On Wed, 2021-10-13 at 09:15 +0300, Dan Carpenter wrote:
> On Sun, Oct 10, 2021 at 09:45:30AM -0700, Joe Perches wrote:
> > Perhaps too many developers do not know that using '%#<width>x'
> > in printf output _includes_ the 0x prefix in the output width.
> >
>
> This is a good point. Presumably you're going to add it to checkpatch.pl?
Yeah. Something like the below:
> I looked at '%#04x' and you would think those would all be printing char
> types but some are printing shorts. :/ It's harder to deal with that
> because 50% are correct from the tiny sample I looked at.
That'd be difficult as checkpatch doesn't know format argument types.
---
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index c27d2312cfc30..97deae9dafcdc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6703,7 +6703,7 @@ sub process {
}
}
-# check for vsprintf extension %p<foo> misuses
+# check for vsprintf format and extension %p<foo> misuses
if ($perl_version_ok &&
defined $stat &&
$stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
@@ -6720,6 +6720,18 @@ sub process {
my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
$fmt =~ s/%%//g;
+ # check for %# (0x prefixed) width too small
+ while ($fmt =~ /(%#0?([123])([xX]))/g) {
+ my $hex = $1;
+ my $width = $2;
+ my $case = $3;
+ if (!defined($stat_real)) {
+ $stat_real = get_stat_real($linenr, $lc);
+ }
+ WARN("VSPRINTF_HEX_WIDTH",
+ "hex specifier '$hex' - output width '$width' does not include the '0$case' prefix, width should be probably be increased\n" . "$here\n$stat_real");
+ }
+ pos($fmt) = 0;
while ($fmt =~ /(\%[\*\d\.]*p(\w)(\w*))/g) {
$specifier = $1;
$extension = $2;
