Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1075 insertions, 0 deletions

diff --git a/parser/htmlparser/nsParser.cpp b/parser/htmlparser/nsParser.cpp
new file mode 100644
index 0000000000..04d02e2084
--- /dev/null
+++ b/parser/htmlparser/nsParser.cpp
@@ -0,0 +1,1075 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=2 et tw=80: */
+/* 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 "nsAtom.h"
+#include "nsParser.h"
+#include "nsString.h"
+#include "nsCRT.h"
+#include "nsScanner.h"
+#include "plstr.h"
+#include "nsIChannel.h"
+#include "nsIInputStream.h"
+#include "CNavDTD.h"
+#include "prenv.h"
+#include "prlock.h"
+#include "prcvar.h"
+#include "nsReadableUtils.h"
+#include "nsCOMPtr.h"
+#include "nsExpatDriver.h"
+#include "nsIFragmentContentSink.h"
+#include "nsStreamUtils.h"
+#include "nsXPCOMCIDInternal.h"
+#include "nsMimeTypes.h"
+#include "nsCharsetSource.h"
+#include "nsThreadUtils.h"
+#include "nsIHTMLContentSink.h"
+
+#include "mozilla/BinarySearch.h"
+#include "mozilla/CondVar.h"
+#include "mozilla/dom/ScriptLoader.h"
+#include "mozilla/Encoding.h"
+#include "mozilla/Mutex.h"
+
+using namespace mozilla;
+
+#define NS_PARSER_FLAG_PENDING_CONTINUE_EVENT 0x00000001
+#define NS_PARSER_FLAG_CAN_TOKENIZE 0x00000002
+
+//-------------- Begin ParseContinue Event Definition ------------------------
+/*
+The parser can be explicitly interrupted by passing a return value of
+NS_ERROR_HTMLPARSER_INTERRUPTED from BuildModel on the DTD. This will cause
+the parser to stop processing and allow the application to return to the event
+loop. The data which was left at the time of interruption will be processed
+the next time OnDataAvailable is called. If the parser has received its final
+chunk of data then OnDataAvailable will no longer be called by the networking
+module, so the parser will schedule a nsParserContinueEvent which will call
+the parser to process the remaining data after returning to the event loop.
+If the parser is interrupted while processing the remaining data it will
+schedule another ParseContinueEvent. The processing of data followed by
+scheduling of the continue events will proceed until either:
+
+  1) All of the remaining data can be processed without interrupting
+  2) The parser has been cancelled.
+
+
+This capability is currently used in CNavDTD and nsHTMLContentSink. The
+nsHTMLContentSink is notified by CNavDTD when a chunk of tokens is going to be
+processed and when each token is processed. The nsHTML content sink records
+the time when the chunk has started processing and will return
+NS_ERROR_HTMLPARSER_INTERRUPTED if the token processing time has exceeded a
+threshold called max tokenizing processing time. This allows the content sink
+to limit how much data is processed in a single chunk which in turn gates how
+much time is spent away from the event loop. Processing smaller chunks of data
+also reduces the time spent in subsequent reflows.
+
+This capability is most apparent when loading large documents. If the maximum
+token processing time is set small enough the application will remain
+responsive during document load.
+
+A side-effect of this capability is that document load is not complete when
+the last chunk of data is passed to OnDataAvailable since  the parser may have
+been interrupted when the last chunk of data arrived. The document is complete
+when all of the document has been tokenized and there aren't any pending
+nsParserContinueEvents. This can cause problems if the application assumes
+that it can monitor the load requests to determine when the document load has
+been completed. This is what happens in Mozilla. The document is considered
+completely loaded when all of the load requests have been satisfied. To delay
+the document load until all of the parsing has been completed the
+nsHTMLContentSink adds a dummy parser load request which is not removed until
+the nsHTMLContentSink's DidBuildModel is called. The CNavDTD will not call
+DidBuildModel until the final chunk of data has been passed to the parser
+through the OnDataAvailable and there aren't any pending
+nsParserContineEvents.
+
+Currently the parser is ignores requests to be interrupted during the
+processing of script.  This is because a document.write followed by JavaScript
+calls to manipulate the DOM may fail if the parser was interrupted during the
+document.write.
