debugger stop button on Linux console pgm crashes CB

[Pecan]

When debugging a linux console program, and I hit the red stop button, CB crashes as follows:

Code Select Expand


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1230633296 (LWP 2568)]
0xb46a4fe4 in DebuggerDriver::CurrentCommand (this=0x8cde9e8)
    at plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) bt
#0  0xb46a4fe4 in DebuggerDriver::CurrentCommand (this=0x8cde9e8)
    at plugins/debuggergdb/debuggerdriver.cpp:98
#1  0xb46caa31 in GDB_driver::ParseOutput (this=0x8cde9e8, output=@0xbfc9063c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
#2  0xb46a8811 in DebuggerGDB::ParseOutput (this=0x8a17b90, output=@0xbfc9063c)
    at plugins/debuggergdb/debuggergdb.cpp:1543
#3  0xb46aac39 in DebuggerGDB::OnGDBOutput (this=0x8a17b90, event=@0x8a2ae40)
    at plugins/debuggergdb/debuggergdb.cpp:1916
#4  0xb7991655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#5  0xb7a20b52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#6  0xb7a20c9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#7  0xb7a20e1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#8  0xb7a212d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#9  0xb7991bef in wxAppConsole::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#10 0xb776e4dd in Manager::ProcessPendingEvents () at sdk/manager.cpp:108
#11 0xb782d4cf in SimpleTextLog::AddLog (this=0x8b25b58, msg=@0xbfc909cc,
    addNewLine=true) at sdk/simpletextlog.cpp:70
---Type <return> to continue, or q <return> to quit---q
Quit
(gdb) f
#0  0xb46a4fe4 in DebuggerDriver::CurrentCommand (this=0x8cde9e8)
    at plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) p m_DCmds
$16 = {<wxBaseArrayPtrVoid> = {m_nSize = 21, m_nCount = 22,
    m_pItems = 0x17}, <No data fields>}
(gdb) Quit
(gdb)



[artoj]

Most likely this one: Bug #10077 DebuggerDriver crashes CB <<- Stop Debugger, close App

I also got a backtrace (the one in my comment).

[Pecan]

Most likely this one: Bug #10077 DebuggerDriver crashes CB <<- Stop Debugger, close App

I also got a backtrace (the one in my comment).

Thanks, I'll add my backtrace to it and so something about it as soon as I get the Linux console patch in.

[Pecan]

While I was trying to chase the stop button crash down, I got another type of crash.
Note that m_Cursor has an invalid address. (So did m_DCmds)

Code Select Expand


(gdb) p m_DCmds
$16 = {<wxBaseArrayPtrVoid> = {m_nSize = 21, m_nCount = 22,
    m_pItems = 0x17}, <No data fields>}
(gdb) Quit
(gdb)

Both crashes are symptomatic in that these are class variables, not heap, and they both reside in debuggerdriver.h

I dont understand how they could be invalid since debuggerdriver doesn't appear to be a dynamic class. At least I haven't found a "new debuggerdriver(...)" statement yet.

