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