summaryrefslogtreecommitdiffstats
path: root/netwerk/streamconv/nsStreamConverterService.cpp
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--netwerk/streamconv/nsStreamConverterService.cpp543
1 files changed, 543 insertions, 0 deletions
diff --git a/netwerk/streamconv/nsStreamConverterService.cpp b/netwerk/streamconv/nsStreamConverterService.cpp
new file mode 100644
index 0000000000..ce95bb0404
--- /dev/null
+++ b/netwerk/streamconv/nsStreamConverterService.cpp
@@ -0,0 +1,543 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsComponentManagerUtils.h"
+#include "nsStreamConverterService.h"
+#include "nsIComponentRegistrar.h"
+#include "nsString.h"
+#include "nsAtom.h"
+#include "nsDeque.h"
+#include "nsIInputStream.h"
+#include "nsIStreamConverter.h"
+#include "nsICategoryManager.h"
+#include "nsXPCOM.h"
+#include "nsISupportsPrimitives.h"
+#include "nsTArray.h"
+#include "nsServiceManagerUtils.h"
+#include "nsISimpleEnumerator.h"
+#include "mozilla/UniquePtr.h"
+
+///////////////////////////////////////////////////////////////////
+// Breadth-First-Search (BFS) algorithm state classes and types.
+
+// Used to establish discovered verticies.
+enum BFScolors { white, gray, black };
+
+// BFS hashtable data class.
+struct BFSTableData {
+ nsCString key;
+ BFScolors color;
+ int32_t distance;
+ mozilla::UniquePtr<nsCString> predecessor;
+
+ explicit BFSTableData(const nsACString& aKey)
+ : key(aKey), color(white), distance(-1) {}
+};
+
+////////////////////////////////////////////////////////////
+// nsISupports methods
+NS_IMPL_ISUPPORTS(nsStreamConverterService, nsIStreamConverterService)
+
+////////////////////////////////////////////////////////////
+// nsIStreamConverterService methods
+
+////////////////////////////////////////////////////////////
+// nsStreamConverterService methods
+
+// Builds the graph represented as an adjacency list (and built up in
+// memory using an nsObjectHashtable and nsCOMArray combination).
+//
+// :BuildGraph() consults the category manager for all stream converter
+// CONTRACTIDS then fills the adjacency list with edges.
+// An edge in this case is comprised of a FROM and TO MIME type combination.
+//
+// CONTRACTID format:
+// @mozilla.org/streamconv;1?from=text/html&to=text/plain
+// XXX curently we only handle a single from and to combo, we should repeat the
+// XXX registration process for any series of from-to combos.
+// XXX can use nsTokenizer for this.
+//
+
+nsresult nsStreamConverterService::BuildGraph() {
+ nsresult rv;
+
+ nsCOMPtr<nsICategoryManager> catmgr(
+ do_GetService(NS_CATEGORYMANAGER_CONTRACTID, &rv));
+ if (NS_FAILED(rv)) return rv;
+
+ nsCOMPtr<nsISimpleEnumerator> entries;
+ rv = catmgr->EnumerateCategory(NS_ISTREAMCONVERTER_KEY,
+ getter_AddRefs(entries));
+ if (NS_FAILED(rv)) return rv;
+
+ // go through each entry to build the graph
+ nsCOMPtr<nsISupports> supports;
+ nsCOMPtr<nsISupportsCString> entry;
+ rv = entries->GetNext(getter_AddRefs(supports));
+ while (NS_SUCCEEDED(rv)) {
+ entry = do_QueryInterface(supports);
+
+ // get the entry string
+ nsAutoCString entryString;
+ rv = entry->GetData(entryString);
+ if (NS_FAILED(rv)) return rv;
+
+ // cobble the entry string w/ the converter key to produce a full
+ // contractID.
+ nsAutoCString contractID(NS_ISTREAMCONVERTER_KEY);
+ contractID.Append(entryString);
+
+ // now we've got the CONTRACTID, let's parse it up.
+ rv = AddAdjacency(contractID.get());
+ if (NS_FAILED(rv)) return rv;
+
+ rv = entries->GetNext(getter_AddRefs(supports));
+ }
+
+ return NS_OK;
+}
+
+// XXX currently you can not add the same adjacency (i.e. you can't have
+// multiple
+// XXX stream converters registering to handle the same from-to combination.
