Ensure that unzipped folder does not exist before unzip on Windows (#732)

* Ensure that Unzipped folder does not exists before unzip

* Updated comment

* Renamed InitUnzippedFolderAsync -> CreateUnzippedFolderAsync, getFolder -> existingFolder

Author: ymusiychuk-lohika

windows/CodePush.Net46/UpdateManager.cs

@@ -45,11 +45,10 @@ internal async Task DownloadPackageAsync(JObject updatePackage, string expectedB
             try
             {
                 // Unzip the downloaded file and then delete the zip
-                var unzippedFolder = await GetUnzippedFolderAsync().ConfigureAwait(false);
+                var unzippedFolder = await CreateUnzippedFolderAsync().ConfigureAwait(false);
                 /**
                  * TODO:
                  *  1) ZipFile.ExtractToDirectory is not reliable and throws exception if:
-                 *      - folder exists already
                  *      - path is too long (> 250 chars)
                  *
                  *  2) Un-zipping is quite long operation. Does it make sense for async?
@@ -292,9 +291,16 @@ private async Task<IFile> GetStatusFileAsync()
             return await codePushFolder.CreateFileAsync(CodePushConstants.StatusFileName, CreationCollisionOption.OpenIfExists).ConfigureAwait(false);
         }
 
-        private async Task<IFolder> GetUnzippedFolderAsync()
+        private async Task<IFolder> CreateUnzippedFolderAsync()
         {
             var codePushFolder = await UpdateUtils.GetCodePushFolderAsync().ConfigureAwait(false);
+            var isUnzippedFolderExists = await codePushFolder.CheckExistsAsync(CodePushConstants.UnzippedFolderName).ConfigureAwait(false);
+
+            if (isUnzippedFolderExists != ExistenceCheckResult.NotFound)
+            {
+                await codePushFolder.GetFolderAsync(CodePushConstants.UnzippedFolderName).ContinueWith((existingFolder) => existingFolder.Result.DeleteAsync());
+            }
+
             return await codePushFolder.CreateFolderAsync(CodePushConstants.UnzippedFolderName, CreationCollisionOption.OpenIfExists).ConfigureAwait(false);
         }
 

windows/CodePush/UpdateManager.cs

@@ -53,7 +53,7 @@ internal async Task DownloadPackageAsync(JObject updatePackage, string expectedB
             try
             {
                 // Unzip the downloaded file and then delete the zip
-                StorageFolder unzippedFolder = await GetUnzippedFolderAsync().ConfigureAwait(false);
+                StorageFolder unzippedFolder = await CreateUnzippedFolderAsync().ConfigureAwait(false);
                 ZipFile.ExtractToDirectory(downloadFile.Path, unzippedFolder.Path);
                 await downloadFile.DeleteAsync().AsTask().ConfigureAwait(false);
 
@@ -99,7 +99,6 @@ internal async Task DownloadPackageAsync(JObject updatePackage, string expectedB
                 await downloadFile.MoveAsync(newUpdateFolder).AsTask().ConfigureAwait(false);
             }
             /*TODO: ZipFile.ExtractToDirectory is not reliable and throws exceptions if:
-            - folder exists already
             - path is too long
             it needs to be handled
             */
@@ -278,9 +277,16 @@ private async Task<StorageFile> GetStatusFileAsync()
             return await codePushFolder.CreateFileAsync(CodePushConstants.StatusFileName, CreationCollisionOption.OpenIfExists).AsTask().ConfigureAwait(false);
         }
 
-        private async Task<StorageFolder> GetUnzippedFolderAsync()
+        private async Task<StorageFolder> CreateUnzippedFolderAsync()
         {
             StorageFolder codePushFolder = await GetCodePushFolderAsync().ConfigureAwait(false);
+            var unzippedFolder = await codePushFolder.TryGetItemAsync(CodePushConstants.UnzippedFolderName).AsTask().ConfigureAwait(false);
+
+            if (unzippedFolder != null)
+            {
+                await unzippedFolder.DeleteAsync();
+            }
+
             return await codePushFolder.CreateFolderAsync(CodePushConstants.UnzippedFolderName, CreationCollisionOption.OpenIfExists).AsTask().ConfigureAwait(false);
         }