linux/scripts/headerdep.pl
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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 $opt_graph;
  15
  16&Getopt::Long::Configure(qw(bundling pass_through));
  17&GetOptions(
  18        help    => \&help,
  19        version => \&version,
  20
  21        all     => \$opt_all,
  22        "I=s"   => \@opt_include,
  23        graph   => \$opt_graph,
  24);
  25
  26push @opt_include, 'include';
  27my %deps = ();
  28my %linenos = ();
  29
  30my @headers = grep { strip($_) } @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        return;
  84}
  85
  86sub parse_all {
  87        # Parse all the headers.
  88        my @queue = @_;
  89        while(@queue) {
  90                my $header = pop @queue;
  91                next if exists $deps{$header};
  92
  93                $deps{$header} = [] unless exists $deps{$header};
  94
  95                my $path = search($header);
  96                next unless $path;
  97
  98                open(my $file, '<', $path) or die($!);
  99                chomp(my @lines = <$file>);
 100                close($file);
 101
 102                for my $i (0 .. $#lines) {
 103                        my $line = $lines[$i];
 104                        if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {
 105                                push @queue, $dep;
 106                                push @{$deps{$header}}, [$i + 1, $dep];
 107                        }
 108                }
 109        }
 110}
 111
 112sub print_cycle {
 113        # $cycle[n] includes $cycle[n + 1];
 114        # $cycle[-1] will be the culprit
 115        my $cycle = shift;
 116
 117        # Adjust the line numbers
 118        for my $i (0 .. $#$cycle - 1) {
 119                $cycle->[$i]->[0] = $cycle->[$i + 1]->[0];
 120        }
 121        $cycle->[-1]->[0] = 0;
 122
 123        my $first = shift @$cycle;
 124        my $last = pop @$cycle;
 125
 126        my $msg = "In file included";
 127        printf "%s from %s,\n", $msg, $last->[1] if defined $last;
 128
 129        for my $header (reverse @$cycle) {
 130                printf "%s from %s:%d%s\n",
 131                        " " x length $msg,
 132                        $header->[1], $header->[0],
 133                        $header->[1] eq $last->[1] ? ' <-- here' : '';
 134        }
 135
 136        printf "%s:%d: warning: recursive header inclusion\n",
 137                $first->[1], $first->[0];
 138}
 139
 140# Find and print the smallest cycle starting in the specified node.
 141sub detect_cycles {
 142        my @queue = map { [[0, $_]] } @_;
 143        while(@queue) {
 144                my $top = pop @queue;
 145                my $name = $top->[-1]->[1];
 146
 147                for my $dep (@{$deps{$name}}) {
 148                        my $chain = [@$top, [$dep->[0], $dep->[1]]];
 149
 150                        # If the dep already exists in the chain, we have a
 151                        # cycle...
 152                        if(grep { $_->[1] eq $dep->[1] } @$top) {
 153                                print_cycle($chain);
 154                                next if $opt_all;
 155                                return;
 156                        }
 157
 158                        push @queue, $chain;
 159                }
 160        }
 161}
 162
 163sub mangle {
 164        $_ = shift;
 165        s/\//__/g;
 166        s/\./_/g;
 167        s/-/_/g;
 168        $_;
 169}
 170
 171# Output dependency graph in GraphViz language.
 172sub graph {
 173        print "digraph {\n";
 174
 175        print "\t/* vertices */\n";
 176        for my $header (keys %deps) {
 177                printf "\t%s [label=\"%s\"];\n",
 178                        mangle($header), $header;
 179        }
 180
 181        print "\n";
 182
 183        print "\t/* edges */\n";
 184        for my $header (keys %deps) {
 185                for my $dep (@{$deps{$header}}) {
 186                        printf "\t%s -> %s;\n",
 187                                mangle($header), mangle($dep->[1]);
 188                }
 189        }
 190
 191        print "}\n";
 192}
 193
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