gzip: new backend for wrapping Content-Encoding: gzip backends FIXME WIP

See: #2658

backend/all/all.go

@@ -18,6 +18,7 @@ import (
 	_ "github.com/rclone/rclone/backend/ftp"
 	_ "github.com/rclone/rclone/backend/googlecloudstorage"
 	_ "github.com/rclone/rclone/backend/googlephotos"
+	_ "github.com/rclone/rclone/backend/gzip"
 	_ "github.com/rclone/rclone/backend/hdfs"
 	_ "github.com/rclone/rclone/backend/http"
 	_ "github.com/rclone/rclone/backend/hubic"

backend/gzip/gzip.go

@@ -0,0 +1,578 @@
+// Package gzip provides wrappers for Fs and Object which implement compression
+package gzip
+
+import (
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/cache"
+	"github.com/rclone/rclone/fs/config/configmap"
+	"github.com/rclone/rclone/fs/config/configstruct"
+	"github.com/rclone/rclone/fs/hash"
+	"github.com/rclone/rclone/lib/readers"
+)
+
+// Globals
+// Register with Fs
+func init() {
+	fs.Register(&fs.RegInfo{
+		Name:        "gzip",
+		Description: "Compress/Decompress a remote",
+		NewFs:       NewFs,
+		Options: []fs.Option{{
+			Name:     "remote",
+			Help:     "Remote to compress/decompress.\nNormally should contain a ':' and a path, eg \"myremote:path/to/dir\",\n\"myremote:bucket\" or maybe \"myremote:\" (not recommended).",
+			Required: true,
+		}},
+	})
+}
+
+// NewFs constructs an Fs from the path, container:path
+func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, error) {
+	// Parse config into Options struct
+	opt := new(Options)
+	err := configstruct.Set(m, opt)
+	if err != nil {
+		return nil, err
+	}
+	// remote := opt.Remote
+	// if strings.HasPrefix(remote, name+":") {
+	// 	return nil, errors.New("can't point gzip remote at itself - check the value of the remote setting")
+	// }
+	// wInfo, wName, wPath, wConfig, err := fs.ConfigFs(remote)
+	// if err != nil {
+	// 	return nil, errors.Wrapf(err, "failed to parse remote %q to wrap", remote)
+	// }
+	// Make sure to remove trailing . referring to the current dir
+	// if path.Base(rpath) == "." {
+	// 	rpath = strings.TrimSuffix(rpath, ".")
+	// }
+	// Look for a file first
+	// remotePath := fspath.JoinRootPath(wPath, rpath)
+	// wrappedFs, err := wInfo.NewFs(wName, remotePath, wConfig)
+	// if that didn't produce a file, look for a directory
+	// if err != fs.ErrorIsFile {
+	// 	remotePath = fspath.JoinRootPath(wPath, rpath)
+	// 	wrappedFs, err = wInfo.NewFs(wName, remotePath, wConfig)
+	// }
+	// if err != fs.ErrorIsFile && err != nil {
+	// 	return nil, errors.Wrapf(err, "failed to make remote %s:%q to wrap", wName, remotePath)
+	// }
+
+	// Create the remote from the cache
+	wrappedFs, err := cache.Get(ctx, root)
+	if err != fs.ErrorIsFile && err != nil {
+		return nil, errors.Wrapf(err, "failed to make %q to wrap", root)
+	}
+	f := &Fs{
+		Fs:   wrappedFs,
+		name: name,
+		root: root,
+		opt:  *opt,
+	}
+	// the features here are ones we could support, and they are
+	// ANDed with the ones from wrappedFs
+	f.features = (&fs.Features{
+		CaseInsensitive:         true,
+		DuplicateFiles:          true,
+		ReadMimeType:            false, // MimeTypes not supported with gzip
+		WriteMimeType:           false,
+		BucketBased:             true,
+		CanHaveEmptyDirectories: true,
+		SetTier:                 true,
+		GetTier:                 true,
+	}).Fill(ctx, f).Mask(ctx, wrappedFs).WrapsFs(f, wrappedFs)
+
+	return f, err
+}
+
+// Options defines the configuration for this backend
+type Options struct {
+	Remote string `config:"remote"`
+}
+
+// Fs represents a wrapped fs.Fs
+type Fs struct {
+	fs.Fs
+	wrapper  fs.Fs
+	name     string
+	root     string
+	opt      Options
+	features *fs.Features // optional features
+}
+
+// Name of the remote (as passed into NewFs)
+func (f *Fs) Name() string {
+	return f.name
+}
+
+// Root of the remote (as passed into NewFs)
+func (f *Fs) Root() string {
+	return f.root
+}
+
+// Features returns the optional features of this Fs
+func (f *Fs) Features() *fs.Features {
+	return f.features
+}
+
+// String returns a description of the FS
+func (f *Fs) String() string {
+	return fmt.Sprintf("Compressed drive '%s:%s'", f.name, f.root)
+}
+
+// decompress some directory entries.  This alters entries returning
+// it as newEntries.
