Working on reading data.

Set up go modules
2020-11-20 03:59:38 -06:00
parent bc9adf8ade
commit fe0f4ef05f
7 changed files with 273 additions and 15 deletions
@@ -0,0 +1,141 @@
+package squashfs
+
+import (
+	"bytes"
+	"errors"
+	"io"
+)
+
+type DataReader struct {
+	r             *Reader
+	offset        int64 //offset relative to the beginning of the squash file
+	blocks        []DataBlock
+	curBlock      int //Which block in sizes is currently cached
+	curData       []byte
+	curReadOffset int //offset relative to the currently cached data
+	readOffset    int //offset relative to the beginning
+}
+
+type DataBlock struct {
+	begOffset        int64 //The offset relative to the beginning of the squash file. Makes it easier to seek to it.
+	size             uint32
+	compressed       bool
+	uncompressedSize uint32
+}
+
+func NewDataBlockSize(raw uint32) (dbs DataBlock) {
+	dbs.compressed = raw&1<<24 != 1<<24
+	dbs.size = raw &^ 1 << 24
+	if !dbs.compressed {
+		dbs.uncompressedSize = dbs.size
+	}
+	return
+}
+
+func (r *Reader) NewDataReader(offset int64, sizes []uint32) (*DataReader, error) {
+	var dr DataReader
+	dr.r = r
+	dr.offset = offset
+	for _, size := range sizes {
+		dr.blocks = append(dr.blocks, NewDataBlockSize(size))
+	}
+	err := dr.readCurBlock()
+	if err != nil {
+		return nil, err
+	}
+	return &dr, nil
+}
+
+func (d *DataReader) readNextBlock() error {
+	d.curBlock++
+	if d.curBlock >= len(d.blocks) {
+		d.curBlock--
+		return errors.New("Ran out of blocks")
+	}
+	err := d.readCurBlock()
+	if err != nil {
+		d.curBlock--
+		d.readCurBlock()
+		return err
+	}
+	return nil
+}
+
+func (d *DataReader) readCurBlock() error {
+	if d.blocks[d.curBlock].size == 0 {
+		d.curData = make([]byte, d.r.super.BlockSize)
+		d.blocks[d.curBlock].uncompressedSize = d.r.super.BlockSize
+		d.blocks[d.curBlock].begOffset = d.offset
+		return nil
+	}
+	sec := io.NewSectionReader(d.r.r, d.offset, int64(d.blocks[d.curBlock].size))
+	if d.blocks[d.curBlock].compressed {
+		btys, err := d.r.decompressor.Decompress(sec)
+		if err != nil {
+			return err
+		}
+		d.blocks[d.curBlock].uncompressedSize = uint32(len(btys))
+		d.curData = btys
+		d.blocks[d.curBlock].begOffset = d.offset
+		d.offset += int64(d.blocks[d.curBlock].size)
+		return nil
+	}
+	var buf bytes.Buffer
+	_, err := io.Copy(&buf, sec)
+	if err != nil {
+		return err
+	}
+	d.blocks[d.curBlock].begOffset = d.offset
+	d.offset += int64(d.blocks[d.curBlock].size)
+	return err
+}
+
+func (d *DataReader) Read(p []byte) (int, error) {
+	if d.curReadOffset+len(p) < len(d.curData) {
+		for i := 0; i < len(p); i++ {
+			p[i] = d.curData[d.curReadOffset+i]
+		}
+		d.readOffset += len(p)
+		d.curReadOffset += len(p)
+		return len(p), nil
+	}
+	read := 0
+	curRead := 0
+	for read < len(p) {
+		if d.curReadOffset == len(d.curData) {
+			err := d.readNextBlock()
+			if err != nil {
+				d.readOffset += read
+				return read, err
+			}
+			curRead = 0
+		}
+		for ; read < len(p); read++ {
+			curRead++
+			if d.curReadOffset+curRead < len(d.curData) {
+				p[read] = d.curData[d.readOffset+curRead]
+			} else {
+				break
+			}
+		}
+	}
+	d.readOffset += read
+	if read != len(p) {
+		return read, errors.New("Didn't read enough data")
+	}
+	return read, nil
+}
+
+func (d *DataReader) Seek(offset int64, whence int) (int, error) {
+	if whence == io.SeekStart {
+		d.readOffset = int(offset)
+		d.curReadOffset = int(offset)
+
+	}
+	switch whence {
+	case io.SeekCurrent:
+		d.readOffset += int(offset)
+		d.curReadOffset += int(offset)
+	case io.SeekStart:
+	}
+}
@@ -9,8 +9,9 @@ import (
 )

