--- a/src/cx/common.h	Sun May 01 13:14:31 2022 +0200
+++ b/src/cx/common.h	Sun May 01 16:12:13 2022 +0200
@@ -93,6 +93,16 @@
 #include <stddef.h>
 #include <stdbool.h>
 
+/**
+ * Function pointer compatible with fwrite-like functions.
+ */
+typedef size_t (*cx_write_func)(
+        void const *,
+        size_t,
+        size_t,
+        void *
+);
+
 #ifdef _WIN32
 #if !(defined __ssize_t_defined || defined _SSIZE_T_)
 #include <BaseTsd.h>