Full go modules usage

[nncp.git] / src / lockdir.go

diff --git a/src/lockdir.go b/src/lockdir.go
new file mode 100644 (file)
index 0000000..3a9afdc
--- /dev/null
+++ b/src/lockdir.go
@@ -0,0 +1,53 @@
+/*
+NNCP -- Node to Node copy, utilities for store-and-forward data exchange
+Copyright (C) 2016-2019 Sergey Matveev <stargrave@stargrave.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package nncp
+
+import (
+       "os"
+       "path/filepath"
+
+       "golang.org/x/sys/unix"
+)
+
+func (ctx *Ctx) LockDir(nodeId *NodeId, xx TRxTx) (*os.File, error) {
+       ctx.ensureRxDir(nodeId)
+       lockPath := filepath.Join(ctx.Spool, nodeId.String(), string(xx)) + ".lock"
+       dirLock, err := os.OpenFile(
+               lockPath,
+               os.O_CREATE|os.O_WRONLY,
+               os.FileMode(0600),
+       )
+       if err != nil {
+               ctx.LogE("lockdir", SDS{"path": lockPath, "err": err}, "")
+               return nil, err
+       }
+       err = unix.Flock(int(dirLock.Fd()), unix.LOCK_EX|unix.LOCK_NB)
+       if err != nil {
+               ctx.LogE("lockdir", SDS{"path": lockPath, "err": err}, "")
+               dirLock.Close()
+               return nil, err
+       }
+       return dirLock, nil
+}
+
+func (ctx *Ctx) UnlockDir(fd *os.File) {
+       if fd != nil {
+               unix.Flock(int(fd.Fd()), unix.LOCK_UN)
+               fd.Close()
+       }
+}