+func (f *Fs) decompressEntries(ctx context.Context, entries fs.DirEntries) (newEntries fs.DirEntries, err error) {
+	newEntries = entries[:0] // in place filter
+	for _, entry := range entries {
+		switch x := entry.(type) {
+		case fs.Object:
+			// FIXME decide if decompressing here or not
+			if strings.HasSuffix(x.Remote(), ".gz") {
+				newEntries = append(newEntries, f.newObject(x))
+			} else {
+				newEntries = append(newEntries, entry)
+			}
+		case fs.Directory:
+			newEntries = append(newEntries, entry)
+		default:
+			return nil, errors.Errorf("Unknown object type %T", entry)
+		}
+	}
+	return newEntries, nil
+}
+
+// List the objects and directories in dir into entries.  The
+// entries can be returned in any order but should be for a
+// complete directory.
+//
+// dir should be "" to list the root, and should not have
+// trailing slashes.
+//
+// This should return ErrDirNotFound if the directory isn't
+// found.
+func (f *Fs) List(ctx context.Context, dir string) (entries fs.DirEntries, err error) {
+	entries, err = f.Fs.List(ctx, dir)
+	if err != nil {
+		return nil, err
+	}
+	return f.decompressEntries(ctx, entries)
+}
+
+// ListR lists the objects and directories of the Fs starting
+// from dir recursively into out.
+//
+// dir should be "" to start from the root, and should not
+// have trailing slashes.
+//
+// This should return ErrDirNotFound if the directory isn't
+// found.
+//
+// It should call callback for each tranche of entries read.
+// These need not be returned in any particular order.  If
+// callback returns an error then the listing will stop
+// immediately.
+//
+// Don't implement this unless you have a more efficient way
+// of listing recursively that doing a directory traversal.
+func (f *Fs) ListR(ctx context.Context, dir string, callback fs.ListRCallback) (err error) {
+	return f.Fs.Features().ListR(ctx, dir, func(entries fs.DirEntries) error {
+		newEntries, err := f.decompressEntries(ctx, entries)
+		if err != nil {
+			return err
+		}
+		return callback(newEntries)
+	})
+}
+
+// returns the underlying name of in
+func (f *Fs) compressFileName(in string) string {
+	return in + ".gz"
+}
+
+// returns the compressed name of in
+func (f *Fs) decompressFileName(in string) string {
+	if strings.HasSuffix(in, ".gz") {
+		in = in[:len(in)-3]
+	}
+	return in
+}
+
+// A small wrapper to make sure we close the gzipper and the
+// underlying handle
+type decompress struct {
+	io.ReadCloser
+	underlying io.Closer
+}
+
+// Close the decompress object
+func (d *decompress) Close() error {
+	err := d.ReadCloser.Close()
+	err2 := d.underlying.Close()
+	if err == nil {
+		err = err2
+	}
+	return err
+}
+
+// Wrap in in a decompress object
+func (f *Fs) decompressData(in io.ReadCloser) (io.ReadCloser, error) {
+	rc, err := gzip.NewReader(in)
+	if err != nil {
+		return nil, err
+	}
+	return &decompress{ReadCloser: rc, underlying: in}, nil
+}
+
+type compress struct {
+	gzipWriter *gzip.Writer
+	pipeReader *io.PipeReader
+	pipeWriter *io.PipeWriter
+	errChan    chan error
+}
+
+func (c *compress) Read(p []byte) (n int, err error) {
+	// fs.Debugf(nil, "Read(%d)", len(p))
+	n, err = readers.ReadFill(c.pipeReader, p)
+	if err != nil && err != io.EOF {
+		_ = c.pipeWriter.CloseWithError(err)
+	}
+	// fs.Debugf(nil, "= %d, %v", n, err)
+	return n, err
+}
+
+func (c *compress) Close() (err error) {
+	// fs.Debugf(nil, "Close()")
+	_ = c.pipeReader.Close()
+	err = <-c.errChan
+	// fs.Debugf(nil, "= %v", err)
+	return err
+}
+
+func (f *Fs) compressData(in io.Reader) (rc io.ReadCloser, err error) {
+	c := &compress{
+		errChan: make(chan error, 1),
+	}
+	c.pipeReader, c.pipeWriter = io.Pipe()
+	c.gzipWriter, err = gzip.NewWriterLevel(c.pipeWriter, 9) // FIXME
+	if err != nil {
+		return nil, err
+	}
+	go func() {
+		_, err := io.Copy(c.gzipWriter, in)
+		err2 := c.gzipWriter.Close()
+		if err == nil {
+			err = err2
+		}
+		_ = c.pipeWriter.CloseWithError(err)
+		c.errChan <- err
+	}()
+	return c, nil
+}
+
+// NewObject finds the Object at remote.