+// It's
+// XXX not programatically prohibited, it's just that results are un-predictable
+// XXX right now.
+nsresult nsStreamConverterService::AddAdjacency(const char* aContractID) {
+ nsresult rv;
+ // first parse out the FROM and TO MIME-types.
+
+ nsAutoCString fromStr, toStr;
+ rv = ParseFromTo(aContractID, fromStr, toStr);
+ if (NS_FAILED(rv)) return rv;
+
+ // Each MIME-type is a vertex in the graph, so first lets make sure
+ // each MIME-type is represented as a key in our hashtable.
+
+ nsTArray<RefPtr<nsAtom>>* const fromEdges =
+ mAdjacencyList.GetOrInsertNew(fromStr);
+
+ mAdjacencyList.GetOrInsertNew(toStr);
+
+ // Now we know the FROM and TO types are represented as keys in the hashtable.
+ // Let's "connect" the verticies, making an edge.
+
+ RefPtr<nsAtom> vertex = NS_Atomize(toStr);
+ if (!vertex) return NS_ERROR_OUT_OF_MEMORY;
+
+ NS_ASSERTION(fromEdges, "something wrong in adjacency list construction");
+ if (!fromEdges) return NS_ERROR_FAILURE;
+
+ // XXX(Bug 1631371) Check if this should use a fallible operation as it
+ // pretended earlier.
+ fromEdges->AppendElement(vertex);
+ return NS_OK;
+}
+
+nsresult nsStreamConverterService::ParseFromTo(const char* aContractID,
+ nsCString& aFromRes,
+ nsCString& aToRes) {
+ nsAutoCString ContractIDStr(aContractID);
+
+ int32_t fromLoc = ContractIDStr.Find("from=");
+ int32_t toLoc = ContractIDStr.Find("to=");
+ if (-1 == fromLoc || -1 == toLoc) return NS_ERROR_FAILURE;
+
+ fromLoc = fromLoc + 5;
+ toLoc = toLoc + 3;
+
+ nsAutoCString fromStr, toStr;
+
+ ContractIDStr.Mid(fromStr, fromLoc, toLoc - 4 - fromLoc);
+ ContractIDStr.Mid(toStr, toLoc, ContractIDStr.Length() - toLoc);
+
+ aFromRes.Assign(fromStr);
+ aToRes.Assign(toStr);
+
+ return NS_OK;
+}
+
+using BFSHashTable = nsClassHashtable<nsCStringHashKey, BFSTableData>;
+
+// nsObjectHashtable enumerator functions.
+
+class CStreamConvDeallocator : public nsDequeFunctor<nsCString> {
+ public:
+ void operator()(nsCString* anObject) override { delete anObject; }
+};
+
+// walks the graph using a breadth-first-search algorithm which generates a
+// discovered verticies tree. This tree is then walked up (from destination
+// vertex, to origin vertex) and each link in the chain is added to an
+// nsStringArray. A direct lookup for the given CONTRACTID should be made prior
+// to calling this method in an attempt to find a direct converter rather than
+// walking the graph.
+nsresult nsStreamConverterService::FindConverter(
+ const char* aContractID, nsTArray<nsCString>** aEdgeList) {
+ nsresult rv;
+ if (!aEdgeList) return NS_ERROR_NULL_POINTER;
+ *aEdgeList = nullptr;
+
+ // walk the graph in search of the appropriate converter.
+
+ uint32_t vertexCount = mAdjacencyList.Count();
+ if (0 >= vertexCount) return NS_ERROR_FAILURE;
+
+ // Create a corresponding color table for each vertex in the graph.
+ BFSHashTable lBFSTable;
+ for (const auto& entry : mAdjacencyList) {
+ const nsACString& key = entry.GetKey();
+ MOZ_ASSERT(entry.GetWeak(), "no data in the table iteration");
+ lBFSTable.InsertOrUpdate(key, mozilla::MakeUnique<BFSTableData>(key));
+ }
+
+ NS_ASSERTION(lBFSTable.Count() == vertexCount,
+ "strmconv BFS table init problem");
+
+ // This is our source vertex; our starting point.