Code Select Expand


// third type of crash
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1231137104 (LWP 1536)]
0xb796b144 in wxStringBase::operator= () from /usr/lib/libwx_baseu-2.6.so.0
(gdb) bt
#0  0xb796b144 in wxStringBase::operator= () from /usr/lib/libwx_baseu-2.6.so.0
#1  0x08073dda in wxString::operator= (this=0x8fc8cf8)
    at /usr/include/wx-2.6/wx/string.h:611
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
#3  0xb4650a28 in GDB_driver::ParseOutput (this=0x8fc8cd0, output=@0xbfa8850c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:811
#4  0xb462d84d in DebuggerGDB::ParseOutput (this=0x89da6f8, output=@0xbfa8850c)
    at plugins/debuggergdb/debuggergdb.cpp:1543
#5  0xb462fc75 in DebuggerGDB::OnGDBOutput (this=0x89da6f8, event=@0x89eb74c)
    at plugins/debuggergdb/debuggergdb.cpp:1916
#6  0xb7916655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#7  0xb79a5b52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#8  0xb79a5c9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#9  0xb79a5e1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#10 0xb79a62d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#11 0xb7916bef in wxAppConsole::ProcessPendingEvents ()
---Type <return> to continue, or q <return> to quit---q
from /usr/lib/libwx_baseQuit
(gdb) f 2
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
885                     m_Cursor.file = reBreak.GetMatch( line, 1);
(gdb) p line
$1 = (wxString &) @0xbfa8846c: {<wxStringBase> = {static npos = 4294967295,
    m_pchData = 0x902ea0c}, <No data fields>}
(gdb) x/s10 line.m_pchData
A syntax error in expression, near `line.m_pchData'.
(gdb) x/10s  line.m_pchData
0x902ea0c:       "\032"
0x902ea0e:       ""
0x902ea0f:       ""
0x902ea10:       "\032"
0x902ea12:       ""
0x902ea13:       ""
0x902ea14:       "/"
0x902ea16:       ""
0x902ea17:       ""
0x902ea18:       "h"
(gdb) x/20s  line.m_pchData
0x902ea0c:       "\032"
0x902ea0e:       ""
0x902ea0f:       ""
0x902ea10:       "\032"
0x902ea12:       ""
0x902ea13:       ""
0x902ea14:       "/"
0x902ea16:       ""
0x902ea17:       ""
0x902ea18:       "h"
0x902ea1a:       ""
0x902ea1b:       ""
0x902ea1c:       "o"
0x902ea1e:       ""
0x902ea1f:       ""
0x902ea20:       "m"
0x902ea22:       ""
0x902ea23:       ""
0x902ea24:       "e"
0x902ea26:       ""
(gdb) x/20c  line.m_pchData
0x902ea0c:      26 '\032'       0 '\0'  0 '\0'  0 '\0'  26 '\032'       0 '\0' 0 '\0'   0 '\0'
0x902ea14:      47 '/'  0 '\0'  0 '\0'  0 '\0'  104 'h' 0 '\0'  0 '\0'  0 '\0'
0x902ea1c:      111 'o' 0 '\0'  0 '\0'  0 '\0'
(gdb) f
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
885                     m_Cursor.file = reBreak.GetMatch( line, 1);
(gdb) p m_Cursor
$2 = {file = {<wxStringBase> = {static npos = 4294967295,
      m_pchData = 0x75}, <No data fields>}, address = {<wxStringBase> = {
      static npos = 4294967295, m_pchData = 0x67}, <No data fields>},
  function = {<wxStringBase> = {static npos = 4294967295,
      m_pchData = 0x67}, <No data fields>}, line = 105, changed = 110}
(gdb)