+
+For more details @see bugzilla bug 76722
+*/
+
+class nsParserContinueEvent : public Runnable {
+ public:
+  RefPtr<nsParser> mParser;
+
+  explicit nsParserContinueEvent(nsParser* aParser)
+      : mozilla::Runnable("nsParserContinueEvent"), mParser(aParser) {}
+
+  NS_IMETHOD Run() override {
+    mParser->HandleParserContinueEvent(this);
+    return NS_OK;
+  }
+};
+
+//-------------- End ParseContinue Event Definition ------------------------
+
+/**
+ *  default constructor
+ */
+nsParser::nsParser() : mCharset(WINDOWS_1252_ENCODING) { Initialize(); }
+
+nsParser::~nsParser() { Cleanup(); }
+
+void nsParser::Initialize() {
+  mContinueEvent = nullptr;
+  mCharsetSource = kCharsetUninitialized;
+  mCharset = WINDOWS_1252_ENCODING;
+  mInternalState = NS_OK;
+  mStreamStatus = NS_OK;
+  mCommand = eViewNormal;
+  mBlocked = 0;
+  mFlags = NS_PARSER_FLAG_CAN_TOKENIZE;
+
+  mProcessingNetworkData = false;
+  mIsAboutBlank = false;
+}
+
+void nsParser::Cleanup() {
+  // It should not be possible for this flag to be set when we are getting
+  // destroyed since this flag implies a pending nsParserContinueEvent, which
+  // has an owning reference to |this|.
+  NS_ASSERTION(!(mFlags & NS_PARSER_FLAG_PENDING_CONTINUE_EVENT), "bad");
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsParser)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsParser)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mDTD)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSink)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsParser)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDTD)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSink)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsParser)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsParser)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsParser)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+  NS_INTERFACE_MAP_ENTRY(nsIParser)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIParser)
+NS_INTERFACE_MAP_END
+
+// The parser continue event is posted only if
+// all of the data to parse has been passed to ::OnDataAvailable
+// and the parser has been interrupted by the content sink
+// because the processing of tokens took too long.
+
+nsresult nsParser::PostContinueEvent() {
+  if (!(mFlags & NS_PARSER_FLAG_PENDING_CONTINUE_EVENT)) {
+    // If this flag isn't set, then there shouldn't be a live continue event!
+    NS_ASSERTION(!mContinueEvent, "bad");
+
+    // This creates a reference cycle between this and the event that is
+    // broken when the event fires.
+    nsCOMPtr<nsIRunnable> event = new nsParserContinueEvent(this);
+    if (NS_FAILED(NS_DispatchToCurrentThread(event))) {
+      NS_WARNING("failed to dispatch parser continuation event");
+    } else {
+      mFlags |= NS_PARSER_FLAG_PENDING_CONTINUE_EVENT;
+      mContinueEvent = event;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(void)
+nsParser::GetCommand(nsCString& aCommand) { aCommand = mCommandStr; }
+
+/**
+ *  Call this method once you've created a parser, and want to instruct it
+ *  about the command which caused the parser to be constructed. For example,
+ *  this allows us to select a DTD which can do, say, view-source.
+ *
+ *  @param   aCommand the command string to set
+ */
+NS_IMETHODIMP_(void)
+nsParser::SetCommand(const char* aCommand) {
+  mCommandStr.Assign(aCommand);
+  if (mCommandStr.EqualsLiteral("view-source")) {
+    mCommand = eViewSource;
+  } else if (mCommandStr.EqualsLiteral("view-fragment")) {
+    mCommand = eViewFragment;
+  } else {
+    mCommand = eViewNormal;
+  }
+}
+
+/**
+ *  Call this method once you've created a parser, and want to instruct it
+ *  about the command which caused the parser to be constructed. For example,
+ *  this allows us to select a DTD which can do, say, view-source.
+ *
+ *  @param   aParserCommand the command to set
+ */
+NS_IMETHODIMP_(void)
+nsParser::SetCommand(eParserCommands aParserCommand) {
+  mCommand = aParserCommand;
+}
+
+/**
+ *  Call this method once you've created a parser, and want to instruct it
+ *  about what charset to load
+ *
+ *  @param   aCharset- the charset of a document
+ *  @param   aCharsetSource- the source of the charset
+ */
+void nsParser::SetDocumentCharset(NotNull<const Encoding*> aCharset,
+                                  int32_t aCharsetSource,
+                                  bool aForceAutoDetection) {
+  mCharset = aCharset;
+  mCharsetSource = aCharsetSource;
+  if (mParserContext) {
+    mParserContext->mScanner.SetDocumentCharset(aCharset, aCharsetSource);
+  }
+}
+
+void nsParser::SetSinkCharset(NotNull<const Encoding*> aCharset) {
+  if (mSink) {
+    mSink->SetDocumentCharset(aCharset);
+  }
+}
+
+/**
+ *  This method gets called in order to set the content
+ *  sink for this parser to dump nodes to.
+ *
+ *  @param   nsIContentSink interface for node receiver
+ */
+NS_IMETHODIMP_(void)
+nsParser::SetContentSink(nsIContentSink* aSink) {
+  MOZ_ASSERT(aSink, "sink cannot be null!");
+  mSink = aSink;
+
+  if (mSink) {
+    mSink->SetParser(this);
+    nsCOMPtr<nsIHTMLContentSink> htmlSink = do_QueryInterface(mSink);
+    if (htmlSink) {
+      mIsAboutBlank = true;
+    }
+  }
+}
+
+/**
+ * retrieve the sink set into the parser
+ * @return  current sink
+ */
+NS_IMETHODIMP_(nsIContentSink*)
+nsParser::GetContentSink() { return mSink; }
+
+////////////////////////////////////////////////////////////////////////
+
+/**
+ * This gets called just prior to the model actually
+ * being constructed. It's important to make this the
+ * last thing that happens right before parsing, so we
+ * can delay until the last moment the resolution of
+ * which DTD to use (unless of course we're assigned one).
