ios - 代码 "Message from debugger: got unexpected response to k packet: OK"

Question

我在模拟器上测试我的应用程序时收到此消息:

Message from debugger: got unexpected response to k packet: OK

这是什么意思，我的应用是否存在任何危险？

使用 Xcode 6.4 和 7.2

Answer 1

如果您查看文件 ProcessGDBRemote.cpp在 llvm 源代码中，您会看到当 Xcode 的调试器进程出现意外响应时会发生这种情况，在这种情况下，如果数据包不是 'W' 或 'X' 字符:

Error
ProcessGDBRemote::DoDestroy ()
{

    // ...

    if (m_gdb_comm.SendPacketAndWaitForResponse("k", 1, response, send_async) == GDBRemoteCommunication::PacketResult::Success)
    {
        char packet_cmd = response.GetChar(0);

        if (packet_cmd == 'W' || packet_cmd == 'X')
        {
            // ...
        }
        else
        {
            if (log)
            log->Printf ("ProcessGDBRemote::DoDestroy - got unexpected response to k packet: %s", response.GetStringRef().c_str());
            exit_string.assign("got unexpected response to k packet: ");
            exit_string.append(response.GetStringRef());
    }

    // ...

    SetExitStatus(exit_status, exit_string.c_str());

    StopAsyncThread ();
    KillDebugserverProcess ();
    return error;
}

在这种情况下，调试器发送字符串 "OK" 而不是 "W" 或 "X"。您无能为力，Xcode 的幕后存在问题。我发现结合终止 Xcode 的调试进程、重新启动 Xcode 以及在重新连接到调试 session 之前重新启动计算机可以解决此问题。

要了解有关 OS X 上 native 进程的更多信息，请查看嵌套 if 语句中的注释:

// For Native processes on Mac OS X, we launch through the Host Platform, then hand the process off
// to debugserver, which becomes the parent process through "PT_ATTACH".  Then when we go to kill
// the process on Mac OS X we call ptrace(PT_KILL) to kill it, then we call waitpid which returns
// with no error and the correct status.  But amusingly enough that doesn't seem to actually reap
// the process, but instead it is left around as a Zombie.  Probably the kernel is in the process of
// switching ownership back to lldb which was the original parent, and gets confused in the handoff.
// Anyway, so call waitpid here to finally reap it.

关于为什么会出现此错误的有用评论:

// There is a bug in older iOS debugservers where they don't shut down the process
// they are debugging properly.  If the process is sitting at a breakpoint or an exception,
// this can cause problems with restarting.  So we check to see if any of our threads are stopped
// at a breakpoint, and if so we remove all the breakpoints, resume the process, and THEN
// destroy it again.
//
// Note, we don't have a good way to test the version of debugserver, but I happen to know that
// the set of all the iOS debugservers which don't support GetThreadSuffixSupported() and that of
// the debugservers with this bug are equal.  There really should be a better way to test this!
//
// We also use m_destroy_tried_resuming to make sure we only do this once, if we resume and then halt and
// get called here to destroy again and we're still at a breakpoint or exception, then we should
// just do the straight-forward kill.
//
// And of course, if we weren't able to stop the process by the time we get here, it isn't
// necessary (or helpful) to do any of this.