wasmer/lib/win-exception-handler/exception_handling/exception_handling.c
2019-02-14 09:58:33 -08:00

75 lines
2.5 KiB
C

#include <windows.h>
#include <setjmp.h>
#include "exception_handling.h"
#define CALL_FIRST 1
__declspec(thread) jmp_buf jmpBuf;
__declspec(thread) PVOID caughtExceptionAddress;
__declspec(thread) DWORD64 caughtInstructionPointer;
__declspec(thread) PVOID savedStackPointer;
__declspec(thread) BOOL exceptionHandlerInstalled = FALSE;
__declspec(thread) BOOL alreadyHandlingException = FALSE;
void longjmpOutOfHere() {
longjmp(jmpBuf, 1);
}
/// Get the current address that we use to jmp, the no inline is important
static __declspec(noinline) void *get_callee_frame_address(void) {
return _AddressOfReturnAddress();
}
static LONG WINAPI
exceptionHandler(struct _EXCEPTION_POINTERS *ExceptionInfo) {
EXCEPTION_RECORD* pExceptionRecord = ExceptionInfo->ExceptionRecord;
PCONTEXT pCONTEXT = ExceptionInfo->ContextRecord;
caughtExceptionAddress = pExceptionRecord->ExceptionAddress;
caughtInstructionPointer = pCONTEXT->Rip;
if (alreadyHandlingException == TRUE) {
return EXCEPTION_CONTINUE_SEARCH;
}
alreadyHandlingException = TRUE;
// Basically, here, we coerce the os to resume us into a context that calls `longjmp` instead of just continuing.
// Presumably, we cannot `longjmp` out of the signal/exception context, like we can on unix.
pCONTEXT->Rip = (uintptr_t)(&longjmpOutOfHere);
pCONTEXT->Rsp = (uintptr_t)(savedStackPointer);
return EXCEPTION_CONTINUE_EXECUTION;
}
uint8_t callProtected(trampoline_t trampoline,
const struct wasmer_instance_context_t* ctx,
const struct func_t* func,
const uint64_t* param_vec,
uint64_t* return_vec,
struct call_protected_result_t* out_result) {
// install exception handler
if (exceptionHandlerInstalled == FALSE) {
exceptionHandlerInstalled = TRUE;
AddVectoredExceptionHandler(CALL_FIRST, exceptionHandler);
}
// jmp jmp jmp!
int signum = setjmp(jmpBuf);
if (signum == 0) {
// save the stack pointer
savedStackPointer = get_callee_frame_address();
trampoline(ctx, func, param_vec, return_vec);
out_result->code = 0;
out_result->exceptionAddress = 0;
out_result->instructionPointer = 0;
return TRUE;
}
out_result->code = (uint64_t)signum;
out_result->exceptionAddress = (uint64_t)caughtExceptionAddress;
out_result->instructionPointer = caughtInstructionPointer;
caughtExceptionAddress = 0;
caughtInstructionPointer = 0;
return FALSE;
}