[chore] update latest deps, ensure readme up to date (#1873)

* [chore] update latest deps, ensure readme up to date

* remove double entry

vendor/modernc.org/sqlite/sqlite.go

@@ -10,11 +10,14 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"io"
 	"math"
+	"math/bits"
 	"net/url"
 	"reflect"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -1319,7 +1322,12 @@ func (c *conn) errstr(rc int32) error {
 // Begin starts a transaction.
 //
 // Deprecated: Drivers should implement ConnBeginTx instead (or additionally).
-func (c *conn) Begin() (driver.Tx, error) {
+func (c *conn) Begin() (dt driver.Tx, err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("conn %p: (driver.Tx %p, err %v)", c, dt, err)
+		}()
+	}
 	return c.begin(context.Background(), driver.TxOptions{})
 }
 
@@ -1333,7 +1341,12 @@ func (c *conn) begin(ctx context.Context, opts driver.TxOptions) (t driver.Tx, e
 // Because the sql package maintains a free pool of connections and only calls
 // Close when there's a surplus of idle connections, it shouldn't be necessary
 // for drivers to do their own connection caching.
-func (c *conn) Close() error {
+func (c *conn) Close() (err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("conn %p: err %v", c, err)
+		}()
+	}
 	c.Lock() // Defend against race with .interrupt invoked by context handling.
 
 	defer c.Unlock()
@@ -1362,27 +1375,106 @@ func (c *conn) closeV2(db uintptr) error {
 	return nil
 }
 
+// FunctionImpl describes an [application-defined SQL function]. If Scalar is
+// set, it is treated as a scalar function; otherwise, it is treated as an
+// aggregate function using MakeAggregate.
+//
+// [application-defined SQL function]: https://sqlite.org/appfunc.html
+type FunctionImpl struct {
+	// NArgs is the required number of arguments that the function accepts.
+	// If NArgs is negative, then the function is variadic.
+	NArgs int32
+
+	// If Deterministic is true, the function must always give the same
+	// output when the input parameters are the same. This enables functions
+	// to be used in additional contexts like the WHERE clause of partial
+	// indexes and enables additional optimizations.
+	//
+	// See https://sqlite.org/c3ref/c_deterministic.html#sqlitedeterministic
+	// for more details.
+	Deterministic bool
+
+	// Scalar is called when a scalar function is invoked in SQL. The
+	// argument Values are not valid past the return of the function.
+	Scalar func(ctx *FunctionContext, args []driver.Value) (driver.Value, error)
+
+	// MakeAggregate is called at the beginning of each evaluation of an
+	// aggregate function.
+	MakeAggregate func(ctx FunctionContext) (AggregateFunction, error)
+}
+
+// An AggregateFunction is an invocation of an aggregate or window function. See
+// the documentation for [aggregate function callbacks] and [application-defined
+// window functions] for an overview.
+//
+// [aggregate function callbacks]: https://www.sqlite.org/appfunc.html#the_aggregate_function_callbacks
+// [application-defined window functions]: https://www.sqlite.org/windowfunctions.html#user_defined_aggregate_window_functions
+type AggregateFunction interface {
+	// Step is called for each row of an aggregate function's SQL
+	// invocation. The argument Values are not valid past the return of the
+	// function.
+	Step(ctx *FunctionContext, rowArgs []driver.Value) error
+
+	// WindowInverse is called to remove the oldest presently aggregated
+	// result of Step from the current window. The arguments are those
+	// passed to Step for the row being removed. The argument Values are not
+	// valid past the return of the function.
+	WindowInverse(ctx *FunctionContext, rowArgs []driver.Value) error
+
+	// WindowValue is called to get the current value of an aggregate
+	// function. This is used to return the final value of the function,
+	// whether it is used as a window function or not.
+	WindowValue(ctx *FunctionContext) (driver.Value, error)
+
+	// Final is called after all of the aggregate function's input rows have
+	// been stepped through. No other methods will be called on the
+	// AggregateFunction after calling Final. WindowValue returns the value
+	// from the function.
+	Final(ctx *FunctionContext)
+}
+
 type userDefinedFunction struct {
 	zFuncName uintptr
 	nArg      int32
 	eTextRep  int32
-	xFunc     func(*libc.TLS, uintptr, int32, uintptr)
+	pApp      uintptr
 
