Make -x/--one-file-system compile under Windows and add docs

local/read_device_unix.go

@@ -0,0 +1,31 @@
+// Device reading functions
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package local
+
+import (
+	"os"
+	"syscall"
+
+	"github.com/ncw/rclone/fs"
+	"github.com/spf13/pflag"
+)
+
+var (
+	oneFileSystem = pflag.BoolP("one-file-system", "x", false, "Don't cross filesystem boundaries.")
+)
+
+// readDevice turns a valid os.FileInfo into a device number,
+// returning devUnset if it fails.
+func readDevice(fi os.FileInfo) uint64 {
+	if !*oneFileSystem {
+		return devUnset
+	}
+	statT, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		fs.Debug(fi.Name(), "Type assertion fi.Sys().(*syscall.Stat_t) failed from: %#v", fi.Sys())
+		return devUnset
+	}
+	return uint64(statT.Dev)
+}