diff --git a/all.h b/all.h
index ea83e5e..787c9c9 100644
--- a/all.h
+++ b/all.h
@@ -288,6 +288,11 @@ typedef u32 b32;
 #define false 0
 
 // Structs
+typedef struct Resulti64 {
+  bool success;
+  i64 value;
+} Resulti64;
+
 typedef struct Arena {
   u8* memory;
   u64 max;
@@ -462,6 +467,7 @@ union Range1f32
 
   int poll(struct pollfd *fds, nfds_t nfds, int timeout);
 #else
+#  include <signal.h>
 #  include <poll.h>
 #  include <sys/socket.h>
 #  include <netinet/in.h>
@@ -598,6 +604,7 @@ fn bool isSimplePrintable(u8 c);
 
 ///// OS-wrapped apis
 void      osInit();
+void      osSetCtrlCCallback(void (*handler)());
 void*     osThreadContextGet();
 void      osThreadContextSet(void* ctx);
 bool      osThreadJoin(Thread handle, u64 endt_us);
@@ -620,6 +627,9 @@ fn String osFileRead(Arena* arena, ptr filepath);
 fn bool   osFileCreate(String filename);
 fn bool   osFileCreateWrite(String filename, String data);
 fn bool   osFileWrite(String filename, String data);
+fn Resulti64 osFileOpenForWriting(String filename);
+fn Resulti64 osFileClose(Resulti64 handle);
+fn bool   osFileWriteOpenFile(Resulti64 handle, String data);
 
 fn void   osDebugPrint(bool debug_mode, const char* format, ...);
 
diff --git a/mac_os.c b/mac_os.c
index ede0437..f8c294e 100644
--- a/mac_os.c
+++ b/mac_os.c
@@ -124,6 +124,33 @@ fn bool osFileWrite(String filename, String data) {
   return result;
 }
 
+fn Resulti64 osFileOpenForWriting(String filename) {
+  size_t handle = open((str)filename.bytes, O_WRONLY | O_APPEND, S_IRUSR | S_IRGRP | S_IROTH);
+  Resulti64 result = {
+    .success = handle != -1,
+    .value = (i64)handle,
+  };
+  return result;
+}
+
+fn Resulti64 osFileClose(Resulti64 handle) {
+  i32 close_result = close((size_t)handle.value);
+  Resulti64 result = {
+    .success = close_result != -1,
+    .value = (i64)close_result,
+  };
+  return result;
+}
+
+fn bool osFileWriteOpenFile(Resulti64 handle, String data) {
+  assert(handle.success == true);
+  i32 wrote_this_round = 0;
+  for (i32 bytes_written = 0; bytes_written < data.length; bytes_written += wrote_this_round) {
+    wrote_this_round = write((size_t)handle.value, data.bytes + bytes_written, data.length - bytes_written);
+    if (wrote_this_round == -1) return false;
+  }
+  return true;
+}
 
 // Misc
 fn void osDebugPrint(bool debug_mode, const char * format, ... ) {
diff --git a/unix_os.c b/unix_os.c
index c39c96f..ad6b599 100644
--- a/unix_os.c
+++ b/unix_os.c
@@ -1,11 +1,23 @@
 #include "all.h"
 
 global pthread_key_t linux_thread_context_key;
+global void (*_ctrl_c_handler_fn_ptr)() = NULL;
 // ThreadContext
 void osInit() {
   pthread_key_create(&linux_thread_context_key, NULL);
 }
 
+void _osGenericSignalHandler(i32 signal) {
+  if (signal == SIGINT && _ctrl_c_handler_fn_ptr != NULL) {
+    _ctrl_c_handler_fn_ptr();
+  }
+}
+
+void osSetCtrlCCallback(void (*handler)()) {
+  _ctrl_c_handler_fn_ptr = handler;
+  signal(SIGINT, _osGenericSignalHandler);
+}
+
 void* osThreadContextGet() {
   return pthread_getspecific(linux_thread_context_key);
 }
diff --git a/win32_os.c b/win32_os.c
index 4f1b061..5713792 100644
--- a/win32_os.c
+++ b/win32_os.c
@@ -5,6 +5,7 @@
 
 static u64 w32_ticks_per_sec = 1;
 static u32 w32_thread_context_index;
+global void (*_ctrl_c_handler_fn_ptr)() = NULL;
 
 void osInit() {
 	LARGE_INTEGER perf_freq = {0};
@@ -16,6 +17,19 @@ void osInit() {
 	w32_thread_context_index = TlsAlloc();
 }
 
+BOOL WINAPI _osGenericSignalHandler(DWORD event) {
+  if (event == CTRL_C_EVENT && _ctrl_c_handler_fn_ptr != NULL) {
+    _ctrl_c_handler_fn_ptr();
+    return TRUE;
+  }
+  return FALSE;
+}
+
+void osSetCtrlCCallback(void (*handler)()) {
+  _ctrl_c_handler_fn_ptr = handler;
+  SetConsoleCtrlHandler(_osGenericSignalHandler, TRUE);
+}
+
 void* osThreadContextGet() {
 	return TlsGetValue(w32_thread_context_index);
 }
@@ -90,6 +104,21 @@ fn bool osFileWrite(String filename, String data) {
   return result;
 }
 
+fn Resulti64 osFileOpenForWriting(String filename) {
+  assert(false && "Not Implemented");
+  return (Resulti64) {};
+}
+
+fn Resulti64 osFileClose(Resulti64 handle) {
+  assert(false && "Not Implemented");
+  return (Resulti64) {};
+}
+
+fn bool osFileWriteOpenFile(Resulti64 handle, String data) {
+  assert(false && "Not Implemented");
+  return false;
+}
+
 
 // Misc
 fn void osDebugPrint(bool debug_mode, const char * format, ... ) {