1package vfs // import "github.com/docker/docker/daemon/graphdriver/vfs"
2
3import (
4	"fmt"
5	"os"
6	"path/filepath"
7
8	"github.com/docker/docker/daemon/graphdriver"
9	"github.com/docker/docker/daemon/graphdriver/quota"
10	"github.com/docker/docker/errdefs"
11	"github.com/docker/docker/pkg/containerfs"
12	"github.com/docker/docker/pkg/idtools"
13	"github.com/docker/docker/pkg/parsers"
14	"github.com/docker/docker/pkg/system"
15	"github.com/docker/go-units"
16	"github.com/opencontainers/selinux/go-selinux/label"
17	"github.com/pkg/errors"
18)
19
20var (
21	// CopyDir defines the copy method to use.
22	CopyDir = dirCopy
23)
24
25func init() {
26	graphdriver.Register("vfs", Init)
27}
28
29// Init returns a new VFS driver.
30// This sets the home directory for the driver and returns NaiveDiffDriver.
31func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
32	d := &Driver{
33		home:      home,
34		idMapping: idtools.NewIDMappingsFromMaps(uidMaps, gidMaps),
35	}
36
37	if err := d.parseOptions(options); err != nil {
38		return nil, err
39	}
40
41	rootIDs := d.idMapping.RootPair()
42	if err := idtools.MkdirAllAndChown(home, 0700, rootIDs); err != nil {
43		return nil, err
44	}
45
46	setupDriverQuota(d)
47
48	if size := d.getQuotaOpt(); !d.quotaSupported() && size > 0 {
49		return nil, quota.ErrQuotaNotSupported
50	}
51
52	return graphdriver.NewNaiveDiffDriver(d, uidMaps, gidMaps), nil
53}
54
55// Driver holds information about the driver, home directory of the driver.
56// Driver implements graphdriver.ProtoDriver. It uses only basic vfs operations.
57// In order to support layering, files are copied from the parent layer into the new layer. There is no copy-on-write support.
58// Driver must be wrapped in NaiveDiffDriver to be used as a graphdriver.Driver
59type Driver struct {
60	driverQuota
61	home      string
62	idMapping *idtools.IdentityMapping
63}
64
65func (d *Driver) String() string {
66	return "vfs"
67}
68
69// Status is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any status information.
70func (d *Driver) Status() [][2]string {
71	return nil
72}
73
74// GetMetadata is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any meta data.
75func (d *Driver) GetMetadata(id string) (map[string]string, error) {
76	return nil, nil
77}
78
79// Cleanup is used to implement graphdriver.ProtoDriver. There is no cleanup required for this driver.
80func (d *Driver) Cleanup() error {
81	return nil
82}
83
84func (d *Driver) parseOptions(options []string) error {
85	for _, option := range options {
86		key, val, err := parsers.ParseKeyValueOpt(option)
87		if err != nil {
88			return errdefs.InvalidParameter(err)
89		}
90		switch key {
91		case "size":
92			size, err := units.RAMInBytes(val)
93			if err != nil {
94				return errdefs.InvalidParameter(err)
95			}
96			if err = d.setQuotaOpt(uint64(size)); err != nil {
97				return errdefs.InvalidParameter(errors.Wrap(err, "failed to set option size for vfs"))
98			}
99		default:
100			return errdefs.InvalidParameter(errors.Errorf("unknown option %s for vfs", key))
101		}
102	}
103	return nil
104}
105
106// CreateReadWrite creates a layer that is writable for use as a container
107// file system.
108func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
109	quotaSize := d.getQuotaOpt()
110
111	if opts != nil {
112		for key, val := range opts.StorageOpt {
113			switch key {
114			case "size":
115				if !d.quotaSupported() {
116					return quota.ErrQuotaNotSupported
117				}
118				size, err := units.RAMInBytes(val)
119				if err != nil {
120					return errdefs.InvalidParameter(err)
121				}
122				quotaSize = uint64(size)
123			default:
124				return errdefs.InvalidParameter(errors.Errorf("Storage opt %s not supported", key))
125			}
126		}
127	}
128
129	return d.create(id, parent, quotaSize)
130}
131
132// Create prepares the filesystem for the VFS driver and copies the directory for the given id under the parent.
133func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
134	if opts != nil && len(opts.StorageOpt) != 0 {
135		return fmt.Errorf("--storage-opt is not supported for vfs on read-only layers")
136	}
137
138	return d.create(id, parent, 0)
139}
140
141func (d *Driver) create(id, parent string, size uint64) error {
142	dir := d.dir(id)
143	rootIDs := d.idMapping.RootPair()
144	if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0700, rootIDs); err != nil {
145		return err
146	}
147	if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil {
148		return err
149	}
150
151	if size != 0 {
152		if err := d.setupQuota(dir, size); err != nil {
153			return err
154		}
155	}
156
157	labelOpts := []string{"level:s0"}
158	if _, mountLabel, err := label.InitLabels(labelOpts); err == nil {
159		label.SetFileLabel(dir, mountLabel)
160	}
161	if parent == "" {
162		return nil
163	}
164	parentDir, err := d.Get(parent, "")
165	if err != nil {
166		return fmt.Errorf("%s: %s", parent, err)
167	}
168	return CopyDir(parentDir.Path(), dir)
169}
170
171func (d *Driver) dir(id string) string {
172	return filepath.Join(d.home, "dir", filepath.Base(id))
173}
174
175// Remove deletes the content from the directory for a given id.
176func (d *Driver) Remove(id string) error {
177	return system.EnsureRemoveAll(d.dir(id))
178}
179
180// Get returns the directory for the given id.
181func (d *Driver) Get(id, mountLabel string) (containerfs.ContainerFS, error) {
182	dir := d.dir(id)
183	if st, err := os.Stat(dir); err != nil {
184		return nil, err
185	} else if !st.IsDir() {
186		return nil, fmt.Errorf("%s: not a directory", dir)
187	}
188	return containerfs.NewLocalContainerFS(dir), nil
189}
190
191// Put is a noop for vfs that return nil for the error, since this driver has no runtime resources to clean up.
192func (d *Driver) Put(id string) error {
193	// The vfs driver has no runtime resources (e.g. mounts)
194	// to clean up, so we don't need anything here
195	return nil
196}
197
198// Exists checks to see if the directory exists for the given id.
199func (d *Driver) Exists(id string) bool {
200	_, err := os.Stat(d.dir(id))
201	return err == nil
202}
203