Allow initializing library without default VFS

[simolus3]

With patched SQLite sources, sqlite3_initialize() calls sqlite3mc_initialize(), which tries to install an encryption-wrapper as the default VFS.

I have a setup where I'm using SQLite in a way that doesn't have any VFS registered by the time sqlite3_initialize() completes (it's a custom wasm build where the host installs a VFS per opened database, so there is no default VFS).

So since sqlite3mc_initialize() expects a default VFS, and I should really call sqlite3_initialize() before adding my VFS implementations, it's hard for me to initialize the library properly. Since upstream SQLite works without a VFS in sqlite3_initialize(), could SQLite3MultipleCiphers be changed to also support that? I guess it would be enough if sqlite3mc_vfs_create(NULL, 1) was only called if sqlite3_vfs_find(NULL) is non-null?

[utelle]

With patched SQLite sources, sqlite3_initialize() calls sqlite3mc_initialize(), which tries to install an encryption-wrapper as the default VFS.

Correct. And if no default VFS is found, an error code is returned (which will prevent proper initialization). Most likely an unwanted side effect in the initialization phase.

I have a setup where I'm using SQLite in a way that doesn't have any VFS registered by the time sqlite3_initialize() completes (it's a custom wasm build where the host installs a VFS per opened database, so there is no default VFS).

In such a case you will have to establish the encryption VFS shim for the real VFS yourself, of course.

So since sqlite3mc_initialize() expects a default VFS, and I should really call sqlite3_initialize() before adding my VFS implementations, it's hard for me to initialize the library properly. Since upstream SQLite works without a VFS in sqlite3_initialize(), could SQLite3MultipleCiphers be changed to also support that? I guess it would be enough if sqlite3mc_vfs_create(NULL, 1) was only called if sqlite3_vfs_find(NULL) is non-null?

Yes, checking whether a default VFS exists and not calling sqlite3mc_vfs_create(NULL, 1) if it doesn't, is certainly the right approach.

I will apply this change for the next version. Most likely, SQLite 3.51.0 will be officially released soon. Expect a new version of SQLite Multiple Ciphers shortly thereafter.

[utelle]

A fix was applied in commit a073a59.

SQLite 3.51.0 was released yesterday. A SQLite3MC release will follow within the next days.

[simolus3]

Thank you!