Function wrapUserFile

pkg/oci/spec_opts.go:1893–1911

wrapUserFile rejects non-regular sources and returns an fs.File that errors out if more than maxUserFileBytes are read from it.

(f fs.File, name string)

// wrapUserFile rejects non-regular sources and returns an fs.File that
// errors out if more than maxUserFileBytes are read from it.
func wrapUserFile(f fs.File, name string) (fs.File, error) {
	info, err := f.Stat()
	if err != nil {
		f.Close()
		return nil, fmt.Errorf("stat %s: %w", name, err)
	}
	if !info.Mode().IsRegular() {
		f.Close()
		return nil, fmt.Errorf("%s is not a regular file", name)
	}
	return &limitedFile{
		File: f,
		// Allow one byte past the cap so an overflow surfaces as an
		// error rather than a silent EOF that the parser would treat as
		// a clean end-of-file (and miss any entries past the cap).
		r:    &io.LimitedReader{R: f, N: maxUserFileBytes + 1},
		name: name,
	}, nil
}

// limitedFile is an fs.File whose Read returns an error once more than
// maxUserFileBytes have been read.