bump ncruces/go-sqlite3 to v0.20.2 (#3524)

vendor/github.com/ncruces/go-sqlite3/vfs/os_dotlk.go

@@ -0,0 +1,143 @@
+//go:build sqlite3_dotlk
+
+package vfs
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"sync"
+)
+
+var (
+	// +checklocks:vfsDotLocksMtx
+	vfsDotLocks    = map[string]*vfsDotLocker{}
+	vfsDotLocksMtx sync.Mutex
+)
+
+type vfsDotLocker struct {
+	shared   int      // +checklocks:vfsDotLocksMtx
+	pending  *os.File // +checklocks:vfsDotLocksMtx
+	reserved *os.File // +checklocks:vfsDotLocksMtx
+}
+
+func osGetSharedLock(file *os.File) _ErrorCode {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		err := os.Mkdir(name+".lock", 0777)
+		if errors.Is(err, fs.ErrExist) {
+			return _BUSY // Another process has the lock.
+		}
+		if err != nil {
+			return _IOERR_LOCK
+		}
+		locker = &vfsDotLocker{}
+		vfsDotLocks[name] = locker
+	}
+
+	if locker.pending != nil {
+		return _BUSY
+	}
+	locker.shared++
+	return _OK
+}
+
+func osGetReservedLock(file *os.File) _ErrorCode {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		return _IOERR_LOCK
+	}
+
+	if locker.reserved != nil && locker.reserved != file {
+		return _BUSY
+	}
+	locker.reserved = file
+	return _OK
+}
+
+func osGetExclusiveLock(file *os.File, _ *LockLevel) _ErrorCode {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		return _IOERR_LOCK
+	}
+
+	if locker.pending != nil && locker.pending != file {
+		return _BUSY
+	}
+	locker.pending = file
+	if locker.shared > 1 {
+		return _BUSY
+	}
+	return _OK
+}
+
+func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		return _IOERR_UNLOCK
+	}
+
+	if locker.reserved == file {
+		locker.reserved = nil
+	}
+	if locker.pending == file {
+		locker.pending = nil
+	}
+	return _OK
+}
+
+func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		return _IOERR_UNLOCK
+	}
+
+	if locker.shared == 1 {
+		err := os.Remove(name + ".lock")
+		if err != nil && !errors.Is(err, fs.ErrNotExist) {
+			return _IOERR_UNLOCK
+		}
+		delete(vfsDotLocks, name)
+	}
+
+	if locker.reserved == file {
+		locker.reserved = nil
+	}
+	if locker.pending == file {
+		locker.pending = nil
+	}
+	locker.shared--
+	return _OK
+}
+
+func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
+	vfsDotLocksMtx.Lock()
+	defer vfsDotLocksMtx.Unlock()
+
+	name := file.Name()
+	locker := vfsDotLocks[name]
+	if locker == nil {
+		return false, _OK
+	}
+	return locker.reserved != nil, _OK
+}