112 lines
2.9 KiB
Go
112 lines
2.9 KiB
Go
/*
|
|
* Minio Cloud Storage, (C) 2016 Minio, Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
package cmd
|
|
|
|
import (
|
|
"bytes"
|
|
"context"
|
|
"io"
|
|
|
|
"github.com/klauspost/reedsolomon"
|
|
"github.com/minio/minio/cmd/logger"
|
|
)
|
|
|
|
// getDataBlockLen - get length of data blocks from encoded blocks.
|
|
func getDataBlockLen(enBlocks [][]byte, dataBlocks int) int {
|
|
size := 0
|
|
// Figure out the data block length.
|
|
for _, block := range enBlocks[:dataBlocks] {
|
|
size += len(block)
|
|
}
|
|
return size
|
|
}
|
|
|
|
// Writes all the data blocks from encoded blocks until requested
|
|
// outSize length. Provides a way to skip bytes until the offset.
|
|
func writeDataBlocks(ctx context.Context, dst io.Writer, enBlocks [][]byte, dataBlocks int, offset int64, length int64) (int64, error) {
|
|
// Offset and out size cannot be negative.
|
|
if offset < 0 || length < 0 {
|
|
logger.LogIf(ctx, errUnexpected)
|
|
return 0, errUnexpected
|
|
}
|
|
|
|
// Do we have enough blocks?
|
|
if len(enBlocks) < dataBlocks {
|
|
logger.LogIf(ctx, reedsolomon.ErrTooFewShards)
|
|
return 0, reedsolomon.ErrTooFewShards
|
|
}
|
|
|
|
// Do we have enough data?
|
|
if int64(getDataBlockLen(enBlocks, dataBlocks)) < length {
|
|
logger.LogIf(ctx, reedsolomon.ErrShortData)
|
|
return 0, reedsolomon.ErrShortData
|
|
}
|
|
|
|
// Counter to decrement total left to write.
|
|
write := length
|
|
|
|
// Counter to increment total written.
|
|
var totalWritten int64
|
|
|
|
// Write all data blocks to dst.
|
|
for _, block := range enBlocks[:dataBlocks] {
|
|
// Skip blocks until we have reached our offset.
|
|
if offset >= int64(len(block)) {
|
|
// Decrement offset.
|
|
offset -= int64(len(block))
|
|
continue
|
|
} else {
|
|
// Skip until offset.
|
|
block = block[offset:]
|
|
|
|
// Reset the offset for next iteration to read everything
|
|
// from subsequent blocks.
|
|
offset = 0
|
|
}
|
|
// We have written all the blocks, write the last remaining block.
|
|
if write < int64(len(block)) {
|
|
n, err := io.Copy(dst, bytes.NewReader(block[:write]))
|
|
if err != nil {
|
|
if err != io.ErrClosedPipe {
|
|
logger.LogIf(ctx, err)
|
|
}
|
|
return 0, err
|
|
}
|
|
totalWritten += n
|
|
break
|
|
}
|
|
// Copy the block.
|
|
n, err := io.Copy(dst, bytes.NewReader(block))
|
|
if err != nil {
|
|
// The writer will be closed incase of range queries, which will emit ErrClosedPipe.
|
|
if err != io.ErrClosedPipe {
|
|
logger.LogIf(ctx, err)
|
|
}
|
|
return 0, err
|
|
}
|
|
|
|
// Decrement output size.
|
|
write -= n
|
|
|
|
// Increment written.
|
|
totalWritten += n
|
|
}
|
|
|
|
// Success.
|
|
return totalWritten, nil
|
|
}
|