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
|
// 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 linux
import (
"io"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/metric"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/sync"
)
var (
partialResultOnce sync.Once
)
// incrementPartialResultMetric increments PartialResultMetric by calling
// Increment(). This is added as the func Do() which is called below requires
// us to pass a function which does not take any arguments, whereas Increment()
// takes a variadic number of arguments.
func incrementPartialResultMetric() {
metric.WeirdnessMetric.Increment(&metric.WeirdnessTypePartialResult)
}
// HandleIOError handles special error cases for partial results. For some
// errors, we may consume the error and return only the partial read/write.
//
// op and f are used only for panics.
func HandleIOError(ctx context.Context, partialResult bool, ioerr, intr error, op string, f *vfs.FileDescription) error {
known, err := handleIOErrorImpl(ctx, partialResult, ioerr, intr, op)
if err != nil {
return err
}
if !known {
// An unknown error is encountered with a partial read/write.
fs := f.Mount().Filesystem().VirtualFilesystem()
root := vfs.RootFromContext(ctx)
name, _ := fs.PathnameWithDeleted(ctx, root, f.VirtualDentry())
log.Traceback("Invalid request partialResult %v and err (type %T) %v for %s operation on %q", partialResult, ioerr, ioerr, op, name)
partialResultOnce.Do(incrementPartialResultMetric)
}
return nil
}
// handleIOError handles special error cases for partial results. For some
// errors, we may consume the error and return only the partial read/write.
//
// Returns false if error is unknown.
func handleIOErrorImpl(ctx context.Context, partialResult bool, errOrig, intr error, op string) (bool, error) {
if errOrig == nil {
// Typical successful syscall.
return true, nil
}
// Translate error, if possible, to consolidate errors from other packages
// into a smaller set of errors from linuxerr package.
translatedErr := errOrig
if errno, ok := linuxerr.TranslateError(errOrig); ok {
translatedErr = errno
}
switch {
case translatedErr == io.EOF:
// EOF is always consumed. If this is a partial read/write
// (result != 0), the application will see that, otherwise
// they will see 0.
return true, nil
case linuxerr.Equals(linuxerr.EFBIG, translatedErr):
t := kernel.TaskFromContext(ctx)
if t == nil {
panic("I/O error should only occur from a context associated with a Task")
}
// Ignore partialResult because this error only applies to
// normal files, and for those files we cannot accumulate
// write results.
//
// Do not consume the error and return it as EFBIG.
// Simultaneously send a SIGXFSZ per setrlimit(2).
t.SendSignal(kernel.SignalInfoNoInfo(linux.SIGXFSZ, t, t))
return true, linuxerr.EFBIG
case linuxerr.Equals(linuxerr.EINTR, translatedErr):
// The syscall was interrupted. Return nil if it completed
// partially, otherwise return the error code that the syscall
// needs (to indicate to the kernel what it should do).
if partialResult {
return true, nil
}
return true, intr
}
if !partialResult {
// Typical syscall error.
return true, errOrig
}
switch {
case linuxerr.Equals(linuxerr.EINTR, translatedErr):
// Syscall interrupted, but completed a partial
// read/write. Like ErrWouldBlock, since we have a
// partial read/write, we consume the error and return
// the partial result.
return true, nil
case linuxerr.Equals(linuxerr.EFAULT, translatedErr):
// EFAULT is only shown the user if nothing was
// read/written. If we read something (this case), they see
// a partial read/write. They will then presumably try again
// with an incremented buffer, which will EFAULT with
// result == 0.
return true, nil
case linuxerr.Equals(linuxerr.EPIPE, translatedErr):
// Writes to a pipe or socket will return EPIPE if the other
// side is gone. The partial write is returned. EPIPE will be
// returned on the next call.
//
// TODO(gvisor.dev/issue/161): In some cases SIGPIPE should
// also be sent to the application.
return true, nil
case linuxerr.Equals(linuxerr.ENOSPC, translatedErr):
// Similar to EPIPE. Return what we wrote this time, and let
// ENOSPC be returned on the next call.
return true, nil
case linuxerr.Equals(linuxerr.ECONNRESET, translatedErr):
fallthrough
case linuxerr.Equals(linuxerr.ECONNABORTED, translatedErr):
fallthrough
case linuxerr.Equals(linuxerr.ETIMEDOUT, translatedErr):
// For TCP sendfile connections, we may have a reset, abort or timeout. But
// we should just return the partial result. The next call will return the
// error without a partial IO operation.
return true, nil
case linuxerr.Equals(linuxerr.EWOULDBLOCK, translatedErr):
// Syscall would block, but completed a partial read/write.
// This case should only be returned by IssueIO for nonblocking
// files. Since we have a partial read/write, we consume
// ErrWouldBlock, returning the partial result.
return true, nil
case linuxerr.IsRestartError(translatedErr):
// Identical to the EINTR case.
return true, nil
}
// Error is unknown and cannot be properly handled.
return false, nil
}
|
