// Copyright 2010 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 runtime_test

import (
	"bytes"
	"fmt"
	"internal/abi"
	"internal/syscall/windows/sysdll"
	"internal/testenv"
	"io"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"strconv"
	"strings"
	"syscall"
	"testing"
	"unsafe"
)

type DLL struct {
	*syscall.DLL
	t *testing.T
}

func GetDLL(t *testing.T, name string) *DLL {
	d, e := syscall.LoadDLL(name)
	if e != nil {
		t.Fatal(e)
	}
	return &DLL{DLL: d, t: t}
}

func (d *DLL) Proc(name string) *syscall.Proc {
	p, e := d.FindProc(name)
	if e != nil {
		d.t.Fatal(e)
	}
	return p
}

func TestStdCall(t *testing.T) {
	type Rect struct {
		left, top, right, bottom int32
	}
	res := Rect{}
	expected := Rect{1, 1, 40, 60}
	a, _, _ := GetDLL(t, "user32.dll").Proc("UnionRect").Call(
		uintptr(unsafe.Pointer(&res)),
		uintptr(unsafe.Pointer(&Rect{10, 1, 14, 60})),
		uintptr(unsafe.Pointer(&Rect{1, 2, 40, 50})))
	if a != 1 || res.left != expected.left ||
		res.top != expected.top ||
		res.right != expected.right ||
		res.bottom != expected.bottom {
		t.Error("stdcall USER32.UnionRect returns", a, "res=", res)
	}
}

func Test64BitReturnStdCall(t *testing.T) {

	const (
		VER_BUILDNUMBER      = 0x0000004
		VER_MAJORVERSION     = 0x0000002
		VER_MINORVERSION     = 0x0000001
		VER_PLATFORMID       = 0x0000008
		VER_PRODUCT_TYPE     = 0x0000080
		VER_SERVICEPACKMAJOR = 0x0000020
		VER_SERVICEPACKMINOR = 0x0000010
		VER_SUITENAME        = 0x0000040

		VER_EQUAL         = 1
		VER_GREATER       = 2
		VER_GREATER_EQUAL = 3
		VER_LESS          = 4
		VER_LESS_EQUAL    = 5

		ERROR_OLD_WIN_VERSION syscall.Errno = 1150
	)

	type OSVersionInfoEx struct {
		OSVersionInfoSize uint32
		MajorVersion      uint32
		MinorVersion      uint32
		BuildNumber       uint32
		PlatformId        uint32
		CSDVersion        [128]uint16
		ServicePackMajor  uint16
		ServicePackMinor  uint16
		SuiteMask         uint16
		ProductType       byte
		Reserve           byte
	}

	d := GetDLL(t, "kernel32.dll")

	var m1, m2 uintptr
	VerSetConditionMask := d.Proc("VerSetConditionMask")
	m1, m2, _ = VerSetConditionMask.Call(m1, m2, VER_MAJORVERSION, VER_GREATER_EQUAL)
	m1, m2, _ = VerSetConditionMask.Call(m1, m2, VER_MINORVERSION, VER_GREATER_EQUAL)
	m1, m2, _ = VerSetConditionMask.Call(m1, m2, VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL)
	m1, m2, _ = VerSetConditionMask.Call(m1, m2, VER_SERVICEPACKMINOR, VER_GREATER_EQUAL)

	vi := OSVersionInfoEx{
		MajorVersion:     5,
		MinorVersion:     1,
		ServicePackMajor: 2,
		ServicePackMinor: 0,
	}
	vi.OSVersionInfoSize = uint32(unsafe.Sizeof(vi))
	r, _, e2 := d.Proc("VerifyVersionInfoW").Call(
		uintptr(unsafe.Pointer(&vi)),
		VER_MAJORVERSION|VER_MINORVERSION|VER_SERVICEPACKMAJOR|VER_SERVICEPACKMINOR,
		m1, m2)
	if r == 0 && e2 != ERROR_OLD_WIN_VERSION {
		t.Errorf("VerifyVersionInfo failed: %s", e2)
	}
}

func TestCDecl(t *testing.T) {
	var buf [50]byte
	fmtp, _ := syscall.BytePtrFromString("%d %d %d")
	a, _, _ := GetDLL(t, "user32.dll").Proc("wsprintfA").Call(
		uintptr(unsafe.Pointer(&buf[0])),
		uintptr(unsafe.Pointer(fmtp)),
		1000, 2000, 3000)
	if string(buf[:a]) != "1000 2000 3000" {
		t.Error("cdecl USER32.wsprintfA returns", a, "buf=", buf[:a])
	}
}

func TestEnumWindows(t *testing.T) {
	d := GetDLL(t, "user32.dll")
	isWindows := d.Proc("IsWindow")
	counter := 0
	cb := syscall.NewCallback(func(hwnd syscall.Handle, lparam uintptr) uintptr {
		if lparam != 888 {
			t.Error("lparam was not passed to callback")
		}
		b, _, _ := isWindows.Call(uintptr(hwnd))
		if b == 0 {
			t.Error("USER32.IsWindow returns FALSE")
		}
		counter++
		return 1 // continue enumeration
	})
	a, _, _ := d.Proc("EnumWindows").Call(cb, 888)
	if a == 0 {
		t.Error("USER32.EnumWindows returns FALSE")
	}
	if counter == 0 {
		t.Error("Callback has been never called or your have no windows")
	}
}

func callback(timeFormatString unsafe.Pointer, lparam uintptr) uintptr {
	(*(*func())(unsafe.Pointer(&lparam)))()
	return 0 // stop enumeration
}

