distribution/registry/storage/driver/base/base.go

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// Package base provides a base implementation of the storage driver that can
// be used to implement common checks. The goal is to increase the amount of
// code sharing.
//
// The canonical approach to use this class is to embed in the exported driver
// struct such that calls are proxied through this implementation. First,
// declare the internal driver, as follows:
//
// type driver struct { ... internal ...}
//
// The resulting type should implement StorageDriver such that it can be the
// target of a Base struct. The exported type can then be declared as follows:
//
// type Driver struct {
// Base
// }
//
// Because Driver embeds Base, it effectively implements Base. If the driver
// needs to intercept a call, before going to base, Driver should implement
// that method. Effectively, Driver can intercept calls before coming in and
// driver implements the actual logic.
//
// To further shield the embed from other packages, it is recommended to
// employ a private embed struct:
//
// type baseEmbed struct {
// base.Base
// }
//
// Then, declare driver to embed baseEmbed, rather than Base directly:
//
// type Driver struct {
// baseEmbed
// }
//
// The type now implements StorageDriver, proxying through Base, without
// exporting an unnecessary field.
package base
import (
"context"
"io"
dcontext "github.com/docker/distribution/context"
storagedriver "github.com/docker/distribution/registry/storage/driver"
)
// Base provides a wrapper around a storagedriver implementation that provides
// common path and bounds checking.
type Base struct {
storagedriver.StorageDriver
}
// Format errors received from the storage driver
func (base *Base) setDriverName(e error) error {
switch actual := e.(type) {
case nil:
return nil
case storagedriver.ErrUnsupportedMethod:
actual.DriverName = base.StorageDriver.Name()
return actual
case storagedriver.PathNotFoundError:
actual.DriverName = base.StorageDriver.Name()
return actual
case storagedriver.InvalidPathError:
actual.DriverName = base.StorageDriver.Name()
return actual
case storagedriver.InvalidOffsetError:
actual.DriverName = base.StorageDriver.Name()
return actual
default:
storageError := storagedriver.Error{
DriverName: base.StorageDriver.Name(),
Enclosed: e,
}
return storageError
}
}
// GetContent wraps GetContent of underlying storage driver.
func (base *Base) GetContent(ctx context.Context, path string) ([]byte, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.GetContent(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) {
return nil, storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
b, e := base.StorageDriver.GetContent(ctx, path)
return b, base.setDriverName(e)
}
// PutContent wraps PutContent of underlying storage driver.
func (base *Base) PutContent(ctx context.Context, path string, content []byte) error {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.PutContent(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) {
return storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
return base.setDriverName(base.StorageDriver.PutContent(ctx, path, content))
}
// Reader wraps Reader of underlying storage driver.
func (base *Base) Reader(ctx context.Context, path string, offset int64) (io.ReadCloser, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Reader(%q, %d)", base.Name(), path, offset)
if offset < 0 {
return nil, storagedriver.InvalidOffsetError{Path: path, Offset: offset, DriverName: base.StorageDriver.Name()}
}
if !storagedriver.PathRegexp.MatchString(path) {
return nil, storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
rc, e := base.StorageDriver.Reader(ctx, path, offset)
return rc, base.setDriverName(e)
}
// Writer wraps Writer of underlying storage driver.
func (base *Base) Writer(ctx context.Context, path string, append bool) (storagedriver.FileWriter, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Writer(%q, %v)", base.Name(), path, append)
if !storagedriver.PathRegexp.MatchString(path) {
return nil, storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
writer, e := base.StorageDriver.Writer(ctx, path, append)
return writer, base.setDriverName(e)
}
// Stat wraps Stat of underlying storage driver.
func (base *Base) Stat(ctx context.Context, path string) (storagedriver.FileInfo, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Stat(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) && path != "/" {
return nil, storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
fi, e := base.StorageDriver.Stat(ctx, path)
return fi, base.setDriverName(e)
}
// List wraps List of underlying storage driver.
func (base *Base) List(ctx context.Context, path string) ([]string, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.List(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) && path != "/" {
return nil, storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
str, e := base.StorageDriver.List(ctx, path)
return str, base.setDriverName(e)
}
// Move wraps Move of underlying storage driver.
func (base *Base) Move(ctx context.Context, sourcePath string, destPath string) error {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Move(%q, %q", base.Name(), sourcePath, destPath)
if !storagedriver.PathRegexp.MatchString(sourcePath) {
return storagedriver.InvalidPathError{Path: sourcePath, DriverName: base.StorageDriver.Name()}
} else if !storagedriver.PathRegexp.MatchString(destPath) {
return storagedriver.InvalidPathError{Path: destPath, DriverName: base.StorageDriver.Name()}
}
return base.setDriverName(base.StorageDriver.Move(ctx, sourcePath, destPath))
}
// Delete wraps Delete of underlying storage driver.
func (base *Base) Delete(ctx context.Context, path string) error {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Delete(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) {
return storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
return base.setDriverName(base.StorageDriver.Delete(ctx, path))
}
// URLFor wraps URLFor of underlying storage driver.
func (base *Base) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.URLFor(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) {
return "", storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
str, e := base.StorageDriver.URLFor(ctx, path, options)
return str, base.setDriverName(e)
}
// Walk wraps Walk of underlying storage driver.
func (base *Base) Walk(ctx context.Context, path string, f storagedriver.WalkFn) error {
ctx, done := dcontext.WithTrace(ctx)
defer done("%s.Walk(%q)", base.Name(), path)
if !storagedriver.PathRegexp.MatchString(path) {
return storagedriver.InvalidPathError{Path: path, DriverName: base.StorageDriver.Name()}
}
return base.setDriverName(base.StorageDriver.Walk(ctx, path, f))
}