62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
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package vfs
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import (
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"os"
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"golang.org/x/sys/unix"
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)
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func osGetSharedLock(file *os.File) _ErrorCode {
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return osLock(file, unix.LOCK_SH|unix.LOCK_NB, _IOERR_RDLOCK)
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}
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func osGetReservedLock(file *os.File) _ErrorCode {
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rc := osLock(file, unix.LOCK_EX|unix.LOCK_NB, _IOERR_LOCK)
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if rc == _BUSY {
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// The documentation states the lock is upgraded by releasing the previous lock,
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// then acquiring the new lock.
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// This is a race, so return BUSY_SNAPSHOT to ensure the transaction is aborted.
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return _BUSY_SNAPSHOT
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}
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return rc
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}
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func osGetExclusiveLock(file *os.File, state *LockLevel) _ErrorCode {
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if *state >= LOCK_RESERVED {
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return _OK
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}
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return osGetReservedLock(file)
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}
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func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
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rc := osLock(file, unix.LOCK_SH|unix.LOCK_NB, _IOERR_RDLOCK)
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if rc == _BUSY {
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// The documentation states the lock is upgraded by releasing the previous lock,
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// then acquiring the new lock.
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// This is a race, so return IOERR_RDLOCK to ensure the transaction is aborted.
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return _IOERR_RDLOCK
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}
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return _OK
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}
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func osReleaseLock(file *os.File, _ LockLevel) _ErrorCode {
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err := unix.Flock(int(file.Fd()), unix.LOCK_UN)
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if err != nil {
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return _IOERR_UNLOCK
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}
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return _OK
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}
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func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
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// Test the RESERVED lock.
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lock, rc := osTestLock(file, _RESERVED_BYTE, 1)
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return lock == unix.F_WRLCK, rc
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}
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func osLock(file *os.File, how int, def _ErrorCode) _ErrorCode {
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err := unix.Flock(int(file.Fd()), how)
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return osLockErrorCode(err, def)
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}
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