romein/go-fmp
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Code Issues Releases Activity

Parse doubly linked sectors in order

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This commit is contained in:
Romein van Buren
2025-06-13 12:09:39 +02:00
parent 6f3622be92
commit 7ff0cc8501
4 changed files with 64 additions and 28 deletions
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50
fmp/fmp_file.go
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@ -2,7 +2,6 @@ package fmp
import (
"bytes"
"encoding/hex"
"fmt"
"io"
"os"
@ -10,13 +9,16 @@ import (
)
const (
sectorSize = 4096
sectorHeaderSize = 20
sectorPayloadSize = sectorSize - sectorHeaderSize
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
sectorHeaderSize = 20
headerSize = sectorSize
magicSize = len(magicSequence)
hbamSize = len(hbamSequence)
)
func OpenFile(path string) (*FmpFile, error) {
@ -37,12 +39,11 @@ func OpenFile(path string) (*FmpFile, error) {
}
ctx.FileSize = uint(info.Size())
ctx.numSectors = ctx.FileSize / sectorSize
ctx.Sectors = make([]*FmpSector, ctx.numSectors)
ctx.numSectors = uint64((ctx.FileSize / sectorSize) - 1)
ctx.Sectors = make([]*FmpSector, 0)
currentPath := make([]uint64, 0)
for i := uint(0); i < ctx.numSectors; i++ {
for {
sector, err := ctx.readSector()
if err == io.EOF {
break
@ -50,7 +51,7 @@ func OpenFile(path string) (*FmpFile, error) {
if err != nil {
return nil, err
}
ctx.Sectors[i] = sector
ctx.Sectors = append(ctx.Sectors, sector)
ctx.Chunks = append(ctx.Chunks, sector.Chunks...)
for _, chunk := range sector.Chunks {
@ -89,13 +90,22 @@ func OpenFile(path string) (*FmpFile, error) {
// noop
}
}
ctx.currentSectorID = sector.NextID
if sector.NextID == 0 {
break
} else if sector.NextID > ctx.numSectors {
return nil, ErrBadHeader
} else {
ctx.stream.Seek(int64(sector.NextID*sectorSize), 0)
}
}
return ctx, nil
}
func (ctx *FmpFile) readHeader() error {
buf := make([]byte, sectorSize)
buf := make([]byte, headerSize)
_, err := ctx.stream.Read(buf)
if err != nil {
return err
@ -130,26 +140,30 @@ func (ctx *FmpFile) readSector() (*FmpSector, error) {
}
sector := &FmpSector{
Deleted: buf[0] != 0,
Level: uint8(buf[1]),
PrevSectorID: parseVarUint64(buf[2:6]),
NextSectorID: parseVarUint64(buf[6:10]),
ID: ctx.currentSectorID,
Deleted: buf[0] > 0,
Level: uint8(buf[1]),
PrevID: parseVarUint64(buf[4 : 4+4]),
NextID: parseVarUint64(buf[8 : 8+4]),
}
payload := make([]byte, sectorSize-sectorHeaderSize)
payload := make([]byte, sectorPayloadSize)
n, err = ctx.stream.Read(payload)
if n != sectorSize-sectorHeaderSize {
if n != sectorPayloadSize {
return nil, ErrRead
}
if err != nil {
return nil, ErrRead
}
sector.Chunks = make([]*FmpChunk, 0)
for {
chunk, err := ctx.readChunk(payload)
fmt.Printf("0x%02X", payload[0])
if chunk != nil {
fmt.Printf("%s - (type%v)\n", hex.EncodeToString([]byte{payload[0]}), int(chunk.Type))
fmt.Printf(" (type %v)\n", int(chunk.Type))
}
if err == io.EOF {
break