netwerk/base/nsIncrementalDownload.cpp
author Andrew Osmond <aosmond@mozilla.com>
Fri, 17 Nov 2017 06:45:28 -0500
changeset 392351 b9a29d94ccac646c9336fa75e084bbc8581501ad
parent 386356 fa53cb4191939e1d66446f5e45175e0079197082
child 400585 e875f3702a5fad7f7af630088d97424656b79702
permissions -rw-r--r--
Bug 1368776 - Part 15. Cache flags passed to ImageResource::GetImageContainerImpl for consistency. r=tnikkel When FLAG_HIGH_QUALITY_SCALING is used, we need to make sure we continue using that flag when we update the container. We should also use it for comparing whether or not an existing image container is equivalent.

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "mozilla/Attributes.h"
#include "mozilla/UniquePtrExtensions.h"
#include "mozilla/UniquePtr.h"

#include "nsIIncrementalDownload.h"
#include "nsIRequestObserver.h"
#include "nsIProgressEventSink.h"
#include "nsIChannelEventSink.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIInterfaceRequestor.h"
#include "nsIObserverService.h"
#include "nsIObserver.h"
#include "nsIStreamListener.h"
#include "nsIFile.h"
#include "nsITimer.h"
#include "nsIURI.h"
#include "nsIInputStream.h"
#include "nsNetUtil.h"
#include "nsWeakReference.h"
#include "prio.h"
#include "prprf.h"
#include <algorithm>
#include "nsIContentPolicy.h"
#include "nsContentUtils.h"
#include "mozilla/UniquePtr.h"

// Default values used to initialize a nsIncrementalDownload object.
#define DEFAULT_CHUNK_SIZE (4096 * 16)  // bytes
#define DEFAULT_INTERVAL    60          // seconds

#define UPDATE_PROGRESS_INTERVAL PRTime(500 * PR_USEC_PER_MSEC) // 500ms

// Number of times to retry a failed byte-range request.
#define MAX_RETRY_COUNT 20

using namespace mozilla;

//-----------------------------------------------------------------------------

static nsresult
WriteToFile(nsIFile *lf, const char *data, uint32_t len, int32_t flags)
{
  PRFileDesc *fd;
  int32_t mode = 0600;
  nsresult rv;
  rv = lf->OpenNSPRFileDesc(flags, mode, &fd);
  if (NS_FAILED(rv))
    return rv;

  if (len)
    rv = PR_Write(fd, data, len) == int32_t(len) ? NS_OK : NS_ERROR_FAILURE;

  PR_Close(fd);
  return rv;
}

static nsresult
AppendToFile(nsIFile *lf, const char *data, uint32_t len)
{
  int32_t flags = PR_WRONLY | PR_CREATE_FILE | PR_APPEND;
  return WriteToFile(lf, data, len, flags);
}

// maxSize may be -1 if unknown
static void
MakeRangeSpec(const int64_t &size, const int64_t &maxSize, int32_t chunkSize,
              bool fetchRemaining, nsCString &rangeSpec)
{
  rangeSpec.AssignLiteral("bytes=");
  rangeSpec.AppendInt(int64_t(size));
  rangeSpec.Append('-');

  if (fetchRemaining)
    return;

  int64_t end = size + int64_t(chunkSize);
  if (maxSize != int64_t(-1) && end > maxSize)
    end = maxSize;
  end -= 1;

  rangeSpec.AppendInt(int64_t(end));
}

//-----------------------------------------------------------------------------

class nsIncrementalDownload final
  : public nsIIncrementalDownload
  , public nsIStreamListener
  , public nsIObserver
  , public nsIInterfaceRequestor
  , public nsIChannelEventSink
  , public nsSupportsWeakReference
  , public nsIAsyncVerifyRedirectCallback
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIREQUEST
  NS_DECL_NSIINCREMENTALDOWNLOAD
  NS_DECL_NSIREQUESTOBSERVER
  NS_DECL_NSISTREAMLISTENER
  NS_DECL_NSIOBSERVER
  NS_DECL_NSIINTERFACEREQUESTOR
  NS_DECL_NSICHANNELEVENTSINK
  NS_DECL_NSIASYNCVERIFYREDIRECTCALLBACK

  nsIncrementalDownload();

