pkg: Implement wrapper for fs.FS and http.FileSystem (#538)

* pkg: Implement wrapper for fs.FS

Signed-off-by: Xuanwo <github@xuanwo.io>

* Rename tp fswrap

Signed-off-by: Xuanwo <github@xuanwo.io>

* Fix build

Signed-off-by: Xuanwo <github@xuanwo.io>

* Add convert function

Signed-off-by: Xuanwo <github@xuanwo.io>

pkg/fswrap/doc.go

@@ -0,0 +1,5 @@
+/*
+package iofswrap is a wrapper that convert go-storage services to fs.FS.
+*/
+
+package fswrap

pkg/fswrap/fileinfo.go

@@ -0,0 +1,52 @@
+package fswrap
+
+import (
+	"os"
+	"time"
+
+	"github.com/aos-dev/go-storage/v3/types"
+)
+
+type fileInfoWrapper struct {
+	object *types.Object
+}
+
+func (o fileInfoWrapper) Name() string {
+	return o.object.Path
+}
+
+func (o fileInfoWrapper) Size() int64 {
+	return o.object.MustGetContentLength()
+}
+
+func (o fileInfoWrapper) Mode() os.FileMode {
+	return formatFileMode(o.object.Mode)
+}
+
+func (o fileInfoWrapper) ModTime() time.Time {
+	return o.object.MustGetLastModified()
+}
+
+func (o fileInfoWrapper) IsDir() bool {
+	return o.object.Mode.IsDir()
+}
+
+// Sys will return internal Object.
+func (o fileInfoWrapper) Sys() interface{} {
+	return o.object
+}
+
+func formatFileMode(om types.ObjectMode) os.FileMode {
+	var m os.FileMode
+
+	if om.IsDir() {
+		m |= os.ModeDir
+	}
+	if om.IsAppend() {
+		m |= os.ModeAppend
+	}
+	if om.IsLink() {
+		m |= os.ModeSymlink
+	}
+	return m
+}

pkg/fswrap/httpfs.go

@@ -0,0 +1,125 @@
+package fswrap
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"net/http"
+	"os"
+
+	"github.com/aos-dev/go-storage/v3/pairs"
+	"github.com/aos-dev/go-storage/v3/types"
+)
+
+var (
+	_ http.FileSystem = httpFsWrapper{}
+
+	_ http.File = httpFileWrapper{}
+)
+
+// HttpFs convert a Storager to http.FileSystem
+func HttpFs(s types.Storager) http.FileSystem {
+	return httpFsWrapper{s}
+}
+
+type httpFsWrapper struct {
+	store types.Storager
+}
+
+func (h httpFsWrapper) Open(name string) (http.File, error) {
+	o, err := h.store.Stat(name)
+	if err != nil {
+		return nil, err
+	}
+	return &httpFileWrapper{store: h.store, object: o}, nil
+}
+
+type httpFileWrapper struct {
+	store  types.Storager
+	object *types.Object
+
+	offset int64
+	buf    bytes.Buffer
+}
+
+func (h httpFileWrapper) Close() error {
+	h.store = nil
+	h.object = nil
+	h.offset = 0
+	return nil
+}
+
+func (h httpFileWrapper) Read(bs []byte) (int, error) {
+	size := int64(len(bs))
+
+	n, err := h.store.Read(h.object.Path, &h.buf, pairs.WithSize(size), pairs.WithOffset(h.offset))
+	if err != nil {
+		return int(n), err
+	}
+	h.offset += n
+
+	nn := copy(bs, h.buf.Bytes())
+	h.buf.Reset() // Reset internal buffer after copy
+	return nn, nil
+}
+
+func (h httpFileWrapper) Seek(offset int64, whence int) (int64, error) {
+	size := h.object.MustGetContentLength()
+
+	switch whence {
+	case io.SeekStart:
+		h.offset = offset
+	case io.SeekCurrent:
+		h.offset += offset
+	case io.SeekEnd:
+		// TODO: Do we need to check value here?
+		h.offset = size - offset
+	}
+	return h.offset, nil
+}
+
+func (h httpFileWrapper) Readdir(count int) ([]os.FileInfo, error) {
+	if !h.object.Mode.IsDir() {
+		return nil, os.ErrInvalid
+	}
+
+	it, err := h.store.List(h.object.Path, pairs.WithListMode(types.ListModeDir))
+	if err != nil {
+		return nil, err
+	}
+
+	// Change the meaning of n for the implementation below.
+	//
+	// The n above was for the public interface of "if n <= 0,
+	// Readdir returns all the FileInfo from the directory in a
+	// single slice".
+	//
+	// But below, we use only negative to mean looping until the
+	// end and positive to mean bounded, with positive
+	// terminating at 0.
+	if count == 0 {
+		count = -1
+	}
+
+	fi := make([]os.FileInfo, 0)
+	for count != 0 {
+		o, err := it.Next()
+		if err != nil && errors.Is(err, types.IterateDone) {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		fi = append(fi, fileInfoWrapper{o})
+
+		if count > 0 {
+			count--
+		}
+	}
+	return fi, nil
+}
+
+func (h httpFileWrapper) Stat() (os.FileInfo, error) {
+	return &fileInfoWrapper{object: h.object}, nil
+}

