[PATCH] scripts/checkpatch.pl: add a check for the patch level (patch -p<num>)

[Borislav Petkov <bbpetkov@yahoo.de>]

Being bitten by this several times myself here's a quick hack for checking the patch
level of the diffs in a patch file. It works only when checkpatch.pl is called
from within the kernel tree.

---
Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>

--
 scripts/checkpatch.pl |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 579f50f..b1329fc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -653,6 +653,18 @@ sub CHK {
 	}
 }
 
+sub check_patchlevel {
+
+	my ($path) = @_;
+	$path =~ s![^/]*/!!;
+
+	if ($tree) {
+		if (!stat($path)) {
+			WARN("Check the patchlevel (hint: patch option -p)");
+		}
+	}
+}
+
 sub process {
 	my $filename = shift;
 	my @lines = @_;
@@ -713,10 +725,16 @@ sub process {
 #extract the filename as it passes
 		if ($line=~/^\+\+\+\s+(\S+)/) {
 			$realfile=$1;
+
+			if ($realfile) {
+				check_patchlevel($realfile);
+			}
+
 			$realfile =~ s@^[^/]*/@@;
 			$in_comment = 0;
 			next;
 		}
+
 #extract the line range in the file after the patch is applied
 		if ($line=~/^\@\@ -\d+(?:,\d+)? \+(\d+)(,(\d+))? \@\@/) {
 			$is_patch = 1;

-- 
Regards/Gruß,
    Boris.