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/errdefs"
10	"github.com/docker/docker/pkg/containerfs"
11	"github.com/docker/docker/pkg/idtools"
12	"github.com/docker/docker/pkg/parsers"
13	"github.com/docker/docker/pkg/system"
14	"github.com/docker/docker/quota"
15	units "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	if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil {
42		return nil, err
43	}
44
45	setupDriverQuota(d)
46
47	if size := d.getQuotaOpt(); !d.quotaSupported() && size > 0 {
48		return nil, quota.ErrQuotaNotSupported
49	}
50
51	return graphdriver.NewNaiveDiffDriver(d, uidMaps, gidMaps), nil
52}
53
54// Driver holds information about the driver, home directory of the driver.
55// Driver implements graphdriver.ProtoDriver. It uses only basic vfs operations.
56// In order to support layering, files are copied from the parent layer into the new layer. There is no copy-on-write support.
57// Driver must be wrapped in NaiveDiffDriver to be used as a graphdriver.Driver
58type Driver struct {
59	driverQuota
60	home      string
61	idMapping *idtools.IdentityMapping
62}
63
64func (d *Driver) String() string {
65	return "vfs"
66}
67
68// Status is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any status information.
69func (d *Driver) Status() [][2]string {
70	return nil
71}
72
73// GetMetadata is used for implementing the graphdriver.ProtoDriver interface. VFS does not currently have any meta data.
74func (d *Driver) GetMetadata(id string) (map[string]string, error) {
75	return nil, nil
76}
77
78// Cleanup is used to implement graphdriver.ProtoDriver. There is no cleanup required for this driver.
79func (d *Driver) Cleanup() error {
80	return nil
81}
82
83func (d *Driver) parseOptions(options []string) error {
84	for _, option := range options {
85		key, val, err := parsers.ParseKeyValueOpt(option)
86		if err != nil {
87			return errdefs.InvalidParameter(err)
88		}
89		switch key {
90		case "size":
91			size, err := units.RAMInBytes(val)
92			if err != nil {
93				return errdefs.InvalidParameter(err)
94			}
95			if err = d.setQuotaOpt(uint64(size)); err != nil {
96				return errdefs.InvalidParameter(errors.Wrap(err, "failed to set option size for vfs"))
97			}
98		default:
99			return errdefs.InvalidParameter(errors.Errorf("unknown option %s for vfs", key))
100		}
101	}
102	return nil
103}
104
105// CreateReadWrite creates a layer that is writable for use as a container
106// file system.
107func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
108	quotaSize := d.getQuotaOpt()
109
110	if opts != nil {
111		for key, val := range opts.StorageOpt {
112			switch key {
113			case "size":
114				if !d.quotaSupported() {
115					return quota.ErrQuotaNotSupported
116				}
117				size, err := units.RAMInBytes(val)
118				if err != nil {
119					return errdefs.InvalidParameter(err)
120				}
121				quotaSize = uint64(size)
122			default:
123				return errdefs.InvalidParameter(errors.Errorf("Storage opt %s not supported", key))
124			}
125		}
126	}
127
128	return d.create(id, parent, quotaSize)
129}
130
131// Create prepares the filesystem for the VFS driver and copies the directory for the given id under the parent.
132func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
133	if opts != nil && len(opts.StorageOpt) != 0 {
134		return fmt.Errorf("--storage-opt is not supported for vfs on read-only layers")
135	}
136
137	return d.create(id, parent, 0)
138}
139
140func (d *Driver) create(id, parent string, size uint64) error {
141	dir := d.dir(id)
142	rootIDs := d.idMapping.RootPair()
143	if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0701, idtools.CurrentIdentity()); err != nil {
144		return err
145	}
146	if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil {
147		return err
148	}
149
150	if size != 0 {
151		if err := d.setupQuota(dir, size); err != nil {
152			return err
153		}
154	}
155
156	labelOpts := []string{"level:s0"}
157	if _, mountLabel, err := label.InitLabels(labelOpts); err == nil {
158		label.SetFileLabel(dir, mountLabel)
159	}
160	if parent == "" {
161		return nil
162	}
163	parentDir, err := d.Get(parent, "")
164	if err != nil {
165		return fmt.Errorf("%s: %s", parent, err)
166	}
167	return CopyDir(parentDir.Path(), dir)
168}
169
170func (d *Driver) dir(id string) string {
171	return filepath.Join(d.home, "dir", filepath.Base(id))
172}
173
174// Remove deletes the content from the directory for a given id.
175func (d *Driver) Remove(id string) error {
176	return system.EnsureRemoveAll(d.dir(id))
177}
178
179// Get returns the directory for the given id.
180func (d *Driver) Get(id, mountLabel string) (containerfs.ContainerFS, error) {
181	dir := d.dir(id)
182	if st, err := os.Stat(dir); err != nil {
183		return nil, err
184	} else if !st.IsDir() {
185		return nil, fmt.Errorf("%s: not a directory", dir)
186	}
187	return containerfs.NewLocalContainerFS(dir), nil
188}
189
190// Put is a noop for vfs that return nil for the error, since this driver has no runtime resources to clean up.
191func (d *Driver) Put(id string) error {
192	// The vfs driver has no runtime resources (e.g. mounts)
193	// to clean up, so we don't need anything here
194	return nil
195}
196
197// Exists checks to see if the directory exists for the given id.
198func (d *Driver) Exists(id string) bool {
199	_, err := os.Stat(d.dir(id))
200	return err == nil
201}
202