[PATCH] checkpatch: Improve get_quoted_string for TRACE_EVENT macros

[Joe Perches]

The get_quoted_string function does not expect invalid arguments.

The $stat test can return non-statements for complicated macros
like TRACE_EVENT.

Allow the $stat block and test for vsprintf misuses to exceed
the actual block lenght and possibly test invalid lines by
validating the arguments of get_quoted_string.

return "" if either get_quoted_string argument is undefined.

Miscellanea:

o Properly align the comment for the vsprintf extension test

Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>
Reported-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 scripts/checkpatch.pl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 16e542f4e027..5a6cef8f2376 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1298,6 +1298,7 @@ sub sanitise_line {
 sub get_quoted_string {
 	my ($line, $rawline) = @_;
 
+	return "" if (!defined($line) || !defined($rawline));
 	return "" if ($line !~ m/($String)/g);
 	return substr($rawline, $-[0], $+[0] - $-[0]);
 }
@@ -5817,7 +5818,7 @@ sub process {
 			}
 		}
 
-		# check for vsprintf extension %p<foo> misuses
+# check for vsprintf extension %p<foo> misuses
 		if ($^V && $^V ge 5.10.0 &&
 		    defined $stat &&
 		    $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s &&
-- 
2.15.0