From f8af0f93d9474e44741d07d9d83aaa6818fd6736 Mon Sep 17 00:00:00 2001
From: chrislu <chris.lu@gmail.com>
Date: Sun, 13 Feb 2022 05:29:43 -0800
Subject: [PATCH] support link

---
 weed/mount/weedfs_link.go | 93 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 weed/mount/weedfs_link.go

diff --git a/weed/mount/weedfs_link.go b/weed/mount/weedfs_link.go
new file mode 100644
index 000000000..c1d634a94
--- /dev/null
+++ b/weed/mount/weedfs_link.go
@@ -0,0 +1,93 @@
+package mount
+
+import (
+	"context"
+	"github.com/chrislusf/seaweedfs/weed/filer"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/hanwen/go-fuse/v2/fuse"
+	"time"
+)
+
+const (
+	HARD_LINK_MARKER = '\x01'
+)
+
+/** Create a hard link to a file */
+func (wfs *WFS) Link(cancel <-chan struct{}, in *fuse.LinkIn, name string, out *fuse.EntryOut) (code fuse.Status) {
+
+	if s := checkName(name); s != fuse.OK {
+		return s
+	}
+
+	newParentPath := wfs.inodeToPath.GetPath(in.NodeId)
+	oldEntryPath := wfs.inodeToPath.GetPath(in.Oldnodeid)
+	oldParentPath, _ := oldEntryPath.DirAndName()
+
+	oldEntry, status := wfs.maybeLoadEntry(oldEntryPath)
+	if status != fuse.OK {
+		return status
+	}
+
+	// update old file to hardlink mode
+	if len(oldEntry.HardLinkId) == 0 {
+		oldEntry.HardLinkId = append(util.RandomBytes(16), HARD_LINK_MARKER)
+		oldEntry.HardLinkCounter = 1
+	}
+	oldEntry.HardLinkCounter++
+	updateOldEntryRequest := &filer_pb.UpdateEntryRequest{
+		Directory:  oldParentPath,
+		Entry:      oldEntry,
+		Signatures: []int32{wfs.signature},
+	}
+
+	// CreateLink 1.2 : update new file to hardlink mode
+	oldEntry.Attributes.Mtime = time.Now().Unix()
+	request := &filer_pb.CreateEntryRequest{
+		Directory: string(newParentPath),
+		Entry: &filer_pb.Entry{
+			Name:            name,
+			IsDirectory:     false,
+			Attributes:      oldEntry.Attributes,
+			Chunks:          oldEntry.Chunks,
+			Extended:        oldEntry.Extended,
+			HardLinkId:      oldEntry.HardLinkId,
+			HardLinkCounter: oldEntry.HardLinkCounter,
+		},
+		Signatures: []int32{wfs.signature},
+	}
+
+	// apply changes to the filer, and also apply to local metaCache
+	err := wfs.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
+
+		wfs.mapPbIdFromLocalToFiler(request.Entry)
+		defer wfs.mapPbIdFromFilerToLocal(request.Entry)
+
+		if err := filer_pb.UpdateEntry(client, updateOldEntryRequest); err != nil {
+			return err
+		}
+		wfs.metaCache.UpdateEntry(context.Background(), filer.FromPbEntry(updateOldEntryRequest.Directory, updateOldEntryRequest.Entry))
+
+		if err := filer_pb.CreateEntry(client, request); err != nil {
+			return err
+		}
+
+		wfs.metaCache.InsertEntry(context.Background(), filer.FromPbEntry(request.Directory, request.Entry))
+
+		return nil
+	})
+
+	newEntryPath := newParentPath.Child(name)
+
+	if err != nil {
+		glog.V(0).Infof("Link %v -> %s: %v", oldEntryPath, newEntryPath, err)
+		return fuse.EIO
+	}
+
+	inode := wfs.inodeToPath.GetInode(newEntryPath)
+
+	wfs.outputPbEntry(out, inode, request.Entry)
+
+	return fuse.OK
+}