Shell: Implement redirections

This works well enough. At the moment redirections can appear anywhere
in the command **after** environment variables and possible alias
command. This means commands like `>foo echo hello` are not supported.
I don't think this is big enough problem for now (99% time redirections
are given after arguments) that i would rewrite the environment and
alias parsing.

userspace/programs/Shell/CommandTypes.h

@@ -2,7 +2,7 @@
 
 #include <BAN/String.h>
 
-#define COMMAND_GET_MACRO(_0, _1, _2, NAME, ...) NAME
+#define COMMAND_GET_MACRO(_0, _1, _2, _3, NAME, ...) NAME
 
 #define COMMAND_MOVE_0(class) \
 	class(class&& o) { } \
@@ -13,7 +13,10 @@
 #define COMMAND_MOVE_2(class, var1, var2) \
 	class(class&& o) { var1 = BAN::move(o.var1); var2 = BAN::move(o.var2); } \
 	class& operator=(class&& o) { var1 = BAN::move(o.var1); var2 = BAN::move(o.var2); return *this; }
-#define COMMAND_MOVE(class, ...) COMMAND_GET_MACRO(_0 __VA_OPT__(,) __VA_ARGS__, COMMAND_MOVE_2, COMMAND_MOVE_1, COMMAND_MOVE_0)(class, __VA_ARGS__)
+#define COMMAND_MOVE_3(class, var1, var2, var3) \
+	class(class&& o) { var1 = BAN::move(o.var1); var2 = BAN::move(o.var2); var3 = BAN::move(o.var3); } \
+	class& operator=(class&& o) { var1 = BAN::move(o.var1); var2 = BAN::move(o.var2); var3 = BAN::move(o.var3); return *this; }
+#define COMMAND_MOVE(class, ...) COMMAND_GET_MACRO(_0 __VA_OPT__(,) __VA_ARGS__, COMMAND_MOVE_3, COMMAND_MOVE_2, COMMAND_MOVE_1, COMMAND_MOVE_0)(class, __VA_ARGS__)
 
 #define COMMAND_RULE5(class, ...) \
 	class() = default; \
@@ -67,9 +70,19 @@ struct SingleCommand
 		CommandArgument value;
 	};
 
-	COMMAND_RULE5(SingleCommand, environment, arguments);
+	struct Redirection
+	{
+		CommandArgument destination;
+		int source_fd;
+		bool append;
+		bool duplicate;
+		bool input;
+	};
+
+	COMMAND_RULE5(SingleCommand, environment, arguments, redirections);
 	BAN::Vector<EnvironmentVariable> environment;
 	BAN::Vector<CommandArgument> arguments;
+	BAN::Vector<Redirection> redirections;
 };
 
 struct PipedCommand

userspace/programs/Shell/Execute.cpp

@@ -99,6 +99,47 @@ BAN::ErrorOr<Execute::ExecuteResult> Execute::execute_command_no_wait(const Inte
 		CHECK_FD_OR_PERROR_AND_EXIT(command.fd_in, STDIN_FILENO);
 		CHECK_FD_OR_PERROR_AND_EXIT(command.fd_out, STDOUT_FILENO);
 
+		for (const auto& redirection : command.redirections)
+		{
+			int dst_fd = -1;
+
+			if (redirection.duplicate)
+			{
+				if (!redirection.path.empty())
+				{
+					dst_fd = 0;
+
+					for (char ch : redirection.path)
+					{
+						if (!isdigit(ch))
+						{
+							dst_fd = -1;
+							break;
+						}
+
+						dst_fd = (dst_fd * 10) + (ch - '0');
+					}
+				}
+			}
+			else
+			{
+				const int flags = O_CREAT
+					| (redirection.input ? O_RDONLY : O_WRONLY)
+					| (redirection.append ? O_APPEND : O_TRUNC);
+				dst_fd = open(redirection.path.data(), flags, 0644);
+				if (dst_fd == -1)
+				{
+					perror("open");
+					exit(errno);
+				}
+			}
+
+			CHECK_FD_OR_PERROR_AND_EXIT(dst_fd, redirection.source_fd);
+
+			if (!redirection.duplicate)
+				close(dst_fd);
+		}
+
 		execv(command.command.get<BAN::String>().data(), const_cast<char* const*>(exec_args.data()));
 		perror("execv");
 		exit(errno);
@@ -125,6 +166,7 @@ BAN::ErrorOr<int> Execute::execute_command_sync(BAN::Span<const BAN::String> arg
 		.command = {},
 		.arguments = arguments,
 		.environments = {},
+		.redirections = {},
 		.fd_in = fd_in,
 		.fd_out = fd_out,
 		.background = false,
@@ -194,6 +236,22 @@ BAN::ErrorOr<void> Execute::execute_command(const PipedCommand& piped_command)
 			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");
@@ -221,11 +279,13 @@ BAN::ErrorOr<void> Execute::execute_command(const PipedCommand& piped_command)
 
