linux-kernel - RE: Question about select and poll system call

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Message-ID: <bc2ce748111d4699a765132a17a14522@AcuMS.aculab.com>
Date:   Thu, 16 Mar 2023 09:34:02 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'richard clark' <richard.xnu.clark@...il.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>
Subject: RE: Question about select and poll system call

From: richard clark
> Sent: 16 March 2023 00:57
> 
> On Wed, Mar 15, 2023 at 4:59 PM David Laight <David.Laight@...lab.com> wrote:
> >
> > > 2. Can we unify the two different system calls? For example, using
> > > poll(...) to implement the frontend select call(...), is there
> > > something I'm missing for current implementation? The Cons and Pros,
> > > etc
> >
> > The underlying code that implements them is common.
> >
> > Beware that the glibc select() wrappers have their own limit
> > on the highest fd.
> > Exceeding that limit (probably 1024) will cause buffer overruns
> > in the application (One of the Android apps I uses crashes that way).
> 
> Ah, interesting. Seems glibc doesn't make that limit from my testing
> code snippet in last email...

Look at the FD_SET() macros....

	David

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