microshell.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   microshell.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: fballest <fballest@student.42.fr>          +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2022/03/31 11:16:22 by fballest          #+#    #+#             */
/*   Updated: 2022/03/31 11:20:28 by fballest         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>

int     ft_strlen(char *str)
{
    int i = 0;
    while(str[i])
        i++;
    return(i);
}

void    ft_error(void)
{
    write(2, "error: fatal\n", ft_strlen("error: fatal\n"));
    exit (1);
}

void    ft_msg(char *str, char *com)
{
    write(2, str, ft_strlen(str));
    write(2, com, ft_strlen(com));
    write(2, "\n", 1);
}

void    ft_cd(char **argv)
{
    int i = 0;
    while (argv[i])
        i++;
    if (i != 2)
        write (2, "error: cd: bad arguments\n", ft_strlen("error: cd: bad arguments\n"));
    if (chdir(argv[1]))
        ft_msg("error: cd: cannot change directory to ", argv[1]);
    
}

int main(int argc, char **argv, char **env)
{
    int     j = 1, j_prev, pipes[2], status, type;
    char    **command;
    pid_t   pid;
    while (j < argc)
    {
        j_prev = j;
        type = 0;
        while (j < argc && strcmp(argv[j], "|") && strcmp(argv[j], ";"))
            j++;
        if (j < argc && !strcmp(argv[j], "|"))
            type = 2;
        if (j < argc && !strcmp(argv[j], ";"))
            type = 1;
        argv[j] = 0;
        command = &argv[j_prev];
        if (type == 2 && pipe(pipes))
            ft_error();
        pid = fork();
        if (pid < 0)
            ft_error();
        if (pid == 0)
        {
            if (type == 2)
                dup2(pipes[1], 1);
            if (!strcmp(command[0], "cd"))
                ft_cd(command);
            else if (execve(command[0], command, env))
                ft_msg("error: cannot execute ", command[0]);
            exit (0);
        }
        else
            waitpid(pid, &status, 0);
        if (type == 2)
        {
            dup2(pipes[0], 0);
            close(pipes[1]);
            close(pipes[0]); 
        }
        if (type == 0)
            break;
        j++;
    }
    return (0);
}