Prepare read API for splicing.

fuse/api.go

@@ -77,6 +77,7 @@ type FsNode interface {
 	StatFs() *StatfsOut
 }
 
+
 // A filesystem API that uses paths rather than inodes.  A minimal
 // file system should have at least a functional GetAttr method.
 // Typically, each call happens in its own goroutine, so take care to
@@ -161,7 +162,7 @@ type File interface {
 	// the inner file here.
 	InnerFile() File
 
-	Read(dest []byte, off int64) ([]byte, Status)
+	Read(dest []byte, off int64) ReadResult
 	Write(data []byte, off int64) (written uint32, code Status)
 	Flush() Status
 	Release()
@@ -278,7 +279,7 @@ type RawFileSystem interface {
 	// File handling.
 	Create(out *raw.CreateOut, header *raw.InHeader, input *raw.CreateIn, name string) (code Status)
 	Open(out *raw.OpenOut, header *raw.InHeader, input *raw.OpenIn) (status Status)
-	Read(*raw.InHeader, *ReadIn, []byte) ([]byte, Status)
+	Read(*raw.InHeader, *ReadIn, []byte) ReadResult 
 
 	Release(header *raw.InHeader, input *raw.ReleaseIn)
 	Write(*raw.InHeader, *WriteIn, []byte) (written uint32, code Status)

fuse/copy.go

@@ -30,24 +30,26 @@ func CopyFile(srcFs, destFs FileSystem, srcFile, destFile string, context *Conte
 	buf := make([]byte, 128 * (1 << 10))
 	off := int64(0)
 	for {
-		data, code := src.Read(buf, off)
-		if !code.Ok() {
-			return code
+		res := src.Read(buf, off)
+		if !res.Ok() {
+			return res.Status
 		}
-		if len(data) == 0 {
+		res.Read(buf)
+		
+		if len(res.Data) == 0 {
 			break
 		}
-		n, code := dst.Write(data, off)
+		n, code := dst.Write(res.Data, off)
 		if !code.Ok() {
 			return code
 		}
-		if int(n) < len(data) {
+		if int(n) < len(res.Data) {
 			return EIO
 		}
-		if len(data) < len(buf) {
+		if len(res.Data) < len(buf) {
 			break
 		}
-		off += int64(len(data))
+		off += int64(len(res.Data))
 	}
 	return OK
 }

fuse/defaultfile.go

@@ -8,6 +8,8 @@ import (
 
 var _ = log.Println
 
+var _ = (File)((*DefaultFile)(nil))
+
 func (f *DefaultFile) SetInode(*Inode) {
 }
 
@@ -19,8 +21,8 @@ func (f *DefaultFile) String() string {
 	return "DefaultFile"
 }
 
-func (f *DefaultFile) Read(buf []byte, off int64) ([]byte, Status) {
-	return nil, ENOSYS
+func (f *DefaultFile) Read(buf []byte, off int64) ReadResult {
+	return ReadResult{Status: ENOSYS}
 }
 
 func (f *DefaultFile) Write(data []byte, off int64) (uint32, Status) {

fuse/defaultraw.go

@@ -97,8 +97,8 @@ func (fs *DefaultRawFileSystem) OpenDir(out *raw.OpenOut, header *raw.InHeader,
 	return ENOSYS
 }
 
-func (fs *DefaultRawFileSystem) Read(header *raw.InHeader, input *ReadIn, buf []byte) ([]byte, Status) {
-	return nil, ENOSYS
+func (fs *DefaultRawFileSystem) Read(header *raw.InHeader, input *ReadIn, buf []byte) ReadResult {
+	return ReadResult{}
 }
 
 func (fs *DefaultRawFileSystem) Release(header *raw.InHeader, input *raw.ReleaseIn) {

fuse/files.go

@@ -2,7 +2,6 @@ package fuse
 
 import (
 	"fmt"
-	"io"
 	"os"
 	"syscall"
 )
@@ -40,13 +39,15 @@ func NewDataFile(data []byte) *DataFile {
 	return f
 }
 
-func (f *DataFile) Read(buf []byte, off int64) ([]byte, Status) {
+func (f *DataFile) Read(buf []byte, off int64) (res ReadResult) {
 	end := int(off) + int(len(buf))
 	if end > len(f.data) {
 		end = len(f.data)
 	}
 
-	return f.data[off:end], OK
+	res.Data = f.data[off:end]
+	res.Status = OK
+	return res
 }
 
 ////////////////
@@ -66,8 +67,8 @@ func (f *DevNullFile) String() string {
 	return "DevNullFile"
 }
 
-func (f *DevNullFile) Read(buf []byte, off int64) ([]byte, Status) {
-	return nil, OK
+func (f *DevNullFile) Read(buf []byte, off int64) ReadResult {
+	return ReadResult{}
 }
 
 func (f *DevNullFile) Write(content []byte, off int64) (uint32, Status) {
@@ -99,12 +100,13 @@ func (f *LoopbackFile) String() string {
 	return fmt.Sprintf("LoopbackFile(%s)", f.File.Name())
 }
 
