contract/callback.go
// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package contract
// You can't export a Go function to C and have definitions in the C
// preamble in the same file, so we have to have callbackTrampoline in
// its own file. Because we need a separate file anyway, the support
// code for SQLite custom functions is in here.
/*
#include <stdlib.h>
#include <sqlite3-binding.h>
void _sqlite3_result_text(sqlite3_context* ctx, const char* s);
void _sqlite3_result_blob(sqlite3_context* ctx, const void* b, int l);
*/
import "C"
import (
"errors"
"fmt"
"math"
"reflect"
"sync"
"unsafe"
)
//export callbackTrampoline
func callbackTrampoline(ctx *C.sqlite3_context, argc int, argv **C.sqlite3_value) {
args := (*[(math.MaxInt32 - 1) / unsafe.Sizeof((*C.sqlite3_value)(nil))]*C.sqlite3_value)(unsafe.Pointer(argv))[:argc:argc]
fi := lookupHandle(uintptr(C.sqlite3_user_data(ctx))).(*functionInfo)
fi.Call(ctx, args)
}
//export stepTrampoline
func stepTrampoline(ctx *C.sqlite3_context, argc C.int, argv **C.sqlite3_value) {
args := (*[(math.MaxInt32 - 1) / unsafe.Sizeof((*C.sqlite3_value)(nil))]*C.sqlite3_value)(unsafe.Pointer(argv))[:int(argc):int(argc)]
ai := lookupHandle(uintptr(C.sqlite3_user_data(ctx))).(*aggInfo)
ai.Step(ctx, args)
}
//export doneTrampoline
func doneTrampoline(ctx *C.sqlite3_context) {
handle := uintptr(C.sqlite3_user_data(ctx))
ai := lookupHandle(handle).(*aggInfo)
ai.Done(ctx)
}
//export compareTrampoline
func compareTrampoline(handlePtr uintptr, la C.int, a *C.char, lb C.int, b *C.char) C.int {
cmp := lookupHandle(handlePtr).(func(string, string) int)
return C.int(cmp(C.GoStringN(a, la), C.GoStringN(b, lb)))
}
//export commitHookTrampoline
func commitHookTrampoline(handle uintptr) int {
callback := lookupHandle(handle).(func() int)
return callback()
}
//export rollbackHookTrampoline
func rollbackHookTrampoline(handle uintptr) {
callback := lookupHandle(handle).(func())
callback()
}
//export updateHookTrampoline
func updateHookTrampoline(handle uintptr, op int, db *C.char, table *C.char, rowid int64) {
callback := lookupHandle(handle).(func(int, string, string, int64))
callback(op, C.GoString(db), C.GoString(table), rowid)
}
//export authorizerTrampoline
func authorizerTrampoline(handle uintptr, op int, arg1 *C.char, arg2 *C.char, arg3 *C.char) int {
callback := lookupHandle(handle).(func(int, string, string, string) int)
return callback(op, C.GoString(arg1), C.GoString(arg2), C.GoString(arg3))
}
// Use handles to avoid passing Go pointers to C.
type handleVal struct {
db *SQLiteConn
val interface{}
}
var handleLock sync.Mutex
var handleVals = make(map[uintptr]handleVal)
var handleIndex uintptr = 100
func newHandle(db *SQLiteConn, v interface{}) uintptr {
handleLock.Lock()
defer handleLock.Unlock()
i := handleIndex
handleIndex++
handleVals[i] = handleVal{db, v}
return i
}
func lookupHandle(handle uintptr) interface{} {
handleLock.Lock()
defer handleLock.Unlock()
r, ok := handleVals[handle]
if !ok {
if handle >= 100 && handle < handleIndex {
panic("deleted handle")
} else {
panic("invalid handle")
}
}
return r.val
}
func deleteHandles(db *SQLiteConn) {
handleLock.Lock()
defer handleLock.Unlock()
for handle, val := range handleVals {
if val.db == db {
delete(handleVals, handle)
}
}
}
// This is only here so that tests can refer to it.
