making win+space work when no tasks are running

src/kernel/paging.c

@@ -132,7 +132,8 @@ void init_paging() {
 
 __attribute__ ((pure))
 void *vma_to_pma(void *pd, const void *vma) {
-  return (void *)(((uint32_t *)(((uint32_t *)pd)[(uint32_t)vma >> 22] & PE_ADDR_MASK))[((uint32_t)vma >> 12) % 1024] & PE_ADDR_MASK) + (uint32_t)vma % 4096;
+  //this is maybe not good - in the case where pd is zero, vma is returned unconsted. hopefully this doesn't become a problem.
+  return pd ? (void *)(((uint32_t *)(((uint32_t *)pd)[(uint32_t)vma >> 22] & PE_ADDR_MASK))[((uint32_t)vma >> 12) % 1024] & PE_ADDR_MASK) + (uint32_t)vma % 4096 : (void *)(uint32_t)vma;
 }
 
 void switch_to_kernel_cr3() {
@@ -143,6 +144,7 @@ void switch_to_kernel_cr3() {
 }
 
 void switch_to_task_cr3() {
+  if (active_task->page_directory)
     asm volatile (
       "mov %0, %%cr3"
     : : "a" (active_task->page_directory));

src/kernel/task.c

@@ -86,12 +86,12 @@ void advance_active_task() {
 }
 
 void make_sure_tasks() {
+  while (1) {
     for (uint8_t n = 0; n < MAX_TASKS; ++n)
       if (tasks[n].page_directory)
         return;
-  logf(LOG_INFO, "No tasks, halting.");
+    tmp_halt();
-  while (1)
+  }
-    asm("hlt");
 }
 
 //IPC stuff isn't fully implemented, or tested in this version.

src/kernel/window.c

@@ -289,7 +289,6 @@ void on_action(struct window_action packet) {
   if (packet.action_type == NOT_READY)
     return;
 
-  if (top_window) {
   if (packet.action_type == KEY_DOWN)
     for (uint8_t i = 0; i < N_WM_ACTIONS; ++i)
       if (fuzzy_key_match(keybinds[i], packet.as_key)) {
@@ -297,7 +296,7 @@ void on_action(struct window_action packet) {
         struct window *old_top, *old_bottom;
         switch (i) {
         case WM_SHUFFLE_UP:
-            if (!top_window->below)
+          if (!top_window || !top_window->below)
             break;
           old_top = top_window;
           old_bottom = bottom_window;
@@ -310,7 +309,7 @@ void on_action(struct window_action packet) {
           paint_and_above(bottom_window->above);
           break;
         case WM_SHUFFLE_DOWN:
-            if (!top_window->below)
+          if (!top_window || !top_window->below)
             break;
           old_top = top_window;
           old_bottom = bottom_window;
@@ -323,20 +322,28 @@ void on_action(struct window_action packet) {
           paint_and_above(top_window);
           break;
         case WM_MOVE_LEFT:
+          if (top_window) {
             --top_window->xpos;
             paint_all();
+          }
           break;
         case WM_MOVE_RIGHT:
+          if (top_window) {
             ++top_window->xpos;
             paint_all();
+          }
           break;
         case WM_MOVE_UP:
+          if (top_window) {
             --top_window->ypos;
             paint_all();
+          }
           break;
         case WM_MOVE_DOWN:
+          if (top_window) {
             ++top_window->ypos;
             paint_all();
+          }
           break;
         case WM_RUN_COMMAND:
           if (!try_elf_run(drives, run_command, run_command_pass, 0))
@@ -346,6 +353,6 @@ void on_action(struct window_action packet) {
         return;
       }
 
+  if (top_window)
     send_action(top_window, packet);
-  }
 }