1 files changed, 248 insertions, 0 deletions
diff --git a/toolkit/components/url-classifier/ChunkSet.cpp b/toolkit/components/url-classifier/ChunkSet.cpp
new file mode 100644
index 0000000000..af488d43d7
--- /dev/null
+++ b/toolkit/components/url-classifier/ChunkSet.cpp
@@ -0,0 +1,248 @@
+//* -*- 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"
+
+#include "nsReadableUtils.h"
+
+namespace mozilla {
+namespace safebrowsing {
+
+const size_t ChunkSet::IO_BUFFER_SIZE;
+
+nsresult ChunkSet::Serialize(nsACString& aChunkStr) {
+  // Truncate and append rather than assigning because that's more efficient if
+  // aString is an nsAutoCString.
+  aChunkStr.Truncate();
+  StringJoinAppend(aChunkStr, ","_ns, mRanges,
+                   [](nsACString& dst, const Range& range) {
+                     dst.AppendInt((int32_t)range.Begin());
+                     if (range.Begin() != range.End()) {
+                       dst.Append('-');
+                       dst.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