Add setAuthorizer method to SQLite3 (implement userland authorizer)

[bohwaz]

Adds the possibility to define a userland callback that will be used to authorize or not an action on the database.

This allows to effectively implement access restrictions to a SQLite database.

See https://www.sqlite.org/c3ref/set_authorizer.html for details and https://www.sqlite.org/c3ref/c_alter_table.html for action codes and parameters passed to the callback.

The callback will receive 1 to 5 parameters:

• int $action_code refers to one of the codes mentioned in the SQLite doc. All the codes are available as constants of the SQLite3 class.
• nullable string arguments 1 to 4 contain various data passed on by SQLite, usually table name, column name, etc.

The callback must return either SQLite3::OK, SQLite3::IGNORE or SQLite3::DENY. Anything else will trigger an error and will be treated as DENY.

It is possible to disable a previously-set authorizer by passing NULL to the setAuthorizer method.

This patch is also available against the PHP 7.4 branch, if needed.

[bohwaz]

Seems that I have a memory leak somewhere, will try to understand where it comes from on tomorrow.

[bohwaz]

OK I checked and added some stuff, but I can't find where the leak is coming from :( anyone can help me?

[cmb69]

Thanks for the PR! Looks like very useful functionality; I'll try to find some time for a thorough review. :)

Regarding the memory leak: it seems to me that you have to release db_obj->authorizer_fci.function_name in php_sqlite3_object_free_storage().

[bohwaz]

Regarding the memory leak: it seems to me that you have to release db_obj->authorizer_fci.function_name in php_sqlite3_object_free_storage().

Ah yes of course, I didn't think about that, I was sure it was coming from something I missed in using the params inside the fci! Thanks!

[cmb69]

Thanks a lot! I'm generally fine with this, but I think some minor issues should be addressed (see below).

[bohwaz]

Thanks for the review @cmb69 all very good and valid points, I'll fix that ASAP :)

[bohwaz]

@cmb69 everything should be fixed, thank you.

[cmb69]

Thanks @bohwaz! LGTM now.

If there are no objections, I'll merge this in a week.

[cmb69]

Applied as 3958592. Thanks again @bohwaz – useful new feature!