trailer := string(b.toSTAR().trailer())
	switch {
	case magic == magicUSTAR && trailer == trailerSTAR:
		return formatSTAR
	case magic == magicUSTAR:
		return FormatUSTAR | FormatPAX
	case magic == magicGNU && version == versionGNU:
		return FormatGNU
	default:
		return formatV7
	}
}

// setFormat writes the magic values necessary for specified format
// and then updates the checksum accordingly.

}

func TestZip64EdgeCase(t *testing.T) {
	if testing.Short() {
		t.Skip("slow test; skipping")
	}
	t.Parallel()
	// Test a zip file with uncompressed size 0xFFFFFFFF.
	// That's the magic marker for a 64-bit file, so even though
	// it fits in a 32-bit field we must use the 64-bit field.
	// Go 1.5 and earlier got this wrong,
	// writing an invalid zip file.