/**
 * runs a callback in a vforked child process that shares its address space with
 * the current process. the child behaves much like a thread as a result and the
 * callback must not make changes to process memory that we cannot undo from the
 * parent, otherwise we may leak memory or fully trash the parent address space.
 *
 * NOTE: see `asVFork` for safety information regarding credentials and signals.
 *
 * throws an exception if the child exec's or otherwise doesn't return a result.
 */
static auto inVFork(int flags, auto fn)
{
    auto [pid, result] = asVFork(flags, fn);

    if (result) {
        return std::move(result->value());
    } else {
        throw Error("vfork child unexpectedly did not produce a value");
    }
}

this is the entrypoint of the magic

In reply to @lunaphied:lunaphied.me
I think there were a few CLs on the Gerrit but nothing being actively worked

• how do people feel about the existing test suite that comes along with nix source code or Lix?

1. gtest (offer only available in libexpr and libutil)

2. bash script

3. virtual machine