diff --git a/.gitignore b/.gitignore
index f4f9745..b829a71 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,3 +33,6 @@
 *.app
 
 bin/tests
+default.profraw
+bin/tests.profdata
+bin/tests.profraw
diff --git a/Makefile b/Makefile
index 50b71df..397d6e7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,17 @@
-CXX= clang++
-CXXFLAGS= --std=c++2a
+CXX= clang++-8
+CXXFLAGS= --std=c++17 -fprofile-instr-generate -fcoverage-mapping
 
 all: tests
 
 tests: bin/tests
-	./bin/tests
+	LLVM_PROFILE_FILE="./bin/tests.profraw" ./bin/tests
+	@llvm-profdata merge -sparse ./bin/tests.profraw -o ./bin/tests.profdata
+	@llvm-cov report ./bin/tests -instr-profile=./bin/tests.profdata $(wildcard ./tests/*.cpp) include/*.hpp
+	@llvm-cov report ./bin/tests -instr-profile=./bin/tests.profdata $(wildcard ./tests/*.cpp) include/*.hpp | tail -n 1 | tr -s "\t" | awk '{print "$8" }'
 
-bin/tests: tests.cpp $(wildcard tests/*.cpp)
+bin/tests: tests.cpp $(wildcard tests/*.cpp) ./tests/test_scaffold.h
 	@mkdir -p $(@D)
-	$(CXX) $(CXXFLAGS) -Itests -Iinclude tests.cpp -o $@
\ No newline at end of file
+	$(CXX) $(CXXFLAGS) -Itests -Iinclude tests.cpp -o $@
+
+clean: ./bin
+	@rm -rf $<
\ No newline at end of file
diff --git a/include/shared_fd.hpp b/include/shared_fd.hpp
index 3f59c93..b55f6a3 100644
--- a/include/shared_fd.hpp
+++ b/include/shared_fd.hpp
@@ -1,2 +1,56 @@
 #pragma once
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <string>
 
+namespace gp{
+	using open_opt_flags = int;
+
+	enum class open_options : open_opt_flags {
+		append = O_APPEND,
+		create = O_CREAT,
+		async = O_ASYNC,
+		direct = O_DIRECT,
+		data_sync = O_DSYNC,
+		file_sync = O_SYNC,
+		exclusive = O_EXCL,
+		no_access_time = O_NOATIME,
+		no_follow = O_NOFOLLOW,
+#ifdef O_TEMP
+		temporary = O_TEMP,
+#endif
+#ifdef O_TRUC
+		truncate = O_TRUC,
+#endif
+	};
+
+	using open_opt_mode = int;
+
+	enum class open_modes : open_opt_mode {
+		user_read = S_IRUSR,
+		user_write = S_IWUSR,
+		user_exec = S_IXUSR,
+		group_read = S_IRGRP,
+		group_write = S_IWGRP,
+		group_exec = S_IXGRP,
+		other_read = S_IROTH,
+		other_write = S_IWOTH,
+		other_exec = S_IXOTH,
+		set_uid = S_ISUID,
+		set_gid = S_ISGID,
+		sticky_bit = S_ISVTX,
+	};
+
+	class shared_fd {
+		const int fd;
+		shared_fd(int fd_v)
+		: fd(fd_v) {}
+
+	public:
+		static shared_fd open(const std::string& filename, const open_opt_flags& flags) {
+			
+		}
+	};
+}
\ No newline at end of file
diff --git a/tests.cpp b/tests.cpp
index 91b3af1..b342b0c 100644
--- a/tests.cpp
+++ b/tests.cpp
@@ -1,4 +1,4 @@
-#include "test_scaffold.cpp"
+#include "test_scaffold.h"
 #include "meta_test.cpp"
 #include <iostream>
 
diff --git a/tests/meta_test.cpp b/tests/meta_test.cpp
index a93b928..0c6155d 100644
--- a/tests/meta_test.cpp
+++ b/tests/meta_test.cpp
@@ -1,4 +1,4 @@
-#include "test_scaffold.cpp"
+#include "test_scaffold.h"
 
 struct meta_test : public test_scaffold {
 	meta_test() {
diff --git a/tests/test_scaffold.cpp b/tests/test_scaffold.h
similarity index 100%
rename from tests/test_scaffold.cpp
rename to tests/test_scaffold.h