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Re: Contents of file changed while application is reading it

From Richard Kettlewell <invalid@invalid.invalid>
Newsgroups comp.os.linux.misc
Subject Re: Contents of file changed while application is reading it
Date 2023-03-04 11:22 +0000
Organization terraraq NNTP server
Message-ID <wwvmt4sn4lp.fsf@LkoBDZeT.terraraq.uk> (permalink)
References (14 earlier) <dYudnfNen9mG55z5nZ2dnZfqn_ednZ2d@earthlink.com> <ttsejp$279gm$64@dont-email.me> <qPadnQSthu_CfJ_5nZ2dnZfqn_ednZ2d@earthlink.com> <wwvcz5o7sfd.fsf@LkoBDZeT.terraraq.uk> <ttv5cm$27bbi$63@dont-email.me>

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The Natural Philosopher <tnp@invalid.invalid> writes:
> On 04/03/2023 09:54, Richard Kettlewell wrote:
>> If it’s ‘volatile char *TheStr’ then this assumption is prohibited -
>> the string “may be modified in ways unknown to the implementation” in
>> the language of the spec. (The intention is support memory-mapped
>> hardware.)  In this case a compiler must call strlen every time round
>> the loop (and indeed GCC and Clang do so).
>
> In my limited experience., one uses 'volatile' when e.g. a buffer is
> being replenished by e.g an interrupt service routine, whose action
> lies outside the thread that the compiler is aware of. I guess that is
> sorta 'memory mapped hardware' but not I suspect in the manner in
> which you were thinking

It’s suitable for coping with signals/interrupts too, yes.

The point that sometimes causes confusion is that it’s _not_ suitable
for managing concurrent access from multiple threads.

-- 
https://www.greenend.org.uk/rjk/

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Thread

Contents of file changed while application is reading it Clark Smith <noaddress@nowhere.net> - 2023-02-26 18:52 +0000
  Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-02-26 19:20 +0000
  Re: Contents of file changed while application is reading it Robert Heller <heller@deepsoft.com> - 2023-02-26 21:45 +0000
    Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-26 23:05 +0100
      Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:38 +0000
    Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:32 +0000
      Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-26 19:06 -0500
        Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 00:26 +0000
          Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-26 20:48 -0500
          Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 09:03 +0000
            Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 09:58 +0000
              Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:16 +0100
              Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 15:20 +0000
        Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 10:34 +0100
          Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 09:49 +0000
            Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:13 +0100
          Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 10:02 +0000
            Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:13 +0100
              Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 10:17 +0000
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-27 12:27 -0500
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 19:19 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-27 21:46 -0500
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-28 13:33 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-28 10:49 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-28 16:21 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:05 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-01 21:57 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 22:53 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-02 19:06 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-02 23:08 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-03 05:23 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 09:36 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-03-03 11:19 +0100
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-03 15:58 +0000
                Re: Contents of file changed while application is reading it "Carlos E. R." <robin_listas@es.invalid> - 2023-03-03 18:47 +0100
                Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-03-04 16:24 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-03-04 18:40 +0100
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 18:44 +0000
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-04 01:25 +0000
                Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-03-04 16:21 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-04 23:55 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-05 05:35 +0000
                Re: Contents of file changed while application is reading it Allodoxaphobia <trepidation@example.net> - 2023-03-05 13:48 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-05 14:01 +0000
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-05 19:16 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 00:43 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 00:42 -0500
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-28 12:01 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:17 -0500
                Re: Contents of file changed while application is reading it Robert Riches <spamtrap42@jacob21819.net> - 2023-02-28 04:13 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-28 13:16 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:32 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-01 10:30 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 22:48 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-02 09:41 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-02 23:39 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 09:28 +0000
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-03-03 12:16 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 01:36 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 07:15 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 02:47 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 01:12 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 06:51 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 03:32 -0500
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-04 09:54 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 10:09 +0000
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-04 11:22 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 11:58 +0000
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-05 16:43 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-06 09:20 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-04 20:24 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-05 13:40 +0000
                Re: Contents of file changed while application is reading it Dan Espen <dan1espen@gmail.com> - 2023-03-05 11:29 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 01:21 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 01:06 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-06 09:28 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 08:54 -0500
  Re: Contents of file changed while application is reading it Dan Espen <dan1espen@gmail.com> - 2023-02-26 17:35 -0500
    Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:39 +0000
      Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-26 22:42 -0500
    Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 10:45 +0100
  Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:31 +0000

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