Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

1 files changed, 597 insertions, 0 deletions

diff --git a/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp b/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp
new file mode 100644
index 0000000000..20b55ea150
--- /dev/null
+++ b/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp
@@ -0,0 +1,597 @@
+/* -*- 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 "nsUrlClassifierPrefixSet.h"
+#include "nsIUrlClassifierPrefixSet.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsTArray.h"
+#include "nsString.h"
+#include "mozilla/Logging.h"
+#include "mozilla/StaticPrefs_browser.h"
+
+using namespace mozilla;
+
+// MOZ_LOG=UrlClassifierPrefixSet:5
+static LazyLogModule gUrlClassifierPrefixSetLog("UrlClassifierPrefixSet");
+#define LOG(args) \
+  MOZ_LOG(gUrlClassifierPrefixSetLog, mozilla::LogLevel::Debug, args)
+#define LOG_ENABLED() \
+  MOZ_LOG_TEST(gUrlClassifierPrefixSetLog, mozilla::LogLevel::Debug)
+
+NS_IMPL_ISUPPORTS(nsUrlClassifierPrefixSet, nsIUrlClassifierPrefixSet)
+
+nsUrlClassifierPrefixSet::nsUrlClassifierPrefixSet()
+    : mLock("nsUrlClassifierPrefixSet.mLock"), mTotalPrefixes(0) {}
+
+NS_IMETHODIMP
+nsUrlClassifierPrefixSet::Init(const nsACString& aName) {
+  mName = aName;
+
+  return NS_OK;
+}
+
+nsUrlClassifierPrefixSet::~nsUrlClassifierPrefixSet() {
+  for (uint32_t i = 0; i < mIndexDeltas.Length(); i++) {
+    mIndexDeltas[i].Clear();
+  }
+  mIndexDeltas.Clear();
+  mIndexPrefixes.Clear();
+}
+
+void nsUrlClassifierPrefixSet::Clear() {
+  LOG(("[%s] Clearing PrefixSet", mName.get()));
+  mIndexDeltas.Clear();
+  mIndexPrefixes.Clear();
+  mTotalPrefixes = 0;
+}
+
+NS_IMETHODIMP
+nsUrlClassifierPrefixSet::SetPrefixes(const uint32_t* aArray,
+                                      uint32_t aLength) {
+  MutexAutoLock lock(mLock);
+
+  nsresult rv = NS_OK;
+  Clear();
+
+  if (aLength > 0) {
+    rv = MakePrefixSet(aArray, aLength);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      Clear();  // clear out any leftovers
+    }
+  }
+
+  MOZ_ASSERT_IF(mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mTotalPrefixes);
+  MOZ_ASSERT_IF(!mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mIndexDeltas.Length());
+  return rv;
+}
+
+nsresult nsUrlClassifierPrefixSet::MakePrefixSet(const uint32_t* aPrefixes,
+                                                 uint32_t aLength) {
+  mLock.AssertCurrentThreadOwns();
+
+  MOZ_ASSERT(aPrefixes);
+  MOZ_ASSERT(aLength > 0);
+
+#ifdef DEBUG
+  for (uint32_t i = 1; i < aLength; i++) {
+    MOZ_ASSERT(aPrefixes[i] >= aPrefixes[i - 1]);
+  }
+#endif
+
+  uint32_t totalDeltas = 0;
+
+  // Request one memory space to store all the prefixes may lead to
+  // memory allocation failure on certain platforms(See Bug 1046038).
+  // So if required size to store all the prefixes exceeds defined
+  // threshold(512k), we divide prefixes into delta chunks instead. Note that
+  // the potential overhead of this approach is that it may reuqire more memory
+  // compared to store all prefixes in one array because of jemalloc's
+  // implementation.
+  if (aLength * sizeof(uint32_t) <
+      StaticPrefs::browser_safebrowsing_prefixset_max_array_size()) {
+    // Not over the threshold, store all prefixes into mIndexPrefixes.
