First and Final commit

Author: gonidelis

myShell.c

@@ -0,0 +1,344 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <errno.h>
+
+
+void takeIn(char in[]){
+
+	fgets(in,512,stdin);
+	
+	//exclude '\n' character (enter) from string-input
+	int i = 0;
+	while (in[i]!='\0'){
+		i++;
+	}
+	in[i-1]='\0';
+}
+
+
+void parse(char input[], char* toks[],const char delimeter[]){
+	//general parsing function
+	char *token;
+	int i=0;
+	token = strtok(input, delimeter);
+
+	while( token != NULL ) {
+
+		toks[i]=token;
+     	i ++;
+      	token = strtok(NULL, delimeter);
+
+  	}
+  	toks[i] = NULL;
+
+}
+
+
+int seperateCommands(char input[],char *cmds[], bool* success){
+	char *token; 	
+	int i=0,pos=0;
+	
+	//find all delimiters
+	for(int j=0;j<strlen(input)-1;j++){
+		if(input[j]=='&' && input[j+1]=='&'){
+			success[pos]=true;
+			pos++;
+		}else if(input[j]==';'){
+			success[pos]=false;
+			pos++;
+		}
+	}
+
+	//split the commands
+
+	parse(input, cmds, ";&&"); //parse iput in ';' or '&&'
+
+  	return pos+1; 	//pos+1 = number of commands
+}
+
+
+int executeCmd(char* tokens[]){
+	int status;
+	pid_t child_pid;
+
+	child_pid = fork();
+
+  	if(child_pid == 0) {
+    	/*child process. */
+    	if (execvp(tokens[0], tokens)<0){
+    		perror(tokens[0]); 
+    		return -1;
+    	}
+ 	}else if(child_pid<0){
+ 		perror("Fork failed");
+ 		return 1;
+	} else {
+        waitpid(child_pid, &status, WUNTRACED);
+    }
+	if (status==0){
+		return 0;
+	}else{
+		return -1;
+	}
+}		
+
+int findPipe(char cmds[]){
+	if(strchr(cmds, '|')!=NULL){
+		return 1;
+	}else{
+		return 0;
+	}
+}
+
+int findRedirection(char cmds[]){
+
+	if(strchr(cmds, '>')!=NULL){
+		return 1;
+	}else if(strchr(cmds, '<')!=NULL){
+		return 2;
+	}else{
+		return 0;
+	}
+}
+
+int executeRedirection(char cmds[], int f){
+
+	char *tokens1[512];
+	char *tokens2[512];
+	int status;
+	pid_t child_pid;
+
+	parse(cmds, tokens1, "<>"); //parse in spaces or '<' or '>'
+
+	parse(tokens1[0], tokens2, " \t");
+
+	char *token= strtok(tokens1[1], " \t");
+	
+	while( tokens1[1] == " \t") {
+
+      	token = strtok(NULL, " \t");
+
+  	}
+
+	char *fileName= token;
+
+	FILE* file = fopen(fileName, "a+");
+	 
+	child_pid = fork();
+
+  	if(child_pid == 0) {
+    	/* This is done by the child process. */
+    	if(f==1){
+    		close(1); //close stdout
+			dup2(fileno(file),fileno(stdout)); //stout goes to file        	
+
+		}else if(f==2){
+			close(0); //close stdin
+			dup2(fileno(file),fileno(stdin)); //stdin is in file
+		}
+
+    	if (execvp(tokens2[0], tokens2)<0){
+    		perror(tokens2[0]); 
+    		exit(1);
+    	}
+ 	}else if(child_pid<0){
+ 		perror("Fork failed");
+ 		dup2(fileno(file),fileno(stderr)); //stderr goes to file
+ 		exit(1);
+	} else {
+		fclose(file);
+        waitpid(child_pid, &status, WUNTRACED);
+    }
+
+	if (status==0){
+		return 0;
+	}else{
+		return -1;
+	}
+
+}
+
+
+
+int executePipe(char cmds[]){
+	int stat1, stat2;	//process1 status1,process2 status2
+	pid_t pid1, pid2;
+	int fd[2];
+	char *tokens1[512];
+	char *tokens2[512];
+	char *tokens3[512];
+
+	parse(cmds, tokens1, "|"); //tokens1 contains the cmds 
+
+	// Create a pipe.
+	if(pipe(fd) == -1){
+		perror("Pipe failed");
+        return -1;
+	}
+
+	int r1,r2;
+	r1=findRedirection(tokens1[0]);
+	r2=findRedirection(tokens1[1]);
+
+	// Create our first process.
+	pid1 = fork();
+	if (pid1 < 0) {
