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54 lines
1.5 KiB
54 lines
1.5 KiB
// 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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