Bug 1148012 - Add a run ID for plugins to differentiate subsequent runs of the same plugins. r=jimm.

Normally, this could be served by the process ID of a plugin, however, run ID is meant
to be consumed by multi-process browser chrome code for telling different runs of a
plugin apart (for example, for searching the DOM for a crashed instance of a plugin,
while ensuring that we don't accidentally find newly spawned instances that have not
crashed). Exposing something as low-level as the process ID to browser chrome code
seemed like Too Much Information. Also, there is the extremely unlikely chance that
a process ID might be re-used immediately after the original process shuts down. This
run ID avoids that case, regardless of how unlikely.

dom/ipc/ContentParent.cpp

@@ -1022,17 +1022,21 @@ ContentParent::RecvGetGMPPluginVersionForAPI(const nsCString& aAPI,
 }
 
 bool
-ContentParent::RecvLoadPlugin(const uint32_t& aPluginId, nsresult* aRv)
+ContentParent::RecvLoadPlugin(const uint32_t& aPluginId, nsresult* aRv, uint32_t* aRunID)
 {
     *aRv = NS_OK;
-    return mozilla::plugins::SetupBridge(aPluginId, this, false, aRv);
+    return mozilla::plugins::SetupBridge(aPluginId, this, false, aRv, aRunID);
 }
 
 bool
 ContentParent::RecvConnectPluginBridge(const uint32_t& aPluginId, nsresult* aRv)
 {
     *aRv = NS_OK;
-    return mozilla::plugins::SetupBridge(aPluginId, this, true, aRv);
+    // We don't need to get the run ID for the plugin, since we already got it
+    // in the first call to SetupBridge in RecvLoadPlugin, so we pass in a dummy
+    // pointer and just throw it away.
+    uint32_t dummy = 0;
+    return mozilla::plugins::SetupBridge(aPluginId, this, true, aRv, &dummy);
 }
 
 bool

dom/ipc/ContentParent.h

@@ -174,7 +174,7 @@ public:
                                                bool* aHasPlugin,
                                                nsCString* aVersion) override;
 
-    virtual bool RecvLoadPlugin(const uint32_t& aPluginId, nsresult* aRv) override;
+    virtual bool RecvLoadPlugin(const uint32_t& aPluginId, nsresult* aRv, uint32_t* aRunID) override;
     virtual bool RecvConnectPluginBridge(const uint32_t& aPluginId, nsresult* aRv) override;
     virtual bool RecvFindPlugins(const uint32_t& aPluginEpoch,
                                  nsTArray<PluginTag>* aPlugins,

dom/ipc/PContent.ipdl

@@ -633,7 +633,7 @@ parent:
      * via bridging. The corresponding PluginModuleChild will live in the plugin
      * process.
      */
-    sync LoadPlugin(uint32_t pluginId) returns (nsresult rv);
+    sync LoadPlugin(uint32_t aPluginId) returns (nsresult aResult, uint32_t aRunID);
 
     /**
      * This call is used by asynchronous plugin instantiation to notify the

dom/plugins/ipc/PluginBridge.h

@@ -17,7 +17,7 @@ namespace plugins {
 
 bool
 SetupBridge(uint32_t aPluginId, dom::ContentParent* aContentParent,
-            bool aForceBridgeNow, nsresult* rv);
+            bool aForceBridgeNow, nsresult* aResult, uint32_t* aRunID);
 
