vfs: Add resource descriptors

1 files changed, 18 insertions, 0 deletions

diff --git a/src/lib/vfs.zig b/src/lib/vfs.zig
index 798813f..0eb57a6 100644
--- a/src/lib/vfs.zig
+++ b/src/lib/vfs.zig
@@ -15,6 +15,7 @@ pub const Error = error{
     RelativePathNotAllowed,
     NotADirectory,
     NoAbsoluteContainingDirectory,
+    TooManyReferences,
 };
 
 // A stream is a resource that provides a shared data stream with a driver.
@@ -73,6 +74,7 @@ pub const Resource = union(enum) {
 pub const Inode = struct {
     name: []const u8,
     resource: Resource,
+    refs: usize = 0,
 };
 
 pub const Node = std.DoublyLinkedList(Inode).Node;
@@ -112,6 +114,22 @@ pub const Tree = struct {
     }
 };
 
+pub const ResourceDescriptor = struct {
+    inode: *Inode,
+    pos: usize = 0,
+
+    pub fn init(inode: *Inode) !ResourceDescriptor {
+        inode.refs = std.math.add(usize, inode.refs, 1) catch return Error.TooManyReferences;
+        return .{
+            .inode = inode,
+        };
+    }
+
+    pub fn deinit(self: ResourceDescriptor) void {
+        self.inode.refs -|= 1;
+    }
+};
+
 pub fn init(allocator: mem.Allocator) void {
     root = Tree.init(allocator);
 }