Possible misuse of sqlite3_column_table_name et al #27776

Original issue at ericsink/SQLitePCL.raw#479

I am concerned about possible problems with the calls to the SQLite column metadata functions (sqlite3_column_database_name, sqlite3_column_table_name, sqlite3_column_origin_name) in this area of the code:

The docs:

https://www.sqlite.org/c3ref/column_database_name.html

say that these functions return NULL when the origin is an expression ... not a column value. And looking at the code, it seems possible that those NULLs would find their way into the call to sqlite3_table_column_metadata. Which would explain the behavior seen in the original issue.