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