[patch] select.2: Mention the fd size limitation early and refer to poll

[patch] select.2: Mention the fd size limitation early and refer to poll

[Nikos Mavrogiannopoulos]

[-- Attachment #1: Type: text/plain, Size: 254 bytes --]

That is because the serious limitation of select imposing a limit
on the values a file descriptor can have, is mentioned too late
in the documentation in the notes section. The manpage should
warn and refer to poll as soon as possible.

(patch attached)

[-- Attachment #2: 0001-select.2-Mention-the-fd-size-limitation-early-and-re.patch --]
[-- Type: text/x-patch, Size: 1031 bytes --]

From ca3f1dcc2281ff7bdd14f80a758b31239571d5cd Mon Sep 17 00:00:00 2001
From: Nikos Mavrogiannopoulos <nmav@gnutls.org>
Date: Fri, 29 Jan 2016 10:03:45 +0100
Subject: [PATCH] select.2: Mention the fd size limitation early and refer to
 poll

That is because the serious limitation of select imposing a limit
on the values a file descriptor can have, is mentioned too late
in the documentation in the notes section. The manpage should
warn and refer to poll as soon as possible.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>
---
 man2/select.2 | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/man2/select.2 b/man2/select.2
index 151932e..6c76e1c 100644
--- a/man2/select.2
+++ b/man2/select.2
@@ -91,6 +91,13 @@ perform a corresponding I/O operation (e.g.,
 without blocking, or a sufficiently small
 .BR write (2)).
 .PP
+The file descriptors
+.BR select ()
+can monitor cannot be larger than
+.B FD_SETSIZE.
+.BR poll (2),
+does not have this limitation.
+.PP
 The operation of
 .BR select ()
 and
-- 
2.5.1

Re: [patch] select.2: Mention the fd size limitation early and refer to poll

[Michael Kerrisk (man-pages)]

Hello Nikos,

On 01/29/2016 10:08 AM, Nikos Mavrogiannopoulos wrote:
> That is because the serious limitation of select imposing a limit
> on the values a file descriptor can have, is mentioned too late
> in the documentation in the notes section. The manpage should
> warn and refer to poll as soon as possible.

Agreed. I merged your patch, and in fact even expanded the details
quite a bit to emphasize this issue with (glibc) select()/pselect().

> (patch attached)

Thanks. (But inline patches are much easier to deal with...)

Cheers,

Michael



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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