Kernel: Make utimensat ignore the dirfd when given an absolute path

Author: https://github.com/implicitfield
Commit: 05cf1327ed
Pull-request: https://github.com/SerenityOS/serenity/pull/23099
Reviewed-by: https://github.com/timschumi ✅

Kernel/Syscalls/utimensat.cpp

@@ -69,8 +69,15 @@ ErrorOr<FlatPtr> Process::sys$utimensat(Userspace<Syscall::SC_utimensat_params c
         times[1] = now;
     }
 
+    auto resolve_base = [&](StringView path) -> ErrorOr<NonnullRefPtr<Custody>> {
+        if (!path.is_empty() && path[0] == '/')
+            return VirtualFileSystem::the().root_custody();
+        else
+            return custody_for_dirfd(params.dirfd);
+    };
+
     auto path = TRY(get_syscall_path_argument(params.path));
-    auto base = TRY(custody_for_dirfd(params.dirfd));
+    auto base = TRY(resolve_base(path->view()));
     auto& atime = times[0];
     auto& mtime = times[1];
     TRY(VirtualFileSystem::the().utimensat(credentials(), path->view(), *base, atime, mtime, follow_symlink));