Function writeStackCookie

src/runtime_stack_check.js:9–32

()

#if STACK_OVERFLOW_CHECK
// Initializes the stack cookie. Called at the startup of main and at the startup of each thread in pthreads mode.
function writeStackCookie() {
  var max = _emscripten_stack_get_end();
#if RUNTIME_DEBUG
  dbg(`writeStackCookie: ${ptrToString(max)}`);
#endif
#if ASSERTIONS
  assert((max & 3) == 0);
#endif
  // If the stack ends at address zero we write our cookies 4 bytes into the
  // stack.  This prevents interference with SAFE_HEAP and ASAN which also
  // monitor writes to address zero.
  if (max == 0) {
    max += 4;
  }
  // The stack grow downwards towards _emscripten_stack_get_end.
  // We write cookies to the final two words in the stack and detect if they are
  // ever overwritten.
  {{{ makeSetValue('max', 0, '0x02135467', 'u32') }}};
  {{{ makeSetValue('max', 4, '0x89BACDFE', 'u32') }}};
#if CHECK_NULL_WRITES
  // Also test the global address 0 for integrity.
  {{{ makeSetValue(0, 0, 0x63736d65 /* 'emsc' */, 'u32') }}};
#endif
}

function checkStackCookie() {
#if !MINIMAL_RUNTIME