Loadable extension

Cargo.toml

@@ -50,6 +50,7 @@ bundled-sqlcipher = ["libsqlite3-sys/bundled-sqlcipher", "bundled"]
 bundled-sqlcipher-vendored-openssl = ["libsqlite3-sys/bundled-sqlcipher-vendored-openssl", "bundled-sqlcipher"]
 buildtime_bindgen = ["libsqlite3-sys/buildtime_bindgen"]
 limits = []
+loadable_extension = ["libsqlite3-sys/loadable_extension"]
 hooks = []
 i128_blob = []
 sqlcipher = ["libsqlite3-sys/sqlcipher"]

libsqlite3-sys/Cargo.toml

@@ -2,7 +2,7 @@
 name = "libsqlite3-sys"
 version = "0.26.0"
 authors = ["The rusqlite developers"]
-edition = "2018"
+edition = "2021"
 repository = "https://github.com/rusqlite/rusqlite"
 description = "Native bindings to the libsqlite3 library"
 license = "MIT"
@@ -23,6 +23,7 @@ min_sqlite_version_3_14_0 = ["pkg-config", "vcpkg"]
 # Bundle only the bindings file. Note that this does nothing if
 # `buildtime_bindgen` is enabled.
 bundled_bindings = []
+loadable_extension = ["atomic", "prettyplease", "quote", "regex", "syn"]
 # sqlite3_unlock_notify >= 3.6.12
 unlock_notify = []
 # 3.13.0
@@ -42,9 +43,18 @@ winsqlite3 = []
 
 [dependencies]
 openssl-sys = { version = "0.9", optional = true }
+atomic = { version = "0.5", optional = true }
 
 [build-dependencies]
 bindgen = { version = "0.66", optional = true, default-features = false, features = ["runtime"] }
 pkg-config = { version = "0.3.19", optional = true }
 cc = { version = "1.0", optional = true }
 vcpkg = { version = "0.2", optional = true }
+# for loadable_extension:
+prettyplease = {version = "0.2", optional = true }
+# like bindgen
+quote = { version = "1", optional = true, default-features = false }
+# like bindgen
+regex = { version = "1.5", optional = true, default-features = false, features = ["std", "unicode"] }
+# like bindgen
+syn = { version = "2.0", optional = true, features = ["full", "extra-traits", "visit-mut"] }

libsqlite3-sys/build.rs

@@ -28,8 +28,12 @@ fn is_compiler(compiler_name: &str) -> bool {
 
 /// Copy bindgen file from `dir` to `out_path`.
 fn copy_bindings<T: AsRef<Path>>(dir: &str, bindgen_name: &str, out_path: T) {
-    std::fs::copy(format!("{dir}/{bindgen_name}"), out_path)
-        .expect("Could not copy bindings to output directory");
+    let from = if cfg!(feature = "loadable_extension") {
+        format!("{dir}/{bindgen_name}_ext.rs")
+    } else {
+        format!("{dir}/{bindgen_name}.rs")
+    };
+    std::fs::copy(from, out_path).expect("Could not copy bindings to output directory");
 }
 
 fn main() {
@@ -38,12 +42,14 @@ fn main() {
     if cfg!(feature = "in_gecko") {
         // When inside mozilla-central, we are included into the build with
         // sqlite3.o directly, so we don't want to provide any linker arguments.
-        copy_bindings("sqlite3", "bindgen_bundled_version.rs", out_path);
+        copy_bindings("sqlite3", "bindgen_bundled_version", out_path);
         return;
     }
 
