[lldb-dev] How to redirect stdin/out/err to different pty?

Sun Mar 23 11:32:16 PDT 2014

Sure, thanks for the help so far
Eran

On Sun, Mar 23, 2014 at 8:31 PM, Piotr Rak <piotr.rak at gmail.com> wrote:

> I am sorry, but nothing obvious comes to me right now, probably you'll
> need to wait for Monday, when people more familiar with lldb will be able
> to help you debug this problem.
>
>
> 2014-03-23 16:07 GMT+01:00 Eran Ifrah <eran.ifrah at gmail.com>:
>
>
>>
>>
>> On Sun, Mar 23, 2014 at 4:29 PM, Piotr Rak <piotr.rak at gmail.com> wrote:
>>
>>> Sorry I misinformed you about posix_spawn - it is not true for Linux and
>>> FreeBSD at least, it will use ordinary fork.
>>>
>>>
>>> 2014-03-23 15:23 GMT+01:00 Piotr Rak <piotr.rak at gmail.com>:
>>>
>>>
>>>> Hi,
>>>>
>>>> 2014-03-23 14:04 GMT+01:00 Eran Ifrah <eran.ifrah at gmail.com>:
>>>>
>>>> Thanks for your pointer Piotr. Here is the code I am using to open a
>>>>> pseudo-terminal (there is the UI part, which I left out):
>>>>>
>>>>>     char __name[128];
>>>>>     memset(__name, 0, sizeof(__name));
>>>>>
>>>>>     int master(-1);
>>>>>     m_slave = -1;
>>>>>     if(openpty(&master, &m_slave, __name, NULL, NULL) != 0)
>>>>>         return wxT("");
>>>>>
>>>>>     // disable ECHO
>>>>>     struct termios termio;
>>>>>     tcgetattr(master, &termio);
>>>>>     termio.c_lflag = ICANON;
>>>>>     termio.c_oflag = ONOCR | ONLRET;
>>>>>     tcsetattr(master, TCSANOW, &termio);
>>>>>
>>>>>     m_tty = wxString(__name, wxConvUTF8);
>>>>>
>>>>> At the end, m_tty contains a string name (e.g. /dev/pts/19 ).
>>>>> Note that the above code works flawlessly when using it with gdb (i.e.
>>>>> if I pass this "/dev/pts/19" to gdb's switch -tty=/dev/pts/19 I will
>>>>> get all the inferior output/err/input to my internal terminal)
>>>>>
>>>>> However, doing the same with LLDB (using C++ API not the command line
>>>>> , i.e. passing "/dev/pts/19" as an argument to SBTarget::Launch(...)) I get
>>>>> nothing as output...
>>>>>
>>>>> Looks sane to me.
>>>>
>>>>
>>>>> Also, I am not sure I am following the idea behind replacing the
>>>>> "Launch" function with my own fork(), looking at the code of Launch()
>>>>> suggests that it does more than a simple fork...
>>>>>
>>>>>
>>>> That was my idea to debug issue if nothing else helps.
>>>> Or rather bisect on which side it really is, sorry if I did not make it
>>>> clear...
>>>> So I was trying suggest replacing SBTarget::Launch with fork,  write to
>>>> child stdout/err, and see if that works alone....
>>>>
>>>> SBTarget::Launch is usually actually posix_spawn right now, it uses
>>>> posix_spawnattr_addopen to open descriptors for your specified paths, and
>>>> should open it 3 times - given current implementation - even it is just one
>>>> file.
>>>>
>>>> Have you inspected SBProcess and SBError returned by SBTarget::Launch?
>>>>
>>>> I checked IsValid() on both and its OK for both. I can actually run
>> "next" Continue etc and seems to be working. Its just that I can't seem to
>> redirect the stdout/err to my own console.
>>
>>
>>  Do you see your inferior process is indeed launching, just not
>>>> displaying anything?
>>>>
>>> Yes, ps -ef shows the debugee
>>
>>>
>>>>  Do you have an option to check if those terminals are actually being
