Convert memfs into proto-tmpfs.

- Renamed memfs to tmpfs.
- Copied fileRangeSet bits from fs/fsutil/ to fsimpl/tmpfs/
- Changed tmpfs to be backed by filemem instead of byte slice.
- regularFileReadWriter uses a sync.Pool, similar to gofer client.

PiperOrigin-RevId: 288356380

1 files changed, 224 insertions, 0 deletions

diff --git a/pkg/sentry/fsimpl/tmpfs/regular_file_test.go b/pkg/sentry/fsimpl/tmpfs/regular_file_test.go
new file mode 100644
index 000000000..3731c5b6f
--- /dev/null
+++ b/pkg/sentry/fsimpl/tmpfs/regular_file_test.go
@@ -0,0 +1,224 @@
+// 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 tmpfs
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"testing"
+
+	"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/kernel/contexttest"
+	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// newFileFD creates a new file in a new tmpfs mount, and returns the FD. If
+// the returned err is not nil, then cleanup should be called when the FD is no
+// longer needed.
+func newFileFD(ctx context.Context, filename string) (*vfs.FileDescription, func(), error) {
+	creds := auth.CredentialsFromContext(ctx)
+
+	vfsObj := vfs.New()
+	vfsObj.MustRegisterFilesystemType("tmpfs", FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{
+		AllowUserMount: true,
+	})
+	mntns, err := vfsObj.NewMountNamespace(ctx, creds, "", "tmpfs", &vfs.GetFilesystemOptions{})
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to create tmpfs root mount: %v", err)
+	}
+	root := mntns.Root()
+
+	// Create the file that will be write/read.
+	fd, err := vfsObj.OpenAt(ctx, creds, &vfs.PathOperation{
+		Root:               root,
+		Start:              root,
+		Path:               fspath.Parse(filename),
+		FollowFinalSymlink: true,
+	}, &vfs.OpenOptions{
+		Flags: linux.O_RDWR | linux.O_CREAT | linux.O_EXCL,
+		Mode:  0644,
+	})
+	if err != nil {
+		root.DecRef()
+		mntns.DecRef(vfsObj)
+		return nil, nil, fmt.Errorf("failed to create file %q: %v", filename, err)
+	}
+
+	return fd, func() {
+		root.DecRef()
+		mntns.DecRef(vfsObj)
+	}, nil
+}
+
+// Test that we can write some data to a file and read it back.`
+func TestSimpleWriteRead(t *testing.T) {
+	ctx := contexttest.Context(t)
+	fd, cleanup, err := newFileFD(ctx, "simpleReadWrite")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cleanup()
+
+	// Write.
+	data := []byte("foobarbaz")
+	n, err := fd.Write(ctx, usermem.BytesIOSequence(data), vfs.WriteOptions{})
+	if err != nil {
+		t.Fatalf("fd.Write failed: %v", err)
+	}
+	if n != int64(len(data)) {
+		t.Errorf("fd.Write got short write length %d, want %d", n, len(data))
+	}
+	if got, want := fd.Impl().(*regularFileFD).off, int64(len(data)); got != want {
+		t.Errorf("fd.Write left offset at %d, want %d", got, want)
+	}
+
+	// Seek back to beginning.
+	if _, err := fd.Seek(ctx, 0, linux.SEEK_SET); err != nil {
+		t.Fatalf("fd.Seek failed: %v", err)
+	}
+	if got, want := fd.Impl().(*regularFileFD).off, int64(0); got != want {
+		t.Errorf("fd.Seek(0) left offset at %d, want %d", got, want)
+	}
+
+	// Read.
+	buf := make([]byte, len(data))
+	n, err = fd.Read(ctx, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
+	if err != nil && err != io.EOF {
+		t.Fatalf("fd.Read failed: %v", err)
+	}
+	if n != int64(len(data)) {
+		t.Errorf("fd.Read got short read length %d, want %d", n, len(data))
+	}
+	if got, want := string(buf), string(data); got != want {
+		t.Errorf("Read got %q want %s", got, want)
+	}
+	if got, want := fd.Impl().(*regularFileFD).off, int64(len(data)); got != want {
