1 files changed, 281 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/testutil/testutil.go b/pkg/sentry/fsimpl/testutil/testutil.go
new file mode 100644
index 000000000..2a723a89f
--- /dev/null
+++ b/pkg/sentry/fsimpl/testutil/testutil.go
@@ -0,0 +1,281 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package testutil provides common test utilities for kernfs-based
+// filesystems.
+package testutil
+
+import (
+	"fmt"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/sync"
+)
+
+// System represents the context for a single test.
+//
+// Test systems must be explicitly destroyed with System.Destroy.
+type System struct {
+	t     *testing.T
+	Ctx   context.Context
+	Creds *auth.Credentials
+	VFS   *vfs.VirtualFilesystem
+	Root  vfs.VirtualDentry
+	mns   *vfs.MountNamespace
+}
+
+// NewSystem constructs a System.
+//
+// Precondition: Caller must hold a reference on mns, whose ownership
+// is transferred to the new System.
+func NewSystem(ctx context.Context, t *testing.T, v *vfs.VirtualFilesystem, mns *vfs.MountNamespace) *System {
+	s := &System{
+		t:     t,
+		Ctx:   ctx,
+		Creds: auth.CredentialsFromContext(ctx),
+		VFS:   v,
+		mns:   mns,
+		Root:  mns.Root(),
+	}
+	return s
+}
+
+// WithSubtest creates a temporary test system with a new test harness,
+// referencing all other resources from the original system. This is useful when
+// a system is reused for multiple subtests, and the T needs to change for each
+// case. Note that this is safe when test cases run in parallel, as all
+// resources referenced by the system are immutable, or handle interior
+// mutations in a thread-safe manner.
+//
+// The returned system must not outlive the original and should not be destroyed
+// via System.Destroy.
+func (s *System) WithSubtest(t *testing.T) *System {
+	return &System{
+		t:     t,
+		Ctx:   s.Ctx,
+		Creds: s.Creds,
+		VFS:   s.VFS,
+		mns:   s.mns,
+		Root:  s.Root,
+	}
+}
+
+// WithTemporaryContext constructs a temporary test system with a new context
+// ctx. The temporary system borrows all resources and references from the
+// original system. The returned temporary system must not outlive the original
+// system, and should not be destroyed via System.Destroy.
+func (s *System) WithTemporaryContext(ctx context.Context) *System {
+	return &System{
+		t:     s.t,
+		Ctx:   ctx,
+		Creds: s.Creds,
+		VFS:   s.VFS,
+		mns:   s.mns,
+		Root:  s.Root,
+	}
+}
+
+// Destroy release resources associated with a test system.
+func (s *System) Destroy() {
+	s.Root.DecRef()
+	s.mns.DecRef(s.VFS) // Reference on mns passed to NewSystem.
+}
+
+// ReadToEnd reads the contents of fd until EOF to a string.
+func (s *System) ReadToEnd(fd *vfs.FileDescription) (string, error) {
+	buf := make([]byte, usermem.PageSize)
+	bufIOSeq := usermem.BytesIOSequence(buf)
+	opts := vfs.ReadOptions{}
+
+	var content strings.Builder
+	for {
+		n, err := fd.Read(s.Ctx, bufIOSeq, opts)
+		if n == 0 || err != nil {
+			if err == io.EOF {
+				err = nil
+			}
+			return content.String(), err
+		}
+		content.Write(buf[:n])
+	}
+}
+
+// PathOpAtRoot constructs a PathOperation with the given path from
+// the root of the filesystem.
+func (s *System) PathOpAtRoot(path string) *vfs.PathOperation {
+	return &vfs.PathOperation{
+		Root:  s.Root,
+		Start: s.Root,
+		Path:  fspath.Parse(path),
+	}
+}
+
+// GetDentryOrDie attempts to resolve a dentry referred to by the
+// provided path operation. If unsuccessful, the test fails.
+func (s *System) GetDentryOrDie(pop *vfs.PathOperation) vfs.VirtualDentry {
+	vd, err := s.VFS.GetDentryAt(s.Ctx, s.Creds, pop, &vfs.GetDentryOptions{})
+	if err != nil {
+		s.t.Fatalf("GetDentryAt(pop:%+v) failed: %v", pop, err)
+	}
+	return vd
+}
+
+// DirentType is an alias for values for linux_dirent64.d_type.
+type DirentType = uint8
+
+// ListDirents lists the Dirents for a directory at pop.
+func (s *System) ListDirents(pop *vfs.PathOperation) *DirentCollector {
+	fd, err := s.VFS.OpenAt(s.Ctx, s.Creds, pop, &vfs.OpenOptions{Flags: linux.O_RDONLY})
+	if err != nil {
+		s.t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
+	}
+	defer fd.DecRef()
+
+	collector := &DirentCollector{}
+	if err := fd.IterDirents(s.Ctx, collector); err != nil {
+		s.t.Fatalf("IterDirent failed: %v", err)
+	}
+	return collector
+}
+
+// AssertAllDirentTypes verifies that the set of dirents in collector contains
+// exactly the specified set of expected entries. AssertAllDirentTypes respects
+// collector.skipDots, and implicitly checks for "." and ".." accordingly.
