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//go:build !sqlite3_dotlk
package vfs
import (
"os"
"time"
"golang.org/x/sys/windows"
)
func osReadAt(file *os.File, p []byte, off int64) (int, error) {
return file.ReadAt(p, off)
}
func osWriteAt(file *os.File, p []byte, off int64) (int, error) {
n, err := file.WriteAt(p, off)
if errno, ok := err.(windows.Errno); ok {
switch errno {
case
windows.ERROR_HANDLE_DISK_FULL,
windows.ERROR_DISK_FULL:
return n, sysError{err, _FULL}
}
}
return n, err
}
func osGetSharedLock(file *os.File) error {
// Acquire the PENDING lock temporarily before acquiring a new SHARED lock.
err := osReadLock(file, _PENDING_BYTE, 1, 0)
if err == nil {
// Acquire the SHARED lock.
err = osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
// Release the PENDING lock.
osUnlock(file, _PENDING_BYTE, 1)
}
return err
}
func osGetReservedLock(file *os.File) error {
// Acquire the RESERVED lock.
return osWriteLock(file, _RESERVED_BYTE, 1, 0)
}
func osGetExclusiveLock(file *os.File, state *LockLevel) error {
// A PENDING lock is needed before releasing the SHARED lock.
if *state < LOCK_PENDING {
// If we were RESERVED, we can block indefinitely.
var timeout time.Duration
if *state == LOCK_RESERVED {
timeout = -1
}
if err := osWriteLock(file, _PENDING_BYTE, 1, timeout); err != nil {
return err
}
*state = LOCK_PENDING
}
// Release the SHARED lock.
osUnlock(file, _SHARED_FIRST, _SHARED_SIZE)
// Acquire the EXCLUSIVE lock.
// Can't wait here, because the file is not OVERLAPPED.
err := osWriteLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
if err != nil {
// Reacquire the SHARED lock.
if err := osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); err != nil {
// notest // this should never happen
return _IOERR_RDLOCK
}
}
return err
}
func osDowngradeLock(file *os.File, state LockLevel) error {
if state >= LOCK_EXCLUSIVE {
// Release the EXCLUSIVE lock while holding the PENDING lock.
osUnlock(file, _SHARED_FIRST, _SHARED_SIZE)
// Reacquire the SHARED lock.
if err := osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); err != nil {
// notest // this should never happen
return _IOERR_RDLOCK
}
}
// Release the PENDING and RESERVED locks.
if state >= LOCK_RESERVED {
osUnlock(file, _RESERVED_BYTE, 1)
}
if state >= LOCK_PENDING {
osUnlock(file, _PENDING_BYTE, 1)
}
return nil
}
func osReleaseLock(file *os.File, state LockLevel) error {
// Release all locks, PENDING must be last.
if state >= LOCK_RESERVED {
osUnlock(file, _RESERVED_BYTE, 1)
}
if state >= LOCK_SHARED {
osUnlock(file, _SHARED_FIRST, _SHARED_SIZE)
}
if state >= LOCK_PENDING {
osUnlock(file, _PENDING_BYTE, 1)
}
return nil
}
func osCheckReservedLock(file *os.File) (bool, error) {
// Test the RESERVED lock.
err := osLock(file, 0, _RESERVED_BYTE, 1, 0, _IOERR_CHECKRESERVEDLOCK)
if err == _BUSY {
return true, nil
}
if err == nil {
// Release the RESERVED lock.
osUnlock(file, _RESERVED_BYTE, 1)
return false, nil
}
return false, err
}
func osReadLock(file *os.File, start, len uint32, timeout time.Duration) error {
return osLock(file, 0, start, len, timeout, _IOERR_RDLOCK)
}
func osWriteLock(file *os.File, start, len uint32, timeout time.Duration) error {
return osLock(file, windows.LOCKFILE_EXCLUSIVE_LOCK, start, len, timeout, _IOERR_LOCK)
}
func osLock(file *os.File, flags, start, len uint32, timeout time.Duration, def _ErrorCode) error {
var err error
switch {
default:
err = osLockEx(file, flags|windows.LOCKFILE_FAIL_IMMEDIATELY, start, len)
case timeout < 0:
err = osLockEx(file, flags, start, len)
}
return osLockErrorCode(err, def)
}
func osUnlock(file *os.File, start, len uint32) error {
err := windows.UnlockFileEx(windows.Handle(file.Fd()),
0, len, 0, &windows.Overlapped{Offset: start})
if err == windows.ERROR_NOT_LOCKED {
return nil
}
if err != nil {
return sysError{err, _IOERR_UNLOCK}
}
return nil
}
func osLockEx(file *os.File, flags, start, len uint32) error {
return windows.LockFileEx(windows.Handle(file.Fd()), flags,
0, len, 0, &windows.Overlapped{Offset: start})
}
func osLockErrorCode(err error, def _ErrorCode) error {
if err == nil {
return nil
}
if errno, ok := err.(windows.Errno); ok {
// https://devblogs.microsoft.com/oldnewthing/20140905-00/?p=63
switch errno {
case
windows.ERROR_LOCK_VIOLATION,
windows.ERROR_OPERATION_ABORTED,
windows.ERROR_IO_PENDING,
windows.WAIT_TIMEOUT:
return _BUSY
}
}
return sysError{err, def}
}
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