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gotosocial/vendor/github.com/ncruces/go-sqlite3/vfs/os_windows.go

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4.2 KiB
Go

//go:build !(sqlite3_dotlk || sqlite3_nosys)
package vfs
import (
"math/rand"
"os"
"time"
"golang.org/x/sys/windows"
)
func osGetSharedLock(file *os.File) _ErrorCode {
// Acquire the PENDING lock temporarily before acquiring a new SHARED lock.
rc := osReadLock(file, _PENDING_BYTE, 1, 0)
if rc == _OK {
// Acquire the SHARED lock.
rc = osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
// Release the PENDING lock.
osUnlock(file, _PENDING_BYTE, 1)
}
return rc
}
func osGetReservedLock(file *os.File) _ErrorCode {
// Acquire the RESERVED lock.
return osWriteLock(file, _RESERVED_BYTE, 1, 0)
}
func osGetExclusiveLock(file *os.File, state *LockLevel) _ErrorCode {
// 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 rc := osWriteLock(file, _PENDING_BYTE, 1, timeout); rc != _OK {
return rc
}
*state = LOCK_PENDING
}
// Release the SHARED lock.
osUnlock(file, _SHARED_FIRST, _SHARED_SIZE)
// Acquire the EXCLUSIVE lock.
rc := osWriteLock(file, _SHARED_FIRST, _SHARED_SIZE, time.Millisecond)
if rc != _OK {
// Reacquire the SHARED lock.
osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
}
return rc
}
func osDowngradeLock(file *os.File, state LockLevel) _ErrorCode {
if state >= LOCK_EXCLUSIVE {
// Release the EXCLUSIVE lock.
osUnlock(file, _SHARED_FIRST, _SHARED_SIZE)
// Reacquire the SHARED lock.
if rc := osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); rc != _OK {
// 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 _OK
}
func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
// Release all locks.
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 _OK
}
func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
// Test the RESERVED lock.
rc := osLock(file, 0, _RESERVED_BYTE, 1, 0, _IOERR_CHECKRESERVEDLOCK)
if rc == _BUSY {
return true, _OK
}
if rc == _OK {
// Release the RESERVED lock.
osUnlock(file, _RESERVED_BYTE, 1)
}
return false, rc
}
func osUnlock(file *os.File, start, len uint32) _ErrorCode {
err := windows.UnlockFileEx(windows.Handle(file.Fd()),
0, len, 0, &windows.Overlapped{Offset: start})
if err == windows.ERROR_NOT_LOCKED {
return _OK
}
if err != nil {
return _IOERR_UNLOCK
}
return _OK
}
func osLock(file *os.File, flags, start, len uint32, timeout time.Duration, def _ErrorCode) _ErrorCode {
var err error
switch {
case timeout == 0:
err = osLockEx(file, flags|windows.LOCKFILE_FAIL_IMMEDIATELY, start, len)
case timeout < 0:
err = osLockEx(file, flags, start, len)
default:
before := time.Now()
for {
err = osLockEx(file, flags|windows.LOCKFILE_FAIL_IMMEDIATELY, start, len)
if errno, _ := err.(windows.Errno); errno != windows.ERROR_LOCK_VIOLATION {
break
}
if time.Since(before) > timeout {
break
}
const sleepIncrement = 1024*1024 - 1 // power of two, ~1ms
time.Sleep(time.Duration(rand.Int63() & sleepIncrement))
}
}
return osLockErrorCode(err, def)
}
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 osReadLock(file *os.File, start, len uint32, timeout time.Duration) _ErrorCode {
return osLock(file, 0, start, len, timeout, _IOERR_RDLOCK)
}
func osWriteLock(file *os.File, start, len uint32, timeout time.Duration) _ErrorCode {
return osLock(file, windows.LOCKFILE_EXCLUSIVE_LOCK, start, len, timeout, _IOERR_LOCK)
}
func osLockErrorCode(err error, def _ErrorCode) _ErrorCode {
if err == nil {
return _OK
}
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_IO_PENDING,
windows.ERROR_OPERATION_ABORTED:
return _BUSY
}
}
return def
}