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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 vfs
import (
"bytes"
"fmt"
"io"
"sync/atomic"
"testing"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/contexttest"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
// fileDescription is the common fd struct which a filesystem implementation
// embeds in all of its file description implementations as required.
type fileDescription struct {
vfsfd FileDescription
FileDescriptionDefaultImpl
}
// genCount contains the number of times its DynamicBytesSource.Generate()
// implementation has been called.
type genCount struct {
count uint64 // accessed using atomic memory ops
}
// Generate implements DynamicBytesSource.Generate.
func (g *genCount) Generate(ctx context.Context, buf *bytes.Buffer) error {
fmt.Fprintf(buf, "%d", atomic.AddUint64(&g.count, 1))
return nil
}
type storeData struct {
data string
}
var _ WritableDynamicBytesSource = (*storeData)(nil)
// Generate implements DynamicBytesSource.
func (d *storeData) Generate(ctx context.Context, buf *bytes.Buffer) error {
buf.WriteString(d.data)
return nil
}
// Generate implements WritableDynamicBytesSource.
func (d *storeData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
buf := make([]byte, src.NumBytes())
n, err := src.CopyIn(ctx, buf)
if err != nil {
return 0, err
}
d.data = string(buf[:n])
return 0, nil
}
// testFD is a read-only FileDescriptionImpl representing a regular file.
type testFD struct {
fileDescription
DynamicBytesFileDescriptionImpl
data DynamicBytesSource
}
func newTestFD(vfsObj *VirtualFilesystem, statusFlags uint32, data DynamicBytesSource) *FileDescription {
vd := vfsObj.NewAnonVirtualDentry("genCountFD")
defer vd.DecRef()
var fd testFD
fd.vfsfd.Init(&fd, statusFlags, vd.Mount(), vd.Dentry(), &FileDescriptionOptions{})
fd.DynamicBytesFileDescriptionImpl.SetDataSource(data)
return &fd.vfsfd
}
// Release implements FileDescriptionImpl.Release.
func (fd *testFD) Release() {
}
// SetStatusFlags implements FileDescriptionImpl.SetStatusFlags.
// Stat implements FileDescriptionImpl.Stat.
func (fd *testFD) Stat(ctx context.Context, opts StatOptions) (linux.Statx, error) {
// Note that Statx.Mask == 0 in the return value.
return linux.Statx{}, nil
}
// SetStat implements FileDescriptionImpl.SetStat.
func (fd *testFD) SetStat(ctx context.Context, opts SetStatOptions) error {
return syserror.EPERM
}
func TestGenCountFD(t *testing.T) {
ctx := contexttest.Context(t)
vfsObj := New() // vfs.New()
fd := newTestFD(vfsObj, linux.O_RDWR, &genCount{})
defer fd.DecRef()
// The first read causes Generate to be called to fill the FD's buffer.
buf := make([]byte, 2)
ioseq := usermem.BytesIOSequence(buf)
n, err := fd.Read(ctx, ioseq, ReadOptions{})
if n != 1 || (err != nil && err != io.EOF) {
t.Fatalf("first Read: got (%d, %v), wanted (1, nil or EOF)", n, err)
}
if want := byte('1'); buf[0] != want {
t.Errorf("first Read: got byte %c, wanted %c", buf[0], want)
}
// A second read without seeking is still at EOF.
n, err = fd.Read(ctx, ioseq, ReadOptions{})
if n != 0 || err != io.EOF {
t.Fatalf("second Read: got (%d, %v), wanted (0, EOF)", n, err)
}
// Seeking to the beginning of the file causes it to be regenerated.
n, err = fd.Seek(ctx, 0, linux.SEEK_SET)
if n != 0 || err != nil {
t.Fatalf("Seek: got (%d, %v), wanted (0, nil)", n, err)
}
n, err = fd.Read(ctx, ioseq, ReadOptions{})
if n != 1 || (err != nil && err != io.EOF) {
t.Fatalf("Read after Seek: got (%d, %v), wanted (1, nil or EOF)", n, err)
}
if want := byte('2'); buf[0] != want {
t.Errorf("Read after Seek: got byte %c, wanted %c", buf[0], want)
}
// PRead at the beginning of the file also causes it to be regenerated.
