* dcrt0.cc (dll_crt0_0): Install myfault exception handler on x86_64.
* exception.h (exception_list): Typedef as void on x86_64. (exception::handler_installed): Remove. (exception::handle_while_being_debugged): Remove. (exception::myfault_handle): Declare for x86_64. (exception::handle): Declare as ordinary exception handler on x86_64 as well. (exception::exception): Drop previous code (again). Install exception::handle as SEH handler. (exception::install_myfault_handler): New x86_64-only method to install exception::myfault_handle as VEH handler. Explain why. (exception::~exception): For x86_64, define frame end label (again). * exceptions.cc (CYG_EXC_CONTINUE_EXECUTION): Drop definition. (CYG_EXC_CONTINUE_SEARCH): Ditto. (exception::myfault_handle): New x86_64-only method, VEH handler to handle myfault exceptions. (exception::handle): Define as ordinary exception handler on x86_64 as well. Use ExceptionContinueExecution and ExceptionContinueSearch throughout instead of deleted Cygwin macros. Don't handle myfault exceptions on x86_64.
This commit is contained in:
Corinna Vinschen
parent
58cc7a6498
commit
20738749f6
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@ -1,3 +1,26 @@
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2014-03-28 Corinna Vinschen <corinna@vinschen.de>
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* dcrt0.cc (dll_crt0_0): Install myfault exception handler on x86_64.
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* exception.h (exception_list): Typedef as void on x86_64.
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(exception::handler_installed): Remove.
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(exception::handle_while_being_debugged): Remove.
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(exception::myfault_handle): Declare for x86_64.
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(exception::handle): Declare as ordinary exception handler on x86_64
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as well.
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(exception::exception): Drop previous code (again). Install
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exception::handle as SEH handler.
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(exception::install_myfault_handler): New x86_64-only method to
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install exception::myfault_handle as VEH handler. Explain why.
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(exception::~exception): For x86_64, define frame end label (again).
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* exceptions.cc (CYG_EXC_CONTINUE_EXECUTION): Drop definition.
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(CYG_EXC_CONTINUE_SEARCH): Ditto.
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(exception::myfault_handle): New x86_64-only method, VEH handler to
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handle myfault exceptions.
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(exception::handle): Define as ordinary exception handler on x86_64
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as well. Use ExceptionContinueExecution and ExceptionContinueSearch
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throughout instead of deleted Cygwin macros. Don't handle myfault
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exceptions on x86_64.
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2014-03-28 Corinna Vinschen <corinna@vinschen.de>
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* sec_auth.cc (create_token): Initialize lsa handle to NULL, rather than
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@ -795,6 +795,10 @@ dll_crt0_0 ()
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_main_tls = &_my_tls;
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#ifdef __x86_64__
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exception::install_myfault_handler ();
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#endif
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/* Initialize signal processing here, early, in the hopes that the creation
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of a thread early in the process will cause more predictability in memory
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layout for the main thread. */
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@ -104,29 +104,33 @@ typedef struct _exception_list
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} exception_list;
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extern exception_list *_except_list asm ("%fs:0");
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#else
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typedef void exception_list;
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#endif /* !__x86_64 */
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class exception
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{
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#ifdef __x86_64__
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static bool handler_installed;
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static int handle (LPEXCEPTION_POINTERS);
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static int handle_while_being_debugged (LPEXCEPTION_POINTERS);
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static LONG myfault_handle (LPEXCEPTION_POINTERS ep);
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#else
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exception_list el;
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exception_list *save;
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static int handle (EXCEPTION_RECORD *, exception_list *, CONTEXT *, void *);
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#endif /* __x86_64__ */
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static int handle (EXCEPTION_RECORD *, exception_list *, CONTEXT *, void *);
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public:
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exception () __attribute__ ((always_inline))
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{
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/* Install SEH handler. */
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#ifdef __x86_64__
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if (!handler_installed)
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{
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handler_installed = true;
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SetUnhandledExceptionFilter (handle);
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AddVectoredExceptionHandler (1, handle_while_being_debugged);
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}
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asm volatile ("\n\
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1: \n\
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.seh_handler \
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_ZN9exception6handleEP17_EXCEPTION_RECORDPvP8_CONTEXTS2_, \
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@except \n\
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.seh_handlerdata \n\
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.long 1 \n\
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.rva 1b, 2f, 2f, 2f \n\
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.seh_code \n");
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#else
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save = _except_list;
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el.handler = handle;
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@ -134,7 +138,44 @@ public:
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_except_list = ⪙
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#endif /* __x86_64__ */
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};
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#ifndef __x86_64__
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#ifdef __x86_64__
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static void install_myfault_handler () __attribute__ ((always_inline))
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{
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/* Install myfault exception handler as VEH. Here's what happens:
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Some Windows DLLs (advapi32, for instance) are using SEH to catch
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exceptions inside its own functions. If we install a VEH handler
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to catch all exceptions, our Cygwin VEH handler would illegitimatly
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handle exceptions inside of Windows DLLs which are usually handled
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by its own SEH handler. So, for standard exceptions we use an SEH
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handler as installed in the constructor above so as not to override
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the SEH handlers in Windows DLLs.
