[PATCH 2/2] viewdiff: stricter highlighting and linkification check

[Eric Wong <e@yhbt.net>]

Sometimes senders draw ASCII tables and such which we
get fooled into attempting highlighting and diffstat
anchoring.

We now require 3 consecutive diff header lines:

	/^--- /, /^\Q+++\E /, and /^@@ /

to enable diff highlighting (whether generated with git or not).
The presence of a line matching /^diff / is not sufficient or
even useful to us for highlighting diffs, since that could just
be part of a line-wrapped sentence.

However, we'll now check for the presence of a line matching
/^diff --git / before enabling diffstat anchors.  Otherwise
cover letters for a patch series may fool us into creating
anchors for diffstats.
---
 lib/PublicInbox/View.pm     | 7 +++++--
 lib/PublicInbox/ViewDiff.pm | 4 +++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 5144a130..f7a8ae32 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -536,11 +536,14 @@ sub add_text_body { # callback for msg_iter
 	# always support diff-highlighting, but we can't linkify hunk
 	# headers for solver unless some coderepo are configured:
 	my $diff;
-	if ($s =~ /^(?:diff|---|\+{3}) /ms) {
+	if ($s =~ /^--- [^\n]+\n\+{3} [^\n]+\n@@ /ms) {
 		# diffstat anchors do not link across attachments or messages:
 		$idx[0] = $upfx . $idx[0] if $upfx ne '';
 		$ctx->{-apfx} = join('/', @idx);
-		$ctx->{-anchors} = {}; # attr => filename
+
+		# do attr => filename mappings for diffstats in git diffs:
+		$ctx->{-anchors} = {} if $s =~ /^diff --git /sm;
+
 		$diff = 1;
 		delete $ctx->{-long_path};
 		my $spfx;
diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index 34df8ad4..6fe9a0d7 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -165,10 +165,12 @@ sub diff_before_or_after ($$) {
 	my ($ctx, $x) = @_;
 	my $linkify = $ctx->{-linkify};
 	my $dst = $ctx->{obuf};
+	my $anchors = exists($ctx->{-anchors}) ? 1 : 0;
 	for my $y (split(/(^---\n)/sm, $$x)) {
 		if ($y =~ /\A---\n\z/s) {
 			$$dst .= "---\n"; # all HTML is "\r\n" => "\n"
-		} elsif ($y =~ /^ [0-9]+ files? changed, /sm) {
+			$anchors |= 2;
+		} elsif ($anchors == 3 && $y =~ /^ [0-9]+ files? changed, /sm) {
 			# ok, looks like a diffstat, go line-by-line:
 			for my $l (split(/^/m, $y)) {
 				if ($l =~ /^ (.+)( +\| .*\z)/s) {