[lldb, lldb-mi] Re-implement MI -exec-continue command.

[polyakov.alex]

Summary

Now -exec-continue command uses SB API to resume target's process.

[clayborg]

So nice to get rid of these HandleCommand hacks!

[polyakov.alex]

Updated because of commited -exec-next and -exec-step commands.

[clayborg]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

An error can claim to fail but not have an error string set. It might be nice to have a helper function that checks to make sure there is an error string on error cases and if there is no error string when error.Success() is false or error.Fail() is true, then set the error string to "unknown error".

[polyakov.alex]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

This functionality might be useful in all lldb-mi commands. So do you know where to place this function? Maybe inside SBError class?

[clayborg]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

I would put it somewhere in lldb-mi in a static function that is something like:

static void SetErrorString(lldb::SBError &error, T &lldbResult) {
  const char *error_cstr = error.GetCString();
  if (error_cstr)
    lldbResult.SetError(error.GetCString());
  else
    lldbResult.SetError("unknown error");
}

Where the T is the type of m_lldbResult.

[clayborg]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

Actually, are we using m_lldbResult now? I didn't realize its type was lldb::SBCommandReturnObject. That was only needed if we were calling:

rSessionInfo.GetDebugger().GetCommandInterpreter().HandleCommand(pCmd, m_lldbResult);

So we can get rid of all "lldb::SBCommandReturnObject m_lldbResult" member variables in any lldb-mi functions where we switch to using the API.

[clayborg]

Also need to remove m_lldbResult from the CMICmdCmdExecContinue class.

tools/lldb-mi/MICmdCmdExec.cpp

234–235

Since we can get rid of m_lldbResult, this should be:

} else return MIstatus::failure;

[polyakov.alex]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

It should be:

else {
  SetError(CMIUtilString::Format(..., error.GetCString()));
  return MIstatus::failure;
}

So, we anyway need a C-style error string.

[labath]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

AFAICT, SBError::GetCString calls Status::AsCString which has a default argument const char *default_error_str = "unknown error". So it sounds like this issue is already taken care of down below. If we are still getting null strings for failed SBErrors, maybe we need to fix something else instead of adding another layer here.

[apolyakov]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

SBError::GetCString potentially may return NULL:

const char *SBError::GetCString() const {
  if (m_opaque_ap.get())
    return m_opaque_ap->AsCString();
  return NULL;
}

[labath]

tools/lldb-mi/MICmdCmdExec.cpp

234–235

Yes, but that can happen only in case SBError::Fail() is false, which means you probably shouldn't be calling GetCString in the first place.

[polyakov.alex]

Removed unnecessary m_lldbResult attribute.

lit/tools/lldb-mi/exec/exec-continue.test

+# RUN: %cc %p/inputs/main.c -g
+# RUN: %lldbmi < %s | FileCheck %s
+
+# Test that lldb-mi can continue executing a program after stop.
+
+-file-exec-and-symbols a.out
+# CHECK: ^done
+
+-break-insert main
+# CHECK: ^done,bkpt={number="1"
+
+-exec-run
+# CHECK: ^running
+# CHECK: *stopped,reason="breakpoint-hit"
+
+-exec-continue
+# CHECK: ^running

lit/tools/lldb-mi/exec/inputs/main.c

+int main(void) {
+  int x = 0;
+  return x;
+}

lit/tools/lldb-mi/exec/lit.local.cfg

+config.suffixes = ['.test']

tools/lldb-mi/MICmdCmdExec.cpp

 //          here.
 // Type:    Overridden.
 // Args:    None.
 // Return:  MIstatus::success - Functional succeeded.
 //          MIstatus::failure - Functional failed.
 // Throws:  None.
 //--
 bool CMICmdCmdExecContinue::Execute() {
-  const char *pCmd = "continue";
-  CMICmnLLDBDebugSessionInfo &rSessionInfo(
-      CMICmnLLDBDebugSessionInfo::Instance());
-  const lldb::ReturnStatus rtn =
-      rSessionInfo.GetDebugger().GetCommandInterpreter().HandleCommand(
-          pCmd, m_lldbResult);
-  MIunused(rtn);
+  lldb::SBError sb_error = 
+      CMICmnLLDBDebugSessionInfo::Instance().GetProcess().Continue();
 
-  if (m_lldbResult.GetErrorSize() == 0) {
+  if (sb_error.Success()) {
     // CODETAG_DEBUG_SESSION_RUNNING_PROG_RECEIVED_SIGINT_PAUSE_PROGRAM
     if (!CMIDriver::Instance().SetDriverStateRunningDebugging()) {
       const CMIUtilString &rErrMsg(CMIDriver::Instance().GetErrorDescription());
       SetError(CMIUtilString::Format(MIRSRC(IDS_CMD_ERR_SET_NEW_DRIVER_STATE),
                                      m_cmdData.strMiCmd.c_str(),
                                      rErrMsg.c_str()));
       return MIstatus::failure;
     }
-  } else {
-    // ToDo: Re-evaluate if this is required when application near finished as
-    // this is parsing LLDB error message
-    // which seems a hack and is code brittle
-    const char *pLldbErr = m_lldbResult.GetError();
-    const CMIUtilString strLldbMsg(CMIUtilString(pLldbErr).StripCREndOfLine());
-    if (strLldbMsg == "error: Process must be launched.") {
-      CMIDriver::Instance().SetExitApplicationFlag(true);
-    }
-  }
+  } else
+    m_lldbResult.SetError(sb_error.GetCString());
 
   return MIstatus::success;
 }
 
 //++
 //------------------------------------------------------------------------------------
 // Details: The invoker requires this function. The command prepares a MI Record
 // Result