Bug 777528 - Expose compartment names to the JS engine (r=luke)

js/src/jsapi.cpp

@@ -731,6 +731,7 @@ JSRuntime::JSRuntime()
     interpreterFrames(NULL),
     cxCallback(NULL),
     destroyCompartmentCallback(NULL),
+    compartmentNameCallback(NULL),
     activityCallback(NULL),
     activityCallbackArg(NULL),
 #ifdef JS_THREADSAFE
@@ -1398,6 +1399,12 @@ JS_SetDestroyCompartmentCallback(JSRuntime *rt, JSDestroyCompartmentCallback cal
     rt->destroyCompartmentCallback = callback;
 }
 
+JS_PUBLIC_API(void)
+JS_SetCompartmentNameCallback(JSRuntime *rt, JSCompartmentNameCallback callback)
+{
+    rt->compartmentNameCallback = callback;
+}
+
 JS_PUBLIC_API(JSWrapObjectCallback)
 JS_SetWrapObjectCallbacks(JSRuntime *rt,
                           JSWrapObjectCallback callback,

js/src/jsapi.h

@@ -2007,6 +2007,10 @@ typedef JSObject *
 typedef void
 (* JSDestroyCompartmentCallback)(JSFreeOp *fop, JSCompartment *compartment);
 
+typedef void
+(* JSCompartmentNameCallback)(JSRuntime *rt, JSCompartment *compartment,
+                              char *buf, size_t bufsize);
+
 /*
  * Read structured data from the reader r. This hook is used to read a value
  * previously serialized by a call to the WriteStructuredCloneOp hook.
@@ -3119,6 +3123,9 @@ JS_GetImplementationVersion(void);
 extern JS_PUBLIC_API(void)
 JS_SetDestroyCompartmentCallback(JSRuntime *rt, JSDestroyCompartmentCallback callback);
 
+extern JS_PUBLIC_API(void)
+JS_SetCompartmentNameCallback(JSRuntime *rt, JSCompartmentNameCallback callback);
+
 extern JS_PUBLIC_API(JSWrapObjectCallback)
 JS_SetWrapObjectCallbacks(JSRuntime *rt,
                           JSWrapObjectCallback callback,

js/src/jscntxt.h

@@ -447,6 +447,9 @@ struct JSRuntime : js::RuntimeFriendFields
     /* Compartment destroy callback. */
     JSDestroyCompartmentCallback destroyCompartmentCallback;
 
+    /* Call this to get the name of a compartment. */
+    JSCompartmentNameCallback compartmentNameCallback;
+
     js::ActivityCallback  activityCallback;
     void                 *activityCallbackArg;
 

js/xpconnect/src/XPCJSRuntime.cpp

@@ -1112,7 +1112,7 @@ XPCJSRuntime::~XPCJSRuntime()
 }
 
 static void
-GetCompartmentName(JSCompartment *c, nsCString &name)
+GetCompartmentName(JSCompartment *c, nsCString &name, bool replaceSlashes)
 {
     if (js::IsAtomsCompartment(c)) {
         name.AssignLiteral("atoms");
@@ -1131,11 +1131,12 @@ GetCompartmentName(JSCompartment *c, nsCString &name)
                 name.Append(location);
             }
         }
-        
+
         // A hack: replace forward slashes with '\\' so they aren't
         // treated as path separators.  Users of the reporters
         // (such as about:memory) have to undo this change.
-        name.ReplaceChar('/', '\\');
+        if (replaceSlashes)
+            name.ReplaceChar('/', '\\');
     } else {
         name.AssignLiteral("null-principal");
     }
@@ -1611,7 +1612,7 @@ class JSCompartmentsMultiReporter MOZ_FINAL : public nsIMemoryMultiReporter
         // silently ignore OOM errors
         Paths *paths = static_cast<Paths *>(data);
         nsCString path;
-        GetCompartmentName(c, path);
+        GetCompartmentName(c, path, true);
         path.Insert(js::IsSystemCompartment(c)
                     ? NS_LITERAL_CSTRING("compartments/system/")
                     : NS_LITERAL_CSTRING("compartments/user/"),
@@ -1724,7 +1725,7 @@ class XPCJSRuntimeStats : public JS::RuntimeStats
                                            JS::CompartmentStats *cstats) MOZ_OVERRIDE {
         nsCAutoString cJSPathPrefix, cDOMPathPrefix;
         nsCString cName;
-        GetCompartmentName(c, cName);
+        GetCompartmentName(c, cName, true);
 
         // Get the compartment's global.
         nsXPConnect *xpc = nsXPConnect::GetXPConnect();
@@ -1940,6 +1941,17 @@ AccumulateTelemetryCallback(int id, uint32_t sample)
     }
 }
 
+static void
+CompartmentNameCallback(JSRuntime *rt, JSCompartment *comp,
+                        char *buf, size_t bufsize)
+{
+    nsCString name;
+    GetCompartmentName(comp, name, false);
+    if (name.Length() >= bufsize)
+        name.Truncate(bufsize - 1);
+    memcpy(buf, name.get(), name.Length() + 1);
+}
+
 bool XPCJSRuntime::gNewDOMBindingsEnabled;
 bool XPCJSRuntime::gExperimentalBindingsEnabled;
 
@@ -2027,6 +2039,7 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
 #endif
     JS_SetContextCallback(mJSRuntime, ContextCallback);
     JS_SetDestroyCompartmentCallback(mJSRuntime, CompartmentDestroyedCallback);
+    JS_SetCompartmentNameCallback(mJSRuntime, CompartmentNameCallback);
     JS_SetGCCallback(mJSRuntime, GCCallback);
     JS_SetFinalizeCallback(mJSRuntime, FinalizeCallback);
     JS_SetExtraGCRootsTracer(mJSRuntime, TraceBlackJS, this);