n, err = fd.PRead(ctx, ioseq, 0, ReadOptions{})
if n != 1 || (err != nil && err != io.EOF) {
t.Fatalf("PRead: got (%d, %v), wanted (1, nil or EOF)", n, err)
}
if want := byte('3'); buf[0] != want {
t.Errorf("PRead: got byte %c, wanted %c", buf[0], want)
}
// Write and PWrite fails.
if _, err := fd.Write(ctx, ioseq, WriteOptions{}); err != syserror.EINVAL {
t.Errorf("Write: got err %v, wanted %v", err, syserror.EINVAL)
}
if _, err := fd.PWrite(ctx, ioseq, 0, WriteOptions{}); err != syserror.EINVAL {
t.Errorf("Write: got err %v, wanted %v", err, syserror.EINVAL)
}
}
func TestWritable(t *testing.T) {
ctx := contexttest.Context(t)
vfsObj := New() // vfs.New()
fd := newTestFD(vfsObj, linux.O_RDWR, &storeData{data: "init"})
defer fd.DecRef()
buf := make([]byte, 10)
ioseq := usermem.BytesIOSequence(buf)
if n, err := fd.Read(ctx, ioseq, ReadOptions{}); n != 4 && err != io.EOF {
t.Fatalf("Read: got (%v, %v), wanted (4, EOF)", n, err)
}
if want := "init"; want == string(buf) {
t.Fatalf("Read: got %v, wanted %v", string(buf), want)
}
// Test PWrite.
want := "write"
writeIOSeq := usermem.BytesIOSequence([]byte(want))
if n, err := fd.PWrite(ctx, writeIOSeq, 0, WriteOptions{}); int(n) != len(want) && err != nil {
t.Errorf("PWrite: got err (%v, %v), wanted (%v, nil)", n, err, len(want))
}
if n, err := fd.PRead(ctx, ioseq, 0, ReadOptions{}); int(n) != len(want) && err != io.EOF {
t.Fatalf("PRead: got (%v, %v), wanted (%v, EOF)", n, err, len(want))
}
if want == string(buf) {
t.Fatalf("PRead: got %v, wanted %v", string(buf), want)
}
// Test Seek to 0 followed by Write.
want = "write2"
writeIOSeq = usermem.BytesIOSequence([]byte(want))
if n, err := fd.Seek(ctx, 0, linux.SEEK_SET); n != 0 && err != nil {
t.Errorf("Seek: got err (%v, %v), wanted (0, nil)", n, err)
}
if n, err := fd.Write(ctx, writeIOSeq, WriteOptions{}); int(n) != len(want) && err != nil {
t.Errorf("Write: got err (%v, %v), wanted (%v, nil)", n, err, len(want))
}
if n, err := fd.PRead(ctx, ioseq, 0, ReadOptions{}); int(n) != len(want) && err != io.EOF {
t.Fatalf("PRead: got (%v, %v), wanted (%v, EOF)", n, err, len(want))
}
if want == string(buf) {
t.Fatalf("PRead: got %v, wanted %v", string(buf), want)
}
// Test failure if offset != 0.
if n, err := fd.Seek(ctx, 1, linux.SEEK_SET); n != 0 && err != nil {
t.Errorf("Seek: got err (%v, %v), wanted (0, nil)", n, err)
}
if n, err := fd.Write(ctx, writeIOSeq, WriteOptions{}); n != 0 && err != syserror.EINVAL {
t.Errorf("Write: got err (%v, %v), wanted (0, EINVAL)", n, err)
}
if n, err := fd.PWrite(ctx, writeIOSeq, 2, WriteOptions{}); n != 0 && err != syserror.EINVAL {
t.Errorf("PWrite: got err (%v, %v), wanted (0, EINVAL)", n, err)
}
}
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