Caleb Gardner
82 lines
1.8 KiB
Go
82 lines
1.8 KiB
Go
package data
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import (
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"errors"
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"io"
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"github.com/CalebQ42/squashfs/internal/decompress"
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)
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type FullReader struct {
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fileSize uint64
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blockSize uint32
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rdr io.ReaderAt
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decomp decompress.Decompressor
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sizes []uint32
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blockOffsets []uint64
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fragDat []byte
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}
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func NewFullReader(rdr io.ReaderAt, decomp decompress.Decompressor, size uint64, start uint64, blockSizes []uint32) FullReader {
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out := FullReader{
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fileSize: size,
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rdr: rdr,
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decomp: decomp,
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sizes: blockSizes,
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}
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out.blockOffsets = make([]uint64, len(blockSizes))
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curOffset := start
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for i := range blockSizes {
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out.blockOffsets[i] = curOffset
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curOffset += uint64(blockSizes[i]) &^ (1 << 24)
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}
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return out
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}
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func (f *FullReader) AddFragData(blockStart uint64, offset uint32, blockSize uint32) error {
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realSize := blockSize &^ (1 << 24)
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dat := make([]byte, realSize)
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_, err := f.rdr.ReadAt(dat, int64(blockStart))
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if err != nil {
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return err
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}
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if blockSize == realSize {
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dat, err = f.decomp.Decompress(dat)
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if err != nil {
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return err
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}
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}
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f.fragDat = dat[offset : offset+uint32(f.fileSize%uint64(f.blockSize))]
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return nil
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}
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// Returns the data block at the given index
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func (f FullReader) Block(i int) ([]byte, error) {
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if i == len(f.sizes) && f.fragDat != nil {
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return f.fragDat, nil
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}
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if i >= len(f.sizes) {
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return nil, errors.New("invalid block index")
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}
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realSize := f.sizes[i] &^ (1 << 24)
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if realSize == 0 {
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if i == len(f.sizes)-1 && f.fragDat == nil {
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return make([]byte, f.fileSize%uint64(f.blockSize)), nil
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}
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return make([]byte, f.blockSize), nil
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}
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dat := make([]byte, realSize)
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_, err := f.rdr.ReadAt(dat, int64(f.blockOffsets[i]))
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if err != nil {
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return nil, err
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}
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if realSize == f.sizes[i] {
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return f.decomp.Decompress(dat)
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}
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return dat, nil
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}
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func (f FullReader) WriteTo(w io.Writer) (int64, error) {
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}
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