+ */
+nsresult nsParser::WillBuildModel() {
+  if (!mParserContext) return NS_ERROR_HTMLPARSER_INVALIDPARSERCONTEXT;
+
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  if (eUnknownDetect != mParserContext->mAutoDetectStatus) return NS_OK;
+
+  if (eDTDMode_autodetect == mParserContext->mDTDMode) {
+    if (mIsAboutBlank) {
+      mParserContext->mDTDMode = eDTDMode_quirks;
+      mParserContext->mDocType = eHTML_Quirks;
+    } else {
+      mParserContext->mDTDMode = eDTDMode_full_standards;
+      mParserContext->mDocType = eXML;
+    }
+  }  // else XML fragment with nested parser context
+
+  // We always find a DTD.
+  mParserContext->mAutoDetectStatus = ePrimaryDetect;
+
+  // Quick check for view source.
+  MOZ_ASSERT(mParserContext->mParserCommand != eViewSource,
+             "The old parser is not supposed to be used for View Source "
+             "anymore.");
+
+  // Now see if we're parsing XML or HTML (which, as far as we're concerned,
+  // simply means "not XML").
+  if (mParserContext->mDocType == eXML) {
+    RefPtr<nsExpatDriver> expat = new nsExpatDriver();
+    nsresult rv = expat->Initialize(mParserContext->mScanner.GetURI(), mSink);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    mDTD = expat.forget();
+  } else {
+    mDTD = new CNavDTD();
+  }
+
+  return mSink->WillBuildModel(mParserContext->mDTDMode);
+}
+
+/**
+ * This gets called when the parser is done with its input.
+ */
+void nsParser::DidBuildModel() {
+  if (IsComplete() && mParserContext) {
+    // Let sink know if we're about to end load because we've been terminated.
+    // In that case we don't want it to run deferred scripts.
+    bool terminated = mInternalState == NS_ERROR_HTMLPARSER_STOPPARSING;
+    if (mDTD && mSink) {
+      mDTD->DidBuildModel();
+      mSink->DidBuildModel(terminated);
+    }
+
+    // Ref. to bug 61462.
+    mParserContext->mRequest = nullptr;
+  }
+}
+
+/**
+ *  Call this when you want to *force* the parser to terminate the
+ *  parsing process altogether. This is binary -- so once you terminate
+ *  you can't resume without restarting altogether.
+ */
+NS_IMETHODIMP
+nsParser::Terminate(void) {
+  // We should only call DidBuildModel once, so don't do anything if this is
+  // the second time that Terminate has been called.
+  if (mInternalState == NS_ERROR_HTMLPARSER_STOPPARSING) {
+    return NS_OK;
+  }
+
+  nsresult result = NS_OK;
+  // XXX - [ until we figure out a way to break parser-sink circularity ]
+  // Hack - Hold a reference until we are completely done...
+  nsCOMPtr<nsIParser> kungFuDeathGrip(this);
+  mInternalState = result = NS_ERROR_HTMLPARSER_STOPPARSING;
+
+  // @see bug 108049
+  // If NS_PARSER_FLAG_PENDING_CONTINUE_EVENT is set then reset it so
+  // DidBuildModel will call DidBuildModel on the DTD. Note: The IsComplete()
+  // call inside of DidBuildModel looks at the pendingContinueEvents flag.
+  if (mFlags & NS_PARSER_FLAG_PENDING_CONTINUE_EVENT) {
+    NS_ASSERTION(mContinueEvent, "mContinueEvent is null");
+    // Revoke the pending continue parsing event
+    mContinueEvent = nullptr;
+    mFlags &= ~NS_PARSER_FLAG_PENDING_CONTINUE_EVENT;
+  }
+
+  if (mDTD) {
+    mDTD->Terminate();
+    DidBuildModel();
+  } else if (mSink) {
+    // We have no parser context or no DTD yet (so we got terminated before we
+    // got any data).  Manually break the reference cycle with the sink.
+    result = mSink->DidBuildModel(true);
+    NS_ENSURE_SUCCESS(result, result);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsParser::ContinueInterruptedParsing() {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  // If there are scripts executing, then the content sink is jumping the gun
+  // (probably due to a synchronous XMLHttpRequest) and will re-enable us
+  // later, see bug 460706.