private:
  ~nsIncrementalDownload() {}
  nsresult FlushChunk();
  void     UpdateProgress();
  nsresult CallOnStartRequest();
  void     CallOnStopRequest();
  nsresult StartTimer(int32_t interval);
  nsresult ProcessTimeout();
  nsresult ReadCurrentSize();
  nsresult ClearRequestHeader(nsIHttpChannel *channel);

  nsCOMPtr<nsIRequestObserver>             mObserver;
  nsCOMPtr<nsISupports>                    mObserverContext;
  nsCOMPtr<nsIProgressEventSink>           mProgressSink;
  nsCOMPtr<nsIURI>                         mURI;
  nsCOMPtr<nsIURI>                         mFinalURI;
  nsCOMPtr<nsIFile>                        mDest;
  nsCOMPtr<nsIChannel>                     mChannel;
  nsCOMPtr<nsITimer>                       mTimer;
  mozilla::UniquePtr<char[]>               mChunk;
  int32_t                                  mChunkLen;
  int32_t                                  mChunkSize;
  int32_t                                  mInterval;
  int64_t                                  mTotalSize;
  int64_t                                  mCurrentSize;
  uint32_t                                 mLoadFlags;
  int32_t                                  mNonPartialCount;
  nsresult                                 mStatus;
  bool                                     mIsPending;
  bool                                     mDidOnStartRequest;
  PRTime                                   mLastProgressUpdate;
  nsCOMPtr<nsIAsyncVerifyRedirectCallback> mRedirectCallback;
  nsCOMPtr<nsIChannel>                     mNewRedirectChannel;
  nsCString                                mPartialValidator;
  bool                                     mCacheBust;
};

nsIncrementalDownload::nsIncrementalDownload()
  : mChunkLen(0)
  , mChunkSize(DEFAULT_CHUNK_SIZE)
  , mInterval(DEFAULT_INTERVAL)
  , mTotalSize(-1)
  , mCurrentSize(-1)
  , mLoadFlags(LOAD_NORMAL)
  , mNonPartialCount(0)
  , mStatus(NS_OK)
  , mIsPending(false)
  , mDidOnStartRequest(false)
  , mLastProgressUpdate(0)
  , mRedirectCallback(nullptr)
  , mNewRedirectChannel(nullptr)
  , mCacheBust(false)
{
}

nsresult
nsIncrementalDownload::FlushChunk()
{
  NS_ASSERTION(mTotalSize != int64_t(-1), "total size should be known");

  if (mChunkLen == 0)
    return NS_OK;

  nsresult rv = AppendToFile(mDest, mChunk.get(), mChunkLen);
  if (NS_FAILED(rv))
    return rv;

  mCurrentSize += int64_t(mChunkLen);
  mChunkLen = 0;

  return NS_OK;
}

void
nsIncrementalDownload::UpdateProgress()
{
  mLastProgressUpdate = PR_Now();

  if (mProgressSink)
    mProgressSink->OnProgress(this, mObserverContext,
                              mCurrentSize + mChunkLen,
                              mTotalSize);
}

nsresult
nsIncrementalDownload::CallOnStartRequest()
{
  if (!mObserver || mDidOnStartRequest)
    return NS_OK;

  mDidOnStartRequest = true;
  return mObserver->OnStartRequest(this, mObserverContext);
}

void
nsIncrementalDownload::CallOnStopRequest()
{
  if (!mObserver)
    return;

  // Ensure that OnStartRequest is always called once before OnStopRequest.
  nsresult rv = CallOnStartRequest();
  if (NS_SUCCEEDED(mStatus))
    mStatus = rv;

  mIsPending = false;

  mObserver->OnStopRequest(this, mObserverContext, mStatus);
  mObserver = nullptr;
  mObserverContext = nullptr;
}

nsresult
nsIncrementalDownload::StartTimer(int32_t interval)
{
  return NS_NewTimerWithObserver(getter_AddRefs(mTimer),
                                 this, interval * 1000,
                                 nsITimer::TYPE_ONE_SHOT);
}

nsresult
nsIncrementalDownload::ProcessTimeout()
{
  NS_ASSERTION(!mChannel, "how can we have a channel?");

  // Handle existing error conditions
  if (NS_FAILED(mStatus)) {
    CallOnStopRequest();
    return NS_OK;
  }