     println!("cargo:rerun-if-env-changed=LIBSQLITE3_SYS_USE_PKG_CONFIG");
-    if env::var_os("LIBSQLITE3_SYS_USE_PKG_CONFIG").map_or(false, |s| s != "0") {
+    if env::var_os("LIBSQLITE3_SYS_USE_PKG_CONFIG").map_or(false, |s| s != "0")
+        || cfg!(feature = "loadable_extension")
+    {
         build_linked::main(&out_dir, &out_path);
     } else if cfg!(all(
         feature = "sqlcipher",
@@ -106,7 +112,7 @@ mod build_bundled {
         }
         #[cfg(not(feature = "buildtime_bindgen"))]
         {
-            super::copy_bindings(lib_name, "bindgen_bundled_version.rs", out_path);
+            super::copy_bindings(lib_name, "bindgen_bundled_version", out_path);
         }
         println!("cargo:rerun-if-changed={lib_name}/sqlite3.c");
         println!("cargo:rerun-if-changed=sqlite3/wasm32-wasi-vfs.c");
@@ -344,11 +350,28 @@ impl From<HeaderLocation> for String {
                         prefix, prefix
                     )
                 });
-                header.push_str("/sqlite3.h");
+                header.push_str(if cfg!(feature = "loadable_extension") {
+                    "/sqlite3ext.h"
+                } else {
+                    "/sqlite3.h"
+                });
                 header
             }
-            HeaderLocation::Wrapper => "wrapper.h".into(),
-            HeaderLocation::FromPath(path) => format!("{}/sqlite3.h", path),
+            HeaderLocation::Wrapper => if cfg!(feature = "loadable_extension") {
+                "wrapper_ext.h"
+            } else {
+                "wrapper.h"
+            }
+            .into(),
+            HeaderLocation::FromPath(path) => format!(
+                "{}/{}",
+                path,
+                if cfg!(feature = "loadable_extension") {
+                    "sqlite3ext.h"
+                } else {
+                    "sqlite3.h"
+                }
+            ),
         }
     }
 }
@@ -375,12 +398,13 @@ mod build_linked {
             // on buildtime_bindgen instead, but this is still supported as we
             // have runtime version checks and there are good reasons to not
             // want to run bindgen.
-            super::copy_bindings(lib_name(), "bindgen_bundled_version.rs", out_path);
+            super::copy_bindings(lib_name(), "bindgen_bundled_version", out_path);
         } else {
             bindings::write_to_out_dir(header, out_path);
         }
     }
 
+    #[cfg(not(feature = "loadable_extension"))]
     fn find_link_mode() -> &'static str {
         // If the user specifies SQLITE3_STATIC (or SQLCIPHER_STATIC), do static
         // linking, unless it's explicitly set to 0.
@@ -404,9 +428,11 @@ mod build_linked {
         // `links=` value in our Cargo.toml) to get this value. This might be
         // useful if you need to ensure whatever crypto library sqlcipher relies
         // on is available, for example.
+        #[cfg(not(feature = "loadable_extension"))]
         println!("cargo:link-target={link_lib}");
 
         if win_target() && cfg!(feature = "winsqlite3") {
+            #[cfg(not(feature = "loadable_extension"))]
             println!("cargo:rustc-link-lib=dylib={link_lib}");
             return HeaderLocation::Wrapper;
         }
@@ -416,6 +442,7 @@ mod build_linked {
             // Try to use pkg-config to determine link commands
             let pkgconfig_path = Path::new(&dir).join("pkgconfig");
             env::set_var("PKG_CONFIG_PATH", pkgconfig_path);
+            #[cfg(not(feature = "loadable_extension"))]
             if pkg_config::Config::new().probe(link_lib).is_err() {
                 // Otherwise just emit the bare minimum link commands.
                 println!("cargo:rustc-link-lib={}={link_lib}", find_link_mode());
@@ -443,6 +470,7 @@ mod build_linked {
             // request and hope that the library exists on the system paths. We used to
             // output /usr/lib explicitly, but that can introduce other linking problems;
             // see https://github.com/rusqlite/rusqlite/issues/207.
+            #[cfg(not(feature = "loadable_extension"))]
             println!("cargo:rustc-link-lib={}={link_lib}", find_link_mode());
             HeaderLocation::Wrapper
         }
@@ -470,7 +498,7 @@ mod bindings {
 
     use std::path::Path;
 
-    static PREBUILT_BINDGENS: &[&str] = &["bindgen_3.14.0.rs"];
+    static PREBUILT_BINDGENS: &[&str] = &["bindgen_3.14.0"];
 
