WalkHandler: pass Directory& to OnWalkAncient()

We need to be able to take a reference (for asynchronous io_uring
calls).

src/Cull.cxx

@@ -98,10 +98,10 @@ Cull::Start(FileDescriptor root_fd)
 }
 
 void
-Cull::OnWalkAncient(FileDescriptor directory_fd,
+Cull::OnWalkAncient(WalkDirectory &directory,
 		    std::string_view filename) noexcept
 {
-	CullFile(dev_cachefiles, directory_fd, filename);
+	CullFile(dev_cachefiles, directory.fd, filename);
 }
 
 void

src/Cull.hxx

@@ -56,7 +56,7 @@ private:
 	void Finish() noexcept;
 
 	// virtual methods from WalkHandler
-	void OnWalkAncient(FileDescriptor directory_fd,
+	void OnWalkAncient(WalkDirectory &directory,
 			   std::string_view filename) noexcept override;
 	void OnWalkFinished(WalkResult &&result) noexcept override;
 };

src/WHandler.hxx

@@ -7,6 +7,7 @@
 #include <string_view>
 
 class FileDescriptor;
+struct WalkDirectory;
 struct WalkResult;
 
 /**
@@ -18,7 +19,7 @@ public:
 	 * An "ancient" file was found (that should be culled
          * unconditionally).
 	 */
-	virtual void OnWalkAncient(FileDescriptor directory_fd,
+	virtual void OnWalkAncient(WalkDirectory &directory,
 				   std::string_view filename) noexcept = 0;
 
 	/**

src/Walk.cxx

@@ -110,7 +110,7 @@ Walk::AddFile(WalkDirectory &parent, std::string &&name,
 	      FileTime atime, uint_least64_t size)
 {
 	if (atime < discard_older_than) {
-		handler.OnWalkAncient(parent.fd, name);
+		handler.OnWalkAncient(parent, name);
 		return;
 	}
 

test/RunWalk.cxx

@@ -37,7 +37,7 @@ struct Instance final : WalkHandler {
 	}
 
 	// virtual methods from WalkHandler
-	void OnWalkAncient([[maybe_unused]] FileDescriptor directory_fd,
+	void OnWalkAncient([[maybe_unused]] WalkDirectory &directory,
 			   std::string_view filename) noexcept override {
 		fmt::print("ancient {:?}\n", filename);
 	}