Method execute_command

userspace/programs/Shell/Execute.cpp:207–363

}

BAN::ErrorOr<void> Execute::execute_command(const PipedCommand& piped_command)
{
	ASSERT(!piped_command.commands.empty());

	int last_pipe_rd = STDIN_FILENO;

	BAN::Vector<pid_t> child_pids;
	TRY(child_pids.resize(piped_command.commands.size(), 0));

	BAN::Vector<int> child_codes;
	TRY(child_codes.resize(piped_command.commands.size(), 126));

	const auto evaluate_arguments =
		[this](BAN::Span<const CommandArgument> arguments) -> BAN::ErrorOr<BAN::Vector<BAN::String>>
		{
			BAN::Vector<BAN::String> result;
			TRY(result.reserve(arguments.size()));
			for (const auto& argument : arguments)
				TRY(result.push_back(TRY(argument.evaluate(*this))));
			return result;
		};

	const auto evaluate_environment =
		[this](BAN::Span<const SingleCommand::EnvironmentVariable> environments) -> BAN::ErrorOr<BAN::Vector<InternalCommand::Environment>>
		{
			BAN::Vector<InternalCommand::Environment> result;
			TRY(result.reserve(environments.size()));
			for (const auto& environment : environments)
				TRY(result.emplace_back(environment.name, TRY(environment.value.evaluate(*this))));
			return result;
		};

	const auto evaluate_redirections =
		[this](BAN::Span<const SingleCommand::Redirection> redirections) -> BAN::ErrorOr<BAN::Vector<InternalCommand::Redirection>>
		{
			BAN::Vector<InternalCommand::Redirection> result;
			TRY(result.reserve(redirections.size()));
			for (const auto& redirection : redirections)
				TRY(result.push_back({
					.path = TRY(redirection.destination.evaluate(*this)),
					.source_fd = redirection.source_fd,
					.append = redirection.append,
					.duplicate = redirection.duplicate,
					.input = redirection.input,
				}));
			return result;
		};

	const int stdin_flags = fcntl(STDIN_FILENO, F_GETFL);
	if (stdin_flags == -1)
		perror("fcntl");

	for (size_t i = 0; i < piped_command.commands.size(); i++)
	{
		int new_pipe[2] { STDIN_FILENO, STDOUT_FILENO };
		if (i != piped_command.commands.size() - 1)
			if (pipe(new_pipe) == -1)
				return BAN::Error::from_errno(errno);