DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=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 "BackgroundFileSaver.h"

#include "ScopedNSSTypes.h"
#include "mozilla/Casting.h"
#include "mozilla/Logging.h"
#include "mozilla/Telemetry.h"
#include "nsCOMArray.h"
#include "nsDependentSubstring.h"
#include "nsIAsyncInputStream.h"
#include "nsIFile.h"
#include "nsIMutableArray.h"
#include "nsIPipe.h"
#include "nsIX509Cert.h"
#include "nsIX509CertDB.h"
#include "nsIX509CertList.h"
#include "nsNetUtil.h"
#include "nsThreadUtils.h"
#include "pk11pub.h"
#include "secoidt.h"

#ifdef XP_WIN
#  include <windows.h>
#  include <softpub.h>
#  include <wintrust.h>
#endif  // XP_WIN

namespace mozilla {
namespace net {

// MOZ_LOG=BackgroundFileSaver:5
static LazyLogModule prlog("BackgroundFileSaver");
#define LOG(args) MOZ_LOG(prlog, mozilla::LogLevel::Debug, args)
#define LOG_ENABLED() MOZ_LOG_TEST(prlog, mozilla::LogLevel::Debug)

////////////////////////////////////////////////////////////////////////////////
//// Globals

/**
 * Buffer size for writing to the output file or reading from the input file.
 */
#define BUFFERED_IO_SIZE (1024 * 32)

/**
 * When this upper limit is reached, the original request is suspended.
 */
#define REQUEST_SUSPEND_AT (1024 * 1024 * 4)

/**
 * When this lower limit is reached, the original request is resumed.
 */
#define REQUEST_RESUME_AT (1024 * 1024 * 2)

////////////////////////////////////////////////////////////////////////////////
//// NotifyTargetChangeRunnable

/**
 * Runnable object used to notify the control thread that file contents will now
 * be saved to the specified file.
 */
class NotifyTargetChangeRunnable final : public Runnable {
 public:
  NotifyTargetChangeRunnable(BackgroundFileSaver* aSaver, nsIFile* aTarget)
      : Runnable("net::NotifyTargetChangeRunnable"),
        mSaver(aSaver),
        mTarget(aTarget) {}

  NS_IMETHOD Run() override { return mSaver->NotifyTargetChange(mTarget); }

 private:
  RefPtr<BackgroundFileSaver> mSaver;
  nsCOMPtr<nsIFile> mTarget;
};

////////////////////////////////////////////////////////////////////////////////
//// BackgroundFileSaver

uint32_t BackgroundFileSaver::sThreadCount = 0;
uint32_t BackgroundFileSaver::sTelemetryMaxThreadCount = 0;

BackgroundFileSaver::BackgroundFileSaver()
    : mControlEventTarget(nullptr),
      mWorkerThread(nullptr),
      mPipeOutputStream(nullptr),
      mPipeInputStream(nullptr),
      mObserver(nullptr),
      mLock("BackgroundFileSaver.mLock"),
      mWorkerThreadAttentionRequested(false),
      mFinishRequested(false),
      mComplete(false),
      mStatus(NS_OK),
      mAppend(false),
      mInitialTarget(nullptr),
      mInitialTargetKeepPartial(false),
      mRenamedTarget(nullptr),
      mRenamedTargetKeepPartial(false),
      mAsyncCopyContext(nullptr),
      mSha256Enabled(false),
      mSignatureInfoEnabled(false),
      mActualTarget(nullptr),
      mActualTargetKeepPartial(false),
      mDigestContext(nullptr) {
  LOG(("Created BackgroundFileSaver [this = %p]", this));
}

BackgroundFileSaver::~BackgroundFileSaver() {
  LOG(("Destroying BackgroundFileSaver [this = %p]", this));
}

// Called on the control thread.
nsresult BackgroundFileSaver::Init() {
  MOZ_ASSERT(NS_IsMainThread(), "This should be called on the main thread");

  nsresult rv;

  rv = NS_NewPipe2(getter_AddRefs(mPipeInputStream),
                   getter_AddRefs(mPipeOutputStream), true, true, 0,
                   HasInfiniteBuffer() ? UINT32_MAX : 0);
  NS_ENSURE_SUCCESS(rv, rv);

  mControlEventTarget = GetCurrentThreadEventTarget();
  NS_ENSURE_TRUE(mControlEventTarget, NS_ERROR_NOT_INITIALIZED);

  rv = NS_NewNamedThread("BgFileSaver", getter_AddRefs(mWorkerThread));
  NS_ENSURE_SUCCESS(rv, rv);

  sThreadCount++;
  if (sThreadCount > sTelemetryMaxThreadCount) {
    sTelemetryMaxThreadCount = sThreadCount;
  }

  return NS_OK;
}

// Called on the control thread.
NS_IMETHODIMP
BackgroundFileSaver::GetObserver(nsIBackgroundFileSaverObserver** aObserver) {
  NS_ENSURE_ARG_POINTER(aObserver);
  *aObserver = mObserver;
  NS_IF_ADDREF(*aObserver);
  return NS_OK;
}

// Called on the control thread.
NS_IMETHODIMP
BackgroundFileSaver::SetObserver(nsIBackgroundFileSaverObserver* aObserver) {
  mObserver = aObserver;
  return NS_OK;
}