+    // mIndexDeltas is empty in this case.
+    mIndexPrefixes.SetCapacity(aLength);
+    for (uint32_t i = 0; i < aLength; i++) {
+      mIndexPrefixes.AppendElement(aPrefixes[i]);
+    }
+  } else {
+    // Apply delta algorithm to split prefixes into smaller delta chunk.
+
+    // We estimate the capacity of mIndexPrefixes & mIndexDeltas by assuming
+    // each element in mIndexDeltas stores DELTAS_LIMITS deltas, so the
+    // number of indexed prefixes is round up of
+    // TotalPrefixes / (DELTA_LIMIT + 1)
+    // The estimation only works when the number of prefixes are over a
+    // certain limit, which means, arrays in mIndexDeltas are always full.
+    uint32_t estimateCapacity =
+        (aLength + (DELTAS_LIMIT + 1) - 1) / (DELTAS_LIMIT + 1);
+    mIndexPrefixes.SetCapacity(estimateCapacity);
+    mIndexDeltas.SetCapacity(estimateCapacity);
+
+    mIndexPrefixes.AppendElement(aPrefixes[0]);
+    mIndexDeltas.AppendElement();
+    mIndexDeltas.LastElement().SetCapacity(DELTAS_LIMIT);
+
+    uint32_t numOfDeltas = 0;
+    uint32_t previousItem = aPrefixes[0];
+    for (uint32_t i = 1; i < aLength; i++) {
+      if ((numOfDeltas >= DELTAS_LIMIT) ||
+          (aPrefixes[i] - previousItem >= MAX_INDEX_DIFF)) {
+        // Compact the previous element.
+        // Note there is always at least one element when we get here,
+        // because we created the first element before the loop.
+        mIndexDeltas.LastElement().Compact();
+        if (!mIndexDeltas.AppendElement(fallible)) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+        mIndexDeltas.LastElement().SetCapacity(DELTAS_LIMIT);
+
+        if (!mIndexPrefixes.AppendElement(aPrefixes[i], fallible)) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+
+        numOfDeltas = 0;
+      } else {
+        uint16_t delta = aPrefixes[i] - previousItem;
+        if (!mIndexDeltas.LastElement().AppendElement(delta, fallible)) {
+          return NS_ERROR_OUT_OF_MEMORY;
+        }
+
+        numOfDeltas++;
+        totalDeltas++;
+      }
+      previousItem = aPrefixes[i];
+    }
+
+    mIndexDeltas.LastElement().Compact();
+    mIndexDeltas.Compact();
+    mIndexPrefixes.Compact();
+
+    MOZ_ASSERT(mIndexPrefixes.Length() == mIndexDeltas.Length());
+  }
+
+  if (totalDeltas == 0) {
+    // We have to clear mIndexDeltas here because it is still possible
+    // that the delta generation algorithm produces no deltas at all. When that
+    // happens, mIndexDeltas is not empty, which conflicts with the assumption
+    // that when there is no delta, mIndexDeltas is empty.
