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reader.go
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/
reader.go
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package metadata
import (
"encoding/binary"
"io"
"github.com/sylabs/squashfs/internal/decompress"
)
type Reader struct {
master io.Reader
cur io.Reader
d decompress.Decompressor
comRdr io.Reader
}
func NewReader(master io.Reader, d decompress.Decompressor) *Reader {
return &Reader{
master: master,
d: d,
}
}
func realSize(siz uint16) uint16 {
return siz &^ 0x8000
}
func (r *Reader) advance() (err error) {
if !r.d.Resetable() {
if clr, ok := r.cur.(io.Closer); ok {
clr.Close()
}
}
var raw uint16
err = binary.Read(r.master, binary.LittleEndian, &raw)
if err != nil {
return
}
size := realSize(raw)
r.cur = io.LimitReader(r.master, int64(size))
if size == raw {
if r.d.Resetable() {
if r.comRdr == nil {
r.cur, err = r.d.Reader(r.cur)
if err != nil {
return
}
} else {
err = r.d.Reset(r.comRdr, r.cur)
r.cur = r.comRdr
}
} else {
r.cur, err = r.d.Reader(r.cur)
}
}
return
}
func (r *Reader) Read(p []byte) (n int, err error) {
if r.cur == nil {
err = r.advance()
if err != nil {
return
}
}
n, err = r.cur.Read(p)
if err == io.EOF {
err = r.advance()
if err != nil {
return
}
var tmpN int
tmp := make([]byte, len(p)-n)
tmpN, err = r.Read(tmp)
for i := 0; i < tmpN; i++ {
p[n+i] = tmp[i]
}
n += tmpN
}
return
}