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/mount.go

@@ -0,0 +1,67 @@
+package mount
+
+import (
+	"time"
+)
+
+func GetMounts() ([]*MountInfo, error) {
+	return parseMountTable()
+}
+
+// Looks at /proc/self/mountinfo to determine of the specified
+// mountpoint has been mounted
+func Mounted(mountpoint string) (bool, error) {
+	entries, err := parseMountTable()
+	if err != nil {
+		return false, err
+	}
+
+	// Search the table for the mountpoint
+	for _, e := range entries {
+		if e.Mountpoint == mountpoint {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+// Mount the specified options at the target path only if
+// the target is not mounted
+// Options must be specified as fstab style
+func Mount(device, target, mType, options string) error {
+	if mounted, err := Mounted(target); err != nil || mounted {
+		return err
+	}
+	return ForceMount(device, target, mType, options)
+}
+
+// Mount the specified options at the target path
+// reguardless if the target is mounted or not
+// Options must be specified as fstab style
+func ForceMount(device, target, mType, options string) error {
+	flag, data := parseOptions(options)
+	if err := mount(device, target, mType, uintptr(flag), data); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Unmount the target only if it is mounted
+func Unmount(target string) error {
+	if mounted, err := Mounted(target); err != nil || !mounted {
+		return err
+	}
+	return ForceUnmount(target)
+}
+
+// Unmount the target reguardless if it is mounted or not
+func ForceUnmount(target string) (err error) {
+	// Simple retry logic for unmount
+	for i := 0; i < 10; i++ {
+		if err = unmount(target, 0); err == nil {
+			return nil
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	return
+}