diff options
Diffstat (limited to 'libgo/go/runtime/cgo/handle.go')
| -rw-r--r-- | libgo/go/runtime/cgo/handle.go | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/libgo/go/runtime/cgo/handle.go b/libgo/go/runtime/cgo/handle.go index 720acca..d711900 100644 --- a/libgo/go/runtime/cgo/handle.go +++ b/libgo/go/runtime/cgo/handle.go @@ -59,6 +59,41 @@ import ( // void myprint(uintptr_t handle) { // MyGoPrint(handle); // } +// +// Some C functions accept a void* argument that points to an arbitrary +// data value supplied by the caller. It is not safe to coerce a cgo.Handle +// (an integer) to a Go unsafe.Pointer, but instead we can pass the address +// of the cgo.Handle to the void* parameter, as in this variant of the +// previous example: +// +// package main +// +// /* +// extern void MyGoPrint(void *context); +// static inline void myprint(void *context) { +// MyGoPrint(context); +// } +// */ +// import "C" +// import ( +// "runtime/cgo" +// "unsafe" +// ) +// +// //export MyGoPrint +// func MyGoPrint(context unsafe.Pointer) { +// h := *(*cgo.Handle)(context) +// val := h.Value().(string) +// println(val) +// h.Delete() +// } +// +// func main() { +// val := "hello Go" +// h := cgo.NewHandle(val) +// C.myprint(unsafe.Pointer(&h)) +// // Output: hello Go +// } type Handle uintptr // NewHandle returns a handle for a given value. @@ -70,7 +105,7 @@ type Handle uintptr // // The intended use is to pass the returned handle to C code, which // passes it back to Go, which calls Value. -func NewHandle(v interface{}) Handle { +func NewHandle(v any) Handle { h := atomic.AddUintptr(&handleIdx, 1) if h == 0 { panic("runtime/cgo: ran out of handle space") @@ -83,7 +118,7 @@ func NewHandle(v interface{}) Handle { // Value returns the associated Go value for a valid handle. // // The method panics if the handle is invalid. -func (h Handle) Value() interface{} { +func (h Handle) Value() any { v, ok := handles.Load(uintptr(h)) if !ok { panic("runtime/cgo: misuse of an invalid Handle") |