vfs: Don't set FileContext.inner initially but provide FileContext.initializer

This allows file providers to know whether an interaction is the first one made with a specific resource descriptor.

2 files changed, 8 insertions, 6 deletions

diff --git a/src/lib/resources.zig b/src/lib/resources.zig
index e02e96c..4a2ae7b 100644
--- a/src/lib/resources.zig
+++ b/src/lib/resources.zig
@@ -348,21 +348,21 @@ fn addDir(path: []const u8) !void {
     });
 }
 
-fn open(context: *vfs.FileContext) !void {
+fn open(context: *vfs.FileContext, initializer: ?*anyopaque) !void {
     const allocator = vfs.treeRoot().allocator;
 
-    const inner = context.inner orelse return Error.NoTarFileInitializer;
-    const old_context: *FileContext = @alignCast(@ptrCast(inner));
+    const init_to = initializer orelse return Error.NoTarFileInitializer;
+    const init_context: *FileContext = @alignCast(@ptrCast(init_to));
 
     const new_context = try allocator.create(FileContext);
-    new_context.* = old_context.*;
+    new_context.* = init_context.*;
 
     context.inner = new_context;
 }
 
 fn read(context: *vfs.FileContext, ptr: [*]u8, len: usize) callconv(.C) Result(usize) {
     if (context.inner == null) {
-        open(context) catch |err| {
+        open(context, context.initializer) catch |err| {
             return Result(usize).fromAnyTypeOrError(err);
         };
     }
diff --git a/src/lib/vfs.zig b/src/lib/vfs.zig
index 951c666..47d631a 100644
--- a/src/lib/vfs.zig
+++ b/src/lib/vfs.zig
@@ -91,6 +91,7 @@ pub const DirHook = extern struct {
 
 pub const FileContext = extern struct {
     inner: ?*anyopaque,
+    initializer: ?*anyopaque,
 };
 
 pub const ResourceKind = enum(u32) {
@@ -185,7 +186,8 @@ pub const ResourceDescriptor = struct {
 
         if (inode.resource.tag == .file) {
             const context = try allocator.create(FileContext);
-            context.inner = inode.resource.data.file.initializer;
+            context.inner = null;
+            context.initializer = inode.resource.data.file.initializer;
 
             return .{
                 .inode = inode,