  // Fetch next chunk

  nsCOMPtr<nsIChannel> channel;
  nsresult rv = NS_NewChannel(getter_AddRefs(channel),
                              mFinalURI,
                              nsContentUtils::GetSystemPrincipal(),
                              nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL,
                              nsIContentPolicy::TYPE_OTHER,
                              nullptr,   // loadGroup
                              this,      // aCallbacks
                              mLoadFlags);

  if (NS_FAILED(rv))
    return rv;

  nsCOMPtr<nsIHttpChannel> http = do_QueryInterface(channel, &rv);
  if (NS_FAILED(rv))
    return rv;

  NS_ASSERTION(mCurrentSize != int64_t(-1),
      "we should know the current file size by now");

  rv = ClearRequestHeader(http);
  if (NS_FAILED(rv))
    return rv;

  // Don't bother making a range request if we are just going to fetch the
  // entire document.
  if (mInterval || mCurrentSize != int64_t(0)) {
    nsAutoCString range;
    MakeRangeSpec(mCurrentSize, mTotalSize, mChunkSize, mInterval == 0, range);

    rv = http->SetRequestHeader(NS_LITERAL_CSTRING("Range"), range, false);
    if (NS_FAILED(rv))
      return rv;

    if (!mPartialValidator.IsEmpty()) {
      rv = http->SetRequestHeader(NS_LITERAL_CSTRING("If-Range"),
                                  mPartialValidator, false);
      if (NS_FAILED(rv)) {
        LOG(("nsIncrementalDownload::ProcessTimeout\n"
             "    failed to set request header: If-Range\n"));
      }
    }

    if (mCacheBust) {
      rv = http->SetRequestHeader(NS_LITERAL_CSTRING("Cache-Control"),
                                  NS_LITERAL_CSTRING("no-cache"), false);
      if (NS_FAILED(rv)) {
        LOG(("nsIncrementalDownload::ProcessTimeout\n"
             "    failed to set request header: If-Range\n"));
      }
      rv = http->SetRequestHeader(NS_LITERAL_CSTRING("Pragma"),
                                  NS_LITERAL_CSTRING("no-cache"), false);
      if (NS_FAILED(rv)) {
        LOG(("nsIncrementalDownload::ProcessTimeout\n"
             "    failed to set request header: If-Range\n"));
      }
    }
  }

  rv = channel->AsyncOpen2(this);
  if (NS_FAILED(rv))
    return rv;

  // Wait to assign mChannel when we know we are going to succeed.  This is
  // important because we don't want to introduce a reference cycle between
  // mChannel and this until we know for a fact that AsyncOpen has succeeded,
  // thus ensuring that our stream listener methods will be invoked.
  mChannel = channel;
  return NS_OK;
}

// Reads the current file size and validates it.
nsresult
nsIncrementalDownload::ReadCurrentSize()
{
  int64_t size;
  nsresult rv = mDest->GetFileSize((int64_t *) &size);
  if (rv == NS_ERROR_FILE_NOT_FOUND ||
      rv == NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) {
    mCurrentSize = 0;
    return NS_OK;
  }
  if (NS_FAILED(rv))
    return rv;

  mCurrentSize = size;
  return NS_OK;
}

// nsISupports

NS_IMPL_ISUPPORTS(nsIncrementalDownload,
                  nsIIncrementalDownload,
                  nsIRequest,
                  nsIStreamListener,
                  nsIRequestObserver,
                  nsIObserver,
                  nsIInterfaceRequestor,
                  nsIChannelEventSink,
                  nsISupportsWeakReference,
                  nsIAsyncVerifyRedirectCallback)

// nsIRequest

NS_IMETHODIMP
nsIncrementalDownload::GetName(nsACString &name)
{
  NS_ENSURE_TRUE(mURI, NS_ERROR_NOT_INITIALIZED);

  return mURI->GetSpec(name);
}

NS_IMETHODIMP
nsIncrementalDownload::IsPending(bool *isPending)
{
  *isPending = mIsPending;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetStatus(nsresult *status)
{
  *status = mStatus;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::Cancel(nsresult status)
{
  NS_ENSURE_ARG(NS_FAILED(status));

  // Ignore this cancelation if we're already canceled.
  if (NS_FAILED(mStatus))
    return NS_OK;

  mStatus = status;

