When a qemu VM crash send the log to the client.

Fix #243

docs/general.rst

@@ -199,3 +199,15 @@ to the nature of the multiple supported VM it's easy for an user to
 upload and run code on your machine.
 
 
+Notifications
+=============
+
+You can receive notification from the server if you listen the HTTP stream /notifications.
+
+The available notification are:
+* ping
+* vm.created
+* vm.started
+* vm.stopped
+* log.error
+

gns3server/modules/qemu/qemu_vm.py

@@ -704,6 +704,7 @@ class QemuVM(BaseVM):
                 self._stdout_file = os.path.join(self.working_dir, "qemu.log")
                 log.info("logging to {}".format(self._stdout_file))
                 with open(self._stdout_file, "w", encoding="utf-8") as fd:
+                    fd.write("Start QEMU with {}\n\nExecution log:\n".format(command_string))
                     self._process = yield from asyncio.create_subprocess_exec(*self._command,
                                                                               stdout=fd,
                                                                               stderr=subprocess.STDOUT,
@@ -732,6 +733,8 @@ class QemuVM(BaseVM):
             log.info("QEMU process has stopped, return code: %d", returncode)
             self.status = "stopped"
             self._process = None
+            if returncode != 0:
+                self.project.emit("log.error", "QEMU process has stopped, return code: {}\n{}".format(returncode, self.read_stdout()))
 
     @asyncio.coroutine
     def stop(self):

tests/modules/qemu/test_qemu_vm.py

@@ -114,6 +114,43 @@ def test_stop(loop, vm, running_subprocess_mock):
         process.terminate.assert_called_with()
 
 
+def test_termination_callback(vm):
+
+    vm.status = "started"
+    queue = vm.project.get_listen_queue()
+
+    vm._termination_callback(0)
+    assert vm.status == "stopped"
+
+    (action, event) = queue.get_nowait()
+    assert action == "vm.stopped"
+    assert event == vm
+
+    with pytest.raises(asyncio.queues.QueueEmpty):
+        queue.get_nowait()
+
+
+def test_termination_callback_error(vm, tmpdir):
+
+    with open(str(tmpdir / "qemu.log"), "w+") as f:
+        f.write("BOOMM")
+
+    vm.status = "started"
+    vm._stdout_file = str(tmpdir / "qemu.log")
+    queue = vm.project.get_listen_queue()
+
+    vm._termination_callback(1)
+    assert vm.status == "stopped"
+
+    (action, event) = queue.get_nowait()
+    assert action == "vm.stopped"
+    assert event == vm
+
+    (action, event) = queue.get_nowait()
+    assert action == "log.error"
+    assert event == "QEMU process has stopped, return code: 1\nBOOMM"
+
+
 def test_reload(loop, vm):
 
     with asyncio_patch("gns3server.modules.qemu.QemuVM._control_vm") as mock: