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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   microshell.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: lduplain <[email protected]>      +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2021/01/09 15:59:05 by gbaud             #+#    #+#             */
/*   Updated: 2022/03/01 14:54:35 by lduplain         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

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

#define ERR_FATAL "error: fatal\n"
#define ERR_EXEC "error: cannot execute "
#define ERR_CD_ARG "error: cd: bad arguments\n"
#define ERR_CD_DIR "error: cd: cannot change directory to "

int ft_strlen(char *str)
{
    int index;

    index = 0;
    while (str[index])
        index++;
    return (index);
}

int put_err(char *err, char *path)
{
    write(2, err, ft_strlen(err));
    if (path != NULL)
    {
        write(2, path, ft_strlen(path));
        write(2, "\n", 1);
    }
    return (1);
}

void    sub(char **cmds, char **av, int from, int to)
{
    int cmd_arg_index;

    cmd_arg_index = 0;
    while (from < to)
        cmds[cmd_arg_index++] = av[from++];
    cmds[cmd_arg_index] = NULL;
}

int cd(char **av, int len)
{
    if (len != 2)
        return (put_err(ERR_CD_ARG, NULL));
    if (chdir(av[1]))
        return (put_err(ERR_CD_DIR, av[1]));
    return (0);
}

int main(int argc, char **argv, char **env)
{
    int     arg_index;
    int     next_semi;
    int     cmd_index;
    int     next_pipe;
    int     pipefd[2];
    pid_t   pid;
    int     fd_in;

    arg_index = 1;
    while (arg_index < argc)
    {
        next_semi = arg_index;
        while (next_semi < argc && strncmp(argv[next_semi], ";", 2) != 0)
            next_semi++;

        fd_in = 0;

        cmd_index = arg_index;
        while (cmd_index < next_semi)
        {
            next_pipe = cmd_index;
            while (next_pipe < next_semi && strncmp(argv[next_pipe], "|", 2) != 0)
                next_pipe++;

            char *cmds[next_pipe - cmd_index + 1];
            sub(cmds, argv, cmd_index, next_pipe);

            pipe(pipefd);
            if ((pid = fork()) == -1)
                return (put_err(ERR_FATAL, NULL));
            else if (pid == 0)
            {
                dup2(fd_in, 0);
                if (next_pipe < next_semi)
                    dup2(pipefd[1], 1);
                close(pipefd[0]);
                if (strncmp(cmds[0], "cd", 3) == 0)
                    cd(cmds, next_pipe - cmd_index);
                else if (execve(cmds[0], cmds, env) == -1)
                {
                    close(pipefd[1]);
                    close(fd_in);
                    return (put_err(ERR_EXEC, cmds[0]));
                }
                close(pipefd[1]);
                close(fd_in);
                return (0);
            }
            else
            {
                waitpid(pid, NULL, 0);
                close(pipefd[1]);
                if (fd_in)
                    close(fd_in);
                fd_in = pipefd[0];
            }
            cmd_index = next_pipe + 1;
        }
        close(fd_in);
        arg_index = next_semi + 1;
    }
    return (0);
}