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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2020 WireGuard LLC. All Rights Reserved.
*/
package wintun
import (
"fmt"
"sync"
"sync/atomic"
"unsafe"
"golang.org/x/sys/windows"
"golang.zx2c4.com/wireguard/tun/wintun/memmod"
"golang.zx2c4.com/wireguard/tun/wintun/resource"
)
type lazyDLL struct {
Name string
mu sync.Mutex
module *memmod.Module
}
func newLazyDLL(name string) *lazyDLL {
return &lazyDLL{Name: name}
}
func (d *lazyDLL) Load() error {
if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&d.module))) != nil {
return nil
}
d.mu.Lock()
defer d.mu.Unlock()
if d.module != nil {
return nil
}
const ourModule windows.Handle = 0
resInfo, err := resource.FindByName(ourModule, d.Name, resource.RT_RCDATA)
if err != nil {
return fmt.Errorf("Unable to find \"%v\" RCDATA resource: %v", d.Name, err)
}
data, err := resource.Load(ourModule, resInfo)
if err != nil {
return fmt.Errorf("Unable to load resource: %v", err)
}
module, err := memmod.LoadLibrary(data)
if err != nil {
return fmt.Errorf("Unable to load library: %v", err)
}
atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&d.module)), unsafe.Pointer(module))
return nil
}
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: %v", p.dll.Name, err)
}
addr, err := p.dll.module.ProcAddressByName(p.Name)
if err != nil {
return fmt.Errorf("Error getting %v address: %v", 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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