  // Nothing more to do if callbacks aren't pending.
  if (!mIsPending)
    return NS_OK;

  if (mChannel) {
    mChannel->Cancel(mStatus);
    NS_ASSERTION(!mTimer, "what is this timer object doing here?");
  }
  else {
    // dispatch a timer callback event to drive invoking our listener's
    // OnStopRequest.
    if (mTimer)
      mTimer->Cancel();
    StartTimer(0);
  }

  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::Suspend()
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsIncrementalDownload::Resume()
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsIncrementalDownload::GetLoadFlags(nsLoadFlags *loadFlags)
{
  *loadFlags = mLoadFlags;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::SetLoadFlags(nsLoadFlags loadFlags)
{
  mLoadFlags = loadFlags;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetLoadGroup(nsILoadGroup **loadGroup)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsIncrementalDownload::SetLoadGroup(nsILoadGroup *loadGroup)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

// nsIIncrementalDownload

NS_IMETHODIMP
nsIncrementalDownload::Init(nsIURI *uri, nsIFile *dest,
                            int32_t chunkSize, int32_t interval)
{
  // Keep it simple: only allow initialization once
  NS_ENSURE_FALSE(mURI, NS_ERROR_ALREADY_INITIALIZED);

  mDest = do_QueryInterface(dest);
  NS_ENSURE_ARG(mDest);

  mURI = uri;
  mFinalURI = uri;

  if (chunkSize > 0)
    mChunkSize = chunkSize;
  if (interval >= 0)
    mInterval = interval;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetURI(nsIURI **result)
{
  NS_IF_ADDREF(*result = mURI);
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetFinalURI(nsIURI **result)
{
  NS_IF_ADDREF(*result = mFinalURI);
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetDestination(nsIFile **result)
{
  if (!mDest) {
    *result = nullptr;
    return NS_OK;
  }
  // Return a clone of mDest so that callers may modify the resulting nsIFile
  // without corrupting our internal object.  This also works around the fact
  // that some nsIFile impls may cache the result of stat'ing the filesystem.
  return mDest->Clone(result);
}

NS_IMETHODIMP
nsIncrementalDownload::GetTotalSize(int64_t *result)
{
  *result = mTotalSize;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::GetCurrentSize(int64_t *result)
{
  *result = mCurrentSize;
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::Start(nsIRequestObserver *observer,
                             nsISupports *context)
{
  NS_ENSURE_ARG(observer);
  NS_ENSURE_FALSE(mIsPending, NS_ERROR_IN_PROGRESS);

  // Observe system shutdown so we can be sure to release any reference held
  // between ourselves and the timer.  We have the observer service hold a weak
  // reference to us, so that we don't have to worry about calling
  // RemoveObserver.  XXX(darin): The timer code should do this for us.
  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
  if (obs)
    obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, true);

  nsresult rv = ReadCurrentSize();
  if (NS_FAILED(rv))
    return rv;

  rv = StartTimer(0);
  if (NS_FAILED(rv))
    return rv;

  mObserver = observer;
  mObserverContext = context;
  mProgressSink = do_QueryInterface(observer);  // ok if null

  mIsPending = true;
  return NS_OK;
}

// nsIRequestObserver

NS_IMETHODIMP
nsIncrementalDownload::OnStartRequest(nsIRequest *request,
                                      nsISupports *context)
{
  nsresult rv;

  nsCOMPtr<nsIHttpChannel> http = do_QueryInterface(request, &rv);
  if (NS_FAILED(rv))
    return rv;

  // Ensure that we are receiving a 206 response.
  uint32_t code;
  rv = http->GetResponseStatus(&code);
  if (NS_FAILED(rv))
    return rv;
  if (code != 206) {
    // We may already have the entire file downloaded, in which case
    // our request for a range beyond the end of the file would have
    // been met with an error response code.
    if (code == 416 && mTotalSize == int64_t(-1)) {
      mTotalSize = mCurrentSize;
      // Return an error code here to suppress OnDataAvailable.
      return NS_ERROR_DOWNLOAD_COMPLETE;
    }
    // The server may have decided to give us all of the data in one chunk.  If
    // we requested a partial range, then we don't want to download all of the
    // data at once.  So, we'll just try again, but if this keeps happening then
    // we'll eventually give up.
    if (code == 200) {
      if (mInterval) {
        mChannel = nullptr;
        if (++mNonPartialCount > MAX_RETRY_COUNT) {
          NS_WARNING("unable to fetch a byte range; giving up");
          return NS_ERROR_FAILURE;
        }
        // Increase delay with each failure.
        StartTimer(mInterval * mNonPartialCount);
        return NS_ERROR_DOWNLOAD_NOT_PARTIAL;
      }
      // Since we have been asked to download the rest of the file, we can deal
      // with a 200 response.  This may result in downloading the beginning of
      // the file again, but that can't really be helped.
    } else {
      NS_WARNING("server response was unexpected");
      return NS_ERROR_UNEXPECTED;
    }
  } else {
    // We got a partial response, so clear this counter in case the next chunk
    // results in a 200 response.
    mNonPartialCount = 0;

