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102 lines
2.6 KiB
Go
102 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 memory-only implementation of Filer.
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package lldb
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import (
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"fmt"
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"io"
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"github.com/cznic/internal/file"
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)
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var _ Filer = &MemFiler{}
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// MemFiler is a memory backed Filer. It implements BeginUpdate, EndUpdate and
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// Rollback as no-ops. MemFiler is not automatically persistent, but it has
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// ReadFrom and WriteTo methods.
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type MemFiler struct {
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fi file.Interface
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nest int
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}
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// NewMemFiler returns a new MemFiler.
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func NewMemFiler() *MemFiler {
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fi, err := file.OpenMem("")
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if err != nil {
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return nil
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}
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return &MemFiler{fi: fi}
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}
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// BeginUpdate implements Filer.
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func (f *MemFiler) 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 *MemFiler) 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 *MemFiler) 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 *MemFiler) Name() string { return fmt.Sprintf("%p.memfiler", f) }
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// PunchHole implements Filer.
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func (f *MemFiler) PunchHole(off, size int64) (err error) { return nil }
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// ReadAt implements Filer.
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func (f *MemFiler) ReadAt(b []byte, off int64) (n int, err error) { return f.fi.ReadAt(b, off) }
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// ReadFrom is a helper to populate MemFiler's content from r. 'n' reports the
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// number of bytes read from 'r'.
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func (f *MemFiler) ReadFrom(r io.Reader) (n int64, err error) { return f.fi.ReadFrom(r) }
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// Rollback implements Filer.
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func (f *MemFiler) Rollback() (err error) { return nil }
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// Size implements Filer.
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func (f *MemFiler) 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 *MemFiler) Sync() error { return nil }
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// Truncate implements Filer.
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func (f *MemFiler) Truncate(size int64) (err error) { return f.fi.Truncate(size) }
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// WriteAt implements Filer.
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func (f *MemFiler) WriteAt(b []byte, off int64) (n int, err error) { return f.fi.WriteAt(b, off) }
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// WriteTo is a helper to copy/persist MemFiler's content to w. If w is also
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// an io.WriterAt then WriteTo may attempt to _not_ write any big, for some
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// value of big, runs of zeros, i.e. it will attempt to punch holes, where
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// possible, in `w` if that happens to be a freshly created or to zero length
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// truncated OS file. 'n' reports the number of bytes written to 'w'.
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func (f *MemFiler) WriteTo(w io.Writer) (n int64, err error) { return f.fi.WriteTo(w) }
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