From 1b4a34cc7b6f1520582638ebe8afd24783f82125 Mon Sep 17 00:00:00 2001
From: Srdjan Rilak <srdjan.rilak@sbgenomics.com>
Date: Fri, 24 Nov 2017 12:44:41 +0100
Subject: [PATCH] Add CreateLink implementation

---
 conversions.go                          | 31 +++++++++++++++++++++++++
 fuseops/ops.go                          | 20 ++++++++++++++++
 fuseutil/file_system.go                 |  4 ++++
 fuseutil/not_implemented_file_system.go |  7 ++++++
 4 files changed, 62 insertions(+)

diff --git a/conversions.go b/conversions.go
index 6b0f16e..66be34f 100644
--- a/conversions.go
+++ b/conversions.go
@@ -420,6 +420,32 @@ func convertInMessage(
 			Flags:        fusekernel.InitFlags(in.Flags),
 		}
 
+	case fusekernel.OpLink:
+		type input fusekernel.LinkIn
+		in := (*input)(inMsg.Consume(unsafe.Sizeof(input{})))
+		if in == nil {
+			err = errors.New("Corrupt OpLink")
+			return
+		}
+
+		name := inMsg.ConsumeBytes(inMsg.Len())
+		i := bytes.IndexByte(name, '\x00')
+		if i < 0 {
+			err = errors.New("Corrupt OpLink")
+			return
+		}
+		name = name[:i]
+		if len(name) == 0 {
+			err = errors.New("Corrupt OpLink (Name not read)")
+			return
+		}
+
+		o = &fuseops.CreateLinkOp{
+			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:   string(name),
+			Target: fuseops.InodeID(in.Oldnodeid),
+		}
+
 	case fusekernel.OpRemovexattr:
 		buf := inMsg.ConsumeBytes(inMsg.Len())
 		n := len(buf)
@@ -647,6 +673,11 @@ func (c *Connection) kernelResponseForOp(
 		out := (*fusekernel.EntryOut)(m.Grow(size))
 		convertChildInodeEntry(&o.Entry, out)
 
+	case *fuseops.CreateLinkOp:
+		size := int(fusekernel.EntryOutSize(c.protocol))
+		out := (*fusekernel.EntryOut)(m.Grow(size))
+		convertChildInodeEntry(&o.Entry, out)
+
 	case *fuseops.RenameOp:
 		// Empty response
 
diff --git a/fuseops/ops.go b/fuseops/ops.go
index a939799..56fe89c 100644
--- a/fuseops/ops.go
+++ b/fuseops/ops.go
@@ -317,6 +317,26 @@ type CreateSymlinkOp struct {
 	Entry ChildInodeEntry
 }
 
+// Create a hard link to an inode. If the name already exists, the file system
+// should return EEXIST (cf. the notes on CreateFileOp and MkDirOp).
+type CreateLinkOp struct {
+	// The ID of parent directory inode within which to create the child hard
+	// link.
+	Parent InodeID
+
+	// The name of the new inode.
+	Name string
+
+	// The ID of the target inode.
+	Target InodeID
+
+	// Set by the file system: information about the inode that was created.
+	//
+	// The lookup count for the inode is implicitly incremented. See notes on
+	// ForgetInodeOp for more information.
+	Entry ChildInodeEntry
+}
+
 ////////////////////////////////////////////////////////////////////////
 // Unlinking
 ////////////////////////////////////////////////////////////////////////
diff --git a/fuseutil/file_system.go b/fuseutil/file_system.go
index fce16db..3a2a2cc 100644
--- a/fuseutil/file_system.go
+++ b/fuseutil/file_system.go
@@ -43,6 +43,7 @@ type FileSystem interface {
 	MkDir(context.Context, *fuseops.MkDirOp) error
 	MkNode(context.Context, *fuseops.MkNodeOp) error
 	CreateFile(context.Context, *fuseops.CreateFileOp) error
+	CreateLink(context.Context, *fuseops.CreateLinkOp) error
 	CreateSymlink(context.Context, *fuseops.CreateSymlinkOp) error
 	Rename(context.Context, *fuseops.RenameOp) error
 	RmDir(context.Context, *fuseops.RmDirOp) error
@@ -159,6 +160,9 @@ func (s *fileSystemServer) handleOp(
 	case *fuseops.CreateFileOp:
 		err = s.fs.CreateFile(ctx, typed)
 
+	case *fuseops.CreateLinkOp:
+		err = s.fs.CreateLink(ctx, typed)
+
 	case *fuseops.CreateSymlinkOp:
 		err = s.fs.CreateSymlink(ctx, typed)
 
diff --git a/fuseutil/not_implemented_file_system.go b/fuseutil/not_implemented_file_system.go
index b21e1e3..15cc1a0 100644
--- a/fuseutil/not_implemented_file_system.go
+++ b/fuseutil/not_implemented_file_system.go
@@ -92,6 +92,13 @@ func (fs *NotImplementedFileSystem) CreateSymlink(
 	return
 }
 
+func (fs *NotImplementedFileSystem) CreateLink(
+	ctx context.Context,
+	op *fuseops.CreateLinkOp) (err error) {
+	err = fuse.ENOSYS
+	return
+}
+
 func (fs *NotImplementedFileSystem) Rename(
 	ctx context.Context,
 	op *fuseops.RenameOp) (err error) {