The Tor Browser: netwerk/streamconv/src/nsStreamConverterService.cpp@b8a032363ba2 (annotated)

netwerk/streamconv/src/nsStreamConverterService.cpp@b8a032363ba2 (annotated)

netwerk/streamconv/src/nsStreamConverterService.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- 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/.
  *
  *
  * This Original Code has been modified by IBM Corporation.
  * Modifications made by IBM described herein are
  * Copyright (c) International Business Machines
  * Corporation, 2000
  *
  * Modifications to Mozilla code or documentation
  * identified per MPL Section 3.3
  *
  * Date         Modified by     Description of modification
  * 03/27/2000   IBM Corp.       Added PR_CALLBACK for Optlink
  *                               use in OS2
  */
 #include "nsStreamConverterService.h"
 #include "nsIComponentRegistrar.h"
 #include "nsAutoPtr.h"
 #include "nsString.h"
 #include "nsIAtom.h"
 #include "nsDeque.h"
 #include "nsIInputStream.h"
 #include "nsIStreamConverter.h"
 #include "nsICategoryManager.h"
 #include "nsXPCOM.h"
 #include "nsISupportsPrimitives.h"
 #include "nsCOMArray.h"
 #include "nsTArray.h"
 #include "nsServiceManagerUtils.h"
 #include "nsHashtable.h"
 #include "nsISimpleEnumerator.h"
 ///////////////////////////////////////////////////////////////////
 // Breadth-First-Search (BFS) algorithm state classes and types.
 // Adjacency list data class.
 typedef nsCOMArray<nsIAtom> SCTableData;
 // Delete all the entries in the adjacency list
 static bool DeleteAdjacencyEntry(nsHashKey *aKey, void *aData, void* closure) {
     SCTableData *entry = (SCTableData*)aData;
     delete entry;
     return true;
 }
 // Used to establish discovered verticies.
 enum BFScolors {white, gray, black};
 // BFS hashtable data class.
 struct BFSTableData {
     nsCStringKey *key;
     BFScolors color;
     int32_t distance;
     nsAutoPtr<nsCStringKey> predecessor;
     explicit BFSTableData(nsCStringKey* aKey)
       : key(aKey), color(white), distance(-1)
     {
     }
 };
 ////////////////////////////////////////////////////////////
 // nsISupports methods
 NS_IMPL_ISUPPORTS(nsStreamConverterService, nsIStreamConverterService)
 ////////////////////////////////////////////////////////////
 // nsIStreamConverterService methods
 ////////////////////////////////////////////////////////////
 // nsStreamConverterService methods
 nsStreamConverterService::nsStreamConverterService()
   : mAdjacencyList(nullptr, nullptr, DeleteAdjacencyEntry, nullptr)
 {
 }
 nsStreamConverterService::~nsStreamConverterService() {
 }
 // Builds the graph represented as an adjacency list (and built up in
 // memory using an nsObjectHashtable and nsISupportsArray 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.
     nsCStringKey fromKey(fromStr);
     SCTableData *fromEdges = (SCTableData*)mAdjacencyList.Get(&fromKey);
     if (!fromEdges) {
         // There is no fromStr vertex, create one.
         fromEdges = new SCTableData();
         mAdjacencyList.Put(&fromKey, fromEdges);
     }
     nsCStringKey toKey(toStr);
     if (!mAdjacencyList.Get(&toKey)) {
         // There is no toStr vertex, create one.
         mAdjacencyList.Put(&toKey, new SCTableData());
     }
     // Now we know the FROM and TO types are represented as keys in the hashtable.
     // Let's "connect" the verticies, making an edge.
     nsCOMPtr<nsIAtom> vertex = do_GetAtom(toStr);
     if (!vertex) return NS_ERROR_OUT_OF_MEMORY;
     NS_ASSERTION(fromEdges, "something wrong in adjacency list construction");
     if (!fromEdges)
         return NS_ERROR_FAILURE;
     return fromEdges->AppendObject(vertex) ? NS_OK : NS_ERROR_FAILURE;
 }
 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;
 }
 // nsObjectHashtable enumerator functions.
 // Initializes the BFS state table.
 static bool InitBFSTable(nsHashKey *aKey, void *aData, void* closure) {
     NS_ASSERTION((SCTableData*)aData, "no data in the table enumeration");
     nsHashtable *BFSTable = (nsHashtable*)closure;
     if (!BFSTable) return false;
     BFSTable->Put(aKey, new BFSTableData(static_cast<nsCStringKey*>(aKey)));
     return true;
 }
 // cleans up the BFS state table
 static bool DeleteBFSEntry(nsHashKey *aKey, void *aData, void *closure) {
     BFSTableData *data = (BFSTableData*)aData;
     data->key = nullptr;
     delete data;
     return true;
 }
 class CStreamConvDeallocator : public nsDequeFunctor {
 public:
     virtual void* operator()(void* anObject) {
         nsCStringKey *key = (nsCStringKey*)anObject;
         delete key;
         return 0;
     }
