Fixed: writing patterns.ini might leave left-overs from previous content

lib/adblockplus_compat.js

Index: lib/adblockplus_compat.js
===================================================================
--- a/lib/adblockplus_compat.js
+++ b/lib/adblockplus_compat.js
@@ -174,39 +174,49 @@ require.scopes.io =
     {
       this._getFileEntry(file, true, function(fs, fileEntry)
       {
         fileEntry.createWriter(function(writer)
         {
           writer.onwriteend = function()
           {
             if (writer.error)
+            {
               callback(writer.error);
-            else
-              callback(null);
-          };
+              return;
+            }
 
-          var blob;
-          try
-          {
-            blob = new Blob([data.join("\n") + "\n"], {type: "text/plain"});
-          }
-          catch (e)
-          {
-            if (!(e instanceof TypeError))
-              throw e;
+            writer.onwriteend = function()
+            {
+              if (writer.error)
+                callback(writer.error);
+              else
+                callback(null);
+            }.bind(this);
 
-            // Blob wasn't a constructor before Chrome 20
-            var builder = new (window.BlobBuilder || window.WebKitBlobBuilder);
-            builder.append(data.join("\n") + "\n");
-            blob = builder.getBlob("text/plain");
-          }
-          writer.write(blob);
-        }, callback);
-      }, callback);
+            var blob;
+            try
+            {
+              blob = new Blob([data.join(this.lineBreak) + this.lineBreak], {type: "text/plain"});
+            }
+            catch (e)
+            {
+              if (!(e instanceof TypeError))
+                throw e;
+
+              // Blob wasn't a constructor before Chrome 20
+              var builder = new (window.BlobBuilder || window.WebKitBlobBuilder);
+              builder.append(data.join(this.lineBreak) + this.lineBreak);
+              blob = builder.getBlob("text/plain");
+            }
+            writer.write(blob);
+          }.bind(this);
+          writer.truncate(0);
+        }.bind(this), callback);
+      }.bind(this), callback);
     },
 
     copyFile: function(fromFile, toFile, callback)
     {
       // Simply combine read and write operations
       var data = [];
       this.readFromFile(fromFile, false, {
         process: function(line)