widget/nsDeviceContextSpecProxy.cpp
author Jonathan Watt <jwatt@jwatt.org>
Fri, 16 Feb 2018 14:53:26 +0000
changeset 404506 bd244079d11a95e00a0c01de562f7735075e07dc
parent 394941 87f5eb24ef4b510fa73db427e80bc011f6160bde
child 417822 29e58ed3f991b1887d743d49237b65b51db15c5d
permissions -rw-r--r--
Bug 1432409 part 1 - Prevent nsDeviceContextSpecProxy using RemotePrintJobChild if initialization fails. r=dholbert When RemotePrintJobChild::InitializePrint sends a message to the parent process to ask it to initialize printing it spins the event loop and waits for a reply. If the parent fails to initialize printing it will send back an error message followed immediately by a second message telling the child process to delete its RemotePrintJobChild. The error message causes the nested event loop to terminate and blocks RemotePrintJobChild::InitializePrint. We then do various async things to clean up, some of which can try to post messages to the parent process's RemotePrintJobParent. This is a problem since the delete message is pending in the child process's event loop resulting in a race between the code that wants to use the RemotePrintJobChild to send a message to the parent process, and the delete event that will make us crash if anyone tries to use the RemotePrintJobChild. This patch makes sure that if nsDeviceContextSpecProxy's BeginDocument returns failure (remote print job initialization failed) that its EndDocument and AbortDocument methods are then no-ops and will not try to use its RemotePrintJobChild. (BeginPage and EndPage are not changed since they are not called if BeginDocument returns an error result.) MozReview-Commit-ID: 2H6GHjngX7R

/* -*- 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/. */

#include "nsDeviceContextSpecProxy.h"

#include "gfxASurface.h"
#include "gfxPlatform.h"
#include "mozilla/gfx/DrawEventRecorder.h"
#include "mozilla/gfx/PrintTargetThebes.h"
#include "mozilla/layout/RemotePrintJobChild.h"
#include "mozilla/RefPtr.h"
#include "mozilla/Unused.h"
#include "nsComponentManagerUtils.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsDirectoryServiceUtils.h"
#include "nsIPrintSession.h"
#include "nsIPrintSettings.h"
#include "nsIUUIDGenerator.h"
#include "private/pprio.h"

using mozilla::Unused;

using namespace mozilla;
using namespace mozilla::gfx;

NS_IMPL_ISUPPORTS(nsDeviceContextSpecProxy, nsIDeviceContextSpec)

NS_IMETHODIMP
nsDeviceContextSpecProxy::Init(nsIWidget* aWidget,
                               nsIPrintSettings* aPrintSettings,
                               bool aIsPrintPreview)
{
  nsresult rv;
  mRealDeviceContextSpec =
    do_CreateInstance("@mozilla.org/gfx/devicecontextspec;1", &rv);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  mRealDeviceContextSpec->Init(nullptr, aPrintSettings, aIsPrintPreview);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    mRealDeviceContextSpec = nullptr;
    return rv;
  }

  mPrintSettings = aPrintSettings;

  if (aIsPrintPreview) {
    return NS_OK;
  }

  // nsIPrintSettings only has a weak reference to nsIPrintSession, so we hold
  // it to make sure it's available for the lifetime of the print.
  rv = mPrintSettings->GetPrintSession(getter_AddRefs(mPrintSession));
  if (NS_FAILED(rv) || !mPrintSession) {
    NS_WARNING("We can't print via the parent without an nsIPrintSession.");
    return NS_ERROR_FAILURE;
  }

  rv = mPrintSession->GetRemotePrintJob(getter_AddRefs(mRemotePrintJob));
  if (NS_FAILED(rv) || !mRemotePrintJob) {
    NS_WARNING("We can't print via the parent without a RemotePrintJobChild.");
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

already_AddRefed<PrintTarget>
nsDeviceContextSpecProxy::MakePrintTarget()
{
  MOZ_ASSERT(mRealDeviceContextSpec);

  double width, height;
  nsresult rv = mPrintSettings->GetEffectivePageSize(&width, &height);
  if (NS_WARN_IF(NS_FAILED(rv)) || width <= 0 || height <= 0) {
    return nullptr;
  }

  // convert twips to points
  width /= TWIPS_PER_POINT_FLOAT;
  height /= TWIPS_PER_POINT_FLOAT;

  RefPtr<gfxASurface> surface = gfxPlatform::GetPlatform()->
    CreateOffscreenSurface(mozilla::gfx::IntSize::Truncate(width, height),
                           mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32);
  if (!surface) {
    return nullptr;
  }

  // The type of PrintTarget that we return here shouldn't really matter since
  // our implementation of GetDrawEventRecorder returns an object, which means
  // the DrawTarget returned by the PrintTarget will be a DrawTargetWrapAndRecord.
  // The recording will be serialized and sent over to the parent process where
  // PrintTranslator::TranslateRecording will call MakePrintTarget (indirectly
  // via PrintTranslator::CreateDrawTarget) on whatever type of
  // nsIDeviceContextSpecProxy is created for the platform that we are running
  // on.  It is that DrawTarget that the recording will be replayed on to
  // print.
  // XXX(jwatt): The above isn't quite true.  We do want to use a
  // PrintTargetRecording here, but we can't until bug 1280324 is figured out
  // and fixed otherwise we will cause bug 1280181 to happen again.
  RefPtr<PrintTarget> target = PrintTargetThebes::CreateOrNull(surface);

  return target.forget();
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::GetDrawEventRecorder(mozilla::gfx::DrawEventRecorder** aDrawEventRecorder)
{
  MOZ_ASSERT(aDrawEventRecorder);
  RefPtr<mozilla::gfx::DrawEventRecorder> result = mRecorder;
  result.forget(aDrawEventRecorder);
  return NS_OK;
}

float
nsDeviceContextSpecProxy::GetDPI()
{
  MOZ_ASSERT(mRealDeviceContextSpec);

  return mRealDeviceContextSpec->GetDPI();
}

float
nsDeviceContextSpecProxy::GetPrintingScale()
{
  MOZ_ASSERT(mRealDeviceContextSpec);

  return mRealDeviceContextSpec->GetPrintingScale();
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::BeginDocument(const nsAString& aTitle,
                                        const nsAString& aPrintToFileName,
                                        int32_t aStartPage, int32_t aEndPage)
{
  mRecorder = new mozilla::layout::DrawEventRecorderPRFileDesc();
  nsresult rv = mRemotePrintJob->InitializePrint(nsString(aTitle),
                                                 nsString(aPrintToFileName),
                                                 aStartPage, aEndPage);
  if (NS_FAILED(rv)) {
    // The parent process will send a 'delete' message to tell this process to
    // delete our RemotePrintJobChild.  As soon as we return to the event loop
    // and evaluate that message we will crash if we try to access
    // mRemotePrintJob.  We must not try to use it again.
    mRemotePrintJob = nullptr;
  }
  return rv;
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::EndDocument()
{
  if (mRemotePrintJob) {
    Unused << mRemotePrintJob->SendFinalizePrint();
  }
  return NS_OK;
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::AbortDocument()
{
  if (mRemotePrintJob) {
    Unused << mRemotePrintJob->SendAbortPrint(NS_OK);
  }
  return NS_OK;
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::BeginPage()
{
  mRecorder->OpenFD(mRemotePrintJob->GetNextPageFD());

  return NS_OK;
}

NS_IMETHODIMP
nsDeviceContextSpecProxy::EndPage()
{
  // Send the page recording to the parent.
  mRecorder->Close();
  mRemotePrintJob->ProcessPage();

  return NS_OK;
}