story-kit: merge 260_refactor_upgrade_libsqlite3_sys

vendor/rusqlite/examples/loadable_extension.rs

@@ -0,0 +1,49 @@
+//! Adaptation of https://sqlite.org/loadext.html#programming_loadable_extensions
+//!
+//! # build
+//! ```sh
+//! cargo build --example loadable_extension --features "loadable_extension functions trace"
+//! ```
+//!
+//! # test
+//! ```sh
+//! sqlite> .log on
+//! sqlite> .load target/debug/examples/libloadable_extension.so
+//! (28) Rusqlite extension initialized
+//! sqlite> SELECT rusqlite_test_function();
+//! Rusqlite extension loaded correctly!
+//! ```
+use std::os::raw::{c_char, c_int};
+
+use rusqlite::ffi;
+use rusqlite::functions::FunctionFlags;
+use rusqlite::types::{ToSqlOutput, Value};
+use rusqlite::{Connection, Result};
+
+/// Entry point for SQLite to load the extension.
+/// See <https://sqlite.org/c3ref/load_extension.html> on this function's name and usage.
+/// # Safety
+/// This function is called by SQLite and must be safe to call.
+#[no_mangle]
+pub unsafe extern "C" fn sqlite3_extension_init(
+    db: *mut ffi::sqlite3,
+    pz_err_msg: *mut *mut c_char,
+    p_api: *mut ffi::sqlite3_api_routines,
+) -> c_int {
+    Connection::extension_init2(db, pz_err_msg, p_api, extension_init)
+}
+
+fn extension_init(db: Connection) -> Result<bool> {
+    db.create_scalar_function(
+        c"rusqlite_test_function",
+        0,
+        FunctionFlags::SQLITE_DETERMINISTIC,
+        |_ctx| {
+            Ok(ToSqlOutput::Owned(Value::Text(
+                "Rusqlite extension loaded correctly!".to_string(),
+            )))
+        },
+    )?;
+    rusqlite::trace::log(ffi::SQLITE_WARNING, "Rusqlite extension initialized");
+    Ok(false)
+}