 type FragmentEntryRaw struct {
-	Start uint64
-	Size  uint32
+	Start   uint64
+	Size    uint32
+	_unused uint32
 }

 type FragmentEntry struct {
@@ -20,10 +21,10 @@ type FragmentEntry struct {
 }

 //NewFragmentEntry reads a fragment entry from the given io.Reader.
-func (r *Reader) NewFragmentEntry(rdr *io.Reader) (*FragmentEntry, error) {
+func (r *Reader) NewFragmentEntry(rdr io.Reader) (*FragmentEntry, error) {
 	var entry FragmentEntry
 	var raw FragmentEntryRaw
-	err := binary.Read(*rdr, binary.LittleEndian, &raw)
+	err := binary.Read(rdr, binary.LittleEndian, &raw)
 	if err != nil {
 		return nil, err
 	}
@@ -33,16 +34,52 @@ func (r *Reader) NewFragmentEntry(rdr *io.Reader) (*FragmentEntry, error) {
 	return &entry, nil
 }

-//GetFragmentFromInode returns the fragment data for a given inode
-func (r *Reader) GetFragmentFromInode(in *inode.Inode) ([]byte, error) {
-	if in.Type != inode.BasicFileType {
-		return nil, errors.New("Only basic file is supported right now")
-	}
-	bf := in.Info.(inode.BasicFile)
+//GetFragmentDataFromInode returns the fragment data for a given inode.
+//If the inode does not have a fragment, harmlessly returns an empty slice without an error.
+func (r *Reader) GetFragmentDataFromInode(in *inode.Inode) ([]byte, error) {
 	var size uint32
-	if bf.Init.BlockStart == 0 {
-		size = bf.Init.Size
+	var fragIndex uint32
+	var fragOffset uint32
+	if in.Type == inode.BasicFileType {
+		bf := in.Info.(inode.BasicFile)
+		if !bf.Fragmented {
+			return make([]byte, 0), nil
+		}
+		if bf.Init.BlockStart == 0 {
+			size = bf.Init.Size
+		} else {
+			size = bf.BlockSizes[len(bf.BlockSizes)-1]
+		}
+		fragIndex = bf.Init.FragmentIndex
+		fragOffset = bf.Init.FragmentOffset
+	} else if in.Type == inode.ExtFileType {
+		bf := in.Info.(inode.ExtendedFile)
+		if !bf.Fragmented {
+			return make([]byte, 0), nil
+		}
+		if bf.Init.BlockStart == 0 {
+			size = bf.Init.Size
+		} else {
+			size = bf.BlockSizes[len(bf.BlockSizes)-1]
+		}
+		fragIndex = bf.Init.FragmentIndex
+		fragOffset = bf.Init.FragmentOffset
 	} else {
-		size = bf.BlockSizes
+		return nil, errors.New("Inode type not supported")
 	}
+	frag := r.fragEntries[fragIndex]
+	datRdr, err := r.NewDataReader(int64(frag.start), []uint32{frag.size})
+	if err != nil {
+		return nil, err
+	}
+	_, err = datRdr.Seek(int64(fragOffset), io.SeekStart)
+	if err != nil {
+		return nil, err
+	}
+	tmp := make([]byte, size)
+	_, err = datRdr.Read(tmp)
+	if err != nil {
+		return nil, err
+	}
+	return tmp, nil
 }
@@ -0,0 +1,5 @@
+module github.com/CalebQ42/GoSquashfs
+
+go 1.15
+
+require github.com/CalebQ42/GoAppImage v0.4.0
@@ -0,0 +1,43 @@
+github.com/CalebQ42/GoAppImage v0.4.0 h1:aF+Y/vyo/RGhoyZEW1CMY6WyRWrZZO4ydsRFAtIGnaY=
+github.com/CalebQ42/GoAppImage v0.4.0/go.mod h1:qHudJKAn/dlkNWNnH4h1YKXp29EZ7Bppsn7sNP2HuvU=
+github.com/adrg/xdg v0.2.2 h1:A7ZHKRz5KGOLJX/bg7IPzStryhvCzAE1wX+KWawPiAo=
+github.com/adrg/xdg v0.2.2/go.mod h1:7I2hH/IT30IsupOpKZ5ue7/qNi3CoKzD6tL3HwpaRMQ=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.4.0 h1:xsAVV57WRhGj6kEIi8ReJzQlHHqcBYCElAvkovg3B/4=
+github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8=
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
+github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
+github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
+github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=
+github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+go.lsp.dev/uri v0.3.0 h1:KcZJmh6nFIBeJzTugn5JTU6OOyG0lDOo3R9KwTxTYbo=
+go.lsp.dev/uri v0.3.0/go.mod h1:P5sbO1IQR+qySTWOCnhnK7phBx+W3zbLqSMDJNTw88I=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b h1:QRR6H1YWRnHb4Y/HeNFCTJLFVxaq6wH4YuVdsUOr75U=
+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/ini.v1 v1.62.0 h1:duBzk771uxoUuOlyRLkHsygud9+5lrlGjdFBb4mSKDU=
+gopkg.in/ini.v1 v1.62.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
@@ -151,6 +151,7 @@ type ExtendedFileInit struct {
 type ExtendedFile struct {
 	Init       ExtendedFileInit
 	BlockSizes []uint32
+	Fragmented bool
 }

