kbuild: add headerdep used to detect inclusion cycles in header files

include/linux/utsrelease.h: include/config/kernel.release FORCE

	$(call filechk,utsrelease.h)

PHONY += headerdep

headerdep:

	$(Q)find include/ -name '*.h' | xargs --max-args 1 scripts/headerdep.pl

# ---------------------------------------------------------------------------

PHONY += depend dep

	@echo  '  versioncheck    - Sanity check on version.h usage'

	@echo  '  includecheck    - Check for duplicate included header files'

	@echo  '  export_report   - List the usages of all exported symbols'

	@echo  '  headers_check   - Sanity check on exported headers'; \

	@echo  '  headers_check   - Sanity check on exported headers'

	@echo  '  headerdep       - Detect inclusion cycles in headers'; \

	 echo  ''

	@echo  'Kernel packaging:'

	@$(MAKE) $(build)=$(package-dir) help

#! /usr/bin/perl

#

# Detect cycles in the header file dependency graph

# Vegard Nossum <vegardno@ifi.uio.no>

#

use strict;

use warnings;

use Getopt::Long;

my $opt_all;

my @opt_include;

my $opt_graph;

&Getopt::Long::Configure(qw(bundling pass_through));

&GetOptions(

	help	=> \&help,

	version	=> \&version,

	all	=> \$opt_all,

	I	=> \@opt_include,

	graph	=> \$opt_graph,

);

push @opt_include, 'include';

my %deps = ();

my %linenos = ();

my @headers = grep { strip($_) } @ARGV;

parse_all(@headers);

if($opt_graph) {

	graph();

} else {

	detect_cycles(@headers);

}

sub help {

	print "Usage: $0 [options] file...\n";

	print "\n";

	print "Options:\n";

	print "  --all\n";

	print "  --graph\n";

	print "\n";

	print "  -I includedir\n";

	print "\n";

	print "To make nice graphs, try:\n";

	print "  $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";

	exit;

}

sub version {

	print "headerdep version 2\n";

	exit;

}

# Get a file name that is relative to our include paths

sub strip {

	my $filename = shift;

	for my $i (@opt_include) {

		my $stripped = $filename;

		$stripped =~ s/^$i\///;

		return $stripped if $stripped ne $filename;

	}

	return $filename;

}

# Search for the file name in the list of include paths

sub search {

	my $filename = shift;

	return $filename if -f $filename;

	for my $i (@opt_include) {

		my $path = "$i/$filename";

		return $path if -f $path;

	}

	return undef;

}

sub parse_all {

	# Parse all the headers.

	my @queue = @_;

	while(@queue) {

		my $header = pop @queue;

		next if exists $deps{$header};

		$deps{$header} = [] unless exists $deps{$header};

		my $path = search($header);

		next unless $path;

		open(my $file, '<', $path) or die($!);

		chomp(my @lines = <$file>);

		close($file);

		for my $i (0 .. $#lines) {

			my $line = $lines[$i];

			if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {

				push @queue, $dep;

				push @{$deps{$header}}, [$i + 1, $dep];

			}

		}

	}

}

sub print_cycle {

	# $cycle[n] includes $cycle[n + 1];

	# $cycle[-1] will be the culprit

	my $cycle = shift;

	# Adjust the line numbers

	for my $i (0 .. $#$cycle - 1) {

		$cycle->[$i]->[0] = $cycle->[$i + 1]->[0];

	}

	$cycle->[-1]->[0] = 0;

	my $first = shift @$cycle;

	my $last = pop @$cycle;

	my $msg = "In file included";

	printf "%s from %s,\n", $msg, $last->[1] if defined $last;

	for my $header (reverse @$cycle) {

		printf "%s from %s:%d%s\n",

			" " x length $msg,

			$header->[1], $header->[0],

			$header->[1] eq $last->[1] ? ' <-- here' : '';

	}

	printf "%s:%d: warning: recursive header inclusion\n",

		$first->[1], $first->[0];

}

# Find and print the smallest cycle starting in the specified node.

sub detect_cycles {

	my @queue = map { [[0, $_]] } @_;

	while(@queue) {

		my $top = pop @queue;

		my $name = $top->[-1]->[1];

		for my $dep (@{$deps{$name}}) {

			my $chain = [@$top, [$dep->[0], $dep->[1]]];

			# If the dep already exists in the chain, we have a

			# cycle...

			if(grep { $_->[1] eq $dep->[1] } @$top) {

				print_cycle($chain);

				next if $opt_all;

				return;

			}

			push @queue, $chain;

		}

	}

}

sub mangle {

	$_ = shift;

	s/\//__/g;

	s/\./_/g;

	s/-/_/g;

	$_;

}

# Output dependency graph in GraphViz language.

sub graph {

	print "digraph {\n";

	print "\t/* vertices */\n";

	for my $header (keys %deps) {

		printf "\t%s [label=\"%s\"];\n",

			mangle($header), $header;

	}

	print "\n";

	print "\t/* edges */\n";

	for my $header (keys %deps) {

		for my $dep (@{$deps{$header}}) {

			printf "\t%s -> %s;\n",

				mangle($header), mangle($dep->[1]);

		}

	}

	print "}\n";

}