// Called on the control thread.
NS_IMETHODIMP
BackgroundFileSaver::EnableAppend() {
  MOZ_ASSERT(NS_IsMainThread(), "This should be called on the main thread");

  MutexAutoLock lock(mLock);
  mAppend = true;

  return NS_OK;
}

// Called on the control thread.
NS_IMETHODIMP
BackgroundFileSaver::SetTarget(nsIFile* aTarget, bool aKeepPartial) {
  NS_ENSURE_ARG(aTarget);
  {
    MutexAutoLock lock(mLock);
    if (!mInitialTarget) {
      aTarget->Clone(getter_AddRefs(mInitialTarget));
      mInitialTargetKeepPartial = aKeepPartial;
    } else {
      aTarget->Clone(getter_AddRefs(mRenamedTarget));
      mRenamedTargetKeepPartial = aKeepPartial;
    }
  }

  // After the worker thread wakes up because attention is requested, it will
  // rename or create the target file as requested, and start copying data.
  return GetWorkerThreadAttention(true);
}

// Called on the control thread.
NS_IMETHODIMP
BackgroundFileSaver::Finish(nsresult aStatus) {
  nsresult rv;

  // This will cause the NS_AsyncCopy operation, if it's in progress, to consume
  // all the data that is still in the pipe, and then finish.
  rv = mPipeOutputStream->Close();
  NS_ENSURE_SUCCESS(rv, rv);

  // Ensure that, when we get attention from the worker thread, if no pending
  // rename operation is waiting, the operation will complete.
  {
    MutexAutoLock lock(mLock);
    mFinishRequested = true;
    if (NS_SUCCEEDED(mStatus)) {
      mStatus = aStatus;
    }
  }

  // After the worker thread wakes up because attention is requested, it will
  // process the completion conditions, detect that completion is requested, and
  // notify the main thread of the completion.  If this function was called with
  // a success code, we wait for the copy to finish before processing the
  // completion conditions, otherwise we interrupt the copy immediately.
  return GetWorkerThreadAttention(NS_FAILED(aStatus));
}

NS_IMETHODIMP
BackgroundFileSaver::EnableSha256() {
  MOZ_ASSERT(NS_IsMainThread(),
             "Can't enable sha256 or initialize NSS off the main thread");
  // Ensure Personal Security Manager is initialized. This is required for
  // PK11_* operations to work.
  nsresult rv;
  nsCOMPtr<nsISupports> nssDummy = do_GetService("@mozilla.org/psm;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  mSha256Enabled = true;
  return NS_OK;
}

NS_IMETHODIMP
BackgroundFileSaver::GetSha256Hash(nsACString& aHash) {
  MOZ_ASSERT(NS_IsMainThread(), "Can't inspect sha256 off the main thread");
  // We acquire a lock because mSha256 is written on the worker thread.
  MutexAutoLock lock(mLock);
  if (mSha256.IsEmpty()) {
    return NS_ERROR_NOT_AVAILABLE;
  }
  aHash = mSha256;
  return NS_OK;
}

NS_IMETHODIMP
BackgroundFileSaver::EnableSignatureInfo() {
  MOZ_ASSERT(NS_IsMainThread(),
             "Can't enable signature extraction off the main thread");
  // Ensure Personal Security Manager is initialized.
  nsresult rv;
  nsCOMPtr<nsISupports> nssDummy = do_GetService("@mozilla.org/psm;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  mSignatureInfoEnabled = true;
  return NS_OK;
}

NS_IMETHODIMP
BackgroundFileSaver::GetSignatureInfo(nsIArray** aSignatureInfo) {
  MOZ_ASSERT(NS_IsMainThread(), "Can't inspect signature off the main thread");
  // We acquire a lock because mSignatureInfo is written on the worker thread.
  MutexAutoLock lock(mLock);
  if (!mComplete || !mSignatureInfoEnabled) {
    return NS_ERROR_NOT_AVAILABLE;
  }
  nsCOMPtr<nsIMutableArray> sigArray = do_CreateInstance(NS_ARRAY_CONTRACTID);
  for (int i = 0; i < mSignatureInfo.Count(); ++i) {
    sigArray->AppendElement(mSignatureInfo[i]);
  }
  *aSignatureInfo = sigArray;
  NS_IF_ADDREF(*aSignatureInfo);
  return NS_OK;
}

// Called on the control thread.
nsresult BackgroundFileSaver::GetWorkerThreadAttention(
    bool aShouldInterruptCopy) {
  nsresult rv;

  MutexAutoLock lock(mLock);

  // We only require attention one time.  If this function is called two times
  // before the worker thread wakes up, and the first has aShouldInterruptCopy
  // false and the second true, we won't forcibly interrupt the copy from the
  // control thread.  However, that never happens, because calling Finish with a
  // success code is the only case that may result in aShouldInterruptCopy being
  // false.  In that case, we won't call this function again, because consumers
  // should not invoke other methods on the control thread after calling Finish.
  // And in any case, Finish already closes one end of the pipe, causing the
  // copy to finish properly on its own.
  if (mWorkerThreadAttentionRequested) {
    return NS_OK;
  }

  if (!mAsyncCopyContext) {
    // Copy is not in progress, post an event to handle the change manually.
    rv = mWorkerThread->Dispatch(
        NewRunnableMethod("net::BackgroundFileSaver::ProcessAttention", this,
                          &BackgroundFileSaver::ProcessAttention),
        NS_DISPATCH_NORMAL);
    NS_ENSURE_SUCCESS(rv, rv);
  } else if (aShouldInterruptCopy) {
    // Interrupt the copy.  The copy will be resumed, if needed, by the
    // ProcessAttention function, invoked by the AsyncCopyCallback function.
    NS_CancelAsyncCopy(mAsyncCopyContext, NS_ERROR_ABORT);
  }

