code review 4029053: os: implement new Process api

src/pkg/os/exec_windows.go

 // Copyright 2009 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 os
 
-import "syscall"
+import (
+        "runtime"
+        "syscall"
+)
 
 func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
         s, e := syscall.WaitForSingleObject(int32(p.handle), syscall.INFINITE)
         switch s {
         case syscall.WAIT_OBJECT_0:
                 break
         case syscall.WAIT_FAILED:
                 return nil, NewSyscallError("WaitForSingleObject", e)
         default:
                 return nil, ErrorString("os: unexpected result from WaitForSingleObject")
         }
         var ec uint32
         if ok, e := syscall.GetExitCodeProcess(uint32(p.handle), &ec); !ok {
                 return nil, NewSyscallError("GetExitCodeProcess", e)
         }
         return &Waitmsg{p.Pid, syscall.WaitStatus{s, ec}, new(syscall.Rusage)}, nil
 }
 
 func (p *Process) Release() Error {
         if p.handle == -1 {
-                return ErrorString("os: Process is already released")
+                return EINVAL
         }
         if ok, e := syscall.CloseHandle(int32(p.handle)); !ok {
                 return NewSyscallError("CloseHandle", e)
         }
         p.handle = -1
+        // no need for a finalizer anymore
+        runtime.SetFinalizer(p, nil)
         return nil
 }
 
 func FindProcess(pid int) (p *Process, err Error) {
         const da = syscall.STANDARD_RIGHTS_READ |
                 syscall.PROCESS_QUERY_INFORMATION | syscall.SYNCHRONIZE
         h, e := syscall.OpenProcess(da, false, uint32(pid))
         if e != 0 {
                 return nil, NewSyscallError("OpenProcess", e)
         }
-        return &Process{pid, int(h)}, nil
+        return newProcess(pid, int(h)), nil
 }