mpw-shell/command.cpp

#include "command.h"
#include "phase2-parser.h"
#include "environment.h"
#include "fdset.h"
#include "builtins.h"
#include "mpw-shell.h"
#include "error.h"

#include <stdexcept>
#include <unordered_map>
#include <cctype>
#include <cerrno>
#include <cstdlib>

#include "cxx/filesystem.h"
#include "cxx/string_splitter.h"

#include <unistd.h>
#include <sys/wait.h>
#include <sysexits.h>
#include <signal.h>
#include <atomic>

extern std::atomic<int> control_c;

namespace fs = filesystem;
extern fs::path mpw_path();

namespace ToolBox {
	std::string MacToUnix(const std::string path);
	std::string UnixToMac(const std::string path);
}





namespace {

	struct break_command_t {};
	struct continue_command_t {};

	/*
	 * returns:
	 * <0 -> error
	 * 0 -> false
	 * >0 -> true
	 */

	int bad_if(const char *name) {
		fprintf(stderr, "### %s - Missing if keyword.\n", name);
		fprintf(stderr, "# Usage - %s [if expression...]\n", name);
		return -3;
	}
	int evaluate(int type, const std::string &s, Environment &env) {

		auto tokens = tokenize(s, true);
		std::reverse(tokens.begin(), tokens.end());

		int32_t e;

		switch(type) {
			default: return 0;

			case BREAK:
			case CONTINUE:
			case ELSE:
				tokens.pop_back();

				if (tokens.empty()) return 1;

				if (strcasecmp(tokens.back().string.c_str(), "if") != 0) {
					const char *name = "";
					switch(type) {
						case BREAK: name = "Break"; break;
						case CONTINUE: name = "Continue"; break;
						case ELSE: name = "Else"; break;
					}
					return bad_if(name);
				}
				// fall through.
			case IF:
				tokens.pop_back();
				try {
					e = evaluate_expression("If", std::move(tokens));
				}
				catch (std::exception &ex) {
					fprintf(stderr, "%s\n", ex.what());
					return -5;
				}
				break;
		}
		return !!e;
	}
}











fs::path which(const Environment &env, const std::string &name) {
	std::error_code ec;

	if (name.find_first_of("/:") != name.npos) {
		// canonical?
		fs::path p(name);
		if (fs::exists(p, ec)) return name;
		return "";
	}

	std::string s = env.get("commands");
	for (string_splitter ss(s, ','); ss; ++ss) {
		fs::path p(ToolBox::MacToUnix(*ss));
		p /= name;
		if (fs::exists(p, ec)) return p;
	}

	// error..
	return "";
}



void launch_mpw(const Environment &env, const std::vector<std::string> &argv, const fdmask &fds) {


	std::vector<char *> cargv;
	cargv.reserve(argv.size() + 3);


	cargv.push_back((char *)"mpw");
	//cargv.push_back((char *)"--shell");

	unsigned offset = cargv.size();		


	std::transform(argv.begin(), argv.end(), std::back_inserter(cargv),
		[](const std::string &s) { return strdup(s.c_str()); }
	);
	cargv.push_back(nullptr);


	// export environment...

	for (const auto &kv : env) {
		if (kv.second) { // exported
			std::string name = "mpw$" + kv.first;
			setenv(name.c_str(), kv.second.c_str(), 1);
		}
	}

	// handle any indirection...
	fds.dup();


	// re-set all signal handlers.

	/*
	 * execv modifies handlers as such:
	 * blocked -> blocked
	 * ignored -> ignored
	 * caught  -> default action
	 */
	struct sigaction sig_action;

	sig_action.sa_handler = SIG_DFL;
	sig_action.sa_flags = 0;
	sigemptyset(&sig_action.sa_mask);
	for (int i = 1; i < NSIG; ++i) {
		sigaction(i, &sig_action, NULL);
	}

	execv(mpw_path().c_str(), cargv.data());
	perror("execvp: ");
	exit(EX_OSERR); // raise a signal?
}

namespace {

	std::string &lowercase(std::string &s) {
		std::transform(s.begin(), s.end(), s.begin(), [](char c){ return std::tolower(c); });
		return s;
	}

	std::unordered_map<std::string, int (*)(Environment &, const std::vector<std::string> &, const fdmask &)> builtins = {
		{"aboutbox", builtin_aboutbox},
		{"alias", builtin_alias},
		{"directory", builtin_directory},
		{"echo", builtin_echo},
		{"exists", builtin_exists},
		{"export", builtin_export},
		{"parameters", builtin_parameters},
		{"quote", builtin_quote},
		{"set", builtin_set},
		{"shift", builtin_shift},
		{"unalias", builtin_unalias},
		{"unexport", builtin_unexport},
		{"unset", builtin_unset},
		{"version", builtin_version},
		{"which", builtin_which},
	};






	int execute_external(const Environment &env, const std::vector<std::string> &argv, const fdmask &fds) {



		int status;
		int pid;


		pid = fork();
		if (pid < 0) {
			perror("fork: ");
			exit(EX_OSERR);
		}


		if (pid == 0) {
			launch_mpw(env, argv, fds);
		}

		for(;;) {
			int status;
			pid_t ok;
			ok = waitpid(pid, &status, 0);
			if (ok < 0) {
				if (errno == EINTR) continue;
				perror("waitpid:");
				exit(EX_OSERR);
			}

			if (WIFEXITED(status)) return WEXITSTATUS(status);
			if (WIFSIGNALED(status)) return -9; // command-. user abort exits via -9.