// nestedCall calls into Windows, back into Go, and finally to f.
func nestedCall(t *testing.T, f func()) {
	c := syscall.NewCallback(callback)
	d := GetDLL(t, "kernel32.dll")
	defer d.Release()
	const LOCALE_NAME_USER_DEFAULT = 0
	d.Proc("EnumTimeFormatsEx").Call(c, LOCALE_NAME_USER_DEFAULT, 0, uintptr(*(*unsafe.Pointer)(unsafe.Pointer(&f))))
}

func TestCallback(t *testing.T) {
	var x = false
	nestedCall(t, func() { x = true })
	if !x {
		t.Fatal("nestedCall did not call func")
	}
}

func TestCallbackGC(t *testing.T) {
	nestedCall(t, runtime.GC)
}

func TestCallbackPanicLocked(t *testing.T) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	if !runtime.LockedOSThread() {
		t.Fatal("runtime.LockOSThread didn't")
	}
	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {
			t.Fatal("wrong panic:", s)
		}
		if !runtime.LockedOSThread() {
			t.Fatal("lost lock on OS thread after panic")
		}
	}()
	nestedCall(t, func() { panic("callback panic") })
	panic("nestedCall returned")
}

func TestCallbackPanic(t *testing.T) {
	// Make sure panic during callback unwinds properly.
	if runtime.LockedOSThread() {
		t.Fatal("locked OS thread on entry to TestCallbackPanic")
	}
	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {
			t.Fatal("wrong panic:", s)
		}
		if runtime.LockedOSThread() {
			t.Fatal("locked OS thread on exit from TestCallbackPanic")
		}
	}()
	nestedCall(t, func() { panic("callback panic") })
	panic("nestedCall returned")
}

func TestCallbackPanicLoop(t *testing.T) {
	// Make sure we don't blow out m->g0 stack.
	for i := 0; i < 100000; i++ {
		TestCallbackPanic(t)
	}
}

func TestBlockingCallback(t *testing.T) {
	c := make(chan int)
	go func() {
		for i := 0; i < 10; i++ {
			c <- <-c
		}
	}()
	nestedCall(t, func() {
		for i := 0; i < 10; i++ {
			c <- i
			if j := <-c; j != i {
				t.Errorf("out of sync %d != %d", j, i)
			}
		}
	})
}

func TestCallbackInAnotherThread(t *testing.T) {
	d := GetDLL(t, "kernel32.dll")

	f := func(p uintptr) uintptr {
		return p
	}
	r, _, err := d.Proc("CreateThread").Call(0, 0, syscall.NewCallback(f), 123, 0, 0)
	if r == 0 {
		t.Fatalf("CreateThread failed: %v", err)
	}
	h := syscall.Handle(r)
	defer syscall.CloseHandle(h)

	switch s, err := syscall.WaitForSingleObject(h, 100); s {
	case syscall.WAIT_OBJECT_0:
		break
	case syscall.WAIT_TIMEOUT:
		t.Fatal("timeout waiting for thread to exit")
	case syscall.WAIT_FAILED:
		t.Fatalf("WaitForSingleObject failed: %v", err)
	default:
		t.Fatalf("WaitForSingleObject returns unexpected value %v", s)
	}

	var ec uint32
	r, _, err = d.Proc("GetExitCodeThread").Call(uintptr(h), uintptr(unsafe.Pointer(&ec)))
	if r == 0 {
		t.Fatalf("GetExitCodeThread failed: %v", err)
	}
	if ec != 123 {
		t.Fatalf("expected 123, but got %d", ec)
	}
}

type cbFunc struct {
	goFunc any
}

func (f cbFunc) cName(cdecl bool) string {
	name := "stdcall"
	if cdecl {
		name = "cdecl"
	}
	t := reflect.TypeOf(f.goFunc)
	for i := 0; i < t.NumIn(); i++ {
		name += "_" + t.In(i).Name()
	}
	return name
}

func (f cbFunc) cSrc(w io.Writer, cdecl bool) {
	// Construct a C function that takes a callback with
	// f.goFunc's signature, and calls it with integers 1..N.
	funcname := f.cName(cdecl)
	attr := "__stdcall"
	if cdecl {
		attr = "__cdecl"
	}
	typename := "t" + funcname
	t := reflect.TypeOf(f.goFunc)
	cTypes := make([]string, t.NumIn())
	cArgs := make([]string, t.NumIn())
	for i := range cTypes {
		// We included stdint.h, so this works for all sized
		// integer types, and uint8Pair_t.
		cTypes[i] = t.In(i).Name() + "_t"
		if t.In(i).Name() == "uint8Pair" {
			cArgs[i] = fmt.Sprintf("(uint8Pair_t){%d,1}", i)
		} else {
			cArgs[i] = fmt.Sprintf("%d", i+1)
		}
	}
	fmt.Fprintf(w, `
typedef uintptr_t %s (*%s)(%s);
uintptr_t %s(%s f) {
	return f(%s);
}
	`, attr, typename, strings.Join(cTypes, ","), funcname, typename, strings.Join(cArgs, ","))
}

