length],
Length: 2 + uint32(length),
}, nil
}
// Path pop
if payload[0] == 0x3D && payload[1] == 0x40 {
return &FmpChunk{
Type: FMP_CHUNK_PATH_POP,
Length: 1,
}, nil
}
// No-op
if payload[0] == 0x80 {
return &FmpChunk{
Type: FMP_CHUNK_NOOP,
Length: 1,
}, nil
}
return nil, nil
}

23
fmp/fmp_const.go
View File

@ -1,5 +1,28 @@
package fmp
type FmpError string
type FmpChunkType uint8
func (e FmpError) Error() string { return string(e) }
var (
ErrRead = FmpError("read error")
ErrBadMagic = FmpError("bad magic number")
ErrBadHeader = FmpError("bad header")
ErrUnsupportedCharset = FmpError("unsupported character set")
ErrBadSectorCount = FmpError("bad sector count")
)
const (
FMP_CHUNK_SIMPLE_DATA FmpChunkType = iota
FMP_CHUNK_SEGMENTED_DATA
FMP_CHUNK_SIMPLE_KEY_VALUE
FMP_CHUNK_LONG_KEY_VALUE
FMP_CHUNK_PATH_PUSH
FMP_CHUNK_PATH_POP
FMP_CHUNK_NOOP
)
const (
FMP_COLLATION_ENGLISH = 0x00
FMP_COLLATION_FRENCH = 0x01

18
fmp/fmp_error.go
View File

@ -1,18 +0,0 @@
package fmp
type FmpError string
func (e FmpError) Error() string { return string(e) }
var (
ErrRead = FmpError("read error")
ErrBadMagic = FmpError("bad magic number")
ErrBadHeader = FmpError("bad header")
ErrUnsupportedCharset = FmpError("unsupported character set")
ErrBadSectorCount = FmpError("bad sector count")
ErrNoFmemopen = FmpError("no fmemopen")
ErrOpen = FmpError("could not open file")
ErrSeek = FmpError("seek failed")
ErrMalloc = FmpError("malloc failed")
ErrUserAborted = FmpError("user aborted")
)

84
fmp/fmp.go → fmp/fmp_file.go
View File

@ -12,19 +12,19 @@ const (
magicSequence = "\x00\x01\x00\x00\x00\x02\x00\x01\x00\x05\x00\x02\x00\x02\xC0"
hbamSequence = "HBAM7"
magicSize = len(magicSequence)
hbamSize = len(hbamSequence)
sectorSize = 4096
magicSize = len(magicSequence)
hbamSize = len(hbamSequence)
sectorSize = 4096
sectorHeaderSize = 20
)
type FmpFile struct {
Stream io.ReadSeeker
FileSize uint
NumSectors uint
VersionDate time.Time
ApplicationName string
VersionDate time.Time
CreatorName string
FileSize uint
NumSectors uint
Stream io.ReadSeeker
Sectors []*FmpSector
}
type FmpSector struct {
@ -32,7 +32,7 @@ type FmpSector struct {
Level uint8
PrevSectorID uint32
NextSectorID uint32
Payload []byte
Chunks []*FmpChunk
}
func OpenFile(path string) (*FmpFile, error) {
@ -40,20 +40,30 @@ func OpenFile(path string) (*FmpFile, error) {
if err != nil {
return nil, err
}
stream, err := os.Open(path)
if err != nil {
if stream != nil {
stream.Close()
}
return nil, err
}
defer stream.Close()
ctx := &FmpFile{Stream: stream}
if err := ctx.readHeader(); err != nil {
stream.Close()
return nil, err
}
ctx.FileSize = uint(info.Size())
ctx.NumSectors = ctx.FileSize / sectorSize
ctx.Sectors = make([]*FmpSector, ctx.NumSectors)
for i := uint(0); i < ctx.NumSectors; i++ {
sector, err := ctx.readSector()
if err != nil {
return nil, err
}
ctx.Sectors[i] = sector
}
return ctx, nil
}
@ -61,7 +71,7 @@ func (ctx *FmpFile) readHeader() error {
buf := make([]byte, sectorSize)
_, err := ctx.Stream.Read(buf)
if err != nil {
return ErrRead
return err
}
if !bytes.Equal(buf[:magicSize], []byte(magicSequence)) {
return ErrBadMagic
@ -76,23 +86,57 @@ func (ctx *FmpFile) readHeader() error {
}
appNameLength := int(buf[541])
ctx.ApplicationName = string(buf[542 : 542+appNameLength])
ctx.CreatorName = string(buf[542 : 542+appNameLength])
return nil
}
func (ctx *FmpFile) readSector() (*FmpSector, error) {
buf := make([]byte, sectorSize)
_, err := ctx.Stream.Read(buf)
buf := make([]byte, sectorHeaderSize)
n, err := ctx.Stream.Read(buf)
if n == 0 {
return nil, io.EOF
}
if err != nil {
return nil, ErrRead
}
sector := &FmpSector{
Deleted: buf[0] != 0,
Level: uint8(buf[1]),
PrevSectorID: binary.BigEndian.Uint32(buf[2:6]),
NextSectorID: binary.BigEndian.Uint32(buf[6:10]),
Payload: buf[6:4076],
}
payload := make([]byte, sectorSize-sectorHeaderSize)
n, err = ctx.Stream.Read(payload)
if n != sectorSize-sectorHeaderSize {
return nil, ErrRead
}
if err != nil {
return nil, ErrRead
}
sector.Chunks = make([]*FmpChunk, 0)
for {
chunk, err := ctx.readChunk(payload)
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
sector.Chunks = append(sector.Chunks, chunk)
if chunk == nil {
break
}
if chunk.Length == 0 {
panic("chunk length not set")
}
print(chunk.String() + "\n")
payload = payload[chunk.Length:]
}
return sector, nil
}

5
fmp/fmp_test.go
View File

@ -13,10 +13,11 @@ func TestOpenFile(t *testing.T) {
if f.NumSectors != 96 {
t.Errorf("expected number of sectors to be 96, got %d", f.NumSectors)
}
if f.ApplicationName != "Pro 12.0" {
t.Errorf("expected application name to be 'Pro 12.0', got '%s'", f.ApplicationName)
if f.CreatorName != "Pro 12.0" {
t.Errorf("expected application name to be 'Pro 12.0', got '%s'", f.CreatorName)
}
if f.VersionDate.Format("2006-01-02") != "2025-01-11" {
t.Errorf("expected version date to be '2025-01-11', got '%s'", f.VersionDate.Format("2006-01-02"))
}
print(f.Sectors[0])
}