-func (f *LoopbackFile) Read(buf []byte, off int64) ([]byte, Status) {
-	n, err := f.File.ReadAt(buf, off)
-	if err == io.EOF {
-		err = nil
+func (f *LoopbackFile) Read(buf []byte, off int64) (res ReadResult) {
+	return ReadResult{
+		Fd: f.File.Fd(),
+		FdOff: off,
+		FdSize:len(buf),
+		Status: OK,
 	}
-	return buf[:n], ToStatus(err)
 }
 
 func (f *LoopbackFile) Write(data []byte, off int64) (uint32, Status) {

fuse/fsetattr_test.go

@@ -22,8 +22,9 @@ func (f *MutableDataFile) String() string {
 	return "MutableDataFile"
 }
 
-func (f *MutableDataFile) Read(buf []byte, off int64) ([]byte, Status) {
-	return f.data[off : off+int64(len(buf))], OK
+func (f *MutableDataFile) Read(buf []byte, off int64) (r ReadResult) {
+	r.Data = f.data[off : off+int64(len(buf))]
+	return r	
 }
 
 func (f *MutableDataFile) Write(d []byte, off int64) (uint32, Status) {

fuse/fsops.go

@@ -350,7 +350,7 @@ func (c *FileSystemConnector) Write(header *raw.InHeader, input *WriteIn, data [
 	return opened.WithFlags.File.Write(data, int64(input.Offset))
 }
 
-func (c *FileSystemConnector) Read(header *raw.InHeader, input *ReadIn, buf []byte) ([]byte, Status) {
+func (c *FileSystemConnector) Read(header *raw.InHeader, input *ReadIn, buf []byte) (ReadResult) {
 	node := c.toInode(header.NodeId)
 	opened := node.mount.getOpenedFile(input.Fh)
 	

fuse/lockingfs.go

@@ -276,7 +276,7 @@ func (fs *LockingRawFileSystem) ReleaseDir(header *raw.InHeader, h *raw.ReleaseI
 	fs.RawFileSystem.ReleaseDir(header, h)
 }
 
-func (fs *LockingRawFileSystem) Read(header *raw.InHeader, input *ReadIn, buf []byte) ([]byte, Status) {
+func (fs *LockingRawFileSystem) Read(header *raw.InHeader, input *ReadIn, buf []byte) ReadResult {
 	defer fs.locked()()
 	return fs.RawFileSystem.Read(header, input, buf)
 }

fuse/mountstate.go

@@ -322,6 +322,10 @@ func (ms *MountState) handleRequest(req *request) {
 }
 
 func (ms *MountState) AllocOut(req *request, size uint32) []byte {
+	if cap(req.bufferPoolOutputBuf) >= int(size) {
+		req.bufferPoolOutputBuf = req.bufferPoolOutputBuf[:size]
+		return req.bufferPoolOutputBuf 
+	}
 	if req.bufferPoolOutputBuf != nil {
 		ms.buffers.FreeBuffer(req.bufferPoolOutputBuf)
 	}
@@ -336,7 +340,7 @@ func (ms *MountState) write(req *request) Status {
 		return OK
 	}
 
-	header, data := req.serialize()
+	header := req.serializeHeader()
 	if ms.Debug {
 		log.Println(req.OutputDebug())
 	}
@@ -348,16 +352,30 @@ func (ms *MountState) write(req *request) Status {
 	if header == nil {
 		return OK
 	}
-	var err error
-	if data == nil {
-		_, err = ms.mountFile.Write(header)
-	} else {
-		_, err = Writev(int(ms.mountFile.Fd()), [][]byte{header, data})
+
+	if req.flatData.Size() == 0 {
+		_, err := ms.mountFile.Write(header)
+		return ToStatus(err)
+	}
+
+	if req.flatData.FdSize > 0 {
+		if ms.TrySplice(req) {
+			return OK
+		} else {
+			buf := ms.AllocOut(req, uint32(req.flatData.FdSize))
+			req.flatData.Read(buf)
+		}
 	}
 
+	_, err := Writev(int(ms.mountFile.Fd()), [][]byte{header, req.flatData.Data})
 	return ToStatus(err)
 }
 
+func (ms *MountState) TrySplice(req *request) bool {
+	// TODO - implement.
+	return false
+}
+
 func (ms *MountState) writeInodeNotify(entry *raw.NotifyInvalInodeOut) Status {
 	req := request{
 		inHeader: &raw.InHeader{
@@ -392,7 +410,7 @@ func (ms *MountState) writeEntryNotify(parent uint64, name string) Status {
 	// terminating null byte is missing.
 	nameBytes := []byte(name + "\000")
 	req.outData = unsafe.Pointer(entry)
-	req.flatData = nameBytes
+	req.flatData.Data = nameBytes
 	result := ms.write(&req)
 
 	if ms.Debug {

fuse/opcode.go

@@ -123,7 +123,7 @@ func doReadDir(state *MountState, req *request) {
 	entries := NewDirEntryList(buf, uint64(in.Offset))
 	
 	code := state.fileSystem.ReadDir(entries, req.inHeader, in)
-	req.flatData = entries.Bytes()
+	req.flatData.Data = entries.Bytes()
 	req.status = code
 }
 
