Bug 1886922: Do not dereference a Maybe if it is not Some r=mccr8

Differential Revision: https://phabricator.services.mozilla.com/D205409

dom/ipc/ContentParent.cpp

@@ -8093,7 +8093,7 @@ IPCResult ContentParent::RecvRawMessage(
     stack->BorrowFromClonedMessageData(*aStack);
   }
   MMPrinter::Print("ContentParent::RecvRawMessage", aMeta.actorName(),
-                   aMeta.messageName(), *aData);
+                   aMeta.messageName(), aData);
   ReceiveRawMessage(aMeta, std::move(data), std::move(stack));
   return IPC_OK();
 }

dom/ipc/MMPrinter.cpp

@@ -26,8 +26,8 @@ LazyLogModule MMPrinter::sMMLog("MessageManager");
 // the output of the logs into logs more friendly to reading.
 
 /* static */
-void MMPrinter::PrintImpl(char const* aLocation, const nsAString& aMsg,
+Maybe<uint64_t> MMPrinter::PrintHeader(char const* aLocation,
-                          ClonedMessageData const& aData) {
+                                       const nsAString& aMsg) {
   NS_ConvertUTF16toUTF8 charMsg(aMsg);
 
   /*
@@ -43,15 +43,29 @@ void MMPrinter::PrintImpl(char const* aLocation, const nsAString& aMsg,
   char* mmSkipLog = PR_GetEnv("MOZ_LOG_MESSAGEMANAGER_SKIP");
 
   if (mmSkipLog && strstr(mmSkipLog, charMsg.get())) {
-    return;
+    return Nothing();
   }
 
-  uint64_t msg_id = RandomUint64OrDie();
+  uint64_t aMsgId = RandomUint64OrDie();
 
   MOZ_LOG(MMPrinter::sMMLog, LogLevel::Debug,
-          ("%" PRIu64 " %s Message: %s in process type: %s", msg_id, aLocation,
+          ("%" PRIu64 " %s Message: %s in process type: %s", aMsgId, aLocation,
            charMsg.get(), XRE_GetProcessTypeString()));
 
+  return Some(aMsgId);
+}
+
+/* static */
+void MMPrinter::PrintNoData(uint64_t aMsgId) {
+  if (!MOZ_LOG_TEST(sMMLog, LogLevel::Verbose)) {
+    return;
+  }
+  MOZ_LOG(MMPrinter::sMMLog, LogLevel::Verbose,
+          ("%" PRIu64 " (No Data)", aMsgId));
+}
+
+/* static */
+void MMPrinter::PrintData(uint64_t aMsgId, ClonedMessageData const& aData) {
   if (!MOZ_LOG_TEST(sMMLog, LogLevel::Verbose)) {
     return;
   }
@@ -75,8 +89,7 @@ void MMPrinter::PrintImpl(char const* aLocation, const nsAString& aMsg,
   if (rv.Failed()) {
     // In testing, the only reason this would fail was if there was no data in
     // the message; so it seems like this is safe-ish.
-    MOZ_LOG(MMPrinter::sMMLog, LogLevel::Verbose,
+    MMPrinter::PrintNoData(aMsgId);
-            ("%" PRIu64 " (No Data)", msg_id));
     rv.SuppressException();
     return;
   }
@@ -86,7 +99,7 @@ void MMPrinter::PrintImpl(char const* aLocation, const nsAString& aMsg,
   if (!srcString.init(cx, unevalObj)) return;
 
   MOZ_LOG(MMPrinter::sMMLog, LogLevel::Verbose,
-          ("%" PRIu64 " %s", msg_id, NS_ConvertUTF16toUTF8(srcString).get()));
+          ("%" PRIu64 " %s", aMsgId, NS_ConvertUTF16toUTF8(srcString).get()));
 }
 
 }  // namespace mozilla::dom

dom/ipc/MMPrinter.h

@@ -7,6 +7,7 @@
 #ifndef MMPrinter_h
 #define MMPrinter_h
 
+#include "mozilla/Maybe.h"
 #include "mozilla/dom/DOMTypes.h"
 #include "nsString.h"
 
@@ -17,24 +18,40 @@ class MMPrinter {
   static void Print(char const* aLocation, const nsAString& aMsg,
                     ClonedMessageData const& aData) {
     if (MOZ_UNLIKELY(MOZ_LOG_TEST(MMPrinter::sMMLog, LogLevel::Debug))) {
-      MMPrinter::PrintImpl(aLocation, aMsg, aData);
+      Maybe<uint64_t> msgId = MMPrinter::PrintHeader(aLocation, aMsg);
+      if (!msgId.isSome()) {
+        return;
+      }
+      MMPrinter::PrintData(*msgId, aData);
     }
   }
 
   static void Print(char const* aLocation, const nsACString& aActorName,
                     const nsAString& aMessageName,
-                    ClonedMessageData const& aData) {
+                    const Maybe<ClonedMessageData>& aData) {
     if (MOZ_UNLIKELY(MOZ_LOG_TEST(MMPrinter::sMMLog, LogLevel::Debug))) {
-      MMPrinter::PrintImpl(
+      Maybe<uint64_t> msgId = MMPrinter::PrintHeader(
           aLocation,
-          NS_ConvertUTF8toUTF16(aActorName + " - "_ns) + aMessageName, aData);
+          NS_ConvertUTF8toUTF16(aActorName + " - "_ns) + aMessageName);
+
+      if (!msgId.isSome()) {
+        return;
+      }
+
+      if (aData.isSome()) {
+        MMPrinter::PrintData(*msgId, *aData);
+      } else {
+        MMPrinter::PrintNoData(*msgId);
+      }
     }
   }
 
  private:
   static LazyLogModule sMMLog;
-  static void PrintImpl(char const* aLocation, const nsAString& aMsg,
+  static Maybe<uint64_t> PrintHeader(char const* aLocation,
-                        ClonedMessageData const& aData);
+                                     const nsAString& aMsg);
+  static void PrintNoData(uint64_t aMsgId);
+  static void PrintData(uint64_t aMsgId, ClonedMessageData const& aData);
 };
 
 }  // namespace mozilla::dom

dom/ipc/WindowGlobalParent.cpp

@@ -566,7 +566,7 @@ IPCResult WindowGlobalParent::RecvRawMessage(
     stack->BorrowFromClonedMessageData(*aStack);
   }
   MMPrinter::Print("WindowGlobalParent::RecvRawMessage", aMeta.actorName(),
-                   aMeta.messageName(), *aData);
+                   aMeta.messageName(), aData);
   ReceiveRawMessage(aMeta, std::move(data), std::move(stack));
   return IPC_OK();
 }