60 lines
1.6 KiB
Go
60 lines
1.6 KiB
Go
//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_dotlk)
|
|
|
|
package vfs
|
|
|
|
import (
|
|
"os"
|
|
"time"
|
|
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
func osGetSharedLock(file *os.File) _ErrorCode {
|
|
// Test the PENDING lock before acquiring a new SHARED lock.
|
|
if lock, _ := osTestLock(file, _PENDING_BYTE, 1); lock == unix.F_WRLCK {
|
|
return _BUSY
|
|
}
|
|
// Acquire the SHARED lock.
|
|
return osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
|
|
}
|
|
|
|
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 {
|
|
if *state == LOCK_RESERVED {
|
|
// A PENDING lock is needed before acquiring an EXCLUSIVE lock.
|
|
if rc := osWriteLock(file, _PENDING_BYTE, 1, -1); rc != _OK {
|
|
return rc
|
|
}
|
|
*state = LOCK_PENDING
|
|
}
|
|
// Acquire the EXCLUSIVE lock.
|
|
return osWriteLock(file, _SHARED_FIRST, _SHARED_SIZE, time.Millisecond)
|
|
}
|
|
|
|
func osDowngradeLock(file *os.File, state LockLevel) _ErrorCode {
|
|
if state >= LOCK_EXCLUSIVE {
|
|
// Downgrade to a 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.
|
|
return osUnlock(file, _PENDING_BYTE, 2)
|
|
}
|
|
|
|
func osReleaseLock(file *os.File, _ LockLevel) _ErrorCode {
|
|
// Release all locks.
|
|
return osUnlock(file, 0, 0)
|
|
}
|
|
|
|
func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
|
|
// Test the RESERVED lock.
|
|
lock, rc := osTestLock(file, _RESERVED_BYTE, 1)
|
|
return lock == unix.F_WRLCK, rc
|
|
}
|