[RFC PATCH 1/2] checkpatch: Correctly detect git commit references that span 3 lines

[Andrew Donnellan <andrew.donnellan@au1.ibm.com>]

If a patch contains a commit reference that happens to span 3 lines, e.g.:

===
With the optimizations for TLB invalidation from commit 0cef77c7798a
("powerpc/64s/radix: flush remote CPUs out of single-threaded
mm_cpumask"), the scope of a TLBI (global vs. local) can now be
influenced by the value of the 'copros' counter of the memory context.
===

checkpatch will return a GIT_COMMIT_ID error even though the reference
actually follows the correct format.

Fix the GIT_COMMIT_ID test so it can match against a reference that spans 3
lines.

Reported-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

---

Sending this as an RFC because I don't actually know how to Perl or regex,
this whole test looks pretty gross and this patch just makes it gross-er,
and it's only lightly tested. Suggestions on how to do this more neatly are
welcome.

We currently have checkpatch running on every incoming patch on
linuxppc-dev, and we've already hit this bug at least twice in the past
couple of weeks.
---
 scripts/checkpatch.pl | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 447857ffaf6b..aca4d758112a 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2669,27 +2669,60 @@ sub process {
 			} elsif ($line =~ /\b([0-9a-f]{12,40})\b/i) {
 				$orig_commit = lc($1);
 			}
-
 			$short = 0 if ($line =~ /\bcommit\s+[0-9a-f]{12,40}/i);
 			$long = 1 if ($line =~ /\bcommit\s+[0-9a-f]{41,}/i);
 			$space = 0 if ($line =~ /\bcommit [0-9a-f]/i);
 			$case = 0 if ($line =~ /\b[Cc]ommit\s+[0-9a-f]{5,40}[^A-F]/);
+
 			if ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)"\)/i) {
+				# Reference fits on 1 line
 				$orig_desc = $1;
 				$hasparens = 1;
 			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s*$/i &&
 				 defined $rawlines[$linenr] &&
 				 $rawlines[$linenr] =~ /^\s*\("([^"]+)"\)/) {
+				# line 1: 'commit <hash>',
+				# line 2: '("description")'
 				$orig_desc = $1;
 				$hasparens = 1;
 			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("[^"]+$/i &&
 				 defined $rawlines[$linenr] &&
 				 $rawlines[$linenr] =~ /^\s*[^"]+"\)/) {
+				# line 1: 'commit <hash> ("description',
+				# line 2: 'description continued")'
 				$line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)$/i;
 				$orig_desc = $1;
 				$rawlines[$linenr] =~ /^\s*([^"]+)"\)/;
 				$orig_desc .= " " . $1;
 				$hasparens = 1;
+			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s*$/i &&
+				 defined $rawlines[$linenr] &&
+				 defined $rawlines[$linenr + 1] &&
+				 $rawlines[$linenr] =~ /^\s*\("[^"]+/ &&
+				 $rawlines[$linenr + 1] =~ /^\s*[^"]+"\)/) {
+				# line 1: 'commit <hash>',
+				# line 2: '("description'
+				# line 3: 'description continued")'
+				$rawlines[$linenr] =~ /^\s*\("([^"]+)/;
+				$orig_desc = $1;
+				$rawlines[$linenr + 1] =~ /^\s*([^"]+)"\)/;
+				$orig_desc .= " " . $1;
+				$hasparens = 1;
+			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("[^"]+$/i &&
+				 defined $rawlines[$linenr] &&
+				 defined $rawlines[$linenr + 1] &&
+				 $rawlines[$linenr] =~ /^\s*[^"]+$/ &&
+				 $rawlines[$linenr + 1] =~ /^\s*[^"]+"\)/) {
+				# line 1: 'commit <hash> ("description',
+				# line 2: 'description continued'
+				# line 3: 'description continued")'
+				$line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)$/i;
+				$orig_desc = $1;
+				$rawlines[$linenr] =~ /^\s*([^"]+)$/;
+				$orig_desc .= " " . $1;
+				$rawlines[$linenr + 1] =~ /^\s*([^"]+)"\)/;
+				$orig_desc .= " " . $1;
+				$hasparens = 1;
 			}
 
 			($id, $description) = git_commit_info($orig_commit,
-- 
2.11.0