aliyun / credentials-go

package providers

import (

	"syscall"

	"unsafe"

)

var (

	modkernel32      = syscall.NewLazyDLL("kernel32.dll")

	procLockFileEx   = modkernel32.NewProc("LockFileEx")

	procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")

)

const (

	// LOCKFILE_EXCLUSIVE_LOCK - request exclusive lock

	lockfileExclusiveLock = 0x00000002

)

// lockFile acquires an exclusive lock on the file using Windows LockFileEx

func lockFile(fd int) error {

	// LockFileEx parameters:

	// - hFile: file handle

	// - dwFlags: LOCKFILE_EXCLUSIVE_LOCK for exclusive lock

	// - dwReserved: must be 0

	// - nNumberOfBytesToLockLow: low-order 32 bits of lock range (1 byte is enough)

	// - nNumberOfBytesToLockHigh: high-order 32 bits of lock range

	// - lpOverlapped: pointer to OVERLAPPED structure

	var overlapped syscall.Overlapped

	r1, _, err := procLockFileEx.Call(

		uintptr(fd),

		uintptr(lockfileExclusiveLock),

		0,

		1,

		0,

		uintptr(unsafe.Pointer(&overlapped)),

	)

	if r1 == 0 {

		return err

	}

	return nil

}

// unlockFile releases the lock on the file using Windows UnlockFileEx

func unlockFile(fd int) error {

	var overlapped syscall.Overlapped

	r1, _, err := procUnlockFileEx.Call(

		uintptr(fd),

		0,

		1,

		0,

		uintptr(unsafe.Pointer(&overlapped)),

	)

	if r1 == 0 {

		return err

	}

	return nil

}