initial code commit

.gitignore

@@ -0,0 +1 @@
+*.out

Makefile

@@ -0,0 +1,9 @@
+LIBRARIES = -lreadline
+RELEASE_ARGS = -DRELEASEBUILD
+SOURCES = ./msh.c
+
+build:
+	gcc -Wall -std=gnu99 ${RELEASE_ARGS} ${SOURCES} ${LIBRARIES}
+
+debug:
+	gcc -Wall -std=gnu99 ${SOURCES} ${LIBRARIES}

msh.c

@@ -0,0 +1,242 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <string.h>
+
+#include <readline/readline.h>
+#include <readline/history.h>
+
+#include "msh.h"
+
+#define clear() printf("\033[H\033[J")
+
+union pipe {
+	int fileDesc[2];
+	struct {
+		int read;
+		int write;
+	};
+};
+
+static char *builtinFunctions[] = {
+	"exit",
+	"author"
+};
+
+int (*builtinFunc[]) (char *) = {
+	&builtinExit,
+	&builtinAuthor
+};
+
+int builtinExit() {
+	exit(EXIT_SUCCESS);
+}
+
+int builtinAuthor() {
+	static const char* message =
+		"Author: Spencer\n"
+		"Description: A shell to promote math!\n"
+		"Ask for the source code!\n"
+		"\n";
+	printf("%s", message);
+	return 0;
+}
+
+void failedTest() {
+	static const char* message =
+		"\n"
+		"How can you expect to execute commands without knowing any math???\n"
+		"\n";
+	printf("%s", message);
+	return;
+}
+
+int runCommand(char *command) {
+	int status = 0;
+	union pipe input, output;
+	FILE *inputFileD, *outputFileD;
+	char *line = NULL;
+	size_t lineCap = 0;
+	pid_t pid;
+
+	pipe(input.fileDesc);
+	pipe(output.fileDesc);
+
+	pid = fork();
+	if (pid == 0) { // Child process
+		close(input.write);
+		close(output.read);
+
+		dup2(input.read, STDIN_FILENO);
+		dup2(output.write, STDOUT_FILENO);
+
+		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
+		close(input.read);
+		close(output.write);
+		inputFileD = fdopen(input.write, "w");
+		outputFileD = fdopen(output.read, "r");
+
+		while (getline(&line, &lineCap, outputFileD) > 0) {
+			printf("%s", line);
+		}
+
+		free(line);
+
+		do {
+			waitpid(pid, &status, WUNTRACED);
+		} while(!WIFEXITED(status) && !WIFSIGNALED(status));
+		fclose(inputFileD);
+		fclose(outputFileD);
+	}
+
+	return status;
+}
+
+int execCommand(char *command) {
+	for (int i = 0; i < (sizeof(builtinFunctions) / sizeof(char *)); i++) {
+		if (strcmp(command, builtinFunctions[i]) == 0) {
+			return (*builtinFunc[i])(command);
+		}
+	}
+	return runCommand(command);
+}
+
+void initShell() {
+	FILE *fd;
+
+	clear();
+	using_history();
+
+	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);
+	} else {
+		printf("MOTD is empty\n");
+	}
+
+	return;
+}
+
+char *getPrompt() {
+	pid_t pid;
+	union pipe input, output;
+	FILE *outputFileD;
+	size_t len = 0;
+
+	static char *prompt = NULL;
+	static size_t promptCap = 0;
+
+	pipe(input.fileDesc);
+	pipe(output.fileDesc);
+
+	pid = fork();
+	if (pid == 0) { // Child process
+		close(input.write);
+		close(output.read);
+
+		dup2(input.read, STDIN_FILENO);
+		dup2(output.write, STDOUT_FILENO);
+		close(STDERR_FILENO); // Do not print errors to the screen
+
+		execlp("bash", "bash", "-i", "-c", "echo \"${PS1@P}\"", NULL);
+	} else if (pid < 0) { // Error forking
+		printf("Error forking\n");
+	} else { // Parent process
+		close(input.read);
+		close(output.write);
+
+		outputFileD = fdopen(output.read, "r");
+
+		len = getline(&prompt, &promptCap, outputFileD);
+
+		if (prompt[len - 1] == '\n') {
+			prompt[len - 1] = '\0';
+		}
+
+		fclose(outputFileD);
+	}
+
+	return prompt;
+}
+
+int randomNum(int limit) {
+	int num = 0;
+	if (limit != 0) {
+		num = rand()%limit +1;
+	} else {
+		num = rand();
+	}
+	return num;
+}
+
+int mathTest() {
+	int status = 0;
+	int numAnswer = 0;
+	int num1 = randomNum(10);
+	int num2 = randomNum(10);
+	printf("%d + %d = ", num1, num2);
+	scanf("%d", &numAnswer);
+
+	#ifdef RELEASEBUILD
+	printf("Calculating");
+	for (int i = 0; i < 15; i++){
+		printf(".");
+		fflush(stdout);
+		sleep(2);
+	}
+	printf("\n");
+	#endif
+
+	if ((num1 + num2) != numAnswer) { // If wrong answer
+		status = 1;
+	}
+	return status;
+}
+
+
+void startShell() {
+	char *line = NULL;
+	int status = 0;
+
+	while ((line = readline(getPrompt())) != NULL) {
+		if (strlen(line) != 0) { // Checking if prompt returns empty
+			status = mathTest();
+			if (status == 0) { // Passed math test
+				add_history(line);
+				execCommand(line);
+			} else { // Failed math test
+				failedTest();
+			}
+		}
+		free(line);
+	}
+}
+
+void handleBreak(int sig){
+	printf("\n");
+	printf(getPrompt());
+}
+
+int main() {
+	initShell();
+	signal(SIGINT, handleBreak);
+	startShell();
+	exit(EXIT_SUCCESS);
+}

msh.h

@@ -0,0 +1,2 @@
+int builtinExit();
+int builtinAuthor();