fakebash.py

#!/usr/bin/env python3

import time

class FakeFileType:
    def __init__(self, permission, user, group, size, create_time):
        self.PERMISSION = permission
        self.USER = user
        self.GROUP = group
        self.SIZE = size
        self.CREATE_TIME = create_time

class FakeDirType:
    def __init__(self, permission, user, group, create_time, files = {}):
        self.PERMISSION = 'd' + permission
        self.USER = user
        self.GROUP = group
        self.SIZE = 4096
        self.CREATE_TIME = create_time
        self.FILES = files

class FakeBash:
    WELCOME_MESSAGE = 'Linux vultr.guest 4.9.0-6-amd64 #1 SMP Debian 4.9.88-1 (2018-04-29) x86_64\n\
\n\
The programs included with the Debian GNU/Linux system are free software;\n\
the exact distribution terms for each program are described in the\n\
individual files in /usr/share/doc/*/copyright.\n\
\n\
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent\n\
permitted by applicable law.'
    HOME_DIR = '/root'
    BASH_PREFIX = 'root@vultr:{}# '
    __WORK_DIR = '/root'

    FILES_LIST = {
        'bin': FakeDirType('rwxr-xr-x', 'root', 'root', 'Mar\t12\t02:31', {
            'bash': FakeFileType('-rwxr-xr-x', 'root', 'root', 1099016, 'Mar\t14\t2016'),
            'ls': FakeFileType('-rwxr-xr-x', 'root', 'root', 4444, 'Mar\t14\t2016')
        }),
        'root': FakeDirType('rwx------', 'root', 'root', 'Mar\t12\t02:31'),
        'tmp': FakeDirType('rwxrwxrwt', 'root', 'root', 'Mar\t12\t02:31')
    }

    def show_welcome_message(self):
        print(self.WELCOME_MESSAGE)
        time.sleep(1)

    def get_command(self):
        if self.__WORK_DIR == self.HOME_DIR:
            workdir = '~'
        else:
            workdir = self.__WORK_DIR
        while True:
            command = input(self.BASH_PREFIX.format(workdir))
            if command == '':
                continue
            return command
    
    def show_command_not_found(self, command):
        print('-bash: {}: command not found'.format(command))

    def bash_cd(self, command):
        file_not_found_message = '-bash: cd: {}: No such file or directory'
        not_dir_message = '-bash: cd: {}: Not a directory'
        command_length = len(command)
        if command_length == 1:
            self.__WORK_DIR = self.HOME_DIR
        elif command_length == 2:
            user_input = command[1]
            full_path = self.get_full_path(command[1])
            full_path_split = full_path[1:].split('/')
            now_dictionary = None
            if full_path == '/':
                self.__WORK_DIR = '/'
                return
            for i in full_path_split:
                if now_dictionary == None:
                    now_dictionary = self.FILES_LIST
                check_result = self.check_dir(now_dictionary, i)
                if check_result == None:
                    print(file_not_found_message.format(user_input))
                    return
                elif check_result == False:
                    print(not_dir_message.format(user_input))
                    return
                else:
                    now_dictionary = check_result
            self.__WORK_DIR = full_path
        else:
            print('-bash: cd: too many arguments')

    def check_dir(self, now_dictionary, target):
        try:
            tmp_dir = now_dictionary[target]
            if type(tmp_dir) != FakeDirType:
                return False
            return tmp_dir.FILES
        except KeyError:
            return None
    
    def get_dir(self, target):
        full_path = self.get_full_path(target)
        full_path_split = full_path[1:].split('/')
        now_dictionary = None
        if full_path == '/':
            self.__WORK_DIR = '/'
            return self.FILES_LIST
        for i in full_path_split:
            if now_dictionary == None:
                now_dictionary = self.FILES_LIST
            check_result = self.check_dir(now_dictionary, i)
            if check_result == None:
                return None
            elif check_result == False:
                return False
            else:
                now_dictionary = check_result
        return now_dictionary

    def get_full_path(self, path):
        if path[0:1] == '/':
            return path
        elif path[0:2] == './':
            return self.__WORK_DIR + path[1:]
        elif path == '.':
            return self.__WORK_DIR
        elif path[0:2] == '..':
            if self.__WORK_DIR == '/':
                return '/'
            if path == '..' or path == '../':
                realpath = '/'
                for i in self.__WORK_DIR[1:].split('/')[:-1]:
                    if realpath == '/':
                        realpath = '/' + i
                    else:
                        realpath += '/' + i
                return realpath
            user_input_split = path[3:].split('/')
            base_path = self.__WORK_DIR[1:].split('/')[:-1]
            real_work_dir = '/'
            for i in base_path:
                if real_work_dir == '/':
                    real_work_dir = '/' + i
                else:
                    real_work_dir += '/' + i
            for i in user_input_split:
                if real_work_dir == '/':
                    real_work_dir = '/' + i
                else:
                    real_work_dir += '/' + i
            return real_work_dir
        else:
            if self.__WORK_DIR == '/':
                return '/' + path
            return self.__WORK_DIR + '/' + path

    def bash_echo(self, command):
        if len(command) == 1:
            print('')
            return
        echo_content = ''
        del command[0]
        for i in command:
            echo_content += i + ' '
        print(echo_content)

    def bash_ls(self, command):
        no_file = 'ls: cannot access \'{}\': No such file or directory'
        command_length = len(command)
        if command_length == 1:
            files_list = self.get_dir(self.__WORK_DIR)
            files = ''
            for k, v in files_list.items():
                files += k + '\t'
            print(files)
            return
        elif command_length == 2:
            userinput = command[1]
            files_list = self.get_dir(userinput)
            if files_list == None:
                print('ls: cannot access \'{}\': No such file or directory'.format(userinput))
                return
            elif files_list == False:
                print(userinput)
                return
            files = ''
            for k, v in files_list.items():
                files += k + '\t'
            print(files)
        else:
            print('-bash: ls: too many arguments')

    def run(self):
        #self.show_welcome_message()
        while True:
            try:
                command = self.get_command().split(' ')
            except KeyboardInterrupt:
                print('')
                continue
            if command[0] == 'exit':
                return
            elif command[0] == 'cd':
                self.bash_cd(command)
                continue
            elif command[0] == 'echo':
                self.bash_echo(command)
                continue
            elif command[0] == 'ls':
                self.bash_ls(command)
                continue
            elif command[0] == 'pwd':
                print(self.__WORK_DIR)
                continue
            else:
                self.show_command_not_found(command[0])


if __name__ == '__main__':
    FakeBash().run()