icsh.c

/* ICCS227: Project 1: icsh
 * Name: Yossatorn Phithakjiraroj
 * StudentID: 6280942
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <unistd.h>
#include <sys/wait.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>

#define MAX_CMD_BUFFER 255

int i, status, pid;
char *res, last_command[MAX_CMD_BUFFER], *argv[3];
void my_history(char *), my_read(char *);
int command(char *);

struct test
{
  pid_t pid;
  int stage; // 0-> Non, 1=running, 2=stop, 3=done
  char str[100];
};

struct test tli[100]; // -> tli [1] [2] ....
                      // -> tli [test1] ....

int addStruct(struct test *tli, pid_t pid, char *str, int stage);

void handler(int signum) {
    if (signum == SIGINT && pid == 0) {
      kill(pid, SIGINT);
    } else if (signum == SIGTSTP && pid == 0) {
      signal(SIGTSTP, SIG_DFL);
    }
}

int main(int argc, char * argv []) {
	
	char buffer[MAX_CMD_BUFFER];
	struct sigaction new_action;
  sigemptyset(&new_action.sa_mask);
  new_action.sa_handler = handler;
  new_action.sa_flags = 0;
  sigaction(SIGINT, &new_action, NULL);
  sigaction(SIGTSTP, &new_action, NULL);
  if (argc > 1) {
		my_read(argv[1]);
	}
	while(1) {
		printf("icsh $ ");
    fgets(buffer, 255, stdin);
    command(buffer);
	}
}

int command(char *buffer) {
    if (strstr(buffer, "echo")){
		my_history(buffer);
        for (res = buffer ; *res && *res != ' ' ; res++)
            ;
        if (*res) res++;
        printf("%s", res);
    } 
    else if (strstr(buffer, "!!")){
		strcpy(buffer, last_command);
		// printf("%s", buffer);
		command(buffer);
    } 
    else if (strstr(buffer, "exit")) {
        for (res = buffer ; *res && *res != ' ' ; res++)
            ;
        if (*res) res++;
        if (atoi(res) && atoi(res) >= 1) {
            // printf("bye\n");
            exit(atoi(res));
        } 
		// else { printf("bad command\n"); }
    } else if (strstr(buffer, ">")) {
      char * token = strtok(buffer, ">");
      char *p = strrchr(buffer, ' ');
      int file_desc = open(p+2, O_TRUNC | O_CREAT | O_WRONLY, 0666);
      if ((pid=fork())==0){
        dup2(file_desc, 1);
        system(token);
        close(file_desc);
      }
      close(file_desc);
    } else if (strstr(buffer, "help")) {
      printf("This shell's built-in function contains\n");
      printf("--> echo <text> -- the echo command prints a given text (until EOL) back to the console.\n");
      printf("--> echo $?  -- this prints out the exit status code of the previous command. You may assume that all build-in commands exits with exit code 0\n");
      printf("--> In the case of >, the output of the program will be redirected to the specified file name.\n");
      printf("--> jobs - list current jobs \n");
      printf("--> fg %c<job_id>: Brings the job identified by <job_id> into the foreground.\n", '%');
      printf("--> etc.\n")
    } else if (strstr(buffer, "jobs")) {
        for (int i = 1; i < 100; i++) {
          if (tli[i].pid != 0) {
            if (tli[i].stage == 1) { 
              char Stage[] = "Running";
              printf("[%d] %s %s", i, Stage, tli[i].str);
            } else if (tli[i].stage == 2) { 
              char Stage[] = "Stopped";
              printf("[%d] %s %s", i, Stage, tli[i].str);
            }
          }
        }
      } else if (strstr(buffer, "fg")){
        for (res = buffer ; *res && *res != '%' ; res++)
            ;
        char *b = res + 1;
        int i = atoi(b);
        kill(-(tli[i].pid), SIGCONT);
        waitpid(tli[i].pid, NULL, WUNTRACED);
        tli[i].stage = 3;
        return 1;
      } else if (strstr(buffer, "&")) {
      pid = fork();
        if (pid == 0) { // <-- Child
          char * token = strtok(buffer, "&");
          system(token);
          printf("\n Done %s", token);
          exit(0);
        } else {
          int job_id = addStruct(tli, pid, buffer, 1);
          printf("[%d] %d \n", job_id, pid);
          return 1;
        }
    } else {
        pid = fork();
        if (pid < 0) {
          perror("Fork Error");
        } else if (pid == 0) {
			    system(buffer);
          exit(0);
        }
        waitpid(pid, NULL, 0); 
	}
  return 1;
}

void my_history(char *buffer){
	strcpy(last_command, buffer);
}

void my_read(char *filename) {
	FILE* ptr;
    ptr = fopen(filename, "r");
	char line[500];
	while (fgets(line, sizeof(line), ptr)) {
		command(line);
	}
    fclose(ptr);
}

int addStruct(struct test *tli, pid_t pid, char *str, int stage){
  for (int i = 1; i < 100; i++){
    if (tli[i].pid == 0) {
      tli[i].pid = pid;
      tli[i].stage = stage;
      strcpy(tli[i].str, str);
      return i;
    }
  }
  return -1;
}