SAFE_DYNCALLS option

3 files changed, 12 insertions, 1 deletions

diff --git a/src/jsifier.js b/src/jsifier.js
index 5f327076..ff43c8c6 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -1401,6 +1401,8 @@ function JSify(data, functionsOnly, givenFunctions) {
       if (ASM_JS) {
         assert(returnType.search(/\("'\[,/) == -1); // XXX need isFunctionType(type, out)
         callIdent = '(' + callIdent + ')&{{{ FTM_' + sig + ' }}}'; // the function table mask is set in emscripten.py
+      } else if (SAFE_DYNCALLS) {
+        callIdent = '(tempInt=' + callIdent + ',tempInt < 0 || tempInt >= FUNCTION_TABLE.length-1 ? abort("dyncall error") : tempInt)';
       }
       callIdent = Functions.getTable(sig) + '[' + callIdent + ']';
     }
diff --git a/src/modules.js b/src/modules.js
index f3c14cd1..7f8a959b 100644
--- a/src/modules.js
+++ b/src/modules.js
@@ -330,9 +330,16 @@ var Functions = {
           }
         }
       }
+      if (SAFE_DYNCALLS) {
+        assert(!ASM_JS, 'cannot emit safe dyncalls in asm');
+        for (var j = 0; j < table.length; j++) {
+          if (table[j] == 0) {
+            table[j] = "function() { abort('dyncall error') }";
+          }
+        }
+      }
       if (table.length > 20) {
         // add some newlines in the table, for readability
-        table = table.slice(0);
         var j = 10;
         while (j+10 < table.length) {
           table[j] += '\n';
diff --git a/src/settings.js b/src/settings.js
index 21b6abcf..308afddc 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -128,6 +128,8 @@ var SAFE_HEAP = 0; // Check each write to the heap, for example, this will give
                    // that 3 is the option you usually want here.
 var SAFE_HEAP_LOG = 0; // Log out all SAFE_HEAP operations
 
+var SAFE_DYNCALLS = 0; // Show stack traces on missing function pointer/virtual method calls
+
 var ASM_HEAP_LOG = 0; // Simple heap logging, like SAFE_HEAP_LOG but cheaper, and in asm.js
 
 var CORRUPTION_CHECK = 0; // When enabled, will emit a buffer area at the beginning and