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_test.go

@@ -0,0 +1,110 @@
+package mount
+
+import (
+	"os"
+	"path"
+	"syscall"
+	"testing"
+)
+
+func TestMountOptionsParsing(t *testing.T) {
+	options := "bind,ro,size=10k"
+
+	flag, data := parseOptions(options)
+
+	if data != "size=10k" {
+		t.Fatalf("Expected size=10 got %s", data)
+	}
+
+	expectedFlag := syscall.MS_BIND | syscall.MS_RDONLY
+
+	if flag != expectedFlag {
+		t.Fatalf("Expected %d got %d", expectedFlag, flag)
+	}
+}
+
+func TestMounted(t *testing.T) {
+	tmp := path.Join(os.TempDir(), "mount-tests")
+	if err := os.MkdirAll(tmp, 0777); err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmp)
+
+	var (
+		sourcePath = path.Join(tmp, "sourcefile.txt")
+		targetPath = path.Join(tmp, "targetfile.txt")
+	)
+
+	f, err := os.Create(sourcePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.WriteString("hello")
+	f.Close()
+
+	f, err = os.Create(targetPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	if err := Mount(sourcePath, targetPath, "none", "bind,rw"); err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := Unmount(targetPath); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	mounted, err := Mounted(targetPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !mounted {
+		t.Fatalf("Expected %s to be mounted", targetPath)
+	}
+	if _, err := os.Stat(targetPath); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestMountReadonly(t *testing.T) {
+	tmp := path.Join(os.TempDir(), "mount-tests")
+	if err := os.MkdirAll(tmp, 0777); err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmp)
+
+	var (
+		sourcePath = path.Join(tmp, "sourcefile.txt")
+		targetPath = path.Join(tmp, "targetfile.txt")
+	)
+
+	f, err := os.Create(sourcePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.WriteString("hello")
+	f.Close()
+
+	f, err = os.Create(targetPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	if err := Mount(sourcePath, targetPath, "none", "bind,ro"); err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := Unmount(targetPath); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	f, err = os.OpenFile(targetPath, os.O_RDWR, 0777)
+	if err == nil {
+		t.Fatal("Should not be able to open a ro file as rw")
+	}
+}