Issue 4023 - Move storage of subscription lists to localStorage

lib/io.js

Index: lib/io.js
===================================================================
--- a/lib/io.js
+++ b/lib/io.js
@@ -15,6 +15,8 @@
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+"use strict";
+
 const keyPrefix = "file:";
 
 function fileToKey(file)
@@ -22,33 +24,31 @@
   return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
 }
 
-function loadFile(file, successCallback, errorCallback)
+function loadFile(file)
 {
-  let key = fileToKey(file);
-
-  ext.storage.get([key], function(items)
+  return new Promise((resolve, reject) =>
   {
-    let entry = items[key];
-
-    if (entry)
-      successCallback(entry);
-    else
-      errorCallback(new Error("File doesn't exist"));
+    let key = fileToKey(file);
+    ext.storage.get([key], items =>
+    {
+      let entry = items[key];
+      if (!entry)
+      {
+        // Check in localStorage
+        try
+        {
+          entry = JSON.parse(window.localStorage.getItem(key));
+        }
+        catch(err) {}
+      }
+      if (entry)
+        resolve(entry);
+      else
+        reject(new Error("File doesn't exist"));
+    });
   });
 }
 
-function saveFile(file, data, callback)
-{
-  ext.storage.set(
-    fileToKey(file),
-    {
-      content: data,
-      lastModified: Date.now()
-    },
-    callback
-  );
-}
-
 exports.IO =
 {
   resolveFilePath: function(path)
@@ -60,47 +60,41 @@
   {
     function onLoaded(entry)
     {
-      for (let line of entry.content)
-        listener.process(line);
-
-      listener.process(null);
+      if ("content" in entry)
+      {
+        if (entry["compressed"])
+          entry.content = JSON.parse(LZString.decompressFromUTF16(entry.content));
+        for (let line of entry.content)
+          listener.process(line);
+      }
       callback(null);
     }
 
-    loadFile(file, onLoaded, callback);
+    loadFile(file).then(onLoaded, callback);
   },
 
   writeToFile: function(file, data, callback)
   {
-    saveFile(file, data, callback);
-  },
+    let entry = {};
+    let key = fileToKey(file);
 
-  copyFile: function(fromFile, toFile, callback)
-  {
-    function onLoaded(entry)
+    if (typeof browser == "undefined")
     {
-      saveFile(toFile, entry.content, callback);
+      entry[key] = {lastModified: Date.now(), content: data};
+      ext.storage.set(entry, callback);
     }
-
-    loadFile(fromFile, onLoaded, callback);
-  },
-
-  renameFile: function(fromFile, newName, callback)
-  {
-    function onLoaded()
+    else
     {
-      ext.storage.remove(fileToKey(fromFile), function()
-      {
-        ext.storage.set(keyPrefix + newName, entry, callback);
-      });
+      // Edge cannot write files larger than 1Mb (500k string in UTF-16) via 
+      // storage API. However it does not always raise an exception when trying
+      // to do so. The solution is to compress and fallback to localStorage.
+      let processedData = LZString.compressToUTF16(JSON.stringify(data));
+      ext.storage.remove(key);
+      entry[key] = {lastModified: Date.now(), content: processedData,
+                    compressed: true};
+      window.localStorage.setItem(key, JSON.stringify(entry[key]));
+      callback();
     }
-
-    loadFile(fromFile, onLoaded, callback);
-  },
-
-  removeFile: function(file, callback)
-  {
-    ext.storage.remove(fileToKey(file), callback);
   },
 
   statFile: function(file, callback)
@@ -113,6 +107,6 @@
       });
     }
 
-    loadFile(file, onLoaded, callback);
+    loadFile(file).then(onLoaded, callback);
   }
 };