    // confirm that the content-range response header is consistent with
    // expectations on each 206. If it is not then drop this response and
    // retry with no-cache set.
    if (!mCacheBust) {
      nsAutoCString buf;
      int64_t startByte = 0;
      bool confirmedOK = false;

      rv = http->GetResponseHeader(NS_LITERAL_CSTRING("Content-Range"), buf);
      if (NS_FAILED(rv))
        return rv; // it isn't a useful 206 without a CONTENT-RANGE of some sort

      // Content-Range: bytes 0-299999/25604694
      int32_t p = buf.Find("bytes ");

      // first look for the starting point of the content-range
      // to make sure it is what we expect
      if (p != -1) {
        char *endptr = nullptr;
        const char *s = buf.get() + p + 6;
        while (*s && *s == ' ')
          s++;
        startByte = strtol(s, &endptr, 10);

        if (*s && endptr && (endptr != s) &&
            (mCurrentSize == startByte)) {

          // ok the starting point is confirmed. We still need to check the
          // total size of the range for consistency if this isn't
          // the first chunk
          if (mTotalSize == int64_t(-1)) {
            // first chunk
            confirmedOK = true;
          } else {
            int32_t slash = buf.FindChar('/');
            int64_t rangeSize = 0;
            if (slash != kNotFound &&
                (PR_sscanf(buf.get() + slash + 1, "%lld", (int64_t *) &rangeSize) == 1) &&
                rangeSize == mTotalSize) {
              confirmedOK = true;
            }
          }
        }
      }

      if (!confirmedOK) {
        NS_WARNING("unexpected content-range");
        mCacheBust = true;
        mChannel = nullptr;
        if (++mNonPartialCount > MAX_RETRY_COUNT) {
          NS_WARNING("unable to fetch a byte range; giving up");
          return NS_ERROR_FAILURE;
        }
        // Increase delay with each failure.
        StartTimer(mInterval * mNonPartialCount);
        return NS_ERROR_DOWNLOAD_NOT_PARTIAL;
      }
    }
  }

  // Do special processing after the first response.
  if (mTotalSize == int64_t(-1)) {
    // Update knowledge of mFinalURI
    rv = http->GetURI(getter_AddRefs(mFinalURI));
    if (NS_FAILED(rv))
      return rv;
    Unused << http->GetResponseHeader(NS_LITERAL_CSTRING("Etag"), mPartialValidator);
    if (StringBeginsWith(mPartialValidator, NS_LITERAL_CSTRING("W/")))
      mPartialValidator.Truncate(); // don't use weak validators
    if (mPartialValidator.IsEmpty()) {
      rv = http->GetResponseHeader(NS_LITERAL_CSTRING("Last-Modified"), mPartialValidator);
      if (NS_FAILED(rv)) {
        LOG(("nsIncrementalDownload::OnStartRequest\n"
             "    empty validator\n"));
      }
    }

    if (code == 206) {
      // OK, read the Content-Range header to determine the total size of this
      // download file.
      nsAutoCString buf;
      rv = http->GetResponseHeader(NS_LITERAL_CSTRING("Content-Range"), buf);
      if (NS_FAILED(rv))
        return rv;
      int32_t slash = buf.FindChar('/');
      if (slash == kNotFound) {
        NS_WARNING("server returned invalid Content-Range header!");
        return NS_ERROR_UNEXPECTED;
      }
      if (PR_sscanf(buf.get() + slash + 1, "%lld", (int64_t *) &mTotalSize) != 1)
        return NS_ERROR_UNEXPECTED;
    } else {
      rv = http->GetContentLength(&mTotalSize);
      if (NS_FAILED(rv))
        return rv;
      // We need to know the total size of the thing we're trying to download.
      if (mTotalSize == int64_t(-1)) {
        NS_WARNING("server returned no content-length header!");
        return NS_ERROR_UNEXPECTED;
      }
      // Need to truncate (or create, if it doesn't exist) the file since we
      // are downloading the whole thing.
      WriteToFile(mDest, nullptr, 0, PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE);
      mCurrentSize = 0;
    }

