scripts: add an script to parse the ABI files

Add a script to parse the Documentation/ABI files and produce
an output with all entries inside an ABI (sub)directory.

Right now, it outputs its contents on ReST format. It shouldn't
be hard to make it produce other kind of outputs, since the ABI
file parser is implemented in separate than the output generator.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scripts/get_abi.pl

+#!/usr/bin/perl
+
+use strict;
+use Pod::Usage;
+use Getopt::Long;
+use File::Find;
+use Fcntl ':mode';
+
+my $help;
+my $man;
+my $debug;
+
+GetOptions(
+	"debug|d+" => \$debug,
+	'help|?' => \$help,
+	man => \$man
+) or pod2usage(2);
+
+pod2usage(1) if $help;
+pod2usage(-exitstatus => 0, -verbose => 2) if $man;
+
+pod2usage(2) if (scalar @ARGV != 1);
+
+my ($prefix) = @ARGV;
+
+require Data::Dumper if ($debug);
+
+my %data;
+
+#
+# Displays an error message, printing file name and line
+#
+sub parse_error($$$$) {
+	my ($file, $ln, $msg, $data) = @_;
+
+	print STDERR "file $file#$ln: $msg at\n\t$data";
+}
+
+#
+# Parse an ABI file, storing its contents at %data
+#
+sub parse_abi {
+	my $file = $File::Find::name;
+
+	my $mode = (stat($file))[2];
+	return if ($mode & S_IFDIR);
+	return if ($file =~ m,/README,);
+
+	my $name = $file;
+	$name =~ s,.*/,,;
+
+	my $type = $file;
+	$type =~ s,.*/(.*)/.*,$1,;
+
+	my $what;
+	my $new_what;
+	my $tag;
+	my $ln;
+
+	print STDERR "Opening $file\n" if ($debug > 1);
+	open IN, $file;
+	while(<IN>) {
+		$ln++;
+		if (m/^(\S+):\s*(.*)/i) {
+			my $new_tag = lc($1);
+			my $content = $2;
+
+			if (!($new_tag =~ m/(what|date|kernelversion|contact|description|users)/)) {
+				if ($tag eq "description") {
+					$data{$what}->{$tag} .= "\n$content";;
+					$data{$what}->{$tag} =~ s/\n+$//;
+					next;
+				} else {
+					parse_error($file, $ln, "tag '$tag' is invalid", $_);
+				}
+			}
+
+			if ($new_tag =~ m/what/) {
+				if ($tag =~ m/what/) {
+					$what .= ", " . $content;
+				} else {
+					$what = $content;
+					$new_what = 1;
+				}
+				$tag = $new_tag;
+				next;
+			}
+
+			$tag = $new_tag;
+
+			if ($new_what) {
+				$new_what = 0;
+
+				$data{$what}->{type} = $type;
+				$data{$what}->{file} = $name;
+				print STDERR "\twhat: $what\n" if ($debug > 1);
+			}
+
+			if (!$what) {
+				parse_error($file, $ln, "'What:' should come first:", $_);
+				next;
+			}
+			$data{$what}->{$tag} = $content;
+			next;
+		}
+
+		# Silently ignore any headers before the database
+		next if (!$tag);
+
+		if (m/^\s*(.*)/) {
+			$data{$what}->{$tag} .= "\n$1";
+			$data{$what}->{$tag} =~ s/\n+$//;
+			next;
+		}
+
+		# Everything else is error
+		parse_error($file, $ln, "Unexpected line:", $_);
+	}
+	close IN;
+}
+
+# Outputs the output on ReST format
+sub output_rest {
+	foreach my $what (sort keys %data) {
+		my $type = $data{$what}->{type};
+		my $file = $data{$what}->{file};
+
+		my $w = $what;
+		$w =~ s/([\(\)\_\-\*\=\^\~\\])/\\$1/g;
+
+		print "$w\n\n";
+		print "- defined on file $file (type: $type)\n\n::\n\n";
+
+		my $desc = $data{$what}->{description};
+		$desc =~ s/^\s+//;
+
+		# Remove title markups from the description, as they won't work
+		$desc =~ s/\n[\-\*\=\^\~]+\n/\n/g;
+
+		# put everything inside a code block
+		$desc =~ s/\n/\n /g;
+
+
+		if (!($desc =~ /^\s*$/)) {
+			print " $desc\n\n";
+		} else {
+			print " DESCRIPTION MISSING\n\n";
+		}
+	}
+}
+
+#
+# Parses all ABI files located at $prefix dir
+#
+find({wanted =>\&parse_abi, no_chdir => 1}, $prefix);
+
+print STDERR Data::Dumper->Dump([\%data], [qw(*data)]) if ($debug);
+
+#
+# Outputs an ReST file with the ABI contents
+#
+output_rest
+
+
+__END__
+
+=head1 NAME
+
+abi_book.pl - parse the Linux ABI files and produce a ReST book.
+
+=head1 SYNOPSIS
+
+B<abi_book.pl> [--debug] <ABI_DIR>]
+
+=head1 OPTIONS
+
+=over 8
+
+=item B<--debug>
+
+Put the script in verbose mode, useful for debugging. Can be called multiple
+times, to increase verbosity.
+
+=item B<--help>
+
+Prints a brief help message and exits.
+
+=item B<--man>
+
+Prints the manual page and exits.
+
+=back
+
+=head1 DESCRIPTION
+
+Parse the Linux ABI files from ABI DIR (usually located at Documentation/ABI)
+and produce a ReST book containing the Linux ABI.
+
+=head1 BUGS
+
+Report bugs to Mauro Carvalho Chehab <mchehab@s-opensource.com>
+
+=head1 COPYRIGHT
+
+Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab@s-opensource.com>.
+
+License GPLv2: GNU GPL version 2 <http://gnu.org/licenses/gpl.html>.
+
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+
+=cut