diff options
Diffstat (limited to 'winsup/cygwin/exception.h')
-rw-r--r-- | winsup/cygwin/exception.h | 66 |
1 files changed, 52 insertions, 14 deletions
diff --git a/winsup/cygwin/exception.h b/winsup/cygwin/exception.h index 80569e8d5..83cb21fcf 100644 --- a/winsup/cygwin/exception.h +++ b/winsup/cygwin/exception.h @@ -104,32 +104,33 @@ typedef struct _exception_list } exception_list; extern exception_list *_except_list asm ("%fs:0"); +#else +typedef void exception_list; #endif /* !__x86_64 */ class exception { #ifdef __x86_64__ - static bool handler_installed; - static int handle (LPEXCEPTION_POINTERS); + static LONG myfault_handle (LPEXCEPTION_POINTERS ep); #else exception_list el; exception_list *save; - static int handle (EXCEPTION_RECORD *, exception_list *, CONTEXT *, void *); #endif /* __x86_64__ */ + static int handle (EXCEPTION_RECORD *, exception_list *, CONTEXT *, void *); public: exception () __attribute__ ((always_inline)) { + /* Install SEH handler. */ #ifdef __x86_64__ - if (!handler_installed) - { - handler_installed = true; - /* The unhandled exception filter goes first. It won't work if the - executable is debugged, but then the vectored continue handler - kicks in. For some reason the vectored continue handler doesn't - get called if no unhandled exception filter is installed. */ - SetUnhandledExceptionFilter (handle); - AddVectoredContinueHandler (1, handle); - } + asm volatile ("\n\ + 1: \n\ + .seh_handler \ + _ZN9exception6handleEP17_EXCEPTION_RECORDPvP8_CONTEXTS2_, \ + @except \n\ + .seh_handlerdata \n\ + .long 1 \n\ + .rva 1b, 2f, 2f, 2f \n\ + .seh_code \n"); #else save = _except_list; el.handler = handle; @@ -137,7 +138,44 @@ public: _except_list = ⪙ #endif /* __x86_64__ */ }; -#ifndef __x86_64__ +#ifdef __x86_64__ + static void install_myfault_handler () __attribute__ ((always_inline)) + { + /* Install myfault exception handler as VEH. Here's what happens: + Some Windows DLLs (advapi32, for instance) are using SEH to catch + exceptions inside its own functions. If we install a VEH handler + to catch all exceptions, our Cygwin VEH handler would illegitimatly + handle exceptions inside of Windows DLLs which are usually handled + by its own SEH handler. So, for standard exceptions we use an SEH + handler as installed in the constructor above so as not to override + the SEH handlers in Windows DLLs. + But we have a special case, myfault handling. The myfault handling + catches exceptions inside of the Cygwin DLL, some of them entirely + expected as in verifyable_object_isvalid. The ultimately right thing + to do would be to install SEH handlers for each of these cases. + But there are two problems with that: + + 1. It would be a massive and, partially unreliable change in the + calling functions due to the incomplete SEH support in GCC. + + 2. It doesn't always work. Certain DLLs appear to call Cygwin + functions during DLL initialization while the SEH handler is + not installed in the active call frame. For these cases we + need a more generic approach. + + So, what we do here is to install a myfault VEH handler. This + function is called from dll_crt0_0, so the myfault handler is + available very early. */ + AddVectoredExceptionHandler (1, myfault_handle); + } + ~exception () __attribute__ ((always_inline)) + { + asm volatile ("\n\ + nop \n\ + 2: \n\ + nop \n"); + } +#else ~exception () __attribute__ ((always_inline)) { _except_list = save; } #endif /* !__x86_64__ */ }; |