func (f cbFunc) testOne(t *testing.T, dll *syscall.DLL, cdecl bool, cb uintptr) {
	r1, _, _ := dll.MustFindProc(f.cName(cdecl)).Call(cb)

	want := 0
	for i := 0; i < reflect.TypeOf(f.goFunc).NumIn(); i++ {
		want += i + 1
	}
	if int(r1) != want {
		t.Errorf("wanted result %d; got %d", want, r1)
	}
}

type uint8Pair struct{ x, y uint8 }

var cbFuncs = []cbFunc{
	{func(i1, i2 uintptr) uintptr {
		return i1 + i2
	}},
	{func(i1, i2, i3 uintptr) uintptr {
		return i1 + i2 + i3
	}},
	{func(i1, i2, i3, i4 uintptr) uintptr {
		return i1 + i2 + i3 + i4
	}},
	{func(i1, i2, i3, i4, i5 uintptr) uintptr {
		return i1 + i2 + i3 + i4 + i5
	}},
	{func(i1, i2, i3, i4, i5, i6 uintptr) uintptr {
		return i1 + i2 + i3 + i4 + i5 + i6
	}},
	{func(i1, i2, i3, i4, i5, i6, i7 uintptr) uintptr {
		return i1 + i2 + i3 + i4 + i5 + i6 + i7
	}},
	{func(i1, i2, i3, i4, i5, i6, i7, i8 uintptr) uintptr {
		return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8
	}},
	{func(i1, i2, i3, i4, i5, i6, i7, i8, i9 uintptr) uintptr {
		return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9
	}},

	// Non-uintptr parameters.
	{func(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint8) uintptr {
		return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
	}},
	{func(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint16) uintptr {
		return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
	}},
	{func(i1, i2, i3, i4, i5, i6, i7, i8, i9 int8) uintptr {
		return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
	}},
	{func(i1 int8, i2 int16, i3 int32, i4, i5 uintptr) uintptr {
		return uintptr(i1) + uintptr(i2) + uintptr(i3) + i4 + i5
	}},
	{func(i1, i2, i3, i4, i5 uint8Pair) uintptr {
		return uintptr(i1.x + i1.y + i2.x + i2.y + i3.x + i3.y + i4.x + i4.y + i5.x + i5.y)
	}},
	{func(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint32) uintptr {
		runtime.GC()
		return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
	}},
}

//go:registerparams
func sum2(i1, i2 uintptr) uintptr {
	return i1 + i2
}

//go:registerparams
func sum3(i1, i2, i3 uintptr) uintptr {
	return i1 + i2 + i3
}

//go:registerparams
func sum4(i1, i2, i3, i4 uintptr) uintptr {
	return i1 + i2 + i3 + i4
}

//go:registerparams
func sum5(i1, i2, i3, i4, i5 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5
}

//go:registerparams
func sum6(i1, i2, i3, i4, i5, i6 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5 + i6
}

//go:registerparams
func sum7(i1, i2, i3, i4, i5, i6, i7 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5 + i6 + i7
}

//go:registerparams
func sum8(i1, i2, i3, i4, i5, i6, i7, i8 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8
}

//go:registerparams
func sum9(i1, i2, i3, i4, i5, i6, i7, i8, i9 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9
}

//go:registerparams
func sum10(i1, i2, i3, i4, i5, i6, i7, i8, i9, i10 uintptr) uintptr {
	return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9 + i10
}

//go:registerparams
func sum9uint8(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint8) uintptr {
	return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}

//go:registerparams
func sum9uint16(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint16) uintptr {
	return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}

//go:registerparams
func sum9int8(i1, i2, i3, i4, i5, i6, i7, i8, i9 int8) uintptr {
	return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}

//go:registerparams
func sum5mix(i1 int8, i2 int16, i3 int32, i4, i5 uintptr) uintptr {
	return uintptr(i1) + uintptr(i2) + uintptr(i3) + i4 + i5
}

//go:registerparams
func sum5andPair(i1, i2, i3, i4, i5 uint8Pair) uintptr {
	return uintptr(i1.x + i1.y + i2.x + i2.y + i3.x + i3.y + i4.x + i4.y + i5.x + i5.y)
}

// This test forces a GC. The idea is to have enough arguments
// that insufficient spill slots allocated (according to the ABI)
// may cause compiler-generated spills to clobber the return PC.
// Then, the GC stack scanning will catch that.
//
//go:registerparams
func sum9andGC(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint32) uintptr {
	runtime.GC()
	return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}