+      perror("Fork failed");
+      exit(1);
+    }else if (pid1 == 0) { 
+        dup2(fd[1], 1);
+        close(fd[0]);
+        if(r1==0){
+        	parse(tokens1[0], tokens2, " \t"); //tokens2 the 1st cmd(pefore pipe)
+        	execvp(tokens2[0], tokens2); // run command BEFORE pipe character in userinput
+        	perror("Execvp failed");
+        	exit(1);
+        }else{
+        	executeRedirection(tokens1[0],r1);
+        	exit(0);
+        }
+        
+    } 
+    close(fd[1]);
+	// Wait for everything to finish and exit.
+	waitpid(pid1, &stat1, WUNTRACED);
+
+	// Create our second process.
+    pid2 = fork();
+    if (pid2 < 0) {
+      perror("Fork failed");
+      exit(1);
+    }else if (pid2 == 0) { 
+        dup2(fd[0], 0);
+        close(fd[1]);
+        if(r2==0){
+        	parse(tokens1[1], tokens3, " \t"); //tokens3 the 2nd cmd(after pipe)
+        	execvp(tokens3[0], tokens3); // run command AFTER pipe character in userinput
+        	perror("Execvp failed");
+        	exit(1);
+        }else{
+        	executeRedirection(tokens1[1],r2);
+        	exit(0);
+        }
+    }
+    close(fd[0]);
+    waitpid(pid2, &stat2, WUNTRACED);
+
+
+    if (stat1==0 && stat2==0){
+    	return 0;
+    }else{
+    	return -1;
+    }
+    
+
+}
+
+void parseExec(char *input){
+
+	int redirectionFound=-10;	//random non valid initialization
+	int pipeFound=-10;
+	int numOfCmds=0;
+	char *cmds[512]; 	//commands stored seperately
+	char *toks[512]; 	//parts of each command stored seperately
+	bool *success=(bool *)malloc(512*sizeof(bool));
+	//**********parse multiple commands**************
+	numOfCmds = seperateCommands(input, cmds, success);
+	//***********parse/execute each command**************************
+	for (int i =0 ; i<numOfCmds; i++){
+		//check for exit
+		if(strcmp(cmds[i],"quit") == 0){
+			exit(0);
+		}
+
+		pipeFound=findPipe(cmds[i]);
+		redirectionFound=findRedirection(cmds[i]);
+		
+		if(pipeFound==0 && redirectionFound==0){
+			//Neither pipe nor redirection found
+			parse(cmds[i], toks, " \t"); //parse space
+			if (executeCmd(toks)==-1 && success[i]==1){
+				break;
+			}
+		
+		}else if(pipeFound==0 && (redirectionFound==1 || redirectionFound==2)){
+			//Redirection only
+			if (executeRedirection(cmds[i],redirectionFound)==-1 && success[i]==1){
+				break;
+			}
+		}else{
+			//pipe only
+			if (executePipe(cmds[i])==-1 && success[i]==1){
+				break;
+			}
+		}
+	}
+
+}
+
+
+void shell(){
+	//user_aem
+	printf("gonidelis_8794>");
+
+	//*************initiallization*****************
+	char in[512]; 	//string-input from user
+	
+	//***********take input from user****************
+	takeIn(in);
+	parseExec(in);
+	shell();
+}
+
+int batchfile_mode(char * argv[]){
+
+	char str[512];
+	char *batch_cmds[512];
+	int i=0, j=0; 
+	int n;	//number of batchfile commands
+
+	FILE *fp;
+	fp = fopen(argv[1], "r");
+
+	if(fp == NULL) {
+  		perror("Error opening file");
+  		return(-1);
+	 	}
+	 	
+	while(fgets(str,512, fp)!=NULL){
+		batch_cmds[i] = strdup(str);
+		i++;
+		n = i;
+	}
+
+	for (i=0;i<n;i++){
+
+		
+		batch_cmds[i] = strtok(batch_cmds[i], "\n");
+
+		parseExec(batch_cmds[i]);
+	}
+	
+
+	fclose(fp);
+
+	return 0;
+}
+
+
+int main(int argc, char *argv[]){
+	if (argc >=2){
+		//batchfile mode
+		batchfile_mode(argv);
+
+	}else{
+		//interactive mode
+		shell();	//shell() called recursively	
+	}
+	
+	return 0;
+}