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1231137104 (LWP 1536)]
0xb796b144 in wxStringBase::operator= () from /usr/lib/libwx_baseu-2.6.so.0
(gdb) bt
#0  0xb796b144 in wxStringBase::operator= () from /usr/lib/libwx_baseu-2.6.so.0
#1  0x08073dda in wxString::operator= (this=0x8fc8cf8)
    at /usr/include/wx-2.6/wx/string.h:611
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
#3  0xb4650a28 in GDB_driver::ParseOutput (this=0x8fc8cd0, output=@0xbfa8850c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:811
#4  0xb462d84d in DebuggerGDB::ParseOutput (this=0x89da6f8, output=@0xbfa8850c)
    at plugins/debuggergdb/debuggergdb.cpp:1543
#5  0xb462fc75 in DebuggerGDB::OnGDBOutput (this=0x89da6f8, event=@0x89eb74c)
    at plugins/debuggergdb/debuggergdb.cpp:1916
#6  0xb7916655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#7  0xb79a5b52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#8  0xb79a5c9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#9  0xb79a5e1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#10 0xb79a62d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#11 0xb7916bef in wxAppConsole::ProcessPendingEvents ()
---Type <return> to continue, or q <return> to quit---q
from /usr/lib/libwx_baseQuit
(gdb) f 2
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
885                     m_Cursor.file = reBreak.GetMatch( line, 1);
(gdb) p line
$1 = (wxString &) @0xbfa8846c: {<wxStringBase> = {static npos = 4294967295,
    m_pchData = 0x902ea0c}, <No data fields>}
(gdb) x/s10 line.m_pchData
A syntax error in expression, near `line.m_pchData'.
(gdb) x/10s  line.m_pchData
0x902ea0c:       "\032"
0x902ea0e:       ""
0x902ea0f:       ""
0x902ea10:       "\032"
0x902ea12:       ""
0x902ea13:       ""
0x902ea14:       "/"
0x902ea16:       ""
0x902ea17:       ""
0x902ea18:       "h"
(gdb) x/20s  line.m_pchData
0x902ea0c:       "\032"
0x902ea0e:       ""
0x902ea0f:       ""
0x902ea10:       "\032"
0x902ea12:       ""
0x902ea13:       ""
0x902ea14:       "/"
0x902ea16:       ""
0x902ea17:       ""
0x902ea18:       "h"
0x902ea1a:       ""
0x902ea1b:       ""
0x902ea1c:       "o"
0x902ea1e:       ""
0x902ea1f:       ""
0x902ea20:       "m"
0x902ea22:       ""
0x902ea23:       ""
0x902ea24:       "e"
0x902ea26:       ""
(gdb) x/20c  line.m_pchData
0x902ea0c:      26 '\032'       0 '\0'  0 '\0'  0 '\0'  26 '\032'       0 '\0' 0 '\0'   0 '\0'
0x902ea14:      47 '/'  0 '\0'  0 '\0'  0 '\0'  104 'h' 0 '\0'  0 '\0'  0 '\0'
0x902ea1c:      111 'o' 0 '\0'  0 '\0'  0 '\0'
(gdb) f
#2  0xb464e9f5 in GDB_driver::HandleMainBreakPoint (this=0x8fc8cd0,
    reBreak=@0xb467f998, line=@0xbfa8846c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:885
885                     m_Cursor.file = reBreak.GetMatch( line, 1);
(gdb) p m_Cursor
$2 = {file = {<wxStringBase> = {static npos = 4294967295,
      m_pchData = 0x75}, <No data fields>}, address = {<wxStringBase> = {
      static npos = 4294967295, m_pchData = 0x67}, <No data fields>},
  function = {<wxStringBase> = {static npos = 4294967295,
      m_pchData = 0x67}, <No data fields>}, line = 105, changed = 110}
(gdb)

