Initialize COM around file dialogs.

file_windows.go

@@ -1,8 +1,10 @@
 package zenity
 
 import (
+	"context"
 	"fmt"
 	"path/filepath"
+	"runtime"
 	"syscall"
 	"unicode/utf16"
 	"unsafe"
@@ -36,6 +38,12 @@ func selectFile(opts options) (string, error) {
 	args.MaxFile = uint32(len(res))
 	args.InitialDir, args.DefExt = initDirNameExt(opts.filename, res[:])
 
+	uninit, err := coInitialize()
+	if err != nil {
+		return "", err
+	}
+	defer uninit()
+
 	defer setup(args.Owner)()
 	unhook, err := hookDialog(opts.ctx, opts.windowIcon, nil, nil)
 	if err != nil {
@@ -79,6 +87,12 @@ func selectFileMultiple(opts options) ([]string, error) {
 	args.MaxFile = uint32(len(res))
 	args.InitialDir, args.DefExt = initDirNameExt(opts.filename, res[:])
 
+	uninit, err := coInitialize()
+	if err != nil {
+		return nil, err
+	}
+	defer uninit()
+
 	defer setup(args.Owner)()
 	unhook, err := hookDialog(opts.ctx, opts.windowIcon, nil, nil)
 	if err != nil {
@@ -153,6 +167,12 @@ func selectFileSave(opts options) (string, error) {
 	args.MaxFile = uint32(len(res))
 	args.InitialDir, args.DefExt = initDirNameExt(opts.filename, res[:])
 
+	uninit, err := coInitialize()
+	if err != nil {
+		return "", err
+	}
+	defer uninit()
+
 	defer setup(args.Owner)()
 	unhook, err := hookDialog(opts.ctx, opts.windowIcon, nil, nil)
 	if err != nil {
@@ -171,17 +191,15 @@ func selectFileSave(opts options) (string, error) {
 }
 
 func pickFolders(opts options, multi bool) (string, []string, error) {
+	uninit, err := coInitialize()
+	if err != nil {
+		return "", nil, err
+	}
+	defer uninit()
+
 	owner, _ := opts.attach.(win.HWND)
 	defer setup(owner)()
 
-	err := win.CoInitializeEx(0, win.COINIT_APARTMENTTHREADED|win.COINIT_DISABLE_OLE1DDE)
-	if err != win.RPC_E_CHANGED_MODE {
-		if err != nil {
-			return "", nil, err
-		}
-		defer win.CoUninitialize()
-	}
-
 	var dialog *win.IFileOpenDialog
 	err = win.CoCreateInstance(
 		win.CLSID_FileOpenDialog, nil, win.CLSCTX_ALL,
@@ -320,6 +338,22 @@ func browseForFolderCallback(wnd win.HWND, msg uint32, lparam, data uintptr) uin
 	return 0
 }
 
+func coInitialize() (context.CancelFunc, error) {
+	runtime.LockOSThread()
+	err := win.CoInitializeEx(0, win.COINIT_APARTMENTTHREADED|win.COINIT_DISABLE_OLE1DDE)
+	if err == nil || err == win.S_FALSE {
+		return func() {
+			win.CoUninitialize()
+			runtime.UnlockOSThread()
+		}, nil
+	}
+	if err == win.RPC_E_CHANGED_MODE {
+		return runtime.UnlockOSThread, nil
+	}
+	runtime.UnlockOSThread()
+	return nil, err
+}
+
 func initDirNameExt(filename string, name []uint16) (dir *uint16, ext *uint16) {
 	d, n, _ := splitDirAndName(filename)
 	e := filepath.Ext(n)

internal/win/ole32.go

@@ -24,6 +24,7 @@ const (
 
 	E_CANCELED         = windows.ERROR_CANCELLED | windows.FACILITY_WIN32<<16 | 0x80000000
 	RPC_E_CHANGED_MODE = syscall.Errno(windows.RPC_E_CHANGED_MODE)
+	S_FALSE            = syscall.Errno(windows.S_FALSE)
 )
 
 func CoInitializeEx(reserved uintptr, coInit uint32) error {