  // Indicate that attention has been requested successfully, there is no need
  // to post another event until the worker thread processes the current one.
  mWorkerThreadAttentionRequested = true;

  return NS_OK;
}

// Called on the worker thread.
// static
void BackgroundFileSaver::AsyncCopyCallback(void* aClosure, nsresult aStatus) {
  // We called NS_ADDREF_THIS when NS_AsyncCopy started, to keep the object
  // alive even if other references disappeared.  At the end of this method,
  // we've finished using the object and can safely release our reference.
  RefPtr<BackgroundFileSaver> self =
      dont_AddRef((BackgroundFileSaver*)aClosure);
  {
    MutexAutoLock lock(self->mLock);

    // Now that the copy was interrupted or terminated, any notification from
    // the control thread requires an event to be posted to the worker thread.
    self->mAsyncCopyContext = nullptr;

    // When detecting failures, ignore the status code we use to interrupt.
    if (NS_FAILED(aStatus) && aStatus != NS_ERROR_ABORT &&
        NS_SUCCEEDED(self->mStatus)) {
      self->mStatus = aStatus;
    }
  }

  (void)self->ProcessAttention();
}

// Called on the worker thread.
nsresult BackgroundFileSaver::ProcessAttention() {
  nsresult rv;

  // This function is called whenever the attention of the worker thread has
  // been requested.  This may happen in these cases:
  // * We are about to start the copy for the first time.  In this case, we are
  //   called from an event posted on the worker thread from the control thread
  //   by GetWorkerThreadAttention, and mAsyncCopyContext is null.
  // * We have interrupted the copy for some reason.  In this case, we are
  //   called by AsyncCopyCallback, and mAsyncCopyContext is null.
  // * We are currently executing ProcessStateChange, and attention is requested
  //   by the control thread, for example because SetTarget or Finish have been
  //   called.  In this case, we are called from from an event posted through
  //   GetWorkerThreadAttention.  While mAsyncCopyContext was always null when
  //   the event was posted, at this point mAsyncCopyContext may not be null
  //   anymore, because ProcessStateChange may have started the copy before the
  //   event that called this function was processed on the worker thread.
  // If mAsyncCopyContext is not null, we interrupt the copy and re-enter
  // through AsyncCopyCallback.  This allows us to check if, for instance, we
  // should rename the target file.  We will then restart the copy if needed.
  if (mAsyncCopyContext) {
    NS_CancelAsyncCopy(mAsyncCopyContext, NS_ERROR_ABORT);
    return NS_OK;
  }
  // Use the current shared state to determine the next operation to execute.
  rv = ProcessStateChange();
  if (NS_FAILED(rv)) {
    // If something failed while processing, terminate the operation now.
    {
      MutexAutoLock lock(mLock);

      if (NS_SUCCEEDED(mStatus)) {
        mStatus = rv;
      }
    }
    // Ensure we notify completion now that the operation failed.
    CheckCompletion();
  }

  return NS_OK;
}

// Called on the worker thread.
nsresult BackgroundFileSaver::ProcessStateChange() {
  nsresult rv;

  // We might have been notified because the operation is complete, verify.
  if (CheckCompletion()) {
    return NS_OK;
  }

  // Get a copy of the current shared state for the worker thread.
  nsCOMPtr<nsIFile> initialTarget;
  bool initialTargetKeepPartial;
  nsCOMPtr<nsIFile> renamedTarget;
  bool renamedTargetKeepPartial;
  bool sha256Enabled;
  bool append;
  {
    MutexAutoLock lock(mLock);

    initialTarget = mInitialTarget;
    initialTargetKeepPartial = mInitialTargetKeepPartial;
    renamedTarget = mRenamedTarget;
    renamedTargetKeepPartial = mRenamedTargetKeepPartial;
    sha256Enabled = mSha256Enabled;
    append = mAppend;

    // From now on, another attention event needs to be posted if state changes.
    mWorkerThreadAttentionRequested = false;
  }

  // The initial target can only be null if it has never been assigned.  In this
  // case, there is nothing to do since we never created any output file.
  if (!initialTarget) {
    return NS_OK;
  }

  // Determine if we are processing the attention request for the first time.
  bool isContinuation = !!mActualTarget;
  if (!isContinuation) {
    // Assign the target file for the first time.
    mActualTarget = initialTarget;
    mActualTargetKeepPartial = initialTargetKeepPartial;
  }

