Caleb Gardner
82 lines
1.4 KiB
Go
82 lines
1.4 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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master io.Reader
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cur io.Reader
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d decompress.Decompressor
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comRdr io.Reader
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}
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func NewReader(master io.Reader, d decompress.Decompressor) *Reader {
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return &Reader{
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master: master,
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d: d,
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}
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}
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func realSize(siz uint16) uint16 {
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return siz &^ 0x8000
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}
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func (r *Reader) advance() (err error) {
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if _, ok := r.d.(decompress.Resetable); !ok {
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if clr, ok := r.cur.(io.Closer); ok {
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clr.Close()
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}
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}
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var raw uint16
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err = binary.Read(r.master, binary.LittleEndian, &raw)
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if err != nil {
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return
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}
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size := realSize(raw)
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r.cur = io.LimitReader(r.master, int64(size))
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if size == raw {
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if rs, ok := r.d.(decompress.Resetable); ok {
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if r.comRdr == nil {
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r.cur, err = r.d.Reader(r.cur)
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if err != nil {
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return
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}
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} else {
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err = rs.Reset(r.comRdr, r.cur)
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r.cur = r.comRdr
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}
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} else {
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r.cur, err = r.d.Reader(r.cur)
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}
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}
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return
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}
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func (r *Reader) Read(p []byte) (n int, err error) {
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if r.cur == nil {
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err = r.advance()
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if err != nil {
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return
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}
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}
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n, err = r.cur.Read(p)
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if err == io.EOF {
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err = r.advance()
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if err != nil {
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return
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}
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var tmpN int
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tmp := make([]byte, len(p)-n)
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tmpN, err = r.Read(tmp)
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for i := 0; i < tmpN; i++ {
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p[n+i] = tmp[i]
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}
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n += tmpN
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}
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return
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}
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