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+/*
+ * 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/stringprintf.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));
+ }
+
+ std::string ToString() const {
+ if (ranges_.empty()) {
+ return "";
+ }
+ std::string result = std::to_string(ranges_.size() * 2);
+ for (const auto& r : ranges_) {
+ result += android::base::StringPrintf(",%zu,%zu", r.first, r.second);
+ }
+
+ return result;
+ }
+
+ // 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_;
+ }
+
+ protected:
+ // Actual limit for each value and the total number are both INT_MAX.
+ std::vector<Range> ranges_;
+ size_t blocks_;
+};
+
+static constexpr size_t kBlockSize = 4096;
+
+// The class is a sorted version of a RangeSet; and it's useful in imgdiff to split the input
+// files when we're handling large zip files. Specifically, we can treat the input file as a
+// continuous RangeSet (i.e. RangeSet("0-99") for a 100 blocks file); and break it down into
+// several smaller chunks based on the zip entries.
+
+// For example, [source: 0-99] can be split into
+// [split_src1: 10-29]; [split_src2: 40-49, 60-69]; [split_src3: 70-89]
+// Here "10-29" simply means block 10th to block 29th with respect to the original input file.
+// Also, note that the split sources should be mutual exclusive, but they don't need to cover
+// every block in the original source.
+class SortedRangeSet : public RangeSet {
+ public:
+ SortedRangeSet() {}
+
+ // Ranges in the the set should be mutually exclusive; and they're sorted by the start block.
+ explicit SortedRangeSet(std::vector<Range>&& pairs) : RangeSet(std::move(pairs)) {
+ std::sort(ranges_.begin(), ranges_.end());
+ }
+
+ void Insert(const Range& to_insert) {
+ SortedRangeSet rs({ to_insert });
+ Insert(rs);
+ }
+
+ // Insert the input SortedRangeSet; keep the ranges sorted and merge the overlap ranges.
+ void Insert(const SortedRangeSet& rs) {
+ if (rs.size() == 0) {
+ return;
+ }
+ // Merge and sort the two RangeSets.
+ std::vector<Range> temp = std::move(ranges_);
+ std::copy(rs.begin(), rs.end(), std::back_inserter(temp));
+ std::sort(temp.begin(), temp.end());
+
+ Clear();
+ // Trim overlaps and insert the result back to ranges_.
+ Range to_insert = temp.front();
+ for (auto it = temp.cbegin() + 1; it != temp.cend(); it++) {
+ if (it->first <= to_insert.second) {
+ to_insert.second = std::max(to_insert.second, it->second);
+ } else {
+ ranges_.push_back(to_insert);
+ blocks_ += (to_insert.second - to_insert.first);
+ to_insert = *it;
+ }
+ }
+ ranges_.push_back(to_insert);
+ blocks_ += (to_insert.second - to_insert.first);
+ }
+
+ void Clear() {
+ blocks_ = 0;
+ ranges_.clear();
+ }
+
+ using RangeSet::Overlaps;
+ bool Overlaps(size_t start, size_t len) const {
+ RangeSet rs({ { start / kBlockSize, (start + len - 1) / kBlockSize + 1 } });
+ return Overlaps(rs);
+ }
+
+ // Compute the block range the file occupies, and insert that range.
+ void Insert(size_t start, size_t len) {
+ Range to_insert{ start / kBlockSize, (start + len - 1) / kBlockSize + 1 };
+ Insert(to_insert);
+ }
+
+ // Given an offset of the file, checks if the corresponding block (by considering the file as
+ // 0-based continuous block ranges) is covered by the SortedRangeSet. If so, returns the offset
+ // within this SortedRangeSet.
+ //
+ // For example, the 4106-th byte of a file is from block 1, assuming a block size of 4096-byte.
+ // The mapped offset within a SortedRangeSet("1-9 15-19") is 10.
+ //
+ // An offset of 65546 falls into the 16-th block in a file. Block 16 is contained as the 10-th
+ // item in SortedRangeSet("1-9 15-19"). So its data can be found at offset 40970 (i.e. 4096 * 10
+ // + 10) in a range represented by this SortedRangeSet.
+ size_t GetOffsetInRangeSet(size_t old_offset) const {
+ size_t old_block_start = old_offset / kBlockSize;
+ size_t new_block_start = 0;
+ for (const auto& range : ranges_) {
+ // Find the index of old_block_start.
+ if (old_block_start >= range.second) {
+ new_block_start += (range.second - range.first);
+ } else if (old_block_start >= range.first) {
+ new_block_start += (old_block_start - range.first);
+ return (new_block_start * kBlockSize + old_offset % kBlockSize);
+ } else {
+ CHECK(false) << "block_start " << old_block_start
+ << " is missing between two ranges: " << this->ToString();
+ return 0;
+ }
+ }
+ CHECK(false) << "block_start " << old_block_start
+ << " exceeds the limit of current RangeSet: " << this->ToString();
+ return 0;
+ }
+}; \ No newline at end of file