// TODO(register args): Remove this once we switch to using the register
// calling convention by default, since this is redundant with the existing
// tests.
var cbFuncsRegABI = []cbFunc{
	{sum2},
	{sum3},
	{sum4},
	{sum5},
	{sum6},
	{sum7},
	{sum8},
	{sum9},
	{sum10},
	{sum9uint8},
	{sum9uint16},
	{sum9int8},
	{sum5mix},
	{sum5andPair},
	{sum9andGC},
}

func getCallbackTestFuncs() []cbFunc {
	if regs := runtime.SetIntArgRegs(-1); regs > 0 {
		return cbFuncsRegABI
	}
	return cbFuncs
}

type cbDLL struct {
	name      string
	buildArgs func(out, src string) []string
}

func (d *cbDLL) makeSrc(t *testing.T, path string) {
	f, err := os.Create(path)
	if err != nil {
		t.Fatalf("failed to create source file: %v", err)
	}
	defer f.Close()

	fmt.Fprint(f, `
#include <stdint.h>
typedef struct { uint8_t x, y; } uint8Pair_t;
`)
	for _, cbf := range getCallbackTestFuncs() {
		cbf.cSrc(f, false)
		cbf.cSrc(f, true)
	}
}

func (d *cbDLL) build(t *testing.T, dir string) string {
	srcname := d.name + ".c"
	d.makeSrc(t, filepath.Join(dir, srcname))
	outname := d.name + ".dll"
	args := d.buildArgs(outname, srcname)
	cmd := exec.Command(args[0], args[1:]...)
	cmd.Dir = dir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	return filepath.Join(dir, outname)
}

var cbDLLs = []cbDLL{
	{
		"test",
		func(out, src string) []string {
			return []string{"gcc", "-shared", "-s", "-Werror", "-o", out, src}
		},
	},
	{
		"testO2",
		func(out, src string) []string {
			return []string{"gcc", "-shared", "-s", "-Werror", "-o", out, "-O2", src}
		},
	},
}

func TestStdcallAndCDeclCallbacks(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}
	tmp := t.TempDir()

	oldRegs := runtime.SetIntArgRegs(abi.IntArgRegs)
	defer runtime.SetIntArgRegs(oldRegs)

	for _, dll := range cbDLLs {
		t.Run(dll.name, func(t *testing.T) {
			dllPath := dll.build(t, tmp)
			dll := syscall.MustLoadDLL(dllPath)
			defer dll.Release()
			for _, cbf := range getCallbackTestFuncs() {
				t.Run(cbf.cName(false), func(t *testing.T) {
					stdcall := syscall.NewCallback(cbf.goFunc)
					cbf.testOne(t, dll, false, stdcall)
				})
				t.Run(cbf.cName(true), func(t *testing.T) {
					cdecl := syscall.NewCallbackCDecl(cbf.goFunc)
					cbf.testOne(t, dll, true, cdecl)
				})
			}
		})
	}
}

func TestRegisterClass(t *testing.T) {
	kernel32 := GetDLL(t, "kernel32.dll")
	user32 := GetDLL(t, "user32.dll")
	mh, _, _ := kernel32.Proc("GetModuleHandleW").Call(0)
	cb := syscall.NewCallback(func(hwnd syscall.Handle, msg uint32, wparam, lparam uintptr) (rc uintptr) {
		t.Fatal("callback should never get called")
		return 0
	})
	type Wndclassex struct {
		Size       uint32
		Style      uint32
		WndProc    uintptr
		ClsExtra   int32
		WndExtra   int32
		Instance   syscall.Handle
		Icon       syscall.Handle
		Cursor     syscall.Handle
		Background syscall.Handle
		MenuName   *uint16
		ClassName  *uint16
		IconSm     syscall.Handle
	}
	name := syscall.StringToUTF16Ptr("test_window")
	wc := Wndclassex{
		WndProc:   cb,
		Instance:  syscall.Handle(mh),
		ClassName: name,
	}
	wc.Size = uint32(unsafe.Sizeof(wc))
	a, _, err := user32.Proc("RegisterClassExW").Call(uintptr(unsafe.Pointer(&wc)))
	if a == 0 {
		t.Fatalf("RegisterClassEx failed: %v", err)
	}
	r, _, err := user32.Proc("UnregisterClassW").Call(uintptr(unsafe.Pointer(name)), 0)
	if r == 0 {
		t.Fatalf("UnregisterClass failed: %v", err)
	}
}

func TestOutputDebugString(t *testing.T) {
	d := GetDLL(t, "kernel32.dll")
	p := syscall.StringToUTF16Ptr("testing OutputDebugString")
	d.Proc("OutputDebugStringW").Call(uintptr(unsafe.Pointer(p)))
}

func TestRaiseException(t *testing.T) {
	if strings.HasPrefix(testenv.Builder(), "windows-amd64-2012") {
		testenv.SkipFlaky(t, 49681)
	}
	o := runTestProg(t, "testprog", "RaiseException")
	if strings.Contains(o, "RaiseException should not return") {
		t.Fatalf("RaiseException did not crash program: %v", o)
	}
	if !strings.Contains(o, "Exception 0xbad") {
		t.Fatalf("No stack trace: %v", o)
	}
}

func TestZeroDivisionException(t *testing.T) {
	o := runTestProg(t, "testprog", "ZeroDivisionException")
	if !strings.Contains(o, "panic: runtime error: integer divide by zero") {
		t.Fatalf("No stack trace: %v", o)
	}
}

func TestWERDialogue(t *testing.T) {
	if os.Getenv("TESTING_WER_DIALOGUE") == "1" {
		defer os.Exit(0)

