virtcontainers: Keep all filesystem sharing prep code to sandbox.go

With the Linux implementation of the FilesystemSharer interface, we can
now remove all host filesystem sharing code from kata_agent and keep it
where it belongs: sandbox.go.

Signed-off-by: Samuel Ortiz <s.ortiz@apple.com>

src/runtime/virtcontainers/fs_share_linux_test.go

@@ -0,0 +1,102 @@
+// Copyright (c) 2018 Intel Corporation
+// Copyright (c) 2022 Apple Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package virtcontainers
+
+import (
+	"context"
+	"os"
+	"path"
+	"path/filepath"
+	"syscall"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSandboxSharedFilesystem(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("Test disabled as requires root user")
+	}
+
+	assert := assert.New(t)
+	// create temporary files to mount:
+	testMountPath, err := os.MkdirTemp("", "sandbox-test")
+	assert.NoError(err)
+	defer os.RemoveAll(testMountPath)
+
+	// create a new shared directory for our test:
+	kataHostSharedDirSaved := kataHostSharedDir
+	testHostDir, err := os.MkdirTemp("", "kata-Cleanup")
+	assert.NoError(err)
+	kataHostSharedDir = func() string {
+		return testHostDir
+	}
+	defer func() {
+		kataHostSharedDir = kataHostSharedDirSaved
+	}()
+
+	m1Path := filepath.Join(testMountPath, "foo.txt")
+	f1, err := os.Create(m1Path)
+	assert.NoError(err)
+	defer f1.Close()
+
+	m2Path := filepath.Join(testMountPath, "bar.txt")
+	f2, err := os.Create(m2Path)
+	assert.NoError(err)
+	defer f2.Close()
+
+	// create sandbox for mounting into
+	sandbox := &Sandbox{
+		ctx: context.Background(),
+		id:  "foobar",
+		config: &SandboxConfig{
+			SandboxBindMounts: []string{m1Path, m2Path},
+		},
+	}
+
+	fsShare, err := NewFilesystemShare(sandbox)
+	assert.Nil(err)
+	sandbox.fsShare = fsShare
+
+	// make the shared directory for our test:
+	dir := kataHostSharedDir()
+	err = os.MkdirAll(path.Join(dir, sandbox.id), 0777)
+	assert.Nil(err)
+	defer os.RemoveAll(dir)
+
+	// Test the prepare function. We expect it to succeed
+	err = sandbox.fsShare.Prepare(sandbox.ctx)
+	assert.NoError(err)
+
+	// Test the Cleanup function. We expect it to succeed for the mount to be removed.
+	err = sandbox.fsShare.Cleanup(sandbox.ctx)
+	assert.NoError(err)
+
+	// After successful Cleanup, verify there are not any mounts left behind.
+	stat := syscall.Stat_t{}
+	mount1CheckPath := filepath.Join(getMountPath(sandbox.id), sandboxMountsDir, filepath.Base(m1Path))
+	err = syscall.Stat(mount1CheckPath, &stat)
+	assert.Error(err)
+	assert.True(os.IsNotExist(err))
+
+	mount2CheckPath := filepath.Join(getMountPath(sandbox.id), sandboxMountsDir, filepath.Base(m2Path))
+	err = syscall.Stat(mount2CheckPath, &stat)
+	assert.Error(err)
+	assert.True(os.IsNotExist(err))
+
+	// Verify that Prepare is idempotent.
+	err = sandbox.fsShare.Prepare(sandbox.ctx)
+	assert.NoError(err)
+	err = sandbox.fsShare.Prepare(sandbox.ctx)
+	assert.NoError(err)
+
+	// Verify that Cleanup is idempotent.
+	err = sandbox.fsShare.Cleanup(sandbox.ctx)
+	assert.NoError(err)
+	err = sandbox.fsShare.Cleanup(sandbox.ctx)
+	assert.NoError(err)
+}