			fprintf(stderr, "waitpid - unexpected result\n");
			exit(EX_OSERR);
		}

	}


}



//std::string expand_vars(const std::string &s, const class Environment &);

command::~command()
{}

/*
 * todo -- all errors should be handled the same, regardless of source. (throw, parse, etc).
 * echo and error should respect the active fdmask.
 */

int simple_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	if (control_c) throw execution_of_input_terminated();

	std::string s = expand_vars(text, env);


	process p;
	try {
		auto tokens = tokenize(s, false);
		if (tokens.empty()) return 0;
		parse_tokens(std::move(tokens), p);
	} catch(std::exception &e) {
		fprintf(stderr, "%s\n", e.what());
		return env.status(-4, throwup);
	}

	if (p.arguments.empty()) return 0;
	
	env.echo("%s", s.c_str()); 

	fdmask newfds = p.fds | fds;

	std::string name = p.arguments.front();
	lowercase(name);

	auto iter = builtins.find(name);
	if (iter != builtins.end()) {
		env.set("command", name);
		int status = iter->second(env, p.arguments, newfds);
		return env.status(status, throwup);
	}

	if (env.test()) return env.status(0);
	if (env.startup()) {
		fprintf(stderr, "### MPW Shell - startup file may not contain external commands.\n");
		return env.status(0);
	}

	name = p.arguments.front();
	fs::path path = which(env, name);
	if (path.empty()) {
		fprintf(stderr, "### MPW Shell - Command \"%s\" was not found.\n", name.c_str());
		return env.status(-1, throwup);
	}
	env.set("command", path);
	p.arguments[0] = path;

	int status = execute_external(env, p.arguments, newfds);

	return env.status(status, throwup);
}

int evaluate_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	if (control_c) throw execution_of_input_terminated();

	std::string s = expand_vars(text, env);

	env.set("command", "evaluate");

	env.echo("%s", s.c_str());

	try {
		auto tokens = tokenize(s, true);
		if (tokens.empty()) return 0;

		int status = builtin_evaluate(env, std::move(tokens), fds);

		return env.status(status, throwup);
	} catch (std::exception &e) {
		fprintf(stderr, "%s\n", e.what());
		return env.status(1, throwup);
	}
}


int break_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	if (control_c) throw execution_of_input_terminated();

	std::string s = expand_vars(text, env);

	env.set("command", "break");

	env.echo("%s", s.c_str());
	if (!env.loop()) {
		fputs("MPW Shell - Break must be within for or loop.\n", stderr);
		return env.status(-3, throwup);
	}

	// check/evaluate if clause.
	int status = evaluate(BREAK, s, env);
	if (status > 0)
		throw break_command_t();
	return env.status(status, throwup);

}

int continue_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	if (control_c) throw execution_of_input_terminated();

	std::string s = expand_vars(text, env);

	env.set("command", "continue");

	env.echo("%s", s.c_str());
	if (!env.loop()) {
		fputs("MPW Shell - Continue must be within for or loop.\n", stderr);
		return env.status(-3, throwup);
	}


	// check/evaluate if clause.
	int status = evaluate(CONTINUE, s, env);
	if (status > 0)
		throw continue_command_t();
	return env.status(status, throwup);

}

int or_command::execute(Environment &e, const fdmask &fds, bool throwup) {

	int rv = 0;

	for (auto &c : children) {
		if (!c) continue;
		rv = c->execute(e, fds, false);
		if (rv == 0) return rv;
	}

	return e.status(rv);
}

int and_command::execute(Environment &e, const fdmask &fds, bool throwup) {

	int rv = 0;
	for (auto &c : children) {
		if (!c) continue;
		rv = c->execute(e, fds, false);
		if (rv != 0) return rv;
	}

	return rv;
}


int vector_command::execute(Environment &e, const fdmask &fds, bool throwup) {

	int rv = 0;
	for (auto &c : children) {
		if (!c) continue;
		rv = c->execute(e, fds);
	}
	return e.status(rv);
}

int error_command::execute(Environment &e, const fdmask &fds, bool throwup) {

	if (control_c) throw execution_of_input_terminated();

	std::string s = expand_vars(text, e);

	e.echo("%s", s.c_str());

	switch(type) {
	case END:
		fprintf(stderr, "### MPW Shell - Extra END command.\n");
		break;