>>>> opened (like examining /proc/<pid>/fd for linux)?
>>>>
>>> The terminal is opened. Like I mentioned in my previous email, using the
>> _same_ code with gdb works
>> I also have a standalone terminal application which I wrote which is also
>> using the same set of classes all of the are working for couple of years
>> now without any problems
>>
>> I also tried this:
>> I typed in my konsole 'tty' and used that as the input for Launch - it
>> also seems to have no effect
>>
>>
>>
>>>> Good luck,
>>>> /Piotr
>>>>
>>>> Any more hints?
>>>>> Eran
>>>>>
>>>>>
>>>>>
>>>>> On Sat, Mar 22, 2014 at 9:36 PM, Piotr Rak <piotr.rak at gmail.com>wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> It should.
>>>>>> Have you opened master pseudoterminal like?:
>>>>>>
>>>>>>  int fd = posix_openpt(flags); // open("/dev/ptmx") might work here
>>>>>> too but less portable;
>>>>>> grantpt(fd);
>>>>>> unlockpt(fd);
>>>>>>
>>>>>> Depending on target you might need some bizarre ioctls here, but
>>>>>> assuming you are using Linux/FreeBSD/MacOSX
>>>>>> you should be fine.
>>>>>>
>>>>>> If you had already master pseudo-terminal file descriptor you can
>>>>>> skip steps above.
>>>>>>
>>>>>> You can use ptsname for master file descriptor it will return you
>>>>>> name of slave pseudo-terminal for your master.
>>>>>> Later you can pass name returned by ptsname(fd) as Launch arguments.
>>>>>>
>>>>>> If above won't work you can try replacing Launch() call with ordinary
>>>>>> fork, and in child process:
>>>>>>
>>>>>> slavefd = open(slavename, O_RDWR);
>>>>>>
>>>>>> dup2(0, slavefd);
>>>>>> dup2(1, slavefd);
>>>>>> dup2(2, slavefd);
>>>>>>
>>>>>> And see if that works alone for you...
>>>>>>
>>>>>> Good luck,
>>>>>> /Piotr
>>>>>>
>>>>>>
>>>>>> 2014-03-22 19:29 GMT+01:00 Eran Ifrah <eran.ifrah at gmail.com>:
>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> I am trying to use the C++ API with good success so far.
>>>>>>> I am now at a point where I want to redirect stdin/out/err of the
>>>>>>> inferior to my application (my application creates a separate pseudo
>>>>>>> terminal window)
>>>>>>>
>>>>>>> Looking at the SBTarget::Launch, I thought that simply passing
>>>>>>> "/dev/pts/<some-number>" as the 3rd, 4th and 5th argument will do the trick
>>>>>>> .. well, it did not.
>>>>>>> I am missing something basic here, can anyone shed some light
>>>>>>> please? or give an example (better) of how to achieve this?
>>>>>>>
>>>>>>> Thanks!
>>>>>>>
>>>>>>> --
>>>>>>> Eran Ifrah
>>>>>>> Author of codelite, a cross platform open source C/C++ IDE:
>>>>>>> http://www.codelite.org
>>>>>>> wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> lldb-dev mailing list
>>>>>>> lldb-dev at cs.uiuc.edu
>>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Eran Ifrah
>>>>> Author of codelite, a cross platform open source C/C++ IDE:
>>>>> http://www.codelite.org
>>>>> wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
>>>>>
>>>>
>>>>
>>>
>>
>>
>> --
>> Eran Ifrah
>> Author of codelite, a cross platform open source C/C++ IDE:
>> http://www.codelite.org
>> wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
>>
>
>

-- 
Eran Ifrah
Author of codelite, a cross platform open source C/C++ IDE:
http://www.codelite.org
wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20140323/70529953/attachment.html>