 bool
 FindPluginsForContent(uint32_t aPluginEpoch,

dom/plugins/ipc/PluginModuleParent.cpp

@@ -96,8 +96,13 @@ bool
 mozilla::plugins::SetupBridge(uint32_t aPluginId,
                               dom::ContentParent* aContentParent,
                               bool aForceBridgeNow,
-                              nsresult* rv)
+                              nsresult* rv,
+                              uint32_t* runID)
 {
+    if (NS_WARN_IF(!rv) || NS_WARN_IF(!runID)) {
+        return false;
+    }
+
     PluginModuleChromeParent::ClearInstantiationFlag();
     nsRefPtr<nsPluginHost> host = nsPluginHost::GetInst();
     nsRefPtr<nsNPAPIPlugin> plugin;
@@ -106,6 +111,10 @@ mozilla::plugins::SetupBridge(uint32_t aPluginId,
         return true;
     }
     PluginModuleChromeParent* chromeParent = static_cast<PluginModuleChromeParent*>(plugin->GetLibrary());
+    *rv = chromeParent->GetRunID(runID);
+    if (NS_FAILED(*rv)) {
+        return true;
+    }
     chromeParent->SetContentParent(aContentParent);
     if (!aForceBridgeNow && chromeParent->IsStartingAsync() &&
         PluginModuleChromeParent::DidInstantiate()) {
@@ -365,7 +374,8 @@ PluginModuleContentParent::LoadModule(uint32_t aPluginId)
      */
     dom::ContentChild* cp = dom::ContentChild::GetSingleton();
     nsresult rv;
-    if (!cp->SendLoadPlugin(aPluginId, &rv) ||
+    uint32_t runID;
+    if (!cp->SendLoadPlugin(aPluginId, &rv, &runID) ||
         NS_FAILED(rv)) {
         return nullptr;
     }
@@ -381,6 +391,7 @@ PluginModuleContentParent::LoadModule(uint32_t aPluginId)
     }
 
     parent->mPluginId = aPluginId;
+    parent->mRunID = runID;
 
     return parent;
 }
@@ -644,6 +655,10 @@ PluginModuleContentParent::~PluginModuleContentParent()
     Preferences::UnregisterCallback(TimeoutChanged, kContentTimeoutPref, this);
 }
 
+// We start the Run IDs at 1 so that we can use 0 as a way of detecting
+// errors in retrieving the run ID.
+uint32_t PluginModuleChromeParent::sNextRunID = 1;
+
 bool PluginModuleChromeParent::sInstantiated = false;
 
 PluginModuleChromeParent::PluginModuleChromeParent(const char* aFilePath, uint32_t aPluginId)
@@ -675,6 +690,7 @@ PluginModuleChromeParent::PluginModuleChromeParent(const char* aFilePath, uint32
 {
     NS_ASSERTION(mSubprocess, "Out of memory!");
     sInstantiated = true;
+    mRunID = sNextRunID++;
 
     RegisterSettingsCallbacks();
 
@@ -1499,6 +1515,16 @@ PluginModuleParent::ActorDestroy(ActorDestroyReason why)
     }
 }
 
+nsresult
+PluginModuleParent::GetRunID(uint32_t* aRunID)
+{
+    if (NS_WARN_IF(!aRunID)) {
+      return NS_ERROR_INVALID_POINTER;
+    }
+    *aRunID = mRunID;
+    return NS_OK;
+}
+
 void
 PluginModuleChromeParent::ActorDestroy(ActorDestroyReason why)
 {

dom/plugins/ipc/PluginModuleParent.h

@@ -128,6 +128,8 @@ public:
         return mPluginName + mPluginVersion;
     }
 
+    nsresult GetRunID(uint32_t* aRunID);
+
 protected:
     virtual mozilla::ipc::RacyInterruptPolicy
     MediateInterruptRace(const Message& parent, const Message& child) override
@@ -305,6 +307,7 @@ protected:
     bool              mNPInitialized;
     nsTArray<nsRefPtr<PluginAsyncSurrogate>> mSurrogateInstances;
     nsresult          mAsyncNewRv;
+    uint32_t          mRunID;
 };
 
 class PluginModuleContentParent : public PluginModuleParent
@@ -551,6 +554,7 @@ private:
     dom::ContentParent* mContentParent;
     nsCOMPtr<nsIObserver> mOfflineObserver;
     bool mIsBlocklisted;
+    static uint32_t sNextRunID;
     static bool sInstantiated;
 };