[Python-Dev] getpass and stdin

Shaya Potter spotter at cs.columbia.edu
Sun Feb 24 19:02:44 CET 2008

[please cc me on responses]

I was wondering if getpass could be changed to enable piped stdin to work.

For instance, the getmail program can read my email password in via 
stdin using getpass functionality.

However, if I do

echo password | getmail4

it will fail due to stdin not being a terminal and therefore not being 
able to do a old = termios.tcgetattr(fd) on it.

 From what I can tell, the point of this is to only to prevent echoing 
the password, which isn't a problem in the echo case I give (especially 
if using bash, then it wont even be on the cmdline when run from a 
script as it's a builtin, script can also read in the password and store 
it in memory).

currently the code is

def unix_getpass(prompt='Password: '):
     """Prompt for a password, with echo turned off.

     Restore terminal settings at end.

         fd = sys.stdin.fileno()
         return default_getpass(prompt)

     old = termios.tcgetattr(fd)     # a copy to save
     new = old[:]

     new[3] = new[3] & ~termios.ECHO # 3 == 'lflags'
         termios.tcsetattr(fd, termios.TCSADRAIN, new)
         passwd = _raw_input(prompt)
         termios.tcsetattr(fd, termios.TCSADRAIN, old)

     return passwd

it would seem that if the tcgetattr() line is moved into the initial 
try, my echo case would work as expected (as it would fail, but be 
caught and then just run default_getpass() (which should just read it 
from stdin).

Is there any reason not to do it this way?

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