From 5226853fcafd38975c453c69246743664dc530b1 Mon Sep 17 00:00:00 2001
From: Henrique Dias <mail@hacdias.com>
Date: Sat, 17 May 2025 10:53:07 +0200
Subject: [PATCH] fix: lock files across different users

Fixes #66.
---
 lib/handler.go    | 12 ++++++++++--
 lib/locksystem.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 lib/locksystem.go

diff --git a/lib/handler.go b/lib/handler.go
index 7096518..70ce5f2 100644
--- a/lib/handler.go
+++ b/lib/handler.go
@@ -23,6 +23,8 @@ type Handler struct {
 }
 
 func NewHandler(c *Config) (http.Handler, error) {
+	ls := webdav.NewMemLS()
+
 	h := &Handler{
 		noPassword:  c.NoPassword,
 		behindProxy: c.BehindProxy,
@@ -36,7 +38,10 @@ func NewHandler(c *Config) (http.Handler, error) {
 					Dir:     webdav.Dir(c.Directory),
 					noSniff: c.NoSniff,
 				},
-				LockSystem: webdav.NewMemLS(),
+				LockSystem: &lockSystem{
+					LockSystem: ls,
+					directory:  c.Directory,
+				},
 			},
 		},
 		users: map[string]*handlerUser{},
@@ -51,7 +56,10 @@ func NewHandler(c *Config) (http.Handler, error) {
 					Dir:     webdav.Dir(u.Directory),
 					noSniff: c.NoSniff,
 				},
-				LockSystem: webdav.NewMemLS(),
+				LockSystem: &lockSystem{
+					LockSystem: ls,
+					directory:  u.Directory,
+				},
 			},
 		}
 	}
diff --git a/lib/locksystem.go b/lib/locksystem.go
new file mode 100644
index 0000000..ba41ac2
--- /dev/null
+++ b/lib/locksystem.go
@@ -0,0 +1,35 @@
+package lib
+
+import (
+	"path/filepath"
+	"time"
+
+	"golang.org/x/net/webdav"
+)
+
+var _ webdav.LockSystem = &lockSystem{}
+
+// LockSystem wraps a [webdav.LockSystem] with a root directory, allowing
+// to reuse the same [webdav.LockSystem] for multiple users with different base
+// directories, meaning we can correctly lock the files across different users.
+type lockSystem struct {
+	webdav.LockSystem
+	directory string
+}
+
+func (l *lockSystem) Confirm(now time.Time, name0, name1 string, conditions ...webdav.Condition) (release func(), err error) {
+	if name0 != "" {
+		name0 = filepath.Join(l.directory, name0)
+	}
+
+	if name1 != "" {
+		name1 = filepath.Join(l.directory, name1)
+	}
+
+	return l.LockSystem.Confirm(now, name0, name1, conditions...)
+}
+
+func (l *lockSystem) Create(now time.Time, details webdav.LockDetails) (token string, err error) {
+	details.Root = filepath.Join(l.directory, details.Root)
+	return l.LockSystem.Create(now, details)
+}