Try to remap keyboard

This can avoid GitHub's key binding control.

Makefile

@@ -1,8 +1,9 @@
 LD=gcc
+LDFLAGS=-lX11
 OBJS=src/main.o
 .PHONY: all
 
 all: xkremap
 
 xkremap: $(OBJS)
-	$(LD) $(OBJS) -o $@
+	$(LD) $(OBJS) $(LDFLAGS) -o $@

src/main.c

@@ -1,8 +1,104 @@
+#include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <X11/Xlib.h>
+#include <X11/keysym.h>
+
+int
+error_handler(Display *display, XErrorEvent *event)
+{
+  // FIXME: log error properly
+  fprintf(stderr, "error detected!\n");
+  return 0;
+}
+
+XKeyEvent
+create_key_event(Display *display, Window window, KeySym keysym, unsigned int modifiers, int type)
+{
+  return (XKeyEvent){
+    .display     = display,
+    .window      = window,
+    .root        = XDefaultRootWindow(display),
+    .subwindow   = None,
+    .time        = CurrentTime,
+    .x           = 1,
+    .y           = 1,
+    .x_root      = 1,
+    .y_root      = 1,
+    .same_screen = True,
+    .keycode     = XKeysymToKeycode(display, keysym),
+    .state       = modifiers,
+    .type        = type,
+  };
+}
+
+void
+input_key(Display *display, KeySym keysym, unsigned int modifiers)
+{
+  Window focus_win;
+  int focus_state;
+  XGetInputFocus(display, &focus_win, &focus_state);
+
+  XKeyEvent event = create_key_event(display, focus_win, keysym, modifiers, KeyPress);
+  XSendEvent(display, focus_win, True, KeyPressMask, (XEvent *)&event);
+
+  event = create_key_event(display, focus_win, keysym, modifiers, KeyRelease);
+  XSendEvent(display, focus_win, True, KeyReleaseMask, (XEvent *)&event);
+}
+
+void
+grab_keys(Display *display)
+{
+  Window root = XDefaultRootWindow(display);
+  XGrabKey(display, XKeysymToKeycode(display, XK_b), ControlMask, root, True, GrabModeAsync, GrabModeAsync);
+}
+
+void
+event_loop(Display *display)
+{
+  XEvent event;
+  while (1) {
+    XNextEvent(display, &event);
+    switch (event.type) {
+      case KeyPress:
+        input_key(display, XK_Left, 0);
+        break;
+      case KeyRelease:
+        // ignore. Is it necessary to handle this?
+        break;
+      case MappingNotify:
+        // FIXME: refresh mapping and grag keys again
+        fprintf(stderr, "mapping notify detected!\n");
+        break;
+      default:
+        fprintf(stderr, "unexpected event detected! (%d)\n", event.type);
+        break;
+    }
+  }
+}
+
+void
+remap_keys()
+{
+  Display *display = XOpenDisplay(NULL);
+  if (!display) {
+    fprintf(stderr, "Failed to open connection with X server!\n");
+    exit(1);
+  }
+
+  XSetErrorHandler(error_handler);
+  XSelectInput(display, XDefaultRootWindow(display), KeyPressMask);
+  grab_keys(display);
+
+  event_loop(display);
+
+  // Close this on atexit?
+  XCloseDisplay(display);
+}
 
 int
 main(int argc, char **argv)
 {
-  printf("Usage: xkremap <config>\n");
+  remap_keys();
   return 0;
 }