orsh/src/main.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <pwd.h>
#include <libgen.h>
#include <signal.h>
#include <readline/readline.h>
#include <readline/history.h>

int position = 0;
char pwd[128]; // FIXME: change to PATH_MAX
char hostname[1024]; // Hostname of machine
struct passwd *pw; // Struct of passwd for uid
char *username; // Current username
char *homedir; // HOME directory of current user
pid_t shell_pid; // pid of current shell (gets only on start)
pid_t pid; // FIXME: this shouldn't be global i think
char prompt[2048]; 

char **split_line(char *line, char *delim) {
	int bufsize = 64;
	position = 0;
	char **tokens = malloc(bufsize * sizeof(char*));
	char *token;

	if (!tokens) {
		fprintf(stderr, "orsh: allocation error\n");
		exit(EXIT_FAILURE);
	}

	token = strtok(line, delim);
	while (token != NULL) {
		tokens[position] = token;
		position++;
		token = strtok(NULL, delim);
	}
	tokens[position] = NULL;
	return tokens;
}

int execute(char **command, int status) {
	status = 0;
	pid_t wpid;

	pid = fork();
	if (pid == 0) {
		// Child process
		if (execvp(command[0], command) == -1) {
			perror("orsh");
		}
		status = 1; // FIXME: add error status
		exit(EXIT_FAILURE);
	} else if (pid < 0) {
		// Error forking
		perror("orsh");
		status = 1; // FIXME: add error status
	} else {
		// Parent process
		do {
			wpid = waitpid(pid, &status, WUNTRACED); // FIXME: warning unused variable
		} while (!WIFEXITED(status) && !WIFSIGNALED(status));
	}

	if (status >= 256)
		status = 1;
	return status;
}

int parse_command(char **command, int status) {
	int variable = 0;
	int where_var[position - 1];
	for (int i = 0; i <= position - 1; i++) { // Loop for checking if line has variable
		if (command[i][0] == '$') { // FIXME
			where_var[i] = 1;
			variable++;
		} else if (command[i][0] == '~') { // FIXME
			command[i] = homedir;
		}
	}
	if (variable >= 1) {
		for (int i = 0; i <= position - 1; i++) {
			if(where_var[i] == 1) {
				command[i]++; // Deleting '$' char
				if(!strcmp(command[i], "?")) {
					char status_string[256]; // FIXME
					sprintf(status_string, "%d", status);
					command[i] = status_string;
				} else {
					command[i] = getenv(command[i]);
					if (command[i] == NULL)
						command[i] = "";
				}
			}
		}
	}

	if (command[0][strlen(command[0]) - 1] == ';'){ // FIXME: parse all word not only first
		command[0][strlen(command[0])-1] = '\0';
	} else if (command[0][0] == ';'){ // Check if command is ; or first char of command is ;
		command[0][0] = '\0';
	}

	if (status >= 256)
		status = 1;

	if (!strcmp(command[0], "exit")) { // FIXME: add switch statement (if possible)
		printf("exit\n");
		exit(0);
	} else if (!strcmp(command[0], "echo")) {
		for (int i = 1; i <= position - 1; i++)
			printf("%s ", command[i]);
		printf("\n");
		return 0;
	} else if (!strcmp(command[0], "cd")) {
		if (position == 1) {
			chdir(homedir);
			getcwd(pwd, sizeof(pwd));
		} else if (position >= 3) {
			printf("orsh: cd: too many arguments\n");
		} else {
			chdir(command[1]);
			getcwd(pwd, sizeof(pwd));
		}
	} else if (!strcmp(command[0], "pwd")) {
		printf("%s\n", pwd);
	} else if (!strcmp(command[0], "export")) {
		for (int i = 1; i <= position - 1; i++) {
			status = putenv(command[i]);
			if (status != 0)
				return status;
		}
	} else if (!strcmp(command[0], "!")) {
		if (status != 0)
			status = 0;
		else if (status == 0)
			status = 1;
	} else {
		status = execute(command, status);
	}
	return status;
}



void init() { // Some initial tasks
	getcwd(pwd, sizeof(pwd)); // Get directory where shell was started
	gethostname(hostname, sizeof(hostname)); // Get hostname
	pw = getpwuid(getuid()); // Get passwd struct for current uid
	username = pw->pw_name;
	homedir = pw->pw_dir;
	shell_pid = getpid();
}

void gen_prompt() {
	// TODO: add parsing config file
	if (!strcmp(pwd, homedir)) {
		sprintf(prompt, "%s@%s %s> ", username, hostname, "~");
	} else {
		sprintf(prompt, "%s@%s %s> ", username, hostname, basename(pwd));
	}
}

void signal_handler(int sig) {
	if (pid == 0 || shell_pid == getpid()) {
		printf("\n");
		printf("%s", prompt);
	} else
		raise(sig);

}

int main(int argc, char *argv[]) {
	char *line = NULL;
	char script_line[100]; // FIXME
	init();
	char** commands;
	char** args;
	int status = 0; // FIXME
	int command_status = 0; // FIXME
	signal(SIGINT, signal_handler);
	if (argc >= 2) {
		FILE *script = fopen(argv[1], "r");
		if (script == NULL) {
			printf("Error opening file: %s\n", argv[1]); // FIXME: add proper error message
			return 1;
		}
		while (fgets(script_line, 100, script) != NULL) {
			args = split_line(script_line, " ");
			command_status = parse_command(args, command_status);
		}

	} else {
		using_history();
		while(1) {
			gen_prompt();
			line = readline(prompt); // FIXME: add prompt
			if (line == NULL) {
				printf("exit\n");
				break;
			}
			add_history(line);
			commands = split_line(line, ";");
			int after_parse_position = position; // To know where we in ; list FIXME
			for (int i = 0; i <= after_parse_position - 1; i++) {
				args = split_line(commands[i], " ");

				command_status = parse_command(args, command_status);
			}
		}

	}
	return command_status;
}