  // Verify whether we have actually been instructed to use a different file.
  // This may happen the first time this function is executed, if SetTarget was
  // called two times before the worker thread processed the attention request.
  bool equalToCurrent = false;
  if (renamedTarget) {
    rv = mActualTarget->Equals(renamedTarget, &equalToCurrent);
    NS_ENSURE_SUCCESS(rv, rv);
    if (!equalToCurrent) {
      // If we were asked to rename the file but the initial file did not exist,
      // we simply create the file in the renamed location.  We avoid this check
      // if we have already started writing the output file ourselves.
      bool exists = true;
      if (!isContinuation) {
        rv = mActualTarget->Exists(&exists);
        NS_ENSURE_SUCCESS(rv, rv);
      }
      if (exists) {
        // We are moving the previous target file to a different location.
        nsCOMPtr<nsIFile> renamedTargetParentDir;
        rv = renamedTarget->GetParent(getter_AddRefs(renamedTargetParentDir));
        NS_ENSURE_SUCCESS(rv, rv);

        nsAutoString renamedTargetName;
        rv = renamedTarget->GetLeafName(renamedTargetName);
        NS_ENSURE_SUCCESS(rv, rv);

        // We must delete any existing target file before moving the current
        // one.
        rv = renamedTarget->Exists(&exists);
        NS_ENSURE_SUCCESS(rv, rv);
        if (exists) {
          rv = renamedTarget->Remove(false);
          NS_ENSURE_SUCCESS(rv, rv);
        }

        // Move the file.  If this fails, we still reference the original file
        // in mActualTarget, so that it is deleted if requested.  If this
        // succeeds, the nsIFile instance referenced by mActualTarget mutates
        // and starts pointing to the new file, but we'll discard the reference.
        rv = mActualTarget->MoveTo(renamedTargetParentDir, renamedTargetName);
        NS_ENSURE_SUCCESS(rv, rv);
      }

      // We should not only update the mActualTarget with renameTarget when
      // they point to the different files.
      // In this way, if mActualTarget and renamedTarget point to the same file
      // with different addresses, "CheckCompletion()" will return false
      // forever.
    }

    // Update mActualTarget with renameTarget,
    // even if they point to the same file.
    mActualTarget = renamedTarget;
    mActualTargetKeepPartial = renamedTargetKeepPartial;
  }

  // Notify if the target file name actually changed.
  if (!equalToCurrent) {
    // We must clone the nsIFile instance because mActualTarget is not
    // immutable, it may change if the target is renamed later.
    nsCOMPtr<nsIFile> actualTargetToNotify;
    rv = mActualTarget->Clone(getter_AddRefs(actualTargetToNotify));
    NS_ENSURE_SUCCESS(rv, rv);

    RefPtr<NotifyTargetChangeRunnable> event =
        new NotifyTargetChangeRunnable(this, actualTargetToNotify);
    NS_ENSURE_TRUE(event, NS_ERROR_FAILURE);

    rv = mControlEventTarget->Dispatch(event, NS_DISPATCH_NORMAL);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  if (isContinuation) {
    // The pending rename operation might be the last task before finishing. We
    // may return here only if we have already created the target file.
    if (CheckCompletion()) {
      return NS_OK;
    }

    // Even if the operation did not complete, the pipe input stream may be
    // empty and may have been closed already.  We detect this case using the
    // Available property, because it never returns an error if there is more
    // data to be consumed.  If the pipe input stream is closed, we just exit
    // and wait for more calls like SetTarget or Finish to be invoked on the
    // control thread.  However, we still truncate the file or create the
    // initial digest context if we are expected to do that.
    uint64_t available;
    rv = mPipeInputStream->Available(&available);
    if (NS_FAILED(rv)) {
      return NS_OK;
    }
  }

  // Create the digest context if requested and NSS hasn't been shut down.
  if (sha256Enabled && !mDigestContext) {
    mDigestContext =
        UniquePK11Context(PK11_CreateDigestContext(SEC_OID_SHA256));
    NS_ENSURE_TRUE(mDigestContext, NS_ERROR_OUT_OF_MEMORY);
  }

  // When we are requested to append to an existing file, we should read the
  // existing data and ensure we include it as part of the final hash.
  if (mDigestContext && append && !isContinuation) {
    nsCOMPtr<nsIInputStream> inputStream;
    rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), mActualTarget,
                                    PR_RDONLY | nsIFile::OS_READAHEAD);
    if (rv != NS_ERROR_FILE_NOT_FOUND) {
      NS_ENSURE_SUCCESS(rv, rv);

      char buffer[BUFFERED_IO_SIZE];
      while (true) {
        uint32_t count;
        rv = inputStream->Read(buffer, BUFFERED_IO_SIZE, &count);
        NS_ENSURE_SUCCESS(rv, rv);

        if (count == 0) {
          // We reached the end of the file.
          break;
        }

        nsresult rv = MapSECStatus(
            PK11_DigestOp(mDigestContext.get(),
                          BitwiseCast<unsigned char*, char*>(buffer), count));
        NS_ENSURE_SUCCESS(rv, rv);
      }

      rv = inputStream->Close();
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }

  // We will append to the initial target file only if it was requested by the
  // caller, but we'll always append on subsequent accesses to the target file.
  int32_t creationIoFlags;
  if (isContinuation) {
    creationIoFlags = PR_APPEND;
  } else {
    creationIoFlags = (append ? PR_APPEND : PR_TRUNCATE) | PR_CREATE_FILE;
  }

  // Create the target file, or append to it if we already started writing it.
  // The 0600 permissions are used while the file is being downloaded, and for
  // interrupted downloads. Those may be located in the system temporary
  // directory, as well as the target directory, and generally have a ".part"
  // extension. Those part files should never be group or world-writable even
  // if the umask allows it.
  nsCOMPtr<nsIOutputStream> outputStream;
  rv = NS_NewLocalFileOutputStream(getter_AddRefs(outputStream), mActualTarget,
                                   PR_WRONLY | creationIoFlags, 0600);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIOutputStream> bufferedStream;
  rv = NS_NewBufferedOutputStream(getter_AddRefs(bufferedStream),
                                  outputStream.forget(), BUFFERED_IO_SIZE);
  NS_ENSURE_SUCCESS(rv, rv);
  outputStream = bufferedStream;