		*runtime.TestingWER = true
		const EXCEPTION_NONCONTINUABLE = 1
		mod := syscall.MustLoadDLL("kernel32.dll")
		proc := mod.MustFindProc("RaiseException")
		proc.Call(0xbad, EXCEPTION_NONCONTINUABLE, 0, 0)
		println("RaiseException should not return")
		return
	}
	cmd := exec.Command(os.Args[0], "-test.run=TestWERDialogue")
	cmd.Env = []string{"TESTING_WER_DIALOGUE=1"}
	// Child process should not open WER dialogue, but return immediately instead.
	cmd.CombinedOutput()
}

func TestWindowsStackMemory(t *testing.T) {
	o := runTestProg(t, "testprog", "StackMemory")
	stackUsage, err := strconv.Atoi(o)
	if err != nil {
		t.Fatalf("Failed to read stack usage: %v", err)
	}
	if expected, got := 100<<10, stackUsage; got > expected {
		t.Fatalf("expected < %d bytes of memory per thread, got %d", expected, got)
	}
}

var used byte

func use(buf []byte) {
	for _, c := range buf {
		used += c
	}
}

func forceStackCopy() (r int) {
	var f func(int) int
	f = func(i int) int {
		var buf [256]byte
		use(buf[:])
		if i == 0 {
			return 0
		}
		return i + f(i-1)
	}
	r = f(128)
	return
}

func TestReturnAfterStackGrowInCallback(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}

	const src = `
#include <stdint.h>
#include <windows.h>

typedef uintptr_t __stdcall (*callback)(uintptr_t);

uintptr_t cfunc(callback f, uintptr_t n) {
   uintptr_t r;
   r = f(n);
   SetLastError(333);
   return r;
}
`
	tmpdir := t.TempDir()

	srcname := "mydll.c"
	err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
	if err != nil {
		t.Fatal(err)
	}
	outname := "mydll.dll"
	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	dllpath := filepath.Join(tmpdir, outname)

	dll := syscall.MustLoadDLL(dllpath)
	defer dll.Release()

	proc := dll.MustFindProc("cfunc")

	cb := syscall.NewCallback(func(n uintptr) uintptr {
		forceStackCopy()
		return n
	})

	// Use a new goroutine so that we get a small stack.
	type result struct {
		r   uintptr
		err syscall.Errno
	}
	want := result{
		// Make it large enough to test issue #29331.
		r:   (^uintptr(0)) >> 24,
		err: 333,
	}
	c := make(chan result)
	go func() {
		r, _, err := proc.Call(cb, want.r)
		c <- result{r, err.(syscall.Errno)}
	}()
	if got := <-c; got != want {
		t.Errorf("got %d want %d", got, want)
	}
}

func TestSyscallN(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}
	if runtime.GOARCH != "amd64" {
		t.Skipf("skipping test: GOARCH=%s", runtime.GOARCH)
	}

	for arglen := 0; arglen <= runtime.MaxArgs; arglen++ {
		arglen := arglen
		t.Run(fmt.Sprintf("arg-%d", arglen), func(t *testing.T) {
			t.Parallel()
			args := make([]string, arglen)
			rets := make([]string, arglen+1)
			params := make([]uintptr, arglen)
			for i := range args {
				args[i] = fmt.Sprintf("int a%d", i)
				rets[i] = fmt.Sprintf("(a%d == %d)", i, i)
				params[i] = uintptr(i)
			}
			rets[arglen] = "1" // for arglen == 0

			src := fmt.Sprintf(`
		#include <stdint.h>
		#include <windows.h>
		int cfunc(%s) { return %s; }`, strings.Join(args, ", "), strings.Join(rets, " && "))

			tmpdir := t.TempDir()

			srcname := "mydll.c"
			err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
			if err != nil {
				t.Fatal(err)
			}
			outname := "mydll.dll"
			cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
			cmd.Dir = tmpdir
			out, err := cmd.CombinedOutput()
			if err != nil {
				t.Fatalf("failed to build dll: %v\n%s", err, out)
			}
			dllpath := filepath.Join(tmpdir, outname)

			dll := syscall.MustLoadDLL(dllpath)
			defer dll.Release()

			proc := dll.MustFindProc("cfunc")