+func (f *Fs) NewObject(ctx context.Context, remote string) (fs.Object, error) {
+	o, err := f.Fs.NewObject(ctx, f.compressFileName(remote))
+	if err != nil {
+		return nil, err
+	}
+	return f.newObject(o), nil
+}
+
+type putFn func(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error)
+
+// put implements Put or PutStream
+func (f *Fs) put(ctx context.Context, in io.Reader, src fs.ObjectInfo, options []fs.OpenOption, put putFn) (fs.Object, error) {
+	// Compress the data into compressor
+	compressor, err := f.compressData(in)
+	if err != nil {
+		return nil, err
+	}
+
+	// Transfer the data
+	o, err := put(ctx, compressor, f.newObjectInfo(src), options...)
+	if err != nil {
+		return nil, err
+	}
+
+	err = compressor.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	return f.newObject(o), nil
+}
+
+// Put in to the remote path with the modTime given of the given size
+//
+// May create the object even if it returns an error - if so
+// will return the object and the error, otherwise will return
+// nil and the error
+func (f *Fs) Put(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
+	return f.put(ctx, in, src, options, f.Fs.Put)
+}
+
+// PutStream uploads to the remote path with the modTime given of indeterminate size
+func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
+	return f.put(ctx, in, src, options, f.Fs.Features().PutStream)
+}
+
+// Hashes returns the supported hash sets.
+func (f *Fs) Hashes() hash.Set {
+	return hash.Set(hash.None)
+}
+
+// Copy src to this remote using server side copy operations.
+//
+// This is stored with the remote path given
+//
+// It returns the destination Object and a possible error
+//
+// Will only be called if src.Fs().Name() == f.Name()
+//
+// If it isn't possible then return fs.ErrorCantCopy
+func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
+	do := f.Fs.Features().Copy
+	if do == nil {
+		return nil, fs.ErrorCantCopy
+	}
+	o, ok := src.(*Object)
+	if !ok {
+		return nil, fs.ErrorCantCopy
+	}
+	oResult, err := do(ctx, o.Object, f.compressFileName(remote))
+	if err != nil {
+		return nil, err
+	}
+	return f.newObject(oResult), nil
+}
+
+// Move src to this remote using server side move operations.
+//
+// This is stored with the remote path given
+//
+// It returns the destination Object and a possible error
+//
+// Will only be called if src.Fs().Name() == f.Name()
+//
+// If it isn't possible then return fs.ErrorCantMove
+func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
+	do := f.Fs.Features().Move
+	if do == nil {
+		return nil, fs.ErrorCantMove
+	}
+	o, ok := src.(*Object)
+	if !ok {
+		return nil, fs.ErrorCantMove
+	}
+	oResult, err := do(ctx, o.Object, f.compressFileName(remote))
+	if err != nil {
+		return nil, err
+	}
+	return f.newObject(oResult), nil
+}
+
+// PutUnchecked uploads the object
+//
+// This will create a duplicate if we upload a new file without
+// checking to see if there is one already - use Put() for that.
+func (f *Fs) PutUnchecked(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
+	do := f.Fs.Features().PutUnchecked
+	if do == nil {
+		return nil, errors.New("can't PutUnchecked")
+	}
+	wrappedIn, err := f.compressData(in)
+	if err != nil {
+		return nil, err
+	}
+	o, err := do(ctx, wrappedIn, f.newObjectInfo(src))
+	if err != nil {
+		return nil, err
+	}
+	return f.newObject(o), nil
+}
+
+// UnWrap returns the Fs that this Fs is wrapping
+func (f *Fs) UnWrap() fs.Fs {
+	return f.Fs
+}
+
+// WrapFs returns the Fs that is wrapping this Fs
+func (f *Fs) WrapFs() fs.Fs {
+	return f.wrapper
+}
+
+// SetWrapper sets the Fs that is wrapping this Fs
+func (f *Fs) SetWrapper(wrapper fs.Fs) {
+	f.wrapper = wrapper
+}
+
+// Object describes a wrapped for being read from the Fs
+//
+// This decompresss the remote name and decompresss the data
+type Object struct {
+	fs.Object
+	f *Fs
+}
+
+func (f *Fs) newObject(o fs.Object) *Object {
+	return &Object{
+		Object: o,
+		f:      f,
+	}
+}
+
+// Fs returns read only access to the Fs that this object is part of
+func (o *Object) Fs() fs.Info {
+	return o.f
+}
+
+// Return a string version
+func (o *Object) String() string {
+	if o == nil {
+		return "<nil>"
+	}
+	return o.Remote()
+}
+
+// Remote returns the remote path
+func (o *Object) Remote() string {
+	remote := o.Object.Remote()
+	return o.f.decompressFileName(remote)
+}
+
+// Size returns the size of the file
+func (o *Object) Size() int64 {
+	return -1
+}
+
+// Hash returns the selected checksum of the file
+// If no checksum is available it returns ""
+func (o *Object) Hash(ctx context.Context, ht hash.Type) (string, error) {
+	return "", hash.ErrUnsupported
+}
+
+// UnWrap returns the wrapped Object
+func (o *Object) UnWrap() fs.Object {
+	return o.Object
+}
+
+// Open opens the file for read.  Call Close() on the returned io.ReadCloser
+func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (rc io.ReadCloser, err error) {
+	var openOptions []fs.OpenOption
+	var offset, limit int64 = 0, -1
+	for _, option := range options {
+		switch x := option.(type) {
+		case *fs.SeekOption:
+			offset = x.Offset
+		case *fs.RangeOption:
+			// FIXME o.Size() is wrong!
