[PATCH] headerdep: a tool for detecting inclusion cycles in header files

[Vegard Nossum]

Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
 Makefile             |    5 ++
 scripts/headerdep.pl |  143 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 148 insertions(+), 0 deletions(-)
 create mode 100755 scripts/headerdep.pl

diff --git a/Makefile b/Makefile
index 39516bf..488b193 100644
--- a/Makefile
+++ b/Makefile
@@ -1021,6 +1021,10 @@ PHONY += headers_check
 headers_check: headers_install
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.headersinst ARCH=$(SRCARCH) obj=include HDRCHECK=1
 
+PHONY += headerdep
+headerdep:
+	$(Q)$(MAKE) C=2 CHECK=scripts/headerdep.pl
+
 # ---------------------------------------------------------------------------
 # Modules
 
@@ -1210,6 +1214,7 @@ help:
 	@if [ -r $(srctree)/include/asm-$(SRCARCH)/Kbuild ]; then \
 	 echo  '  headers_check   - Sanity check on exported headers'; \
 	 fi
+	@echo  '  headerdep       - Detect inclusion cycles in headers'
 	@echo  ''
 	@echo  'Kernel packaging:'
 	@$(MAKE) $(build)=$(package-dir) help
diff --git a/scripts/headerdep.pl b/scripts/headerdep.pl
new file mode 100755
index 0000000..c993d16
--- /dev/null
+++ b/scripts/headerdep.pl
@@ -0,0 +1,143 @@
+#! /usr/bin/perl
+#
+# Detect cycles in the header file dependency graph
+# Vegard Nossum <vegardno@xxxxxxxxxx>
+#
+
+use strict;
+use warnings;
+
+my @I = ('include');
+my %deps = ();
+
+my @headers = grep { strip($_) } @ARGV;
+
+parse_all(@headers);
+
+detect_cycles(@headers);
+#graph();
+exit;
+
+
+# Get a file name that is relative to our include paths
+sub strip {
+	my $filename = shift;
+
+	for my $i (@I) {
+		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 (@I) {
+		my $path = sprintf "%s/%s", $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 $line (@lines) {
+			if(my($dep) = ($line =~ m/^#\s*include <([^>]+)>/)) {
+				push @queue, $dep;
+				push @{$deps{$header}}, $dep;
+			}
+		}
+	}
+}
+
+sub print_cycle {
+	my $cycle = shift;
+
+	my $first = shift @$cycle;
+	my $last = pop @$cycle;
+
+	my $msg = "In file included";
+	printf "%s from %s,\n", $msg, $last if defined $last;
+
+	for my $header (reverse @$cycle) {
+		printf "%*.s from %s\n", length $msg, '', $header;
+	}
+
+	printf "%s: warning: recursive header inclusion\n", $first;
+}
+
+# Find and print the smallest cycle starting in the specified node.
+sub detect_cycles {
+	my @queue = map { [$_] } @_;
+	while(@queue) {
+		my $top = pop @queue;
+		my $name = $top->[-1];
+
+		for my $dep (@{$deps{$name}}) {
+			my $chain = [@$top, $dep];
+
+			if(grep { $_ eq $dep } @$top) {
+				print_cycle($chain);
+				return;
+			}
+
+			push @queue, $chain;
+		}
+	}
+}
+
+sub mangle {
+	$_ = shift;
+	s/\//__/g;
+	s/\./_/g;
+	s/-/_/g;
+	$_;
+}
+
+sub escape {
+	$_ = shift;
+}
+
+# Output dependency graph in GraphViz language.
+sub graph {
+	printf "digraph {\n";
+
+	printf "\t/* vertices */\n";
+	for my $header (keys %deps) {
+		printf "\t%s [label=\"%s\"];\n",
+			mangle($header), escape($header);
+	}
+
+	printf "\n";
+
+	printf "\t/* edges */\n";
+	for my $header (keys %deps) {
+		for my $dep (@{$deps{$header}}) {
+			printf "\t%s -> %s;\n",
+				mangle($header), mangle($dep);
+		}
+	}
+
+	printf "}\n";
+}
-- 
1.5.4.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/