145 lines
2.6 KiB
Go
145 lines
2.6 KiB
Go
//go:build sqlite3_dotlk
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package vfs
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import (
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"errors"
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"io/fs"
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"os"
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"sync"
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)
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var (
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// +checklocks:vfsDotLocksMtx
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vfsDotLocks = map[string]*vfsDotLocker{}
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vfsDotLocksMtx sync.Mutex
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)
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type vfsDotLocker struct {
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shared int // +checklocks:vfsDotLocksMtx
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pending *os.File // +checklocks:vfsDotLocksMtx
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reserved *os.File // +checklocks:vfsDotLocksMtx
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}
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func osGetSharedLock(file *os.File) _ErrorCode {
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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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f, err := os.OpenFile(name+".lock", os.O_RDWR|os.O_CREATE|os.O_EXCL, 0666)
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f.Close()
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if errors.Is(err, fs.ErrExist) {
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return _BUSY // Another process has the lock.
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}
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if err != nil {
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return _IOERR_LOCK
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}
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locker = &vfsDotLocker{}
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vfsDotLocks[name] = locker
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}
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if locker.pending != nil {
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return _BUSY
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}
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locker.shared++
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return _OK
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}
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func osGetReservedLock(file *os.File) _ErrorCode {
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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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return _IOERR_LOCK
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}
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if locker.reserved != nil && locker.reserved != file {
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return _BUSY
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}
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locker.reserved = file
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return _OK
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}
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func osGetExclusiveLock(file *os.File, _ *LockLevel) _ErrorCode {
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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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return _IOERR_LOCK
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}
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if locker.pending != nil && locker.pending != file {
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return _BUSY
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}
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locker.pending = file
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if locker.shared > 1 {
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return _BUSY
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}
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return _OK
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}
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func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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return _IOERR_UNLOCK
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}
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if locker.reserved == file {
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locker.reserved = nil
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}
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if locker.pending == file {
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locker.pending = nil
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}
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return _OK
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}
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func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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return _IOERR_UNLOCK
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}
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if locker.shared == 1 {
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err := os.Remove(name + ".lock")
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if err != nil && !errors.Is(err, fs.ErrNotExist) {
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return _IOERR_UNLOCK
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}
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delete(vfsDotLocks, name)
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}
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if locker.reserved == file {
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locker.reserved = nil
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}
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if locker.pending == file {
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locker.pending = nil
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}
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locker.shared--
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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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vfsDotLocksMtx.Lock()
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defer vfsDotLocksMtx.Unlock()
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name := file.Name()
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locker := vfsDotLocks[name]
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if locker == nil {
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return false, _OK
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}
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return locker.reserved != nil, _OK
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}
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