Source/JavaScriptCore/runtime/ExceptionFuzz.cpp

/*
 * Copyright (C) 2014, 2016 Apple Inc. All rights reserved.
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#include "config.h"
#include "ExceptionFuzz.h"

#include "Error.h"
#include "JSCInlines.h"
#include "TestRunnerUtils.h"

namespace JSC {

static unsigned s_numberOfExceptionFuzzChecks;
unsigned numberOfExceptionFuzzChecks() { return s_numberOfExceptionFuzzChecks; }

// Call this only if you know that exception fuzzing is enabled.
void doExceptionFuzzing(ExecState* exec, ThrowScope& scope, const char* where, const void* returnPC)
{
    VM& vm = scope.vm();
    ASSERT(Options::useExceptionFuzz());

    DeferGCForAWhile deferGC(vm.heap);
    
    s_numberOfExceptionFuzzChecks++;
    
    unsigned fireTarget = Options::fireExceptionFuzzAt();
    if (fireTarget == s_numberOfExceptionFuzzChecks) {
        printf("JSC EXCEPTION FUZZ: Throwing fuzz exception with call frame %p, seen in %s and return address %p.\n", exec, where, returnPC);
        fflush(stdout);

        // The ThrowScope also checks for unchecked simulated exceptions before throwing a
        // new exception. This ensures that we don't quietly overwrite a pending exception
        // (which should never happen with the only exception being to rethrow the same
        // exception). However, ExceptionFuzz works by intentionally throwing its own exception
        // even when one may already exist. This is ok for ExceptionFuzz testing, but we need
        // to placate the exception check verifier here.
        EXCEPTION_ASSERT(scope.exception() || !scope.exception());

        throwException(exec, scope, createError(exec, "Exception Fuzz"_s));
    }
}

} // namespace JSC