 //NewExtendedFile creates a new ExtendedFile
@@ -160,6 +161,7 @@ func NewExtendedFile(rdr io.Reader, blockSize uint32) (ExtendedFile, error) {
 	if err != nil {
 		return inode, err
 	}
+	inode.Fragmented = inode.Init.FragmentIndex != 0xFFFFFFFF
 	blocks := inode.Init.Size / blockSize
 	if inode.Init.Size%blockSize > 0 {
 		blocks++
@@ -7,7 +7,6 @@ import (
 	"io"
 	"strings"

-	"github.com/CalebQ42/GoSquashfs/internal/directory"
 	"github.com/CalebQ42/GoSquashfs/internal/inode"
 )

@@ -22,6 +21,9 @@ var (
 	ErrIncompatibleCompression = errors.New("Compression type unsupported")
 	//ErrCompressorOptions is returned if compressor options is present. It's not currently supported.
 	ErrCompressorOptions = errors.New("Compressor options is not currently supported")
+	//ErrFragmentTableIssues is returned if there's trouble reading the fragment table when creating a reader.
+	//When this is returned, the reader is still returned.
+	ErrFragmentTableIssues = errors.New("Trouble while reading the fragment table")
 )

 //Reader processes and reads a squashfs archive.
@@ -31,7 +33,7 @@ type Reader struct {
 	super        Superblock
 	flags        SuperblockFlags
 	decompressor Decompressor
-	dirs         []*directory.Directory
+	fragEntries  []*FragmentEntry
 }

 //NewSquashfsReader returns a new squashfs.Reader from an io.ReaderAt
@@ -56,6 +58,17 @@ func NewSquashfsReader(r io.ReaderAt) (*Reader, error) {
 		//TODO: parse compressor options
 		return nil, ErrCompressorOptions
 	}
+	br, err := rdr.NewBlockReader(int64(rdr.super.FragTableStart))
+	if err != nil {
+		return &rdr, err
+	}
+	for i := 0; i < int(rdr.super.FragCount); i++ {
+		entry, err := rdr.NewFragmentEntry(br)
+		if err != nil {
+			return &rdr, err
+		}
+		rdr.fragEntries = append(rdr.fragEntries, entry)
+	}
 	return &rdr, nil
 }

@@ -39,6 +39,23 @@ func TestMain(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	i, err := rdr.GetInodeFromPath("code-oss.desktop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	os.Remove(wd + "/testing/code-oss.desktop")
+	desk, err := os.Create(wd + "/testing/code-oss.desktop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	btys, err := rdr.GetFragmentDataFromInode(i)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = desk.Write(btys)
+	if err != nil {
+		t.Fatal(err)
+	}
 	t.Fatal("No problems here!")
 }