// Copyright (c) 2015-2021 MinIO, Inc.//// This file is part of MinIO Object Storage stack//// This program is free software: you can redistribute it and/or modify// it under the terms of the GNU Affero General Public License as published by// the Free Software Foundation, either version 3 of the License, or// (at your option) any later version.//// This program is distributed in the hope that it will be useful// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the// GNU Affero General Public License for more details.//// You should have received a copy of the GNU Affero General Public License// along with this program.  If not, see <http://www.gnu.org/licenses/>. package cmd import (	"bytes"	"context"	"crypto/rand"	"io"	"testing") var erasureEncodeDecodeTests = []struct {	dataBlocks, parityBlocks   int	missingData, missingParity int	reconstructParity          bool	shouldFail                 bool}{	{dataBlocks: 2, parityBlocks: 2, missingData: 0, missingParity: 0, reconstructParity: true, shouldFail: false},	{dataBlocks: 3, parityBlocks: 3, missingData: 1, missingParity: 0, reconstructParity: true, shouldFail: false},	{dataBlocks: 4, parityBlocks: 4, missingData: 2, missingParity: 0, reconstructParity: false, shouldFail: false},	{dataBlocks: 5, parityBlocks: 5, missingData: 0, missingParity: 1, reconstructParity: true, shouldFail: false},	{dataBlocks: 6, parityBlocks: 6, missingData: 0, missingParity: 2, reconstructParity: true, shouldFail: false},	{dataBlocks: 7, parityBlocks: 7, missingData: 1, missingParity: 1, reconstructParity: false, shouldFail: false},	{dataBlocks: 8, parityBlocks: 8, missingData: 3, missingParity: 2, reconstructParity: false, shouldFail: false},	{dataBlocks: 2, parityBlocks: 2, missingData: 2, missingParity: 1, reconstructParity: true, shouldFail: true},	{dataBlocks: 4, parityBlocks: 2, missingData: 2, missingParity: 2, reconstructParity: false, shouldFail: true},	{dataBlocks: 8, parityBlocks: 4, missingData: 2, missingParity: 2, reconstructParity: false, shouldFail: false},} func TestErasureEncodeDecode(t *testing.T) {	data := make([]byte, 256)	if _, err := io.ReadFull(rand.Reader, data); err != nil {		t.Fatalf("Failed to read random data: %v", err)	}	for i, test := range erasureEncodeDecodeTests {		buffer := make([]byte, len(data), 2*len(data))		copy(buffer, data) 		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.parityBlocks, blockSizeV2)		if err != nil {			t.Fatalf("Test %d: failed to create erasure: %v", i, err)		}		encoded, err := erasure.EncodeData(context.Background(), buffer)		if err != nil {			t.Fatalf("Test %d: failed to encode data: %v", i, err)		} 		for j := range encoded[:test.missingData] {			encoded[j] = nil		}		for j := test.dataBlocks; j < test.dataBlocks+test.missingParity; j++ {			encoded[j] = nil		} 		if test.reconstructParity {			err = erasure.DecodeDataAndParityBlocks(context.Background(), encoded)		} else {			err = erasure.DecodeDataBlocks(encoded)		} 		if err == nil && test.shouldFail {			t.Errorf("Test %d: test should fail but it passed", i)		}		if err != nil && !test.shouldFail {			t.Errorf("Test %d: test should pass but it failed: %v", i, err)		} 		decoded := encoded		if !test.shouldFail {			if test.reconstructParity {				for j := range decoded {					if decoded[j] == nil {						t.Errorf("Test %d: failed to reconstruct shard %d", i, j)					}				}			} else {				for j := range decoded[:test.dataBlocks] {					if decoded[j] == nil {						t.Errorf("Test %d: failed to reconstruct data shard %d", i, j)					}				}			} 			decodedData := new(bytes.Buffer)			if _, err = writeDataBlocks(context.Background(), decodedData, decoded, test.dataBlocks, 0, int64(len(data))); err != nil {				t.Errorf("Test %d: failed to write data blocks: %v", i, err)			}			if !bytes.Equal(decodedData.Bytes(), data) {				t.Errorf("Test %d: Decoded data does not match original data: got: %v want: %v", i, decodedData.Bytes(), data)			}		}	}} // Setup for erasureCreateFile and erasureReadFile tests.type erasureTestSetup struct {	dataBlocks   int	parityBlocks int	blockSize    int64	diskPaths    []string	disks        []StorageAPI} // Returns an initialized setup for erasure tests.func newErasureTestSetup(tb testing.TB, dataBlocks int, parityBlocks int, blockSize int64) (*erasureTestSetup, error) {	diskPaths := make([]string, dataBlocks+parityBlocks)	disks := make([]StorageAPI, len(diskPaths))	var err error	for i := range diskPaths {		disks[i], diskPaths[i], err = newXLStorageTestSetup(tb)		if err != nil {			return nil, err		}		err = disks[i].MakeVol(context.Background(), "testbucket")		if err != nil {			return nil, err		}	}	return &erasureTestSetup{dataBlocks, parityBlocks, blockSize, diskPaths, disks}, nil}