type callbackArgRaw C.sqlite3_value
type callbackArgConverter func(*C.sqlite3_value) (reflect.Value, error)
type callbackArgCast struct {
f callbackArgConverter
typ reflect.Type
}
func (c callbackArgCast) Run(v *C.sqlite3_value) (reflect.Value, error) {
val, err := c.f(v)
if err != nil {
return reflect.Value{}, err
}
if !val.Type().ConvertibleTo(c.typ) {
return reflect.Value{}, fmt.Errorf("cannot convert %s to %s", val.Type(), c.typ)
}
return val.Convert(c.typ), nil
}
func callbackArgInt64(v *C.sqlite3_value) (reflect.Value, error) {
if C.sqlite3_value_type(v) != C.SQLITE_INTEGER {
return reflect.Value{}, fmt.Errorf("argument must be an INTEGER")
}
return reflect.ValueOf(int64(C.sqlite3_value_int64(v))), nil
}
func callbackArgBool(v *C.sqlite3_value) (reflect.Value, error) {
if C.sqlite3_value_type(v) != C.SQLITE_INTEGER {
return reflect.Value{}, fmt.Errorf("argument must be an INTEGER")
}
i := int64(C.sqlite3_value_int64(v))
val := false
if i != 0 {
val = true
}
return reflect.ValueOf(val), nil
}
func callbackArgFloat64(v *C.sqlite3_value) (reflect.Value, error) {
if C.sqlite3_value_type(v) != C.SQLITE_FLOAT {
return reflect.Value{}, fmt.Errorf("argument must be a FLOAT")
}
return reflect.ValueOf(float64(C.sqlite3_value_double(v))), nil
}
func callbackArgBytes(v *C.sqlite3_value) (reflect.Value, error) {
switch C.sqlite3_value_type(v) {
case C.SQLITE_BLOB:
l := C.sqlite3_value_bytes(v)
p := C.sqlite3_value_blob(v)
return reflect.ValueOf(C.GoBytes(p, l)), nil
case C.SQLITE_TEXT:
l := C.sqlite3_value_bytes(v)
c := unsafe.Pointer(C.sqlite3_value_text(v))
return reflect.ValueOf(C.GoBytes(c, l)), nil
default:
return reflect.Value{}, fmt.Errorf("argument must be BLOB or TEXT")
}
}
func callbackArgString(v *C.sqlite3_value) (reflect.Value, error) {
switch C.sqlite3_value_type(v) {
case C.SQLITE_BLOB:
l := C.sqlite3_value_bytes(v)
p := (*C.char)(C.sqlite3_value_blob(v))
return reflect.ValueOf(C.GoStringN(p, l)), nil
case C.SQLITE_TEXT:
c := (*C.char)(unsafe.Pointer(C.sqlite3_value_text(v)))
return reflect.ValueOf(C.GoString(c)), nil
default:
return reflect.Value{}, fmt.Errorf("argument must be BLOB or TEXT")
}
}
func callbackArgGeneric(v *C.sqlite3_value) (reflect.Value, error) {
switch C.sqlite3_value_type(v) {
case C.SQLITE_INTEGER:
return callbackArgInt64(v)
case C.SQLITE_FLOAT:
return callbackArgFloat64(v)
case C.SQLITE_TEXT:
return callbackArgString(v)
case C.SQLITE_BLOB:
return callbackArgBytes(v)
case C.SQLITE_NULL:
// Interpret NULL as a nil byte slice.
