local: factor PreAllocate and SetSparse to lib/file

backend/local/local.go

@@ -977,7 +977,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 			}
 		}
 		// Pre-allocate the file for performance reasons
-		err = preAllocate(src.Size(), f)
+		err = file.PreAllocate(src.Size(), f)
 		if err != nil {
 			fs.Debugf(o, "Failed to pre-allocate: %v", err)
 		}
@@ -1064,12 +1064,12 @@ func (f *Fs) OpenWriterAt(ctx context.Context, remote string, size int64) (fs.Wr
 		return nil, err
 	}
 	// Pre-allocate the file for performance reasons
-	err = preAllocate(size, out)
+	err = file.PreAllocate(size, out)
 	if err != nil {
 		fs.Debugf(o, "Failed to pre-allocate: %v", err)
 	}
 	// Set the file to be a sparse file (important on Windows)
-	err = setSparse(out)
+	err = file.SetSparse(out)
 	if err != nil {
 		fs.Debugf(o, "Failed to set sparse: %v", err)
 	}

backend/local/preallocate_other.go

@@ -1,15 +0,0 @@
-//+build !windows,!linux
-
-package local
-
-import "os"
-
-// preAllocate the file for performance reasons
-func preAllocate(size int64, out *os.File) error {
-	return nil
-}
-
-// setSparse makes the file be a sparse file
-func setSparse(out *os.File) error {
-	return nil
-}

lib/file/preallocate_other.go

@@ -0,0 +1,15 @@
+//+build !windows,!linux
+
+package file
+
+import "os"
+
+// PreAllocate the file for performance reasons
+func PreAllocate(size int64, out *os.File) error {
+	return nil
+}
+
+// SetSparse makes the file be a sparse file
+func SetSparse(out *os.File) error {
+	return nil
+}

lib/file/preallocate_unix.go

@@ -1,6 +1,6 @@
 //+build linux
 
-package local
+package file
 
 import (
 	"os"
@@ -18,8 +18,8 @@ var (
 	fallocFlagsIndex int32
 )
 
-// preAllocate the file for performance reasons
-func preAllocate(size int64, out *os.File) error {
+// PreAllocate the file for performance reasons
+func PreAllocate(size int64, out *os.File) error {
 	if size <= 0 {
 		return nil
 	}
@@ -45,7 +45,7 @@ again:
 	return err
 }
 
-// setSparse makes the file be a sparse file
-func setSparse(out *os.File) error {
+// SetSparse makes the file be a sparse file
+func SetSparse(out *os.File) error {
 	return nil
 }

lib/file/preallocate_windows.go

@@ -1,6 +1,6 @@
 //+build windows
 
-package local
+package file
 
 import (
 	"os"
@@ -32,8 +32,8 @@ type ioStatusBlock struct {
 	Status, Information uintptr
 }
 
-// preAllocate the file for performance reasons
-func preAllocate(size int64, out *os.File) error {
+// PreAllocate the file for performance reasons
+func PreAllocate(size int64, out *os.File) error {
 	if size <= 0 {
 		return nil
 	}
@@ -82,8 +82,8 @@ const (
 	FSCTL_SET_SPARSE = 0x000900c4
 )
 
-// setSparse makes the file be a sparse file
-func setSparse(out *os.File) error {
+// SetSparse makes the file be a sparse file
+func SetSparse(out *os.File) error {
 	err := syscall.DeviceIoControl(syscall.Handle(out.Fd()), FSCTL_SET_SPARSE, nil, 0, nil, 0, nil, nil)
 	if err != nil {
 		return errors.Wrap(err, "DeviceIoControl FSCTL_SET_SPARSE")