+	scalar   bool
 	freeOnce sync.Once
 }
 
 func (c *conn) createFunctionInternal(fun *userDefinedFunction) error {
-	if rc := sqlite3.Xsqlite3_create_function(
-		c.tls,
-		c.db,
-		fun.zFuncName,
-		fun.nArg,
-		fun.eTextRep,
-		0,
-		*(*uintptr)(unsafe.Pointer(&fun.xFunc)),
-		0,
-		0,
-	); rc != sqlite3.SQLITE_OK {
+	var rc int32
+
+	if fun.scalar {
+		rc = sqlite3.Xsqlite3_create_function(
+			c.tls,
+			c.db,
+			fun.zFuncName,
+			fun.nArg,
+			fun.eTextRep,
+			fun.pApp,
+			cFuncPointer(funcTrampoline),
+			0,
+			0,
+		)
+	} else {
+		rc = sqlite3.Xsqlite3_create_window_function(
+			c.tls,
+			c.db,
+			fun.zFuncName,
+			fun.nArg,
+			fun.eTextRep,
+			fun.pApp,
+			cFuncPointer(stepTrampoline),
+			cFuncPointer(finalTrampoline),
+			cFuncPointer(valueTrampoline),
+			cFuncPointer(inverseTrampoline),
+			0,
+		)
+	}
+
+	if rc != sqlite3.SQLITE_OK {
 		return c.errstr(rc)
 	}
 	return nil
@@ -1396,7 +1488,12 @@ func (c *conn) createFunctionInternal(fun *userDefinedFunction) error {
 // Exec may return ErrSkip.
 //
 // Deprecated: Drivers should implement ExecerContext instead.
-func (c *conn) Exec(query string, args []driver.Value) (driver.Result, error) {
+func (c *conn) Exec(query string, args []driver.Value) (dr driver.Result, err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("conn %p, query %q, args %v: (driver.Result %p, err %v)", c, query, args, dr, err)
+		}()
+	}
 	return c.exec(context.Background(), query, toNamedValues(args))
 }
 
@@ -1416,7 +1513,12 @@ func (c *conn) exec(ctx context.Context, query string, args []driver.NamedValue)
 }
 
 // Prepare returns a prepared statement, bound to this connection.
-func (c *conn) Prepare(query string) (driver.Stmt, error) {
+func (c *conn) Prepare(query string) (ds driver.Stmt, err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("conn %p, query %q: (driver.Stmt %p, err %v)", c, query, ds, err)
+		}()
+	}
 	return c.prepare(context.Background(), query)
 }
 
@@ -1433,7 +1535,12 @@ func (c *conn) prepare(ctx context.Context, query string) (s driver.Stmt, err er
 // Query may return ErrSkip.
 //
 // Deprecated: Drivers should implement QueryerContext instead.
-func (c *conn) Query(query string, args []driver.Value) (driver.Rows, error) {
+func (c *conn) Query(query string, args []driver.Value) (dr driver.Rows, err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("conn %p, query %q, args %v: (driver.Rows %p, err %v)", c, query, args, dr, err)
+		}()
+	}
 	return c.query(context.Background(), query, toNamedValues(args))
 }
 
@@ -1491,7 +1598,12 @@ func newDriver() *Driver { return d }
 // not specify one, which SQLite maps to "deferred". More information is
 // available at
 // https://www.sqlite.org/lang_transaction.html#deferred_immediate_and_exclusive_transactions
-func (d *Driver) Open(name string) (driver.Conn, error) {
+func (d *Driver) Open(name string) (conn driver.Conn, err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("name %q: (driver.Conn %p, err %v)", name, conn, err)
+		}()
+	}
 	c, err := newConn(name)
 	if err != nil {
 		return nil, err
@@ -1508,10 +1620,38 @@ func (d *Driver) Open(name string) (driver.Conn, error) {
 