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But we have a special case, myfault handling. The myfault handling
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catches exceptions inside of the Cygwin DLL, some of them entirely
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expected as in verifyable_object_isvalid. The ultimately right thing
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to do would be to install SEH handlers for each of these cases.
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But there are two problems with that:
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1. It would be a massive and, partially unreliable change in the
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calling functions due to the incomplete SEH support in GCC.
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2. It doesn't always work. Certain DLLs appear to call Cygwin
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functions during DLL initialization while the SEH handler is
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not installed in the active call frame. For these cases we
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need a more generic approach.
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So, what we do here is to install a myfault VEH handler. This
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function is called from dll_crt0_0, so the myfault handler is
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available very early. */
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AddVectoredExceptionHandler (1, myfault_handle);
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}
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~exception () __attribute__ ((always_inline))
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{
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asm volatile ("\n\
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nop \n\
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2: \n\
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nop \n");
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}
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#else
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~exception () __attribute__ ((always_inline)) { _except_list = save; }
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#endif /* !__x86_64__ */
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};
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@ -545,55 +545,43 @@ rtl_unwind (exception_list *frame, PEXCEPTION_RECORD e)
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popl %%ebx \n\
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": : "r" (frame), "r" (e));
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}
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#endif
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/* Main exception handler. */
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#endif /* __x86_64 */
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#ifdef __x86_64__
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#define CYG_EXC_CONTINUE_EXECUTION EXCEPTION_CONTINUE_EXECUTION
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#define CYG_EXC_CONTINUE_SEARCH EXCEPTION_CONTINUE_SEARCH
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bool exception::handler_installed NO_COPY;
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int
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exception::handle_while_being_debugged (LPEXCEPTION_POINTERS ep)
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/* myfault vectored exception handler */
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LONG
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exception::myfault_handle (LPEXCEPTION_POINTERS ep)
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{
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if (being_debugged ())
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return handle (ep);
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return EXCEPTION_CONTINUE_SEARCH;
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}
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int
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exception::handle (LPEXCEPTION_POINTERS ep)
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#else
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#define CYG_EXC_CONTINUE_EXECUTION ExceptionContinueExecution
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#define CYG_EXC_CONTINUE_SEARCH ExceptionContinueSearch
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int
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exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void *)
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#endif
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{
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static bool NO_COPY debugging;
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_cygtls& me = _my_tls;
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if (me.andreas)
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me.andreas->leave (); /* Return from a "san" caught fault */
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return EXCEPTION_CONTINUE_SEARCH;
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}
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#endif /* __x86_64 */
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#ifdef __x86_64__
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EXCEPTION_RECORD *e = ep->ExceptionRecord;
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CONTEXT *in = ep->ContextRecord;
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/* Main exception handler. */
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int
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exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void *)
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{
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static bool NO_COPY debugging;
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_cygtls& me = _my_tls;
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#ifndef __x86_64__
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if (me.andreas)
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me.andreas->leave (); /* Return from a "san" caught fault */
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#endif
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if (debugging && ++debugging < 500000)
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{
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SetThreadPriority (hMainThread, THREAD_PRIORITY_NORMAL);
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return CYG_EXC_CONTINUE_EXECUTION;
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return ExceptionContinueExecution;
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}
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/* If we're exiting, tell Windows to keep looking for an
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exception handler. */
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if (exit_state || e->ExceptionFlags)
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return CYG_EXC_CONTINUE_SEARCH;
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return ExceptionContinueSearch;
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siginfo_t si = {};
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si.si_code = SI_KERNEL;
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@ -662,7 +650,7 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void
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1))
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{
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case MMAP_NORESERVE_COMMITED:
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return CYG_EXC_CONTINUE_EXECUTION;
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return ExceptionContinueExecution;
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case MMAP_RAISE_SIGBUS: /* MAP_NORESERVE page, commit failed, or
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access to mmap page beyond EOF. */
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si.si_signo = SIGBUS;
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@ -696,13 +684,13 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void
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want CloseHandle to return an error. This can be revisited
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if gcc ever supports Windows style structured exception
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handling. */
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return CYG_EXC_CONTINUE_EXECUTION;
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return ExceptionContinueExecution;
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default:
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/* If we don't recognize the exception, we have to assume that
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we are doing structured exception handling, and we let
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something else handle it. */
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return CYG_EXC_CONTINUE_SEARCH;
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return ExceptionContinueSearch;
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}
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debug_printf ("In cygwin_except_handler exception %y at %p sp %p", e->ExceptionCode, in->_GR(ip), in->_GR(sp));
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@ -738,7 +726,7 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void
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else
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{
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debugging = true;
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return CYG_EXC_CONTINUE_EXECUTION;
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return ExceptionContinueExecution;
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}
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/* FIXME: Probably should be handled in signal processing code */
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@ -773,7 +761,7 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in, void
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sig_send (NULL, si, &me); /* Signal myself */
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me.incyg--;
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e->ExceptionFlags = 0;
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return CYG_EXC_CONTINUE_EXECUTION;
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return ExceptionContinueExecution;
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}
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/* Utilities to call a user supplied exception handler. */
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