make locking work on windows (#46)

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## pg_back 2.0.1
 
 * Use /var/run/postgresql as default host for connections
+* Support Windows
 
 ## pg_back 2.0.0
 

lock.go

@@ -23,6 +23,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// +build !windows
+
 package main
 
 import (

lock_win.go

@@ -0,0 +1,66 @@
+// pg_back
+//
+// Copyright 2011-2021 Nicolas Thauvin and contributors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//  1. Redistributions of source code must retain the above copyright
+//     notice, this list of conditions and the following disclaimer.
+//  2. Redistributions in binary form must reproduce the above copyright
+//     notice, this list of conditions and the following disclaimer in the
+//     documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
+// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+// IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// +build windows
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// lockPath on windows just creates a file without locking, it only tests if
+// the file exist to consider it locked
+func lockPath(path string) (*os.File, bool, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return nil, false, err
+	}
+
+	info, err := os.Stat(path)
+	if err == nil {
+		if info.IsDir() {
+			return nil, false, &os.PathError{Op: "stat", Path: path, Err: fmt.Errorf("unexpected directory")}
+		}
+		return nil, false, err
+	}
+
+	l.Verboseln("creating lock file", path)
+	f, err := os.Create(path)
+	if err != nil {
+		return nil, false, err
+	}
+	return f, true, nil
+}
+
+// unlockPath releases the lock from the open file and removes the
+// underlying path
+func unlockPath(f *os.File) error {
+	path := f.Name()
+	l.Verboseln("removing lock file", path)
+	f.Close()
+	return os.Remove(path)
+}