On 01/04/2015 18:36, Jon TURNEY wrote:
On 01/04/2015 15:22, Corinna Vinschen wrote:
On Apr 1 14:19, Jon TURNEY wrote:
Add ucontext.h header, defining ucontext_t and mcontext_t types.
Provide sigaction sighandlers with a ucontext_t parameter, containing
stack and
context information.
* include/sys/ucontext.h : New header.
* include/ucontext.h : Ditto.
* exceptions.cc (call_signal_handler): Provide ucontext_t
parameter to signal handler function.
Patch is ok with a single change: Please add a "FIXME?" comment to:
else
RtlCaptureContext();
On second thought, calling RtlCaptureContext here is probably wrong.
What we really need is the context of the thread when calling
call_signal_handler I think.
I had the same thought, but this is going to be quite tricky to achieve.
It would be better to call RtlCaptureContext
before calling call_signal_handler. But this requires a change in how
call_signal_handler is called.
We should discuss this at one point, I think.
I noticed that we already prepare a context for continuing after the
signal for the debugger, so perhaps this is not quite as complex as I
thought and something like the attached is needed.
It's very hard to reason about if this is doing the right thing when the
signal is delivered across threads, though.
From d6385aa66e26e86832e1e95222e8026146bb63df Mon Sep 17 00:00:00 2001
From: Jon TURNEY <[email protected]>
Date: Thu, 23 Apr 2015 14:45:05 +0100
Subject: [PATCH] Use the same continuation context in a signal as we would
send to the debugger
---
winsup/cygwin/exceptions.cc | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 4a6c21e..c97cc19 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1503,12 +1503,7 @@ _cygtls::call_signal_handler ()
if (thissi.si_cyg)
memcpy (&context.uc_mcontext, ((cygwin_exception
*)thissi.si_cyg)->context(), sizeof(CONTEXT));
else
- {
- /* FIXME: Really this should be the context which the signal
interrupted? */
- memset(&context.uc_mcontext, 0, sizeof(struct __mcontext));
- context.uc_mcontext.ctxflags = CONTEXT_FULL;
- RtlCaptureContext ((CONTEXT *)&context.uc_mcontext);
- }
+ memcpy (&context.uc_mcontext, &thread_context, sizeof(CONTEXT));
/* FIXME: If/when sigaltstack is implemented, this will need to do
something more complicated */
@@ -1549,9 +1544,10 @@ void
_cygtls::signal_debugger (siginfo_t& si)
{
HANDLE th;
- /* If si.si_cyg is set then the signal was already sent to the debugger. */
+ /* If si.si_cyg is set then the signal was caused by an exception which has
+ already been sent to the debugger. */
if (isinitialized () && !si.si_cyg && (th = (HANDLE) *this)
- && being_debugged () && SuspendThread (th) >= 0)
+ && SuspendThread (th) >= 0)
{
CONTEXT c;
c.ContextFlags = CONTEXT_FULL;
--
2.1.4