    // Notify observer that we are starting...
    rv = CallOnStartRequest();
    if (NS_FAILED(rv))
      return rv;
  }

  // Adjust mChunkSize accordingly if mCurrentSize is close to mTotalSize.
  int64_t diff = mTotalSize - mCurrentSize;
  if (diff <= int64_t(0)) {
    NS_WARNING("about to set a bogus chunk size; giving up");
    return NS_ERROR_UNEXPECTED;
  }

  if (diff < int64_t(mChunkSize))
    mChunkSize = uint32_t(diff);

  mChunk = mozilla::MakeUniqueFallible<char[]>(mChunkSize);
  if (!mChunk)
    rv = NS_ERROR_OUT_OF_MEMORY;

  return rv;
}

NS_IMETHODIMP
nsIncrementalDownload::OnStopRequest(nsIRequest *request,
                                     nsISupports *context,
                                     nsresult status)
{
  // Not a real error; just a trick to kill off the channel without our
  // listener having to care.
  if (status == NS_ERROR_DOWNLOAD_NOT_PARTIAL)
    return NS_OK;

  // Not a real error; just a trick used to suppress OnDataAvailable calls.
  if (status == NS_ERROR_DOWNLOAD_COMPLETE)
    status = NS_OK;

  if (NS_SUCCEEDED(mStatus))
    mStatus = status;

  if (mChunk) {
    if (NS_SUCCEEDED(mStatus))
      mStatus = FlushChunk();

    mChunk = nullptr;  // deletes memory
    mChunkLen = 0;
    UpdateProgress();
  }

  mChannel = nullptr;

  // Notify listener if we hit an error or finished
  if (NS_FAILED(mStatus) || mCurrentSize == mTotalSize) {
    CallOnStopRequest();
    return NS_OK;
  }

  return StartTimer(mInterval);  // Do next chunk
}

// nsIStreamListener

NS_IMETHODIMP
nsIncrementalDownload::OnDataAvailable(nsIRequest *request,
                                       nsISupports *context,
                                       nsIInputStream *input,
                                       uint64_t offset,
                                       uint32_t count)
{
  while (count) {
    uint32_t space = mChunkSize - mChunkLen;
    uint32_t n, len = std::min(space, count);

    nsresult rv = input->Read(&mChunk[mChunkLen], len, &n);
    if (NS_FAILED(rv))
      return rv;
    if (n != len)
      return NS_ERROR_UNEXPECTED;

    count -= n;
    mChunkLen += n;

    if (mChunkLen == mChunkSize) {
      rv = FlushChunk();
      if (NS_FAILED(rv))
        return rv;
    }
  }

  if (PR_Now() > mLastProgressUpdate + UPDATE_PROGRESS_INTERVAL)
    UpdateProgress();

  return NS_OK;
}

// nsIObserver

NS_IMETHODIMP
nsIncrementalDownload::Observe(nsISupports *subject, const char *topic,
                               const char16_t *data)
{
  if (strcmp(topic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
    Cancel(NS_ERROR_ABORT);

    // Since the app is shutting down, we need to go ahead and notify our
    // observer here.  Otherwise, we would notify them after XPCOM has been
    // shutdown or not at all.
    CallOnStopRequest();
  }
  else if (strcmp(topic, NS_TIMER_CALLBACK_TOPIC) == 0) {
    mTimer = nullptr;
    nsresult rv = ProcessTimeout();
    if (NS_FAILED(rv))
      Cancel(rv);
  }
  return NS_OK;
}

// nsIInterfaceRequestor

NS_IMETHODIMP
nsIncrementalDownload::GetInterface(const nsIID &iid, void **result)
{
  if (iid.Equals(NS_GET_IID(nsIChannelEventSink))) {
    NS_ADDREF_THIS();
    *result = static_cast<nsIChannelEventSink *>(this);
    return NS_OK;
  }

  nsCOMPtr<nsIInterfaceRequestor> ir = do_QueryInterface(mObserver);
  if (ir)
    return ir->GetInterface(iid, result);

  return NS_ERROR_NO_INTERFACE;
}

nsresult
nsIncrementalDownload::ClearRequestHeader(nsIHttpChannel *channel)
{
  NS_ENSURE_ARG(channel);

