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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2020 WireGuard LLC. All Rights Reserved.
*/
package wintun
import (
"fmt"
"sync"
"sync/atomic"
"unsafe"
)
func newLazyDLL(name string, onLoad func(d *lazyDLL)) *lazyDLL {
return &lazyDLL{Name: name, onLoad: onLoad}
}
func (d *lazyDLL) NewProc(name string) *lazyProc {
return &lazyProc{dll: d, Name: name}
}
type lazyProc struct {
Name string
mu sync.Mutex
dll *lazyDLL
addr uintptr
}
func (p *lazyProc) Find() error {
if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr))) != nil {
return nil
}
p.mu.Lock()
defer p.mu.Unlock()
if p.addr != 0 {
return nil
}
err := p.dll.Load()
if err != nil {
return fmt.Errorf("Error loading %v DLL: %w", p.dll.Name, err)
}
addr, err := p.nameToAddr()
if err != nil {
return fmt.Errorf("Error getting %v address: %w", p.Name, err)
}
atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr)), unsafe.Pointer(addr))
return nil
}
func (p *lazyProc) Addr() uintptr {
err := p.Find()
if err != nil {
panic(err)
}
return p.addr
}
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