+    mIndexDeltas.Clear();
+  }
+  mTotalPrefixes = aLength;
+
+  LOG(("Total number of indices: %d", aLength));
+  LOG(("Total number of deltas: %d", totalDeltas));
+  LOG(("Total number of delta chunks: %zu", mIndexDeltas.Length()));
+
+  return NS_OK;
+}
+
+nsresult nsUrlClassifierPrefixSet::GetPrefixesNative(
+    FallibleTArray<uint32_t>& aOutArray) {
+  MutexAutoLock lock(mLock);
+
+  if (!aOutArray.SetLength(mTotalPrefixes, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  uint32_t prefixIdxLength = mIndexPrefixes.Length();
+  uint32_t prefixCnt = 0;
+
+  for (uint32_t i = 0; i < prefixIdxLength; i++) {
+    uint32_t prefix = mIndexPrefixes[i];
+
+    if (prefixCnt >= mTotalPrefixes) {
+      return NS_ERROR_FAILURE;
+    }
+    aOutArray[prefixCnt++] = prefix;
+
+    if (mIndexDeltas.IsEmpty()) {
+      continue;
+    }
+
+    for (uint32_t j = 0; j < mIndexDeltas[i].Length(); j++) {
+      prefix += mIndexDeltas[i][j];
+      if (prefixCnt >= mTotalPrefixes) {
+        return NS_ERROR_FAILURE;
+      }
+      aOutArray[prefixCnt++] = prefix;
+    }
+  }
+
+  NS_ASSERTION(mTotalPrefixes == prefixCnt, "Lengths are inconsistent");
+  return NS_OK;
+}
+
+nsresult nsUrlClassifierPrefixSet::GetPrefixByIndex(
+    uint32_t aIndex, uint32_t* aOutPrefix) const {
+  NS_ENSURE_ARG_POINTER(aOutPrefix);
+
+  MutexAutoLock lock(mLock);
+  MOZ_ASSERT(aIndex < mTotalPrefixes);
+
+  // We can directly get the target index if the delta algorithm didn't apply.
+  if (mIndexDeltas.IsEmpty()) {
+    *aOutPrefix = mIndexPrefixes[aIndex];
+    return NS_OK;
+  }
+
+  // The prefix set was compressed by the delta algorithm, we have to iterate
+  // the delta index to find out the right bucket.
+  for (uint32_t i = 0; i < mIndexDeltas.Length(); i++) {
+    // The target index is in the current delta bucket.
+    if (aIndex <= mIndexDeltas[i].Length()) {
+      MOZ_ASSERT(aIndex <= DELTAS_LIMIT);
+
+      uint32_t prefix = mIndexPrefixes[i];
+
+      for (uint32_t j = 0; j < aIndex; j++) {
+        prefix += mIndexDeltas[i][j];
+      }
+
+      *aOutPrefix = prefix;
+      break;
+    }
+
+    aIndex -= mIndexDeltas[i].Length() + 1;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsUrlClassifierPrefixSet::GetPrefixes(uint32_t* aCount, uint32_t** aPrefixes) {
+  // No need to get mLock here because this function does not directly touch
+  // the class's data members. (GetPrefixesNative() will get mLock, however.)
+
+  NS_ENSURE_ARG_POINTER(aCount);
+  *aCount = 0;
+  NS_ENSURE_ARG_POINTER(aPrefixes);
+  *aPrefixes = nullptr;
+
+  FallibleTArray<uint32_t> prefixes;
+  nsresult rv = GetPrefixesNative(prefixes);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  uint64_t itemCount = prefixes.Length();
+  uint32_t* prefixArray =
+      static_cast<uint32_t*>(moz_xmalloc(itemCount * sizeof(uint32_t)));
+
+  memcpy(prefixArray, prefixes.Elements(), sizeof(uint32_t) * itemCount);
+
+  *aCount = itemCount;
+  *aPrefixes = prefixArray;
+
+  return NS_OK;
+}
+
+uint32_t nsUrlClassifierPrefixSet::BinSearch(uint32_t start, uint32_t end,
+                                             uint32_t target) const {
+  mLock.AssertCurrentThreadOwns();
+
+  while (start != end && end >= start) {
+    uint32_t i = start + ((end - start) >> 1);
+    uint32_t value = mIndexPrefixes[i];
+    if (value < target) {
+      start = i + 1;
+    } else if (value > target) {
+      end = i - 1;
+    } else {
+      return i;
+    }
+  }
+  return end;
+}
+
+NS_IMETHODIMP
+nsUrlClassifierPrefixSet::Contains(uint32_t aPrefix, bool* aFound) {
+  MutexAutoLock lock(mLock);
+
+  *aFound = false;
+
+  if (IsEmptyInternal()) {
+    return NS_OK;
+  }
+
+  uint32_t target = aPrefix;
+
+  // We want to do a "Price is Right" binary search, that is, we want to find
+  // the index of the value either equal to the target or the closest value
+  // that is less than the target.
