gecko-dev/dom/serializers/nsHTMLContentSerializer.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 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/. */

/*
 * nsIContentSerializer implementation that can be used with an
 * nsIDocumentEncoder to convert an HTML (not XHTML!) DOM to an HTML
 * string that could be parsed into more or less the original DOM.
 */

#include "nsHTMLContentSerializer.h"

#include "nsIContent.h"
#include "mozilla/dom/Document.h"
#include "nsElementTable.h"
#include "nsNameSpaceManager.h"
#include "nsString.h"
#include "nsUnicharUtils.h"
#include "nsIDocumentEncoder.h"
#include "nsGkAtoms.h"
#include "nsIURI.h"
#include "nsNetUtil.h"
#include "nsEscape.h"
#include "nsCRT.h"
#include "nsContentUtils.h"
#include "nsIScriptElement.h"
#include "nsAttrName.h"
#include "mozilla/dom/Element.h"
#include "nsParserConstants.h"

using namespace mozilla::dom;

nsresult NS_NewHTMLContentSerializer(nsIContentSerializer** aSerializer) {
  RefPtr<nsHTMLContentSerializer> it = new nsHTMLContentSerializer();
  it.forget(aSerializer);
  return NS_OK;
}

nsHTMLContentSerializer::nsHTMLContentSerializer() { mIsHTMLSerializer = true; }

nsHTMLContentSerializer::~nsHTMLContentSerializer() = default;

NS_IMETHODIMP
nsHTMLContentSerializer::AppendDocumentStart(Document* aDocument) {
  return NS_OK;
}

bool nsHTMLContentSerializer::SerializeHTMLAttributes(
    Element* aElement, Element* aOriginalElement, nsAString& aTagPrefix,
    const nsAString& aTagNamespaceURI, nsAtom* aTagName, int32_t aNamespace,
    nsAString& aStr) {
  MaybeSerializeIsValue(aElement, aStr);

  int32_t count = aElement->GetAttrCount();
  if (!count) return true;

  nsresult rv;
  nsAutoString valueStr;

  for (int32_t index = 0; index < count; index++) {
    const nsAttrName* name = aElement->GetAttrNameAt(index);
    int32_t namespaceID = name->NamespaceID();
    nsAtom* attrName = name->LocalName();

    // Filter out any attribute starting with [-|_]moz
    nsDependentAtomString attrNameStr(attrName);
    if (StringBeginsWith(attrNameStr, u"_moz"_ns) ||
        StringBeginsWith(attrNameStr, u"-moz"_ns)) {
      continue;
    }
    aElement->GetAttr(namespaceID, attrName, valueStr);

    if (mIsCopying && mIsFirstChildOfOL && aTagName == nsGkAtoms::li &&
        aNamespace == kNameSpaceID_XHTML && attrName == nsGkAtoms::value &&
        namespaceID == kNameSpaceID_None) {
      // This is handled separately in SerializeLIValueAttribute()
      continue;
    }
    bool isJS = IsJavaScript(aElement, attrName, namespaceID, valueStr);

    if (((attrName == nsGkAtoms::href && (namespaceID == kNameSpaceID_None ||
                                          namespaceID == kNameSpaceID_XLink)) ||
         (attrName == nsGkAtoms::src && namespaceID == kNameSpaceID_None))) {
      // Make all links absolute when converting only the selection:
      if (mFlags & nsIDocumentEncoder::OutputAbsoluteLinks) {
        // Would be nice to handle OBJECT tags, but that gets more complicated
        // since we have to search the tag list for CODEBASE as well. For now,
        // just leave them relative.
        nsIURI* uri = aElement->GetBaseURI();
        if (uri) {
          nsAutoString absURI;
          rv = NS_MakeAbsoluteURI(absURI, valueStr, uri);
          if (NS_SUCCEEDED(rv)) {
            valueStr = absURI;
          }
        }
      }
    }

    if (mRewriteEncodingDeclaration && aTagName == nsGkAtoms::meta &&
        aNamespace == kNameSpaceID_XHTML && attrName == nsGkAtoms::content &&
        namespaceID == kNameSpaceID_None) {
      // If we're serializing a <meta http-equiv="content-type">,
      // use the proper value, rather than what's in the document.
      nsAutoString header;
      aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::httpEquiv, header);
      if (header.LowerCaseEqualsLiteral("content-type")) {
        valueStr = u"text/html; charset="_ns + NS_ConvertASCIItoUTF16(mCharset);
      }
    }

    nsDependentAtomString nameStr(attrName);
    nsAutoString prefix;
    if (namespaceID == kNameSpaceID_XML) {
      prefix.AssignLiteral(u"xml");
    } else if (namespaceID == kNameSpaceID_XLink) {
      prefix.AssignLiteral(u"xlink");
    }