+ nsAutoCString fromC, toC;
+ rv = ParseFromTo(aContractID, fromC, toC);
+ if (NS_FAILED(rv)) return rv;
+
+ BFSTableData* data = lBFSTable.Get(fromC);
+ if (!data) {
+ return NS_ERROR_FAILURE;
+ }
+
+ data->color = gray;
+ data->distance = 0;
+ auto* dtorFunc = new CStreamConvDeallocator();
+
+ nsDeque grayQ(dtorFunc);
+
+ // Now generate the shortest path tree.
+ grayQ.Push(new nsCString(fromC));
+ while (0 < grayQ.GetSize()) {
+ nsCString* currentHead = (nsCString*)grayQ.PeekFront();
+ nsTArray<RefPtr<nsAtom>>* data2 = mAdjacencyList.Get(*currentHead);
+ if (!data2) return NS_ERROR_FAILURE;
+
+ // Get the state of the current head to calculate the distance of each
+ // reachable vertex in the loop.
+ BFSTableData* headVertexState = lBFSTable.Get(*currentHead);
+ if (!headVertexState) return NS_ERROR_FAILURE;
+
+ int32_t edgeCount = data2->Length();
+
+ for (int32_t i = 0; i < edgeCount; i++) {
+ nsAtom* curVertexAtom = data2->ElementAt(i);
+ auto* curVertex = new nsCString();
+ curVertexAtom->ToUTF8String(*curVertex);
+
+ BFSTableData* curVertexState = lBFSTable.Get(*curVertex);
+ if (!curVertexState) {
+ delete curVertex;
+ return NS_ERROR_FAILURE;
+ }
+
+ if (white == curVertexState->color) {
+ curVertexState->color = gray;
+ curVertexState->distance = headVertexState->distance + 1;
+ curVertexState->predecessor =
+ mozilla::MakeUnique<nsCString>(*currentHead);
+ grayQ.Push(curVertex);
+ } else {
+ delete curVertex; // if this vertex has already been discovered, we
+ // don't want to leak it. (non-discovered vertex's
+ // get cleaned up when they're popped).
+ }
+ }
+ headVertexState->color = black;
+ nsCString* cur = (nsCString*)grayQ.PopFront();
+ delete cur;
+ cur = nullptr;
+ }
+ // The shortest path (if any) has been generated and is represented by the
+ // chain of BFSTableData->predecessor keys. Start at the bottom and work our
+ // way up.
+
+ // first parse out the FROM and TO MIME-types being registered.
+
+ nsAutoCString fromStr, toMIMEType;
+ rv = ParseFromTo(aContractID, fromStr, toMIMEType);
+ if (NS_FAILED(rv)) return rv;
+
+ // get the root CONTRACTID
+ nsAutoCString ContractIDPrefix(NS_ISTREAMCONVERTER_KEY);
+ auto* shortestPath = new nsTArray<nsCString>();
+
+ data = lBFSTable.Get(toMIMEType);
+ if (!data) {
+ // If this vertex isn't in the BFSTable, then no-one has registered for it,
+ // therefore we can't do the conversion.
+ delete shortestPath;
+ return NS_ERROR_FAILURE;
+ }
+
+ while (data) {
+ if (fromStr.Equals(data->key)) {
+ // found it. We're done here.
+ *aEdgeList = shortestPath;
+ return NS_OK;
+ }
+
+ // reconstruct the CONTRACTID.
+ // Get the predecessor.
+ if (!data->predecessor) break; // no predecessor
+ BFSTableData* predecessorData = lBFSTable.Get(*data->predecessor);
+
+ if (!predecessorData) break; // no predecessor, chain doesn't exist.
+
+ // build out the CONTRACTID.
+ nsAutoCString newContractID(ContractIDPrefix);
+ newContractID.AppendLiteral("?from=");
+
+ newContractID.Append(predecessorData->key);
+
+ newContractID.AppendLiteral("&to=");
+ newContractID.Append(data->key);
+
+ // Add this CONTRACTID to the chain.
+ // XXX(Bug 1631371) Check if this should use a fallible operation as it
+ // pretended earlier.
+ shortestPath->AppendElement(newContractID);
+
+ // move up the tree.
+ data = predecessorData;
+ }
+ delete shortestPath;
+ return NS_ERROR_FAILURE; // couldn't find a stream converter or chain.
