Improve error messages when hitting PHP file upload issues

Summary: See T429. When you hit certain errors, you get less-than-helpful
messages like "upload error 3". Instead, produce human-readable errors.
Test Plan: Simulated errors, verified user receives decent error messages.
Reviewed By: aran
Reviewers: jungejason, tuomaspelkonen, aran, startupguy
CC: aran
Differential Revision: 816

src/applications/files/exception/upload/PhabricatorFileUploadException.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * Copyright 2011 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorFileUploadException extends Exception {
+
+  public function __construct($code) {
+    $map = array(
+      UPLOAD_ERR_INI_SIZE =>
+        "Uploaded file is too large: file is larger than the ".
+        "'upload_max_size' setting in php.ini.",
+      UPLOAD_ERR_FORM_SIZE =>
+        "File is too large.",
+      UPLOAD_ERR_PARTIAL =>
+        "File was only partially transferred, upload did not complete.",
+      UPLOAD_ERR_NO_FILE =>
+        "No file was uploaded.",
+      UPLOAD_ERR_NO_TMP_DIR =>
+        "Unable to write file: temporary directory does not exist.",
+      UPLOAD_ERR_CANT_WRITE =>
+        "Unable to write file: failed to write to temporary directory.",
+      UPLOAD_ERR_EXTENSION =>
+        "Unable to upload: a PHP extension stopped the upload.",
+    );
+
+    $message = idx($map, $code, "Upload failed: unknown error.");
+    parent::__construct($message, $code);
+  }
+}

src/applications/files/exception/upload/__init__.php

@@ -0,0 +1,12 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phutil', 'utils');
+
+
+phutil_require_source('PhabricatorFileUploadException.php');