checkpatch: warn when formats use %Z and suggest %z

vsnprintf extension %Z<foo> is non-standard C.  Suggest the use of %z
instead.

Miscellanea:

 - Correct the misuse of type string PRINTF_0xDECIMAL type strings are
   supposed to be uppercase only. Fix this and add tr/[a-z]/[A-Z] to the
   type check in case I forget this again sometime in the future.

 - Improve the mechanism to find these defects so all 3 current checks
   are done on the format string

[joe@perches.com: correct the misuse of type string PRINTF_0xDECIMAL, improve the mechanism to find these defects]
  Link: http://lkml.kernel.org/r/4e3ad74b0c9dc229b06018a2d79655308ddbbebd.1484014173.git.joe@perches.com
Link: http://lkml.kernel.org/r/20170109235955.GA6787@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 9 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 918259a55f65..baa3c7be04ad 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1848,6 +1848,8 @@ my $prefix = '';
 sub show_type {
         my ($type) = @_;
 
+        $type =~ tr/[a-z]/[A-Z]/;
+
         return defined $use_type{$type} if (scalar keys %use_type > 0);
 
         return !defined $ignore_type{$type};
@@ -5204,18 +5206,27 @@ sub process {
                              "Consecutive strings are generally better as a single string\n" . $herecurr);
                 }
 
-# check for %L{u,d,i} and 0x%[udi] in strings
-                my $string;
+# check for non-standard and hex prefixed decimal printf formats
+                my $show_L = 1; #don't show the same defect twice
+                my $show_Z = 1;
                 while ($line =~ /(?:^|")([X\t]*)(?:"|$)/g) {
-                        $string = substr($rawline, $-[1], $+[1] - $-[1]);
+                        my $string = substr($rawline, $-[1], $+[1] - $-[1]);
                         $string =~ s/%%/__/g;
-                        if ($string =~ /(?<!%)%[\*\d\.\$]*L[udi]/) {
+                        # check for %L
+                        if ($show_L && $string =~ /%[\*\d\.\$]*L([diouxX])/) {
                                 WARN("PRINTF_L",
-                                     "\%Ld/%Lu are not-standard C, use %lld/%llu\n" . $herecurr);
-                                last;
-                        }
-                        if ($string =~ /0x%[\*\d\.\$\Llzth]*[udi]/) {
-                                ERROR("PRINTF_0xDECIMAL",
+                                     "\%L$1 is non-standard C, use %ll$1\n" . $herecurr);
+                                $show_L = 0;
+                        }
+                        # check for %Z
+                        if ($show_Z && $string =~ /%[\*\d\.\$]*Z([diouxX])/) {
+                                WARN("PRINTF_Z",
+                                     "%Z$1 is non-standard C, use %z$1\n" . $herecurr);
+                                $show_Z = 0;
+                        }
+                        # check for 0x<decimal>
+                        if ($string =~ /0x%[\*\d\.\$\Llzth]*[diou]/) {
+                                ERROR("PRINTF_0XDECIMAL",
                                       "Prefixing 0x with decimal output is defective\n" . $herecurr);
                         }
                 }