1 files changed, 8 insertions, 11 deletions
diff --git a/src/preamble.js b/src/preamble.js
index a8f19d64..b3cfca85 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -24,6 +24,8 @@ var ACCEPTABLE_SAFE_HEAP_ERRORS = 0;
 function SAFE_HEAP_ACCESS(dest, type, store, ignore) {
   //if (dest === A_NUMBER) Module.print ([dest, type, store] + ' ' + new Error().stack); // Something like this may be useful, in debugging
 
+  assert(dest >= STACK_ROOT, 'segmentation fault: null pointer, or below normal memory');
+
 #if USE_TYPED_ARRAYS
   // When using typed arrays, reads over the top of TOTAL_MEMORY will fail silently, so we must
   // correct that by growing TOTAL_MEMORY as needed. Without typed arrays, memory is a normal
@@ -639,13 +641,6 @@ var FAST_MEMORY = Module['FAST_MEMORY'] || {{{ FAST_MEMORY }}};
   }
 #endif
 
-var base = intArrayFromString('(null)'); // So printing %s of NULL gives '(null)'
-                                         // Also this ensures we leave 0 as an invalid address, 'NULL'
-STATICTOP = base.length;
-for (var i = 0; i < base.length; i++) {
-  {{{ makeSetValue(0, 'i', 'base[i]', 'i8') }}}
-}
-
 Module['HEAP'] = HEAP;
 #if USE_TYPED_ARRAYS == 1
 Module['IHEAP'] = IHEAP;
@@ -664,7 +659,7 @@ Module['HEAPF32'] = HEAPF32;
 Module['HEAPF64'] = HEAPF64;
 #endif
 
-STACK_ROOT = STACKTOP = Runtime.alignMemory(STATICTOP);
+STACK_ROOT = STACKTOP = Runtime.alignMemory(1);
 STACK_MAX = STACK_ROOT + TOTAL_STACK;
 
 #if USE_TYPED_ARRAYS == 2
@@ -694,6 +689,8 @@ STACK_MAX = tempDoublePtr + 8;
 
 STATICTOP = alignMemoryPage(STACK_MAX);
 
+var nullString = allocate(intArrayFromString('(null)'), 'i8', ALLOC_STATIC);
+
 function callRuntimeCallbacks(callbacks) {
   while(callbacks.length > 0) {
     var callback = callbacks.shift();
@@ -723,9 +720,9 @@ function exitRuntime() {
 }
 
 function String_len(ptr) {
-  var i = 0;
-  while ({{{ makeGetValue('ptr', 'i', 'i8') }}}) i++; // Note: should be |!= 0|, technically. But this helps catch bugs with undefineds
-  return i;
+  var i = ptr;
+  while ({{{ makeGetValue('i++', '0', 'i8') }}}) {}; // Note: should be |!= 0|, technically. But this helps catch bugs with undefineds
+  return i - ptr - 1;
 }
 Module['String_len'] = String_len;