bcb7eddb63
We're seeing crashes during this data migration step. We fail to init the OWSUserProfile from the Row result returned from the SQLite fetch request. It's likely we're indexing into an out-of-bounds index on Row. (Row._checkIndex is inlined so we can't be sure) GRDB caches the sqlite3_column_count during Row.init and uses that to determine if a subscript access is out-of-bounds. From what I can tell in an amateur reading of sqlite3.c, that just pulls the nResColumn from the prepared statement. SQLite will determine the number of result columns during statement prep, but the column count can change if the table schema changes: > If the database schema changes, instead of returning SQLITE_SCHEMA as it always used to do, sqlite3_step() will automatically recompile the SQL statement and try to run it again. As many as SQLITE_MAX_SCHEMA_RETRY retries will occur before sqlite3_step() gives up and returns an error. We're nesting a deferred read transaction inside of our data migration's immediate transaction. This read is using a different sqlite connection that the connection performing our migrations. So its understanding of the schema is stale and because it's in a deferred transaction it won't figure this out until we call _step(). Once we call _step(), sqlite will realize that the table schema has changed and recompile the prepared statement while opening the deferred transaction. After this, the sqlite_column_count is correct. But Row still has the incorrect value cached from before the schema was resolved. So by the time we try and init our OWSUserProfile, Row falsely asserts that we're indexing beyond the column count by comparing against a stale version of the column count. The fix: Rework the data migration to avoid nesting a deferred read transaction. This is incorrect behavior. Now that our read is using our already open write transaction with the same connection handle, it's understanding of the schema is up-to-date during statement prep. So Row.init grabs the current column count. |
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| appearance | ||
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| categories | ||
| contacts | ||
| environment | ||
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| profiles | ||
| Storage Service | ||
| utils | ||
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| Info.plist | ||
| SignalMessaging-Prefix.pch | ||
| SignalMessaging.h | ||