Date: Sat, 30 May 2015 08:44:46 +0300 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: [john-core] Getting John's stdout unbuffered for Johnny On Wed, May 27, 2015 at 09:56:23PM +0200, magnum wrote: > On 2015-05-27 20:57, Shinnok wrote: > >NB: What I find weird about JtR is that by default, it treats input > >as a tty(and if not tty then defaults to reading password candidates) > > As far as I'm aware it treats input as a TTY if it is indeed a TTY, > nothing weird about that. It doesn't default to reading candidates, > there's an option for that. I am with magnum on this. > I haven't ever experienced any problems with stdout buffering, perhaps > it's somewhat different under Windows? No, what Shinnok describes about stdout buffering is actually the same on Unix. By default, libc has stdout line buffered when outputting to a tty and fully buffered when not. http://www.pixelbeat.org/programming/stdio_buffering/ http://stackoverflow.com/questions/13932932/why-does-stdout-need-explicit-flushing-when-redirected-to-file > >and output as standard buffered stdout. This discussion will probably > >evolve towards trying to be more flexible on that front so that > >wrappers(like Johnny) can properly communicate with it. > > My general feeling about this is you shouldn't try to use stdin/stdout > for things they're not designed to do. If we're about to change JtR > code, why not add a proper interface of some sort, intead of fflush > bodges? How hard would that be? (that is a sincere question, not irony). This makes sense. However, I don't mind changing stdout to always be line-buffered. This means JtR will run slower when someone redirects its stdout to a disk file, but that's not typical and when someone does it for some weird reason they quite possibly actually want it to be merely line-buffered. I think setting it to unbuffered is overkill. Shinnok, just let me know what the Johnny team decides on this. If you ask me to, I think I'll add a call to: setvbuf(stdout, NULL, _IOLBF, 0); to john.c: john_init(). It is important to keep stdout with its default buffering when john is invoked via one of the un* symlinks, since they're commonly used with stdout pointing at a disk file. Alexander
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