 // FunctionContext represents the context user defined functions execute in.
 // Fields and/or methods of this type may get addedd in the future.
-type FunctionContext struct{}
+type FunctionContext struct {
+	tls *libc.TLS
+	ctx uintptr
+}
 
 const sqliteValPtrSize = unsafe.Sizeof(&sqlite3.Sqlite3_value{})
 
+// RegisterFunction registers a function named zFuncName with nArg arguments.
+// Passing -1 for nArg indicates the function is variadic. The FunctionImpl
+// determines whether the function is deterministic or not, and whether it is a
+// scalar function (when Scalar is defined) or an aggregate function (when
+// Scalar is not defined and MakeAggregate is defined).
+//
+// The new function will be available to all new connections opened after
+// executing RegisterFunction.
+func RegisterFunction(
+	zFuncName string,
+	impl *FunctionImpl,
+) error {
+	return registerFunction(zFuncName, impl)
+}
+
+// MustRegisterFunction is like RegisterFunction but panics on error.
+func MustRegisterFunction(
+	zFuncName string,
+	impl *FunctionImpl,
+) {
+	if err := RegisterFunction(zFuncName, impl); err != nil {
+		panic(err)
+	}
+}
+
 // RegisterScalarFunction registers a scalar function named zFuncName with nArg
 // arguments. Passing -1 for nArg indicates the function is variadic.
 //
@@ -1521,8 +1661,13 @@ func RegisterScalarFunction(
 	zFuncName string,
 	nArg int32,
 	xFunc func(ctx *FunctionContext, args []driver.Value) (driver.Value, error),
-) error {
-	return registerScalarFunction(zFuncName, nArg, sqlite3.SQLITE_UTF8, xFunc)
+) (err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("zFuncName %q, nArg %v, xFunc %p: err %v", zFuncName, nArg, xFunc, err)
+		}()
+	}
+	return registerFunction(zFuncName, &FunctionImpl{NArgs: nArg, Scalar: xFunc, Deterministic: false})
 }
 
 // MustRegisterScalarFunction is like RegisterScalarFunction but panics on
@@ -1532,6 +1677,9 @@ func MustRegisterScalarFunction(
 	nArg int32,
 	xFunc func(ctx *FunctionContext, args []driver.Value) (driver.Value, error),
 ) {
+	if dmesgs {
+		dmesg("zFuncName %q, nArg %v, xFunc %p", zFuncName, nArg, xFunc)
+	}
 	if err := RegisterScalarFunction(zFuncName, nArg, xFunc); err != nil {
 		panic(err)
 	}
@@ -1544,6 +1692,9 @@ func MustRegisterDeterministicScalarFunction(
 	nArg int32,
 	xFunc func(ctx *FunctionContext, args []driver.Value) (driver.Value, error),
 ) {
+	if dmesgs {
+		dmesg("zFuncName %q, nArg %v, xFunc %p", zFuncName, nArg, xFunc)
+	}
 	if err := RegisterDeterministicScalarFunction(zFuncName, nArg, xFunc); err != nil {
 		panic(err)
 	}
@@ -1560,15 +1711,18 @@ func RegisterDeterministicScalarFunction(
 	zFuncName string,
 	nArg int32,
 	xFunc func(ctx *FunctionContext, args []driver.Value) (driver.Value, error),
-) error {
-	return registerScalarFunction(zFuncName, nArg, sqlite3.SQLITE_UTF8|sqlite3.SQLITE_DETERMINISTIC, xFunc)
+) (err error) {
+	if dmesgs {
+		defer func() {
+			dmesg("zFuncName %q, nArg %v, xFunc %p: err %v", zFuncName, nArg, xFunc, err)
+		}()
+	}
+	return registerFunction(zFuncName, &FunctionImpl{NArgs: nArg, Scalar: xFunc, Deterministic: true})
 }
 
-func registerScalarFunction(
+func registerFunction(
 	zFuncName string,
-	nArg int32,
-	eTextRep int32,
-	xFunc func(ctx *FunctionContext, args []driver.Value) (driver.Value, error),
+	impl *FunctionImpl,
 ) error {
 
 	if _, ok := d.udfs[zFuncName]; ok {
@@ -1581,91 +1735,334 @@ func registerScalarFunction(
 		return err
 	}
 