  // Wrap the output stream so that it feeds the digest context if needed.
  if (mDigestContext) {
    // Constructing the DigestOutputStream cannot fail. Passing mDigestContext
    // to DigestOutputStream is safe, because BackgroundFileSaver always
    // outlives the outputStream. BackgroundFileSaver is reference-counted
    // before the call to AsyncCopy, and mDigestContext is never destroyed
    // before AsyncCopyCallback.
    outputStream = new DigestOutputStream(outputStream, mDigestContext.get());
  }

  // Start copying our input to the target file.  No errors can be raised past
  // this point if the copy starts, since they should be handled by the thread.
  {
    MutexAutoLock lock(mLock);

    rv = NS_AsyncCopy(mPipeInputStream, outputStream, mWorkerThread,
                      NS_ASYNCCOPY_VIA_READSEGMENTS, 4096, AsyncCopyCallback,
                      this, false, true, getter_AddRefs(mAsyncCopyContext),
                      GetProgressCallback());
    if (NS_FAILED(rv)) {
      NS_WARNING("NS_AsyncCopy failed.");
      mAsyncCopyContext = nullptr;
      return rv;
    }
  }

  // If the operation succeeded, we must ensure that we keep this object alive
  // for the entire duration of the copy, since only the raw pointer will be
  // provided as the argument of the AsyncCopyCallback function.  We can add the
  // reference now, after NS_AsyncCopy returned, because it always starts
  // processing asynchronously, and there is no risk that the callback is
  // invoked before we reach this point.  If the operation failed instead, then
  // AsyncCopyCallback will never be called.
  NS_ADDREF_THIS();

  return NS_OK;
}

// Called on the worker thread.
bool BackgroundFileSaver::CheckCompletion() {
  nsresult rv;

  MOZ_ASSERT(!mAsyncCopyContext,
             "Should not be copying when checking completion conditions.");

  bool failed = true;
  {
    MutexAutoLock lock(mLock);

    if (mComplete) {
      return true;
    }

    // If an error occurred, we don't need to do the checks in this code block,
    // and the operation can be completed immediately with a failure code.
    if (NS_SUCCEEDED(mStatus)) {
      failed = false;

      // We did not incur in an error, so we must determine if we can stop now.
      // If the Finish method has not been called, we can just continue now.
      if (!mFinishRequested) {
        return false;
      }

      // We can only stop when all the operations requested by the control
      // thread have been processed.  First, we check whether we have processed
      // the first SetTarget call, if any.  Then, we check whether we have
      // processed any rename requested by subsequent SetTarget calls.
      if ((mInitialTarget && !mActualTarget) ||
          (mRenamedTarget && mRenamedTarget != mActualTarget)) {
        return false;
      }

      // If we still have data to write to the output file, allow the copy
      // operation to resume.  The Available getter may return an error if one
      // of the pipe's streams has been already closed.
      uint64_t available;
      rv = mPipeInputStream->Available(&available);
      if (NS_SUCCEEDED(rv) && available != 0) {
        return false;
      }
    }

    mComplete = true;
  }

  // Ensure we notify completion now that the operation finished.
  // Do a best-effort attempt to remove the file if required.
  if (failed && mActualTarget && !mActualTargetKeepPartial) {
    (void)mActualTarget->Remove(false);
  }

  // Finish computing the hash
  if (!failed && mDigestContext) {
    Digest d;
    rv = d.End(SEC_OID_SHA256, mDigestContext);
    if (NS_SUCCEEDED(rv)) {
      MutexAutoLock lock(mLock);
      mSha256 = nsDependentCSubstring(
          BitwiseCast<char*, unsigned char*>(d.get().data), d.get().len);
    }
  }

  // Compute the signature of the binary. ExtractSignatureInfo doesn't do
  // anything on non-Windows platforms except return an empty nsIArray.
  if (!failed && mActualTarget) {
    nsString filePath;
    mActualTarget->GetTarget(filePath);
    nsresult rv = ExtractSignatureInfo(filePath);
    if (NS_FAILED(rv)) {
      LOG(("Unable to extract signature information [this = %p].", this));
    } else {
      LOG(("Signature extraction success! [this = %p]", this));
    }
  }

  // Post an event to notify that the operation completed.
  if (NS_FAILED(mControlEventTarget->Dispatch(
          NewRunnableMethod("BackgroundFileSaver::NotifySaveComplete", this,
                            &BackgroundFileSaver::NotifySaveComplete),
          NS_DISPATCH_NORMAL))) {
    NS_WARNING("Unable to post completion event to the control thread.");
  }

  return true;
}

// Called on the control thread.
nsresult BackgroundFileSaver::NotifyTargetChange(nsIFile* aTarget) {
  if (mObserver) {
    (void)mObserver->OnTargetChange(this, aTarget);
  }

  return NS_OK;
}

// Called on the control thread.
nsresult BackgroundFileSaver::NotifySaveComplete() {
  MOZ_ASSERT(NS_IsMainThread(), "This should be called on the main thread");

  nsresult status;
  {
    MutexAutoLock lock(mLock);
    status = mStatus;
  }

  if (mObserver) {
    (void)mObserver->OnSaveComplete(this, status);
    // If mObserver keeps alive an enclosure that captures `this`, we'll have a
    // cycle that won't be caught by the cycle-collector, so we need to break it
    // when we're done here (see bug 1444265).
    mObserver = nullptr;
  }

