[New-bugs-announce] [issue1703] getpass broken in Py3k: must flush()

[Philip Jenvey]

New submission from Philip Jenvey:

getpass (in particular _raw_input, used by unix_getpass and 
default_getpass) prints out a password prompt to a stream (by default 
stdout) but doesn't flush that stream. It assumes calling 
sys.stdin.readline() to read the password causes stdout to be flushed 
(probably a libc file buffering behavior)

This is a problem in Py3k where file buffering is done by Python; 
getpass needs to manually flush the stream it prints the prompt to. 
Otherwise the prompt isn't printed until after the password is entered 
e.g.:

Python 3.0a2 (py3k:59601, Dec 27 2007, 14:28:14) 
[GCC 4.1.3 20071209 (prerelease) (Debian 4.1.2-18)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import getpass
>>> getpass.getpass()

<no prompt is printed, i type 'foo\n', and only afterwards is the prompt 
printed>

Password: 
'foo'
>>>

Windows doesn't use _raw_input so it wouldn't see this issue.

Attached is a patch to flush the stream. There's no getpass tests so I 
didn't get around to creating one for this issue. Ideally we'd test 
getpass via spawning a python subprocess and ensuring its I/O looked 
correct.

This was noticed on Jython as its file object is now based off Py3k's

----------
components: Library (Lib)
files: getpass_flush-r59601.diff
messages: 59011
nosy: pjenvey
severity: normal
status: open
title: getpass broken in Py3k: must flush()
versions: Python 3.0
Added file: http://bugs.python.org/file9031/getpass_flush-r59601.diff

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<http://bugs.python.org/issue1703>
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