(gdb) p m_Cursor.file
$3 = {<wxStringBase> = {static npos = 4294967295,
    m_pchData = 0x75}, <No data fields>}
(gdb) Quit
(gdb)




Edit: Looks like both got to GDB_driver::ParseOutput by way of
DebuggerGDB::ParseOutput which depends on m_State.GetDrive()

Code Select Expand


void DebuggerGDB::ParseOutput(const wxString& output)
{
    if (m_State.HasDriver())
    {
        m_State.GetDriver()->ParseOutput(output);
    }
}



My guess is that somehow, GetDriver is returning an incorrect addr.

[Pecan]

Looks like m_State.m_pDriver is 0x0 when ParseOutput is called.

Code Select Expand


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1230625104 (LWP 2242)]
0xb46a7020 in DebuggerDriver::CurrentCommand (this=0x914f728)
    at plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) bt
#0  0xb46a7020 in DebuggerDriver::CurrentCommand (this=0x914f728)
    at plugins/debuggergdb/debuggerdriver.cpp:98
#1  0xb46ccb07 in GDB_driver::ParseOutput (this=0x914f728, output=@0xbfcdc3cc)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
#2  0xb46aa84d in DebuggerGDB::ParseOutput (this=0x8a17bc8, output=@0xbfcdc3cc)
    at plugins/debuggergdb/debuggergdb.cpp:1543
#3  0xb46acc75 in DebuggerGDB::OnGDBOutput (this=0x8a17bc8, event=@0xb3c005c4)
    at plugins/debuggergdb/debuggergdb.cpp:1916
#4  0xb7993655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#5  0xb7a22b52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#6  0xb7a22c9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#7  0xb7a22e1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#8  0xb7a232d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#9  0xb7993bef in wxAppConsole::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#10 0xb77704dd in Manager::ProcessPendingEvents () at sdk/manager.cpp:108
#11 0xb782f4cf in SimpleTextLog::AddLog (this=0x8b24788, msg=@0xbfcdc75c,
    addNewLine=true) at sdk/simpletextlog.cpp:70
#12 0xb7775001 in MessageManager::Log (this=0x860acc0, id=6, msg=@0xbfcdc75c)
    at sdk/messagemanager.cpp:455
#13 0xb46a7f8a in DebuggerGDB::DebugLog (this=0x8a17bc8, msg=@0xbfcdc75c)
    at plugins/debuggergdb/debuggergdb.cpp:566
#14 0xb46ccac9 in GDB_driver::ParseOutput (this=0x914f728, output=@0xbfcdc75c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:613
#15 0xb46aa84d in DebuggerGDB::ParseOutput (this=0x8a17bc8, output=@0xbfcdc75c)
    at plugins/debuggergdb/debuggergdb.cpp:1543
#16 0xb46acc75 in DebuggerGDB::OnGDBOutput (this=0x8a17bc8, event=@0xb3c00474)
    at plugins/debuggergdb/debuggergdb.cpp:1916
#17 0xb7993655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#18 0xb7a22b52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#19 0xb7a22c9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#20 0xb7a22e1f in wxEvtHandler::ProcessEvent ()
---Type <return> to continue, or q <return> to quit---q
from /usr/lib/libwx_baseu-2.6.soQuit
(gdb) f
#0  0xb46a7020 in DebuggerDriver::CurrentCommand (this=0x914f728)
    at plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) p m_DCmds
$1 = {<wxBaseArrayPtrVoid> = {m_nSize = 16, m_nCount = 1,
    m_pItems = 0x0}, <No data fields>}
(gdb) p m_DCmds[0]
$2 = (_wxArrayDebuggerCommands &) @0x0: Cannot access memory at address 0x0
(gdb) f 2
#2  0xb46aa84d in DebuggerGDB::ParseOutput (this=0x8a17bc8, output=@0xbfcdc3cc)
    at plugins/debuggergdb/debuggergdb.cpp:1543
1543            m_State.GetDriver()->ParseOutput(output);
(gdb) f
#2  0xb46aa84d in DebuggerGDB::ParseOutput (this=0x8a17bc8, output=@0xbfcdc3cc)
    at plugins/debuggergdb/debuggergdb.cpp:1543
1543            m_State.GetDriver()->ParseOutput(output);
(gdb) p m_State
$3 = {m_pPlugin = 0x8a17bc8, [b]m_pDriver = 0x0,[/b]
  m_Watches = {<wxArrayPtrVoid> = {<wxBaseArrayPtrVoid> = {m_nSize = 0,
        m_nCount = 0, m_pItems = 0x0}, <No data fields>}, <No data fields>},
  m_Breakpoints = {<wxBaseArrayPtrVoid> = {m_nSize = 0, m_nCount = 0,
      m_pItems = 0x0}, <No data fields>}, m_BpAutoIndex = 0}
(gdb) p output
$4 = (const wxString &) @0xbfcdc3cc: {<wxStringBase> = {
    static npos = 4294967295, m_pchData = 0x903b844}, <No data fields>}
(gdb)




Even tho stop has already occured, and m_State is cleared, DebuggerGDB::OnGDBOutput is trying to parse the message:
"Error detected on stdin".

We either have to drain stdin before destroying m_State, or disconnect it somehow.

Code Select Expand


(gdb) f 6
#6  0xb46bdc75 in DebuggerGDB::OnGDBOutput (this=0x8a17918, event=@0x8a29a74)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1916
1916            ParseOutput(msg);
(gdb) l
1911    {
1912        wxString msg = event.GetString();
1913        if (!msg.IsEmpty())
1914        {
1915    //        Manager::Get()->GetMessageManager()->Log(m_PageIndex, _T("O>>> %s"), msg.c_str());
1916            ParseOutput(msg);
1917        }
1918    }
1919
1920    void DebuggerGDB::OnGDBError(wxCommandEvent& event)
(gdb) p msg
$7 = {<wxStringBase> = {static npos = 4294967295,
    m_pchData = 0x90baa14}, <No data fields>}

