1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
// 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 := &VirtualFilesystem{}
if err := vfsObj.Init(); err != nil {
t.Fatalf("VFS init: %v", err)
}
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 := &VirtualFilesystem{}
if err := vfsObj.Init(); err != nil {
t.Fatalf("VFS init: %v", err)
}
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)
}
}
|
