1 files changed, 35 insertions, 0 deletions
diff --git a/lib/dir_lock.h b/lib/dir_lock.h
new file mode 100644
index 00000000..c9a16c62
--- /dev/null
+++ b/lib/dir_lock.h
@@ -0,0 +1,35 @@
+#ifndef DIR_LOCK_H_INCLUDED
+#define DIR_LOCK_H_INCLUDED
+
+#include <memory>
+#include <zen/file_error.h>
+
+
+struct DirLockCallback //while waiting for the lock
+{
+    virtual ~DirLockCallback() {}
+    virtual void requestUiRefresh() = 0;  //allowed to throw exceptions
+    virtual void reportInfo(const std::wstring& text) = 0;
+};
+
+/*
+RAII structure to place a directory lock against other FFS processes:
+        - recursive locking supported, even with alternate lockfile names, e.g. via symlinks, network mounts etc.
+        - ownership shared between all object instances refering to a specific lock location(= UUID)
+        - can be copied safely and efficiently! (ref-counting)
+        - detects and resolves abandoned locks (instantly if lock is associated with local pc, else after 30 seconds)
+        - temporary locks created during abandoned lock resolution keep "lockfilename"'s extension
+        - race-free (Windows, almost on Linux(NFS))
+*/
+class DirLock
+{
+public:
+    DirLock(const Zstring& lockfilename, DirLockCallback* callback = NULL); //throw FileError, callback only used during construction
+
+private:
+    class LockAdmin;
+    class SharedDirLock;
+    std::shared_ptr<SharedDirLock> sharedLock;
+};
+
+#endif // DIR_LOCK_H_INCLUDED