60 lines
1.6 KiB
Go
60 lines
1.6 KiB
Go
//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_nosys)
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package vfs
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import (
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"os"
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"time"
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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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// Test the PENDING lock before acquiring a new SHARED lock.
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if lock, _ := osTestLock(file, _PENDING_BYTE, 1); lock == unix.F_WRLCK {
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return _BUSY
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}
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// Acquire the SHARED lock.
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return osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
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}
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func osGetReservedLock(file *os.File) _ErrorCode {
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// Acquire the RESERVED lock.
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return osWriteLock(file, _RESERVED_BYTE, 1, 0)
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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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// A PENDING lock is needed before acquiring an EXCLUSIVE lock.
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if rc := osWriteLock(file, _PENDING_BYTE, 1, -1); rc != _OK {
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return rc
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}
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*state = LOCK_PENDING
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}
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// Acquire the EXCLUSIVE lock.
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return osWriteLock(file, _SHARED_FIRST, _SHARED_SIZE, time.Millisecond)
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}
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func osDowngradeLock(file *os.File, state LockLevel) _ErrorCode {
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if state >= LOCK_EXCLUSIVE {
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// Downgrade to a SHARED lock.
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if rc := osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); rc != _OK {
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// notest // this should never happen
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return _IOERR_RDLOCK
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}
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}
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// Release the PENDING and RESERVED locks.
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return osUnlock(file, _PENDING_BYTE, 2)
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}
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func osReleaseLock(file *os.File, _ LockLevel) _ErrorCode {
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// Release all locks.
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return osUnlock(file, 0, 0)
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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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