    // Expand shorthand attribute.
    if (aNamespace == kNameSpaceID_XHTML && namespaceID == kNameSpaceID_None &&
        IsShorthandAttr(attrName, aTagName) && valueStr.IsEmpty()) {
      valueStr = nameStr;
    }
    NS_ENSURE_TRUE(SerializeAttr(prefix, nameStr, valueStr, aStr, !isJS),
                   false);
  }

  return true;
}

NS_IMETHODIMP
nsHTMLContentSerializer::AppendElementStart(Element* aElement,
                                            Element* aOriginalElement) {
  NS_ENSURE_ARG(aElement);
  NS_ENSURE_STATE(mOutput);

  bool forceFormat = false;
  nsresult rv = NS_OK;
  if (!CheckElementStart(aElement, forceFormat, *mOutput, rv)) {
    // When we go to AppendElementEnd for this element, we're going to
    // MaybeLeaveFromPreContent().  So make sure to MaybeEnterInPreContent()
    // now, so our PreLevel() doesn't get confused.
    MaybeEnterInPreContent(aElement);
    return rv;
  }

  NS_ENSURE_SUCCESS(rv, rv);

  nsAtom* name = aElement->NodeInfo()->NameAtom();
  int32_t ns = aElement->GetNameSpaceID();

  bool lineBreakBeforeOpen = LineBreakBeforeOpen(ns, name);

  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel()) {
    if (mColPos && lineBreakBeforeOpen) {
      NS_ENSURE_TRUE(AppendNewLineToString(*mOutput), NS_ERROR_OUT_OF_MEMORY);
    } else {
      NS_ENSURE_TRUE(MaybeAddNewlineForRootNode(*mOutput),
                     NS_ERROR_OUT_OF_MEMORY);
    }
    if (!mColPos) {
      NS_ENSURE_TRUE(AppendIndentation(*mOutput), NS_ERROR_OUT_OF_MEMORY);
    } else if (mAddSpace) {
      bool result = AppendToString(char16_t(' '), *mOutput);
      mAddSpace = false;
      NS_ENSURE_TRUE(result, NS_ERROR_OUT_OF_MEMORY);
    }
  } else if (mAddSpace) {
    bool result = AppendToString(char16_t(' '), *mOutput);
    mAddSpace = false;
    NS_ENSURE_TRUE(result, NS_ERROR_OUT_OF_MEMORY);
  } else {
    NS_ENSURE_TRUE(MaybeAddNewlineForRootNode(*mOutput),
                   NS_ERROR_OUT_OF_MEMORY);
  }
  // Always reset to avoid false newlines in case MaybeAddNewlineForRootNode
  // wasn't called
  mAddNewlineForRootNode = false;

  NS_ENSURE_TRUE(AppendToString(kLessThan, *mOutput), NS_ERROR_OUT_OF_MEMORY);

  NS_ENSURE_TRUE(AppendToString(nsDependentAtomString(name), *mOutput),
                 NS_ERROR_OUT_OF_MEMORY);

  MaybeEnterInPreContent(aElement);

  // for block elements, we increase the indentation
  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel())
    NS_ENSURE_TRUE(IncrIndentation(name), NS_ERROR_OUT_OF_MEMORY);

