Caleb Gardner
65 lines
1.2 KiB
Go
65 lines
1.2 KiB
Go
package metadata
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import (
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"encoding/binary"
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"io"
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"github.com/CalebQ42/squashfs/internal/decompress"
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)
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type Reader struct {
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r io.Reader
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d decompress.Decompressor
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dat []byte
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curOffset uint16
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}
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func NewReader(r io.Reader, d decompress.Decompressor) *Reader {
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return &Reader{
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r: r,
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d: d,
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}
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}
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func (r *Reader) advance() error {
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r.curOffset = 0
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var size uint16
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err := binary.Read(r.r, binary.LittleEndian, &size)
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if err != nil {
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return err
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}
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realSize := size &^ 0x8000
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r.dat = make([]byte, realSize)
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err = binary.Read(r.r, binary.LittleEndian, &r.dat)
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if err != nil {
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return err
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}
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if size != realSize {
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return nil
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}
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r.dat, err = r.d.Decompress(r.dat)
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return err
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}
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func (r *Reader) Read(b []byte) (int, error) {
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curRead := 0
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var toRead int
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for curRead < len(b) {
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if r.curOffset >= uint16(len(r.dat)) {
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if err := r.advance(); err != nil {
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return curRead, err
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}
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}
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toRead = min(len(b)-curRead, len(r.dat)-int(r.curOffset))
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copy(b[curRead:], r.dat[r.curOffset:int(r.curOffset)+toRead])
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r.curOffset += uint16(toRead)
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curRead += toRead
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}
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return curRead, nil
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}
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func (r *Reader) Close() error {
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r.dat = nil
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return nil
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}
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