From 2a8de96773a730bee37d7301ff892ec0fed936f3 Mon Sep 17 00:00:00 2001
From: Yannick Ulrich <yannick.ulrich@durham.ac.uk>
Date: Sun, 19 Feb 2023 19:00:20 +0000
Subject: [PATCH] Implemented Write

---
 fuse/main.go | 76 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 61 insertions(+), 15 deletions(-)

diff --git a/fuse/main.go b/fuse/main.go
index 769f593..a0643bb 100644
--- a/fuse/main.go
+++ b/fuse/main.go
@@ -202,12 +202,12 @@ func (n *ITNode) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*
 	return nil, syscall.ENOENT
 }
 
-type bytesFileHandle struct {
+type bytesFileReadHandle struct {
 	content []byte
 }
-var _ = (fs.FileReader)((*bytesFileHandle)(nil))
+var _ = (fs.FileReader)((*bytesFileReadHandle)(nil))
 
-func (fh *bytesFileHandle) Read(ctx context.Context, dest []byte, off int64) (fuse.ReadResult, syscall.Errno) {
+func (fh *bytesFileReadHandle) Read(ctx context.Context, dest []byte, off int64) (fuse.ReadResult, syscall.Errno) {
 	end := off + int64(len(dest))
 	if end > int64(len(fh.content)) {
 		end = int64(len(fh.content))
@@ -215,32 +215,78 @@ func (fh *bytesFileHandle) Read(ctx context.Context, dest []byte, off int64) (fu
 	return fuse.ReadResultData(fh.content[off:end]), 0
 }
 
+type bytesFileWriteHandle struct {
+	content []byte
+	path string
+}
+
+var _ = (fs.FileWriter)((*bytesFileWriteHandle)(nil))
+func (fh *bytesFileWriteHandle) Write(ctx context.Context, data []byte, off int64) (written uint32, errno syscall.Errno) {
+	if off != int64(len(fh.content)) {
+	}
+	fh.content = append(fh.content[:], data[:]...)
+	return uint32(len(data)), 0
+}
+
+var _ = (fs.FileFlusher)((*bytesFileWriteHandle)(nil))
+func (fh *bytesFileWriteHandle) Flush(ctx context.Context) (errno syscall.Errno) {
+	fp, err := myfs.Create(fh.path, uint32(len(fh.content)))
+	if err != nil {
+		return syscall.EROFS
+	}
+	nread, err := fp.Write(fh.content)
+	if err != nil || nread != len(fh.content) {
+		return syscall.EROFS
+	}
+
+	return 0
+}
+
+var _ = (fs.NodeSetattrer)((*ITNode)(nil))
+func (bn *ITNode) Setattr(ctx context.Context, fh fs.FileHandle, in *fuse.SetAttrIn, out *fuse.AttrOut) syscall.Errno {
+	out.Size = 0;
+	out.Mtime = 0;
+	return 0
+}
+
 var _ = (fs.NodeOpener)((*ITNode)(nil))
 func (f *ITNode) Open(ctx context.Context, openFlags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
 	switch f.kind {
 	case 2:
 		// FS file
-		fp, err := myfs.Open(f.path)
-		if err != nil {
+		if openFlags&syscall.O_RDWR != 0 {
 			return nil, 0, syscall.EROFS
 		}
 
-		buf := make([]byte, f.self.size);
-		nread, err := fp.Read(buf)
-		if err != nil || nread != int(f.self.size) {
-			return nil, 0, syscall.EROFS
-		}
+		if openFlags & syscall.O_WRONLY != 0 {
+			fh = &bytesFileWriteHandle{
+				path : f.path,
+				content : make([]byte, 0),
+			}
+			return fh, fuse.FOPEN_DIRECT_IO, 0
+		} else {
+			fp, err := myfs.Open(f.path)
+			if err != nil {
+				return nil, 0, syscall.EROFS
+			}
 
-		fh = &bytesFileHandle{
-			content: buf,
+			buf := make([]byte, f.self.size);
+			nread, err := fp.Read(buf)
+			if err != nil || nread != int(f.self.size) {
+				return nil, 0, syscall.EROFS
+			}
+
+			fh = &bytesFileReadHandle{
+				content: buf,
+			}
+			return fh, fuse.FOPEN_DIRECT_IO, 0
 		}
-		return fh, fuse.FOPEN_DIRECT_IO, 0
 
 	case 3:
 		// Device file
 
 		// disallow writes
-		if fuseFlags&(syscall.O_RDWR|syscall.O_WRONLY) != 0 {
+		if openFlags&(syscall.O_RDWR|syscall.O_WRONLY) != 0 {
 			return nil, 0, syscall.EROFS
 		}
 
@@ -251,7 +297,7 @@ func (f *ITNode) Open(ctx context.Context, openFlags uint32) (fh fs.FileHandle,
 					return nil, 0, syscall.EROFS
 				}
 
-				fh = &bytesFileHandle{
+				fh = &bytesFileReadHandle{
 					content: ans,
 				}
 				return fh, fuse.FOPEN_DIRECT_IO, 0