  // Need to keep track of OL and LI elements in order to get ordinal number
  // for the LI.
  if (mIsCopying && name == nsGkAtoms::ol && ns == kNameSpaceID_XHTML) {
    // We are copying and current node is an OL;
    // Store its start attribute value in olState->startVal.
    nsAutoString start;
    int32_t startAttrVal = 0;

    aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::start, start);
    if (!start.IsEmpty()) {
      nsresult rv = NS_OK;
      startAttrVal = start.ToInteger(&rv);
      // If OL has "start" attribute, first LI element has to start with that
      // value Therefore subtracting 1 as all the LI elements are incrementing
      // it before using it; In failure of ToInteger(), default StartAttrValue
      // to 0.
      if (NS_SUCCEEDED(rv))
        startAttrVal--;
      else
        startAttrVal = 0;
    }
    mOLStateStack.AppendElement(olState(startAttrVal, true));
  }

  if (mIsCopying && name == nsGkAtoms::li && ns == kNameSpaceID_XHTML) {
    mIsFirstChildOfOL = IsFirstChildOfOL(aOriginalElement);
    if (mIsFirstChildOfOL) {
      // If OL is parent of this LI, serialize attributes in different manner.
      NS_ENSURE_TRUE(SerializeLIValueAttribute(aElement, *mOutput),
                     NS_ERROR_OUT_OF_MEMORY);
    }
  }

  // Even LI passed above have to go through this
  // for serializing attributes other than "value".
  nsAutoString dummyPrefix;
  NS_ENSURE_TRUE(
      SerializeHTMLAttributes(aElement, aOriginalElement, dummyPrefix, u""_ns,
                              name, ns, *mOutput),
      NS_ERROR_OUT_OF_MEMORY);

  NS_ENSURE_TRUE(AppendToString(kGreaterThan, *mOutput),
                 NS_ERROR_OUT_OF_MEMORY);

  if (ns == kNameSpaceID_XHTML &&
      (name == nsGkAtoms::script || name == nsGkAtoms::style ||
       (name == nsGkAtoms::noscript &&
        aElement->OwnerDoc()->IsScriptEnabled()) ||
       name == nsGkAtoms::noframes)) {
    ++mDisableEntityEncoding;
  }

  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel() &&
      LineBreakAfterOpen(ns, name)) {
    NS_ENSURE_TRUE(AppendNewLineToString(*mOutput), NS_ERROR_OUT_OF_MEMORY);
  }

  NS_ENSURE_TRUE(AfterElementStart(aElement, aOriginalElement, *mOutput),
                 NS_ERROR_OUT_OF_MEMORY);

  return NS_OK;
}

NS_IMETHODIMP
nsHTMLContentSerializer::AppendElementEnd(Element* aElement,
                                          Element* aOriginalElement) {
  NS_ENSURE_ARG(aElement);
  NS_ENSURE_STATE(mOutput);

  nsAtom* name = aElement->NodeInfo()->NameAtom();
  int32_t ns = aElement->GetNameSpaceID();

  if (ns == kNameSpaceID_XHTML &&
      (name == nsGkAtoms::script || name == nsGkAtoms::style ||
       (name == nsGkAtoms::noscript &&
        aElement->OwnerDoc()->IsScriptEnabled()) ||
       name == nsGkAtoms::noframes)) {
    --mDisableEntityEncoding;
  }

  bool forceFormat = !(mFlags & nsIDocumentEncoder::OutputIgnoreMozDirty) &&
                     aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::mozdirty);

  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel()) {
    DecrIndentation(name);
  }

  if (name == nsGkAtoms::script) {
    nsCOMPtr<nsIScriptElement> script = do_QueryInterface(aElement);

    if (ShouldMaintainPreLevel() && script && script->IsMalformed()) {
      // We're looking at a malformed script tag. This means that the end tag
      // was missing in the source. Imitate that here by not serializing the end
      // tag.
      --PreLevel();
      return NS_OK;
    }
  } else if (mIsCopying && name == nsGkAtoms::ol && ns == kNameSpaceID_XHTML) {
    NS_ASSERTION((!mOLStateStack.IsEmpty()), "Cannot have an empty OL Stack");
    /* Though at this point we must always have an state to be deleted as all
    the OL opening tags are supposed to push an olState object to the stack*/
    if (!mOLStateStack.IsEmpty()) {
      mOLStateStack.RemoveLastElement();
    }
  }

  if (ns == kNameSpaceID_XHTML) {
    bool isContainer =
        nsHTMLElement::IsContainer(nsHTMLTags::CaseSensitiveAtomTagToId(name));
    if (!isContainer) {
      // Keep this in sync with the cleanup at the end of this method.
      MOZ_ASSERT(name != nsGkAtoms::body);
      MaybeLeaveFromPreContent(aElement);
      return NS_OK;
    }
  }

