Parse doubly linked sectors in order

fmp/fmp_debug.go

@@ -6,6 +6,19 @@ import (
 )
 
 func (f *FmpFile) ToDebugFile(fname string) {
+	f_sectors, err := os.Create(fname + ".sectors")
+	if err != nil {
+		panic(err)
+	}
+	defer func() {
+		if err := f_sectors.Close(); err != nil {
+			panic(err)
+		}
+	}()
+	for _, sect := range f.Sectors {
+		fmt.Fprintf(f_sectors, "%s\n", sect.String())
+	}
+
 	f_chunks, err := os.Create(fname + ".chunks")
 	if err != nil {
 		panic(err)
@@ -31,8 +44,12 @@ func (f *FmpFile) ToDebugFile(fname string) {
 	fmt.Fprint(f_dicts, f.Dictionary.String())
 }
 
+func (sect *FmpSector) String() string {
+	return fmt.Sprintf("<Sector id=%v del=%v, lev=%v, prevID=%v, nextID=%v>", sect.ID, sect.Deleted, sect.Level, sect.PrevID, sect.NextID)
+}
+
 func (c *FmpChunk) String() string {
-	return fmt.Sprintf("<%v(%v)>", c.Type, c.Length)
+	return fmt.Sprintf("<Chunk type=%v len=%v>", c.Type, c.Length)
 }
 
 func (dict *FmpDict) string(parentPath string) string {

fmp/fmp_file.go

@@ -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

fmp/fmp_test.go

@@ -10,8 +10,8 @@ func TestOpenFile(t *testing.T) {
 	if f.FileSize != 393216 {
 		t.Errorf("expected file size to be 393216, got %d", f.FileSize)
 	}
-	if f.numSectors != 96 {
-		t.Errorf("expected number of sectors to be 96, got %d", f.numSectors)
+	if f.numSectors != 95 {
+		t.Errorf("expected number of sectors to be 95, got %d", f.numSectors)
 	}
 	if f.CreatorName != "Pro 12.0" {
 		t.Errorf("expected application name to be 'Pro 12.0', got '%s'", f.CreatorName)

fmp/fmp_type.go

@@ -13,16 +13,21 @@ type FmpFile struct {
 	Chunks      []*FmpChunk
 	Dictionary  *FmpDict
 
-	numSectors uint
-	stream     io.ReadSeeker
+	numSectors      uint64 // Excludes the header sector
+	currentSectorID uint64
+
+	stream io.ReadSeeker
 }
 
 type FmpSector struct {
-	Deleted      bool
-	Level        uint8
-	PrevSectorID uint64
-	NextSectorID uint64
-	Chunks       []*FmpChunk
+	ID      uint64
+	Level   uint8
+	Deleted bool
+	PrevID  uint64
+	NextID  uint64
+	Prev    *FmpSector
+	Next    *FmpSector
+	Chunks  []*FmpChunk
 }
 
 type FmpChunk struct {