vfs: Support providing sub-resources of dirhooks

2 files changed, 24 insertions, 2 deletions

diff --git a/src/lib/sysexchange.zig b/src/lib/sysexchange.zig
index 01220b0..0abf7bc 100644
--- a/src/lib/sysexchange.zig
+++ b/src/lib/sysexchange.zig
@@ -15,6 +15,15 @@ pub const Status = enum(usize) {
             else => .unknown,
         };
     }
+
+    // Calling this on the "success" variant is safety-checked
+    // undefined behavior at runtime.
+    pub fn toError(self: Status) anyerror {
+        return switch (self) {
+            .success => unreachable,
+            .unknown => error.Unknown,
+        };
+    }
 };
 
 pub fn Result(comptime T: type) type {
@@ -46,6 +55,10 @@ pub fn Result(comptime T: type) type {
                 },
             };
         }
+
+        pub fn toErrorUnion(self: Self) !T {
+            return if (self.status == .success) self.value else self.status.toError();
+        }
     };
 }
 
diff --git a/src/lib/vfs.zig b/src/lib/vfs.zig
index 4285b79..3c3099a 100644
--- a/src/lib/vfs.zig
+++ b/src/lib/vfs.zig
@@ -62,7 +62,7 @@ pub const DirHook = extern struct {
     findFn: FindFn,
     removeFn: RemoveFn,
 
-    pub const ProvideFn = *allowzero const fn (inode: Inode) callconv(.C) sysexchange.Result(void);
+    pub const ProvideFn = *allowzero const fn (name_ptr: [*]const u8, name_len: usize, inode: Inode) callconv(.C) sysexchange.Result(void);
     pub const FindFn = *allowzero const fn (name_ptr: [*]const u8, name_len: usize) callconv(.C) ?*Inode;
     pub const RemoveFn = *allowzero const fn (name_ptr: [*]const u8, name_len: usize) callconv(.C) sysexchange.Result(void);
 };
@@ -252,18 +252,27 @@ pub fn provideResource(path: []const u8, resource: Resource, pid: u16) !void {
 
     const dirname = std.fs.path.dirnamePosix(path) orelse return Error.NoAbsoluteContainingDirectory;
     if (find(dirname)) |inode| {
+        const basename = std.fs.path.basenamePosix(path);
         return switch (inode.resource.tag) {
             .dir => blk: {
                 const dir = inode.resource.data.dir;
 
                 break :blk dir.provideResource(.{
-                    .name = std.fs.path.basenamePosix(path),
+                    .name = basename,
                     .inode = .{
                         .resource = resource,
                         .pid = pid,
                     },
                 });
             },
+            .dir_hook => blk: {
+                const dir_hook = inode.resource.data.dir_hook;
+
+                break :blk dir_hook.provideFn(basename.ptr, basename.len, .{
+                    .resource = resource,
+                    .pid = pid,
+                }).toErrorUnion();
+            },
             else => Error.NotADirectory,
         };
     } else return Error.NotFound;