Function c4_setTempDir 

pub unsafe extern "C" fn c4_setTempDir(
    path: C4String,
    err: *mut C4Error,
) -> bool

Wiring call for platforms without discoverable temporary directories. Simply sets the SQLite temp directory so that it can write its temporary files without error. Several platforms need to do this, but not all need to use this API. @param path The path to a writable directory for temporary files for SQLite @param err If an error happens (e.g. it is an error to call this function twice), this parameter records it. @note If you do call this function, you should call it before opening any databases. @note Needless to say, the directory must already exist.