fix: use copy when a rename spans volumes (#23785)

When a file rename fails with EXDEV
(cross device or volume error), copy the
file and delete the original instead

Differs from master branch by overwriting
existing files instead of erring.

closes #22997

pkg/file/file_unix.go

@@ -3,8 +3,13 @@
 package file
 
 import (
+	"errors"
+	"fmt"
+	"io"
 	"os"
 	"syscall"
+
+	errors2 "github.com/influxdata/influxdb/pkg/errors"
 )
 
 func SyncDir(dirName string) error {
@@ -29,7 +34,62 @@ func SyncDir(dirName string) error {
 	return dir.Close()
 }
 
-// RenameFile will rename the source to target using os function.
+// RenameFileWithReplacement will replace any existing file at newpath with the contents
+// of oldpath. It works also if it the rename spans over several file systems.
+//
+// If no file already exists at newpath, newpath will be created using the contents
+// of oldpath. If this function returns successfully, the contents of newpath will
+// be identical to oldpath, and oldpath will be removed.
+func RenameFileWithReplacement(oldpath, newpath string) error {
+	if err := os.Rename(oldpath, newpath); !errors.Is(err, syscall.EXDEV) {
+		// note: also includes err == nil
+		return err
+	}
+
+	// move over filesystem boundaries, we have to copy.
+	// (if there was another error, it will likely fail a second time)
+	return MoveFileWithReplacement(oldpath, newpath)
+
+}
+
+// RenameFile renames oldpath to newpath, returning an error if newpath already
+// exists. If this function returns successfully, the contents of newpath will
+// be identical to oldpath, and oldpath will be removed.
 func RenameFile(oldpath, newpath string) error {
-	return os.Rename(oldpath, newpath)
+	return RenameFileWithReplacement(oldpath, newpath)
+}
+
+func copyFile(src, dst string) (err error) {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+
+	defer errors2.Capture(&err, out.Close)()
+
+	defer errors2.Capture(&err, in.Close)()
+
+	if _, err = io.Copy(out, in); err != nil {
+		return err
+	}
+
+	return out.Sync()
+}
+
+// MoveFileWithReplacement copies the file contents at `src` to `dst`.
+// and deletes `src` on success.
+//
+// If the file at `dst` already exists, it will be truncated and its contents
+// overwritten.
+func MoveFileWithReplacement(src, dst string) error {
+	if err := copyFile(src, dst); err != nil {
+		return fmt.Errorf("copy: %w", err)
+	}
+
+	return os.Remove(src)
 }