			// proc.Call() will call SyscallN() internally.
			r, _, err := proc.Call(params...)
			if r != 1 {
				t.Errorf("got %d want 1 (err=%v)", r, err)
			}
		})
	}
}

func TestFloatArgs(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}
	if runtime.GOARCH != "amd64" {
		t.Skipf("skipping test: GOARCH=%s", runtime.GOARCH)
	}

	const src = `
#include <stdint.h>
#include <windows.h>

uintptr_t cfunc(uintptr_t a, double b, float c, double d) {
	if (a == 1 && b == 2.2 && c == 3.3f && d == 4.4e44) {
		return 1;
	}
	return 0;
}
`
	tmpdir := t.TempDir()

	srcname := "mydll.c"
	err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
	if err != nil {
		t.Fatal(err)
	}
	outname := "mydll.dll"
	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	dllpath := filepath.Join(tmpdir, outname)

	dll := syscall.MustLoadDLL(dllpath)
	defer dll.Release()

	proc := dll.MustFindProc("cfunc")

	r, _, err := proc.Call(
		1,
		uintptr(math.Float64bits(2.2)),
		uintptr(math.Float32bits(3.3)),
		uintptr(math.Float64bits(4.4e44)),
	)
	if r != 1 {
		t.Errorf("got %d want 1 (err=%v)", r, err)
	}
}

func TestFloatReturn(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}
	if runtime.GOARCH != "amd64" {
		t.Skipf("skipping test: GOARCH=%s", runtime.GOARCH)
	}

	const src = `
#include <stdint.h>
#include <windows.h>

float cfuncFloat(uintptr_t a, double b, float c, double d) {
	if (a == 1 && b == 2.2 && c == 3.3f && d == 4.4e44) {
		return 1.5f;
	}
	return 0;
}

double cfuncDouble(uintptr_t a, double b, float c, double d) {
	if (a == 1 && b == 2.2 && c == 3.3f && d == 4.4e44) {
		return 2.5;
	}
	return 0;
}
`
	tmpdir := t.TempDir()

	srcname := "mydll.c"
	err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
	if err != nil {
		t.Fatal(err)
	}
	outname := "mydll.dll"
	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	dllpath := filepath.Join(tmpdir, outname)

	dll := syscall.MustLoadDLL(dllpath)
	defer dll.Release()

	proc := dll.MustFindProc("cfuncFloat")

	_, r, err := proc.Call(
		1,
		uintptr(math.Float64bits(2.2)),
		uintptr(math.Float32bits(3.3)),
		uintptr(math.Float64bits(4.4e44)),
	)
	fr := math.Float32frombits(uint32(r))
	if fr != 1.5 {
		t.Errorf("got %f want 1.5 (err=%v)", fr, err)
	}

	proc = dll.MustFindProc("cfuncDouble")

	_, r, err = proc.Call(
		1,
		uintptr(math.Float64bits(2.2)),
		uintptr(math.Float32bits(3.3)),
		uintptr(math.Float64bits(4.4e44)),
	)
	dr := math.Float64frombits(uint64(r))
	if dr != 2.5 {
		t.Errorf("got %f want 2.5 (err=%v)", dr, err)
	}
}

func TestTimeBeginPeriod(t *testing.T) {
	const TIMERR_NOERROR = 0
	if *runtime.TimeBeginPeriodRetValue != TIMERR_NOERROR {
		t.Fatalf("timeBeginPeriod failed: it returned %d", *runtime.TimeBeginPeriodRetValue)
	}
}

// removeOneCPU removes one (any) cpu from affinity mask.
// It returns new affinity mask.
func removeOneCPU(mask uintptr) (uintptr, error) {
	if mask == 0 {
		return 0, fmt.Errorf("cpu affinity mask is empty")
	}
	maskbits := int(unsafe.Sizeof(mask) * 8)
	for i := 0; i < maskbits; i++ {
		newmask := mask & ^(1 << uint(i))
		if newmask != mask {
			return newmask, nil
		}

	}
	panic("not reached")
}

func resumeChildThread(kernel32 *syscall.DLL, childpid int) error {
	_OpenThread := kernel32.MustFindProc("OpenThread")
	_ResumeThread := kernel32.MustFindProc("ResumeThread")
	_Thread32First := kernel32.MustFindProc("Thread32First")
	_Thread32Next := kernel32.MustFindProc("Thread32Next")

	snapshot, err := syscall.CreateToolhelp32Snapshot(syscall.TH32CS_SNAPTHREAD, 0)
	if err != nil {
		return err
	}
	defer syscall.CloseHandle(snapshot)

	const _THREAD_SUSPEND_RESUME = 0x0002

	type ThreadEntry32 struct {
		Size           uint32
		tUsage         uint32
		ThreadID       uint32
		OwnerProcessID uint32
		BasePri        int32
		DeltaPri       int32
		Flags          uint32
	}

	var te ThreadEntry32
	te.Size = uint32(unsafe.Sizeof(te))
	ret, _, err := _Thread32First.Call(uintptr(snapshot), uintptr(unsafe.Pointer(&te)))
	if ret == 0 {
		return err
	}
	for te.OwnerProcessID != uint32(childpid) {
		ret, _, err = _Thread32Next.Call(uintptr(snapshot), uintptr(unsafe.Pointer(&te)))
		if ret == 0 {
			return err
		}
	}
	h, _, err := _OpenThread.Call(_THREAD_SUSPEND_RESUME, 1, uintptr(te.ThreadID))
	if h == 0 {
		return err
	}
	defer syscall.Close(syscall.Handle(h))

	ret, _, err = _ResumeThread.Call(h)
	if ret == 0xffffffff {
		return err
	}
	return nil
}

