hooklib/reg.c: Add registry hook mechanism

hooklib/reg.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <windows.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct reg_hook_val {
+    const wchar_t *name;
+    HRESULT (*read)(void *bytes, uint32_t *nbytes);
+    HRESULT (*write)(const void *bytes, uint32_t nbytes);
+    uint32_t type;
+};
+
+HRESULT reg_hook_push_key(
+        HKEY root,
+        const wchar_t *name,
+        const struct reg_hook_val *vals,
+        size_t nvals);
+
+HRESULT reg_hook_read_bin(
+        void *bytes,
+        uint32_t *nbytes,
+        const void *src_bytes,
+        size_t src_nbytes);
+
+HRESULT reg_hook_read_u32(
+        void *bytes,
+        uint32_t *nbytes,
+        uint32_t src);
+
+HRESULT reg_hook_read_wstr(
+        void *bytes,
+        uint32_t *nbytes,
+        const wchar_t *src);