+  //
+  if (target < mIndexPrefixes[0]) {
+    return NS_OK;
+  }
+
+  // |binsearch| does not necessarily return the correct index (when the
+  // target is not found) but rather it returns an index at least one away
+  // from the correct index.
+  // Because of this, we need to check if the target lies before the beginning
+  // of the indices.
+
+  uint32_t i = BinSearch(0, mIndexPrefixes.Length() - 1, target);
+  if (mIndexPrefixes[i] > target && i > 0) {
+    i--;
+  }
+
+  // Now search through the deltas for the target.
+  uint32_t diff = target - mIndexPrefixes[i];
+
+  if (!mIndexDeltas.IsEmpty()) {
+    uint32_t deltaSize = mIndexDeltas[i].Length();
+    uint32_t deltaIndex = 0;
+
+    while (diff > 0 && deltaIndex < deltaSize) {
+      diff -= mIndexDeltas[i][deltaIndex];
+      deltaIndex++;
+    }
+  }
+
+  if (diff == 0) {
+    *aFound = true;
+  }
+
+  return NS_OK;
+}
+
+size_t nsUrlClassifierPrefixSet::SizeOfIncludingThis(
+    mozilla::MallocSizeOf aMallocSizeOf) const {
+  MutexAutoLock lock(mLock);
+
+  size_t n = 0;
+  n += aMallocSizeOf(this);
+  n += mIndexDeltas.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  for (uint32_t i = 0; i < mIndexDeltas.Length(); i++) {
+    n += mIndexDeltas[i].ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+  n += mIndexPrefixes.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  return n;
+}
+
+bool nsUrlClassifierPrefixSet::IsEmptyInternal() const {
+  if (mIndexPrefixes.IsEmpty()) {
+    MOZ_ASSERT(mIndexDeltas.IsEmpty() && mTotalPrefixes == 0,
+               "If we're empty, there should be no leftovers.");
+    return true;
+  }
+
+  MOZ_ASSERT(mTotalPrefixes >= mIndexPrefixes.Length());
+  return false;
+}
+
+NS_IMETHODIMP
+nsUrlClassifierPrefixSet::IsEmpty(bool* aEmpty) {
+  MutexAutoLock lock(mLock);
+
+  *aEmpty = IsEmptyInternal();
+  return NS_OK;
+}
+
+nsresult nsUrlClassifierPrefixSet::LoadPrefixes(nsCOMPtr<nsIInputStream>& in) {
+  MutexAutoLock lock(mLock);
+
+  mCanary.Check();
+  Clear();
+
+  uint32_t magic;
+  uint32_t read;
+
+  nsresult rv =
+      in->Read(reinterpret_cast<char*>(&magic), sizeof(uint32_t), &read);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(read == sizeof(uint32_t), NS_ERROR_FAILURE);
+
+  if (magic == PREFIXSET_VERSION_MAGIC) {
+    // Read the number of indexed prefixes
+    uint32_t indexSize;
+    rv = in->Read(reinterpret_cast<char*>(&indexSize), sizeof(uint32_t), &read);
+    NS_ENSURE_SUCCESS(rv, rv);
+    NS_ENSURE_TRUE(read == sizeof(uint32_t), NS_ERROR_FAILURE);
+
+    // Read the number of delta prefixes
+    uint32_t deltaSize;
+    rv = in->Read(reinterpret_cast<char*>(&deltaSize), sizeof(uint32_t), &read);
+    NS_ENSURE_SUCCESS(rv, rv);
+    NS_ENSURE_TRUE(read == sizeof(uint32_t), NS_ERROR_FAILURE);
+
+    if (indexSize == 0) {
+      LOG(("[%s] Stored PrefixSet is empty!", mName.get()));
+      return NS_OK;
+    }
+
+    if (!mIndexPrefixes.SetLength(indexSize, fallible)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    mTotalPrefixes = indexSize;
+    if (deltaSize > (indexSize * DELTAS_LIMIT)) {
