Fix for bug 503166 (XPCStringConvert::ReadableToJSString shouldn't allocate for empty string). r/sr=jst.

--HG--
extra : rebase_source : 76c08ffb3bced708ad8af9626b7dfcb3c3fae28f

js/src/xpconnect/src/xpcconvert.cpp

@@ -330,12 +330,11 @@ XPCConvert::NativeData2JS(XPCCallContext& ccx, jsval* d, const void* s,
                     break;
 
                 if(!p->IsVoid()) {
-                    JSString *str =
-                        XPCStringConvert::ReadableToJSString(cx, *p);
+                    jsval str = XPCStringConvert::ReadableToJSVal(cx, *p);
                     if(!str)
                         return JS_FALSE;
 
-                    *d = STRING_TO_JSVAL(str);
+                    *d = str;
                 }
 
                 // *d is defaulted to JSVAL_NULL so no need to set it

js/src/xpconnect/src/xpcprivate.h

@@ -2935,8 +2935,7 @@ class XPCStringConvert
 {
 public:
 
-    static JSString *ReadableToJSString(JSContext *cx,
-                                        const nsAString &readable);
+    static jsval ReadableToJSVal(JSContext *cx, const nsAString &readable);
 
     static XPCReadableJSStringWrapper *JSStringToReadable(XPCCallContext& ccx,
                                                           JSString *str);

js/src/xpconnect/src/xpcquickstubs.cpp

@@ -1081,10 +1081,10 @@ xpc_qsStringToJsval(JSContext *cx, const nsAString &str, jsval *rval)
         return JS_TRUE;
     }
 
-    JSString *jsstr = XPCStringConvert::ReadableToJSString(cx, str);
+    jsval jsstr = XPCStringConvert::ReadableToJSVal(cx, str);
     if(!jsstr)
         return JS_FALSE;
-    *rval = STRING_TO_JSVAL(jsstr);
+    *rval = jsstr;
     return JS_TRUE;
 }
 

js/src/xpconnect/src/xpcstring.cpp

@@ -75,14 +75,21 @@ XPCStringConvert::ShutdownDOMStringFinalizer()
 
 // convert a readable to a JSString, copying string data
 // static
-JSString *
-XPCStringConvert::ReadableToJSString(JSContext *cx,
-                                     const nsAString &readable)
+jsval
+XPCStringConvert::ReadableToJSVal(JSContext *cx,
+                                  const nsAString &readable)
 {
     JSString *str;
 
     PRUint32 length = readable.Length();
 
+    JSAtom *atom;
+    if (length == 0 && (atom = cx->runtime->atomState.emptyAtom))
+    {
+        NS_ASSERTION(ATOM_IS_STRING(atom), "What kind of atom is this?");
+        return ATOM_KEY(atom);
+    }
+
     nsStringBuffer *buf = nsStringBuffer::FromString(readable);
     if (buf)
     {
@@ -93,7 +100,7 @@ XPCStringConvert::ReadableToJSString(JSContext *cx,
             sDOMStringFinalizerIndex =
                     JS_AddExternalStringFinalizer(DOMStringFinalizer);
             if (sDOMStringFinalizerIndex == -1)
-                return NULL;
+                return JSVAL_NULL;
         }
 
         str = JS_NewExternalString(cx, 
@@ -111,14 +118,14 @@ XPCStringConvert::ReadableToJSString(JSContext *cx,
                                         (JS_malloc(cx, (length + 1) *
                                                       sizeof(jschar)));
         if (!chars)
-            return NULL;
+            return JSVAL_NULL;
 
         if (length && !CopyUnicodeTo(readable, 0,
                                      reinterpret_cast<PRUnichar *>(chars),
                                      length))
         {
             JS_free(cx, chars);
-            return NULL;
+            return JSVAL_NULL;
         }
 
         chars[length] = 0;
@@ -127,7 +134,7 @@ XPCStringConvert::ReadableToJSString(JSContext *cx,
         if (!str)
             JS_free(cx, chars);
     }
-    return str;
+    return STRING_TO_JSVAL(str);
 }
 
 // static

js/src/xpconnect/src/xpcwrappedjs.cpp

@@ -620,12 +620,12 @@ nsXPCWrappedJS::GetProperty(const nsAString & name, nsIVariant **_retval)
     if(!ccx.IsValid())
         return NS_ERROR_UNEXPECTED;
 
-    JSString* jsstr = XPCStringConvert::ReadableToJSString(ccx, name);
+    jsval jsstr = XPCStringConvert::ReadableToJSVal(ccx, name);
     if(!jsstr)
         return NS_ERROR_OUT_OF_MEMORY;
 
     return nsXPCWrappedJSClass::
-        GetNamedPropertyAsVariant(ccx, mJSObj, STRING_TO_JSVAL(jsstr), _retval);
+        GetNamedPropertyAsVariant(ccx, mJSObj, jsstr, _retval);
 }
 
 /***************************************************************************/