@@ -192,7 +192,7 @@ func doGetXAttr(state *MountState, req *request) {
 		return
 	}
 
-	req.flatData = data
+	req.flatData.Data = data
 }
 
 func doGetAttr(state *MountState, req *request) {
@@ -223,7 +223,7 @@ func doBatchForget(state *MountState, req *request) {
 }
 
 func doReadlink(state *MountState, req *request) {
-	req.flatData, req.status = state.fileSystem.Readlink(req.inHeader)
+	req.flatData.Data, req.status = state.fileSystem.Readlink(req.inHeader)
 }
 
 func doLookup(state *MountState, req *request) {
@@ -260,7 +260,13 @@ func doLink(state *MountState, req *request) {
 func doRead(state *MountState, req *request) {
 	in := (*ReadIn)(req.inData)
 	buf := state.AllocOut(req, in.Size)
-	req.flatData, req.status = state.fileSystem.Read(req.inHeader, in, buf)
+	res := state.fileSystem.Read(req.inHeader, in, buf)
+	if res.Ok() {
+		res.Read(buf)
+	}
+	
+	req.flatData = res
+	req.status = res.Status
 }
 
 func doFlush(state *MountState, req *request) {

fuse/read.go

+package fuse
+
+import (
+	"io"
+	"syscall"
+)
+
+type ReadResult struct {
+	Status
+	Data []byte
+
+	// If Data is nil and Status OK, splice from the following
+	// file.
+	Fd   uintptr
+	FdOff  int64
+	FdSize int
+}
+
+func (r *ReadResult) Clear() {
+	*r = ReadResult{}
+}
+
+func (r *ReadResult) Size() int {
+	if r.Data != nil {
+		return len(r.Data)
+	}
+	return r.FdSize
+}
+
+func (r *ReadResult) Read(buf []byte) Status {
+	if r.Data != nil || !r.Ok() {
+		return r.Status
+	}
+	if len(buf) < r.FdSize {
+		r.Status = ERANGE
+		return ERANGE
+	}
+
+	n, err := syscall.Pread(int(r.Fd), buf[:r.FdSize], r.FdOff)
+	if err == io.EOF {
+		err = nil
+	}
+	r.Status = ToStatus(err)
+	if r.Ok() {
+		r.Data = buf[:n]
+	}
+	r.Fd = 0
+	r.FdOff = 0
+	r.FdSize = 0
+	
+	return r.Status
+}

fuse/request.go

@@ -26,8 +26,8 @@ type request struct {
 	// Unstructured data, a pointer to the relevant XxxxOut struct.
 	outData  unsafe.Pointer
 	status   Status
-	flatData []byte
-
+	flatData ReadResult
+	
 	// Start timestamp for timing info.
 	startNs    int64
 	preWriteNs int64
@@ -58,7 +58,7 @@ func (r *request) clear() {
 	r.filenames = nil
 	r.outData = nil
 	r.status = OK
-	r.flatData = nil
+	r.flatData.Clear()
 	r.preWriteNs = 0
 	r.startNs = 0
 	r.handler = nil
@@ -100,12 +100,12 @@ func (r *request) OutputDebug() string {
 	}
 
 	flatStr := ""
-	if len(r.flatData) > 0 {
+	if r.flatData.Size() > 0 {
 		if r.handler.FileNameOut {
-			s := strings.TrimRight(string(r.flatData), "\x00")
+			s := strings.TrimRight(string(r.flatData.Data), "\x00")
 			flatStr = fmt.Sprintf(" %q", s)
 		} else {
-			flatStr = fmt.Sprintf(" %d bytes data\n", len(r.flatData))
+			flatStr = fmt.Sprintf(" %d bytes data\n", r.flatData.Size())
 		}
 	}
 
@@ -175,7 +175,7 @@ func (r *request) parse() {
 	r.outData = unsafe.Pointer(&r.outBuf[sizeOfOutHeader])
 }
 
-func (r *request) serialize() (header []byte, data []byte) {
+func (r *request) serializeHeader() (header []byte) {
 	dataLength := r.handler.OutputSize
 	if r.outData == nil || r.status > OK {
 		dataLength = 0
@@ -187,11 +187,11 @@ func (r *request) serialize() (header []byte, data []byte) {
 	o.Unique = r.inHeader.Unique
 	o.Status = int32(-r.status)
 	o.Length = uint32(
-		int(sizeOfOutHeader) + int(dataLength) + int(len(r.flatData)))
+		int(sizeOfOutHeader) + int(dataLength) + r.flatData.Size())
 
 	var asSlice []byte
 	toSlice(&asSlice, r.outData, dataLength)
 	copy(header[sizeOfOutHeader:], asSlice)
-	return header, r.flatData
+	return header
 }