default_shell/cmd/dfs.c

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>

#include <readline/readline.h>
#include <readline/history.h>

#include "dfs.h"
#include "util.h"

#define clear() printf("\033[H\033[J")

char *prompt = NULL;
static size_t commandRun = 0;

static char *builtinFunctions[] = {
	"exit",
	"author",
	"cd",
	"nomorenumbers"
};

int (*builtinFunc[]) (char **) = {
	&builtinExit,
	&builtinAuthor,
	&builtinCD,
	&builtinNMN
};

int builtinExit(char **args) {
#if RL_READLINE_VERSION < 0x0602
	rl_clear_history();
#else
	clear_history();
#endif
	exit(EXIT_SUCCESS);
}

int builtinAuthor(char **args) {
	static const char* message =
		"Author: Spencer\n"
		"Description: \n"
		"Ask for the source code!\n"
		"\n";
	printf("%s", message);
	return 0;
}

int builtinCD(char **dir) {
	int status = 0;
	char *oldPWD = getenv("PWD");
	char *changeDir = malloc(sizeof(char *));
	if (dir[1] != NULL) {
		char c = *dir[1];
		switch (c) {
			case '~':
				changeDir = realloc(changeDir, strlen(getenv("HOME") + strlen(dir[1])));
				strcpy(changeDir, getenv("HOME"));
				strcat(changeDir, dir[1]+1);
				break;
			case '-':
				changeDir = realloc(changeDir, strlen(getenv("OLDPWD")));
				strcpy(changeDir, getenv("OLDPWD"));
				break;
			default:
				changeDir = dir[1];
				break;
		}
		if (chdir(changeDir) != 0) {
			status = 1;
			printf("bash: cd: error\n");
		} else {
			setenv("PWD", dir[1], 1);
			setenv("OLDPWD", oldPWD, 1);
			free(prompt);
			prompt = NULL;
		}
	} else {
		if (chdir(getenv("HOME")) != 0) {
			status = 1;
			printf("Bash: cd: error\n");
		} else {
			setenv("PWD", getenv("HOME"), 1);
			setenv("OLDPWD", oldPWD, 1);
			free(prompt);
			prompt = NULL;
		}
	}
	free(changeDir);
	changeDir = NULL;
	return status;
}

int builtinNMN(char **args) {
	return 0;
}

void failedTest() {
	static const char* message =
		"\n"
		"We must change our default passwords; however, it seems you have typed it in wrong!!\n"
		"\n";
	printf("%s", message);
	return;
}

int runCommand(char *command) {
	int status = 0;
	pid_t pid;

	pid = fork();
	if (pid == 0) { // Child process
		if(execlp("bash", "bash", "-c", command, NULL) == -1) {
			exit(EXIT_FAILURE);
		}
		exit(EXIT_SUCCESS);
	} else if (pid < 0) {
		printf("Error forking...\n");
		status = 1;
	} else { // Parent process
		do {
			waitpid(pid, &status, WUNTRACED);
		} while(!WIFEXITED(status) && !WIFSIGNALED(status));
	}

	return status;
}

char **splitCMD(const char *line, size_t *length) {
        size_t size = 8;
        size_t pos = 0;
        char **args = malloc(size * sizeof(char*));
        char *arg = NULL;

        if(line == NULL) {
                *args=NULL;
                return args;
        }

	char *lineTest = strdup(line);

        arg = strtok(lineTest, " \t\r\n\a");
        while (arg != NULL) {
                if (pos >= size) {
                        size *= 2;
                        args = realloc(args, size * sizeof(char*));
                }

		*length += 1;
                args[pos] = strdup(arg);
                pos++;

                arg = strtok(NULL, " \t\r\n\a");
        }

	free(lineTest);
        return args;
}

int execCommand(char *command) {
	size_t commandLen = 0;
	char **commandARGS = splitCMD(command, &commandLen);
	for (size_t i = 0; i < (sizeof(builtinFunctions) / sizeof(char *)); i++) {
		if (strcmp(commandARGS[0], builtinFunctions[i]) == 0) {
			(*builtinFunc[i])(commandARGS);
			for (size_t i = 0; i < commandLen; i++) {
				free(commandARGS[i]);
			}
			free(commandARGS);
			return 0;
		}
	}

	for (size_t i = 0; i < commandLen; i++) {
		free(commandARGS[i]);
	}

	free(commandARGS);
	return runCommand(command);
}

void initShell() {
	FILE *fd;

	clear();
	using_history();

	// Setting random time seed
	srand(time(0));

	fflush(stdout);
	runCommand("uname -a");

	fd = fopen("/etc/motd", "r");
	if (fd != NULL) {
		char c;
		c = fgetc(fd);
		printf("\n");
		while (c != EOF) {
			printf("%c", c);
			c = fgetc(fd);
		}
		fclose(fd);
	}

	printf("\n");

	return;
}

int randomNum(int limit) {
	int num = 0;
	if (limit != 0) {
		num = rand()%limit + 1;
	} else {
		num = rand();
	}
	return num;
}

int shellTest() {
	int status = 1;
	char *line = NULL;

	line = readline("Default password? (abc123): ");

	if (line != NULL) {
		if(!strcmp(line, "abc123")) {
			status = 0;
		}
	}

	free(line);
	return status;
}

void postCommand() {
	commandRun++;
	return;
}

void startShell() {
	char *line = NULL;
	int status = 0;

	while ((line = readline(getPrompt())) != NULL) {
		if (strlen(line) != 0) { // Checking if prompt returns empty
			status = shellTest();
			if (status == 0) { // Passed test
				add_history(line);
				execCommand(line);
				postCommand();
			} else { // Failed test
				failedTest();
			}
		}
		free(line);
	}
	free(prompt);
	prompt = NULL;
}

void handleBreak(){
	signal(SIGINT, handleBreak);
	printf("\n");
	rl_on_new_line();
	rl_replace_line("", 0);
	rl_redisplay();
}

int main() {
	initShell();
	signal(SIGINT, handleBreak);
	startShell();
#if RL_READLINE_VERSION < 0x0602
	rl_clear_history();
#else
	clear_history();
#endif
	exit(EXIT_SUCCESS);
}