+  if (!IsOkToProcessNetworkData()) {
+    return NS_OK;
+  }
+
+  // If the stream has already finished, there's a good chance
+  // that we might start closing things down when the parser
+  // is reenabled. To make sure that we're not deleted across
+  // the reenabling process, hold a reference to ourselves.
+  nsresult result = NS_OK;
+  nsCOMPtr<nsIParser> kungFuDeathGrip(this);
+  nsCOMPtr<nsIContentSink> sinkDeathGrip(mSink);
+
+#ifdef DEBUG
+  if (mBlocked) {
+    NS_WARNING("Don't call ContinueInterruptedParsing on a blocked parser.");
+  }
+#endif
+
+  bool isFinalChunk =
+      mParserContext && mParserContext->mStreamListenerState == eOnStop;
+
+  mProcessingNetworkData = true;
+  if (sinkDeathGrip) {
+    sinkDeathGrip->WillParse();
+  }
+  result = ResumeParse(true, isFinalChunk);  // Ref. bug 57999
+  mProcessingNetworkData = false;
+
+  if (result != NS_OK) {
+    result = mInternalState;
+  }
+
+  return result;
+}
+
+/**
+ *  Stops parsing temporarily. That is, it will prevent the
+ *  parser from building up content model while scripts
+ *  are being loaded (either an external script from a web
+ *  page, or any number of extension content scripts).
+ */
+NS_IMETHODIMP_(void)
+nsParser::BlockParser() { mBlocked++; }
+
+/**
+ *  Open up the parser for tokenization, building up content
+ *  model..etc. However, this method does not resume parsing
+ *  automatically. It's the callers' responsibility to restart
+ *  the parsing engine.
+ */
+NS_IMETHODIMP_(void)
+nsParser::UnblockParser() {
+  MOZ_DIAGNOSTIC_ASSERT(mBlocked > 0);
+  if (MOZ_LIKELY(mBlocked > 0)) {
+    mBlocked--;
+  }
+}
+
+NS_IMETHODIMP_(void)
+nsParser::ContinueInterruptedParsingAsync() {
+  MOZ_ASSERT(mSink);
+  if (MOZ_LIKELY(mSink)) {
+    mSink->ContinueInterruptedParsingAsync();
+  }
+}
+
+/**
+ * Call this to query whether the parser is enabled or not.
+ */
+NS_IMETHODIMP_(bool)
+nsParser::IsParserEnabled() { return !mBlocked; }
+
+/**
+ * Call this to query whether the parser thinks it's done with parsing.
+ */
+NS_IMETHODIMP_(bool)
+nsParser::IsComplete() {
+  return !(mFlags & NS_PARSER_FLAG_PENDING_CONTINUE_EVENT);
+}
+
+void nsParser::HandleParserContinueEvent(nsParserContinueEvent* ev) {
+  // Ignore any revoked continue events...
+  if (mContinueEvent != ev) return;
+
+  mFlags &= ~NS_PARSER_FLAG_PENDING_CONTINUE_EVENT;
+  mContinueEvent = nullptr;
+
+  NS_ASSERTION(IsOkToProcessNetworkData(),
+               "Interrupted in the middle of a script?");
+  ContinueInterruptedParsing();
+}
+
+bool nsParser::IsInsertionPointDefined() { return false; }
+
+void nsParser::IncrementScriptNestingLevel() {}
+
+void nsParser::DecrementScriptNestingLevel() {}
+
+bool nsParser::HasNonzeroScriptNestingLevel() const { return false; }
+
+bool nsParser::IsScriptCreated() { return false; }
+
+/**
+ *  This is the main controlling routine in the parsing process.
+ *  Note that it may get called multiple times for the same scanner,
+ *  since this is a pushed based system, and all the tokens may
+ *  not have been consumed by the scanner during a given invocation
+ *  of this method.
+ */
+NS_IMETHODIMP
+nsParser::Parse(nsIURI* aURL) {
+  MOZ_ASSERT(aURL, "Error: Null URL given");
+
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  if (!aURL) {
+    return NS_ERROR_HTMLPARSER_BADURL;
+  }
+
+  MOZ_ASSERT(!mParserContext, "We expect mParserContext to be null.");
+
+  mParserContext = MakeUnique<CParserContext>(aURL, mCommand);
+
+  return NS_OK;
+}
+
+/**
+ * Used by XML fragment parsing below.
+ *
+ * @param   aSourceBuffer contains a string-full of real content
+ */
+nsresult nsParser::Parse(const nsAString& aSourceBuffer, bool aLastCall) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  // Don't bother if we're never going to parse this.
+  if (mInternalState == NS_ERROR_HTMLPARSER_STOPPARSING) {
+    return NS_OK;
+  }
+
+  if (!aLastCall && aSourceBuffer.IsEmpty()) {
+    // Nothing is being passed to the parser so return
+    // immediately. mUnusedInput will get processed when
+    // some data is actually passed in.
+    // But if this is the last call, make sure to finish up
+    // stuff correctly.