+	var textrep int32 = sqlite3.SQLITE_UTF8
+
+	if impl.Deterministic {
+		textrep |= sqlite3.SQLITE_DETERMINISTIC
+	}
+
 	udf := &userDefinedFunction{
 		zFuncName: name,
-		nArg:      nArg,
-		eTextRep:  eTextRep,
-		xFunc: func(tls *libc.TLS, ctx uintptr, argc int32, argv uintptr) {
-			setErrorResult := func(res error) {
-				errmsg, cerr := libc.CString(res.Error())
-				if cerr != nil {
-					panic(cerr)
-				}
-				defer libc.Xfree(tls, errmsg)
-				sqlite3.Xsqlite3_result_error(tls, ctx, errmsg, -1)
-				sqlite3.Xsqlite3_result_error_code(tls, ctx, sqlite3.SQLITE_ERROR)
-			}
-
-			args := make([]driver.Value, argc)
-			for i := int32(0); i < argc; i++ {
-				valPtr := *(*uintptr)(unsafe.Pointer(argv + uintptr(i)*sqliteValPtrSize))
-
-				switch valType := sqlite3.Xsqlite3_value_type(tls, valPtr); valType {
-				case sqlite3.SQLITE_TEXT:
-					args[i] = libc.GoString(sqlite3.Xsqlite3_value_text(tls, valPtr))
-				case sqlite3.SQLITE_INTEGER:
-					args[i] = sqlite3.Xsqlite3_value_int64(tls, valPtr)
-				case sqlite3.SQLITE_FLOAT:
-					args[i] = sqlite3.Xsqlite3_value_double(tls, valPtr)
-				case sqlite3.SQLITE_NULL:
-					args[i] = nil
-				case sqlite3.SQLITE_BLOB:
-					size := sqlite3.Xsqlite3_value_bytes(tls, valPtr)
-					blobPtr := sqlite3.Xsqlite3_value_blob(tls, valPtr)
-					v := make([]byte, size)
-					copy(v, (*libc.RawMem)(unsafe.Pointer(blobPtr))[:size:size])
-					args[i] = v
-				default:
-					panic(fmt.Sprintf("unexpected argument type %q passed by sqlite", valType))
-				}
-			}
-
-			res, err := xFunc(&FunctionContext{}, args)
-			if err != nil {
-				setErrorResult(err)
-				return
-			}
-
-			switch resTyped := res.(type) {
-			case nil:
-				sqlite3.Xsqlite3_result_null(tls, ctx)
-			case int64:
-				sqlite3.Xsqlite3_result_int64(tls, ctx, resTyped)
-			case float64:
-				sqlite3.Xsqlite3_result_double(tls, ctx, resTyped)
-			case bool:
-				sqlite3.Xsqlite3_result_int(tls, ctx, libc.Bool32(resTyped))
-			case time.Time:
-				sqlite3.Xsqlite3_result_int64(tls, ctx, resTyped.Unix())
-			case string:
-				size := int32(len(resTyped))
-				cstr, err := libc.CString(resTyped)
-				if err != nil {
-					panic(err)
-				}
-				defer libc.Xfree(tls, cstr)
-				sqlite3.Xsqlite3_result_text(tls, ctx, cstr, size, sqlite3.SQLITE_TRANSIENT)
-			case []byte:
-				size := int32(len(resTyped))
-				if size == 0 {
-					sqlite3.Xsqlite3_result_zeroblob(tls, ctx, 0)
-					return
-				}
-				p := libc.Xmalloc(tls, types.Size_t(size))
-				if p == 0 {
-					panic(fmt.Sprintf("unable to allocate space for blob: %d", size))
-				}
-				defer libc.Xfree(tls, p)
-				copy((*libc.RawMem)(unsafe.Pointer(p))[:size:size], resTyped)
-
-				sqlite3.Xsqlite3_result_blob(tls, ctx, p, size, sqlite3.SQLITE_TRANSIENT)
-			default:
-				setErrorResult(fmt.Errorf("function did not return a valid driver.Value: %T", resTyped))
-				return
-			}
-		},
+		nArg:      impl.NArgs,
+		eTextRep:  textrep,
 	}
+
+	if impl.Scalar != nil {
+		xFuncs.mu.Lock()
+		id := xFuncs.ids.next()
+		xFuncs.m[id] = impl.Scalar
+		xFuncs.mu.Unlock()
+
+		udf.scalar = true
+		udf.pApp = id
+	} else {
+		xAggregateFactories.mu.Lock()
+		id := xAggregateFactories.ids.next()
+		xAggregateFactories.m[id] = impl.MakeAggregate
+		xAggregateFactories.mu.Unlock()
+
+		udf.pApp = id
+	}
+
 	d.udfs[zFuncName] = udf
 
