mirror of
https://github.com/octoleo/syncthing.git
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100 lines
2.6 KiB
Go
100 lines
2.6 KiB
Go
// Copyright 2014 The lldb Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// A basic os.File backed Filer.
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package lldb
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import (
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"os"
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"github.com/cznic/internal/file"
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)
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var _ Filer = &SimpleFileFiler{}
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// SimpleFileFiler is an os.File backed Filer intended for use where structural
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// consistency can be reached by other means (SimpleFileFiler is for example
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// wrapped in eg. an RollbackFiler or ACIDFiler0) or where persistence is not
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// required (temporary/working data sets).
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//
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// SimpleFileFiler is the most simple os.File backed Filer implementation as it
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// does not really implement BeginUpdate and EndUpdate/Rollback in any way
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// which would protect the structural integrity of data. If misused e.g. as a
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// real database storage w/o other measures, it can easily cause data loss
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// when, for example, a power outage occurs or the updating process terminates
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// abruptly.
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type SimpleFileFiler struct {
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fi file.Interface
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name string
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nest int
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}
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// NewSimpleFileFiler returns a new SimpleFileFiler.
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func NewSimpleFileFiler(f *os.File) *SimpleFileFiler {
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fi, err := file.Open(f)
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if err != nil {
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return nil
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}
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sf := &SimpleFileFiler{fi: fi, name: f.Name()}
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return sf
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}
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// BeginUpdate implements Filer.
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func (f *SimpleFileFiler) BeginUpdate() error {
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f.nest++
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return nil
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}
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// Close implements Filer.
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func (f *SimpleFileFiler) Close() (err error) {
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if f.nest != 0 {
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return &ErrPERM{(f.Name() + ":Close")}
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}
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return f.fi.Close()
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}
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// EndUpdate implements Filer.
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func (f *SimpleFileFiler) EndUpdate() (err error) {
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if f.nest == 0 {
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return &ErrPERM{(f.Name() + ":EndUpdate")}
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}
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f.nest--
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return
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}
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// Name implements Filer.
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func (f *SimpleFileFiler) Name() string { return f.name }
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// PunchHole implements Filer.
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func (f *SimpleFileFiler) PunchHole(off, size int64) (err error) { return nil }
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// ReadAt implements Filer.
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func (f *SimpleFileFiler) ReadAt(b []byte, off int64) (n int, err error) { return f.fi.ReadAt(b, off) }
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// Rollback implements Filer.
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func (f *SimpleFileFiler) Rollback() (err error) { return nil }
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// Size implements Filer.
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func (f *SimpleFileFiler) Size() (int64, error) {
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info, err := f.fi.Stat()
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if err != nil {
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return 0, err
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}
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return info.Size(), nil
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}
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// Sync implements Filer.
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func (f *SimpleFileFiler) Sync() error { return f.fi.Sync() }
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// Truncate implements Filer.
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func (f *SimpleFileFiler) Truncate(size int64) (err error) { return f.fi.Truncate(size) }
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// WriteAt implements Filer.
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func (f *SimpleFileFiler) WriteAt(b []byte, off int64) (n int, err error) { return f.fi.WriteAt(b, off) }
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