 };
 // 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.
     int32_t vertexCount = mAdjacencyList.Count();
     if (0 >= vertexCount) return NS_ERROR_FAILURE;
     // Create a corresponding color table for each vertex in the graph.
     nsObjectHashtable lBFSTable(nullptr, nullptr, DeleteBFSEntry, nullptr);
     mAdjacencyList.Enumerate(InitBFSTable, &lBFSTable);
     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;
     nsCStringKey *source = new nsCStringKey(fromC.get());
     BFSTableData *data = (BFSTableData*)lBFSTable.Get(source);
     if (!data) {
         delete source;
         return NS_ERROR_FAILURE;
     }
     data->color = gray;
     data->distance = 0;
     CStreamConvDeallocator *dtorFunc = new CStreamConvDeallocator();
     nsDeque grayQ(dtorFunc);
     // Now generate the shortest path tree.
     grayQ.Push(source);
     while (0 < grayQ.GetSize()) {
         nsCStringKey *currentHead = (nsCStringKey*)grayQ.PeekFront();
         SCTableData *data2 = (SCTableData*)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 = (BFSTableData*)lBFSTable.Get(currentHead);
         if (!headVertexState) return NS_ERROR_FAILURE;
         int32_t edgeCount = data2->Count();
         for (int32_t i = 0; i < edgeCount; i++) {
             nsIAtom* curVertexAtom = data2->ObjectAt(i);
             nsAutoString curVertexStr;
             curVertexAtom->ToString(curVertexStr);
             nsCStringKey *curVertex = new nsCStringKey(ToNewCString(curVertexStr),
                                         curVertexStr.Length(), nsCStringKey::OWN);
             BFSTableData *curVertexState = (BFSTableData*)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 = (nsCStringKey*)currentHead->Clone();
                 if (!curVertexState->predecessor) {
                     delete curVertex;
                     return NS_ERROR_OUT_OF_MEMORY;
                 }
                 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;
         nsCStringKey *cur = (nsCStringKey*)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, toStr;
     rv = ParseFromTo(aContractID, fromStr, toStr);
     if (NS_FAILED(rv)) return rv;
     // get the root CONTRACTID
     nsAutoCString ContractIDPrefix(NS_ISTREAMCONVERTER_KEY);
     nsTArray<nsCString> *shortestPath = new nsTArray<nsCString>();
     nsCStringKey toMIMEType(toStr);
     data = (BFSTableData*)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) {
         nsCStringKey *key = data->key;
         if (fromStr.Equals(key->GetString())) {
             // 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 = (BFSTableData*)lBFSTable.Get(data->predecessor);
         if (!predecessorData) break; // no predecessor, chain doesn't exist.
         // build out the CONTRACTID.
         nsAutoCString newContractID(ContractIDPrefix);
         newContractID.AppendLiteral("?from=");
         nsCStringKey *predecessorKey = predecessorData->key;
         newContractID.Append(predecessorKey->GetString());
         newContractID.AppendLiteral("&to=");
         newContractID.Append(key->GetString());
         // Add this CONTRACTID to the chain.
         rv = shortestPath->AppendElement(newContractID) ? NS_OK : NS_ERROR_FAILURE;  // XXX this method incorrectly returns a bool
         NS_ASSERTION(NS_SUCCEEDED(rv), "AppendElement failed");
         // 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::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;
         *_retval = convertedData;
         NS_ADDREF(*_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;
             }
             nsCOMPtr<nsIStreamListener> chainListener(do_QueryInterface(converter, &rv));
             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 = chainListener;
         }
         delete converterChain;
         // return the first listener in the chain.
         *_retval = finalListener;
         NS_ADDREF(*_retval);
     } else {
         // we're going direct.
         *_retval = listener;
         NS_ADDREF(*_retval);
         rv = listener->AsyncConvertData(aFromType, aToType, aListener, aContext);
     }
     return rv;
 }
 nsresult
 NS_NewStreamConv(nsStreamConverterService** aStreamConv)
 {
     NS_PRECONDITION(aStreamConv != nullptr, "null ptr");
     if (!aStreamConv) return NS_ERROR_NULL_POINTER;
     *aStreamConv = new nsStreamConverterService();
     NS_ADDREF(*aStreamConv);
     return NS_OK;
 }

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netwerk/streamconv/src/nsStreamConverterService.cpp@b8a032363ba2 (annotated)

netwerk/streamconv/src/nsStreamConverterService.cpp