 	return nil
 }
+
+func origin(skip int) string {
+	pc, fn, fl, _ := runtime.Caller(skip)
+	f := runtime.FuncForPC(pc)
+	var fns string
+	if f != nil {
+		fns = f.Name()
+		if x := strings.LastIndex(fns, "."); x > 0 {
+			fns = fns[x+1:]
+		}
+	}
+	return fmt.Sprintf("%s:%d:%s", fn, fl, fns)
+}
+
+func errorResultFunction(tls *libc.TLS, ctx uintptr) func(error) {
+	return func(res error) {
+		errmsg, cerr := libc.CString(res.Error())
+		if cerr != nil {
+			panic(cerr)
+		}
+		defer libc.Xfree(tls, errmsg)
+		sqlite3.Xsqlite3_result_error(tls, ctx, errmsg, -1)
+		sqlite3.Xsqlite3_result_error_code(tls, ctx, sqlite3.SQLITE_ERROR)
+	}
+}
+
+func functionArgs(tls *libc.TLS, argc int32, argv uintptr) []driver.Value {
+	args := make([]driver.Value, argc)
+	for i := int32(0); i < argc; i++ {
+		valPtr := *(*uintptr)(unsafe.Pointer(argv + uintptr(i)*sqliteValPtrSize))
+
+		switch valType := sqlite3.Xsqlite3_value_type(tls, valPtr); valType {
+		case sqlite3.SQLITE_TEXT:
+			args[i] = libc.GoString(sqlite3.Xsqlite3_value_text(tls, valPtr))
+		case sqlite3.SQLITE_INTEGER:
+			args[i] = sqlite3.Xsqlite3_value_int64(tls, valPtr)
+		case sqlite3.SQLITE_FLOAT:
+			args[i] = sqlite3.Xsqlite3_value_double(tls, valPtr)
+		case sqlite3.SQLITE_NULL:
+			args[i] = nil
+		case sqlite3.SQLITE_BLOB:
+			size := sqlite3.Xsqlite3_value_bytes(tls, valPtr)
+			blobPtr := sqlite3.Xsqlite3_value_blob(tls, valPtr)
+			v := make([]byte, size)
+			copy(v, (*libc.RawMem)(unsafe.Pointer(blobPtr))[:size:size])
+			args[i] = v
+		default:
+			panic(fmt.Sprintf("unexpected argument type %q passed by sqlite", valType))
+		}
+	}
+
+	return args
+}
+
+func functionReturnValue(tls *libc.TLS, ctx uintptr, res driver.Value) error {
+	switch resTyped := res.(type) {
+	case nil:
+		sqlite3.Xsqlite3_result_null(tls, ctx)
+	case int64:
+		sqlite3.Xsqlite3_result_int64(tls, ctx, resTyped)
+	case float64:
+		sqlite3.Xsqlite3_result_double(tls, ctx, resTyped)
+	case bool:
+		sqlite3.Xsqlite3_result_int(tls, ctx, libc.Bool32(resTyped))
+	case time.Time:
+		sqlite3.Xsqlite3_result_int64(tls, ctx, resTyped.Unix())
+	case string:
+		size := int32(len(resTyped))
+		cstr, err := libc.CString(resTyped)
+		if err != nil {
+			panic(err)
+		}
+		defer libc.Xfree(tls, cstr)
+		sqlite3.Xsqlite3_result_text(tls, ctx, cstr, size, sqlite3.SQLITE_TRANSIENT)
+	case []byte:
+		size := int32(len(resTyped))
+		if size == 0 {
+			sqlite3.Xsqlite3_result_zeroblob(tls, ctx, 0)
+			return nil
+		}
+		p := libc.Xmalloc(tls, types.Size_t(size))
+		if p == 0 {
+			panic(fmt.Sprintf("unable to allocate space for blob: %d", size))
+		}
+		defer libc.Xfree(tls, p)
+		copy((*libc.RawMem)(unsafe.Pointer(p))[:size:size], resTyped)
+
+		sqlite3.Xsqlite3_result_blob(tls, ctx, p, size, sqlite3.SQLITE_TRANSIENT)
+	default:
+		return fmt.Errorf("function did not return a valid driver.Value: %T", resTyped)
+	}
+
+	return nil
+}
+
