package main

// #include <stdlib.h> 
// #include "wrapper.c"
import "C"
import "unsafe"

import (
	"log"
	"time"
)

type errorString struct {
	s string
}

func (e *errorString) Error() string {
	return e.s
}

func open(file string) (int, error) {
	f := C.CString(file)
	defer C.free(unsafe.Pointer(f))
	r := int(C.my_shm_open(f, C.int(1)))
	if r == -1 {
		return 0, &errorString{"error"}
	}
	return r, nil
}

func update(shm_id int, content string) error {
	c := C.CString(content)
	defer C.free(unsafe.Pointer(c))
	r := int(C.my_shm_update(C.int(shm_id), c))
	if r == -1 {
		return &errorString{"update error"}
	}
	return nil
}

func close(shm_id int) error {
	C.my_shm_close(C.int(shm_id))
	return nil
}

func main() {
	id, err := open("/tmp")
	if err != nil {
		log.Fatal(err)
	}
	defer close(id)
	err = update(id, "hello world")
	if err != nil {
		log.Fatal(err)
	}
	time.Sleep(1e9 * 100)
}