sensors-detect: Use modules.builtin instead of /sys/module

/sys/module doesn't actually contain all built-in modules, only the
ones which have a version or at least one parameter. Better use file
modules.builtin which is generated since kernel 2.6.33, it is complete
and this will let us handle built-in modules properly.

CHANGES

@@ -4,6 +4,7 @@ lm-sensors CHANGES file
 SVN HEAD
   init: Fix EnvironmentFile in service files
   sensors-detect: Report built-in drivers as such
+                  Use modules.builtin instead of /sys/module
 
 3.3.4 (2013-05-27)
   sensors.conf.5: Mention "sensors -u" to get the raw feature names

prog/detect/sensors-detect

@@ -2616,11 +2616,12 @@ sub initialize_conf
 # [2] -> SUBLEVEL
 # [3] -> EXTRAVERSION
 #
-use vars qw(@kernel_version $kernel_arch);
+use vars qw($kernel_version @kernel_version $kernel_arch);
 
 sub initialize_kernel_version
 {
-	`uname -r` =~ /(\d+)\.(\d+)\.(\d+)(.*)/;
+	chomp($kernel_version = `uname -r`);
+	$kernel_version =~ /(\d+)\.(\d+)\.(\d+)(.*)/;
 	@kernel_version = ($1, $2, $3, $4);
 	chomp($kernel_arch = `uname -m`);
 
@@ -2792,20 +2793,19 @@ use vars qw(%modules_list %modules_supported @modules_we_loaded);
 
 sub initialize_modules_list
 {
-	local $_;
+	local ($_, *INPUTFILE);
 
-	# /sys/module contains built-in drivers too, but doesn't exist on
-	# older kernels (added in kernel 2.6.7)
-	if (opendir(local *MODULES, "$sysfs_root/module")) {
-		while (defined($_ = readdir(MODULES))) {
-			next if m/^\./;
-			$modules_list{$1} = 1 if m/^(\S*)/;
+	# Starting with kernel 2.6.33, a list of built-in modules is available
+	if (open(*INPUTFILE, "/lib/modules/$kernel_version/modules.builtin")) {
+		while (<INPUTFILE>) {
+			tr/-/_/;
+			$modules_list{$1} = 1 if m/\/([^\/]+)\.ko$/;
 		}
-		return;
+		close(INPUTFILE);
 	}
 
-	# Fall back to /proc/modules as it is always available
-	open(local *INPUTFILE, "/proc/modules") or return;
+	# List all loaded modules
+	open(*INPUTFILE, "/proc/modules") or return;
 	while (<INPUTFILE>) {
 		$modules_list{$1} = 1 if m/^(\S*)/;
 	}