+}
+
+/////////////////////////////////////////////////////
+// nsIStreamConverterService methods
+NS_IMETHODIMP
+nsStreamConverterService::CanConvert(const char* aFromType, const char* aToType,
+ bool* _retval) {
+ nsCOMPtr<nsIComponentRegistrar> reg;
+ nsresult rv = NS_GetComponentRegistrar(getter_AddRefs(reg));
+ if (NS_FAILED(rv)) return rv;
+
+ nsAutoCString contractID;
+ contractID.AssignLiteral(NS_ISTREAMCONVERTER_KEY "?from=");
+ contractID.Append(aFromType);
+ contractID.AppendLiteral("&to=");
+ contractID.Append(aToType);
+
+ // See if we have a direct match
+ rv = reg->IsContractIDRegistered(contractID.get(), _retval);
+ if (NS_FAILED(rv)) return rv;
+ if (*_retval) return NS_OK;
+
+ // Otherwise try the graph.
+ rv = BuildGraph();
+ if (NS_FAILED(rv)) return rv;
+
+ nsTArray<nsCString>* converterChain = nullptr;
+ rv = FindConverter(contractID.get(), &converterChain);
+ *_retval = NS_SUCCEEDED(rv);
+
+ delete converterChain;
+ return NS_OK;
+}
+
+NS_IMETHODIMP
+nsStreamConverterService::ConvertedType(const nsACString& aFromType,
+ nsIChannel* aChannel,
+ nsACString& aOutToType) {
+ // first determine whether we can even handle this conversion
+ // build a CONTRACTID
+ nsAutoCString contractID;
+ contractID.AssignLiteral(NS_ISTREAMCONVERTER_KEY "?from=");
+ contractID.Append(aFromType);
+ contractID.AppendLiteral("&to=*/*");
+ const char* cContractID = contractID.get();
+
+ nsresult rv;
+ nsCOMPtr<nsIStreamConverter> converter(do_CreateInstance(cContractID, &rv));
+ if (NS_SUCCEEDED(rv)) {
+ return converter->GetConvertedType(aFromType, aChannel, aOutToType);
+ }
+ return rv;
+}
+
+NS_IMETHODIMP
+nsStreamConverterService::Convert(nsIInputStream* aFromStream,
+ const char* aFromType, const char* aToType,
+ nsISupports* aContext,
+ nsIInputStream** _retval) {
+ if (!aFromStream || !aFromType || !aToType || !_retval) {
+ return NS_ERROR_NULL_POINTER;
+ }
+ nsresult rv;
+
+ // first determine whether we can even handle this conversion
+ // build a CONTRACTID
+ nsAutoCString contractID;
+ contractID.AssignLiteral(NS_ISTREAMCONVERTER_KEY "?from=");
+ contractID.Append(aFromType);
+ contractID.AppendLiteral("&to=");
+ contractID.Append(aToType);
+ const char* cContractID = contractID.get();
+
+ nsCOMPtr<nsIStreamConverter> converter(do_CreateInstance(cContractID, &rv));
+ if (NS_FAILED(rv)) {
+ // couldn't go direct, let's try walking the graph of converters.
+ rv = BuildGraph();
+ if (NS_FAILED(rv)) return rv;
+
+ nsTArray<nsCString>* converterChain = nullptr;
+
+ rv = FindConverter(cContractID, &converterChain);
+ if (NS_FAILED(rv)) {
+ // can't make this conversion.
+ // XXX should have a more descriptive error code.
+ return NS_ERROR_FAILURE;
+ }
+
+ int32_t edgeCount = int32_t(converterChain->Length());
+ NS_ASSERTION(edgeCount > 0, "findConverter should have failed");
+
+ // convert the stream using each edge of the graph as a step.
+ // this is our stream conversion traversal.
+ nsCOMPtr<nsIInputStream> dataToConvert = aFromStream;
+ nsCOMPtr<nsIInputStream> convertedData;
+
+ for (int32_t i = edgeCount - 1; i >= 0; i--) {
+ const char* lContractID = converterChain->ElementAt(i).get();
+
+ converter = do_CreateInstance(lContractID, &rv);
+
+ if (NS_FAILED(rv)) {
+ delete converterChain;
+ return rv;
+ }
+
+ nsAutoCString fromStr, toStr;
+ rv = ParseFromTo(lContractID, fromStr, toStr);
+ if (NS_FAILED(rv)) {
+ delete converterChain;
+ return rv;
+ }
+
+ rv = converter->Convert(dataToConvert, fromStr.get(), toStr.get(),
+ aContext, getter_AddRefs(convertedData));
+ dataToConvert = convertedData;
+ if (NS_FAILED(rv)) {
+ delete converterChain;
+ return rv;
+ }
+ }
+
+ delete converterChain;
+ convertedData.forget(_retval);
+ } else {
+ // we're going direct.
