Fix vtab::Module lifetime

src/vtab/array.rs

@@ -33,8 +33,8 @@ use std::rc::Rc;
 use crate::ffi;
 use crate::types::{ToSql, ToSqlOutput, Value};
 use crate::vtab::{
-    eponymous_only_module, Context, IndexConstraintOp, IndexInfo, Module, VTab, VTabConnection,
-    VTabCursor, Values,
+    eponymous_only_module, Context, IndexConstraintOp, IndexInfo, VTab, VTabConnection, VTabCursor,
+    Values,
 };
 use crate::{Connection, Result};
 
@@ -57,11 +57,7 @@ impl ToSql for Array {
 /// `feature = "array"` Register the "rarray" module.
 pub fn load_module(conn: &Connection) -> Result<()> {
     let aux: Option<()> = None;
-    conn.create_module("rarray", &ARRAY_MODULE, aux)
-}
-
-lazy_static::lazy_static! {
-    static ref ARRAY_MODULE: Module<ArrayTab> = eponymous_only_module::<ArrayTab>(1);
+    conn.create_module("rarray", eponymous_only_module::<ArrayTab>(), aux)
 }
 
 // Column numbers

src/vtab/csvtab.rs

@@ -30,7 +30,7 @@ use crate::ffi;
 use crate::types::Null;
 use crate::vtab::{
     dequote, escape_double_quote, parse_boolean, read_only_module, Context, CreateVTab, IndexInfo,
-    Module, VTab, VTabConnection, VTabCursor, Values,
+    VTab, VTabConnection, VTabCursor, Values,
 };
 use crate::{Connection, Error, Result};
 
@@ -47,11 +47,7 @@ use crate::{Connection, Error, Result};
 /// ```
 pub fn load_module(conn: &Connection) -> Result<()> {
     let aux: Option<()> = None;
-    conn.create_module("csv", &CSV_MODULE, aux)
-}
-
-lazy_static::lazy_static! {
-    static ref CSV_MODULE: Module<CSVTab> = read_only_module::<CSVTab>(1);
+    conn.create_module("csv", read_only_module::<CSVTab>(), aux)
 }
 
 /// An instance of the CSV virtual table

src/vtab/mod.rs

@@ -60,7 +60,7 @@ use crate::{str_to_cstring, Connection, Error, InnerConnection, Result};
 /// `feature = "vtab"` Virtual table module
 ///
 /// (See [SQLite doc](https://sqlite.org/c3ref/module.html))
-#[repr(C)]
+#[repr(transparent)]
 pub struct Module<T: VTab> {
     base: ffi::sqlite3_module,
     phantom: PhantomData<T>,
@@ -69,21 +69,31 @@ pub struct Module<T: VTab> {
 unsafe impl<T: VTab> Send for Module<T> {}
 unsafe impl<T: VTab> Sync for Module<T> {}
 
-// Used as a trailing initializer for sqlite3_module -- this way we avoid having
-// the build fail if buildtime_bindgen is on
-fn zeroed_module() -> ffi::sqlite3_module {
-    // This is safe, as bindgen-generated structs are allowed to be zeroed.
-    unsafe { std::mem::MaybeUninit::zeroed().assume_init() }
+union ModuleZeroHack {
+    bytes: [u8; std::mem::size_of::<ffi::sqlite3_module>()],
+    module: ffi::sqlite3_module,
 }
 