+func (s *System) AssertAllDirentTypes(collector *DirentCollector, expected map[string]DirentType) {
+	// Also implicitly check for "." and "..", if enabled.
+	if !collector.skipDots {
+		expected["."] = linux.DT_DIR
+		expected[".."] = linux.DT_DIR
+	}
+
+	dentryTypes := make(map[string]DirentType)
+	collector.mu.Lock()
+	for _, dirent := range collector.dirents {
+		dentryTypes[dirent.Name] = dirent.Type
+	}
+	collector.mu.Unlock()
+	if diff := cmp.Diff(expected, dentryTypes); diff != "" {
+		s.t.Fatalf("IterDirent had unexpected results:\n--- want\n+++ got\n%v", diff)
+	}
+}
+
+// AssertDirentOffsets verifies that collector contains at least the entries
+// specified in expected, with the given NextOff field. Entries specified in
+// expected but missing from collector result in failure. Extra entries in
+// collector are ignored. AssertDirentOffsets respects collector.skipDots, and
+// implicitly checks for "." and ".." accordingly.
+func (s *System) AssertDirentOffsets(collector *DirentCollector, expected map[string]int64) {
+	// Also implicitly check for "." and "..", if enabled.
+	if !collector.skipDots {
+		expected["."] = 1
+		expected[".."] = 2
+	}
+
+	dentryNextOffs := make(map[string]int64)
+	collector.mu.Lock()
+	for _, dirent := range collector.dirents {
+		// Ignore extra entries in dentries that are not in expected.
+		if _, ok := expected[dirent.Name]; ok {
+			dentryNextOffs[dirent.Name] = dirent.NextOff
+		}
+	}
+	collector.mu.Unlock()
+	if diff := cmp.Diff(expected, dentryNextOffs); diff != "" {
+		s.t.Fatalf("IterDirent had unexpected results:\n--- want\n+++ got\n%v", diff)
+	}
+}
+
+// DirentCollector provides an implementation for vfs.IterDirentsCallback for
+// testing. It simply iterates to the end of a given directory FD and collects
+// all dirents emitted by the callback.
+type DirentCollector struct {
+	mu      sync.Mutex
+	order   []*vfs.Dirent
+	dirents map[string]*vfs.Dirent
+	// When the collector is used in various Assert* functions, should "." and
+	// ".." be implicitly checked?
+	skipDots bool
+}
+
+// SkipDotsChecks enables or disables the implicit checks on "." and ".." when
+// the collector is used in various Assert* functions. Note that "." and ".."
+// are still collected if passed to d.Handle, so the caller should only disable
+// the checks when they aren't expected.
+func (d *DirentCollector) SkipDotsChecks(value bool) {
+	d.skipDots = value
+}
+
+// Handle implements vfs.IterDirentsCallback.Handle.
+func (d *DirentCollector) Handle(dirent vfs.Dirent) bool {
+	d.mu.Lock()
+	if d.dirents == nil {
+		d.dirents = make(map[string]*vfs.Dirent)
+	}
+	d.order = append(d.order, &dirent)
+	d.dirents[dirent.Name] = &dirent
+	d.mu.Unlock()
+	return true
+}
+
+// Count returns the number of dirents currently in the collector.
+func (d *DirentCollector) Count() int {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	return len(d.dirents)
+}
+
+// Contains checks whether the collector has a dirent with the given name and
+// type.
+func (d *DirentCollector) Contains(name string, typ uint8) error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	dirent, ok := d.dirents[name]
+	if !ok {
+		return fmt.Errorf("No dirent named %q found", name)
+	}
+	if dirent.Type != typ {
+		return fmt.Errorf("Dirent named %q found, but was expecting type %s, got: %+v", name, linux.DirentType.Parse(uint64(typ)), dirent)
+	}
+	return nil
+}
+
+// Dirents returns all dirents discovered by this collector.
+func (d *DirentCollector) Dirents() map[string]*vfs.Dirent {
+	d.mu.Lock()
+	dirents := make(map[string]*vfs.Dirent)
+	for n, d := range d.dirents {
+		dirents[n] = d
+	}
+	d.mu.Unlock()
+	return dirents
+}
+
+// OrderedDirents returns an ordered list of dirents as discovered by this
+// collector.
+func (d *DirentCollector) OrderedDirents() []*vfs.Dirent {
+	d.mu.Lock()
+	dirents := make([]*vfs.Dirent, len(d.order))
+	copy(dirents, d.order)
+	d.mu.Unlock()
+	return dirents
+}