Function readFileHeader

fs.go:1940–1994

(f io.Reader, compressed bool, fileEncoding string)

}

func readFileHeader(f io.Reader, compressed bool, fileEncoding string) ([]byte, error) {
	r := f
	var (
		br  *brotli.Reader
		zr  *gzip.Reader
		zsr *zstd.Decoder
	)
	if compressed {
		var err error
		switch fileEncoding {
		case "br":
			if br, err = acquireBrotliReader(f); err != nil {
				return nil, err
			}
			r = br
		case "gzip":
			if zr, err = acquireGzipReader(f); err != nil {
				return nil, err
			}
			r = zr
		case "zstd":
			if zsr, err = acquireZstdReader(f); err != nil {
				return nil, err
			}
			r = zsr
		}
	}

	lr := &io.LimitedReader{
		R: r,
		N: 512,
	}
	data, err := io.ReadAll(lr)
	seeker, ok := f.(io.Seeker)
	if !ok {
		return nil, errors.New("must implement io.Seeker")
	}
	if _, err := seeker.Seek(0, io.SeekStart); err != nil {
		return nil, err
	}

	if br != nil {
		releaseBrotliReader(br)
	}

	if zr != nil {
		releaseGzipReader(zr)
	}

	if zsr != nil {
		releaseZstdReader(zsr)
	}

	return data, err
}

func stripLeadingSlashes(path []byte, stripSlashes int) []byte {
	for stripSlashes > 0 && len(path) > 0 {