Merge branch 'jc/doc-lint'

Find common mistakes when writing gitlink: in our documentation and
drive the check from "make check-docs".

I am not entirely happy with the way the script chooses what input
file to validate, but it is not worse than not having anything, so
let's move it forward and have the logic improved later when people
care about it deeply.

* jc/doc-lint:
  ci: validate "linkgit:" in documentation

3 files changed, 76 insertions, 0 deletions

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 3e39e2815b..f6e288bc63 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -204,6 +204,7 @@ ifndef V
 	QUIET_DBLATEX	= @echo '   ' DBLATEX $@;
 	QUIET_XSLTPROC	= @echo '   ' XSLTPROC $@;
 	QUIET_GEN	= @echo '   ' GEN $@;
+	QUIET_LINT	= @echo '   ' LINT $@;
 	QUIET_STDERR	= 2> /dev/null
 	QUIET_SUBDIR0	= +@subdir=
 	QUIET_SUBDIR1	= ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \
@@ -427,4 +428,7 @@ quick-install-html: require-htmlrepo
 print-man1:
 	@for i in $(MAN1_TXT); do echo $$i; done
 
+lint-docs::
+	$(QUIET_LINT)$(PERL_PATH) lint-gitlink.perl
+
 .PHONY: FORCE
diff --git a/Documentation/lint-gitlink.perl b/Documentation/lint-gitlink.perl
new file mode 100755
index 0000000000..476cc30b83
--- /dev/null
+++ b/Documentation/lint-gitlink.perl
@@ -0,0 +1,71 @@
+#!/usr/bin/perl
+
+use File::Find;
+use Getopt::Long;
+
+my $basedir = ".";
+GetOptions("basedir=s" => \$basedir)
+	or die("Cannot parse command line arguments\n");
+
+my $found_errors = 0;
+
+sub report {
+	my ($where, $what, $error) = @_;
+	print "$where: $error: $what\n";
+	$found_errors = 1;
+}
+
+sub grab_section {
+	my ($page) = @_;
+	open my $fh, "<", "$basedir/$page.txt";
+	my $firstline = <$fh>;
+	chomp $firstline;
+	close $fh;
+	my ($section) = ($firstline =~ /.*\((\d)\)$/);
+	return $section;
+}
+
+sub lint {
+	my ($file) = @_;
+	open my $fh, "<", $file
+		or return;
+	while (<$fh>) {
+		my $where = "$file:$.";
+		while (s/linkgit:((.*?)\[(\d)\])//) {
+			my ($target, $page, $section) = ($1, $2, $3);
+
+			# De-AsciiDoc
+			$page =~ s/{litdd}/--/g;
+
+			if ($page !~ /^git/) {
+				report($where, $target, "nongit link");
+				next;
+			}
+			if (! -f "$basedir/$page.txt") {
+				report($where, $target, "no such source");
+				next;
+			}
+			$real_section = grab_section($page);
+			if ($real_section != $section) {
+				report($where, $target,
+					"wrong section (should be $real_section)");
+				next;
+			}
+		}
+	}
+	close $fh;
+}
+
+sub lint_it {
+	lint($File::Find::name) if -f && /\.txt$/;
+}
+
+if (!@ARGV) {
+	find({ wanted => \&lint_it, no_chdir => 1 }, $basedir);
+} else {
+	for (@ARGV) {
+		lint($_);
+	}
+}
+
+exit $found_errors;
diff --git a/Makefile b/Makefile
index bc3d41ebf3..0d59718bf7 100644
--- a/Makefile
+++ b/Makefile
@@ -2483,6 +2483,7 @@ ALL_COMMANDS += git-gui git-citool
 
 .PHONY: check-docs
 check-docs::
+	$(MAKE) -C Documentation lint-docs
 	@(for v in $(ALL_COMMANDS); \
 	do \
 		case "$$v" in \