From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: fgets() doesn't call fsync() before getting input
Date: Thu, 21 Feb 2019 10:22:43 -0500 [thread overview]
Message-ID: <20190221152243.GF23599@brightrain.aerifal.cx> (raw)
In-Reply-To: <CAEfvv4+qGgm+RuJNnurBW1yOErftNUrvDE1HuwKvUNyU6P936g@mail.gmail.com>
On Thu, Feb 21, 2019 at 10:09:03AM -0500, James Larrowe wrote:
> I'm writing a program that prints a dialogue to the screen and then asks
> for input. In musl, the dialogue does not show before fgets() is called,
> however in glibc it does. That causes a blank prompt and also some
> confusion. Attached is a minimal example and a log.
This difference is intentional. The specification allows but does not
require that attempting to read from a line-buffered input stream
causes all line-buffered output streams to be flushed. This behavior
was somewhat convenient for old-style input-prompt idioms, but it
doesn't scale with large numbers of files open and deadlocks with some
multi-threaded usage. The portable solution here for applications is
to fflush (not fsync) the particular stream you want flushed.
Rich
next prev parent reply other threads:[~2019-02-21 15:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-21 15:09 James Larrowe
2019-02-21 15:22 ` Rich Felker [this message]
2019-02-21 16:31 ` A. Wilcox
2019-02-21 17:07 ` Rich Felker
2019-02-21 19:24 ` Laurent Bercot
2019-02-21 20:16 ` James Larrowe
2019-02-21 20:44 ` Rich Felker
2019-02-22 5:04 ` Markus Wichmann
2019-02-25 13:10 ` James Larrowe
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