+			offset, limit = x.Decode(o.Size())
+		default:
+			// pass on Options to underlying open if appropriate
+			openOptions = append(openOptions, option)
+		}
+	}
+	rc, err = o.Object.Open(ctx, openOptions...)
+	if err != nil {
+		return nil, err
+	}
+	rc, err = o.f.decompressData(rc)
+	if err != nil {
+		return nil, err
+	}
+	// if offset set then discard some data
+	if offset > 0 {
+		_, err := io.CopyN(ioutil.Discard, rc, offset)
+		if err != nil {
+			return nil, err
+		}
+	}
+	// if limit set then apply limiter
+	if limit >= 0 {
+		rc = readers.NewLimitedReadCloser(rc, limit)
+	}
+	return rc, nil
+}
+
+// Update in to the object with the modTime given of the given size
+func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) error {
+	update := func(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error) {
+		return o.Object, o.Object.Update(ctx, in, src, options...)
+	}
+	_, err := o.f.put(ctx, in, src, options, update)
+	return err
+}
+
+// ObjectInfo describes a wrapped fs.ObjectInfo for being the source
+//
+// This compresss the remote name and adjusts the size
+type ObjectInfo struct {
+	fs.ObjectInfo
+	f *Fs
+}
+
+func (f *Fs) newObjectInfo(src fs.ObjectInfo) *ObjectInfo {
+	return &ObjectInfo{
+		ObjectInfo: src,
+		f:          f,
+	}
+}
+
+// Fs returns read only access to the Fs that this object is part of
+func (o *ObjectInfo) Fs() fs.Info {
+	return o.f
+}
+
+// Remote returns the remote path
+func (o *ObjectInfo) Remote() string {
+	return o.f.compressFileName(o.ObjectInfo.Remote())
+}
+
+// Size returns the size of the file
+func (o *ObjectInfo) Size() int64 {
+	return -1
+}
+
+// Hash returns the selected checksum of the file
+// If no checksum is available it returns ""
+func (o *ObjectInfo) Hash(ctx context.Context, hash hash.Type) (string, error) {
+	return "", nil
+}
+
+// Check the interfaces are satisfied
+var (
+	_ fs.Fs = (*Fs)(nil)
+	//	_ fs.Purger          = (*Fs)(nil)
+	_ fs.Copier = (*Fs)(nil)
+	_ fs.Mover  = (*Fs)(nil)
+	//	_ fs.DirMover        = (*Fs)(nil)
+	//	_ fs.Commander       = (*Fs)(nil)
+	_ fs.PutUncheckeder = (*Fs)(nil)
+	_ fs.PutStreamer    = (*Fs)(nil)
+	//	_ fs.CleanUpper      = (*Fs)(nil)
+	_ fs.UnWrapper = (*Fs)(nil)
+	_ fs.ListRer   = (*Fs)(nil)
+	//	_ fs.Abouter         = (*Fs)(nil)
+	_ fs.Wrapper = (*Fs)(nil)
+	//	_ fs.MergeDirser     = (*Fs)(nil)
+	//	_ fs.DirCacheFlusher = (*Fs)(nil)
+	//	_ fs.ChangeNotifier  = (*Fs)(nil)
+	//	_ fs.PublicLinker    = (*Fs)(nil)
+	//	_ fs.UserInfoer      = (*Fs)(nil)
+	//	_ fs.Disconnecter    = (*Fs)(nil)
+	_ fs.ObjectInfo      = (*ObjectInfo)(nil)
+	_ fs.Object          = (*Object)(nil)
+	_ fs.ObjectUnWrapper = (*Object)(nil)
+
+//	_ fs.IDer            = (*Object)(nil)
+//	_ fs.SetTierer       = (*Object)(nil)
+//	_ fs.GetTierer       = (*Object)(nil)
+)