(gdb) x/80s msg.m_pchData
0x90baa14:       "e"
0x90baa16:       ""
0x90baa17:       ""
0x90baa18:       "r"
0x90baa1a:       ""
0x90baa1b:       ""
0x90baa1c:       "r"
0x90baa1e:       ""
0x90baa1f:       ""
0x90baa20:       "o"
0x90baa22:       ""
0x90baa23:       ""
0x90baa24:       "r"
0x90baa26:       ""
0x90baa27:       ""
0x90baa28:       " "
0x90baa2a:       ""
0x90baa2b:       ""
0x90baa2c:       "d"
0x90baa2e:       ""
0x90baa2f:       ""
0x90baa30:       "e"
0x90baa32:       ""
0x90baa33:       ""
0x90baa34:       "t"
0x90baa36:       ""
0x90baa37:       ""
0x90baa38:       "e"
0x90baa3a:       ""
0x90baa3b:       ""
0x90baa3c:       "c"
0x90baa3e:       ""
0x90baa3f:       ""
0x90baa40:       "t"
0x90baa42:       ""
0x90baa43:       ""
0x90baa44:       "e"
0x90baa46:       ""
0x90baa47:       ""
0x90baa48:       "d"
---Type <return> to continue, or q <return> to quit---
0x90baa4a:       ""
0x90baa4b:       ""
0x90baa4c:       " "
0x90baa4e:       ""
0x90baa4f:       ""
0x90baa50:       "o"
0x90baa52:       ""
0x90baa53:       ""
0x90baa54:       "n"
0x90baa56:       ""
0x90baa57:       ""
0x90baa58:       " "
0x90baa5a:       ""
0x90baa5b:       ""
0x90baa5c:       "s"
0x90baa5e:       ""
0x90baa5f:       ""
0x90baa60:       "t"
0x90baa62:       ""
0x90baa63:       ""
0x90baa64:       "d"
0x90baa66:       ""
0x90baa67:       ""
0x90baa68:       "i"
0x90baa6a:       ""
0x90baa6b:       ""
0x90baa6c:       "n"
0x90baa6e:       ""
0x90baa6f:       ""
0x90baa70:       ""
0x90baa71:       ""
0x90baa72:       ""
0x90baa73:       ""
0x90baa74:       ""
0x90baa75:       ""
0x90baa76:       ""
0x90baa77:       ""
0x90baa78:       ""
0x90baa79:       ""
0x90baa7a:       ""
(


[Pecan]

The line "    m_State.StopDriver();" in debuggergdb.cpp is causing a crash in linux when the user hits the stop debugger button. It clears m_State.m_pDriver which is still being used by the events:

EVT_PIPEDPROCESS_STDOUT(idGDBProcess, DebuggerGDB::OnGDBOutput)
EVT_PIPEDPROCESS_STDERR(idGDBProcess, DebuggerGDB::OnGDBError)

Code Select Expand



void DebuggerGDB::OnGDBTerminated(wxCommandEvent& event)
{
    m_PidToAttach = 0;

    m_TimerPollDebugger.Stop();
    m_LastExitCode = event.GetInt();
    //the process deletes itself
//    m_pProcess = 0L;

    ClearActiveMarkFromAllEditors();
    m_State.StopDriver();
    Manager::Get()->GetMessageManager()->Log(m_PageIndex, _("Debugger finished with status %d"), m_LastExitCode);

    if (m_NoDebugInfo)
    {
        cbMessageBox(_("This project/target has no debugging info."
                        "Please change this in the project's build options and retry..."),
                        _("Error"),
                        wxICON_STOP);
    }

    // switch to the user-defined layout when finished debugging
    DoSwitchLayout(_T("layout_end"));
}



The crashes stop when that line is commented out. But it causes OnProjectActivated and OnProjectClosed to think the project is still in debugging mode.

[Pecan]

I cannot understand this situation. Look at the last line.
The debugger states that "m_State.HasDriver()" is false, yet the call was make anyway. What the hell ???