  // We don't support encodings -- they make the Content-Length not equal
  // to the actual size of the data.
  return channel->SetRequestHeader(NS_LITERAL_CSTRING("Accept-Encoding"),
                                   NS_LITERAL_CSTRING(""), false);
}

// nsIChannelEventSink

NS_IMETHODIMP
nsIncrementalDownload::AsyncOnChannelRedirect(nsIChannel *oldChannel,
                                              nsIChannel *newChannel,
                                              uint32_t flags,
                                              nsIAsyncVerifyRedirectCallback *cb)
{
  // In response to a redirect, we need to propagate the Range header.  See bug
  // 311595.  Any failure code returned from this function aborts the redirect.

  nsCOMPtr<nsIHttpChannel> http = do_QueryInterface(oldChannel);
  NS_ENSURE_STATE(http);

  nsCOMPtr<nsIHttpChannel> newHttpChannel = do_QueryInterface(newChannel);
  NS_ENSURE_STATE(newHttpChannel);

  NS_NAMED_LITERAL_CSTRING(rangeHdr, "Range");

  nsresult rv = ClearRequestHeader(newHttpChannel);
  if (NS_FAILED(rv))
    return rv;

  // If we didn't have a Range header, then we must be doing a full download.
  nsAutoCString rangeVal;
  Unused << http->GetRequestHeader(rangeHdr, rangeVal);
  if (!rangeVal.IsEmpty()) {
    rv = newHttpChannel->SetRequestHeader(rangeHdr, rangeVal, false);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // A redirection changes the validator
  mPartialValidator.Truncate();

  if (mCacheBust) {
    rv = newHttpChannel->SetRequestHeader(NS_LITERAL_CSTRING("Cache-Control"),
                                          NS_LITERAL_CSTRING("no-cache"), false);
    if (NS_FAILED(rv)) {
      LOG(("nsIncrementalDownload::AsyncOnChannelRedirect\n"
           "    failed to set request header: Cache-Control\n"));
    }
    rv = newHttpChannel->SetRequestHeader(NS_LITERAL_CSTRING("Pragma"),
                                          NS_LITERAL_CSTRING("no-cache"), false);
    if (NS_FAILED(rv)) {
      LOG(("nsIncrementalDownload::AsyncOnChannelRedirect\n"
           "    failed to set request header: Pragma\n"));
    }
  }

  // Prepare to receive callback
  mRedirectCallback = cb;
  mNewRedirectChannel = newChannel;

  // Give the observer a chance to see this redirect notification.
  nsCOMPtr<nsIChannelEventSink> sink = do_GetInterface(mObserver);
  if (sink) {
    rv = sink->AsyncOnChannelRedirect(oldChannel, newChannel, flags, this);
    if (NS_FAILED(rv)) {
        mRedirectCallback = nullptr;
        mNewRedirectChannel = nullptr;
    }
    return rv;
  }
  (void) OnRedirectVerifyCallback(NS_OK);
  return NS_OK;
}

NS_IMETHODIMP
nsIncrementalDownload::OnRedirectVerifyCallback(nsresult result)
{
  NS_ASSERTION(mRedirectCallback, "mRedirectCallback not set in callback");
  NS_ASSERTION(mNewRedirectChannel, "mNewRedirectChannel not set in callback");

  // Update mChannel, so we can Cancel the new channel.
  if (NS_SUCCEEDED(result))
    mChannel = mNewRedirectChannel;

  mRedirectCallback->OnRedirectVerifyCallback(result);
  mRedirectCallback = nullptr;
  mNewRedirectChannel = nullptr;
  return NS_OK;
}

extern nsresult
net_NewIncrementalDownload(nsISupports *outer, const nsIID &iid, void **result)
{
  if (outer)
    return NS_ERROR_NO_AGGREGATION;

  nsIncrementalDownload *d = new nsIncrementalDownload();
  if (!d)
    return NS_ERROR_OUT_OF_MEMORY;

  NS_ADDREF(d);
  nsresult rv = d->QueryInterface(iid, result);
  NS_RELEASE(d);
  return rv;
}