     pub fn write_to_out_dir(_header: HeaderLocation, out_path: &Path) {
         let name = PREBUILT_BINDGENS[PREBUILT_BINDGENS.len() - 1];
@@ -522,10 +550,14 @@ mod bindings {
             .disable_nested_struct_naming()
             .trust_clang_mangling(false)
             .header(header.clone())
-            .parse_callbacks(Box::new(SqliteTypeChooser))
-            .blocklist_function("sqlite3_auto_extension")
-            .raw_line(
-                r#"extern "C" {
+            .parse_callbacks(Box::new(SqliteTypeChooser));
+        if cfg!(feature = "loadable_extension") {
+            bindings = bindings.ignore_functions(); // see generate_functions
+        } else {
+            bindings = bindings
+                .blocklist_function("sqlite3_auto_extension")
+                .raw_line(
+                    r#"extern "C" {
     pub fn sqlite3_auto_extension(
         xEntryPoint: ::std::option::Option<
             unsafe extern "C" fn(
@@ -536,10 +568,10 @@ mod bindings {
         >,
     ) -> ::std::os::raw::c_int;
 }"#,
-            )
-            .blocklist_function("sqlite3_cancel_auto_extension")
-            .raw_line(
-                r#"extern "C" {
+                )
+                .blocklist_function("sqlite3_cancel_auto_extension")
+                .raw_line(
+                    r#"extern "C" {
     pub fn sqlite3_cancel_auto_extension(
         xEntryPoint: ::std::option::Option<
             unsafe extern "C" fn(
@@ -550,7 +582,8 @@ mod bindings {
         >,
     ) -> ::std::os::raw::c_int;
 }"#,
-            );
+                );
+        }
 
         if cfg!(any(feature = "sqlcipher", feature = "bundled-sqlcipher")) {
             bindings = bindings.clang_arg("-DSQLITE_HAS_CODEC");
@@ -621,11 +654,204 @@ mod bindings {
                 .blocklist_item("__.*");
         }
 