Code Select Expand


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1231042896 (LWP 5287)]
0xb4641020 in DebuggerDriver::CurrentCommand (this=0x8bf1db8)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) bt
#0  0xb4641020 in DebuggerDriver::CurrentCommand (this=0x8bf1db8)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggerdriver.cpp:98
#1  0xb4666b37 in GDB_driver::ParseOutput (this=0x8bf1db8, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
#2  0xb464484d in DebuggerGDB::ParseOutput (this=0x8a17918, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1543
#3  0xb4646c8c in DebuggerGDB::OnGDBOutput (this=0x8a17918, event=@0xb3c005c4)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1918
#4  0xb792d655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#5  0xb79bcb52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#6  0xb79bcc9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#7  0xb79bce1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#8  0xb79bd2d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#9  0xb792dbef in wxAppConsole::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#10 0xb770a4dd in Manager::ProcessPendingEvents () at sdk/manager.cpp:108
#11 0xb77c94cf in SimpleTextLog::AddLog (this=0x8b24490, msg=@0xbf917b9c,
    addNewLine=true) at sdk/simpletextlog.cpp:70
#12 0xb770f001 in MessageManager::Log (this=0x862afa8, id=6, msg=@0xbf917b9c)
    at sdk/messagemanager.cpp:455
#13 0xb4641f8a in DebuggerGDB::DebugLog (this=0x8a17918, msg=@0xbf917b9c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:566
#14 0xb4666af9 in GDB_driver::ParseOutput (this=0x8bf1db8, output=@0xbf917b9c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:613
#15 0xb464484d in DebuggerGDB::ParseOutput (this=0x8a17918, output=@0xbf917b9c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1543
#16 0xb4646c8c in DebuggerGDB::OnGDBOutput (this=0x8a17918, event=@0xb3c00570)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1918
#17 0xb792d655 in wxAppConsole::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#18 0xb79bcb52 in wxEvtHandler::ProcessEventIfMatches ()
   from /usr/lib/libwx_baseu-2.6.so.0
#19 0xb79bcc9d in wxEventHashTable::HandleEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#20 0xb79bce1f in wxEvtHandler::ProcessEvent ()
   from /usr/lib/libwx_baseu-2.6.so.0
#21 0xb79bd2d0 in wxEvtHandler::ProcessPendingEvents ()
   from /usr/lib/libwx_baseu-2.6.so.0
#22 0xb792dbef in wxAppConsole::ProcessPendingEvents ()
---Type <return> to continue, or q <return> to quit---q
from /usr/lib/libwx_baseQuit
(gdb) f 3
#3  0xb4646c8c in DebuggerGDB::OnGDBOutput (this=0x8a17918, event=@0xb3c005c4)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1918
1918    }
(gdb) p m_state
No symbol "m_state" in current context.
(gdb) p m_State
$1 = {m_pPlugin = 0x8a17918, m_pDriver = 0x0,
  m_Watches = {<wxArrayPtrVoid> = {<wxBaseArrayPtrVoid> = {m_nSize = 0,
        m_nCount = 0, m_pItems = 0x0}, <No data fields>}, <No data fields>},
  m_Breakpoints = {<wxBaseArrayPtrVoid> = {m_nSize = 0, m_nCount = 0,
      m_pItems = 0x0}, <No data fields>}, m_BpAutoIndex = 0}
(gdb) f 2
#2  0xb464484d in DebuggerGDB::ParseOutput (this=0x8a17918, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1543
1543            m_State.GetDriver()->ParseOutput(output);
(gdb) p m_State
$2 = {m_pPlugin = 0x8a17918, m_pDriver = 0x0,
  m_Watches = {<wxArrayPtrVoid> = {<wxBaseArrayPtrVoid> = {m_nSize = 0,
        m_nCount = 0, m_pItems = 0x0}, <No data fields>}, <No data fields>},
  m_Breakpoints = {<wxBaseArrayPtrVoid> = {m_nSize = 0, m_nCount = 0,
      m_pItems = 0x0}, <No data fields>}, m_BpAutoIndex = 0}
(gdb) f 1
#1  0xb4666b37 in GDB_driver::ParseOutput (this=0x8bf1db8, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
620             DebuggerCmd* cmd = CurrentCommand();
(gdb) p m_State
No symbol "m_State" in current context.
(gdb) f
#1  0xb4666b37 in GDB_driver::ParseOutput (this=0x8bf1db8, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
620             DebuggerCmd* cmd = CurrentCommand();
(gdb) f 0
#0  0xb4641020 in DebuggerDriver::CurrentCommand (this=0x8bf1db8)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggerdriver.cpp:98
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
(gdb) p m_DCmds
$3 = {<wxBaseArrayPtrVoid> = {m_nSize = 16, m_nCount = 1,
    m_pItems = 0x0}, <No data fields>}
(gdb) l
93          RunQueue();
94      }
95
96      DebuggerCmd* DebuggerDriver::CurrentCommand()
97      {
98          return m_DCmds.GetCount() ? m_DCmds[0] : 0;
99      }
100
101     void DebuggerDriver::RunQueue()
102     {
(gdb) up
#1  0xb4666b37 in GDB_driver::ParseOutput (this=0x8bf1db8, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/gdb_driver.cpp:620
620             DebuggerCmd* cmd = CurrentCommand();
(gdb) l
615         int idx = buffer.First(GDB_PROMPT);
616         if (idx != wxNOT_FOUND)
617         {
618             m_ProgramIsStopped = true;
619             m_QueueBusy = false;
620             DebuggerCmd* cmd = CurrentCommand();
621             if (cmd)
622             {
623     //            Log(_T("Command parsing output: ") + buffer.Left(idx));
624                 RemoveTopCommand(false);
(gdb) up
#2  0xb464484d in DebuggerGDB::ParseOutput (this=0x8a17918, output=@0xbf91780c)
    at /home/pecan/devel/trunk/src/plugins/debuggergdb/debuggergdb.cpp:1543
1543            m_State.GetDriver()->ParseOutput(output);
(gdb) p m_state
No symbol "m_state" in current context.
(gdb) p m_State
$4 = {m_pPlugin = 0x8a17918, m_pDriver = 0x0,
  m_Watches = {<wxArrayPtrVoid> = {<wxBaseArrayPtrVoid> = {m_nSize = 0,
        m_nCount = 0, m_pItems = 0x0}, <No data fields>}, <No data fields>},
  m_Breakpoints = {<wxBaseArrayPtrVoid> = {m_nSize = 0, m_nCount = 0,
      m_pItems = 0x0}, <No data fields>}, m_BpAutoIndex = 0}
(gdb) l
1538
1539    void DebuggerGDB::ParseOutput(const wxString& output)
1540    {
1541        if (m_State.HasDriver())
1542        {
1543            m_State.GetDriver()->ParseOutput(output);
1544        }
1545    }
1546
1547    void DebuggerGDB::BringAppToFront()
(gdb) p m_State.HasDriver()
$5 = false
(gdb)



