fix: better detection for JSON with XSSI protection prefix

https://security.stackexchange.com/q/110539

Signed-off-by: Jack Cherng <[email protected]>

plugin/commands/auto_set_syntax.py

@@ -252,11 +252,17 @@ def is_large_file(view: sublime.View) -> bool:
         return view.size() >= 10 * 1024  # 10KB
 
     def is_json(view: sublime.View) -> bool:
-        view_size = view.size()
-        text_begin = re.sub(r"\s+", "", view.substr(sublime.Region(0, 10)))
-        text_end = re.sub(r"\s+", "", view.substr(sublime.Region(view_size - 10, view_size)))
+        view_snapshot = G.view_snapshot_collection.get_by_view(view)
+        assert view_snapshot
 
-        return bool(
+        text_begin = re.sub(r"\s+", "", view_snapshot.content[:10])
+        text_end = re.sub(r"\s+", "", view_snapshot.content[-10:])
+
+        # XSSI protection prefix (https://security.stackexchange.com/q/110539)
+        if text_begin.startswith((")]}'\n", ")]}',\n")):
+            return True
+
+        return is_large_file(view) and bool(
             # map
             (re.search(r'^\{"', text_begin) and re.search(r'(?:[\d"\]}]|true|false|null)\}$', text_end))
             # array
@@ -265,9 +271,8 @@ def is_json(view: sublime.View) -> bool:
             or (text_begin.startswith("[{") and text_end.endswith("}]"))
         )
 
-    if is_large_file(view):
-        if is_json(view) and (syntax := find_syntax_by_syntax_like("scope:source.json")):
-            return assign_syntax_to_view(view, syntax, details={"event": event, "reason": "heuristics"})
+    if is_json(view) and (syntax := find_syntax_by_syntax_like("scope:source.json")):
+        return assign_syntax_to_view(view, syntax, details={"event": event, "reason": "heuristics"})
 
     return False
 

plugin/snapshot.py

@@ -12,7 +12,7 @@
 
 from .constants import VIEW_RUN_ID_SETTINGS_KEY
 from .settings import get_merged_plugin_setting
-from .utils import head_tail_content_st, remove_prefix
+from .utils import get_view_by_id, head_tail_content_st, remove_prefix
 
 
 @dataclass
@@ -52,6 +52,10 @@ def file_size(self) -> int:
         """The file size in bytes, -1 if file not on a disk."""
         return self.path_obj.stat().st_size if self.path_obj else -1
 
+    @property
+    def view(self) -> sublime.View | None:
+        return get_view_by_id(self.id)
+
 
 # `UserDict` is not subscriptable until Python 3.9...
 if TYPE_CHECKING: