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From:   Chuhong Yuan <hslester96@gmail.com>
Date:   Fri, 2 Aug 2019 23:21:14 +0800
Message-ID: <CANhBUQ23mc8e+RhG48Vcb_xNUcBuGACMN6SuAJzTom5yUirXgA@mail.gmail.com>
Subject: Re: [PATCH] Documentation/checkpatch: Prefer str_has_prefix over strncmp
To:     Jonathan Corbet <corbet@lwn.net>
Cc:     Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>,
        linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
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Jonathan Corbet <corbet@lwn.net> =E4=BA=8E2019=E5=B9=B48=E6=9C=882=E6=97=A5=
=E5=91=A8=E4=BA=94 =E4=B8=8B=E5=8D=889:38=E5=86=99=E9=81=93=EF=BC=9A
>
> On Fri,  2 Aug 2019 14:25:37 +0800
> Chuhong Yuan <hslester96@gmail.com> wrote:
>
> > Add strncmp() to Documentation/process/deprecated.rst since
> > using strncmp() to check whether a string starts with a
> > prefix is error-prone.
> > The safe replacement is str_has_prefix().
>
> Is that the *only* use of strncmp()?

This is not the only use of strncmp().
Maybe add a case description like strncpy() is more precise?
For example, "strncmp() on string prefix".

>
> > Also add check to the newly introduced deprecated_string_apis
> > in checkpatch.pl.
> >
> > This patch depends on patch:
> > "Documentation/checkpatch: Prefer stracpy/strscpy over
> > strcpy/strlcpy/strncpy."
> >
> > Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> > ---
> >  Documentation/process/deprecated.rst | 8 ++++++++
> >  scripts/checkpatch.pl                | 1 +
> >  2 files changed, 9 insertions(+)
> >
> > diff --git a/Documentation/process/deprecated.rst b/Documentation/proce=
ss/deprecated.rst
> > index 56280e108d5a..22d3f0dbcf61 100644
> > --- a/Documentation/process/deprecated.rst
> > +++ b/Documentation/process/deprecated.rst
> > @@ -109,6 +109,14 @@ the given limit of bytes to copy. This is ineffici=
ent and can lead to
> >  linear read overflows if a source string is not NUL-terminated. The
> >  safe replacement is stracpy() or strscpy().
> >
> > +strncmp()
> > +---------
> > +:c:func:`strncmp` is often used to test if a string starts with a pref=
ix
>
> Please don't use :c:func: anymore; just say strncmp() and the right thing=
s
> will happen.
>

I will revise this in the next version.

Regards,
Chuhong

> Thanks,
>
> jon