1 #! /usr/bin/env perl
2 # SPDX-License-Identifier: GPL-2.0
3 #
4 # Detect cycles in the header file dependency graph
5 # Vegard Nossum <vegardno@ifi.uio.no>
6 #
7 
8 use strict;
9 use warnings;
10 
11 use Getopt::Long;
12 
13 my $opt_all;
14 my @opt_include;
15 my $opt_graph;
16 
17 &Getopt::Long::Configure(qw(bundling pass_through));
18 &GetOptions(
19 	help	=> \&help,
20 	version	=> \&version,
21 
22 	all	=> \$opt_all,
23 	"I=s"	=> \@opt_include,
24 	graph	=> \$opt_graph,
25 );
26 
27 push @opt_include, 'include';
28 my %deps = ();
29 my %linenos = ();
30 
31 my @headers = grep { strip($_) } @ARGV;
32 
33 parse_all(@headers);
34 
35 if($opt_graph) {
36 	graph();
37 } else {
38 	detect_cycles(@headers);
39 }
40 
41 
42 sub help {
43 	print "Usage: $0 [options] file...\n";
44 	print "\n";
45 	print "Options:\n";
46 	print "  --all\n";
47 	print "  --graph\n";
48 	print "\n";
49 	print "  -I includedir\n";
50 	print "\n";
51 	print "To make nice graphs, try:\n";
52 	print "  $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";
53 	exit;
54 }
55 
56 sub version {
57 	print "headerdep version 2\n";
58 	exit;
59 }
60 
61 # Get a file name that is relative to our include paths
62 sub strip {
63 	my $filename = shift;
64 
65 	for my $i (@opt_include) {
66 		my $stripped = $filename;
67 		$stripped =~ s/^$i\///;
68 
69 		return $stripped if $stripped ne $filename;
70 	}
71 
72 	return $filename;
73 }
74 
75 # Search for the file name in the list of include paths
76 sub search {
77 	my $filename = shift;
78 	return $filename if -f $filename;
79 
80 	for my $i (@opt_include) {
81 		my $path = "$i/$filename";
82 		return $path if -f $path;
83 	}
84 	return;
85 }
86 
87 sub 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 
113 sub 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.
142 sub 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 
164 sub mangle {
165 	$_ = shift;
166 	s/\//__/g;
167 	s/\./_/g;
168 	s/-/_/g;
169 	$_;
170 }
171 
172 # Output dependency graph in GraphViz language.
173 sub 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