solution for password visual IOput on console

又战斗到天明了。
成果：

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import termios, sys, os
TERMIOS = termios

def getch():
        fd = sys.stdin.fileno()
        old = termios.tcgetattr(fd)
        new = termios.tcgetattr(fd)
        new[3] = new[3] & ~TERMIOS.ICANON & ~TERMIOS.ECHO
        new[6][TERMIOS.VMIN] = 1
        new[6][TERMIOS.VTIME] = 0
        termios.tcsetattr(fd, TERMIOS.TCSANOW, new)
        c = None
        try:
                c = os.read(fd, 1)
        finally:
                termios.tcsetattr(fd, TERMIOS.TCSAFLUSH, old)
        return c

def passwd():
    chars = ''
    while True:
        newChar = getch()
        if newChar in '=\r\n': # 如果是换行，则输入结束              
             break
        elif newChar == '': # 如果是退格，则删除密码末尾一位并且删除一个星号  
             if chars:
                    chars = chars[:-1]
                    sys.stdout.write('\b \b')
                    sys.stdout.flush()
        else:
#            chars.append(newChar)
            chars += newChar
            sys.stdout.write('*')
            sys.stdout.flush()
    return ('\n'+chars)

'''
    password=''
    while 1:
        ch = getch()
        if ch == '\b':
            if password:
                password = password[:-1]
                sys.stdout.write('\b \b')
                sys.stdout.flush()
            else:
                continue
        elif ch == '\n':
                sys.stdout.write(os.linesep)
                return password
        else:
            password += ch
        sys.stdout.write('*')
        sys.stdout.flush()
'''
print passwd()