Issue 1510 - Stop using OS.File.readTo()

lib/io.js

Index: lib/io.js
===================================================================
--- a/lib/io.js
+++ b/lib/io.js
@@ -23,17 +23,17 @@ let {Services} = Cu.import("resource://g
 let {FileUtils} = Cu.import("resource://gre/modules/FileUtils.jsm", null);
 let {OS} = Cu.import("resource://gre/modules/osfile.jsm", null);
 let {Task} = Cu.import("resource://gre/modules/Task.jsm", null);
 
 let {Prefs} = require("prefs");
 let {Utils} = require("utils");
 
 let firstRead = true;
-const BUFFER_SIZE = 0x8000;  // 32kB
+const BUFFER_SIZE = 0x80000;  // 512kB
 
 let IO = exports.IO =
 {
   /**
    * Retrieves the platform-dependent line break string.
    */
   get lineBreak()
   {
@@ -145,17 +145,16 @@ let IO = exports.IO =
           error = e;
           return;
         }
 
         callback(e);
       };
 
       let decoder = new TextDecoder();
-      let array = new Uint8Array(BUFFER_SIZE);
       Task.spawn(function()
       {
         if (firstRead && Services.vc.compare(Utils.platformVersion, "23.0a1") <= 0)
         {
           // See https://issues.adblockplus.org/ticket/530 - the first file
           // opened cannot be closed due to Gecko bug 858723. Make sure that
           // our patterns.ini file doesn't stay locked by opening a dummy file
           // first.
@@ -168,29 +167,25 @@ let IO = exports.IO =
           catch (e)
           {
             // Dummy might be locked already, we don't care
           }
         }
         firstRead = false;
 
         let f = yield OS.File.open(file.path, {read: true});
-        let numBytes;
-        do
+        while (true)
         {
-          numBytes = yield f.readTo(array);
-          if (numBytes)
-          {
-            let data = decoder.decode(numBytes == BUFFER_SIZE ?
-                                      array :
-                                      array.subarray(0, numBytes), {stream: true});
-            onProgress(data);
-          }
-        } while (numBytes);
+          let array = yield f.read(BUFFER_SIZE);
+          if (!array.length)
+            break;
 
+          let data = decoder.decode(array, {stream: true});
+          onProgress(data);
+        }
         yield f.close();
       }.bind(this)).then(onSuccess, onError);
     }
     catch (e)
     {
       callback(e);
     }
   },