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73 lines
1.4 KiB
73 lines
1.4 KiB
package buffer
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"github.com/djherbis/buffer/wrapio"
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)
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// File is used as the backing resource for a the NewFile BufferAt.
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type File interface {
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Name() string
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Stat() (fi os.FileInfo, err error)
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io.ReaderAt
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io.WriterAt
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Close() error
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}
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type fileBuffer struct {
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file File
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*wrapio.Wrapper
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}
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// NewFile returns a new BufferAt backed by "file" with max-size N.
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func NewFile(N int64, file File) BufferAt {
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return &fileBuffer{
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file: file,
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Wrapper: wrapio.NewWrapper(file, 0, 0, N),
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}
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}
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func init() {
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gob.Register(&fileBuffer{})
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}
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func (buf *fileBuffer) MarshalBinary() ([]byte, error) {
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fullpath, err := filepath.Abs(filepath.Dir(buf.file.Name()))
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if err != nil {
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return nil, err
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}
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base := filepath.Base(buf.file.Name())
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buf.file.Close()
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buffer := bytes.NewBuffer(nil)
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fmt.Fprintln(buffer, filepath.Join(fullpath, base))
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fmt.Fprintln(buffer, buf.Wrapper.N, buf.Wrapper.L, buf.Wrapper.O)
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return buffer.Bytes(), nil
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}
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func (buf *fileBuffer) UnmarshalBinary(data []byte) error {
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buffer := bytes.NewBuffer(data)
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var filename string
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var N, L, O int64
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_, err := fmt.Fscanln(buffer, &filename)
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if err != nil {
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return err
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}
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file, err := os.Open(filename)
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if err != nil {
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return err
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}
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buf.file = file
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_, err = fmt.Fscanln(buffer, &N, &L, &O)
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buf.Wrapper = wrapio.NewWrapper(file, L, O, N)
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return err
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}
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