Seek() in archive file

[nicola-spb]

Hello,

When i walking in archive I have fs.File (without Seek()). How can I get ReadSeeker interface of it?

fsys, err := archiver.FileSystem(sourcePath)
if err != nil {
	return nil, err
}
	
err = fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
	if err != nil {
		return err
	}

	f, err := fsys.Open(path)
	if err != nil {
		return err
	}
	defer f.Close()
	
	frs := f.(io.ReadSeeker)  // Error
}

Thanks

[mholt]

I don't think the underlying archive format implementations (tar, zip, etc) give us Seek(), sorry.

It does seem like that should be able to work when dealing with regular files on disk, but this might be a feature request more for the standard library (or whatever package implements the underlying archive format).

Will close this, but feel free to continue discussion. I could very well be wrong.

[oliverpool]

I tried to implement a caddy module after the merge of caddyserver/caddy#4909 but it panics because of this:

http.stdlib	http: panic serving 127.0.0.1:46708: interface conversion: archiver.extractedFile is not io.ReadSeeker: missing method Seek

[oliverpool]

https://github.com/nlepage/go-tarfs works fine ! (since nlepage/go-tarfs#4)

[oliverpool]

I just realized, that it reads the whole file in memory: https://github.com/nlepage/go-tarfs/blob/bec76bb13b0a3be9e1bf8bb03141a6d26ce91902/fs.go#L39-L44 ...

[mholt]

@oliverpool

I tried to implement a caddy module after the merge of caddyserver/caddy#4909 but it panics because of this:

Gah, I forgot about that.

I just realized, that it reads the whole file in memory: nlepage/go-tarfs@bec76bb/fs.go#L39-L44 ...

Yikes, haha. That probably won't do for production use. Thanks for experimenting with it!!