lotus/fr32/readers.go
2020-05-29 01:33:00 +02:00

150 lines
2.9 KiB
Go

package fr32
import (
"io"
"math/bits"
"golang.org/x/xerrors"
"github.com/filecoin-project/specs-actors/actors/abi"
)
type padReader struct {
src io.Reader
left uint64
work []byte
}
func NewPadReader(src io.Reader, sz abi.UnpaddedPieceSize) (io.Reader, error) {
if err := sz.Validate(); err != nil {
return nil, xerrors.Errorf("bad piece size: %w", err)
}
buf := make([]byte, mtTresh*mtChunkCount(sz.Padded()))
return &padReader{
src: src,
left: uint64(sz.Padded()),
work: buf,
}, nil
}
func (r *padReader) Read(out []byte) (int, error) {
if r.left == 0 {
return 0, io.EOF
}
outTwoPow := 1 << (63 - bits.LeadingZeros64(uint64(len(out))))
if err := abi.PaddedPieceSize(outTwoPow).Validate(); err != nil {
return 0, xerrors.Errorf("output must be of valid padded piece size: %w", err)
}
todo := abi.PaddedPieceSize(outTwoPow).Unpadded()
if r.left < uint64(todo.Padded()) {
todo = abi.PaddedPieceSize(1 << (63 - bits.LeadingZeros64(r.left))).Unpadded()
}
r.left -= uint64(todo.Padded())
n, err := r.src.Read(r.work[:todo])
if err != nil && err != io.EOF {
return n, err
}
Pad(r.work[:todo], out[:todo.Padded()])
return int(todo.Padded()), err
}
func NewPadWriter(dst io.Writer, sz abi.UnpaddedPieceSize) (io.Writer, error) {
if err := sz.Validate(); err != nil {
return nil, xerrors.Errorf("bad piece size: %w", err)
}
buf := make([]byte, mtTresh*mtChunkCount(sz.Padded()))
// TODO: Real writer
r, w := io.Pipe()
pr, err := NewPadReader(r, sz)
if err != nil {
return nil, err
}
go func() {
for {
n, err := pr.Read(buf)
if err != nil && err != io.EOF {
r.CloseWithError(err)
return
}
if _, err := dst.Write(buf[:n]); err != nil {
r.CloseWithError(err)
return
}
}
}()
return w, err
}
type unpadReader struct {
src io.Reader
left uint64
work []byte
}
func NewUnpadReader(src io.Reader, sz abi.PaddedPieceSize) (io.Reader, error) {
if err := sz.Validate(); err != nil {
return nil, xerrors.Errorf("bad piece size: %w", err)
}
buf := make([]byte, mtTresh*mtChunkCount(sz))
return &unpadReader{
src: src,
left: uint64(sz),
work: buf,
}, nil
}
func (r *unpadReader) Read(out []byte) (int, error) {
if r.left == 0 {
return 0, io.EOF
}
chunks := len(out) / 127
outTwoPow := 1 << (63 - bits.LeadingZeros64(uint64(chunks*128)))
if err := abi.PaddedPieceSize(outTwoPow).Validate(); err != nil {
return 0, xerrors.Errorf("output must be of valid padded piece size: %w", err)
}
todo := abi.PaddedPieceSize(outTwoPow)
if r.left < uint64(todo) {
todo = abi.PaddedPieceSize(1 << (63 - bits.LeadingZeros64(r.left)))
}
r.left -= uint64(todo)
n, err := r.src.Read(r.work[:todo])
if err != nil && err != io.EOF {
return n, err
}
if n != int(todo) {
return 0, xerrors.Errorf("didn't read enough: %w", err)
}
Unpad(r.work[:todo], out[:todo.Unpadded()])
return int(todo.Unpadded()), err
}