Function async_run

test/setup_transfer.cpp:540–603

returns 0 on failure, otherwise pid

// returns 0 on failure, otherwise pid
pid_type async_run(char const* cmdline)
{
#ifdef _WIN32
	char buf[2048];
	std::snprintf(buf, sizeof(buf), "%s", cmdline);

	std::printf("CreateProcess %s\n", buf);
	PROCESS_INFORMATION pi;
	STARTUPINFOA startup{};
	startup.cb = sizeof(startup);
	startup.dwFlags = STARTF_USESTDHANDLES;
	startup.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
	startup.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
	startup.hStdError = GetStdHandle(STD_OUTPUT_HANDLE);
	int const ret = CreateProcessA(nullptr, buf, nullptr, nullptr, TRUE
		, 0, nullptr, nullptr, &startup, &pi);

	if (ret == 0)
	{
		int const error = GetLastError();
		std::printf("ERROR: (%d) %s\n", error, error_code(error, system_category()).message().c_str());
		return 0;
	}

	DWORD len = sizeof(buf);
	if (QueryFullProcessImageNameA(pi.hProcess, PROCESS_NAME_NATIVE, buf, &len) == 0)
	{
		int const error = GetLastError();
		std::printf("ERROR: QueryFullProcessImageName (%d) %s\n", error
			, error_code(error, system_category()).message().c_str());
	}
	else
	{
		std::printf("launched: %s\n", buf);
	}
	return pi.dwProcessId;
#else
	pid_type p;
	char arg_storage[4096];
	char* argp = arg_storage;
	std::vector<char*> argv;
	argv.push_back(argp);
	for (char const* in = cmdline; *in != '\0'; ++in)
	{
		if (*in != ' ')
		{
			*argp++ = *in;
			continue;
		}
		*argp++ = '\0';
		argv.push_back(argp);
	}
	*argp = '\0';
	argv.push_back(nullptr);

	int ret = posix_spawnp(&p, argv[0], nullptr, nullptr, &argv[0], nullptr);
	if (ret != 0)
	{