+		t.Errorf("fd.Write left offset at %d, want %d", got, want)
+	}
+}
+
+func TestPWrite(t *testing.T) {
+	ctx := contexttest.Context(t)
+	fd, cleanup, err := newFileFD(ctx, "PRead")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cleanup()
+
+	// Fill file with 1k 'a's.
+	data := bytes.Repeat([]byte{'a'}, 1000)
+	n, err := fd.Write(ctx, usermem.BytesIOSequence(data), vfs.WriteOptions{})
+	if err != nil {
+		t.Fatalf("fd.Write failed: %v", err)
+	}
+	if n != int64(len(data)) {
+		t.Errorf("fd.Write got short write length %d, want %d", n, len(data))
+	}
+
+	// Write "gVisor is awesome" at various offsets.
+	buf := []byte("gVisor is awesome")
+	offsets := []int{0, 1, 2, 10, 20, 50, 100, len(data) - 100, len(data) - 1, len(data), len(data) + 1}
+	for _, offset := range offsets {
+		name := fmt.Sprintf("PWrite offset=%d", offset)
+		t.Run(name, func(t *testing.T) {
+			n, err := fd.PWrite(ctx, usermem.BytesIOSequence(buf), int64(offset), vfs.WriteOptions{})
+			if err != nil {
+				t.Errorf("fd.PWrite got err %v want nil", err)
+			}
+			if n != int64(len(buf)) {
+				t.Errorf("fd.PWrite got %d bytes want %d", n, len(buf))
+			}
+
+			// Update data to reflect expected file contents.
+			if len(data) < offset+len(buf) {
+				data = append(data, make([]byte, (offset+len(buf))-len(data))...)
+			}
+			copy(data[offset:], buf)
+
+			// Read the whole file and compare with data.
+			readBuf := make([]byte, len(data))
+			n, err = fd.PRead(ctx, usermem.BytesIOSequence(readBuf), 0, vfs.ReadOptions{})
+			if err != nil {
+				t.Fatalf("fd.PRead failed: %v", err)
+			}
+			if n != int64(len(data)) {
+				t.Errorf("fd.PRead got short read length %d, want %d", n, len(data))
+			}
+			if got, want := string(readBuf), string(data); got != want {
+				t.Errorf("PRead got %q want %s", got, want)
+			}
+
+		})
+	}
+}
+
+func TestPRead(t *testing.T) {
+	ctx := contexttest.Context(t)
+	fd, cleanup, err := newFileFD(ctx, "PRead")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cleanup()
+
+	// Write 100 sequences of 'gVisor is awesome'.
+	data := bytes.Repeat([]byte("gVisor is awsome"), 100)
+	n, err := fd.Write(ctx, usermem.BytesIOSequence(data), vfs.WriteOptions{})
+	if err != nil {
+		t.Fatalf("fd.Write failed: %v", err)
+	}
+	if n != int64(len(data)) {
+		t.Errorf("fd.Write got short write length %d, want %d", n, len(data))
+	}
+
+	// Read various sizes from various offsets.
+	sizes := []int{0, 1, 2, 10, 20, 50, 100, 1000}
+	offsets := []int{0, 1, 2, 10, 20, 50, 100, 1000, len(data) - 100, len(data) - 1, len(data), len(data) + 1}
+
+	for _, size := range sizes {
+		for _, offset := range offsets {
+			name := fmt.Sprintf("PRead offset=%d size=%d", offset, size)
+			t.Run(name, func(t *testing.T) {
+				var (
+					wantRead []byte
+					wantErr  error
+				)
+				if offset < len(data) {
+					wantRead = data[offset:]
+				} else if size > 0 {
+					wantErr = io.EOF
+				}
+				if offset+size < len(data) {
+					wantRead = wantRead[:size]
+				}
+				buf := make([]byte, size)
+				n, err := fd.PRead(ctx, usermem.BytesIOSequence(buf), int64(offset), vfs.ReadOptions{})
+				if err != wantErr {
+					t.Errorf("fd.PRead got err %v want %v", err, wantErr)
+				}
+				if n != int64(len(wantRead)) {
+					t.Errorf("fd.PRead got %d bytes want %d", n, len(wantRead))
+				}
+				if got := string(buf[:n]); got != string(wantRead) {
+					t.Errorf("fd.PRead got %q want %q", got, string(wantRead))
+				}
+			})
+		}
+	}
+}