+    return NS_OK;
+  }
+
+  // Maintain a reference to ourselves so we don't go away
+  // till we're completely done.
+  nsCOMPtr<nsIParser> kungFuDeathGrip(this);
+
+  if (!mParserContext) {
+    // Only make a new context if we don't have one.
+    mParserContext =
+        MakeUnique<CParserContext>(mUnusedInput, mCommand, aLastCall);
+
+    mUnusedInput.Truncate();
+  } else if (aLastCall) {
+    // Set stream listener state to eOnStop, on the final context - Fix
+    // 68160, to guarantee DidBuildModel() call - Fix 36148
+    mParserContext->mStreamListenerState = eOnStop;
+    mParserContext->mScanner.SetIncremental(false);
+  }
+
+  mParserContext->mScanner.Append(aSourceBuffer);
+  return ResumeParse(false, false, false);
+}
+
+nsresult nsParser::ParseFragment(const nsAString& aSourceBuffer,
+                                 nsTArray<nsString>& aTagStack) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  nsresult result = NS_OK;
+  nsAutoString theContext;
+  uint32_t theCount = aTagStack.Length();
+  uint32_t theIndex = 0;
+
+  for (theIndex = 0; theIndex < theCount; theIndex++) {
+    theContext.Append('<');
+    theContext.Append(aTagStack[theCount - theIndex - 1]);
+    theContext.Append('>');
+  }
+
+  if (theCount == 0) {
+    // Ensure that the buffer is not empty. Because none of the DTDs care
+    // about leading whitespace, this doesn't change the result.
+    theContext.Assign(' ');
+  }
+
+  // First, parse the context to build up the DTD's tag stack. Note that we
+  // pass false for the aLastCall parameter.
+  result = Parse(theContext, false);
+  if (NS_FAILED(result)) {
+    return result;
+  }
+
+  if (!mSink) {
+    // Parse must have failed in the XML case and so the sink was killed.
+    return NS_ERROR_HTMLPARSER_STOPPARSING;
+  }
+
+  nsCOMPtr<nsIFragmentContentSink> fragSink = do_QueryInterface(mSink);
+  NS_ASSERTION(fragSink, "ParseFragment requires a fragment content sink");
+
+  fragSink->WillBuildContent();
+  // Now, parse the actual content. Note that this is the last call
+  // for HTML content, but for XML, we will want to build and parse
+  // the end tags.  However, if tagStack is empty, it's the last call
+  // for XML as well.
+  if (theCount == 0) {
+    result = Parse(aSourceBuffer, true);
+    fragSink->DidBuildContent();
+  } else {
+    // Add an end tag chunk, so expat will read the whole source buffer,
+    // and not worry about ']]' etc.
+    result = Parse(aSourceBuffer + u"</"_ns, false);
+    fragSink->DidBuildContent();
+
+    if (NS_SUCCEEDED(result)) {
+      nsAutoString endContext;
+      for (theIndex = 0; theIndex < theCount; theIndex++) {
+        // we already added an end tag chunk above
+        if (theIndex > 0) {
+          endContext.AppendLiteral("</");
+        }
+
+        nsString& thisTag = aTagStack[theIndex];
+        // was there an xmlns=?
+        int32_t endOfTag = thisTag.FindChar(char16_t(' '));
+        if (endOfTag == -1) {
+          endContext.Append(thisTag);
+        } else {
+          endContext.Append(Substring(thisTag, 0, endOfTag));
+        }
+
+        endContext.Append('>');
+      }
+
+      result = Parse(endContext, true);
+    }
+  }
+
+  mParserContext.reset();
+
+  return result;
+}
+
+/**
+ *  This routine is called to cause the parser to continue parsing its
+ *  underlying stream.  This call allows the parse process to happen in
+ *  chunks, such as when the content is push based, and we need to parse in
+ *  pieces.
+ *
+ *  An interesting change in how the parser gets used has led us to add extra
+ *  processing to this method.  The case occurs when the parser is blocked in
+ *  one context, and gets a parse(string) call in another context.  In this
+ *  case, the parserContexts are linked. No problem.
+ *
+ *  The problem is that Parse(string) assumes that it can proceed unabated,
+ *  but if the parser is already blocked that assumption is false. So we
+ *  needed to add a mechanism here to allow the parser to continue to process
+ *  (the pop and free) contexts until 1) it get's blocked again; 2) it runs
+ *  out of contexts.
+ *
+ *
+ *  @param   allowItertion : set to true if non-script resumption is requested
+ *  @param   aIsFinalChunk : tells us when the last chunk of data is provided.
+ *  @return  error code -- 0 if ok, non-zero if error.
