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
|
// Copyright 2018 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 fdpipe implements common namedpipe opening and accessing logic.
package fdpipe
import (
"os"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fd"
"gvisor.dev/gvisor/pkg/fdnotifier"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/safemem"
"gvisor.dev/gvisor/pkg/secio"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
// pipeOperations are the fs.FileOperations of a host pipe.
//
// +stateify savable
type pipeOperations struct {
fsutil.FilePipeSeek `state:"nosave"`
fsutil.FileNotDirReaddir `state:"nosave"`
fsutil.FileNoFsync `state:"nosave"`
fsutil.FileNoopFlush `state:"nosave"`
fsutil.FileNoMMap `state:"nosave"`
fsutil.FileNoIoctl `state:"nosave"`
fsutil.FileNoSplice `state:"nosave"`
fsutil.FileUseInodeUnstableAttr `state:"nosave"`
waiter.Queue `state:"nosave"`
// flags are the flags used to open the pipe.
flags fs.FileFlags `state:".(fs.FileFlags)"`
// opener is how the pipe was opened.
opener NonBlockingOpener `state:"wait"`
// file represents the host pipe.
file *fd.FD `state:"nosave"`
// mu protects readAheadBuffer access below.
mu sync.Mutex `state:"nosave"`
// readAheadBuffer contains read bytes that have not yet been read
// by the application but need to be buffered for save-restore for correct
// opening semantics. The readAheadBuffer will only be non-empty when the
// is first opened and will be drained by subsequent reads on the pipe.
readAheadBuffer []byte
}
// newPipeOperations returns an implementation of fs.FileOperations for a pipe.
func newPipeOperations(ctx context.Context, opener NonBlockingOpener, flags fs.FileFlags, file *fd.FD, readAheadBuffer []byte) (*pipeOperations, error) {
pipeOps := &pipeOperations{
flags: flags,
opener: opener,
file: file,
readAheadBuffer: readAheadBuffer,
}
if err := pipeOps.init(); err != nil {
return nil, err
}
return pipeOps, nil
}
// init initializes p.file.
func (p *pipeOperations) init() error {
var s unix.Stat_t
if err := unix.Fstat(p.file.FD(), &s); err != nil {
log.Warningf("pipe: cannot stat fd %d: %v", p.file.FD(), err)
return unix.EINVAL
}
if (s.Mode & unix.S_IFMT) != unix.S_IFIFO {
log.Warningf("pipe: cannot load fd %d as pipe, file type: %o", p.file.FD(), s.Mode)
return unix.EINVAL
}
if err := unix.SetNonblock(p.file.FD(), true); err != nil {
return err
}
return fdnotifier.AddFD(int32(p.file.FD()), &p.Queue)
}
// EventRegister implements waiter.Waitable.EventRegister.
func (p *pipeOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
p.Queue.EventRegister(e, mask)
fdnotifier.UpdateFD(int32(p.file.FD()))
}
// EventUnregister implements waiter.Waitable.EventUnregister.
func (p *pipeOperations) EventUnregister(e *waiter.Entry) {
p.Queue.EventUnregister(e)
fdnotifier.UpdateFD(int32(p.file.FD()))
}
// Readiness returns a mask of ready events for stream.
func (p *pipeOperations) Readiness(mask waiter.EventMask) (eventMask waiter.EventMask) {
return fdnotifier.NonBlockingPoll(int32(p.file.FD()), mask)
}
// Release implements fs.FileOperations.Release.
func (p *pipeOperations) Release(context.Context) {
fdnotifier.RemoveFD(int32(p.file.FD()))
p.file.Close()
p.file = nil
}
// Read implements fs.FileOperations.Read.
func (p *pipeOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
// Drain the read ahead buffer, if it contains anything first.
var bufN int
var bufErr error
p.mu.Lock()
if len(p.readAheadBuffer) > 0 {
bufN, bufErr = dst.CopyOut(ctx, p.readAheadBuffer)
p.readAheadBuffer = p.readAheadBuffer[bufN:]
dst = dst.DropFirst(bufN)
}
p.mu.Unlock()
if dst.NumBytes() == 0 || bufErr != nil {
return int64(bufN), bufErr
}
// Pipes expect full reads.
n, err := dst.CopyOutFrom(ctx, safemem.FromIOReader{secio.FullReader{p.file}})
total := int64(bufN) + n
if err != nil && isBlockError(err) {
return total, syserror.ErrWouldBlock
}
return total, err
}
// Write implements fs.FileOperations.Write.
func (p *pipeOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
n, err := src.CopyInTo(ctx, safemem.FromIOWriter{p.file})
if err != nil && isBlockError(err) {
return n, syserror.ErrWouldBlock
}
return n, err
}
// isBlockError unwraps os errors and checks if they are caused by EAGAIN or
// EWOULDBLOCK. This is so they can be transformed into syserror.ErrWouldBlock.
func isBlockError(err error) bool {
if linuxerr.Equals(linuxerr.EAGAIN, err) || linuxerr.Equals(linuxerr.EWOULDBLOCK, err) {
return true
}
if pe, ok := err.(*os.PathError); ok {
return isBlockError(pe.Err)
}
return false
}
|
