Add possibility to upload a diff file instead of using copy-paste.

Test Plan:
Go to /differential/diff/create and upload a diff file - result should be the
same as pasting the diff into the textarea.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: 1019

src/applications/differential/controller/diffcreate/DifferentialDiffCreateController.php

@@ -24,7 +24,12 @@ class DifferentialDiffCreateController extends DifferentialController {
 
     if ($request->isFormPost()) {
       $parser = new ArcanistDiffParser();
+      $diff = null;
+      try {
+        $diff = PhabricatorFile::readUploadedFileData($_FILES['diff-file']);
+      } catch (Exception $ex) {
         $diff = $request->getStr('diff');
+      }
       $changes = $parser->parseDiff($diff);
       $diff = DifferentialDiff::newFromRawChanges($changes);
 
@@ -42,17 +47,23 @@ class DifferentialDiffCreateController extends DifferentialController {
     $form = new AphrontFormView();
     $form
       ->setAction('/differential/diff/create/')
+      ->setEncType('multipart/form-data')
       ->setUser($request->getUser())
       ->appendChild(
         '<p class="aphront-form-instructions">The best way to create a '.
         'Differential diff is by using <strong>Arcanist</strong>, but you '.
         'can also just paste a diff (e.g., from <tt>svn diff</tt> or '.
-        '<tt>git diff</tt>) into this box if you really want.</p>')
+        '<tt>git diff</tt>) into this box or upload it as a file if you '.
+        'really want.</p>')
       ->appendChild(
         id(new AphrontFormTextAreaControl())
           ->setLabel('Raw Diff')
           ->setName('diff')
           ->setHeight(AphrontFormTextAreaControl::HEIGHT_VERY_TALL))
+      ->appendChild(
+        id(new AphrontFormFileControl())
+          ->setLabel('Raw Diff from file')
+          ->setName('diff-file'))
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->setValue("Create Diff \xC2\xBB"));

src/applications/differential/controller/diffcreate/__init__.php

@@ -12,7 +12,9 @@ phutil_require_module('phabricator', 'aphront/response/redirect');
 phutil_require_module('phabricator', 'applications/differential/constants/lintstatus');
 phutil_require_module('phabricator', 'applications/differential/controller/base');
 phutil_require_module('phabricator', 'applications/differential/storage/diff');
+phutil_require_module('phabricator', 'applications/files/storage/file');
 phutil_require_module('phabricator', 'view/form/base');
+phutil_require_module('phabricator', 'view/form/control/file');
 phutil_require_module('phabricator', 'view/form/control/submit');
 phutil_require_module('phabricator', 'view/form/control/textarea');
 phutil_require_module('phabricator', 'view/layout/panel');

src/applications/files/storage/file/PhabricatorFile.php

@@ -41,7 +41,7 @@ class PhabricatorFile extends PhabricatorFileDAO {
       PhabricatorPHIDConstants::PHID_TYPE_FILE);
   }
 
-  public static function newFromPHPUpload($spec, array $params = array()) {
+  public static function readUploadedFileData($spec) {
     if (!$spec) {
       throw new Exception("No file was uploaded!");
     }
@@ -64,6 +64,12 @@ class PhabricatorFile extends PhabricatorFileDAO {
       throw new Exception("File size disagrees with uploaded size.");
     }
 
+    return $file_data;
+  }
+
+  public static function newFromPHPUpload($spec, array $params = array()) {
+    $file_data = self::readUploadedFileData($spec);
+
     $file_name = nonempty(
       idx($params, 'name'),
       idx($spec,   'name'));