Add UnpackingNode::IsOnlyPackageNode()

It returns whether the given package node is the only package node
attached to that node.

src/add-ons/kernel/file_systems/packagefs/UnpackingDirectory.cpp

@@ -132,6 +132,14 @@ UnpackingDirectory::GetPackageNode()
 }
 
 
+bool
+UnpackingDirectory::IsOnlyPackageNode(PackageNode* node) const
+{
+	return node == fPackageDirectories.Head()
+		&& node == fPackageDirectories.Tail();
+}
+
+
 status_t
 UnpackingDirectory::OpenAttributeDirectory(AttributeDirectoryCookie*& _cookie)
 {

src/add-ons/kernel/file_systems/packagefs/UnpackingDirectory.h

@@ -28,6 +28,7 @@ public:
 	virtual	void				RemovePackageNode(PackageNode* packageNode);
 
 	virtual	PackageNode*		GetPackageNode();
+	virtual	bool				IsOnlyPackageNode(PackageNode* node) const;
 
 	virtual	status_t			OpenAttributeDirectory(
 									AttributeDirectoryCookie*& _cookie);

src/add-ons/kernel/file_systems/packagefs/UnpackingLeafNode.cpp

@@ -156,6 +156,14 @@ UnpackingLeafNode::GetPackageNode()
 }
 
 
+bool
+UnpackingLeafNode::IsOnlyPackageNode(PackageNode* node) const
+{
+	PackageLeafNode* head = fPackageNodes.Head();
+	return node == head && fPackageNodes.GetNext(head) == NULL;
+}
+
+
 status_t
 UnpackingLeafNode::Read(off_t offset, void* buffer, size_t* bufferSize)
 {

src/add-ons/kernel/file_systems/packagefs/UnpackingLeafNode.h

@@ -31,6 +31,7 @@ public:
 	virtual	void				RemovePackageNode(PackageNode* packageNode);
 
 	virtual	PackageNode*		GetPackageNode();
+	virtual	bool				IsOnlyPackageNode(PackageNode* node) const;
 
 	virtual	status_t			Read(off_t offset, void* buffer,
 									size_t* bufferSize);

src/add-ons/kernel/file_systems/packagefs/UnpackingNode.h

@@ -23,6 +23,7 @@ public:
 	virtual	void				RemovePackageNode(PackageNode* packageNode) = 0;
 
 	virtual	PackageNode*		GetPackageNode() = 0;
+	virtual	bool				IsOnlyPackageNode(PackageNode* node) const = 0;
 };