// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package windows
import (
"sync"
"sync/atomic"
"syscall"
"unsafe"
)
// DLLError describes reasons for DLL load failures.
type DLLError struct {
Err error
ObjName string
Msg string
}
func (e *DLLError) Error() string { return e.Msg }
// Implemented in runtime/syscall_windows.goc; we provide jumps to them in our assembly file.
func loadlibrary(filename *uint16) (handle uintptr, err syscall.Errno)
func getprocaddress(handle uintptr, procname *uint8) (proc uintptr, err syscall.Errno)
// A DLL implements access to a single DLL.
type DLL struct {
Name string
Handle Handle
}
// LoadDLL loads DLL file into memory.
//
// Warning: using LoadDLL without an absolute path name is subject to
// DLL preloading attacks. To safely load a system DLL, use LazyDLL
// with System set to true, or use LoadLibraryEx directly.
func LoadDLL(name string) (dll *DLL, err error) {
namep, err := UTF16PtrFromString(name)
if err != nil {
return nil, err
}
h, e := loadlibrary(namep)
if e != 0 {
return nil, &DLLError{
Err: e,
ObjName: name,
Msg: "Failed to load " + name + ": " + e.Error(),
}
}
d := &DLL{
Name: name,
Handle: Handle(h),
}
return d, nil
}
// MustLoadDLL is like LoadDLL but panics if load operation failes.
func MustLoadDLL(name string) *DLL {
d, e := LoadDLL(name)
if e != nil {
panic(e)
}
return d
}
// FindProc searches DLL d for procedure named name and returns *Proc
// if found. It returns an error if search fails.
func (d *DLL) FindProc(name string) (proc *Proc, err error) {
namep, err := BytePtrFromString(name)
if err != nil {
return nil, err
}
a, e := getprocaddress(uintptr(d.Handle), namep)
if e != 0 {
return nil, &DLLError{
Err: e,
ObjName: name,
Msg: "Failed to find " + name + " procedure in " + d.Name + ": " + e.Error(),
}
}
p := &Proc{
Dll: d,
Name: name,
addr: a,
}
return p, nil
}
// MustFindProc is like FindProc but panics if search fails.
func (d *DLL) MustFindProc(name string) *Proc {
p, e := d.FindProc(name)
if e != nil {
panic(e)
}
return p
}
// Release unloads DLL d from memory.
func (d *DLL) Release() (err error) {
return FreeLibrary(d.Handle)
}
// A Proc implements access to a procedure inside a DLL.
type Proc struct {
Dll *DLL
Name string
addr uintptr
}
// Addr returns the address of the procedure represented by p.
// The return value can be passed to Syscall to run the procedure.
func (p *Proc) Addr() uintptr {
return p.addr
}
//go:uintptrescapes
// Call executes procedure p with arguments a. It will panic, if more than 15 arguments
// are supplied.
//
// The returned error is always non-nil, constructed from the result of GetLastError.
// Callers must inspect the primary return value to decide whether an error occurred
// (according to the semantics of the specific function being called) before consulting
// the error. The error will be guaranteed to contain windows.Errno.
func (p *Proc) Call(a ...uintptr) (r1, r2 uintptr, lastErr error) {
switch len(a) {
case 0:
return syscall.Syscall(p.Addr(), uintptr(len(a)), 0, 0, 0)
case 1:
return syscall.Syscall(p.Addr(), uintptr(len(a)), a[0], 0, 0)
case 2:
return syscall.Syscall(p.Addr(), uintptr(len(a)), a[0], a[1], 0)
case 3:
return syscall.Syscall(p.Addr(), uintptr(len(a)), a[0], a[1], a[2])
case 4:
return syscall.Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], 0, 0)
case 5:
return syscall.Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], 0)
case 6:
return syscall.Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5])
case 7:
return syscall.Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], 0, 0)
case 8:
return syscall.Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], 0)
case 9:
return syscall.Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8])
case 10:
return syscall.Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], 0, 0)
case 11:
return syscall.Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], 0)
case 12:
return syscall.Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11])
case 13:
return syscall.Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], 0, 0)
case 14:
return syscall.Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], 0)
case 15:
return syscall.Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14])
default:
panic("Call " + p.Name + " with too many arguments " + itoa(len(a)) + ".")
}
}
// A LazyDLL implements access to a single DLL.
// It will delay the load of the DLL until the first
// call to its Handle method or to one of its
// LazyProc's Addr method.
type LazyDLL struct {
Name string
// System determines whether the DLL must be loaded from the
// Windows System directory, bypassing the normal DLL search
// path.
System bool
mu sync.Mutex
dll *DLL // non nil once DLL is loaded
}
// Load loads DLL file d.Name into memory. It returns an error if fails.
// Load will not try to load DLL, if it is already loaded into memory.
func (d *LazyDLL) Load() error {
// Non-racy version of:
// if d.dll != nil {
if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&d.dll))) != nil {
return nil
}
d.mu.Lock()
defer d.mu.Unlock()
if d.dll != nil {
return nil
}
// kernel32.dll is special, since it's where LoadLibraryEx comes from.