var ret []byte
return reflect.ValueOf(ret), nil
default:
panic("unreachable")
}
}
func callbackArg(typ reflect.Type) (callbackArgConverter, error) {
switch typ.Kind() {
case reflect.Interface:
if typ.NumMethod() != 0 {
return nil, errors.New("the only supported interface type is interface{}")
}
return callbackArgGeneric, nil
case reflect.Slice:
if typ.Elem().Kind() != reflect.Uint8 {
return nil, errors.New("the only supported slice type is []byte")
}
return callbackArgBytes, nil
case reflect.String:
return callbackArgString, nil
case reflect.Bool:
return callbackArgBool, nil
case reflect.Int64:
return callbackArgInt64, nil
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
c := callbackArgCast{callbackArgInt64, typ}
return c.Run, nil
case reflect.Float64:
return callbackArgFloat64, nil
case reflect.Float32:
c := callbackArgCast{callbackArgFloat64, typ}
return c.Run, nil
default:
return nil, fmt.Errorf("don't know how to convert to %s", typ)
}
}
func callbackConvertArgs(argv []*C.sqlite3_value, converters []callbackArgConverter, variadic callbackArgConverter) ([]reflect.Value, error) {
var args []reflect.Value
if len(argv) < len(converters) {
return nil, fmt.Errorf("function requires at least %d arguments", len(converters))
}
for i, arg := range argv[:len(converters)] {
v, err := converters[i](arg)
if err != nil {
return nil, err
}
args = append(args, v)
}
if variadic != nil {
for _, arg := range argv[len(converters):] {
v, err := variadic(arg)
if err != nil {
return nil, err
}
args = append(args, v)
}
}
return args, nil
}
type callbackRetConverter func(*C.sqlite3_context, reflect.Value) error
func callbackRetInteger(ctx *C.sqlite3_context, v reflect.Value) error {
switch v.Type().Kind() {
case reflect.Int64:
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
v = v.Convert(reflect.TypeOf(int64(0)))
case reflect.Bool:
b := v.Interface().(bool)
if b {
v = reflect.ValueOf(int64(1))
} else {
v = reflect.ValueOf(int64(0))
}
default:
return fmt.Errorf("cannot convert %s to INTEGER", v.Type())
}
C.sqlite3_result_int64(ctx, C.sqlite3_int64(v.Interface().(int64)))
return nil
}
func callbackRetFloat(ctx *C.sqlite3_context, v reflect.Value) error {
switch v.Type().Kind() {
case reflect.Float64:
case reflect.Float32:
v = v.Convert(reflect.TypeOf(float64(0)))
default:
return fmt.Errorf("cannot convert %s to FLOAT", v.Type())
}
C.sqlite3_result_double(ctx, C.double(v.Interface().(float64)))
return nil
}
func callbackRetBlob(ctx *C.sqlite3_context, v reflect.Value) error {
if v.Type().Kind() != reflect.Slice || v.Type().Elem().Kind() != reflect.Uint8 {
return fmt.Errorf("cannot convert %s to BLOB", v.Type())
}
i := v.Interface()
if i == nil || len(i.([]byte)) == 0 {
C.sqlite3_result_null(ctx)
} else {
bs := i.([]byte)
C._sqlite3_result_blob(ctx, unsafe.Pointer(&bs[0]), C.int(len(bs)))
}
return nil
}
func callbackRetText(ctx *C.sqlite3_context, v reflect.Value) error {
if v.Type().Kind() != reflect.String {
return fmt.Errorf("cannot convert %s to TEXT", v.Type())
}
C._sqlite3_result_text(ctx, C.CString(v.Interface().(string)))
return nil
}
func callbackRetNil(ctx *C.sqlite3_context, v reflect.Value) error {
return nil
}
func callbackRet(typ reflect.Type) (callbackRetConverter, error) {
switch typ.Kind() {
case reflect.Interface:
errorInterface := reflect.TypeOf((*error)(nil)).Elem()
if typ.Implements(errorInterface) {
return callbackRetNil, nil
}
fallthrough
case reflect.Slice:
if typ.Elem().Kind() != reflect.Uint8 {
return nil, errors.New("the only supported slice type is []byte")
}
return callbackRetBlob, nil
case reflect.String:
return callbackRetText, nil
case reflect.Bool, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
return callbackRetInteger, nil
case reflect.Float32, reflect.Float64:
return callbackRetFloat, nil
default:
return nil, fmt.Errorf("don't know how to convert to %s", typ)
}
}
func callbackError(ctx *C.sqlite3_context, err error) {
cstr := C.CString(err.Error())
defer C.free(unsafe.Pointer(cstr))
C.sqlite3_result_error(ctx, cstr, -1)
}
// Test support code. Tests are not allowed to import "C", so we can't
// declare any functions that use C.sqlite3_value.
func callbackSyntheticForTests(v reflect.Value, err error) callbackArgConverter {
return func(*C.sqlite3_value) (reflect.Value, error) {
return v, err
}
}