142 lines
4.5 KiB
Go
142 lines
4.5 KiB
Go
// 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/sentry/context"
|
|
"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
|
|
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
|
|
"gvisor.dev/gvisor/pkg/sentry/usermem"
|
|
"gvisor.dev/gvisor/pkg/syserror"
|
|
)
|
|
|
|
// 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
|
|
}
|
|
|
|
// genCountFD is a read-only FileDescriptionImpl representing a regular file
|
|
// that contains the number of times its DynamicBytesSource.Generate()
|
|
// implementation has been called.
|
|
type genCountFD struct {
|
|
fileDescription
|
|
DynamicBytesFileDescriptionImpl
|
|
|
|
count uint64 // accessed using atomic memory ops
|
|
}
|
|
|
|
func newGenCountFD(mnt *Mount, vfsd *Dentry) *FileDescription {
|
|
var fd genCountFD
|
|
fd.vfsfd.Init(&fd, mnt, vfsd)
|
|
fd.DynamicBytesFileDescriptionImpl.SetDataSource(&fd)
|
|
return &fd.vfsfd
|
|
}
|
|
|
|
// Release implements FileDescriptionImpl.Release.
|
|
func (fd *genCountFD) Release() {
|
|
}
|
|
|
|
// StatusFlags implements FileDescriptionImpl.StatusFlags.
|
|
func (fd *genCountFD) StatusFlags(ctx context.Context) (uint32, error) {
|
|
return 0, nil
|
|
}
|
|
|
|
// SetStatusFlags implements FileDescriptionImpl.SetStatusFlags.
|
|
func (fd *genCountFD) SetStatusFlags(ctx context.Context, flags uint32) error {
|
|
return syserror.EPERM
|
|
}
|
|
|
|
// Stat implements FileDescriptionImpl.Stat.
|
|
func (fd *genCountFD) 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 *genCountFD) SetStat(ctx context.Context, opts SetStatOptions) error {
|
|
return syserror.EPERM
|
|
}
|
|
|
|
// Generate implements DynamicBytesSource.Generate.
|
|
func (fd *genCountFD) Generate(ctx context.Context, buf *bytes.Buffer) error {
|
|
fmt.Fprintf(buf, "%d", atomic.AddUint64(&fd.count, 1))
|
|
return nil
|
|
}
|
|
|
|
func TestGenCountFD(t *testing.T) {
|
|
ctx := contexttest.Context(t)
|
|
creds := auth.CredentialsFromContext(ctx)
|
|
|
|
vfsObj := New() // vfs.New()
|
|
vfsObj.MustRegisterFilesystemType("testfs", FDTestFilesystemType{})
|
|
mntns, err := vfsObj.NewMountNamespace(ctx, creds, "", "testfs", &NewFilesystemOptions{})
|
|
if err != nil {
|
|
t.Fatalf("failed to create testfs root mount: %v", err)
|
|
}
|
|
vd := mntns.Root()
|
|
defer vd.DecRef()
|
|
|
|
fd := newGenCountFD(vd.Mount(), vd.Dentry())
|
|
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.Impl().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.Impl().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.Impl().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.Impl().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.Impl().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)
|
|
}
|
|
}
|