Add symlink support to mount command for rclone#2975

cmd/mount/dir.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strings"
 	"syscall"
 	"time"
 
@@ -75,7 +76,13 @@ func (d *Dir) Lookup(ctx context.Context, req *fuse.LookupRequest, resp *fuse.Lo
 	defer log.Trace(d, "name=%q", req.Name)("node=%+v, err=%v", &node, &err)
 	mnode, err := d.Dir.Stat(req.Name)
 	if err != nil {
-		return nil, translateError(err)
+		// might be a symlink; so check to see if it is
+		symlink_mnode, err := d.Dir.Stat(req.Name + ".rclonelink")
+		if err != nil {
+			return nil, translateError(err)
+		}
+		// symlink found
+		mnode = symlink_mnode
 	}
 	resp.EntryValid = time.Duration(d.fsys.opt.AttrTimeout)
 	// Check the mnode to see if it has a fuse Node cached
@@ -128,6 +135,11 @@ func (d *Dir) ReadDirAll(ctx context.Context) (dirents []fuse.Dirent, err error)
 		}
 		if node.IsDir() {
 			dirent.Type = fuse.DT_Dir
+		} else if strings.HasSuffix(name, ".rclonelink") {
+			// node represents a symlink; mark it as such, and remove the suffix from the node name
+			dirent.Type = fuse.DT_Link
+			dirent.Name = name[:len(name)-len(".rclonelink")]
+			defer log.Trace(d, name + " is a symlink; new name is " + dirent.Name)(name + " is a symlink; new name is " + dirent.Name, &itemsRead, &err)
 		}
 		dirents = append(dirents, dirent)
 	}
@@ -174,6 +186,17 @@ var _ fusefs.NodeRemover = (*Dir)(nil)
 // may correspond to a file (unlink) or to a directory (rmdir).
 func (d *Dir) Remove(ctx context.Context, req *fuse.RemoveRequest) (err error) {
 	defer log.Trace(d, "name=%q", req.Name)("err=%v", &err)
+
+	_, err = d.Dir.Stat(req.Name)
+	if err != nil && err == vfs.ENOENT {
+		// check for removing symlink
+		err = d.Dir.RemoveName(req.Name + ".rclonelink")
+		if err != nil {
+			return translateError(err)
+		}
+		return nil
+	}
+
 	err = d.Dir.RemoveName(req.Name)
 	if err != nil {
 		return translateError(err)
@@ -201,6 +224,17 @@ func (d *Dir) Rename(ctx context.Context, req *fuse.RenameRequest, newDir fusefs
 		return fmt.Errorf("unknown Dir type %T", newDir)
 	}
 
+	_, err = d.Dir.Stat(req.OldName)
+	// if the file cannot be found, it might be because it is a symbolic link
+	if err != nil && err == vfs.ENOENT {
+		defer log.Trace(d, "Could not find file " + req.OldName + "; checking for symbolic link")("err=%v", &err)
+		err = d.Dir.Rename(req.OldName + ".rclonelink", req.NewName + ".rclonelink", destDir.Dir)
+		if err != nil {
+			return translateError(err)
+		}
+		return nil
+	}
+
 	err = d.Dir.Rename(req.OldName, req.NewName, destDir.Dir)
 	if err != nil {
 		return translateError(err)
@@ -268,3 +302,37 @@ func (d *Dir) Mknod(ctx context.Context, req *fuse.MknodRequest) (node fusefs.No
 	}
 	return node, nil
 }
+
+var _ fusefs.NodeSymlinker = (*Dir)(nil)
+
+// create symbolic link
+func (d *Dir) Symlink(ctx context.Context, req *fuse.SymlinkRequest) (node fusefs.Node, err error) {
+	defer log.Trace(d, "target=%q; new_name=%q", req.Target, req.NewName)("node=%v, err=%v", &node, &err)
+
+	symlinkName := req.NewName + ".rclonelink"
+	file, err := d.Dir.Create(symlinkName, os.O_RDWR)
+	if err != nil {
+		defer log.Trace(d, "failed to create symlink file " + symlinkName)
+		return nil, translateError(err)
+	}
+	fh, err := file.Open(os.O_RDWR | os.O_CREATE)
+	if err != nil {
+		defer log.Trace(d, "failed to open symlink file " + symlinkName)
+		return nil, translateError(err)
+	}
+	node = &File{file, d.fsys}
+
+	_, err2 := fh.WriteAt([]byte(req.Target), 0)
+	if err2 != nil {
+		defer log.Trace(d, "failed to write to symlink file " + symlinkName)
+		return nil, translateError(err2)
+	}
+
+	err = fh.Release()
+	if err != nil {
+		defer log.Trace(d, "failed to close symlink file " + symlinkName)
+		return nil, translateError(err)
+	}
+
+	return node, err
+}

cmd/mount/file.go

@@ -4,7 +4,9 @@ package mount
 
 import (
 	"context"
+	"io"
 	"os"
+	"strings"
 	"syscall"
 	"time"
 
@@ -33,6 +35,10 @@ func (f *File) Attr(ctx context.Context, a *fuse.Attr) (err error) {
 	a.Gid = f.VFS().Opt.GID
 	a.Uid = f.VFS().Opt.UID
 	a.Mode = os.FileMode(f.VFS().Opt.FilePerms)
+	if strings.HasSuffix(f.File.Name(), ".rclonelink") {
+		defer log.Trace(f, f.File.Name()+" is a symlink")("a=%+v, err=%v", a, &err)
+		a.Mode = 0777 | os.ModeSymlink
+	}
 	a.Size = Size
 	a.Atime = modTime
 	a.Mtime = modTime
@@ -129,3 +135,24 @@ func (f *File) Removexattr(ctx context.Context, req *fuse.RemovexattrRequest) er
 }
 
 var _ fusefs.NodeRemovexattrer = (*File)(nil)
+
+var _ fusefs.NodeReadlinker = (*File)(nil)
+
+// read symbolic link target
+func (f *File) Readlink(ctx context.Context, req *fuse.ReadlinkRequest) (ret string, err error) {
+	defer log.Trace(f, "Requested to read link")("ret=%v, err=%v", &ret, &err)
+
+	handle, err := f.File.Open(syscall.O_RDONLY)
+	if err != nil {
+		return "", translateError(err)
+	}
+	data := make([]byte, f.File.Size())
+	_, err = handle.Read(data)
+	if err == io.EOF {
+		err = nil
+	} else if err != nil {
+		return "", translateError(err)
+	}
+
+	return string(data), nil
+}