sqlite3_opt_serialize: fix 'go vet' warnings

sqlite3_opt_serialize.go

@@ -3,21 +3,19 @@
 
 package sqlite3
 
-/*
-#ifndef USE_LIBSQLITE3
-#include <sqlite3-binding.h>
-#else
-#include <sqlite3.h>
-#endif
-#include <stdlib.h>
-#include <stdint.h>
-*/
+// #ifndef USE_LIBSQLITE3
+// #include <sqlite3-binding.h>
+// #else
+// #include <sqlite3.h>
+// #endif /* USE_LIBSQLITE3 */
+// #include <stdlib.h>
+// #include <stdint.h>
 import "C"
 
 import (
+	"errors"
 	"fmt"
 	"math"
-	"reflect"
 	"unsafe"
 )
 
@@ -28,29 +26,23 @@ func (c *SQLiteConn) Serialize(schema string) ([]byte, error) {
 	if schema == "" {
 		schema = "main"
 	}
-	var zSchema *C.char
-	zSchema = C.CString(schema)
+	zSchema := C.CString(schema)
 	defer C.free(unsafe.Pointer(zSchema))
 
 	var sz C.sqlite3_int64
 	ptr := C.sqlite3_serialize(c.db, zSchema, &sz, 0)
 	if ptr == nil {
-		return nil, fmt.Errorf("serialize failed")
+		return nil, errors.New(`sqlite3: failed to serialize: "` + schema + `"`)
 	}
 	defer C.sqlite3_free(unsafe.Pointer(ptr))
 
-	if sz > C.sqlite3_int64(math.MaxInt) {
-		return nil, fmt.Errorf("serialized database is too large (%d bytes)", sz)
+	if int64(sz) > math.MaxInt {
+		return nil, fmt.Errorf("sqlite3: serialized database is too large (%d bytes)", int64(sz))
 	}
 
-	cBuf := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
-		Data: uintptr(unsafe.Pointer(ptr)),
-		Len:  int(sz),
-		Cap:  int(sz),
-	}))
-
-	res := make([]byte, int(sz))
-	copy(res, cBuf)
+	buf := unsafe.Slice((*byte)(unsafe.Pointer(ptr)), sz)
+	res := make([]byte, len(buf))
+	copy(res, buf)
 	return res, nil
 }
 
@@ -62,19 +54,13 @@ func (c *SQLiteConn) Deserialize(b []byte, schema string) error {
 	if schema == "" {
 		schema = "main"
 	}
-	var zSchema *C.char
-	zSchema = C.CString(schema)
+	zSchema := C.CString(schema)
 	defer C.free(unsafe.Pointer(zSchema))
 
-	tmpBuf := (*C.uchar)(C.sqlite3_malloc64(C.sqlite3_uint64(len(b))))
-	cBuf := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
-		Data: uintptr(unsafe.Pointer(tmpBuf)),
-		Len:  len(b),
-		Cap:  len(b),
-	}))
-	copy(cBuf, b)
-
-	rc := C.sqlite3_deserialize(c.db, zSchema, tmpBuf, C.sqlite3_int64(len(b)),
+	tmp := (*C.uchar)(C.sqlite3_malloc64(C.sqlite3_uint64(len(b))))
+	buf := unsafe.Slice((*byte)(unsafe.Pointer(tmp)), len(b))
+	copy(buf, b)
+	rc := C.sqlite3_deserialize(c.db, zSchema, tmp, C.sqlite3_int64(len(b)),
 		C.sqlite3_int64(len(b)), C.SQLITE_DESERIALIZE_FREEONCLOSE)
 	if rc != C.SQLITE_OK {
 		return fmt.Errorf("deserialize failed with return %v", rc)