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116 lines
3.7 KiB
116 lines
3.7 KiB
/*
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* Minio Cloud Storage, (C) 2017 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package cmd
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import (
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"crypto/subtle"
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"hash"
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"github.com/klauspost/reedsolomon"
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"github.com/minio/minio/pkg/errors"
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)
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// OfflineDisk represents an unavailable disk.
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var OfflineDisk StorageAPI // zero value is nil
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// ErasureFileInfo contains information about an erasure file operation (create, read, heal).
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type ErasureFileInfo struct {
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Size int64
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Algorithm BitrotAlgorithm
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Checksums [][]byte
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}
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// ErasureStorage represents an array of disks.
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// The disks contain erasure coded and bitrot-protected data.
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type ErasureStorage struct {
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disks []StorageAPI
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erasure reedsolomon.Encoder
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dataBlocks, parityBlocks int
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}
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// NewErasureStorage creates a new ErasureStorage. The storage erasure codes and protects all data written to
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// the disks.
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func NewErasureStorage(disks []StorageAPI, dataBlocks, parityBlocks int) (s ErasureStorage, err error) {
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erasure, err := reedsolomon.New(dataBlocks, parityBlocks)
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if err != nil {
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return s, errors.Tracef("failed to create erasure coding: %v", err)
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}
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s = ErasureStorage{
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disks: make([]StorageAPI, len(disks)),
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erasure: erasure,
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dataBlocks: dataBlocks,
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parityBlocks: parityBlocks,
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}
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copy(s.disks, disks)
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return
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}
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// ErasureEncode encodes the given data and returns the erasure-coded data.
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// It returns an error if the erasure coding failed.
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func (s *ErasureStorage) ErasureEncode(data []byte) ([][]byte, error) {
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encoded, err := s.erasure.Split(data)
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if err != nil {
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return nil, errors.Tracef("failed to split data: %v", err)
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}
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if err = s.erasure.Encode(encoded); err != nil {
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return nil, errors.Tracef("failed to encode data: %v", err)
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}
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return encoded, nil
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}
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// ErasureDecodeDataBlocks decodes the given erasure-coded data.
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// It only decodes the data blocks but does not verify them.
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// It returns an error if the decoding failed.
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func (s *ErasureStorage) ErasureDecodeDataBlocks(data [][]byte) error {
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if err := s.erasure.ReconstructData(data); err != nil {
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return errors.Tracef("failed to reconstruct data: %v", err)
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}
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return nil
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}
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// ErasureDecodeDataAndParityBlocks decodes the given erasure-coded data and verifies it.
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// It returns an error if the decoding failed.
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func (s *ErasureStorage) ErasureDecodeDataAndParityBlocks(data [][]byte) error {
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if err := s.erasure.Reconstruct(data); err != nil {
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return errors.Tracef("failed to reconstruct data: %v", err)
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}
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return nil
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}
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// NewBitrotVerifier returns a new BitrotVerifier implementing the given algorithm.
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func NewBitrotVerifier(algorithm BitrotAlgorithm, checksum []byte) *BitrotVerifier {
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return &BitrotVerifier{algorithm.New(), algorithm, checksum, false}
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}
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// BitrotVerifier can be used to verify protected data.
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type BitrotVerifier struct {
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hash.Hash
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algorithm BitrotAlgorithm
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sum []byte
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verified bool
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}
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// Verify returns true iff the computed checksum of the verifier matches the the checksum provided when the verifier
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// was created.
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func (v *BitrotVerifier) Verify() bool {
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v.verified = true
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return subtle.ConstantTimeCompare(v.Sum(nil), v.sum) == 1
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}
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// IsVerified returns true iff Verify was called at least once.
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func (v *BitrotVerifier) IsVerified() bool { return v.verified }
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