1 files changed, 164 insertions, 0 deletions
diff --git a/updater/include/updater/rangeset.h b/updater/include/updater/rangeset.h
new file mode 100644
index 000000000..fad038043
--- /dev/null
+++ b/updater/include/updater/rangeset.h
@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/strings.h>
+
+using Range = std::pair<size_t, size_t>;
+
+class RangeSet {
+ public:
+  RangeSet() : blocks_(0) {}
+
+  explicit RangeSet(std::vector<Range>&& pairs) {
+    CHECK_NE(pairs.size(), static_cast<size_t>(0)) << "Invalid number of tokens";
+
+    // Sanity check the input.
+    size_t result = 0;
+    for (const auto& range : pairs) {
+      CHECK_LT(range.first, range.second)
+          << "Empty or negative range: " << range.first << ", " << range.second;
+      size_t sz = range.second - range.first;
+      CHECK_LE(result, SIZE_MAX - sz) << "RangeSet size overflow";
+      result += sz;
+    }
+
+    ranges_ = pairs;
+    blocks_ = result;
+  }
+
+  static RangeSet Parse(const std::string& range_text) {
+    std::vector<std::string> pieces = android::base::Split(range_text, ",");
+    CHECK_GE(pieces.size(), static_cast<size_t>(3)) << "Invalid range text: " << range_text;
+
+    size_t num;
+    CHECK(android::base::ParseUint(pieces[0], &num, static_cast<size_t>(INT_MAX)))
+        << "Failed to parse the number of tokens: " << range_text;
+
+    CHECK_NE(num, static_cast<size_t>(0)) << "Invalid number of tokens: " << range_text;
+    CHECK_EQ(num % 2, static_cast<size_t>(0)) << "Number of tokens must be even: " << range_text;
+    CHECK_EQ(num, pieces.size() - 1) << "Mismatching number of tokens: " << range_text;
+
+    std::vector<Range> pairs;
+    for (size_t i = 0; i < num; i += 2) {
+      size_t first;
+      CHECK(android::base::ParseUint(pieces[i + 1], &first, static_cast<size_t>(INT_MAX)));
+      size_t second;
+      CHECK(android::base::ParseUint(pieces[i + 2], &second, static_cast<size_t>(INT_MAX)));
+
+      pairs.emplace_back(first, second);
+    }
+
+    return RangeSet(std::move(pairs));
+  }
+
+  // Get the block number for the i-th (starting from 0) block in the RangeSet.
+  size_t GetBlockNumber(size_t idx) const {
+    CHECK_LT(idx, blocks_) << "Out of bound index " << idx << " (total blocks: " << blocks_ << ")";
+
+    for (const auto& range : ranges_) {
+      if (idx < range.second - range.first) {
+        return range.first + idx;
+      }
+      idx -= (range.second - range.first);
+    }
+
+    CHECK(false) << "Failed to find block number for index " << idx;
+    return 0;  // Unreachable, but to make compiler happy.
+  }
+
+  // RangeSet has half-closed half-open bounds. For example, "3,5" contains blocks 3 and 4. So "3,5"
+  // and "5,7" are not overlapped.
+  bool Overlaps(const RangeSet& other) const {
+    for (const auto& range : ranges_) {
+      size_t start = range.first;
+      size_t end = range.second;
+      for (const auto& other_range : other.ranges_) {
+        size_t other_start = other_range.first;
+        size_t other_end = other_range.second;
+        // [start, end) vs [other_start, other_end)
+        if (!(other_start >= end || start >= other_end)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  // size() gives the number of Range's in this RangeSet.
+  size_t size() const {
+    return ranges_.size();
+  }
+
+  // blocks() gives the number of all blocks in this RangeSet.
+  size_t blocks() const {
+    return blocks_;
+  }
+
+  // We provide const iterators only.
+  std::vector<Range>::const_iterator cbegin() const {
+    return ranges_.cbegin();
+  }
+
+  std::vector<Range>::const_iterator cend() const {
+    return ranges_.cend();
+  }
+
+  // Need to provide begin()/end() since range-based loop expects begin()/end().
+  std::vector<Range>::const_iterator begin() const {
+    return ranges_.cbegin();
+  }
+
+  std::vector<Range>::const_iterator end() const {
+    return ranges_.cend();
+  }
+
+  // Reverse const iterators for MoveRange().
+  std::vector<Range>::const_reverse_iterator crbegin() const {
+    return ranges_.crbegin();
+  }
+
+  std::vector<Range>::const_reverse_iterator crend() const {
+    return ranges_.crend();
+  }
+
+  const Range& operator[](size_t i) const {
+    return ranges_[i];
+  }
+
+  bool operator==(const RangeSet& other) const {
+    // The orders of Range's matter. "4,1,5,8,10" != "4,8,10,1,5".
+    return (ranges_ == other.ranges_);
+  }
+
+  bool operator!=(const RangeSet& other) const {
+    return ranges_ != other.ranges_;
+  }
+
+ private:
+  // Actual limit for each value and the total number are both INT_MAX.
+  std::vector<Range> ranges_;
+  size_t blocks_;
+};