From 254b21f3ecc43d4d844e6ded55378673b913b5c8 Mon Sep 17 00:00:00 2001
From: Florian Bruhin <me@the-compiler.org>
Date: Thu, 18 Mar 2021 10:28:53 +0100
Subject: Try to recover from CompletionMetaInfo with unexpected structure

Fixes #6302
---
 qutebrowser/browser/history.py     | 24 +++++++++++++++++++++---
 qutebrowser/misc/sql.py            |  8 ++++----
 tests/unit/browser/test_history.py | 22 ++++++++++++++++++++++
 3 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/qutebrowser/browser/history.py b/qutebrowser/browser/history.py
index ef4650a35..9eaa88760 100644
--- a/qutebrowser/browser/history.py
+++ b/qutebrowser/browser/history.py
@@ -92,8 +92,11 @@ class CompletionMetaInfo(sql.SqlTable):
     }
 
     def __init__(self, parent=None):
-        super().__init__("CompletionMetaInfo", ['key', 'value'],
-                         constraints={'key': 'PRIMARY KEY'})
+        self._fields = ['key', 'value']
+        self._constraints = {'key': 'PRIMARY KEY'}
+        super().__init__(
+            "CompletionMetaInfo", self._fields, constraints=self._constraints)
+
         if sql.user_version_changed():
             self._init_default_values()
 
@@ -101,6 +104,15 @@ class CompletionMetaInfo(sql.SqlTable):
         if key not in self.KEYS:
             raise KeyError(key)
 
+    def try_recover(self):
+        """Try recovering the table structure.
+
+        This should be called if getting a value via __getattr__ failed. In theory, this
+        should never happen, in practice, it does.
+        """
+        self._create_table(self._fields, constraints=self._constraints, force=True)
+        self._init_default_values()
+
     def _init_default_values(self):
         for key, default in self.KEYS.items():
             if key not in self:
@@ -164,7 +176,13 @@ class WebHistory(sql.SqlTable):
         self.completion = CompletionHistory(parent=self)
         self.metainfo = CompletionMetaInfo(parent=self)
 
-        rebuild_completion = self.metainfo['force_rebuild']
+        try:
+            rebuild_completion = self.metainfo['force_rebuild']
+        except sql.BugError:
+            log.sql.warning("Failed to access meta info, trying to recover...",
+                            exc_info=True)
+            self.metainfo.try_recover()
+            rebuild_completion = self.metainfo['force_rebuild']
 
         if sql.user_version_changed():
             # If the DB user version changed, run a full cleanup and rebuild the
diff --git a/qutebrowser/misc/sql.py b/qutebrowser/misc/sql.py
index 7a3626f6e..68c0fd538 100644
--- a/qutebrowser/misc/sql.py
+++ b/qutebrowser/misc/sql.py
@@ -351,13 +351,13 @@ class SqlTable(QObject):
         self._name = name
         self._create_table(fields, constraints)
 
-    def _create_table(self, fields, constraints):
+    def _create_table(self, fields, constraints, *, force=False):
         """Create the table if the database is uninitialized.
 
-        If the table already exists, this does nothing, so it can e.g. be called on
-        every user_version change.
+        If the table already exists, this does nothing (except with force=True), so it
+        can e.g. be called on every user_version change.
         """
-        if not user_version_changed():
+        if not user_version_changed() and not force:
             return
 
         constraints = constraints or {}
diff --git a/tests/unit/browser/test_history.py b/tests/unit/browser/test_history.py
index 9b08de30d..1ca708ec8 100644
--- a/tests/unit/browser/test_history.py
+++ b/tests/unit/browser/test_history.py
@@ -508,6 +508,28 @@ class TestCompletionMetaInfo:
         metainfo['excluded_patterns'] = value
         assert metainfo['excluded_patterns'] == value
 
+    # FIXME: It'd be good to test those two things via WebHistory (and not just
+    # CompletionMetaInfo in isolation), but we can't do that right now - see the
+    # docstring of TestRebuild for details.
+
+    def test_recovery_no_key(self, metainfo):
+        metainfo.delete('key', 'force_rebuild')
+
+        with pytest.raises(sql.BugError, match='No result for single-result query'):
+            metainfo['force_rebuild']
+
+        metainfo.try_recover()
+        assert not metainfo['force_rebuild']
+
+    def test_recovery_no_table(self, metainfo):
+        sql.Query("DROP TABLE CompletionMetaInfo").run()
+
+        with pytest.raises(sql.BugError, match='no such table: CompletionMetaInfo'):
+            metainfo['force_rebuild']
+
+        metainfo.try_recover()
+        assert not metainfo['force_rebuild']
+
 
 class TestHistoryProgress:
 
-- 
cgit v1.2.3-54-g00ecf