[lldb-dev] Is it ok to use lldb_private from the driver?
Pavel Labath via lldb-dev
lldb-dev at lists.llvm.org
Sun Mar 20 07:01:45 PDT 2016
Are using we using any other signal that SIGINT on windows currently?
I seem to remember all the fancy signals (SIGTSTP, SIGWINCH,...) being
ifdef-ed out on windows. If the only signal we are interested about if
SIGINT, then I think the API should be more higher-level than a
signal() wrapper (SBHostOS::SetInterruptionHandler ?), since you're
never going to get that to behave portably. If there are other signals
used, then I'd be interesting in what they are and how they work on
Another thing: our current signal-handling code is pretty far from
being signal-safe. I was actually considering replacing the current
signal triggering mechanism with something makes sure the execution
happens on a separate thread (on POSIX you can do this with pselect or
sigwait, on windows we have this semantics already IIUC). It would be
great if any API added here did not preclude this.
On 18 March 2016 at 17:44, Greg Clayton via lldb-dev
<lldb-dev at lists.llvm.org> wrote:
>> On Mar 18, 2016, at 10:20 AM, Zachary Turner via lldb-dev <lldb-dev at lists.llvm.org> wrote:
>> Is it ok to add a public API that isn't interfaced to Python? In this case the culprit is the signal() function. Windows doesn't really support signal in the same way that other platforms do, so there's some code in each driver that basically defines a signal function, and then if you're unlucky when you build, or accidentally include the wrong header file (even indirectly), you'll get multiply defined symbol errors.
>> So what I wanted to do was make a Host::Signal() that on Windows had our custom implementation, and on other platforms just called signal. But it returns and accepts function pointers, and making this work through the python api is going to be a big deal, if not flat out impossible.
> Why is this an issue in Python? Doesn't python abstract this for you? Or is it just a NOP on windows??
>> The idea is that instead of writing signal() everywhere, we would write lldb_private::Host::Signal() everywhere instead.
> Is this just to get a callback when a certain signal is sent to a process, like to handle SIGINT?
> Why this is hard to hook through SBHostOS if python doesn't provide an abstraction?
>> On Fri, Mar 18, 2016 at 10:16 AM Jim Ingham <jingham at apple.com> wrote:
>> The driver used to have a bunch of lldb_private stuff in it, mostly to run the event loop, which Greg abstracted into SB API’s a while ago. If it can be avoided, I’d rather not add it back in. Our claim is folks should be able to write their own debugger interfaces (command line or gui) using the SB API’s, so it would be good if we stuck to that discipline as well.
>> I thought that the lldm-mi was pure SB API’s. That seemed a virtue to me.
>> > On Mar 18, 2016, at 9:54 AM, Zachary Turner via lldb-dev <lldb-dev at lists.llvm.org> wrote:
>> > I notice everything uses SB classes only. Is this a hard requirement? We have a bit of cruft in all of the top-level executables (lldb-server, lldb-mi, lldb) that could be shared if we could move it into Host, but then the 3 drivers would have to #include "lldb/Host/Host.h". Note that lldb-mi and lldb-server already do this, it's only lldb that doesn't. Is this ok?
>> > If not, I can always add a method to SBHostOS and just not add a corresponding swig interface definition for it (so it wouldn't be accessible from Python), which would achieve basically the same effect.
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