vfs: Implement Read support (#14)

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

fuse/hanwen/fs.go

@@ -161,8 +161,12 @@ func (fs *FS) Lookup(cancel <-chan struct{}, header *fuse.InHeader, name string,
 	}
 
 	node, err := fs.fs.GetEntry(ino.ID, name)
+	if err != nil && errors.Is(err, services.ErrObjectNotExist) {
+		return fuse.ENOENT
+	}
 	if err != nil {
-		return
+		fs.logger.Error("get entry", zap.Error(err))
+		return fuse.EAGAIN
 	}
 	if node == nil {
 		return fuse.ENOENT
@@ -342,7 +346,19 @@ func (fs *FS) Open(cancel <-chan struct{}, input *fuse.OpenIn, out *fuse.OpenOut
 }
 
 func (fs *FS) Read(cancel <-chan struct{}, input *fuse.ReadIn, buf []byte) (fuse.ReadResult, fuse.Status) {
-	panic("implement me")
+	fh, err := fs.fs.GetFileHandle(input.Fh)
+	if err != nil {
+		fs.logger.Error("get file handle", zap.Error(err))
+		return nil, fuse.EAGAIN
+	}
+
+	n, err := fh.Read(input.Offset, buf)
+	if err != nil {
+		fs.logger.Error("read", zap.Error(err))
+		return nil, fuse.EAGAIN
+	}
+	return fuse.ReadResultData(buf[:n]), fuse.OK
+
 }
 
 func (fs *FS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekOut) fuse.Status {

vfs/file.go

@@ -1,11 +1,19 @@
 package vfs
 
 import (
+	"go.uber.org/zap"
 	"sync"
 
+	"github.com/Xuanwo/go-bufferpool"
+	"github.com/beyondstorage/go-storage/v4/pairs"
+
 	"github.com/beyondstorage/beyond-fs/meta"
 )
 
+var (
+	fileBufPool = bufferpool.New(4 * 1024 * 1024)
+)
+
 type fileHandleMap struct {
 	lock sync.Mutex
 	m    map[uint64]*FileHandle
@@ -44,4 +52,41 @@ type FileHandle struct {
 	ino  *Inode
 	fs   *FS
 	meta meta.Service
+
+	mu     sync.Mutex
+	buf    *bufferpool.Buffer
+	size   uint64
+	offset uint64
+}
+
+func (fh *FileHandle) GetInode() *Inode {
+	return fh.ino
+}
+
+func (fh *FileHandle) Read(offset uint64, buf []byte) (n int, err error) {
+	size := fh.size
+	if size > uint64(len(buf)) {
+		size = uint64(len(buf))
+	}
+
+	fh.mu.Lock()
+	defer fh.mu.Unlock()
+
+	fh.buf.Reset()
+
+	fh.fs.logger.Info("read data",
+		zap.String("path", fh.ino.Path),
+		zap.Uint64("offset", offset),
+		zap.Uint64("size", size))
+	byteRead, err := fh.fs.s.Read(fh.ino.Path, fh.buf,
+		pairs.WithOffset(int64(offset)),
+		pairs.WithSize(int64(size)))
+	if err != nil {
+		fh.fs.logger.Error("read underlying", zap.Error(err))
+		return
+	}
+
+	copy(buf, fh.buf.Bytes()[:byteRead])
+	fh.offset += uint64(byteRead)
+	return int(byteRead), nil
 }

vfs/fs.go

@@ -2,6 +2,7 @@ package vfs
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"time"
 
@@ -128,6 +129,34 @@ func (fs *FS) Delete(parent uint64, name string) (err error) {
 	return
 }
 
+func (fs *FS) Stat(parent uint64, name string) (ino *Inode, err error) {
+	p, err := fs.GetInode(parent)
+	if err != nil {
+		return
+	}
+
+	path := p.GetEntryPath(name)
+	o, err := fs.s.Stat(path)
+	if err != nil && errors.Is(err, services.ErrObjectNotExist) {
+		// FIXME: we need to use stat with ModeDir instead.
+		o, err = fs.s.Stat(path + "/")
+		if err != nil {
+			return nil, err
+		}
+		o.Path = path
+		o.Mode = types.ModeDir
+	}
+	if err != nil {
+		return nil, err
+	}
+	ino = newInode(p.ID, o)
+	err = fs.SetInode(ino)
+	if err != nil {
+		return
+	}
+	return
+}
+
 func (fs *FS) DeleteDir(path string) (err error) {
 	panic("implement me")
 }
@@ -138,6 +167,10 @@ func (fs *FS) CreateFileHandle(ino *Inode) (fh *FileHandle, err error) {
 		ino:  ino,
 		fs:   fs,
 		meta: fs.meta,
+
+		buf:    fileBufPool.Get(),
+		size:   ino.Size,
+		offset: 0,
 	}
 	fs.fhm.Set(fh.ID, fh)
 	return fh, nil
@@ -239,7 +272,8 @@ func (fs *FS) GetEntry(parent uint64, name string) (ino *Inode, err error) {
 		return nil, fmt.Errorf("get entry: %w", err)
 	}
 	if bs == nil {
-		return nil, nil
+		// Try get from underlying storage
+		return fs.Stat(parent, name)
 	}
 
 	ino = &Inode{}