--- trunk/mkinitrd-magellan/isolinux/checksumiso.pl	2010/08/19 08:27:19	1132
+++ trunk/mkinitrd-magellan/isolinux/checksumiso.pl	2010/08/19 09:50:43	1133
@@ -9,11 +9,25 @@
 
 ($file) = @ARGV;
 
-open(FILE, '+<', $file) or die "$0: Cannot open $file: $!\n";
+open(FILE, '+<', $file) or die "$0: cannot open $file: $!\n";
 binmode FILE;
 
+@fstat = stat(FILE) or die "$0: stat $file: $!\n";
+if (!$fstat[7]) {
+    die "$0: $file: cannot query length\n";
+}
+
+# Pad file to a multiple of 2048 bytes
+$frac = $fstat[7] % 2048;
+if ($frac) {
+    seek(FILE,$fstat[7],0)
+	or die "$0: $file: cannot seek to end\n";
+    print FILE "\0" x (2048-$frac);
+}
+
+# Checksum the file post header
 if ( !seek(FILE,64,0) ) {
-    die "$0: Cannot seek past header\n";
+    die "$0: $file: cannot seek past header\n";
 }
 
 $csum  = 0;
@@ -25,8 +39,9 @@
     $bytes += $n;
 }
 
+# Update header
 if ( !seek(FILE,16,0) ) {
-    die "$0: Cannot seek to header\n";
+    die "$0: $file: cannot seek to header\n";
 }
 
 print FILE pack("VV", $bytes, $csum);