Bug 1668577 - Make child process to send offset to parent process, not index, r=peterv

Differential Revision: https://phabricator.services.mozilla.com/D92074

docshell/base/BrowsingContext.cpp

@@ -2742,15 +2742,15 @@ void BrowsingContext::RemoveFromSessionHistory() {
   }
 }
 
-void BrowsingContext::HistoryGo(int32_t aIndex,
+void BrowsingContext::HistoryGo(int32_t aOffset,
                                 std::function<void(int32_t&&)>&& aResolver) {
   if (XRE_IsContentProcess()) {
     ContentChild::GetSingleton()->SendHistoryGo(
-        this, aIndex, std::move(aResolver),
+        this, aOffset, std::move(aResolver),
         [](mozilla::ipc::
                ResponseRejectReason) { /* FIXME Is ignoring this fine? */ });
   } else {
-    Canonical()->HistoryGo(aIndex, std::move(aResolver));
+    Canonical()->HistoryGo(aOffset, std::move(aResolver));
   }
 }
 

docshell/base/BrowsingContext.h

@@ -707,7 +707,7 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
   Tuple<nsCOMPtr<nsIPrincipal>, nsCOMPtr<nsIPrincipal>>
   GetTriggeringAndInheritPrincipalsForCurrentLoad();
 
-  void HistoryGo(int32_t aIndex, std::function<void(int32_t&&)>&& aResolver);
+  void HistoryGo(int32_t aOffset, std::function<void(int32_t&&)>&& aResolver);
 
   bool ShouldUpdateSessionHistory(uint32_t aLoadType);
 

docshell/base/CanonicalBrowsingContext.cpp

@@ -6,6 +6,7 @@
 
 #include "mozilla/dom/CanonicalBrowsingContext.h"
 
+#include "mozilla/CheckedInt.h"
 #include "mozilla/EventForwards.h"
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/dom/BrowserParent.h"
@@ -654,14 +655,25 @@ void CanonicalBrowsingContext::RemoveFromSessionHistory() {
 }
 
 void CanonicalBrowsingContext::HistoryGo(
-    int32_t aIndex, std::function<void(int32_t&&)>&& aResolver) {
+    int32_t aOffset, std::function<void(int32_t&&)>&& aResolver) {
   nsSHistory* shistory = static_cast<nsSHistory*>(GetSessionHistory());
   if (!shistory) {
     return;
   }
 
+  CheckedInt<int32_t> index = shistory->GetRequestedIndex() >= 0
+                                  ? shistory->GetRequestedIndex()
+                                  : shistory->Index();
+  index += aOffset;
+  if (!index.isValid()) {
+    return;
+  }
+
+  // FIXME userinteraction bits may needs tweaks here.
+
+  // GoToIndex checks that index is >= 0 and < length.
   nsTArray<nsSHistory::LoadEntryResult> loadResults;
-  nsresult rv = shistory->GotoIndex(aIndex, loadResults);
+  nsresult rv = shistory->GotoIndex(index.value(), loadResults);
   if (NS_FAILED(rv)) {
     return;
   }

docshell/base/nsDocShell.cpp

@@ -3362,7 +3362,7 @@ nsDocShell::GotoIndex(int32_t aIndex) {
   NS_ENSURE_TRUE(rootSH, NS_ERROR_FAILURE);
 
   ErrorResult rv;
-  rootSH->GotoIndex(aIndex, rv);
+  rootSH->GotoIndex(aIndex, aIndex - rootSH->Index(), rv);
   return rv.StealNSResult();
 }
 

docshell/shistory/ChildSHistory.cpp

@@ -166,7 +166,7 @@ void ChildSHistory::Go(int32_t aOffset, bool aRequireUserInteraction,
     }
   }
 
-  GotoIndex(index.value(), aRv);
+  GotoIndex(index.value(), aOffset, aRv);
 }
 
 void ChildSHistory::AsyncGo(int32_t aOffset, bool aRequireUserInteraction,
@@ -187,10 +187,11 @@ void ChildSHistory::AsyncGo(int32_t aOffset, bool aRequireUserInteraction,
   NS_DispatchToCurrentThread(asyncNav.forget());
 }
 
-void ChildSHistory::GotoIndex(int32_t aIndex, ErrorResult& aRv) {
+void ChildSHistory::GotoIndex(int32_t aIndex, int32_t aOffset,
+                              ErrorResult& aRv) {
   if (mozilla::SessionHistoryInParent()) {
     nsCOMPtr<nsISHistory> shistory = mHistory;
-    mBrowsingContext->HistoryGo(aIndex, [shistory](int32_t&& aRequestedIndex) {
+    mBrowsingContext->HistoryGo(aOffset, [shistory](int32_t&& aRequestedIndex) {
       // FIXME Should probably only do this for non-fission.
       if (shistory) {
         shistory->InternalSetRequestedIndex(aRequestedIndex);

docshell/shistory/ChildSHistory.h

@@ -70,7 +70,8 @@ class ChildSHistory : public nsISupports, public nsWrapperCache {
   void AsyncGo(int32_t aOffset, bool aRequireUserInteraction,
                CallerType aCallerType, ErrorResult& aRv);
 
-  void GotoIndex(int32_t aIndex, ErrorResult& aRv);
+  // aIndex is the new index, and aOffset is the offset between new and current.
+  void GotoIndex(int32_t aIndex, int32_t aOffset, ErrorResult& aRv);
 
   void RemovePendingHistoryNavigations();
 

dom/ipc/ContentParent.cpp

@@ -6913,10 +6913,10 @@ mozilla::ipc::IPCResult ContentParent::RecvHistoryCommit(
 }
 
 mozilla::ipc::IPCResult ContentParent::RecvHistoryGo(
-    const MaybeDiscarded<BrowsingContext>& aContext, int32_t aIndex,
+    const MaybeDiscarded<BrowsingContext>& aContext, int32_t aOffset,
     HistoryGoResolver&& aResolveRequestedIndex) {
   if (!aContext.IsDiscarded()) {
-    aContext.get_canonical()->HistoryGo(aIndex,
+    aContext.get_canonical()->HistoryGo(aOffset,
                                         std::move(aResolveRequestedIndex));
   }
   return IPC_OK();