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reader.go
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reader.go
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package data
import (
"bytes"
"io"
"github.com/sylabs/squashfs/internal/decompress"
)
type Reader struct {
master io.Reader
cur io.Reader
fragRdr io.Reader
d decompress.Decompressor
comRdr io.Reader
blockSizes []uint32
blockSize uint32
resetable bool
}
func NewReader(r io.Reader, d decompress.Decompressor, blockSizes []uint32, blockSize uint32) *Reader {
return &Reader{
d: d,
master: r,
blockSizes: blockSizes,
blockSize: blockSize,
resetable: true,
}
}
func (r *Reader) AddFragment(rdr io.Reader) {
r.fragRdr = rdr
r.blockSizes = append(r.blockSizes, 0)
}
func realSize(siz uint32) uint32 {
return siz &^ (1 << 24)
}
func (r *Reader) advance() (err error) {
if clr, ok := r.cur.(io.Closer); ok {
clr.Close()
}
if len(r.blockSizes) == 0 {
return io.EOF
}
if len(r.blockSizes) == 1 && r.fragRdr != nil {
r.cur = r.fragRdr
} else {
size := realSize(r.blockSizes[0])
if size == 0 {
r.cur = bytes.NewReader(make([]byte, r.blockSize))
} else {
r.cur = io.LimitReader(r.master, int64(size))
if size == r.blockSizes[0] {
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)
}
}
}
}
r.blockSizes = r.blockSizes[1:]
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 := range tmp {
p[n+i] = tmp[i]
}
n += tmpN
}
return
}