// To be called exactly twice by the parent process
static <T> T rendezvousParent(Process p, Callable<T> callable) throws Throwable {
p.getInputStream().read();
T result = callable.call();
OutputStream os = p.getOutputStream();
os.write((byte) '\n');
os.flush();
return result;
}
static String outputOf(final Process p) {
try {
Future<String> outputFuture = futureOutputOf(p.getInputStream());
Future<String> errorFuture = futureOutputOf(p.getErrorStream());
final String output = outputFuture.get();
final String error = errorFuture.get();
// Check for successful process completion
equal(error, "");
equal(p.waitFor(), 0);
equal(p.exitValue(), 0);
return output;
} catch (Throwable t) {
unexpected(t);
throw new Error(t);
}
}