[Downloader] Add schema validation to info.json file processing (#3533)

* schema v1

* set hidden to True for shared libs

* fix test data

* add warning about invalid top-level structure

* don't show full traceback for JSONDecodeError

redbot/cogs/downloader/json_mixins.py

@@ -1,6 +1,9 @@
 import json
 from pathlib import Path
-from typing import Optional, Tuple, Dict, Any
+from typing import Any, Dict, Tuple
+
+from .info_schemas import REPO_SCHEMA, update_mixin
+from .log import log
 
 
 class RepoJSONMixin:
@@ -9,35 +12,36 @@ class RepoJSONMixin:
     def __init__(self, repo_folder: Path):
         self._repo_folder = repo_folder
 
-        self.author: Tuple[str, ...] = ()
-        self.install_msg: Optional[str] = None
-        self.short: Optional[str] = None
-        self.description: Optional[str] = None
+        self.author: Tuple[str, ...]
+        self.install_msg: str
+        self.short: str
+        self.description: str
 
         self._info_file = repo_folder / self.INFO_FILE_NAME
-        if self._info_file.exists():
-            self._read_info_file()
+        self._info: Dict[str, Any]
 
-        self._info: Dict[str, Any] = {}
+        self._read_info_file()
 
     def _read_info_file(self) -> None:
-        if not (self._info_file.exists() or self._info_file.is_file()):
-            return
-
-        try:
-            with self._info_file.open(encoding="utf-8") as f:
-                info = json.load(f)
-        except json.JSONDecodeError:
-            return
+        if self._info_file.exists():
+            try:
+                with self._info_file.open(encoding="utf-8") as f:
+                    info = json.load(f)
+            except json.JSONDecodeError as e:
+                log.error(
+                    "Invalid JSON information file at path: %s\nError: %s", self._info_file, str(e)
+                )
+                info = {}
         else:
-            self._info = info
+            info = {}
+        if not isinstance(info, dict):
+            log.warning(
+                "Invalid top-level structure (expected dict, got %s)"
+                " in JSON information file at path: %s",
+                type(info).__name__,
+                self._info_file,
+            )
+            info = {}
+        self._info = info
 
-        try:
-            author = tuple(info.get("author", []))
-        except ValueError:
-            author = ()
-        self.author = author
-
-        self.install_msg = info.get("install_msg")
-        self.short = info.get("short")
-        self.description = info.get("description")
+        update_mixin(self, REPO_SCHEMA)