// The kernel already special-cases its name, so it's always
// loaded from system32.
var dll *DLL
var err error
if d.Name == "kernel32.dll" {
dll, err = LoadDLL(d.Name)
} else {
dll, err = loadLibraryEx(d.Name, d.System)
}
if err != nil {
return err
}
// Non-racy version of:
// d.dll = dll
atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&d.dll)), unsafe.Pointer(dll))
return nil
}
// mustLoad is like Load but panics if search fails.
func (d *LazyDLL) mustLoad() {
e := d.Load()
if e != nil {
panic(e)
}
}
// Handle returns d's module handle.
func (d *LazyDLL) Handle() uintptr {
d.mustLoad()
return uintptr(d.dll.Handle)
}
// NewProc returns a LazyProc for accessing the named procedure in the DLL d.
func (d *LazyDLL) NewProc(name string) *LazyProc {
return &LazyProc{l: d, Name: name}
}
// NewLazyDLL creates new LazyDLL associated with DLL file.
func NewLazyDLL(name string) *LazyDLL {
return &LazyDLL{Name: name}
}
// NewLazySystemDLL is like NewLazyDLL, but will only
// search Windows System directory for the DLL if name is
// a base name (like "advapi32.dll").
func NewLazySystemDLL(name string) *LazyDLL {
return &LazyDLL{Name: name, System: true}
}
// A LazyProc implements access to a procedure inside a LazyDLL.
// It delays the lookup until the Addr method is called.
type LazyProc struct {
Name string
mu sync.Mutex
l *LazyDLL
proc *Proc
}
// Find searches DLL for procedure named p.Name. It returns
// an error if search fails. Find will not search procedure,
// if it is already found and loaded into memory.
func (p *LazyProc) Find() error {
// Non-racy version of:
// if p.proc == nil {
if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&p.proc))) == nil {
p.mu.Lock()
defer p.mu.Unlock()
if p.proc == nil {
e := p.l.Load()
if e != nil {
return e
}
proc, e := p.l.dll.FindProc(p.Name)
if e != nil {
return e
}
// Non-racy version of:
// p.proc = proc
atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&p.proc)), unsafe.Pointer(proc))
}
}
return nil
}
// mustFind is like Find but panics if search fails.
func (p *LazyProc) mustFind() {
e := p.Find()
if e != nil {
panic(e)
}
}
// Addr returns the address of the procedure represented by p.
// The return value can be passed to Syscall to run the procedure.
// It will panic if the procedure cannot be found.
func (p *LazyProc) Addr() uintptr {
p.mustFind()
return p.proc.Addr()
}
//go:uintptrescapes
// Call executes procedure p with arguments a. It will panic, if more than 15 arguments
// are supplied. It will also panic if the procedure cannot be found.
//
// The returned error is always non-nil, constructed from the result of GetLastError.
// Callers must inspect the primary return value to decide whether an error occurred
// (according to the semantics of the specific function being called) before consulting
// the error. The error will be guaranteed to contain windows.Errno.
func (p *LazyProc) Call(a ...uintptr) (r1, r2 uintptr, lastErr error) {
p.mustFind()
return p.proc.Call(a...)
}
var canDoSearchSystem32Once struct {
sync.Once
v bool
}
func initCanDoSearchSystem32() {
// https://msdn.microsoft.com/en-us/library/ms684179(v=vs.85).aspx says:
// "Windows 7, Windows Server 2008 R2, Windows Vista, and Windows
// Server 2008: The LOAD_LIBRARY_SEARCH_* flags are available on
// systems that have KB2533623 installed. To determine whether the
// flags are available, use GetProcAddress to get the address of the
// AddDllDirectory, RemoveDllDirectory, or SetDefaultDllDirectories
// function. If GetProcAddress succeeds, the LOAD_LIBRARY_SEARCH_*
// flags can be used with LoadLibraryEx."
canDoSearchSystem32Once.v = (modkernel32.NewProc("AddDllDirectory").Find() == nil)
}
func canDoSearchSystem32() bool {
canDoSearchSystem32Once.Do(initCanDoSearchSystem32)
return canDoSearchSystem32Once.v
}
func isBaseName(name string) bool {
for _, c := range name {
if c == ':' || c == '/' || c == '\\' {
return false
}
}
return true
}
// loadLibraryEx wraps the Windows LoadLibraryEx function.
//
// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms684179(v=vs.85).aspx
//
// If name is not an absolute path, LoadLibraryEx searches for the DLL
// in a variety of automatic locations unless constrained by flags.
// See: https://msdn.microsoft.com/en-us/library/ff919712%28VS.85%29.aspx
func loadLibraryEx(name string, system bool) (*DLL, error) {
loadDLL := name
var flags uintptr
if system {
if canDoSearchSystem32() {
const LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800
flags = LOAD_LIBRARY_SEARCH_SYSTEM32
} else if isBaseName(name) {
// WindowsXP or unpatched Windows machine
// trying to load "foo.dll" out of the system
// folder, but LoadLibraryEx doesn't support
// that yet on their system, so emulate it.
windir, _ := Getenv("WINDIR") // old var; apparently works on XP
if windir == "" {
return nil, errString("%WINDIR% not defined")
}
loadDLL = windir + "\\System32\\" + name
}
}
h, err := LoadLibraryEx(loadDLL, 0, flags)
if err != nil {
return nil, err
}
return &DLL{Name: name, Handle: h}, nil
}
type errString string
func (s errString) Error() string { return string(s) }
