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55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
// Copyright 2015 The etcd Authors
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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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package fileutil
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import (
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"io"
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"os"
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)
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// Preallocate tries to allocate the space for given
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// file. This operation is only supported on linux by a
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// few filesystems (btrfs, ext4, etc.).
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// If the operation is unsupported, no error will be returned.
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// Otherwise, the error encountered will be returned.
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func Preallocate(f *os.File, sizeInBytes int64, extendFile bool) error {
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if sizeInBytes == 0 {
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// fallocate will return EINVAL if length is 0; skip
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return nil
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}
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if extendFile {
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return preallocExtend(f, sizeInBytes)
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}
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return preallocFixed(f, sizeInBytes)
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}
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func preallocExtendTrunc(f *os.File, sizeInBytes int64) error {
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curOff, err := f.Seek(0, io.SeekCurrent)
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if err != nil {
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return err
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}
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size, err := f.Seek(sizeInBytes, io.SeekEnd)
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if err != nil {
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return err
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}
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if _, err = f.Seek(curOff, io.SeekStart); err != nil {
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return err
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}
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if sizeInBytes > size {
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return nil
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}
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return f.Truncate(sizeInBytes)
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}
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