+ rv = converter->Convert(aFromStream, aFromType, aToType, aContext, _retval);
+ }
+
+ return rv;
+}
+
+NS_IMETHODIMP
+nsStreamConverterService::AsyncConvertData(const char* aFromType,
+ const char* aToType,
+ nsIStreamListener* aListener,
+ nsISupports* aContext,
+ nsIStreamListener** _retval) {
+ if (!aFromType || !aToType || !aListener || !_retval) {
+ return NS_ERROR_NULL_POINTER;
+ }
+
+ nsresult rv;
+
+ // first determine whether we can even handle this conversion
+ // build a CONTRACTID
+ nsAutoCString contractID;
+ contractID.AssignLiteral(NS_ISTREAMCONVERTER_KEY "?from=");
+ contractID.Append(aFromType);
+ contractID.AppendLiteral("&to=");
+ contractID.Append(aToType);
+ const char* cContractID = contractID.get();
+
+ nsCOMPtr<nsIStreamConverter> listener(do_CreateInstance(cContractID, &rv));
+ if (NS_FAILED(rv)) {
+ // couldn't go direct, let's try walking the graph of converters.
+ rv = BuildGraph();
+ if (NS_FAILED(rv)) return rv;
+
+ nsTArray<nsCString>* converterChain = nullptr;
+
+ rv = FindConverter(cContractID, &converterChain);
+ if (NS_FAILED(rv)) {
+ // can't make this conversion.
+ // XXX should have a more descriptive error code.
+ return NS_ERROR_FAILURE;
+ }
+
+ // aListener is the listener that wants the final, converted, data.
+ // we initialize finalListener w/ aListener so it gets put at the
+ // tail end of the chain, which in the loop below, means the *first*
+ // converter created.
+ nsCOMPtr<nsIStreamListener> finalListener = aListener;
+
+ // convert the stream using each edge of the graph as a step.
+ // this is our stream conversion traversal.
+ int32_t edgeCount = int32_t(converterChain->Length());
+ NS_ASSERTION(edgeCount > 0, "findConverter should have failed");
+ for (int i = 0; i < edgeCount; i++) {
+ const char* lContractID = converterChain->ElementAt(i).get();
+
+ // create the converter for this from/to pair
+ nsCOMPtr<nsIStreamConverter> converter(do_CreateInstance(lContractID));
+ NS_ASSERTION(converter,
+ "graph construction problem, built a contractid that wasn't "
+ "registered");
+
+ nsAutoCString fromStr, toStr;
+ rv = ParseFromTo(lContractID, fromStr, toStr);
+ if (NS_FAILED(rv)) {
+ delete converterChain;
+ return rv;
+ }
+
+ // connect the converter w/ the listener that should get the converted
+ // data.
+ rv = converter->AsyncConvertData(fromStr.get(), toStr.get(),
+ finalListener, aContext);
+ if (NS_FAILED(rv)) {
+ delete converterChain;
+ return rv;
+ }
+
+ // the last iteration of this loop will result in finalListener
+ // pointing to the converter that "starts" the conversion chain.
+ // this converter's "from" type is the original "from" type. Prior
+ // to the last iteration, finalListener will continuously be wedged
+ // into the next listener in the chain, then be updated.
+ finalListener = converter;
+ }
+ delete converterChain;
+ // return the first listener in the chain.
+ finalListener.forget(_retval);
+ } else {
+ // we're going direct.
+ rv = listener->AsyncConvertData(aFromType, aToType, aListener, aContext);
+ listener.forget(_retval);
+ }
+
+ return rv;
+}
+
+nsresult NS_NewStreamConv(nsStreamConverterService** aStreamConv) {
+ MOZ_ASSERT(aStreamConv != nullptr, "null ptr");
+ if (!aStreamConv) return NS_ERROR_NULL_POINTER;
+
+ RefPtr<nsStreamConverterService> conv = new nsStreamConverterService();
+ conv.forget(aStreamConv);
+
+ return NS_OK;
+}