CODEWITHSUNDEEP
go
Jeff
Jeff

Reputation: 7210

Golang un-gzip from bytes.Reader

I have a file struct that holds a body which is just a *bytes.Reader I have two methods on the struct Zip() error and UnZip() error. When I call Zip it should zip the file storing the zipped data in body and I should be able to call UnZip on the same file and store the unzipped data in the body.

The minimal example I have is below in the playground. https://play.golang.org/p/WmZtqtvnyN

I'm able to zip the file just fine and looks like it's doing what it's supposed to do; however, when I try and unzip the file I get unexpected EOF

I've been going at this for hours now. Any help is greatly appreciated.

Upvotes: 2

Views: 2671

Answers (2)

Seva
Seva

Reputation: 2488

I believe you should close gzip writer before geting bytes from the underlying buffer.

func (f *File) Zip() error {
    buff := bytes.NewBuffer(nil)

    writer := gzip.NewWriter(buff)
    defer writer.Close()

    _, err := f.Body.WriteTo(writer)
    if err != nil {
        return err
    }

    writer.Close() // I have added this line

    f.Body = bytes.NewReader(buff.Bytes())
    f.Name = fmt.Sprintf("%s.gz", f.Name)
    return nil
}

Upvotes: 2

Venkat
Venkat

Reputation: 1145

As per the documentation for gzip.NewReader, If r does not also implement io.ByteReader, the decompressor may read more data than necessary from r.

For bytes.Reader, A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker, io.ByteScanner, and io.RuneScanner interfaces by reading from a byte slice.

The problem maybe lies in the fact that bytes.Reader does not implement io.ByteReader.

Upvotes: 0

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