Remove all syscall calls from devicemapper

graphdriver/devmapper/sys.go

@@ -1,15 +1,31 @@
 package devmapper
 
-
 import (
+	"os"
 	"syscall"
 )
 
+type (
+	sysStatT syscall.Stat_t
+	sysErrno syscall.Errno
+)
 
 var (
-	SyscallMount		= syscall.Mount
-	SyscallUnmount		= syscall.Unmount
-	SyscallCloseOnExec	= syscall.CloseOnExec
-	SyscallSyscall		= syscall.Syscall
-	OSOpenFile		= os.OpenFile
+	// functions
+	sysMount       = syscall.Mount
+	sysUnmount     = syscall.Unmount
+	sysCloseOnExec = syscall.CloseOnExec
+	sysSyscall     = syscall.Syscall
+	osOpenFile     = os.OpenFile
 )
+
+const (
+	sysMsMgcVal = syscall.MS_MGC_VAL
+	sysMsRdOnly = syscall.MS_RDONLY
+	sysEInval   = syscall.EINVAL
+	sysSysIoctl = syscall.SYS_IOCTL
+)
+
+func toSysStatT(i interface{}) *sysStatT {
+	return (*sysStatT)(i.(*syscall.Stat_t))
+}