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
|
// 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 (
"fmt"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/syserror"
)
// DeviceKind indicates whether a device is a block or character device.
//
// +stateify savable
type DeviceKind uint32
const (
// BlockDevice indicates a block device.
BlockDevice DeviceKind = iota
// CharDevice indicates a character device.
CharDevice
)
// String implements fmt.Stringer.String.
func (kind DeviceKind) String() string {
switch kind {
case BlockDevice:
return "block"
case CharDevice:
return "character"
default:
return fmt.Sprintf("invalid device kind %d", kind)
}
}
// +stateify savable
type devTuple struct {
kind DeviceKind
major uint32
minor uint32
}
// A Device backs device special files.
type Device interface {
// Open returns a FileDescription representing this device.
Open(ctx context.Context, mnt *Mount, d *Dentry, opts OpenOptions) (*FileDescription, error)
}
// +stateify savable
type registeredDevice struct {
dev Device
opts RegisterDeviceOptions
}
// RegisterDeviceOptions contains options to
// VirtualFilesystem.RegisterDevice().
//
// +stateify savable
type RegisterDeviceOptions struct {
// GroupName is the name shown for this device registration in
// /proc/devices. If GroupName is empty, this registration will not be
// shown in /proc/devices.
GroupName string
}
// RegisterDevice registers the given Device in vfs with the given major and
// minor device numbers.
func (vfs *VirtualFilesystem) RegisterDevice(kind DeviceKind, major, minor uint32, dev Device, opts *RegisterDeviceOptions) error {
tup := devTuple{kind, major, minor}
vfs.devicesMu.Lock()
defer vfs.devicesMu.Unlock()
if existing, ok := vfs.devices[tup]; ok {
return fmt.Errorf("%s device number (%d, %d) is already registered to device type %T", kind, major, minor, existing.dev)
}
vfs.devices[tup] = ®isteredDevice{
dev: dev,
opts: *opts,
}
return nil
}
// OpenDeviceSpecialFile returns a FileDescription representing the given
// device.
func (vfs *VirtualFilesystem) OpenDeviceSpecialFile(ctx context.Context, mnt *Mount, d *Dentry, kind DeviceKind, major, minor uint32, opts *OpenOptions) (*FileDescription, error) {
tup := devTuple{kind, major, minor}
vfs.devicesMu.RLock()
defer vfs.devicesMu.RUnlock()
rd, ok := vfs.devices[tup]
if !ok {
return nil, syserror.ENXIO
}
return rd.dev.Open(ctx, mnt, d, *opts)
}
// GetAnonBlockDevMinor allocates and returns an unused minor device number for
// an "anonymous" block device with major number UNNAMED_MAJOR.
func (vfs *VirtualFilesystem) GetAnonBlockDevMinor() (uint32, error) {
vfs.anonBlockDevMinorMu.Lock()
defer vfs.anonBlockDevMinorMu.Unlock()
minor := vfs.anonBlockDevMinorNext
const maxDevMinor = (1 << 20) - 1
for minor < maxDevMinor {
if _, ok := vfs.anonBlockDevMinor[minor]; !ok {
vfs.anonBlockDevMinor[minor] = struct{}{}
vfs.anonBlockDevMinorNext = minor + 1
return minor, nil
}
minor++
}
return 0, syserror.EMFILE
}
// PutAnonBlockDevMinor deallocates a minor device number returned by a
// previous call to GetAnonBlockDevMinor.
func (vfs *VirtualFilesystem) PutAnonBlockDevMinor(minor uint32) {
vfs.anonBlockDevMinorMu.Lock()
defer vfs.anonBlockDevMinorMu.Unlock()
delete(vfs.anonBlockDevMinor, minor)
if minor < vfs.anonBlockDevMinorNext {
vfs.anonBlockDevMinorNext = minor
}
}
|
