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// Copyright 2013 @atotto. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build windows
package clipboard
import (
"runtime"
"syscall"
"time"
"unsafe"
)
const (
cfUnicodetext = 13
gmemMoveable = 0x0002
)
var (
user32 = syscall.MustLoadDLL("user32")
isClipboardFormatAvailable = user32.MustFindProc("IsClipboardFormatAvailable")
openClipboard = user32.MustFindProc("OpenClipboard")
closeClipboard = user32.MustFindProc("CloseClipboard")
emptyClipboard = user32.MustFindProc("EmptyClipboard")
getClipboardData = user32.MustFindProc("GetClipboardData")
setClipboardData = user32.MustFindProc("SetClipboardData")
kernel32 = syscall.NewLazyDLL("kernel32")
globalAlloc = kernel32.NewProc("GlobalAlloc")
globalFree = kernel32.NewProc("GlobalFree")
globalLock = kernel32.NewProc("GlobalLock")
globalUnlock = kernel32.NewProc("GlobalUnlock")
lstrcpy = kernel32.NewProc("lstrcpyW")
)
// waitOpenClipboard opens the clipboard, waiting for up to a second to do so.
func waitOpenClipboard() error {
started := time.Now()
limit := started.Add(time.Second)
var r uintptr
var err error
for time.Now().Before(limit) {
r, _, err = openClipboard.Call(0)
if r != 0 {
return nil
}
time.Sleep(time.Millisecond)
}
return err
}
func readAll() (string, error) {
// LockOSThread ensure that the whole method will keep executing on the same thread from begin to end (it actually locks the goroutine thread attribution).
// Otherwise if the goroutine switch thread during execution (which is a common practice), the OpenClipboard and CloseClipboard will happen on two different threads, and it will result in a clipboard deadlock.
runtime.LockOSThread()
defer runtime.UnlockOSThread()
if formatAvailable, _, err := isClipboardFormatAvailable.Call(cfUnicodetext); formatAvailable == 0 {
return "", err
}
err := waitOpenClipboard()
if err != nil {
return "", err
}
h, _, err := getClipboardData.Call(cfUnicodetext)
if h == 0 {
_, _, _ = closeClipboard.Call()
return "", err
}
l, _, err := globalLock.Call(h)
if l == 0 {
_, _, _ = closeClipboard.Call()
return "", err
}
text := syscall.UTF16ToString((*[1 << 20]uint16)(unsafe.Pointer(l))[:])
r, _, err := globalUnlock.Call(h)
if r == 0 {
_, _, _ = closeClipboard.Call()
return "", err
}
closed, _, err := closeClipboard.Call()
if closed == 0 {
return "", err
}
return text, nil
}
func writeAll(text string) error {
// LockOSThread ensure that the whole method will keep executing on the same thread from begin to end (it actually locks the goroutine thread attribution).
// Otherwise if the goroutine switch thread during execution (which is a common practice), the OpenClipboard and CloseClipboard will happen on two different threads, and it will result in a clipboard deadlock.
runtime.LockOSThread()
defer runtime.UnlockOSThread()
err := waitOpenClipboard()
if err != nil {
return err
}
r, _, err := emptyClipboard.Call(0)
if r == 0 {
_, _, _ = closeClipboard.Call()
return err
}
data := syscall.StringToUTF16(text)
// "If the hMem parameter identifies a memory object, the object must have
// been allocated using the function with the GMEM_MOVEABLE flag."
h, _, err := globalAlloc.Call(gmemMoveable, uintptr(len(data)*int(unsafe.Sizeof(data[0]))))
if h == 0 {
_, _, _ = closeClipboard.Call()
return err
}
defer func() {
if h != 0 {
globalFree.Call(h)
}
}()
l, _, err := globalLock.Call(h)
if l == 0 {
_, _, _ = closeClipboard.Call()
return err
}
r, _, err = lstrcpy.Call(l, uintptr(unsafe.Pointer(&data[0])))
if r == 0 {
_, _, _ = closeClipboard.Call()
return err
}
r, _, err = globalUnlock.Call(h)
if r == 0 {
if err.(syscall.Errno) != 0 {
_, _, _ = closeClipboard.Call()
return err
}
}
r, _, err = setClipboardData.Call(cfUnicodetext, h)
if r == 0 {
_, _, _ = closeClipboard.Call()
return err
}
h = 0 // suppress deferred cleanup
closed, _, err := closeClipboard.Call()
if closed == 0 {
return err
}
return nil
}
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