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* cygtls.cc (_cygtls::handle_threadlist_exception): Make it clear that the 

function never actually returns.
* exceptions.cc (_cygtls::handle_exceptions): Jump out of function rather than
returning to avoid meddling by previously installed exception handlers.
This commit is contained in:
Christopher Faylor 2008-02-27 17:16:46 +00:00
parent ca504a0dee
commit 8ba248a94b
3 changed files with 25 additions and 3 deletions
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8
winsup/cygwin/ChangeLog
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@ -1,3 +1,11 @@
2008-02-27 Christopher Faylor <me+cygwin@cgf.cx>
* cygtls.cc (_cygtls::handle_threadlist_exception): Make it clear that
the function never actually returns.
* exceptions.cc (_cygtls::handle_exceptions): Jump out of function
rather than returning to avoid meddling by previously installed
exception handlers.
2008-02-25 Corinna Vinschen <corinna@vinschen.de> 2008-02-25 Corinna Vinschen <corinna@vinschen.de>
* dcrt0.cc (initial_env): Only use local buffer "buf" if DEBUGGING is * dcrt0.cc (initial_env): Only use local buffer "buf" if DEBUGGING is

4
winsup/cygwin/cygtls.cc
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@ -221,7 +221,7 @@ _cygtls::set_siginfo (sigpacket *pack)
infodata = pack->si; infodata = pack->si;
} }
extern "C" DWORD __stdcall RtlUnwind (void *, void *, void *, DWORD); extern "C" DWORD __stdcall RtlUnwind (void *, void *, void *, DWORD) __attribute__ ((noreturn));
int int
_cygtls::handle_threadlist_exception (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *c, void *) _cygtls::handle_threadlist_exception (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *c, void *)
{ {
@ -248,7 +248,7 @@ _cygtls::handle_threadlist_exception (EXCEPTION_RECORD *e, exception_list *frame
cygheap->threadlist[threadlist_ix]->remove (INFINITE); cygheap->threadlist[threadlist_ix]->remove (INFINITE);
threadlist_ix = 0; threadlist_ix = 0;
RtlUnwind (frame, threadlist_exception_return, e, 0); RtlUnwind (frame, threadlist_exception_return, e, 0);
return 0; /* Never returns */
} }
/* Set up the exception handler for the current thread. The x86 uses segment /* Set up the exception handler for the current thread. The x86 uses segment

16
winsup/cygwin/exceptions.cc
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@ -659,7 +659,21 @@ _cygtls::handle_exceptions (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT
sig_send (NULL, si, &me); // Signal myself sig_send (NULL, si, &me); // Signal myself
me.incyg--; me.incyg--;
e->ExceptionFlags = 0; e->ExceptionFlags = 0;
return 0; /* The OS adds an exception list frame to the stack. It expects to be
able to remove this entry after the exception handler returned.
However, when unwinding to our frame, our frame becomes the uppermost
frame on the stack (%fs:0 points to frame). This way, our frame
is removed from the exception stack and just disappears. So, we can't
just return here or things will be screwed up by the helpful function
in (presumably) ntdll.dll.
So, instead, we will do the equivalent of a longjmp here and return
to the caller without visiting any of the helpful code installed prior
to this function. This should work ok, since a longjmp() out of here has
to work if linux signal semantics are to be maintained. */
SetThreadContext (GetCurrentThread (), in);
return 0; /* Never actually returns. This is just to keep gcc happy. */
} }
/* Utilities to call a user supplied exception handler. */ /* Utilities to call a user supplied exception handler. */