pkg/fswrap/iofs.go

@@ -0,0 +1,168 @@
+//+build go1.16
+
+package fswrap
+
+import (
+	"bytes"
+	"errors"
+	"io/fs"
+	"path"
+
+	"github.com/aos-dev/go-storage/v3/pairs"
+	"github.com/aos-dev/go-storage/v3/types"
+)
+
+var (
+	_ fs.FS         = fsWrapper{}
+	_ fs.GlobFS     = fsWrapper{}
+	_ fs.ReadDirFS  = fsWrapper{}
+	_ fs.ReadFileFS = fsWrapper{}
+	_ fs.StatFS     = fsWrapper{}
+	_ fs.SubFS      = fsWrapper{}
+
+	_ fs.File = &fileWrapper{}
+
+	_ fs.FileInfo = &fileInfoWrapper{}
+
+	_ fs.DirEntry = &dirEntryWrapper{}
+)
+
+// Fs convert a Storager to fs.FS
+func Fs(s types.Storager) fs.FS {
+	return fsWrapper{s}
+}
+
+type fsWrapper struct {
+	store types.Storager
+}
+
+func (w fsWrapper) Open(name string) (fs.File, error) {
+	o, err := w.store.Stat(name)
+	if err != nil {
+		return nil, err
+	}
+	return &fileWrapper{store: w.store, object: o}, nil
+}
+
+func (w fsWrapper) Glob(name string) ([]string, error) {
+	it, err := w.store.List("", pairs.WithListMode(types.ListModePrefix))
+	if err != nil {
+		return nil, err
+	}
+
+	s := make([]string, 0)
+	for {
+		o, err := it.Next()
+		if err != nil && errors.Is(err, types.IterateDone) {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		ok, err := path.Match(name, o.Path)
+		if err != nil {
+			return nil, err
+		}
+		if ok {
+			s = append(s, o.Path)
+		}
+	}
+	return s, nil
+}
+
+func (w fsWrapper) ReadDir(name string) ([]fs.DirEntry, error) {
+	it, err := w.store.List(name, pairs.WithListMode(types.ListModeDir))
+	if err != nil {
+		return nil, err
+	}
+
+	ds := make([]fs.DirEntry, 0)
+	for {
+		o, err := it.Next()
+		if err != nil && errors.Is(err, types.IterateDone) {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		ds = append(ds, dirEntryWrapper{o})
+	}
+	return ds, nil
+}
+
+func (w fsWrapper) ReadFile(name string) ([]byte, error) {
+	var buf bytes.Buffer
+
+	_, err := w.store.Read(name, &buf)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func (w fsWrapper) Stat(name string) (fs.FileInfo, error) {
+	o, err := w.store.Stat(name)
+	if err != nil {
+		return nil, err
+	}
+	return &fileInfoWrapper{object: o}, nil
+}
+
+func (w fsWrapper) Sub(dir string) (fs.FS, error) {
+	panic("implement me")
+}
+
+type fileWrapper struct {
+	store  types.Storager
+	object *types.Object
+
+	offset int64
+	buf    bytes.Buffer
+}
+
+func (o fileWrapper) Stat() (fs.FileInfo, error) {
+	return &fileInfoWrapper{o.object}, nil
+}
+
+func (o fileWrapper) Read(bs []byte) (int, error) {
+	size := int64(len(bs))
+
+	n, err := o.store.Read(o.object.Path, &o.buf, pairs.WithSize(size), pairs.WithOffset(o.offset))
+	if err != nil {
+		return int(n), err
+	}
+	o.offset += n
+
+	nn := copy(bs, o.buf.Bytes())
+	o.buf.Reset() // Reset internal buffer after copy
+	return nn, nil
+}
+
+func (o fileWrapper) Close() error {
+	o.store = nil
+	o.object = nil
+	o.offset = 0
+	return nil
+}
+
+type dirEntryWrapper struct {
+	object *types.Object
+}
+
+func (d dirEntryWrapper) Name() string {
+	return d.object.Path
+}
+
+func (d dirEntryWrapper) IsDir() bool {
+	return d.object.Mode.IsDir()
+}
+
+func (d dirEntryWrapper) Type() fs.FileMode {
+	return formatFileMode(d.object.Mode)
+}
+
+func (d dirEntryWrapper) Info() (fs.FileInfo, error) {
+	return &fileInfoWrapper{d.object}, nil
+}