+      return NS_ERROR_FILE_CORRUPTED;
+    }
+
+    // Read index prefixes
+    uint32_t toRead = indexSize * sizeof(uint32_t);
+    rv = in->Read(reinterpret_cast<char*>(mIndexPrefixes.Elements()), toRead,
+                  &read);
+    NS_ENSURE_SUCCESS(rv, rv);
+    NS_ENSURE_TRUE(read == toRead, NS_ERROR_FAILURE);
+
+    if (deltaSize) {
+      nsTArray<uint32_t> indexStarts;
+
+      if (!indexStarts.SetLength(indexSize, fallible) ||
+          !mIndexDeltas.SetLength(indexSize, fallible)) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+
+      // Read index start array to construct mIndexDeltas
+      rv = in->Read(reinterpret_cast<char*>(indexStarts.Elements()), toRead,
+                    &read);
+      NS_ENSURE_SUCCESS(rv, rv);
+      NS_ENSURE_TRUE(read == toRead, NS_ERROR_FAILURE);
+
+      if (indexStarts[0] != 0) {
+        return NS_ERROR_FILE_CORRUPTED;
+      }
+
+      for (uint32_t i = 0; i < indexSize; i++) {
+        uint32_t numInDelta = i == indexSize - 1
+                                  ? deltaSize - indexStarts[i]
+                                  : indexStarts[i + 1] - indexStarts[i];
+        if (numInDelta > DELTAS_LIMIT) {
+          return NS_ERROR_FILE_CORRUPTED;
+        }
+        if (numInDelta > 0) {
+          if (!mIndexDeltas[i].SetLength(numInDelta, fallible)) {
+            return NS_ERROR_OUT_OF_MEMORY;
+          }
+          mTotalPrefixes += numInDelta;
+          toRead = numInDelta * sizeof(uint16_t);
+          rv = in->Read(reinterpret_cast<char*>(mIndexDeltas[i].Elements()),
+                        toRead, &read);
+          NS_ENSURE_SUCCESS(rv, rv);
+          NS_ENSURE_TRUE(read == toRead, NS_ERROR_FAILURE);
+        }
+      }
+    } else {
+      mIndexDeltas.Clear();
+    }
+  } else {
+    LOG(("[%s] Version magic mismatch, not loading", mName.get()));
+    return NS_ERROR_FILE_CORRUPTED;
+  }
+
+  MOZ_ASSERT_IF(mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mTotalPrefixes);
+  MOZ_ASSERT_IF(!mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mIndexDeltas.Length());
+  LOG(("[%s] Loading PrefixSet successful (%u total prefixes)", mName.get(),
+       mTotalPrefixes));
+
+  return NS_OK;
+}
+
+uint32_t nsUrlClassifierPrefixSet::CalculatePreallocateSize() const {
+  uint32_t fileSize = 4 * sizeof(uint32_t);
+  MutexAutoLock lock(mLock);
+
+  MOZ_RELEASE_ASSERT(mTotalPrefixes >= mIndexPrefixes.Length());
+  uint32_t deltas = mTotalPrefixes - mIndexPrefixes.Length();
+  fileSize += mIndexPrefixes.Length() * sizeof(uint32_t);
+  if (deltas) {
+    MOZ_ASSERT(mIndexPrefixes.Length() == mIndexDeltas.Length());
+
+    fileSize += mIndexPrefixes.Length() * sizeof(uint32_t);
+    fileSize += mIndexDeltas.Length() * sizeof(uint32_t);
+    fileSize += deltas * sizeof(uint16_t);
+  }
+  return fileSize;
+}
+
+uint32_t nsUrlClassifierPrefixSet::Length() const {
+  MutexAutoLock lock(mLock);
+
+  return mTotalPrefixes;
+}
+
+nsresult nsUrlClassifierPrefixSet::WritePrefixes(
+    nsCOMPtr<nsIOutputStream>& out) const {
+  MutexAutoLock lock(mLock);
+
+  MOZ_ASSERT_IF(mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mTotalPrefixes);
