Extract mount into pkg.

Mount is self contained and generic, it should be in pkg, to allow other pkg modules to use it.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)

mount/flags_linux.go

@@ -0,0 +1,61 @@
+package mount
+
+import (
+	"strings"
+	"syscall"
+)
+
+// Parse fstab type mount options into mount() flags
+// and device specific data
+func parseOptions(options string) (int, string) {
+	var (
+		flag int
+		data []string
+	)
+
+	flags := map[string]struct {
+		clear bool
+		flag  int
+	}{
+		"defaults":      {false, 0},
+		"ro":            {false, syscall.MS_RDONLY},
+		"rw":            {true, syscall.MS_RDONLY},
+		"suid":          {true, syscall.MS_NOSUID},
+		"nosuid":        {false, syscall.MS_NOSUID},
+		"dev":           {true, syscall.MS_NODEV},
+		"nodev":         {false, syscall.MS_NODEV},
+		"exec":          {true, syscall.MS_NOEXEC},
+		"noexec":        {false, syscall.MS_NOEXEC},
+		"sync":          {false, syscall.MS_SYNCHRONOUS},
+		"async":         {true, syscall.MS_SYNCHRONOUS},
+		"dirsync":       {false, syscall.MS_DIRSYNC},
+		"remount":       {false, syscall.MS_REMOUNT},
+		"mand":          {false, syscall.MS_MANDLOCK},
+		"nomand":        {true, syscall.MS_MANDLOCK},
+		"atime":         {true, syscall.MS_NOATIME},
+		"noatime":       {false, syscall.MS_NOATIME},
+		"diratime":      {true, syscall.MS_NODIRATIME},
+		"nodiratime":    {false, syscall.MS_NODIRATIME},
+		"bind":          {false, syscall.MS_BIND},
+		"rbind":         {false, syscall.MS_BIND | syscall.MS_REC},
+		"relatime":      {false, syscall.MS_RELATIME},
+		"norelatime":    {true, syscall.MS_RELATIME},
+		"strictatime":   {false, syscall.MS_STRICTATIME},
+		"nostrictatime": {true, syscall.MS_STRICTATIME},
+	}
+
+	for _, o := range strings.Split(options, ",") {
+		// If the option does not exist in the flags table then it is a
+		// data value for a specific fs type
+		if f, exists := flags[o]; exists {
+			if f.clear {
+				flag &= ^f.flag
+			} else {
+				flag |= f.flag
+			}
+		} else {
+			data = append(data, o)
+		}
+	}
+	return flag, strings.Join(data, ",")
+}