//go:build windows
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package singleinstance
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import (
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"fmt"
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"syscall"
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"unsafe"
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)
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var (
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kernel32 = syscall.NewLazyDLL("kernel32.dll")
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procCreateMutex = kernel32.NewProc("CreateMutexW")
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procReleaseMutex = kernel32.NewProc("ReleaseMutex")
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procCloseHandle = kernel32.NewProc("CloseHandle")
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)
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const errorAlreadyExists = 183
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type windowsLock struct {
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handle syscall.Handle
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}
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// Acquire tries to acquire a named mutex. Returns error if another instance holds it.
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func Acquire() (Lock, error) {
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name, err := syscall.UTF16PtrFromString("Global\\VoiceSnapSingleInstance")
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if err != nil {
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return nil, err
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}
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handle, _, err := procCreateMutex.Call(0, 0, uintptr(unsafe.Pointer(name)))
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if handle == 0 {
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return nil, fmt.Errorf("CreateMutex failed: %v", err)
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}
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if err.(syscall.Errno) == errorAlreadyExists {
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procCloseHandle.Call(handle)
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return nil, fmt.Errorf("another instance is already running")
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}
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return &windowsLock{handle: syscall.Handle(handle)}, nil
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}
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func (l *windowsLock) Release() {
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if l.handle != 0 {
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procReleaseMutex.Call(uintptr(l.handle))
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procCloseHandle.Call(uintptr(l.handle))
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l.handle = 0
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}
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}
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