Catch a corner case with 0 in varargs

3 files changed, 18 insertions, 9 deletions

diff --git a/src/parser.js b/src/parser.js
index 94be1dc6..e4beee08 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -2447,10 +2447,12 @@ function JSify(data) {
   function makeFunctionCall(ident, params) {
     // Special cases
     if (ident == '_llvm_va_start') {
+      var args = 'Array.prototype.slice.call(arguments, __numArgs__)';
+      var data = 'Pointer_make([' + args + '.length].concat(' + args + '), 0)';
       if (SAFE_HEAP) {
-        return 'SAFE_HEAP_STORE(' + params[0].ident + ', Pointer_make(Array.prototype.slice.call(arguments, __numArgs__).concat([0]), 0))';
+        return 'SAFE_HEAP_STORE(' + params[0].ident + ', ' + data + ', 0)';
       } else {
-        return 'HEAP[' + params[0].ident + '] = Pointer_make(Array.prototype.slice.call(arguments, __numArgs__).concat([0]), 0)';
+        return 'HEAP[' + params[0].ident + '] = ' + data;
       }
     } else if (ident == '_llvm_va_end') {
       return ';'
diff --git a/src/preamble.js b/src/preamble.js
index 4d473ee3..2ededac1 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -173,9 +173,18 @@ function _strlen(p) {
 //  return p.slab.length; // XXX might want to find the null terminator...
 }
 
-function String_copy(p, addZero) {
+// Copies a list of num items on the HEAP into a
+// a normal JavaScript array of numbers
+function Array_copy(ptr, num) {
   // XXX hardcoded ptr impl
-  return HEAP.slice(p, p+_strlen(p)).concat(addZero ? [0] : []);
+  return HEAP.slice(ptr, ptr+num);
+}
+
+// Copies a C-style string, terminated by a zero, from the HEAP into
+// a normal JavaScript array of numbers
+function String_copy(ptr, addZero) {
+  // XXX hardcoded ptr impl
+  return Array_copy(ptr, _strlen(ptr)).concat(addZero ? [0] : []);
 }
 
 // stdlib.h
@@ -215,6 +224,8 @@ function jrint(label, obj) {
   print(label + JSON.stringify(obj));
 }
 
+// This processes a 'normal' string into a C-line array of numbers.
+// For LLVM-originating strings, see parser.js:parseLLVMString function
 function intArrayFromString(stringy) {
   var ret = [];
   var t;
diff --git a/src/snippets.js b/src/snippets.js
index 96420990..2f60015f 100644
--- a/src/snippets.js
+++ b/src/snippets.js
@@ -1,10 +1,6 @@
 var Snippets = {
   vsnprintf: function(dst, num, src, ptr) {
-    var args = [];
-    while (HEAP[ptr] != 0) {
-      args.push(HEAP[ptr]);
-      ptr ++;
-    }
+    var args = Array_copy(ptr+1, HEAP[ptr]); // # of args in in first place
     var text = __formatString.apply(null, [src].concat(args));
     for (var i = 0; i < num; i++) {
       HEAP[dst+i] = HEAP[text+i];