On Thu, 2024-04-11 at 22:01 +0200, Christophe JAILLET wrote:
> Le 08/04/2024 à 22:53, Justin Stitt a écrit :
> > I am going to quote Lee Jones who has been doing some snprintf ->
> > scnprintf refactorings:
> >
> > "There is a general misunderstanding amongst engineers that
> > {v}snprintf() returns the length of the data *actually* encoded into the
> > destination array. However, as per the C99 standard {v}snprintf()
> > really returns the length of the data that *would have been* written if
> > there were enough space for it. This misunderstanding has led to
> > buffer-overruns in the past. It's generally considered safer to use the
> > {v}scnprintf() variants in their place (or even sprintf() in simple
> > cases). So let's do that."
> >
> > To help prevent new instances of snprintf() from popping up, let's add a
> > check to checkpatch.pl.
> >
> > Suggested-by: Finn Thain <fth...@linux-m68k.org>
> > Signed-off-by: Justin Stitt <justinst...@google.com>
> > ---
> > Changes in v4:
> > - also check for vsnprintf variant (thanks Bill)
> > - Link to v3:
> > https://lore.kernel.org/r/20240315-snprintf-checkpatch-v3-1-a451e7664...@google.com
> >
> > Changes in v3:
> > - fix indentation
> > - add reference link (https://github.com/KSPP/linux/issues/105) (thanks Joe)
> > - Link to v2:
> > https://lore.kernel.org/r/20240221-snprintf-checkpatch-v2-1-9baeb59da...@google.com
> >
> > Changes in v2:
> > - Had a vim moment and deleted a character before sending the patch.
> > - Replaced the character :)
> > - Link to v1:
> > https://lore.kernel.org/r/20240221-snprintf-checkpatch-v1-1-3ac5025b5...@google.com
> > ---
> > From a discussion here [1].
> >
> > [1]:
> > https://lore.kernel.org/all/0f9c95f9-2c14-eee6-7faf-635880edc...@linux-m68k.org/
> > ---
> > scripts/checkpatch.pl | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 9c4c4a61bc83..a0fd681ea837 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -7012,6 +7012,12 @@ sub process {
> > "Prefer strscpy, strscpy_pad, or __nonstring over
> > strncpy - see: https://github.com/KSPP/linux/issues/90\n"; . $herecurr);
> > }
> >
> > +# {v}snprintf uses that should likely be {v}scnprintf
> > + if ($line =~ /\b(v|)snprintf\s*\(\s*/) {
>
> Hi,
>
> for my understanding, what is the purpose of the 2nd "\s*"?
> IMHO, it could be just removed.
It could.
# {v}snprintf uses that should likely be {v}scnprintf
if ($line =~ /\b((v?)snprintf)\s*\(/) {
WARN("SNPRINTF",
"Prefer ${2}scnprintf over $1 - see:
https://github.com/KSPP/linux/issues/105\n"; . $herecurr);
}
Though I also think it's better to use lore rather than github
