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kernel/amd64/syscall.c

@@ -27,9 +27,11 @@ uintptr_t syscall_dispatch (void* stack_ptr) {
 
   spin_lock (&thiscpu->lock, &fc);
   struct proc* caller = thiscpu->proc_current;
-  int caller_pid = caller->pid;
+
   spin_lock (&caller->lock, &fp);
 
+  int caller_pid = caller->pid;
+
   memcpy (&caller->pdata.regs, regs, sizeof (struct saved_regs));
 
   fx_save (caller->pdata.fx_env);

kernel/device/device.c

@@ -188,6 +188,7 @@ static void ps2kb_device_init (void) {
 
   device_op_func_t ops[] = {
       [KB_READ_KEY] = &ps2kb_read_key,
+      [KB_READ_KEY_NONBLOCK] = &ps2kb_read_key_nonblock,
   };
   device_create ("kb", ops, lengthof (ops), &ps2kb_init, &ps2kb_fini, NULL, thiscpu->kproc, &rctx);
 }

kernel/device/ps2_kb.c

@@ -213,6 +213,33 @@ DEFINE_DEVICE_OP (ps2kb_read_key) {
   return ST_OK;
 }
 
+DEFINE_DEVICE_OP (ps2kb_read_key_nonblock) {
+  uint64_t frb, fsq;
+
+  uint8_t* chbuf = (uint8_t*)a1;
+
+  if (chbuf == NULL)
+    return -ST_BAD_ADDRESS_SPACE;
+
+  spin_lock (&ps2kb_ringbuffer_lock, &frb);
+
+  size_t prev_count = ps2kb_ringbuffer.count;
+
+  ringbuffer_pop (uint8_t, &ps2kb_ringbuffer, chbuf);
+
+  size_t new_count = ps2kb_ringbuffer.count;
+
+  /* didn't pop anything */
+  if (prev_count == new_count) {
+    spin_unlock (&ps2kb_ringbuffer_lock, frb);
+    return -ST_TRY_AGAIN;
+  }
+
+  spin_unlock (&ps2kb_ringbuffer_lock, frb);
+
+  return ST_OK;
+}
+
 static void ps2kb_set_typematic (uint8_t delay, uint8_t rate) {
   while (inb (KB_CTL_STATUS) & 0x02)
     ;

kernel/device/ps2_kb.h

@@ -11,6 +11,8 @@ struct device;
 
 DEFINE_DEVICE_OP (ps2kb_read_key);
 
+DEFINE_DEVICE_OP (ps2kb_read_key_nonblock);
+
 DEFINE_DEVICE_INIT (ps2kb_init);
 
 DEFINE_DEVICE_FINI (ps2kb_fini);