[PATCH v2 1/2] get_maintainer: add patch-only keyword-matching

[Justin Stitt <justinstitt@google.com>]

Add the "D:" type which behaves the same as "K:" but will only match
content present in a patch file.

To illustrate:

Imagine this entry in MAINTAINERS:

NEW REPUBLIC
M: Han Solo <hansolo@rebelalliance.co>
W: https://www.jointheresistance.org
D: \bstrncpy\b

Our maintainer, Han, will only be added to the recipients if a patch
file is passed to get_maintainer (like what b4 does):
$ ./scripts/get_maintainer.pl 0004-some-change.patch

If the above patch has a `strncpy` present in the subject, commit log or
diff then Han will be to/cc'd.

However, in the event of a file from the tree given like:
$ ./scripts/get_maintainer.pl ./lib/string.c

Han will not be noisily to/cc'd (like a K: type would in this
circumstance)

Signed-off-by: Justin Stitt <justinstitt@google.com>
---
 MAINTAINERS               |  5 +++++
 scripts/get_maintainer.pl | 12 ++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index b19995690904..94e431daa7c2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -59,6 +59,11 @@ Descriptions of section entries and preferred order
 	      matches patches or files that contain one or more of the words
 	      printk, pr_info or pr_err
 	   One regex pattern per line.  Multiple K: lines acceptable.
+  D: *Diff content regex* (perl extended) pattern match that applies only to
+     patches and not entire files (e.g. when using the get_maintainers.pl
+     script).
+     Usage same as K:.
+
 
 Maintainers List
 ----------------
diff --git a/scripts/get_maintainer.pl b/scripts/get_maintainer.pl
index ab123b498fd9..a3e697926ddd 100755
--- a/scripts/get_maintainer.pl
+++ b/scripts/get_maintainer.pl
@@ -342,6 +342,7 @@ if ($tree && !top_of_kernel_tree($lk_path)) {
 
 my @typevalue = ();
 my %keyword_hash;
+my %patch_keyword_hash;
 my @mfiles = ();
 my @self_test_info = ();
 
@@ -369,8 +370,10 @@ sub read_maintainer_file {
 		    $value =~ s@([^/])$@$1/@;
 		}
 	    } elsif ($type eq "K") {
-		$keyword_hash{@typevalue} = $value;
-	    }
+          $keyword_hash{@typevalue} = $value;
+	    } elsif ($type eq "D") {
+          $patch_keyword_hash{@typevalue} = $value;
+      }
 	    push(@typevalue, "$type:$value");
 	} elsif (!(/^\s*$/ || /^\s*\#/)) {
 	    push(@typevalue, $line);
@@ -607,6 +610,11 @@ foreach my $file (@ARGV) {
 			push(@keyword_tvi, $line);
 		    }
 		}
+    foreach my $line(keys %patch_keyword_hash) {
+      if ($patch_line =~ m/${patch_prefix}$patch_keyword_hash{$line}/x) {
+        push(@keyword_tvi, $line);
+      }
+    }
 	    }
 	}
 	close($patch);

-- 
2.42.0.582.g8ccd20d70d-goog