  // At this point, the worker thread will not process any more events, and we
  // can shut it down.  Shutting down a thread may re-enter the event loop on
  // this thread.  This is not a problem in this case, since this function is
  // called by a top-level event itself, and we have already invoked the
  // completion observer callback.  Re-entering the loop can only delay the
  // final release and destruction of this saver object, since we are keeping a
  // reference to it through the event object.
  mWorkerThread->Shutdown();

  sThreadCount--;

  // When there are no more active downloads, we consider the download session
  // finished. We record the maximum number of concurrent downloads reached
  // during the session in a telemetry histogram, and we reset the maximum
  // thread counter for the next download session
  if (sThreadCount == 0) {
    Telemetry::Accumulate(Telemetry::BACKGROUNDFILESAVER_THREAD_COUNT,
                          sTelemetryMaxThreadCount);
    sTelemetryMaxThreadCount = 0;
  }

  return NS_OK;
}

nsresult BackgroundFileSaver::ExtractSignatureInfo(const nsAString& filePath) {
  MOZ_ASSERT(!NS_IsMainThread(), "Cannot extract signature on main thread");
  {
    MutexAutoLock lock(mLock);
    if (!mSignatureInfoEnabled) {
      return NS_OK;
    }
  }
  nsresult rv;
  nsCOMPtr<nsIX509CertDB> certDB = do_GetService(NS_X509CERTDB_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);
#ifdef XP_WIN
  // Setup the file to check.
  WINTRUST_FILE_INFO fileToCheck = {0};
  fileToCheck.cbStruct = sizeof(WINTRUST_FILE_INFO);
  fileToCheck.pcwszFilePath = filePath.Data();
  fileToCheck.hFile = nullptr;
  fileToCheck.pgKnownSubject = nullptr;

  // We want to check it is signed and trusted.
  WINTRUST_DATA trustData = {0};
  trustData.cbStruct = sizeof(trustData);
  trustData.pPolicyCallbackData = nullptr;
  trustData.pSIPClientData = nullptr;
  trustData.dwUIChoice = WTD_UI_NONE;
  trustData.fdwRevocationChecks = WTD_REVOKE_NONE;
  trustData.dwUnionChoice = WTD_CHOICE_FILE;
  trustData.dwStateAction = WTD_STATEACTION_VERIFY;
  trustData.hWVTStateData = nullptr;
  trustData.pwszURLReference = nullptr;
  // Disallow revocation checks over the network
  trustData.dwProvFlags = WTD_CACHE_ONLY_URL_RETRIEVAL;
  // no UI
  trustData.dwUIContext = 0;
  trustData.pFile = &fileToCheck;

  // The WINTRUST_ACTION_GENERIC_VERIFY_V2 policy verifies that the certificate
  // chains up to a trusted root CA and has appropriate permissions to sign
  // code.
  GUID policyGUID = WINTRUST_ACTION_GENERIC_VERIFY_V2;
  // Check if the file is signed by something that is trusted. If the file is
  // not signed, this is a no-op.
  LONG ret = WinVerifyTrust(nullptr, &policyGUID, &trustData);
  CRYPT_PROVIDER_DATA* cryptoProviderData = nullptr;
  // According to the Windows documentation, we should check against 0 instead
  // of ERROR_SUCCESS, which is an HRESULT.
  if (ret == 0) {
    cryptoProviderData = WTHelperProvDataFromStateData(trustData.hWVTStateData);
  }
  if (cryptoProviderData) {
    // Lock because signature information is read on the main thread.
    MutexAutoLock lock(mLock);
    LOG(("Downloaded trusted and signed file [this = %p].", this));
    // A binary may have multiple signers. Each signer may have multiple certs
    // in the chain.
    for (DWORD i = 0; i < cryptoProviderData->csSigners; ++i) {
      const CERT_CHAIN_CONTEXT* certChainContext =
          cryptoProviderData->pasSigners[i].pChainContext;
      if (!certChainContext) {
        break;
      }
      for (DWORD j = 0; j < certChainContext->cChain; ++j) {
        const CERT_SIMPLE_CHAIN* certSimpleChain =
            certChainContext->rgpChain[j];
        if (!certSimpleChain) {
          break;
        }
        nsCOMPtr<nsIX509CertList> nssCertList =
            do_CreateInstance(NS_X509CERTLIST_CONTRACTID);
        if (!nssCertList) {
          break;
        }
        bool extractionSuccess = true;
        for (DWORD k = 0; k < certSimpleChain->cElement; ++k) {
          CERT_CHAIN_ELEMENT* certChainElement = certSimpleChain->rgpElement[k];
          if (certChainElement->pCertContext->dwCertEncodingType !=
              X509_ASN_ENCODING) {
            continue;
          }
          nsCOMPtr<nsIX509Cert> nssCert = nullptr;
          nsDependentCSubstring certDER(
              reinterpret_cast<char*>(
                  certChainElement->pCertContext->pbCertEncoded),
              certChainElement->pCertContext->cbCertEncoded);
          rv = certDB->ConstructX509(certDER, getter_AddRefs(nssCert));
          if (!nssCert) {
            extractionSuccess = false;
            LOG(("Couldn't create NSS cert [this = %p]", this));
            break;
          }
          rv = nssCertList->AddCert(nssCert);
          if (NS_FAILED(rv)) {
            extractionSuccess = false;
            LOG(("Couldn't add NSS cert to cert list [this = %p]", this));
            break;
          }
          nsString subjectName;
          nssCert->GetSubjectName(subjectName);
          LOG(("Adding cert %s [this = %p]",
               NS_ConvertUTF16toUTF8(subjectName).get(), this));
        }
        if (extractionSuccess) {
          mSignatureInfo.AppendObject(nssCertList);
        }
      }
    }
    // Free the provider data if cryptoProviderData is not null.
    trustData.dwStateAction = WTD_STATEACTION_CLOSE;
    WinVerifyTrust(nullptr, &policyGUID, &trustData);
  } else {
    LOG(("Downloaded unsigned or untrusted file [this = %p].", this));
  }
#endif
  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// BackgroundFileSaverOutputStream