[Pecan]

In the pre-waking hours this morning it finally dawned on me what is going on here.

debuggerGDB m_State variables are being manipulated from two different threads without a critical section.

The message queues and mState.m_pDriver (especially) are being changed while m_pProcess (the PipedProcess) functions:

EVT_PIPEDPROCESS_STDOUT(idGDBProcess, DebuggerGDB::OnGDBOutput)
EVT_PIPEDPROCESS_STDERR(idGDBProcess, DebuggerGDB::OnGDBError)

are also changing the queues and depending on the variables pointed to by m_pDriver, which is being cleared by DebuggerGDB.{Stop()|Cleanup()|StopDriver()}

This explains the crashes and the weird freezes and hangs I often get while debugging, because m_pProcess(PipedProcess) is adding messages while DebuggerGDB and gdb_Driver are removing 'em asynchronously.

This is why the message queue shows it has x number of msgs, but that m_pItems\[x\] are empty.

@Yiannis
Do you want to fix this, or would you care for me to try and find a place to add a wxCriticalSection and see how it goes.

[artoj]

Excellent work, thanks Pecan!

[mandrav]

@Yiannis
Do you want to fix this, or would you care for me to try and find a place to add a wxCriticalSection and see how it goes.

Although I have failed to reproduce a crash, I will have a look.
And no threads are used in the debugger plugin AFAIR...

[Pecan]

@Yiannis
Do you want to fix this, or would you care for me to try and find a place to add a wxCriticalSection and see how it goes.

Although I have failed to reproduce a crash, I will have a look.
And no threads are used in the debugger plugin AFAIR...

Code Select Expand


     m_pProcess = new PipedProcess((void**)&m_pProcess, this, idGDBProcess, true, cwd);
    Manager::Get()->GetMessageManager()->AppendLog(m_PageIndex, _("Starting debugger: "));
    m_Pid = wxExecute(cmd, wxEXEC_ASYNC, m_pProcess);


Arn't the above lines creating an asynchronous process that enters DebuggerGDB via OnGDBOutput and OnGDBError as if they are a separate thread?

The GDB traces would suggest that.

[mandrav]

Arn't the above lines creating an asynchronous process that enters DebuggerGDB via OnGDBOutput and OnGDBError as if they are a separate thread?

Technically, no, a separate process is not a different thread.
Let me have a look at your findings though.

[Pecan]

Here is a little console pgm that will crash ever time you hit the Stop button.

Code Select Expand


#include <iostream>
#include <cstdlib>
#include <cstring>

using namespace std;

int upstring(char *value);


int main()
{
        char value[81]={'\0'};
        int upper_count;
        do
    {   cout << "Please type in a String (max. 80 characters): ";
        cin.getline(value, 80);
        upper_count = upstring(value);
        cout << upper_count << " characters are converted" << endl;
        cout << "The new string is now: " << value << endl;
    }while(upper_count);

  return EXIT_SUCCESS;
}

int upstring(char *value)
{
  int i=0;
  while(*value)
  {
    if(islower(*value))
    {
      *value=toupper(*value);
      i++;
    }
  value++;
  }
  return(i);
}                                                           


[Pecan]

Arn't the above lines creating an asynchronous process that enters DebuggerGDB via OnGDBOutput and OnGDBError as if they are a separate thread?

