From 4484946cfd29d1d3f61c03825d812601038fa75c Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Thu, 11 Mar 2021 11:48:55 -0800
Subject: [PATCH] In JSON DocumentEngine, preserve the distinction between "{}"
 and "[]"

Summary:
Ref T13635. Currently, the JSON DocumentEngine uses "phutil_json_decode()", but this can confuse "{}" and "[]".

Be more careful about how the JSON value is decoded, to preserve the distinction.

Test Plan: {F8520479}

Maniphest Tasks: T13635

Differential Revision: https://secure.phabricator.com/D21605
---
 src/__phutil_library_map__.php                 |  2 ++
 .../document/PhabricatorJSONDocumentEngine.php | 18 ++++++++++++++++++
 ...habricatorDocumentEngineParserException.php |  4 ++++
 3 files changed, 24 insertions(+)
 create mode 100644 src/applications/files/document/exception/PhabricatorDocumentEngineParserException.php

diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 065c588ddb..52e5f46bbf 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -3209,6 +3209,7 @@ phutil_register_library_map(array(
     'PhabricatorDocumentEngineBlock' => 'applications/files/diff/PhabricatorDocumentEngineBlock.php',
     'PhabricatorDocumentEngineBlockDiff' => 'applications/files/diff/PhabricatorDocumentEngineBlockDiff.php',
     'PhabricatorDocumentEngineBlocks' => 'applications/files/diff/PhabricatorDocumentEngineBlocks.php',
+    'PhabricatorDocumentEngineParserException' => 'applications/files/document/exception/PhabricatorDocumentEngineParserException.php',
     'PhabricatorDocumentRef' => 'applications/files/document/PhabricatorDocumentRef.php',
     'PhabricatorDocumentRenderingEngine' => 'applications/files/document/render/PhabricatorDocumentRenderingEngine.php',
     'PhabricatorDoorkeeperApplication' => 'applications/doorkeeper/application/PhabricatorDoorkeeperApplication.php',
@@ -9707,6 +9708,7 @@ phutil_register_library_map(array(
     'PhabricatorDocumentEngineBlock' => 'Phobject',
     'PhabricatorDocumentEngineBlockDiff' => 'Phobject',
     'PhabricatorDocumentEngineBlocks' => 'Phobject',
+    'PhabricatorDocumentEngineParserException' => 'Exception',
     'PhabricatorDocumentRef' => 'Phobject',
     'PhabricatorDocumentRenderingEngine' => 'Phobject',
     'PhabricatorDoorkeeperApplication' => 'PhabricatorApplication',
diff --git a/src/applications/files/document/PhabricatorJSONDocumentEngine.php b/src/applications/files/document/PhabricatorJSONDocumentEngine.php
index 683f1746e6..42f4469ee6 100644
--- a/src/applications/files/document/PhabricatorJSONDocumentEngine.php
+++ b/src/applications/files/document/PhabricatorJSONDocumentEngine.php
@@ -31,6 +31,17 @@ final class PhabricatorJSONDocumentEngine
     try {
       $data = phutil_json_decode($raw_data);
 
+      // See T13635. "phutil_json_decode()" always turns JSON into a PHP array,
+      // and we lose the distinction between "{}" and "[]". This distinction is
+      // important when rendering a document.
+      $data = json_decode($raw_data, false);
+      if (!$data) {
+        throw new PhabricatorDocumentEngineParserException(
+          pht(
+            'Failed to "json_decode(...)" JSON document after successfully '.
+            'decoding it with "phutil_json_decode(...).'));
+      }
+
       if (preg_match('/^\s*\[/', $raw_data)) {
         $content = id(new PhutilJSON())->encodeAsList($data);
       } else {
@@ -47,6 +58,13 @@ final class PhabricatorJSONDocumentEngine
           'This document is not valid JSON: %s',
           $ex->getMessage()));
 
+      $content = $raw_data;
+    } catch (PhabricatorDocumentEngineParserException $ex) {
+      $message = $this->newMessage(
+        pht(
+          'Unable to parse this document as JSON: %s',
+          $ex->getMessage()));
+
       $content = $raw_data;
     }
 
diff --git a/src/applications/files/document/exception/PhabricatorDocumentEngineParserException.php b/src/applications/files/document/exception/PhabricatorDocumentEngineParserException.php
new file mode 100644
index 0000000000..b664d942ad
--- /dev/null
+++ b/src/applications/files/document/exception/PhabricatorDocumentEngineParserException.php
@@ -0,0 +1,4 @@
+<?php
+
+final class PhabricatorDocumentEngineParserException
+  extends Exception {}
-- 
2.51.2