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package pointer
// #include <stdlib.h>
import "C"
import (
"sync"
"unsafe"
)
var (
mutex sync.Mutex
store = map[unsafe.Pointer]interface{}{}
)
func Save(v interface{}) unsafe.Pointer {
if v == nil {
return nil
}
// Generate real fake C pointer.
// This pointer will not store any data, but will bi used for indexing purposes.
// Since Go doest allow to cast dangling pointer to unsafe.Pointer, we do rally allocate one byte.
// Why we need indexing, because Go doest allow C code to store pointers to Go data.
var ptr unsafe.Pointer = C.malloc(C.size_t(1))
if ptr == nil {
panic("can't allocate 'cgo-pointer hack index pointer': ptr == nil")
}
mutex.Lock()
store[ptr] = v
mutex.Unlock()
return ptr
}
func Restore(ptr unsafe.Pointer) (v interface{}) {
if ptr == nil {
return nil
}
mutex.Lock()
v = store[ptr]
mutex.Unlock()
return
}
func Unref(ptr unsafe.Pointer) {
if ptr == nil {
return
}
mutex.Lock()
delete(store, ptr)
mutex.Unlock()
C.free(ptr)
}
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