NS_IMPL_ISUPPORTS(BackgroundFileSaverOutputStream, nsIBackgroundFileSaver,
                  nsIOutputStream, nsIAsyncOutputStream,
                  nsIOutputStreamCallback)

BackgroundFileSaverOutputStream::BackgroundFileSaverOutputStream()
    : BackgroundFileSaver(), mAsyncWaitCallback(nullptr) {}

bool BackgroundFileSaverOutputStream::HasInfiniteBuffer() { return false; }

nsAsyncCopyProgressFun BackgroundFileSaverOutputStream::GetProgressCallback() {
  return nullptr;
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::Close() { return mPipeOutputStream->Close(); }

NS_IMETHODIMP
BackgroundFileSaverOutputStream::Flush() { return mPipeOutputStream->Flush(); }

NS_IMETHODIMP
BackgroundFileSaverOutputStream::Write(const char* aBuf, uint32_t aCount,
                                       uint32_t* _retval) {
  return mPipeOutputStream->Write(aBuf, aCount, _retval);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::WriteFrom(nsIInputStream* aFromStream,
                                           uint32_t aCount, uint32_t* _retval) {
  return mPipeOutputStream->WriteFrom(aFromStream, aCount, _retval);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::WriteSegments(nsReadSegmentFun aReader,
                                               void* aClosure, uint32_t aCount,
                                               uint32_t* _retval) {
  return mPipeOutputStream->WriteSegments(aReader, aClosure, aCount, _retval);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::IsNonBlocking(bool* _retval) {
  return mPipeOutputStream->IsNonBlocking(_retval);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::CloseWithStatus(nsresult reason) {
  return mPipeOutputStream->CloseWithStatus(reason);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::AsyncWait(nsIOutputStreamCallback* aCallback,
                                           uint32_t aFlags,
                                           uint32_t aRequestedCount,
                                           nsIEventTarget* aEventTarget) {
  NS_ENSURE_STATE(!mAsyncWaitCallback);

  mAsyncWaitCallback = aCallback;

  return mPipeOutputStream->AsyncWait(this, aFlags, aRequestedCount,
                                      aEventTarget);
}

NS_IMETHODIMP
BackgroundFileSaverOutputStream::OnOutputStreamReady(
    nsIAsyncOutputStream* aStream) {
  NS_ENSURE_STATE(mAsyncWaitCallback);

  nsCOMPtr<nsIOutputStreamCallback> asyncWaitCallback = nullptr;
  asyncWaitCallback.swap(mAsyncWaitCallback);

  return asyncWaitCallback->OnOutputStreamReady(this);
}

////////////////////////////////////////////////////////////////////////////////
//// BackgroundFileSaverStreamListener

NS_IMPL_ISUPPORTS(BackgroundFileSaverStreamListener, nsIBackgroundFileSaver,
                  nsIRequestObserver, nsIStreamListener)

BackgroundFileSaverStreamListener::BackgroundFileSaverStreamListener()
    : BackgroundFileSaver(),
      mSuspensionLock("BackgroundFileSaverStreamListener.mSuspensionLock"),
      mReceivedTooMuchData(false),
      mRequest(nullptr),
      mRequestSuspended(false) {}

bool BackgroundFileSaverStreamListener::HasInfiniteBuffer() { return true; }

nsAsyncCopyProgressFun
BackgroundFileSaverStreamListener::GetProgressCallback() {
  return AsyncCopyProgressCallback;
}

NS_IMETHODIMP
BackgroundFileSaverStreamListener::OnStartRequest(nsIRequest* aRequest) {
  NS_ENSURE_ARG(aRequest);

  return NS_OK;
}

NS_IMETHODIMP
BackgroundFileSaverStreamListener::OnStopRequest(nsIRequest* aRequest,
                                                 nsresult aStatusCode) {
  // If an error occurred, cancel the operation immediately.  On success, wait
  // until the caller has determined whether the file should be renamed.
  if (NS_FAILED(aStatusCode)) {
    Finish(aStatusCode);
  }

  return NS_OK;
}

NS_IMETHODIMP
BackgroundFileSaverStreamListener::OnDataAvailable(nsIRequest* aRequest,
                                                   nsIInputStream* aInputStream,
                                                   uint64_t aOffset,
                                                   uint32_t aCount) {
  nsresult rv;