+ */
+nsresult nsParser::ResumeParse(bool allowIteration, bool aIsFinalChunk,
+                               bool aCanInterrupt) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  nsresult result = NS_OK;
+
+  if (!mBlocked && mInternalState != NS_ERROR_HTMLPARSER_STOPPARSING) {
+    result = WillBuildModel();
+    if (NS_FAILED(result)) {
+      mFlags &= ~NS_PARSER_FLAG_CAN_TOKENIZE;
+      return result;
+    }
+
+    if (mDTD) {
+      mSink->WillResume();
+      bool theIterationIsOk = true;
+
+      while (result == NS_OK && theIterationIsOk) {
+        if (!mUnusedInput.IsEmpty()) {
+          // -- Ref: Bug# 22485 --
+          // Insert the unused input into the source buffer
+          // as if it was read from the input stream.
+          // Adding UngetReadable() per vidur!!
+          mParserContext->mScanner.UngetReadable(mUnusedInput);
+          mUnusedInput.Truncate(0);
+        }
+
+        // Only allow parsing to be interrupted in the subsequent call to
+        // build model.
+        nsresult theTokenizerResult;
+        if (mFlags & NS_PARSER_FLAG_CAN_TOKENIZE) {
+          mParserContext->mScanner.Mark();
+          if (mParserContext->mDocType == eXML &&
+              mParserContext->mParserCommand != eViewSource) {
+            nsExpatDriver* expat = static_cast<nsExpatDriver*>(mDTD.get());
+            theTokenizerResult =
+                expat->ResumeParse(mParserContext->mScanner, aIsFinalChunk);
+            if (NS_FAILED(theTokenizerResult)) {
+              mParserContext->mScanner.RewindToMark();
+              if (NS_ERROR_HTMLPARSER_STOPPARSING == theTokenizerResult) {
+                theTokenizerResult = Terminate();
+                mSink = nullptr;
+              }
+            }
+          } else {
+            // Nothing to do for non-XML. Note that this should only be
+            // about:blank at this point, we're also checking for view-source
+            // above, but that shouldn't end up here anymore.
+            theTokenizerResult = NS_ERROR_HTMLPARSER_EOF;
+          }
+        } else {
+          theTokenizerResult = NS_OK;
+        }
+
+        result = mDTD->BuildModel(mSink);
+        if (result == NS_ERROR_HTMLPARSER_INTERRUPTED && aIsFinalChunk) {
+          PostContinueEvent();
+        }
+
+        theIterationIsOk = theTokenizerResult != NS_ERROR_HTMLPARSER_EOF &&
+                           result != NS_ERROR_HTMLPARSER_INTERRUPTED;
+
+        // Make sure not to stop parsing too early. Therefore, before shutting
+        // down the parser, it's important to check whether the input buffer
+        // has been scanned to completion (theTokenizerResult should be kEOF).
+        // kEOF -> End of buffer.
+
+        // If we're told the parser has been blocked, we disable all further
+        // parsing (and cache any data coming in) until the parser is
+        // re-enabled.
+        if (NS_ERROR_HTMLPARSER_BLOCK == result) {
+          mSink->WillInterrupt();
+          return NS_OK;
+        }
+        if (NS_ERROR_HTMLPARSER_STOPPARSING == result) {
+          // Note: Parser Terminate() calls DidBuildModel.
+          if (mInternalState != NS_ERROR_HTMLPARSER_STOPPARSING) {
+            DidBuildModel();
+            mInternalState = result;
+          }
+
+          return NS_OK;
+        }
+        if (((NS_OK == result &&
+              theTokenizerResult == NS_ERROR_HTMLPARSER_EOF) ||
+             result == NS_ERROR_HTMLPARSER_INTERRUPTED) &&
+            mParserContext->mStreamListenerState == eOnStop) {
+          DidBuildModel();
+          return NS_OK;
+        }
+
+        if (theTokenizerResult == NS_ERROR_HTMLPARSER_EOF ||
+            result == NS_ERROR_HTMLPARSER_INTERRUPTED) {
+          result = (result == NS_ERROR_HTMLPARSER_INTERRUPTED) ? NS_OK : result;
+          mSink->WillInterrupt();
+        }
+      }
+    } else {
+      mInternalState = result = NS_ERROR_HTMLPARSER_UNRESOLVEDDTD;
+    }
+  }
+
+  return (result == NS_ERROR_HTMLPARSER_INTERRUPTED) ? NS_OK : result;
+}
+
+/*******************************************************************
+  These methods are used to talk to the netlib system...
