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// 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))
}
})
}
}
}
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