-        bindings
+        let bindings = bindings
             .layout_tests(false)
             .generate()
-            .unwrap_or_else(|_| panic!("could not run bindgen on header {}", header))
-            .write_to_file(out_path)
-            .unwrap_or_else(|_| panic!("Could not write to {:?}", out_path));
+            .unwrap_or_else(|_| panic!("could not run bindgen on header {}", header));
+
+        if cfg!(feature = "loadable_extension") {
+            let mut output = Vec::new();
+            bindings
+                .write(Box::new(&mut output))
+                .expect("could not write output of bindgen");
+            let mut output = String::from_utf8(output).expect("bindgen output was not UTF-8?!");
+            super::loadable_extension::generate_functions(&header, &mut output);
+            std::fs::write(out_path, output.as_bytes())
+        } else {
+            bindings.write_to_file(out_path)
+        }
+        .unwrap_or_else(|_| panic!("Could not write to {:?}", out_path));
+    }
+}
+
+#[cfg(all(feature = "buildtime_bindgen", feature = "loadable_extension"))]
+mod loadable_extension {
+    use std::collections::HashMap;
+
+    /// try to generate similar rust code for all `#define sqlite3_xyz
+    /// sqlite3_api->abc` macros` in sqlite3ext.h
+    pub fn generate_functions(header: &str, output: &mut String) {
+        // (1) parse macros in sqlite3ext.h
+        let mappings = parse_macros(header);
+        // (2) parse sqlite3_api_routines fields from bindgen output
+        let ast: syn::File = syn::parse_str(output).expect("could not parse bindgen output");
+        let sqlite3_api_routines: syn::ItemStruct = ast
+            .items
+            .into_iter()
+            .find_map(|i| {
+                if let syn::Item::Struct(s) = i {
+                    if s.ident == "sqlite3_api_routines" {
+                        Some(s)
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                }
+            })
+            .expect("could not find sqlite3_api_routines");
+        let sqlite3_api_routines_ident = sqlite3_api_routines.ident;
+        let p_api = quote::format_ident!("p_api");
+        let mut stores = Vec::new();
+        // (3) `#define sqlite3_xyz sqlite3_api->abc` => `pub unsafe fn
+        // sqlite3_xyz(args) -> ty {...}` for each `abc` field:
+        for field in sqlite3_api_routines.fields {
+            let ident = field.ident.expect("unamed field");
+            let span = ident.span();
+            let name = ident.to_string();
+            if name == "vmprintf" || name == "xvsnprintf" || name == "str_vappendf" {
+                continue; // skip va_list
+            }
+            let sqlite3_name = mappings
+                .get(&name)
+                .unwrap_or_else(|| panic!("no mapping for {name}"));
+            let ptr_name =
+                syn::Ident::new(format!("__{}", sqlite3_name.to_uppercase()).as_ref(), span);
+            let sqlite3_fn_name = syn::Ident::new(sqlite3_name, span);
+            let method =
+                extract_method(&field.ty).unwrap_or_else(|| panic!("unexpected type for {name}"));
+            let arg_names: syn::punctuated::Punctuated<&syn::Ident, syn::token::Comma> = method
+                .inputs
+                .iter()
+                .map(|i| &i.name.as_ref().unwrap().0)
+                .collect();
+            let args = &method.inputs;
+            // vtab_config/sqlite3_vtab_config: ok
+            let varargs = &method.variadic;
+            if varargs.is_some() && "db_config" != name && "log" != name && "vtab_config" != name {
+                continue; // skip ...
+            }
+            let ty = &method.output;
+            let tokens = if "db_config" == name {
+                quote::quote! {
+                    static #ptr_name: ::atomic::Atomic<Option<unsafe extern "C" fn(#args #varargs) #ty>> = ::atomic::Atomic::new(None);
+                    pub unsafe fn #sqlite3_fn_name(#args arg3: ::std::os::raw::c_int, arg4: *mut ::std::os::raw::c_int) #ty {
+                        let fun = #ptr_name.load(::atomic::Ordering::Acquire).expect("SQLite API not initialized");
+                        (fun)(#arg_names, arg3, arg4)
+                    }
+                }
+            } else if "log" == name {
+                quote::quote! {
+                    static #ptr_name: ::atomic::Atomic<Option<unsafe extern "C" fn(#args #varargs) #ty>> = ::atomic::Atomic::new(None);
+                    pub unsafe fn #sqlite3_fn_name(#args arg3: *const ::std::os::raw::c_char) #ty {
+                        let fun = #ptr_name.load(::atomic::Ordering::Acquire).expect("SQLite API not initialized");
+                        (fun)(#arg_names, arg3)
+                    }
+                }
+            } else {
+                quote::quote! {
+                    static #ptr_name: ::atomic::Atomic<Option<unsafe extern "C" fn(#args #varargs) #ty>> = ::atomic::Atomic::new(None);
+                    pub unsafe fn #sqlite3_fn_name(#args) #ty {
+                        let fun = #ptr_name.load(::atomic::Ordering::Acquire).expect("SQLite API not initialized or SQLite feature omitted");
+                        (fun)(#arg_names)
+                    }
+                }
+            };
+            output.push_str(&prettyplease::unparse(
+                &syn::parse2(tokens).expect("could not parse quote output"),
+            ));
+            output.push('\n');
+            stores.push(quote::quote! {
+                #ptr_name.store(
+                    (*#p_api).#ident,
+                    ::atomic::Ordering::Release,
+                );
+            });
+        }
+        // (4) generate rust code similar to SQLITE_EXTENSION_INIT2 macro
+        let tokens = quote::quote! {
+            /// Loadable extension initialization error
+            #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+            #[non_exhaustive]
+            pub enum InitError {
+                /// Invalid sqlite3_api_routines pointer
+                NullApiPointer,
+                /// Version mismatch between the extension and the SQLite3 library
+                VersionMismatch{compile_time: i32, runtime: i32},
+                /// Invalid function pointer in one of sqlite3_api_routines fields
+                NullFunctionPointer,
+            }
+            impl ::std::fmt::Display for InitError {
+                fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                    match *self {
+                        InitError::NullApiPointer => write!(f, "Invalid sqlite3_api_routines pointer"),
+                        InitError::VersionMismatch{compile_time, runtime} => write!(f, "SQLite version mismatch: {runtime} < {compile_time}"),
+                        InitError::NullFunctionPointer => write!(f, "Some sqlite3_api_routines fields are null"),
+                    }
+                }
+            }
+            /// Like SQLITE_EXTENSION_INIT2 macro
+            pub unsafe fn rusqlite_extension_init2(#p_api: *mut #sqlite3_api_routines_ident) -> ::std::result::Result<(),InitError> {
+                if #p_api.is_null() {
+                    return Err(InitError::NullApiPointer);
+                }
+                if let Some(fun) = (*#p_api).libversion_number {
+                    let version = fun();
+                    if SQLITE_VERSION_NUMBER > version {
+                        return Err(InitError::VersionMismatch{compile_time: SQLITE_VERSION_NUMBER, runtime: version});
+                    }
+                } else {
+                    return Err(InitError::NullFunctionPointer);
+                }
+                #(#stores)*
+                Ok(())
+            }
+        };
+        output.push_str(&prettyplease::unparse(
+            &syn::parse2(tokens).expect("could not parse quote output"),
+        ));
+        output.push('\n');
+    }
+
+    // Load all `#define sqlite3_xyz sqlite3_api->abc` in sqlite3ext.h
+    // as a map `{abc => sqlite3_xyz}`
+    // See https://github.com/rust-lang/rust-bindgen/issues/2544
+    fn parse_macros(header: &str) -> HashMap<String, String> {
+        use regex::Regex;
+        use std::fs::File;
+        use std::io::{BufRead, BufReader};
+        let re = Regex::new(r"^#define\s+(sqlite3_\w+)\s+sqlite3_api->(\w+)").unwrap();
+        let f = File::open(header).expect("could not read sqlite3ext.h");
+        let f = BufReader::new(f);
+        let mut mappings = HashMap::new();
+        for line in f.lines() {
+            let line = line.expect("could not read line");
+            if let Some(caps) = re.captures(&line) {
+                mappings.insert(
+                    caps.get(2).unwrap().as_str().to_owned(),
+                    caps.get(1).unwrap().as_str().to_owned(),
+                );
+            }
+        }
+        mappings
+    }
+
+    fn extract_method(ty: &syn::Type) -> Option<&syn::TypeBareFn> {
+        match ty {
+            syn::Type::Path(tp) => tp.path.segments.last(),
+            _ => None,
+        }
+        .map(|seg| match &seg.arguments {
+            syn::PathArguments::AngleBracketed(args) => args.args.first(),
+            _ => None,
+        })?
+        .map(|arg| match arg {
+            syn::GenericArgument::Type(t) => Some(t),
+            _ => None,
+        })?
+        .map(|ty| match ty {
+            syn::Type::BareFn(r) => Some(r),
+            _ => None,
+        })?
     }
 }

