Caleb Gardner
6224c4be41
Further removed multiple pointer instances Re-use decompression readers (except zstd due to bugs)
66 lines
1.2 KiB
Go
66 lines
1.2 KiB
Go
package metadata
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"io"
|
|
|
|
"github.com/CalebQ42/squashfs/internal/decompress"
|
|
)
|
|
|
|
type Reader struct {
|
|
r io.Reader
|
|
d decompress.Decompressor
|
|
dat []byte
|
|
curOffset uint16
|
|
}
|
|
|
|
func NewReader(r io.Reader, d decompress.Decompressor) Reader {
|
|
return Reader{
|
|
r: r,
|
|
d: d,
|
|
}
|
|
}
|
|
|
|
func (r *Reader) advance() error {
|
|
r.curOffset = 0
|
|
dat := make([]byte, 2)
|
|
_, err := r.r.Read(dat)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
size := binary.LittleEndian.Uint16(dat)
|
|
realSize := size &^ 0x8000
|
|
r.dat = make([]byte, realSize)
|
|
_, err = r.r.Read(r.dat)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if size != realSize {
|
|
return nil
|
|
}
|
|
r.dat, err = r.d.Decompress(r.dat)
|
|
return err
|
|
}
|
|
|
|
func (r *Reader) Read(b []byte) (int, error) {
|
|
curRead := 0
|
|
var toRead int
|
|
for curRead < len(b) {
|
|
if r.curOffset >= uint16(len(r.dat)) {
|
|
if err := r.advance(); err != nil {
|
|
return curRead, err
|
|
}
|
|
}
|
|
toRead = min(len(b)-curRead, len(r.dat)-int(r.curOffset))
|
|
copy(b[curRead:], r.dat[r.curOffset:int(r.curOffset)+toRead])
|
|
r.curOffset += uint16(toRead)
|
|
curRead += toRead
|
|
}
|
|
return curRead, nil
|
|
}
|
|
|
|
func (r *Reader) Close() error {
|
|
r.dat = nil
|
|
return nil
|
|
}
|