 		const auto arguments = TRY_OR_PERROR_AND_BREAK(evaluate_arguments(piped_command.commands[i].arguments.span()));
 		const auto environments = TRY_OR_PERROR_AND_BREAK(evaluate_environment(piped_command.commands[i].environment.span()));
+		const auto redirections = TRY_OR_PERROR_AND_BREAK(evaluate_redirections(piped_command.commands[i].redirections.span()));
 
 		InternalCommand command {
 			.command = {},
 			.arguments = arguments.span(),
 			.environments = environments.span(),
+			.redirections = redirections.span(),
 			.fd_in = fd_in,
 			.fd_out = fd_out,
 			.background = piped_command.background,

userspace/programs/Shell/Execute.h

@@ -12,6 +12,7 @@ class Execute
 public:
 	Execute() = default;
 
+	// FIXME: remove this, this is only used by *builtin* time which should not be a builtin
 	BAN::ErrorOr<int> execute_command_sync(BAN::Span<const BAN::String> arguments, int fd_in, int fd_out);
 	BAN::ErrorOr<void> execute_command(const SingleCommand&, int fd_in, int fd_out, bool background, pid_t pgrp = 0);
 	BAN::ErrorOr<void> execute_command(const PipedCommand&);
@@ -39,9 +40,19 @@ private:
 			BAN::String value;
 		};
 
+		struct Redirection
+		{
+			BAN::String path;
+			int source_fd;
+			bool append;
+			bool duplicate;
+			bool input;
+		};
+
 		Command command;
 		BAN::Span<const BAN::String> arguments;
 		BAN::Span<const Environment> environments;
+		BAN::Span<Redirection> redirections;
 		int fd_in;
 		int fd_out;
 		bool background;

userspace/programs/Shell/Lexer.cpp

@@ -21,6 +21,8 @@ BAN::ErrorOr<BAN::Vector<Token>> tokenize_string(BAN::StringView string)
 				case ')':  return Token::Type::CloseParen;
 				case '$':  return Token::Type::Dollar;
 				case '"':  return Token::Type::DoubleQuote;
+				case '>':  return Token::Type::GreaterThan;
+				case '<':  return Token::Type::LessThan;
 				case '{':  return Token::Type::OpenCurly;
 				case '(':  return Token::Type::OpenParen;
 				case '|':  return Token::Type::Pipe;

userspace/programs/Shell/Token.cpp

@@ -27,6 +27,12 @@ void Token::debug_dump() const
 		case Type::DoubleQuote:
 			dprintln("Token <DoubleQuote>");
 			break;
+		case Type::GreaterThan:
+			dprintln("Token <GreaterThan>");
+			break;
+		case Type::LessThan:
+			dprintln("Token <LessThan>");
+			break;
 		case Type::OpenCurly:
 			dprintln("Token <OpenCurly>");
 			break;

userspace/programs/Shell/Token.h

@@ -19,6 +19,8 @@ public:
 		CloseParen,
 		Dollar,
 		DoubleQuote,
+		GreaterThan,
+		LessThan,
 		OpenCurly,
 		OpenParen,
 		Pipe,

