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1#! /usr/bin/perl
2#
3# Detect cycles in the header file dependency graph
4# Vegard Nossum <vegardno@ifi.uio.no>
5#
6
7use strict;
8use warnings;
9
10use Getopt::Long;
11
12my $opt_all;
13my @opt_include;
14my $opt_graph;
15
16&Getopt::Long::Configure(qw(bundling pass_through));
17&GetOptions(
18	help	=> \&help,
19	version	=> \&version,
20
21	all	=> \$opt_all,
22	I	=> \@opt_include,
23	graph	=> \$opt_graph,
24);
25
26push @opt_include, 'include';
27my %deps = ();
28my %linenos = ();
29
30my @headers = grep { strip($_) } @ARGV;
31
32parse_all(@headers);
33
34if($opt_graph) {
35	graph();
36} else {
37	detect_cycles(@headers);
38}
39
40
41sub help {
42	print "Usage: $0 [options] file...\n";
43	print "\n";
44	print "Options:\n";
45	print "  --all\n";
46	print "  --graph\n";
47	print "\n";
48	print "  -I includedir\n";
49	print "\n";
50	print "To make nice graphs, try:\n";
51	print "  $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";
52	exit;
53}
54
55sub version {
56	print "headerdep version 2\n";
57	exit;
58}
59
60# Get a file name that is relative to our include paths
61sub strip {
62	my $filename = shift;
63
64	for my $i (@opt_include) {
65		my $stripped = $filename;
66		$stripped =~ s/^$i\///;
67
68		return $stripped if $stripped ne $filename;
69	}
70
71	return $filename;
72}
73
74# Search for the file name in the list of include paths
75sub search {
76	my $filename = shift;
77	return $filename if -f $filename;
78
79	for my $i (@opt_include) {
80		my $path = "$i/$filename";
81		return $path if -f $path;
82	}
83
84	return undef;
85}
86
87sub parse_all {
88	# Parse all the headers.
89	my @queue = @_;
90	while(@queue) {
91		my $header = pop @queue;
92		next if exists $deps{$header};
93
94		$deps{$header} = [] unless exists $deps{$header};
95
96		my $path = search($header);
97		next unless $path;
98
99		open(my $file, '<', $path) or die($!);
100		chomp(my @lines = <$file>);
101		close($file);
102
103		for my $i (0 .. $#lines) {
104			my $line = $lines[$i];
105			if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {
106				push @queue, $dep;
107				push @{$deps{$header}}, [$i + 1, $dep];
108			}
109		}
110	}
111}
112
113sub print_cycle {
114	# $cycle[n] includes $cycle[n + 1];
115	# $cycle[-1] will be the culprit
116	my $cycle = shift;
117
118	# Adjust the line numbers
119	for my $i (0 .. $#$cycle - 1) {
120		$cycle->[$i]->[0] = $cycle->[$i + 1]->[0];
121	}
122	$cycle->[-1]->[0] = 0;
123
124	my $first = shift @$cycle;
125	my $last = pop @$cycle;
126
127	my $msg = "In file included";
128	printf "%s from %s,\n", $msg, $last->[1] if defined $last;
129
130	for my $header (reverse @$cycle) {
131		printf "%s from %s:%d%s\n",
132			" " x length $msg,
133			$header->[1], $header->[0],
134			$header->[1] eq $last->[1] ? ' <-- here' : '';
135	}
136
137	printf "%s:%d: warning: recursive header inclusion\n",
138		$first->[1], $first->[0];
139}
140
141# Find and print the smallest cycle starting in the specified node.
142sub detect_cycles {
143	my @queue = map { [[0, $_]] } @_;
144	while(@queue) {
145		my $top = pop @queue;
146		my $name = $top->[-1]->[1];
147
148		for my $dep (@{$deps{$name}}) {
149			my $chain = [@$top, [$dep->[0], $dep->[1]]];
150
151			# If the dep already exists in the chain, we have a
152			# cycle...
153			if(grep { $_->[1] eq $dep->[1] } @$top) {
154				print_cycle($chain);
155				next if $opt_all;
156				return;
157			}
158
159			push @queue, $chain;
160		}
161	}
162}
163
164sub mangle {
165	$_ = shift;
166	s/\//__/g;
167	s/\./_/g;
168	s/-/_/g;
169	$_;
170}
171
172# Output dependency graph in GraphViz language.
173sub graph {
174	print "digraph {\n";
175
176	print "\t/* vertices */\n";
177	for my $header (keys %deps) {
178		printf "\t%s [label=\"%s\"];\n",
179			mangle($header), $header;
180	}
181
182	print "\n";
183
184	print "\t/* edges */\n";
185	for my $header (keys %deps) {
186		for my $dep (@{$deps{$header}}) {
187			printf "\t%s -> %s;\n",
188				mangle($header), mangle($dep->[1]);
189		}
190	}
191
192	print "}\n";
193}
194