+// The below is all taken from zombiezen.com/go/sqlite. Aggregate functions need
+// to maintain state (for instance, the count of values seen so far). We give
+// each aggregate function an ID, generated by idGen, and put that in the pApp
+// argument to sqlite3_create_function. We track this on the Go side in
+// xAggregateFactories.
+//
+// When (if) the function is called is called by a query, we call the
+// MakeAggregate factory function to set it up, and track that in
+// xAggregateContext, retrieving it via sqlite3_aggregate_context.
+//
+// We also need to ensure that, for both aggregate and scalar functions, the
+// function pointer we pass to SQLite meets certain rules on the Go side, so
+// that the pointer remains valid.
+var (
+	xFuncs = struct {
+		mu  sync.RWMutex
+		m   map[uintptr]func(*FunctionContext, []driver.Value) (driver.Value, error)
+		ids idGen
+	}{
+		m: make(map[uintptr]func(*FunctionContext, []driver.Value) (driver.Value, error)),
+	}
+
+	xAggregateFactories = struct {
+		mu  sync.RWMutex
+		m   map[uintptr]func(FunctionContext) (AggregateFunction, error)
+		ids idGen
+	}{
+		m: make(map[uintptr]func(FunctionContext) (AggregateFunction, error)),
+	}
+
+	xAggregateContext = struct {
+		mu  sync.RWMutex
+		m   map[uintptr]AggregateFunction
+		ids idGen
+	}{
+		m: make(map[uintptr]AggregateFunction),
+	}
+)
+
+type idGen struct {
+	bitset []uint64
+}
+
+func (gen *idGen) next() uintptr {
+	base := uintptr(1)
+	for i := 0; i < len(gen.bitset); i, base = i+1, base+64 {
+		b := gen.bitset[i]
+		if b != 1<<64-1 {
+			n := uintptr(bits.TrailingZeros64(^b))
+			gen.bitset[i] |= 1 << n
+			return base + n
+		}
+	}
+	gen.bitset = append(gen.bitset, 1)
+	return base
+}
+
+func (gen *idGen) reclaim(id uintptr) {
+	bit := id - 1
+	gen.bitset[bit/64] &^= 1 << (bit % 64)
+}
+
+func makeAggregate(tls *libc.TLS, ctx uintptr) (AggregateFunction, uintptr) {
+	goCtx := FunctionContext{tls: tls, ctx: ctx}
+	aggCtx := (*uintptr)(unsafe.Pointer(sqlite3.Xsqlite3_aggregate_context(tls, ctx, int32(ptrSize))))
+	setErrorResult := errorResultFunction(tls, ctx)
+	if aggCtx == nil {
+		setErrorResult(errors.New("insufficient memory for aggregate"))
+		return nil, 0
+	}
+	if *aggCtx != 0 {
+		// Already created.
+		xAggregateContext.mu.RLock()
+		f := xAggregateContext.m[*aggCtx]
+		xAggregateContext.mu.RUnlock()
+		return f, *aggCtx
+	}
+
+	factoryID := sqlite3.Xsqlite3_user_data(tls, ctx)
+	xAggregateFactories.mu.RLock()
+	factory := xAggregateFactories.m[factoryID]
+	xAggregateFactories.mu.RUnlock()
+
+	f, err := factory(goCtx)
+	if err != nil {
+		setErrorResult(err)
+		return nil, 0
+	}
+	if f == nil {
+		setErrorResult(errors.New("MakeAggregate function returned nil"))
+		return nil, 0
+	}
+
+	xAggregateContext.mu.Lock()
+	*aggCtx = xAggregateContext.ids.next()
+	xAggregateContext.m[*aggCtx] = f
+	xAggregateContext.mu.Unlock()
+	return f, *aggCtx
+}
+
+// cFuncPointer converts a function defined by a function declaration to a C pointer.