	case RPAREN:
		fprintf(stderr, "### MPW Shell - Extra ) command.\n");
		break;

	case ELSE:
	case ELSE_IF:
		fprintf(stderr, "### MPW Shell - ELSE must be within IF ... END.\n");
		break;
	}


	return e.status(-3);
}

namespace {

	int check_ends(const std::string &s, fdmask &fds) {

		// MPW ignores any END tokens other than redirection.
		process p;
		try {
			auto tokens = tokenize(s, false);
			parse_tokens(std::move(tokens), p);
		}
		catch (std::exception &e) {
			fprintf(stderr, "%s\n", e.what());
			return -4;
		}
		fds = p.fds.to_mask();
		return 0;
	}
}

int begin_command::execute(Environment &env, const fdmask &fds, bool throwup) {
	// todo -- parse end for redirection.

	std::string b = expand_vars(begin, env);
	std::string e = expand_vars(end, env);


	env.set("command", type == BEGIN ? "end" : ")");

	// echo!
	env.echo("%s ... %s",
		b.c_str(),
		e.c_str()
	);



	// tokenize the begin and end commands.
	// begin may not have extra arguments.  end may have redirection.

	auto bt = tokenize(b, true);
	if (bt.size() != 1) {
		fprintf(stderr, "### Begin - Too many parameters were specified.\n");
		fprintf(stderr, "Usage - Begin\n");
		return env.status(-3);
	}

	fdmask newfds;
	int status = check_ends(e, newfds);
	newfds |= fds;
	if (status) return env.status(status);

	int rv;
	env.indent_and([&]{
		rv = vector_command::execute(env, newfds);		
	});

	env.echo("%s", type == BEGIN ? "end" : ")");

	return env.status(rv);
}


int loop_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	std::string b = expand_vars(begin, env);
	std::string e = expand_vars(end, env);


	env.set("command", "end");

	// echo!
	env.echo("%s ... %s",
		b.c_str(),
		e.c_str()
	);

	// check for extra tokens...
	auto bt = tokenize(b, true);
	if (bt.size() != 1) {
		fprintf(stderr, "### Loop - Too many parameters were specified.\n");
		fprintf(stderr, "Usage - Loop\n");
		return env.status(-3);
	}

	fdmask newfds;
	int status = check_ends(e, newfds);
	newfds |= fds;
	if (status) return env.status(status);

	int rv = 0;
	for(;;) {

		if (control_c) throw execution_of_input_terminated();

		try {
			env.loop_indent_and([&]{
				rv = vector_command::execute(env, newfds);		
			});
		}
		catch (break_command_t &ex) {
			env.echo("end");
			break;
		}
		catch (continue_command_t &ex) {}
		env.echo("end");
	}
	return env.status(rv);
}

int for_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	std::string b = expand_vars(begin, env);
	std::string e = expand_vars(end, env);


	env.set("command", "end");

	// echo!
	env.echo("%s ... %s",
		b.c_str(),
		e.c_str()
	);

	// check for extra tokens...
	auto bt = tokenize(b, true);
	if (bt.size() < 3 || strcasecmp(bt[2].string.c_str(), "in")) {
		fprintf(stderr, "### For - Missing in keyword.\n");
		fprintf(stderr, "Usage - For name in [word...]\n");
		return env.status(-3);
	}

	fdmask newfds;
	int status = check_ends(e, newfds);
	newfds |= fds;
	if (status) return env.status(status);

	int rv = 0;
	for (int i = 3; i < bt.size(); ++i ) {

		if (control_c) throw execution_of_input_terminated();

		env.set(bt[1].string, bt[i].string);

		try {
			env.loop_indent_and([&]{
				rv = vector_command::execute(env, newfds);		
			});
		}
		catch (break_command_t &ex) {
			env.echo("end");
			break;
		}
		catch (continue_command_t &ex) {}
		env.echo("end");
	}

	return env.status(rv);
}



/*
 * the entire command prints even if there is an error with the expression.
 *
 */
int if_command::execute(Environment &env, const fdmask &fds, bool throwup) {

	int rv = 0;
	bool ok = false;

	std::string e = expand_vars(end, env);

	env.set("command", "end");

	// parse end for indirection.
	fdmask newfds;
	int status = check_ends(e, newfds);
	newfds |= fds;
	if (status) {
		rv = status;
		ok = true;
	}

	for (auto &c : clauses) {
		std::string s = expand_vars(c->clause, env);

		if (c->type == IF)
			env.echo("%s ... %s", s.c_str(), e.c_str());
		else
			env.echo("%s", s.c_str());

		if (ok) continue;

		int tmp = evaluate(c->type, s, env);
		if (tmp < 0) { ok = true; rv = tmp; continue; }
		if (tmp == 0) continue;

		env.indent_and([&](){
			rv = c->execute(env, newfds);
		});
	}

	env.echo("end");
	return env.status(rv);
}