+  MOZ_ASSERT_IF(!mIndexDeltas.IsEmpty(),
+                mIndexPrefixes.Length() == mIndexDeltas.Length());
+
+  mCanary.Check();
+
+  uint32_t written;
+  uint32_t writelen = sizeof(uint32_t);
+  const uint32_t magic = PREFIXSET_VERSION_MAGIC;
+  nsresult rv =
+      out->Write(reinterpret_cast<const char*>(&magic), writelen, &written);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+
+  const uint32_t indexSize = mIndexPrefixes.Length();
+  if (mIndexDeltas.IsEmpty()) {
+    if (NS_WARN_IF(mTotalPrefixes != indexSize)) {
+      LOG(("[%s] mIndexPrefixes doesn't have the same length as mTotalPrefixes",
+           mName.get()));
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    if (NS_WARN_IF(mIndexDeltas.Length() != indexSize)) {
+      LOG(("[%s] mIndexPrefixes doesn't have the same length as mIndexDeltas",
+           mName.get()));
+      return NS_ERROR_FAILURE;
+    }
+  }
+  uint32_t totalDeltas = 0;
+
+  // Store the shape of mIndexDeltas by noting at which "count" of total
+  // indexes a new subarray starts. This is slightly cumbersome but keeps
+  // file format compatibility.
+  // If we ever update the format, we can gain space by storing the delta
+  // subarray sizes, which fit in bytes.
+  nsTArray<uint32_t> indexStarts;
+  if (!mIndexDeltas.IsEmpty()) {
+    if (!indexStarts.SetCapacity(indexSize + 1, fallible)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    indexStarts.AppendElement(0);
+
+    for (uint32_t i = 0; i < indexSize; i++) {
+      uint32_t deltaLength = mIndexDeltas[i].Length();
+      totalDeltas += deltaLength;
+      indexStarts.AppendElement(totalDeltas);
+    }
+    indexStarts.RemoveLastElement();  // we don't use the last element
+    MOZ_ASSERT(indexStarts.Length() == indexSize);
+  }
+
+  rv =
+      out->Write(reinterpret_cast<const char*>(&indexSize), writelen, &written);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+
+  rv = out->Write(reinterpret_cast<const char*>(&totalDeltas), writelen,
+                  &written);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+
+  writelen = indexSize * sizeof(uint32_t);
+  rv = out->Write(reinterpret_cast<const char*>(mIndexPrefixes.Elements()),
+                  writelen, &written);
+  NS_ENSURE_SUCCESS(rv, rv);
+  NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+
+  if (!mIndexDeltas.IsEmpty()) {
+    MOZ_ASSERT(!indexStarts.IsEmpty() && totalDeltas > 0);
+    rv = out->Write(reinterpret_cast<const char*>(indexStarts.Elements()),
+                    writelen, &written);
+    NS_ENSURE_SUCCESS(rv, rv);
+    NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+
+    for (uint32_t i = 0; i < indexSize; i++) {
+      writelen = mIndexDeltas[i].Length() * sizeof(uint16_t);
+      rv = out->Write(reinterpret_cast<const char*>(mIndexDeltas[i].Elements()),
+                      writelen, &written);
+      NS_ENSURE_SUCCESS(rv, rv);
+      NS_ENSURE_TRUE(written == writelen, NS_ERROR_FAILURE);
+    }
+  }
+
+  LOG(("[%s] Writing PrefixSet successful", mName.get()));
+
+  return NS_OK;
+}