func TestNumCPU(t *testing.T) {
	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
		// in child process
		fmt.Fprintf(os.Stderr, "%d", runtime.NumCPU())
		os.Exit(0)
	}

	switch n := runtime.NumberOfProcessors(); {
	case n < 1:
		t.Fatalf("system cannot have %d cpu(s)", n)
	case n == 1:
		if runtime.NumCPU() != 1 {
			t.Fatalf("runtime.NumCPU() returns %d on single cpu system", runtime.NumCPU())
		}
		return
	}

	const (
		_CREATE_SUSPENDED   = 0x00000004
		_PROCESS_ALL_ACCESS = syscall.STANDARD_RIGHTS_REQUIRED | syscall.SYNCHRONIZE | 0xfff
	)

	kernel32 := syscall.MustLoadDLL("kernel32.dll")
	_GetProcessAffinityMask := kernel32.MustFindProc("GetProcessAffinityMask")
	_SetProcessAffinityMask := kernel32.MustFindProc("SetProcessAffinityMask")

	cmd := exec.Command(os.Args[0], "-test.run=TestNumCPU")
	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
	var buf bytes.Buffer
	cmd.Stdout = &buf
	cmd.Stderr = &buf
	cmd.SysProcAttr = &syscall.SysProcAttr{CreationFlags: _CREATE_SUSPENDED}
	err := cmd.Start()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = cmd.Wait()
		childOutput := string(buf.Bytes())
		if err != nil {
			t.Fatalf("child failed: %v: %v", err, childOutput)
		}
		// removeOneCPU should have decreased child cpu count by 1
		want := fmt.Sprintf("%d", runtime.NumCPU()-1)
		if childOutput != want {
			t.Fatalf("child output: want %q, got %q", want, childOutput)
		}
	}()

	defer func() {
		err = resumeChildThread(kernel32, cmd.Process.Pid)
		if err != nil {
			t.Fatal(err)
		}
	}()

	ph, err := syscall.OpenProcess(_PROCESS_ALL_ACCESS, false, uint32(cmd.Process.Pid))
	if err != nil {
		t.Fatal(err)
	}
	defer syscall.CloseHandle(ph)

	var mask, sysmask uintptr
	ret, _, err := _GetProcessAffinityMask.Call(uintptr(ph), uintptr(unsafe.Pointer(&mask)), uintptr(unsafe.Pointer(&sysmask)))
	if ret == 0 {
		t.Fatal(err)
	}

	newmask, err := removeOneCPU(mask)
	if err != nil {
		t.Fatal(err)
	}

	ret, _, err = _SetProcessAffinityMask.Call(uintptr(ph), newmask)
	if ret == 0 {
		t.Fatal(err)
	}
	ret, _, err = _GetProcessAffinityMask.Call(uintptr(ph), uintptr(unsafe.Pointer(&mask)), uintptr(unsafe.Pointer(&sysmask)))
	if ret == 0 {
		t.Fatal(err)
	}
	if newmask != mask {
		t.Fatalf("SetProcessAffinityMask didn't set newmask of 0x%x. Current mask is 0x%x.", newmask, mask)
	}
}

// See Issue 14959
func TestDLLPreloadMitigation(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}

	tmpdir := t.TempDir()

	dir0, err := os.Getwd()
	if err != nil {
		t.Fatal(err)
	}
	defer os.Chdir(dir0)

	const src = `
#include <stdint.h>
#include <windows.h>

uintptr_t cfunc(void) {
   SetLastError(123);
   return 0;
}
`
	srcname := "nojack.c"
	err = os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
	if err != nil {
		t.Fatal(err)
	}
	name := "nojack.dll"
	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", name, srcname)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	dllpath := filepath.Join(tmpdir, name)

	dll := syscall.MustLoadDLL(dllpath)
	dll.MustFindProc("cfunc")
	dll.Release()

	// Get into the directory with the DLL we'll load by base name
	// ("nojack.dll") Think of this as the user double-clicking an
	// installer from their Downloads directory where a browser
	// silently downloaded some malicious DLLs.
	os.Chdir(tmpdir)

	// First before we can load a DLL from the current directory,
	// loading it only as "nojack.dll", without an absolute path.
	delete(sysdll.IsSystemDLL, name) // in case test was run repeatedly
	dll, err = syscall.LoadDLL(name)
	if err != nil {
		t.Fatalf("failed to load %s by base name before sysdll registration: %v", name, err)
	}
	dll.Release()

	// And now verify that if we register it as a system32-only
	// DLL, the implicit loading from the current directory no
	// longer works.
	sysdll.IsSystemDLL[name] = true
	dll, err = syscall.LoadDLL(name)
	if err == nil {
		dll.Release()
		if wantLoadLibraryEx() {
			t.Fatalf("Bad: insecure load of DLL by base name %q before sysdll registration: %v", name, err)
		}
		t.Skip("insecure load of DLL, but expected")
	}
}

