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.

Header

Mercurial (22ced1a079e0)

VCS Links

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
//* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "ChunkSet.h"

namespace mozilla {
namespace safebrowsing {

const size_t ChunkSet::IO_BUFFER_SIZE;

nsresult ChunkSet::Serialize(nsACString& aChunkStr) {
  aChunkStr.Truncate();
  for (const Range& range : mRanges) {
    if (&range != &mRanges[0]) {
      aChunkStr.Append(',');
    }

    aChunkStr.AppendInt((int32_t)range.Begin());
    if (range.Begin() != range.End()) {
      aChunkStr.Append('-');
      aChunkStr.AppendInt((int32_t)range.End());
    }
  }

  return NS_OK;
}

nsresult ChunkSet::Set(uint32_t aChunk) {
  if (!Has(aChunk)) {
    Range chunkRange(aChunk, aChunk);

    if (mRanges.Length() == 0) {
      if (!mRanges.AppendElement(chunkRange, fallible)) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
      return NS_OK;
    }

    if (mRanges.LastElement().Precedes(chunkRange)) {
      mRanges.LastElement().End(aChunk);
    } else if (chunkRange.Precedes(mRanges[0])) {
      mRanges[0].Begin(aChunk);
    } else {
      ChunkSet tmp;
      if (!tmp.mRanges.AppendElement(chunkRange, fallible)) {
        return NS_ERROR_OUT_OF_MEMORY;
      }

      return Merge(tmp);
    }
  }

  return NS_OK;
}

bool ChunkSet::Has(uint32_t aChunk) const {
  size_t idx;
  return BinarySearchIf(mRanges, 0, mRanges.Length(),
                        Range::IntersectionComparator(Range(aChunk, aChunk)),
                        &idx);
  // IntersectionComparator works because we create a
  // single-chunk range.
}

nsresult ChunkSet::Merge(const ChunkSet& aOther) {
  size_t oldLen = mRanges.Length();

  for (const Range& mergeRange : aOther.mRanges) {
    if (!HasSubrange(mergeRange)) {
      if (!mRanges.InsertElementSorted(mergeRange, fallible)) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
    }
  }

  if (oldLen < mRanges.Length()) {
    for (size_t i = 1; i < mRanges.Length(); i++) {
      while (mRanges[i - 1].FoldLeft(mRanges[i])) {
        mRanges.RemoveElementAt(i);

        if (i == mRanges.Length()) {
          return NS_OK;
        }
      }
    }
  }

  return NS_OK;
}

uint32_t ChunkSet::Length() const {
  uint32_t len = 0;
  for (const Range& range : mRanges) {
    len += range.Length();
  }

  return len;
}

nsresult ChunkSet::Remove(const ChunkSet& aOther) {
  for (const Range& removalRange : aOther.mRanges) {
    if (mRanges.Length() == 0) {
      return NS_OK;
    }

    if (mRanges.LastElement().End() < removalRange.Begin() ||
        aOther.mRanges.LastElement().End() < mRanges[0].Begin()) {
      return NS_OK;
    }

    size_t intersectionIdx;
    while (BinarySearchIf(mRanges, 0, mRanges.Length(),
                          Range::IntersectionComparator(removalRange),
                          &intersectionIdx)) {
      ChunkSet remains;
      nsresult rv = mRanges[intersectionIdx].Remove(removalRange, remains);

      if (NS_FAILED(rv)) {
        return rv;
      }

      mRanges.RemoveElementAt(intersectionIdx);
      if (!mRanges.InsertElementsAt(intersectionIdx, remains.mRanges,
                                    fallible)) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
    }
  }

  return NS_OK;
}

void ChunkSet::Clear() { mRanges.Clear(); }

nsresult ChunkSet::Write(nsIOutputStream* aOut) const {
  nsTArray<uint32_t> chunks(IO_BUFFER_SIZE);

  for (const Range& range : mRanges) {
    for (uint32_t chunk = range.Begin(); chunk <= range.End(); chunk++) {
      chunks.AppendElement(chunk);

      if (chunks.Length() == chunks.Capacity()) {
        nsresult rv = WriteTArray(aOut, chunks);

        if (NS_FAILED(rv)) {
          return rv;
        }

        chunks.Clear();
      }
    }
  }

  nsresult rv = WriteTArray(aOut, chunks);

  if (NS_FAILED(rv)) {
    return rv;
  }

  return NS_OK;
}

nsresult ChunkSet::Read(nsIInputStream* aIn, uint32_t aNumElements) {
  nsTArray<uint32_t> chunks(IO_BUFFER_SIZE);

  while (aNumElements != 0) {
    chunks.Clear();

    uint32_t numToRead =
        aNumElements > IO_BUFFER_SIZE ? IO_BUFFER_SIZE : aNumElements;

    nsresult rv = ReadTArray(aIn, &chunks, numToRead);

    if (NS_FAILED(rv)) {
      return rv;
    }

    aNumElements -= numToRead;

    for (uint32_t c : chunks) {
      rv = Set(c);

      if (NS_FAILED(rv)) {
        return rv;
      }
    }
  }

  return NS_OK;
}

bool ChunkSet::HasSubrange(const Range& aSubrange) const {
  for (const Range& range : mRanges) {
    if (range.Contains(aSubrange)) {
      return true;
    } else if (!(aSubrange.Begin() > range.End() ||
                 range.Begin() > aSubrange.End())) {
      // In this case, aSubrange overlaps this range but is not a subrange.
      // because the ChunkSet implementation ensures that there are no
      // overlapping ranges, this means that aSubrange cannot be a subrange of
      // any of the following ranges
      return false;
    }
  }

  return false;
}

uint32_t ChunkSet::Range::Length() const { return mEnd - mBegin + 1; }

nsresult ChunkSet::Range::Remove(const Range& aRange,
                                 ChunkSet& aRemainderSet) const {
  if (mBegin < aRange.mBegin && aRange.mBegin <= mEnd) {
    // aRange overlaps & follows this range
    Range range(mBegin, aRange.mBegin - 1);
    if (!aRemainderSet.mRanges.AppendElement(range, fallible)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  if (mBegin <= aRange.mEnd && aRange.mEnd < mEnd) {
    // aRange overlaps & precedes this range
    Range range(aRange.mEnd + 1, mEnd);
    if (!aRemainderSet.mRanges.AppendElement(range, fallible)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  return NS_OK;
}

bool ChunkSet::Range::FoldLeft(const Range& aRange) {
  if (Contains(aRange)) {
    return true;
  } else if (Precedes(aRange) ||
             (mBegin <= aRange.mBegin && aRange.mBegin <= mEnd)) {
    mEnd = aRange.mEnd;
    return true;
  }

  return false;
}

}  // namespace safebrowsing
}  // namespace mozilla