userspace/programs/Shell/TokenParser.cpp

@@ -7,6 +7,7 @@
 #include <BAN/ScopeGuard.h>
 
 #include <stdio.h>
+#include <unistd.h>
 
 static constexpr bool can_parse_argument_from_token_type(Token::Type token_type)
 {
@@ -18,6 +19,8 @@ static constexpr bool can_parse_argument_from_token_type(Token::Type token_type)
 		case Token::Type::Ampersand:
 		case Token::Type::CloseCurly:
 		case Token::Type::CloseParen:
+		case Token::Type::GreaterThan:
+		case Token::Type::LessThan:
 		case Token::Type::OpenCurly:
 		case Token::Type::OpenParen:
 		case Token::Type::Pipe:
@@ -43,6 +46,8 @@ static constexpr char token_type_to_single_character(Token::Type type)
 		case Token::Type::CloseParen:  return ')';
 		case Token::Type::Dollar:      return '$';
 		case Token::Type::DoubleQuote: return '"';
+		case Token::Type::GreaterThan: return '>';
+		case Token::Type::LessThan:    return '<';
 		case Token::Type::OpenCurly:   return '{';
 		case Token::Type::OpenParen:   return '(';
 		case Token::Type::Pipe:        return '|';
@@ -74,6 +79,10 @@ static constexpr BAN::Error unexpected_token_error(Token::Type type)
 			return BAN::Error::from_literal("unexpected token $");
 		case Token::Type::DoubleQuote:
 			return BAN::Error::from_literal("unexpected token \"");
+		case Token::Type::GreaterThan:
+			return BAN::Error::from_literal("unexpected token >");
+		case Token::Type::LessThan:
+			return BAN::Error::from_literal("unexpected token <");
 		case Token::Type::OpenCurly:
 			return BAN::Error::from_literal("unexpected token {");
 		case Token::Type::Pipe:
@@ -185,6 +194,8 @@ BAN::ErrorOr<CommandArgument::ArgumentPart> TokenParser::parse_backslash(bool is
 		case Token::Type::CloseParen:
 		case Token::Type::Dollar:
 		case Token::Type::DoubleQuote:
+		case Token::Type::GreaterThan:
+		case Token::Type::LessThan:
 		case Token::Type::OpenCurly:
 		case Token::Type::OpenParen:
 		case Token::Type::Pipe:
@@ -277,6 +288,8 @@ BAN::ErrorOr<CommandArgument::ArgumentPart> TokenParser::parse_dollar()
 		case Token::Type::CloseCurly:
 		case Token::Type::CloseParen:
 		case Token::Type::DoubleQuote:
+		case Token::Type::GreaterThan:
+		case Token::Type::LessThan:
 		case Token::Type::Pipe:
 		case Token::Type::Semicolon:
 		case Token::Type::SingleQuote:
@@ -363,6 +376,8 @@ BAN::ErrorOr<CommandArgument::ArgumentPart> TokenParser::parse_single_quote()
 			case Token::Type::CloseParen:
 			case Token::Type::Dollar:
 			case Token::Type::DoubleQuote:
+			case Token::Type::GreaterThan:
+			case Token::Type::LessThan:
 			case Token::Type::OpenCurly:
 			case Token::Type::OpenParen:
 			case Token::Type::Pipe:
@@ -403,6 +418,8 @@ BAN::ErrorOr<CommandArgument> TokenParser::parse_argument()
 			case Token::Type::Ampersand:
 			case Token::Type::CloseCurly:
 			case Token::Type::CloseParen:
+			case Token::Type::GreaterThan:
+			case Token::Type::LessThan:
 			case Token::Type::OpenCurly:
 			case Token::Type::OpenParen:
 			case Token::Type::Pipe:
@@ -466,6 +483,56 @@ BAN::ErrorOr<CommandArgument> TokenParser::parse_argument()
 	return result;
 }
 