+// The result of using cFuncPointer on closures is undefined.
+func cFuncPointer[T any](f T) uintptr {
+	// This assumes the memory representation described in https://golang.org/s/go11func.
+	//
+	// cFuncPointer does its conversion by doing the following in order:
+	// 1) Create a Go struct containing a pointer to a pointer to
+	//    the function. It is assumed that the pointer to the function will be
+	//    stored in the read-only data section and thus will not move.
+	// 2) Convert the pointer to the Go struct to a pointer to uintptr through
+	//    unsafe.Pointer. This is permitted via Rule #1 of unsafe.Pointer.
+	// 3) Dereference the pointer to uintptr to obtain the function value as a
+	//    uintptr. This is safe as long as function values are passed as pointers.
+	return *(*uintptr)(unsafe.Pointer(&struct{ f T }{f}))
+}
+
+func funcTrampoline(tls *libc.TLS, ctx uintptr, argc int32, argv uintptr) {
+	id := sqlite3.Xsqlite3_user_data(tls, ctx)
+	xFuncs.mu.RLock()
+	xFunc := xFuncs.m[id]
+	xFuncs.mu.RUnlock()
+
+	setErrorResult := errorResultFunction(tls, ctx)
+	res, err := xFunc(&FunctionContext{}, functionArgs(tls, argc, argv))
+
+	if err != nil {
+		setErrorResult(err)
+		return
+	}
+
+	err = functionReturnValue(tls, ctx, res)
+	if err != nil {
+		setErrorResult(err)
+	}
+}
+
+func stepTrampoline(tls *libc.TLS, ctx uintptr, argc int32, argv uintptr) {
+	impl, _ := makeAggregate(tls, ctx)
+	if impl == nil {
+		return
+	}
+
+	setErrorResult := errorResultFunction(tls, ctx)
+	err := impl.Step(&FunctionContext{}, functionArgs(tls, argc, argv))
+	if err != nil {
+		setErrorResult(err)
+	}
+}
+
+func inverseTrampoline(tls *libc.TLS, ctx uintptr, argc int32, argv uintptr) {
+	impl, _ := makeAggregate(tls, ctx)
+	if impl == nil {
+		return
+	}
+
+	setErrorResult := errorResultFunction(tls, ctx)
+	err := impl.WindowInverse(&FunctionContext{}, functionArgs(tls, argc, argv))
+	if err != nil {
+		setErrorResult(err)
+	}
+}
+
+func valueTrampoline(tls *libc.TLS, ctx uintptr) {
+	impl, _ := makeAggregate(tls, ctx)
+	if impl == nil {
+		return
+	}
+
+	setErrorResult := errorResultFunction(tls, ctx)
+	res, err := impl.WindowValue(&FunctionContext{})
+	if err != nil {
+		setErrorResult(err)
+	} else {
+		err = functionReturnValue(tls, ctx, res)
+		if err != nil {
+			setErrorResult(err)
+		}
+	}
+}
+
+func finalTrampoline(tls *libc.TLS, ctx uintptr) {
+	impl, id := makeAggregate(tls, ctx)
+	if impl == nil {
+		return
+	}
+
+	setErrorResult := errorResultFunction(tls, ctx)
+	res, err := impl.WindowValue(&FunctionContext{})
+	if err != nil {
+		setErrorResult(err)
+	} else {
+		err = functionReturnValue(tls, ctx, res)
+		if err != nil {
+			setErrorResult(err)
+		}
+	}
+	impl.Final(&FunctionContext{})
+
+	xAggregateContext.mu.Lock()
+	defer xAggregateContext.mu.Unlock()
+	delete(xAggregateContext.m, id)
+	xAggregateContext.ids.reclaim(id)
+}