Technically, no, a separate process is not a different thread.
Let me have a look at your findings though.

Ok, I take it back. It's a process acting just like a thread.
Smells like a duck.....

[Pecan]

Until Yiannis comes up with a better and more informed patch, here's a patch that fixes the debugger Stop Button crash on Linux.

Code Select Expand


Index: debuggergdb.cpp
===================================================================
--- debuggergdb.cpp (revision 3558)
+++ debuggergdb.cpp (working copy)
@@ -1503,6 +1503,7 @@

void DebuggerGDB::Stop()
{
+    // m_pProcess is PipedProcess, m_Pid is GDBdebugger
     if (m_pProcess && m_Pid)
     {
         if (IsStopped())
@@ -1534,6 +1535,18 @@
         #endif
         }
     }
+   #if defined(__WXGTK__) //(pecan 2007/2/08)
+    // When PipedProcess and GDB are gone, we can finally
+    // release the GDB_driver
+    if ( !m_pProcess )
+    {
+        if (m_Pid>0)
+         wxKill (m_Pid, wxSIGTERM);
+        m_Pid = 0;
+        m_State.StopDriver();
+    }
+   #endif
+
}

void DebuggerGDB::ParseOutput(const wxString& output)
@@ -1937,7 +1950,17 @@
//    m_pProcess = 0L;

     ClearActiveMarkFromAllEditors();
+
+   #if defined(__WXGTK__)
+    //(pecan 2007/2/07)
+    // Calling m_State.StopDriver() from here causes crashes since
+    // OnGDBOutput() has stacked multiple messages in the system.
+    // and needs the GDB_driver address.
+    //-m_State.StopDriver();
+   #else
     m_State.StopDriver();
+   #endif
+
     Manager::Get()->GetMessageManager()->Log(m_PageIndex, _("Debugger finished with status %d"), m_LastExitCode);

     if (m_NoDebugInfo)
@@ -2056,6 +2079,10 @@
     // allow others to catch this
     event.Skip();

+    #if defined(__WXGTK__)
+     Stop(); //(pecan 2007/2/08)
+    #endif
+
     // when a project is activated and it's not the actively debugged project,
     // ask the user to end debugging or re-activate the debugged project.

@@ -2064,6 +2091,13 @@

     if (event.GetProject() != m_pProject)
     {
+       #if defined(__WXGTK__) //(pecan 2007/2/08)
+        InfoWindow::Display(wxT("Warning"),
+                wxT("You changed the active project while the debugger was active\n"
+                "Debugging will terminate."),
+                6000, 1);
+
+       #else
         wxString msg = _("You can't change the active project while you 're actively debugging another.\n"
                         "Do you want to stop debugging?\n\n"
                         "Click \"Yes\" to stop debugging now or click \"No\" to re-activate the debuggee.");
@@ -2075,6 +2109,7 @@
         {
             Manager::Get()->GetProjectManager()->SetProject(m_pProject);
         }
+        #endif
     }
}

@@ -2083,6 +2118,10 @@
     // allow others to catch this
     event.Skip();

+    #if defined(__WXGTK__)
+     Stop(); //(pecan 2007/2/08)
+    #endif
+
     // remove all search dirs sotred for this project so we don't have conflicts
     // if a newly opened project happens to use the same memory address
     GetSearchDirs(event.GetProject()).clear();
@@ -2100,11 +2139,17 @@

     if (event.GetProject() == m_pProject)
     {
+       #if defined(__WXGTK__) //(pecan 2007/2/08)
+        InfoWindow::Display( wxT("Warning"), _("The project you were debugging has closed.\n"
+                         "The debugging session will terminate immediately."),
+                         6000, 1);
+       #else
         cbMessageBox(_("The project you were debugging has closed.\n"
                         "The debugging session will terminate immediately."),
                     _("Warning"),
                     wxICON_WARNING);
         Stop();
+       #endif
     }
}




The result of all this is that the GDB_driver was being deleted while OnGDBOutput() still had about 5 GDB messages stackup up and being processed.

The delete in OnGDBTerminate() was swiping m_pDriver right out from under an active ParseOutput().