+ *******************************************************************/
+
+nsresult nsParser::OnStartRequest(nsIRequest* request) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  MOZ_ASSERT(eNone == mParserContext->mStreamListenerState,
+             "Parser's nsIStreamListener API was not setup "
+             "correctly in constructor.");
+
+  mParserContext->mStreamListenerState = eOnStart;
+  mParserContext->mAutoDetectStatus = eUnknownDetect;
+  mParserContext->mRequest = request;
+
+  mDTD = nullptr;
+
+  nsresult rv;
+  nsAutoCString contentType;
+  nsCOMPtr<nsIChannel> channel = do_QueryInterface(request);
+  if (channel) {
+    rv = channel->GetContentType(contentType);
+    if (NS_SUCCEEDED(rv)) {
+      mParserContext->SetMimeType(contentType);
+    }
+  }
+
+  rv = NS_OK;
+
+  return rv;
+}
+
+static bool ExtractCharsetFromXmlDeclaration(const unsigned char* aBytes,
+                                             int32_t aLen,
+                                             nsCString& oCharset) {
+  // This code is rather pointless to have. Might as well reuse expat as
+  // seen in nsHtml5StreamParser. -- hsivonen
+  oCharset.Truncate();
+  if ((aLen >= 5) && ('<' == aBytes[0]) && ('?' == aBytes[1]) &&
+      ('x' == aBytes[2]) && ('m' == aBytes[3]) && ('l' == aBytes[4])) {
+    int32_t i;
+    bool versionFound = false, encodingFound = false;
+    for (i = 6; i < aLen && !encodingFound; ++i) {
+      // end of XML declaration?
+      if ((((char*)aBytes)[i] == '?') && ((i + 1) < aLen) &&
+          (((char*)aBytes)[i + 1] == '>')) {
+        break;
+      }
+      // Version is required.
+      if (!versionFound) {
+        // Want to avoid string comparisons, hence looking for 'n'
+        // and only if found check the string leading to it. Not
+        // foolproof, but fast.
+        // The shortest string allowed before this is  (strlen==13):
+        // <?xml version
+        if ((((char*)aBytes)[i] == 'n') && (i >= 12) &&
+            (0 == strncmp("versio", (char*)(aBytes + i - 6), 6))) {
+          // Fast forward through version
+          char q = 0;
+          for (++i; i < aLen; ++i) {
+            char qi = ((char*)aBytes)[i];
+            if (qi == '\'' || qi == '"') {
+              if (q && q == qi) {
+                //  ending quote
+                versionFound = true;
+                break;
+              } else {
+                // Starting quote
+                q = qi;
+              }
+            }
+          }
+        }
+      } else {
+        // encoding must follow version
+        // Want to avoid string comparisons, hence looking for 'g'
+        // and only if found check the string leading to it. Not
+        // foolproof, but fast.
+        // The shortest allowed string before this (strlen==26):
+        // <?xml version="1" encoding
+        if ((((char*)aBytes)[i] == 'g') && (i >= 25) &&
+            (0 == strncmp("encodin", (char*)(aBytes + i - 7), 7))) {
+          int32_t encStart = 0;
+          char q = 0;
+          for (++i; i < aLen; ++i) {
+            char qi = ((char*)aBytes)[i];
+            if (qi == '\'' || qi == '"') {
+              if (q && q == qi) {
+                int32_t count = i - encStart;
+                // encoding value is invalid if it is UTF-16
+                if (count > 0 &&
+                    PL_strncasecmp("UTF-16", (char*)(aBytes + encStart),
+                                   count)) {
+                  oCharset.Assign((char*)(aBytes + encStart), count);
+                }
+                encodingFound = true;
+                break;
+              } else {
+                encStart = i + 1;
+                q = qi;
+              }
+            }
+          }
+        }
+      }  // if (!versionFound)
+    }    // for
+  }
+  return !oCharset.IsEmpty();
+}
+
+inline char GetNextChar(nsACString::const_iterator& aStart,
+                        nsACString::const_iterator& aEnd) {
+  NS_ASSERTION(aStart != aEnd, "end of buffer");
+  return (++aStart != aEnd) ? *aStart : '\0';
+}
+
+static nsresult NoOpParserWriteFunc(nsIInputStream* in, void* closure,
+                                    const char* fromRawSegment,
+                                    uint32_t toOffset, uint32_t count,
+                                    uint32_t* writeCount) {
+  *writeCount = count;
+  return NS_OK;
+}
+
+typedef struct {
+  bool mNeedCharsetCheck;
+  nsParser* mParser;
+  nsScanner* mScanner;
+  nsIRequest* mRequest;
+} ParserWriteStruct;
+
+/*
+ * This function is invoked as a result of a call to a stream's
+ * ReadSegments() method. It is called for each contiguous buffer
+ * of data in the underlying stream or pipe. Using ReadSegments
+ * allows us to avoid copying data to read out of the stream.