libsqlite3-sys/upgrade.sh

@@ -3,10 +3,10 @@
 SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
 echo "$SCRIPT_DIR"
 cd "$SCRIPT_DIR" || { echo "fatal error" >&2; exit 1; }
-cargo clean
-mkdir -p "$SCRIPT_DIR/../target" "$SCRIPT_DIR/sqlite3"
+cargo clean -p libsqlite3-sys
+TARGET_DIR="$SCRIPT_DIR/../target"
 export SQLITE3_LIB_DIR="$SCRIPT_DIR/sqlite3"
-export SQLITE3_INCLUDE_DIR="$SQLITE3_LIB_DIR"
+mkdir -p "$TARGET_DIR" "$SQLITE3_LIB_DIR"
 
 # Download and extract amalgamation
 SQLITE=sqlite-amalgamation-3420000
@@ -16,13 +16,24 @@ unzip -p "$SQLITE.zip" "$SQLITE/sqlite3.h" > "$SQLITE3_LIB_DIR/sqlite3.h"
 unzip -p "$SQLITE.zip" "$SQLITE/sqlite3ext.h" > "$SQLITE3_LIB_DIR/sqlite3ext.h"
 rm -f "$SQLITE.zip"
 
-# Regenerate bindgen file for sqlite3
+export SQLITE3_INCLUDE_DIR="$SQLITE3_LIB_DIR"
+# Regenerate bindgen file for sqlite3.h
 rm -f "$SQLITE3_LIB_DIR/bindgen_bundled_version.rs"
 cargo update
 # Just to make sure there is only one bindgen.rs file in target dir
-find "$SCRIPT_DIR/../target" -type f -name bindgen.rs -exec rm {} \;
+find "$TARGET_DIR" -type f -name bindgen.rs -exec rm {} \;
 env LIBSQLITE3_SYS_BUNDLING=1 cargo build --features "buildtime_bindgen session" --no-default-features
-find "$SCRIPT_DIR/../target" -type f -name bindgen.rs -exec mv {} "$SQLITE3_LIB_DIR/bindgen_bundled_version.rs" \;
+find "$TARGET_DIR" -type f -name bindgen.rs -exec mv {} "$SQLITE3_LIB_DIR/bindgen_bundled_version.rs" \;
+
+# Regenerate bindgen file for sqlite3ext.h
+# some sqlite3_api_routines fields are function pointers with va_list arg but currently stable Rust doesn't support this type.
+# FIXME how to generate portable bindings without :
+sed -i '' 's/va_list/void*/' "$SQLITE3_LIB_DIR/sqlite3ext.h"
+rm -f "$SQLITE3_LIB_DIR/bindgen_bundled_version_ext.rs"
+find "$TARGET_DIR" -type f -name bindgen.rs -exec rm {} \;
+env LIBSQLITE3_SYS_BUNDLING=1 cargo build --features "buildtime_bindgen loadable_extension" --no-default-features
+find "$TARGET_DIR" -type f -name bindgen.rs -exec mv {} "$SQLITE3_LIB_DIR/bindgen_bundled_version_ext.rs" \;
+git checkout "$SQLITE3_LIB_DIR/sqlite3ext.h"
 
