1 files changed, 60 insertions, 0 deletions
diff --git a/src/actual.h b/src/actual.h
new file mode 100644
index 0000000..af64ec3
--- /dev/null
+++ b/src/actual.h
@@ -0,0 +1,60 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#ifndef CHANGE_SRC_ACTUAL_FUNCTION_H_
+#define CHANGE_SRC_ACTUAL_FUNCTION_H_
+
+#include <dlfcn.h>
+#include <sys/mman.h>
+#include <sys/uio.h>
+
+#include <memory>
+#include <cstring>
+
+namespace {
+	template <class Result, typename... Arguments>
+	using function_ptr = Result(*)(Arguments...);
+
+	template <typename FunctionPtr>
+	FunctionPtr get_actual_function(const std::string& symbol_name) {
+		const void* symbol_address{ dlsym(RTLD_NEXT, symbol_name.c_str()) };
+
+		FunctionPtr actual_function{};
+		std::memcpy(&actual_function, &symbol_address, sizeof(symbol_address));
+
+		return actual_function;
+	}
+}
+
+namespace actual {
+	static auto write = get_actual_function<
+		function_ptr<ssize_t, int, const void*, size_t>
+	>("write");
+
+	static auto writev = get_actual_function<
+		function_ptr<ssize_t, int, const iovec*, int>
+	>("writev");
+
+	static auto rename = get_actual_function<
+		function_ptr<int, const char*, const char*>
+	>("rename");
+
+	static auto rmdir = get_actual_function<
+		function_ptr<int, const char*>
+	>("rmdir");
+
+	static auto unlink = get_actual_function<
+		function_ptr<int, const char*>
+	>("unlink");
+
+	static auto unlinkat = get_actual_function<
+		function_ptr<int, int, const char*, int>
+	>("unlinkat");
+
+	static auto mmap = get_actual_function<
+		function_ptr<void*, void*, size_t, int, int, int, off_t>
+	>("mmap");
+}
+
+#endif  // CHANGE_SRC_ACTUAL_FUNCTION_H_