+// Used as a trailing initializer for sqlite3_module -- this way we avoid having
+// the build fail if buildtime_bindgen is on. This is safe, as bindgen-generated
+// structs are allowed to be zeroed.
+const ZERO_MODULE: ffi::sqlite3_module = unsafe {
+    ModuleZeroHack {
+        bytes: [0u8; std::mem::size_of::<ffi::sqlite3_module>()],
+    }
+    .module
+};
+
 /// `feature = "vtab"` Create a read-only virtual table implementation.
 ///
 /// Step 2 of [Creating New Virtual Table Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
-pub fn read_only_module<T: CreateVTab>(version: c_int) -> Module<T> {
+pub fn read_only_module<T: CreateVTab>() -> &'static Module<T> {
     // The xConnect and xCreate methods do the same thing, but they must be
     // different so that the virtual table is not an eponymous virtual table.
-    let ffi_module = ffi::sqlite3_module {
-        iVersion: version,
+    &Module {
+        base: ffi::sqlite3_module {
+            // We don't use V3
+            iVersion: 2, // We don't use V2 or V3 features in read_only_module types
             xCreate: Some(rust_create::<T>),
             xConnect: Some(rust_connect::<T>),
             xBestIndex: Some(rust_best_index::<T>),
@@ -106,10 +116,8 @@ pub fn read_only_module<T: CreateVTab>(version: c_int) -> Module<T> {
             xSavepoint: None,
             xRelease: None,
             xRollbackTo: None,
-        ..zeroed_module()
-    };
-    Module {
-        base: ffi_module,
+            ..ZERO_MODULE
+        },
         phantom: PhantomData::<T>,
     }
 }
@@ -117,12 +125,14 @@ pub fn read_only_module<T: CreateVTab>(version: c_int) -> Module<T> {
 /// `feature = "vtab"` Create an eponymous only virtual table implementation.
 ///
 /// Step 2 of [Creating New Virtual Table Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
-pub fn eponymous_only_module<T: VTab>(version: c_int) -> Module<T> {
+pub fn eponymous_only_module<T: VTab>() -> &'static Module<T> {
     // A virtual table is eponymous if its xCreate method is the exact same function
     // as the xConnect method For eponymous-only virtual tables, the xCreate
     // method is NULL
-    let ffi_module = ffi::sqlite3_module {
-        iVersion: version,
+    &Module {
+        base: ffi::sqlite3_module {
+            // We don't use V3
+            iVersion: 2,
             xCreate: None,
             xConnect: Some(rust_connect::<T>),
             xBestIndex: Some(rust_best_index::<T>),
@@ -145,10 +155,8 @@ pub fn eponymous_only_module<T: VTab>(version: c_int) -> Module<T> {
             xSavepoint: None,
             xRelease: None,
             xRollbackTo: None,
-        ..zeroed_module()
-    };
-    Module {
-        base: ffi_module,
+            ..ZERO_MODULE
+        },
         phantom: PhantomData::<T>,
     }
 }
@@ -583,11 +591,12 @@ impl<'a> Iterator for ValueIter<'a> {
 impl Connection {
     /// `feature = "vtab"` Register a virtual table implementation.
     ///
-    /// Step 3 of [Creating New Virtual Table Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
+    /// Step 3 of [Creating New Virtual Table
+    /// Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
     pub fn create_module<T: VTab>(
         &self,
         module_name: &str,
-        module: &Module<T>,
+        module: &'static Module<T>,
         aux: Option<T::Aux>,
     ) -> Result<()> {
         self.db.borrow_mut().create_module(module_name, module, aux)
@@ -598,7 +607,7 @@ impl InnerConnection {
     fn create_module<T: VTab>(
         &mut self,
         module_name: &str,
-        module: &Module<T>,
+        module: &'static Module<T>,
         aux: Option<T::Aux>,
     ) -> Result<()> {
         let c_name = str_to_cstring(module_name)?;

src/vtab/series.rs

@@ -9,19 +9,15 @@ use std::os::raw::c_int;
 use crate::ffi;
 use crate::types::Type;
 use crate::vtab::{
-    eponymous_only_module, Context, IndexConstraintOp, IndexInfo, Module, VTab, VTabConnection,
-    VTabCursor, Values,
+    eponymous_only_module, Context, IndexConstraintOp, IndexInfo, VTab, VTabConnection, VTabCursor,
+    Values,
 };
 use crate::{Connection, Result};
 
 /// `feature = "series"` Register the "generate_series" module.
 pub fn load_module(conn: &Connection) -> Result<()> {
     let aux: Option<()> = None;
-    conn.create_module("generate_series", &SERIES_MODULE, aux)
-}
-
-lazy_static::lazy_static! {
-    static ref SERIES_MODULE: Module<SeriesTab> = eponymous_only_module::<SeriesTab>(1);
+    conn.create_module("generate_series", eponymous_only_module::<SeriesTab>(), aux)
 }
 
 // Column numbers

tests/vtab.rs

@@ -11,7 +11,7 @@ fn test_dummy_module() {
     use rusqlite::{version_number, Connection, Result};
     use std::os::raw::c_int;
 
-    let module = eponymous_only_module::<DummyTab>(1);
+    let module = eponymous_only_module::<DummyTab>();
 
     #[repr(C)]
     struct DummyTab {
@@ -19,7 +19,7 @@ fn test_dummy_module() {
         base: sqlite3_vtab,
     }
 
-    impl VTab for DummyTab {
+    unsafe impl VTab for DummyTab {
         type Aux = ();
         type Cursor = DummyTabCursor;
 
@@ -53,7 +53,7 @@ fn test_dummy_module() {
         row_id: i64,
     }
 
-    impl VTabCursor for DummyTabCursor {
+    unsafe impl VTabCursor for DummyTabCursor {
         fn filter(
             &mut self,
             _idx_num: c_int,