 # Sanity checks
 cd "$SCRIPT_DIR/.." || { echo "fatal error" >&2; exit 1; }

libsqlite3-sys/upgrade_sqlcipher.sh

@@ -3,7 +3,7 @@
 SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
 echo "$SCRIPT_DIR"
 cd "$SCRIPT_DIR" || { echo "fatal error" >&2; exit 1; }
-cargo clean
+cargo clean -p libsqlite3-sys
 mkdir -p "$SCRIPT_DIR/../target" "$SCRIPT_DIR/sqlcipher"
 export SQLCIPHER_LIB_DIR="$SCRIPT_DIR/sqlcipher"
 export SQLCIPHER_INCLUDE_DIR="$SQLCIPHER_LIB_DIR"

libsqlite3-sys/wrapper_ext.h

@@ -0,0 +1,2 @@
+#include "sqlite3ext.h"
+

src/inner_connection.rs

@@ -4,7 +4,7 @@ use std::os::raw::{c_char, c_int};
 use std::path::Path;
 use std::ptr;
 use std::str;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Mutex};
 
 use super::ffi;
@@ -390,7 +390,7 @@ impl Drop for InnerConnection {
     }
 }
 
-#[cfg(not(any(target_arch = "wasm32")))]
+#[cfg(not(any(target_arch = "wasm32", feature = "loadable_extension")))]
 static SQLITE_INIT: std::sync::Once = std::sync::Once::new();
 
 pub static BYPASS_SQLITE_INIT: AtomicBool = AtomicBool::new(false);
@@ -440,7 +440,9 @@ fn ensure_safe_sqlite_threading_mode() -> Result<()> {
             Ok(())
         }
     } else {
+        #[cfg(not(feature = "loadable_extension"))]
         SQLITE_INIT.call_once(|| {
+            use std::sync::atomic::Ordering;
             if BYPASS_SQLITE_INIT.load(Ordering::Relaxed) {
                 return;
             }

src/trace.rs

@@ -8,8 +8,7 @@ use std::ptr;
 use std::time::Duration;
 
 use super::ffi;
-use crate::error::error_from_sqlite_code;
-use crate::{Connection, Result};
+use crate::Connection;
 
 /// Set up the process-wide SQLite error logging callback.
 ///
@@ -25,7 +24,8 @@ use crate::{Connection, Result};
 ///     * It must be threadsafe if SQLite is used in a multithreaded way.
 ///
 /// cf [The Error And Warning Log](http://sqlite.org/errlog.html).
-pub unsafe fn config_log(callback: Option<fn(c_int, &str)>) -> Result<()> {
+#[cfg(not(feature = "loadable_extension"))]
+pub unsafe fn config_log(callback: Option<fn(c_int, &str)>) -> crate::Result<()> {
     extern "C" fn log_callback(p_arg: *mut c_void, err: c_int, msg: *const c_char) {
         let c_slice = unsafe { CStr::from_ptr(msg).to_bytes() };
         let callback: fn(c_int, &str) = unsafe { mem::transmute(p_arg) };
@@ -48,7 +48,7 @@ pub unsafe fn config_log(callback: Option<fn(c_int, &str)>) -> Result<()> {
     if rc == ffi::SQLITE_OK {
         Ok(())
     } else {
-        Err(error_from_sqlite_code(rc, None))
+        Err(crate::error::error_from_sqlite_code(rc, None))
     }
 }
 

tests/deny_single_threaded_sqlite_config.rs

@@ -1,11 +1,11 @@
 //! Ensure we reject connections when SQLite is in single-threaded mode, as it
 //! would violate safety if multiple Rust threads tried to use connections.
 
-use rusqlite::ffi;
-use rusqlite::Connection;
-
+#[cfg(not(feature = "loadable_extension"))]
 #[test]
 fn test_error_when_singlethread_mode() {
+    use rusqlite::ffi;
+    use rusqlite::Connection;
     // put SQLite into single-threaded mode
     unsafe {
         // Note: macOS system SQLite seems to return an error if you attempt to