Cherry-pick #16370 to 7.x: libbeat/common/file: fix fsync fail… (#16417)

On AIX, fsync syscall doesn't work with read-only files.
As os.Open is actually opening in read-only mode, it must be changed
for os.OpenFile with O_RDWR flag.

(cherry picked from commit 81b8fb1)

Co-authored-by: Clément Chigot <[email protected]>

libbeat/common/file/helper_aix.go

@@ -0,0 +1,45 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package file
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// SafeFileRotate safely rotates an existing file under path and replaces it with the tempfile
+func SafeFileRotate(path, tempfile string) error {
+	parent := filepath.Dir(path)
+
+	if e := os.Rename(tempfile, path); e != nil {
+		return e
+	}
+
+	// best-effort fsync on parent directory. The fsync is required by some
+	// filesystems, so to update the parents directory metadata to actually
+	// contain the new file being rotated in.
+	// On AIX, fsync will fail if the file is opened in read-only mode,
+	// which is the case with os.Open.
+	f, err := os.OpenFile(parent, os.O_RDWR, 0)
+	if err != nil {
+		return nil // ignore error
+	}
+	defer f.Close()
+
+	return f.Sync()
+}

libbeat/common/file/helper_other.go

@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-// +build !windows
+// +build !aix,!windows
 
 package file