From: "Kars Mulder" <kerneldev@karsmulder.nl>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Cc: "Pavel Machek" <pavel@ucw.cz>,
linux-kernel@vger.kernel.org,
"Kai-Heng Feng" <kai.heng.feng@canonical.com>
Subject: Re: Writing to a const pointer: is this supposed to happen?
Date: Wed, 24 Jun 2020 17:25:45 +0200 [thread overview]
Message-ID: <1da2-5ef37080-31-6d4cde00@228034409> (raw)
In-Reply-To: <20200624131016.GA1807770@kroah.com>
On Wednesday, June 24, 2020 15:10 CEST, Greg Kroah-Hartman wrote:
> Have you hit any runtime issues with this code doing this? These
> strings should be held in writable memory, right? Or do you see a
> codepath where that is not the case?
I haven't ran into any issues with it; I was just looking at the code
as reference for a patch I'm working on.
I initially assumed that casting a const pointer to non-const and
writing to it would be undefined behaviour, but after reading through
the C99 standard I can't find an unambiguous statement whether it is
undefined behaviour even if the const pointer points to an object that
was originally non-const (like char* -> const char* -> char* casts); it
only says it is undefined behaviour if the object was defined with the
const qualifier.
I should probably stop bothering you with my newbie questions.
next prev parent reply other threads:[~2020-06-24 15:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 11:35 Writing to a const pointer: is this supposed to happen? Kars Mulder
2020-06-23 19:55 ` Pavel Machek
2020-06-24 12:34 ` Kars Mulder
2020-06-24 13:10 ` Greg Kroah-Hartman
2020-06-24 15:25 ` Kars Mulder [this message]
2020-06-27 10:24 ` David Laight
2020-07-01 23:03 ` Kars Mulder
2020-07-02 7:55 ` David Laight
2020-07-02 21:48 ` Kars Mulder
2020-07-03 8:13 ` David Laight
2020-07-03 13:23 ` Kars Mulder
2020-07-04 11:55 ` Pavel Machek
2020-07-05 21:53 ` [PATCH] usb: core: fix quirks_param_set() writing to a const pointer Kars Mulder
2020-07-06 10:34 ` Greg Kroah-Hartman
2020-07-06 12:57 ` Kars Mulder
2020-07-06 13:07 ` Greg Kroah-Hartman
2020-07-06 13:58 ` Kars Mulder
[not found] <CAHp75Ve4O+OmVttjhtKepFWwZLU6tFMx5vNpPVJdB58mcLFm3w@mail.gmail.com>
2020-07-04 20:32 ` Writing to a const pointer: is this supposed to happen? Kars Mulder
2020-07-04 20:54 ` Andy Shevchenko
2020-07-05 18:27 ` Kars Mulder
[not found] <CAHp75Vf9ygQ++DL4ETMy54d=x6oS1qqHLhfyh58f7JCVvM17yA@mail.gmail.com>
2020-07-05 19:38 ` Kars Mulder
[not found] <CAHp75Ve3m=UK9r2o8bDotQWQBLz-fV8CO_VcTmWjdLW1p5wE-w@mail.gmail.com>
2020-07-05 20:48 ` Kars Mulder
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