// Test that C code called via a DLL can use large Windows thread
// stacks and call back in to Go without crashing. See issue #20975.
//
// See also TestBigStackCallbackCgo.
func TestBigStackCallbackSyscall(t *testing.T) {
	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}

	srcname, err := filepath.Abs("testdata/testprogcgo/bigstack_windows.c")
	if err != nil {
		t.Fatal("Abs failed: ", err)
	}

	tmpdir := t.TempDir()

	outname := "mydll.dll"
	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("failed to build dll: %v - %v", err, string(out))
	}
	dllpath := filepath.Join(tmpdir, outname)

	dll := syscall.MustLoadDLL(dllpath)
	defer dll.Release()

	var ok bool
	proc := dll.MustFindProc("bigStack")
	cb := syscall.NewCallback(func() uintptr {
		// Do something interesting to force stack checks.
		forceStackCopy()
		ok = true
		return 0
	})
	proc.Call(cb)
	if !ok {
		t.Fatalf("callback not called")
	}
}

// wantLoadLibraryEx reports whether we expect LoadLibraryEx to work for tests.
func wantLoadLibraryEx() bool {
	return testenv.Builder() == "windows-amd64-gce" || testenv.Builder() == "windows-386-gce"
}

func TestLoadLibraryEx(t *testing.T) {
	use, have, flags := runtime.LoadLibraryExStatus()
	if use {
		return // success.
	}
	if wantLoadLibraryEx() {
		t.Fatalf("Expected LoadLibraryEx+flags to be available. (LoadLibraryEx=%v; flags=%v)",
			have, flags)
	}
	t.Skipf("LoadLibraryEx not usable, but not expected. (LoadLibraryEx=%v; flags=%v)",
		have, flags)
}

var (
	modwinmm    = syscall.NewLazyDLL("winmm.dll")
	modkernel32 = syscall.NewLazyDLL("kernel32.dll")

	procCreateEvent = modkernel32.NewProc("CreateEventW")
	procSetEvent    = modkernel32.NewProc("SetEvent")
)

func createEvent() (syscall.Handle, error) {
	r0, _, e0 := syscall.Syscall6(procCreateEvent.Addr(), 4, 0, 0, 0, 0, 0, 0)
	if r0 == 0 {
		return 0, syscall.Errno(e0)
	}
	return syscall.Handle(r0), nil
}

func setEvent(h syscall.Handle) error {
	r0, _, e0 := syscall.Syscall(procSetEvent.Addr(), 1, uintptr(h), 0, 0)
	if r0 == 0 {
		return syscall.Errno(e0)
	}
	return nil
}

func BenchmarkChanToSyscallPing(b *testing.B) {
	n := b.N
	ch := make(chan int)
	event, err := createEvent()
	if err != nil {
		b.Fatal(err)
	}
	go func() {
		for i := 0; i < n; i++ {
			syscall.WaitForSingleObject(event, syscall.INFINITE)
			ch <- 1
		}
	}()
	for i := 0; i < n; i++ {
		err := setEvent(event)
		if err != nil {
			b.Fatal(err)
		}
		<-ch
	}
}

func BenchmarkSyscallToSyscallPing(b *testing.B) {
	n := b.N
	event1, err := createEvent()
	if err != nil {
		b.Fatal(err)
	}
	event2, err := createEvent()
	if err != nil {
		b.Fatal(err)
	}
	go func() {
		for i := 0; i < n; i++ {
			syscall.WaitForSingleObject(event1, syscall.INFINITE)
			if err := setEvent(event2); err != nil {
				b.Errorf("Set event failed: %v", err)
				return
			}
		}
	}()
	for i := 0; i < n; i++ {
		if err := setEvent(event1); err != nil {
			b.Fatal(err)
		}
		if b.Failed() {
			break
		}
		syscall.WaitForSingleObject(event2, syscall.INFINITE)
	}
}

func BenchmarkChanToChanPing(b *testing.B) {
	n := b.N
	ch1 := make(chan int)
	ch2 := make(chan int)
	go func() {
		for i := 0; i < n; i++ {
			<-ch1
			ch2 <- 1
		}
	}()
	for i := 0; i < n; i++ {
		ch1 <- 1
		<-ch2
	}
}

func BenchmarkOsYield(b *testing.B) {
	for i := 0; i < b.N; i++ {
		runtime.OsYield()
	}
}

func BenchmarkRunningGoProgram(b *testing.B) {
	tmpdir := b.TempDir()

	src := filepath.Join(tmpdir, "main.go")
	err := os.WriteFile(src, []byte(benchmarkRunningGoProgram), 0666)
	if err != nil {
		b.Fatal(err)
	}

	exe := filepath.Join(tmpdir, "main.exe")
	cmd := exec.Command(testenv.GoToolPath(b), "build", "-o", exe, src)
	cmd.Dir = tmpdir
	out, err := cmd.CombinedOutput()
	if err != nil {
		b.Fatalf("building main.exe failed: %v\n%s", err, out)
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		cmd := exec.Command(exe)
		out, err := cmd.CombinedOutput()
		if err != nil {
			b.Fatalf("running main.exe failed: %v\n%s", err, out)
		}
	}
}

const benchmarkRunningGoProgram = `
package main

import _ "os" // average Go program will use "os" package, do the same here

func main() {
}
`