+ */
+static nsresult ParserWriteFunc(nsIInputStream* in, void* closure,
+                                const char* fromRawSegment, uint32_t toOffset,
+                                uint32_t count, uint32_t* writeCount) {
+  nsresult result;
+  ParserWriteStruct* pws = static_cast<ParserWriteStruct*>(closure);
+  const unsigned char* buf =
+      reinterpret_cast<const unsigned char*>(fromRawSegment);
+  uint32_t theNumRead = count;
+
+  if (!pws) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (pws->mNeedCharsetCheck) {
+    pws->mNeedCharsetCheck = false;
+    int32_t source;
+    auto preferred = pws->mParser->GetDocumentCharset(source);
+
+    // This code was bogus when I found it. It expects the BOM or the XML
+    // declaration to be entirely in the first network buffer. -- hsivonen
+    const Encoding* encoding;
+    std::tie(encoding, std::ignore) = Encoding::ForBOM(Span(buf, count));
+    if (encoding) {
+      // The decoder will swallow the BOM. The UTF-16 will re-sniff for
+      // endianness. The value of preferred is now "UTF-8", "UTF-16LE"
+      // or "UTF-16BE".
+      preferred = WrapNotNull(encoding);
+      source = kCharsetFromByteOrderMark;
+    } else if (source < kCharsetFromChannel) {
+      nsAutoCString declCharset;
+
+      if (ExtractCharsetFromXmlDeclaration(buf, count, declCharset)) {
+        encoding = Encoding::ForLabel(declCharset);
+        if (encoding) {
+          preferred = WrapNotNull(encoding);
+          source = kCharsetFromMetaTag;
+        }
+      }
+    }
+
+    pws->mParser->SetDocumentCharset(preferred, source, false);
+    pws->mParser->SetSinkCharset(preferred);
+  }
+
+  result = pws->mScanner->Append(fromRawSegment, theNumRead);
+  if (NS_SUCCEEDED(result)) {
+    *writeCount = count;
+  }
+
+  return result;
+}
+
+nsresult nsParser::OnDataAvailable(nsIRequest* request,
+                                   nsIInputStream* pIStream,
+                                   uint64_t sourceOffset, uint32_t aLength) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  MOZ_ASSERT((eOnStart == mParserContext->mStreamListenerState ||
+              eOnDataAvail == mParserContext->mStreamListenerState),
+             "Error: OnStartRequest() must be called before OnDataAvailable()");
+  MOZ_ASSERT(NS_InputStreamIsBuffered(pIStream),
+             "Must have a buffered input stream");
+
+  nsresult rv = NS_OK;
+
+  if (mIsAboutBlank) {
+    MOZ_ASSERT(false, "Must not get OnDataAvailable for about:blank");
+    // ... but if an extension tries to feed us data for about:blank in a
+    // release build, silently ignore the data.
+    uint32_t totalRead;
+    rv = pIStream->ReadSegments(NoOpParserWriteFunc, nullptr, aLength,
+                                &totalRead);
+    return rv;
+  }
+
+  if (mParserContext->mRequest == request) {
+    mParserContext->mStreamListenerState = eOnDataAvail;
+
+    uint32_t totalRead;
+    ParserWriteStruct pws;
+    pws.mNeedCharsetCheck = true;
+    pws.mParser = this;
+    pws.mScanner = &mParserContext->mScanner;
+    pws.mRequest = request;
+
+    rv = pIStream->ReadSegments(ParserWriteFunc, &pws, aLength, &totalRead);
+    if (NS_FAILED(rv)) {
+      return rv;
+    }
+
+    if (IsOkToProcessNetworkData()) {
+      nsCOMPtr<nsIParser> kungFuDeathGrip(this);
+      nsCOMPtr<nsIContentSink> sinkDeathGrip(mSink);
+      mProcessingNetworkData = true;
+      if (sinkDeathGrip) {
+        sinkDeathGrip->WillParse();
+      }
+      rv = ResumeParse();
+      mProcessingNetworkData = false;
+    }
+  } else {
+    rv = NS_ERROR_UNEXPECTED;
+  }
+
+  return rv;
+}
+
+/**
+ *  This is called by the networking library once the last block of data
+ *  has been collected from the net.
+ */
+nsresult nsParser::OnStopRequest(nsIRequest* request, nsresult status) {
+  if (mInternalState == NS_ERROR_OUT_OF_MEMORY) {
+    // Checking NS_ERROR_OUT_OF_MEMORY instead of NS_FAILED
+    // to avoid introducing unintentional changes to behavior.
+    return mInternalState;
+  }
+
+  nsresult rv = NS_OK;
+
+  if (mParserContext->mRequest == request) {
+    mParserContext->mStreamListenerState = eOnStop;
+    mParserContext->mScanner.SetIncremental(false);
+  }
+
+  mStreamStatus = status;
+
+  if (IsOkToProcessNetworkData() && NS_SUCCEEDED(rv)) {
+    mProcessingNetworkData = true;
+    if (mSink) {
+      mSink->WillParse();
+    }
+    rv = ResumeParse(true, true);
+    mProcessingNetworkData = false;
+  }
+
+  // If the parser isn't enabled, we don't finish parsing till
+  // it is reenabled.
+
+  return rv;
+}
+
+/**
+ * Get this as nsIStreamListener
+ */
+nsIStreamListener* nsParser::GetStreamListener() { return this; }