+BAN::ErrorOr<SingleCommand::Redirection> TokenParser::parse_redirection()
+{
+	int source_fd = -1;
+
+	if (peek_token().type() == Token::Type::String)
+	{
+		const auto string = read_token().string();
+
+		source_fd = 0;
+		for (char ch : string)
+			source_fd = (source_fd * 10) + (ch - '0');
+	}
+
+	const auto token_type = peek_token().type();
+	consume_token();
+
+	switch (token_type)
+	{
+		case Token::Type::GreaterThan:
+			if (source_fd == -1)
+				source_fd = STDOUT_FILENO;
+			break;
+		case Token::Type::LessThan:
+			if (source_fd == -1)
+				source_fd = STDIN_FILENO;
+			break;
+		default:
+			ASSERT_NOT_REACHED();
+	}
+
+	const bool append = (peek_token().type() == token_type);
+	if (append)
+		consume_token();
+
+	const bool duplicate = (peek_token().type() == Token::Type::Ampersand);
+	if (duplicate)
+		consume_token();
+
+	while (peek_token().type() == Token::Type::Whitespace)
+		consume_token();
+
+	return SingleCommand::Redirection {
+		.destination = TRY(parse_argument()),
+		.source_fd = source_fd,
+		.append = append,
+		.duplicate = duplicate,
+		.input = (token_type == Token::Type::LessThan),
+	};
+}
+
 BAN::ErrorOr<SingleCommand> TokenParser::parse_single_command()
 {
 	SingleCommand result;
@@ -527,6 +594,8 @@ BAN::ErrorOr<SingleCommand> TokenParser::parse_single_command()
 			case Token::Type::CloseCurly:
 			case Token::Type::Dollar:
 			case Token::Type::DoubleQuote:
+			case Token::Type::GreaterThan:
+			case Token::Type::LessThan:
 			case Token::Type::OpenCurly:
 			case Token::Type::OpenParen:
 			case Token::Type::SingleQuote:
@@ -562,18 +631,56 @@ BAN::ErrorOr<SingleCommand> TokenParser::parse_single_command()
 			consume_token();
 	}
 
+	const auto can_parse_redirection =
+		[this]() -> bool
+		{
+			const auto& token = peek_token();
+
+			if (token.type() == Token::Type::GreaterThan)
+				return true;
+			if (token.type() == Token::Type::LessThan)
+				return true;
+			if (token.type() != Token::Type::String)
+				return false;
+			if (token.string().empty())
+				return false;
+
+			bool is_number = true;
+			for (size_t i = 0; i < token.string().size() && is_number; i++)
+				is_number = isdigit(token.string()[i]);
+			if (!is_number)
+				return false;
+
+			auto temp = read_token();
+			const bool is_redir =
+				(peek_token().type() == Token::Type::GreaterThan) ||
+				(peek_token().type() == Token::Type::LessThan);
+			MUST(unget_token(BAN::move(temp)));
+			if (!is_redir)
+				return false;
+
+			return true;
+		};
+
 	while (peek_token().type() != Token::Type::EOF_)
 	{
 		while (peek_token().type() == Token::Type::Whitespace)
 			consume_token();
 
-		auto argument = TRY(parse_argument());
-		TRY(result.arguments.push_back(BAN::move(argument)));
-
-		while (peek_token().type() == Token::Type::Whitespace)
-			consume_token();
-		if (!can_parse_argument_from_token_type(peek_token().type()))
+		if (can_parse_redirection())
+		{
+			auto redirection = TRY(parse_redirection());
+			TRY(result.redirections.push_back(BAN::move(redirection)));
+		}
+		else if (can_parse_argument_from_token_type(peek_token().type()))
+		{
+			auto argument = TRY(parse_argument());
+			TRY(result.arguments.push_back(BAN::move(argument)));
+		}
+		else
+		{
 			break;
+		}
 	}
 
 	return result;

userspace/programs/Shell/TokenParser.h

@@ -44,6 +44,8 @@ private:
 	BAN::ErrorOr<CommandArgument::ArgumentPart> parse_single_quote();
 	BAN::ErrorOr<CommandArgument> parse_argument();
 
+	BAN::ErrorOr<SingleCommand::Redirection> parse_redirection();
+
 	BAN::ErrorOr<SingleCommand> parse_single_command();
 	BAN::ErrorOr<PipedCommand> parse_piped_command();
 	BAN::ErrorOr<CommandTree> parse_command_tree();