  NS_ENSURE_ARG(aRequest);

  // Read the requested data.  Since the pipe has an infinite buffer, we don't
  // expect any write error to occur here.
  uint32_t writeCount;
  rv = mPipeOutputStream->WriteFrom(aInputStream, aCount, &writeCount);
  NS_ENSURE_SUCCESS(rv, rv);

  // If reading from the input stream fails for any reason, the pipe will return
  // a success code, but without reading all the data.  Since we should be able
  // to read the requested data when OnDataAvailable is called, raise an error.
  if (writeCount < aCount) {
    NS_WARNING("Reading from the input stream should not have failed.");
    return NS_ERROR_UNEXPECTED;
  }

  bool stateChanged = false;
  {
    MutexAutoLock lock(mSuspensionLock);

    if (!mReceivedTooMuchData) {
      uint64_t available;
      nsresult rv = mPipeInputStream->Available(&available);
      if (NS_SUCCEEDED(rv) && available > REQUEST_SUSPEND_AT) {
        mReceivedTooMuchData = true;
        mRequest = aRequest;
        stateChanged = true;
      }
    }
  }

  if (stateChanged) {
    NotifySuspendOrResume();
  }

  return NS_OK;
}

// Called on the worker thread.
// static
void BackgroundFileSaverStreamListener::AsyncCopyProgressCallback(
    void* aClosure, uint32_t aCount) {
  BackgroundFileSaverStreamListener* self =
      (BackgroundFileSaverStreamListener*)aClosure;

  // Wait if the control thread is in the process of suspending or resuming.
  MutexAutoLock lock(self->mSuspensionLock);

  // This function is called when some bytes are consumed by NS_AsyncCopy.  Each
  // time this happens, verify if a suspended request should be resumed, because
  // we have now consumed enough data.
  if (self->mReceivedTooMuchData) {
    uint64_t available;
    nsresult rv = self->mPipeInputStream->Available(&available);
    if (NS_FAILED(rv) || available < REQUEST_RESUME_AT) {
      self->mReceivedTooMuchData = false;

      // Post an event to verify if the request should be resumed.
      if (NS_FAILED(self->mControlEventTarget->Dispatch(
              NewRunnableMethod(
                  "BackgroundFileSaverStreamListener::NotifySuspendOrResume",
                  self,
                  &BackgroundFileSaverStreamListener::NotifySuspendOrResume),
              NS_DISPATCH_NORMAL))) {
        NS_WARNING("Unable to post resume event to the control thread.");
      }
    }
  }
}

// Called on the control thread.
nsresult BackgroundFileSaverStreamListener::NotifySuspendOrResume() {
  // Prevent the worker thread from changing state while processing.
  MutexAutoLock lock(mSuspensionLock);

  if (mReceivedTooMuchData) {
    if (!mRequestSuspended) {
      // Try to suspend the request.  If this fails, don't try to resume later.
      if (NS_SUCCEEDED(mRequest->Suspend())) {
        mRequestSuspended = true;
      } else {
        NS_WARNING("Unable to suspend the request.");
      }
    }
  } else {
    if (mRequestSuspended) {
      // Resume the request only if we succeeded in suspending it.
      if (NS_SUCCEEDED(mRequest->Resume())) {
        mRequestSuspended = false;
      } else {
        NS_WARNING("Unable to resume the request.");
      }
    }
  }

  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// DigestOutputStream
NS_IMPL_ISUPPORTS(DigestOutputStream, nsIOutputStream)

DigestOutputStream::DigestOutputStream(nsIOutputStream* aStream,
                                       PK11Context* aContext)
    : mOutputStream(aStream), mDigestContext(aContext) {
  MOZ_ASSERT(mDigestContext, "Can't have null digest context");
  MOZ_ASSERT(mOutputStream, "Can't have null output stream");
}

NS_IMETHODIMP
DigestOutputStream::Close() { return mOutputStream->Close(); }

NS_IMETHODIMP
DigestOutputStream::Flush() { return mOutputStream->Flush(); }

NS_IMETHODIMP
DigestOutputStream::Write(const char* aBuf, uint32_t aCount, uint32_t* retval) {
  nsresult rv = MapSECStatus(PK11_DigestOp(
      mDigestContext, BitwiseCast<const unsigned char*, const char*>(aBuf),
      aCount));
  NS_ENSURE_SUCCESS(rv, rv);

  return mOutputStream->Write(aBuf, aCount, retval);
}

NS_IMETHODIMP
DigestOutputStream::WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
                              uint32_t* retval) {
  // Not supported. We could read the stream to a buf, call DigestOp on the
  // result, seek back and pass the stream on, but it's not worth it since our
  // application (NS_AsyncCopy) doesn't invoke this on the sink.
  MOZ_CRASH("DigestOutputStream::WriteFrom not implemented");
}

NS_IMETHODIMP
DigestOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
                                  uint32_t aCount, uint32_t* retval) {
  MOZ_CRASH("DigestOutputStream::WriteSegments not implemented");
}

NS_IMETHODIMP
DigestOutputStream::IsNonBlocking(bool* retval) {
  return mOutputStream->IsNonBlocking(retval);
}

#undef LOG_ENABLED

}  // namespace net
}  // namespace mozilla