[lldb-dev] Stop/Resume process, interrupting I/O

[Mario Zechner]

Just to clarify my use of "interrupted". Of course all threads should be
stopped upon SBProcess::Stop(). However, upon SBProcess:Resume() I/O
operations shouldn't just return due to the SIGSTOP but continue doing what
they did before receiving the signal.

Thanks,
Mario

On Sun, Oct 26, 2014 at 11:56 AM, Mario Zechner <badlogicgames at gmail.com>
wrote:

> Hi,
>
> i'm currently trying to understand how LLDB interrupts/resumes processes.
> To my understanding, the Process implementation sends a SIGSTOP to the
> inferior, which will stop the process. Alternatively, the process may be
> stopped (e.g. breakpoint) while Process::DoHalt is executing, in which case
> the event is marked as interrupted. I have a few questions regarding this:
>
> 1) How can i check wether an event was marked as interrupted via the API?
> SBProcess has a couple of static methods like GetStateFromEvent, but none
> of these allow me to check if the event was marked as interrupted
> 2) SIGSTOP seems to interrupt any I/O call, e.g. getchar, listen, and so
> on. Upon a resume, these functions will simply return (e.g. returning EOF)
> instead of continuing waiting for input. Is there any way to have this not
> happen?
>
> Our problem is, that we need to stop/resume the process to implement parts
> of JDWP (Java debugging wire protocol). Some JDWP commands require us to
> stop the process, read some memory regions and resume the process again,
> letting the inferior think that nothing has happened. All of this should
> not interfere with normal program execution, e.g. a file read shouldn't be
> interrupted because we stopped the inferior via SBProcess:Stop().
>
> As always, thanks for all your help!
>
> ciao,
> Mario
>
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