coreapi unixfs: unixfs.Get

License: MIT
Signed-off-by: Łukasz Magiera <magik6k@gmail.com>

core/coreapi/interface/unixfs.go

@@ -13,8 +13,16 @@ import (
 // NOTE: This API is heavily WIP, things are guaranteed to break frequently
 type UnixfsAPI interface {
 	// Add imports the data from the reader into merkledag file
+	//
+	// TODO: a long useful comment on how to use this for many different scenarios
 	Add(context.Context, files.File, ...options.UnixfsAddOption) (ResolvedPath, error)
 
+	// Get returns a read-only handle to a file tree referenced by a path
+	//
+	// Note that some implementations of this API may apply the specified context
+	// to operations performed on the returned file
+	Get(context.Context, Path) (files.File, error)
+
 	// Cat returns a reader for the file
 	Cat(context.Context, Path) (Reader, error)
 

core/coreapi/unixfile.go

@@ -0,0 +1,200 @@
+package coreapi
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	gopath "path"
+	"time"
+
+	files "gx/ipfs/QmSP88ryZkHSRn1fnngAaV2Vcn63WUJzAavnRM9CVdU1Ky/go-ipfs-cmdkit/files"
+	ft "gx/ipfs/QmU4x3742bvgfxJsByEDpBnifJqjJdV6x528co4hwKCn46/go-unixfs"
+	uio "gx/ipfs/QmU4x3742bvgfxJsByEDpBnifJqjJdV6x528co4hwKCn46/go-unixfs/io"
+	dag "gx/ipfs/QmcBoNcAP6qDjgRBew7yjvCqHq7p5jMstE44jPUBWBxzsV/go-merkledag"
+	ipld "gx/ipfs/QmdDXJs4axxefSPgK6Y1QhpJWKuDPnGJiqgq4uncb4rFHL/go-ipld-format"
+)
+
+// Number to file to prefetch in directories
+// TODO: should we allow setting this via context hint?
+const prefetchFiles = 4
+
+// TODO: this probably belongs in go-unixfs (and could probably replace a chunk of it's interface in the long run)
+
+type sizeInfo struct {
+	size int64
+	name string
+	modTime time.Time
+}
+
+func (s *sizeInfo) Name() string {
+	return s.name
+}
+
+func (s *sizeInfo) Size() int64 {
+	return s.size
+}
+
+func (s *sizeInfo) Mode() os.FileMode {
+	return 0444 // all read
+}
+
+func (s *sizeInfo) ModTime() time.Time {
+	return s.modTime
+}
+
+func (s *sizeInfo) IsDir() bool {
+ return false
+}
+
+func (s *sizeInfo) Sys() interface{} {
+	return nil
+}
+
+type ufsDirectory struct {
+	ctx context.Context
+	dserv ipld.DAGService
+
+	files chan *ipld.Link
+
+	name string
+	path string
+}
+
+func (d *ufsDirectory) Close() error {
+	return files.ErrNotReader
+}
+
+func (d *ufsDirectory) Read(_ []byte) (int, error) {
+	return 0, files.ErrNotReader
+}
+
+func (d *ufsDirectory) FileName() string {
+	return d.name
+}
+
+func (d *ufsDirectory) FullPath() string {
+	return d.path
+}
+
+func (d *ufsDirectory) IsDirectory() bool {
+	return true
+}
+
+func (d *ufsDirectory) NextFile() (files.File, error) {
+	l, ok := <-d.files
+	if !ok {
+		return nil, io.EOF
+	}
+
+	nd, err := l.GetNode(d.ctx, d.dserv)
+	if err != nil {
+		return nil, err
+	}
+
+	return newUnixfsFile(d.ctx, d.dserv, nd, l.Name, d)
+}
+
+type ufsFile struct {
+	uio.DagReader
+
+	name string
+	path string
+}
+
+func (f *ufsFile) IsDirectory() bool {
+	return false
+}
+
+func (f *ufsFile) NextFile() (files.File, error) {
+	return nil, files.ErrNotDirectory
+}
+
+func (f *ufsFile) FileName() string {
+	return f.name
+}
+
+func (f *ufsFile) FullPath() string {
+	return f.path
+}
+
+func (f *ufsFile) Size() (int64, error) {
+	return int64(f.DagReader.Size()), nil
+}
+
+func newUnixfsDir(ctx context.Context, dserv ipld.DAGService, nd ipld.Node, name string, path string) (files.File, error) {
+	dir, err := uio.NewDirectoryFromNode(dserv, nd)
+	if err != nil {
+		return nil, err
+	}
+
+	fileCh := make(chan *ipld.Link, prefetchFiles)
+	go func() {
+		dir.ForEachLink(ctx, func(link *ipld.Link) error {
+			select {
+			case fileCh <- link:
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+			return nil
+		})
+
+		close(fileCh)
+	}()
+
+	return &ufsDirectory{
+		ctx: ctx,
+		dserv: dserv,
+
+		files: fileCh,
+
+		name: name,
+		path: path,
+	}, nil
+}
+
+func newUnixfsFile(ctx context.Context, dserv ipld.DAGService, nd ipld.Node, name string, parent files.File) (files.File, error) {
+	path := name
+	if parent != nil {
+		path = gopath.Join(parent.FullPath(), name)
+	}
+
+	switch dn := nd.(type) {
+	case *dag.ProtoNode:
+		fsn, err := ft.FSNodeFromBytes(nd.RawData())
+		if err != nil {
+			return nil, err
+		}
+		if fsn.IsDir() {
+			return newUnixfsDir(ctx, dserv, nd, name, path)
+		}
+
+	case *dag.RawNode:
+
+		r := ioutil.NopCloser(bytes.NewReader(dn.RawData()))
+		fi := &sizeInfo{
+			size: int64(len(dn.RawData())),
+		}
+
+		return files.NewReaderFile("", "", r, fi), nil
+	default:
+		return nil, errors.New("unknown node type")
+	}
+
+	dr, err := uio.NewDagReader(ctx, nd, dserv)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ufsFile{
+		DagReader: dr,
+
+		name: name,
+		path: path,
+	}, nil
+}
+
+
+var _ os.FileInfo = &sizeInfo{}

core/coreapi/unixfs.go

@@ -110,6 +110,15 @@ func (api *UnixfsAPI) Add(ctx context.Context, files files.File, opts ...options
 	return coreiface.IpfsPath(nd.Cid()), nil
 }
 
+func (api *UnixfsAPI) Get(ctx context.Context, p coreiface.Path) (files.File, error) {
+	nd, err := api.core().ResolveNode(ctx, p)
+	if err != nil {
+		return nil, err
+	}
+
+	return newUnixfsFile(ctx, api.node.DAG, nd, "", nil)
+}
+
 // Cat returns the data contained by an IPFS or IPNS object(s) at path `p`.
 func (api *UnixfsAPI) Cat(ctx context.Context, p coreiface.Path) (coreiface.Reader, error) {
 	dget := api.node.DAG // TODO: use a session here once routing perf issues are resolved