windows/svc: correct MOVL instruction in sys_amd64.s

Second argument of servicemain is a pointer. See

https://msdn.microsoft.com/en-us/library/windows/desktop/ms685138(v=vs.85).aspx

So amd64 assembler code should use MOVQ to read that value.
I probably copied 386 assembler code into amd64 and did not
adjust the code.

Broken code was used to pass parameters to the service, so
add some tests to verify that parameter passing works.

Fixes golang/go#24575

Change-Id: I89f8cad026ea13f8a5d78ff3e24b7236e27fc91f
Reviewed-on: https://go-review.googlesource.com/110160
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

windows/svc/example/service.go

@@ -8,6 +8,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 	"time"
 
 	"golang.org/x/sys/windows/svc"
@@ -26,6 +27,7 @@ func (m *myservice) Execute(args []string, r <-chan svc.ChangeRequest, changes c
 	slowtick := time.Tick(2 * time.Second)
 	tick := fasttick
 	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
+	elog.Info(1, strings.Join(args, "-"))
 loop:
 	for {
 		select {

windows/svc/svc_test.go

@@ -7,10 +7,13 @@
 package svc_test
 
 import (
+	"fmt"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -86,8 +89,10 @@ func TestExample(t *testing.T) {
 	}
 	defer s.Close()
 
+	args := []string{"is", "manual-started", fmt.Sprintf("%d", rand.Int())}
+
 	testState(t, s, svc.Stopped)
-	err = s.Start("is", "manual-started")
+	err = s.Start(args...)
 	if err != nil {
 		t.Fatalf("Start(%s) failed: %s", s.Name, err)
 	}
@@ -115,4 +120,16 @@ func TestExample(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Delete failed: %s", err)
 	}
+
+	cmd := `Get-Eventlog -LogName Application -Newest 100` +
+		` | Where Source -eq "myservice"` +
+		` | Select -first 10` +
+		` | Format-table -HideTableHeaders -property ReplacementStrings`
+	out, err := exec.Command("powershell", "-Command", cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("powershell failed: %v\n%v", err, string(out))
+	}
+	if want := strings.Join(append([]string{name}, args...), "-"); !strings.Contains(string(out), want) {
+		t.Errorf("%q string does not contain %q", string(out), want)
+	}
 }

windows/svc/sys_amd64.s

@@ -7,7 +7,7 @@
 // func servicemain(argc uint32, argv **uint16)
 TEXT ·servicemain(SB),7,$0
 	MOVL	CX, ·sArgc(SB)
-	MOVL	DX, ·sArgv(SB)
+	MOVQ	DX, ·sArgv(SB)
 
 	SUBQ	$32, SP		// stack for the first 4 syscall params