  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel()) {
    bool lineBreakBeforeClose = LineBreakBeforeClose(ns, name);

    if (mColPos && lineBreakBeforeClose) {
      NS_ENSURE_TRUE(AppendNewLineToString(*mOutput), NS_ERROR_OUT_OF_MEMORY);
    }
    if (!mColPos) {
      NS_ENSURE_TRUE(AppendIndentation(*mOutput), NS_ERROR_OUT_OF_MEMORY);
    } else if (mAddSpace) {
      bool result = AppendToString(char16_t(' '), *mOutput);
      mAddSpace = false;
      NS_ENSURE_TRUE(result, NS_ERROR_OUT_OF_MEMORY);
    }
  } else if (mAddSpace) {
    bool result = AppendToString(char16_t(' '), *mOutput);
    mAddSpace = false;
    NS_ENSURE_TRUE(result, NS_ERROR_OUT_OF_MEMORY);
  }

  NS_ENSURE_TRUE(AppendToString(kEndTag, *mOutput), NS_ERROR_OUT_OF_MEMORY);
  NS_ENSURE_TRUE(AppendToString(nsDependentAtomString(name), *mOutput),
                 NS_ERROR_OUT_OF_MEMORY);
  NS_ENSURE_TRUE(AppendToString(kGreaterThan, *mOutput),
                 NS_ERROR_OUT_OF_MEMORY);

  // Keep this cleanup in sync with the IsContainer() early return above.
  MaybeLeaveFromPreContent(aElement);

  if ((mDoFormat || forceFormat) && !mDoRaw && !PreLevel() &&
      LineBreakAfterClose(ns, name)) {
    NS_ENSURE_TRUE(AppendNewLineToString(*mOutput), NS_ERROR_OUT_OF_MEMORY);
  } else {
    MaybeFlagNewlineForRootNode(aElement);
  }

  if (name == nsGkAtoms::body && ns == kNameSpaceID_XHTML) {
    --mInBody;
  }

  return NS_OK;
}

static const uint16_t kValNBSP = 160;

#define _ 0

// This table indexes into kEntityStrings[].
const uint8_t nsHTMLContentSerializer::kEntities[] = {
    // clang-format off
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, 2, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  3, _, 4, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  5
    // clang-format on
};

// This table indexes into kEntityStrings[].
const uint8_t nsHTMLContentSerializer::kAttrEntities[] = {
    // clang-format off
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, 1, _, _, _, 2, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  3, _, 4, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  _, _, _, _, _, _, _, _, _, _,
  5
    // clang-format on
};

#undef _

const char* const nsHTMLContentSerializer::kEntityStrings[] = {
    /* 0 */ nullptr,
    /* 1 */ "&quot;",
    /* 2 */ "&amp;",
    /* 3 */ "&lt;",
    /* 4 */ "&gt;",
    /* 5 */ "&nbsp;"};

bool nsHTMLContentSerializer::AppendAndTranslateEntities(
    const nsAString& aStr, nsAString& aOutputStr) {
  if (mBodyOnly && !mInBody) {
    return true;
  }

  if (mDisableEntityEncoding) {
    return aOutputStr.Append(aStr, mozilla::fallible);
  }

  if (mFlags & (nsIDocumentEncoder::OutputEncodeBasicEntities)) {
    // Per the API documentation, encode &nbsp;, &amp;, &lt;, &gt;, and &quot;
    if (mInAttribute) {
      return nsXMLContentSerializer::AppendAndTranslateEntities<kValNBSP>(
          aStr, aOutputStr, kAttrEntities, kEntityStrings);
    }

    return nsXMLContentSerializer::AppendAndTranslateEntities<kValNBSP>(
        aStr, aOutputStr, kEntities, kEntityStrings);
  }

  // We don't want to call into our superclass 2-arg version of
  // AppendAndTranslateEntities, because it wants to encode more characters
  // than we do.  Use our tables, but avoid encoding &nbsp; by passing in a
  // smaller max index.  This will only encode &amp;, &lt;, &gt;, and &quot;.
  if (mInAttribute) {
    return nsXMLContentSerializer::AppendAndTranslateEntities<kGTVal>(
        aStr, aOutputStr, kAttrEntities, kEntityStrings);
  }

  return nsXMLContentSerializer::AppendAndTranslateEntities<kGTVal>(
      aStr, aOutputStr, kEntities, kEntityStrings);
}