/*
* 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.
*/
#include "otautil/rangeset.h"
#include <limits.h>
#include <stddef.h>
#include <algorithm>
#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>
RangeSet::RangeSet(std::vector<Range>&& pairs) {
blocks_ = 0;
if (pairs.empty()) {
LOG(ERROR) << "Invalid number of tokens";
return;
}
for (const auto& range : pairs) {
if (!PushBack(range)) {
Clear();
return;
}
}
}
RangeSet RangeSet::Parse(const std::string& range_text) {
std::vector<std::string> pieces = android::base::Split(range_text, ",");
if (pieces.size() < 3) {
LOG(ERROR) << "Invalid range text: " << range_text;
return {};
}
size_t num;
if (!android::base::ParseUint(pieces[0], &num, static_cast<size_t>(INT_MAX))) {
LOG(ERROR) << "Failed to parse the number of tokens: " << range_text;
return {};
}
if (num == 0) {
LOG(ERROR) << "Invalid number of tokens: " << range_text;
return {};
}
if (num % 2 != 0) {
LOG(ERROR) << "Number of tokens must be even: " << range_text;
return {};
}
if (num != pieces.size() - 1) {
LOG(ERROR) << "Mismatching number of tokens: " << range_text;
return {};
}
std::vector<Range> pairs;
for (size_t i = 0; i < num; i += 2) {
size_t first;
size_t second;
if (!android::base::ParseUint(pieces[i + 1], &first, static_cast<size_t>(INT_MAX)) ||
!android::base::ParseUint(pieces[i + 2], &second, static_cast<size_t>(INT_MAX))) {
return {};
}
pairs.emplace_back(first, second);
}
return RangeSet(std::move(pairs));
}
bool RangeSet::PushBack(Range range) {
if (range.first >= range.second) {
LOG(ERROR) << "Empty or negative range: " << range.first << ", " << range.second;
return false;
}
size_t sz = range.second - range.first;
if (blocks_ >= SIZE_MAX - sz) {
LOG(ERROR) << "RangeSet size overflow";
return false;
}
ranges_.push_back(std::move(range));
blocks_ += sz;
return true;
}
void RangeSet::Clear() {
ranges_.clear();
blocks_ = 0;
}
std::vector<RangeSet> RangeSet::Split(size_t groups) const {
if (ranges_.empty() || groups == 0) return {};
if (blocks_ < groups) {
groups = blocks_;
}
// Evenly distribute blocks, with the first few groups possibly containing one more.
size_t mean = blocks_ / groups;
std::vector<size_t> blocks_per_group(groups, mean);
std::fill_n(blocks_per_group.begin(), blocks_ % groups, mean + 1);
std::vector<RangeSet> result;
// Forward iterate Ranges and fill up each group with the desired number of blocks.
auto it = ranges_.cbegin();
Range range = *it;
for (const auto& blocks : blocks_per_group) {
RangeSet buffer;
size_t needed = blocks;
while (needed > 0) {
size_t range_blocks = range.second - range.first;
if (range_blocks > needed) {
// Split the current range and don't advance the iterator.
buffer.PushBack({ range.first, range.first + needed });
range.first = range.first + needed;
break;
}
buffer.PushBack(range);
it++;
if (it != ranges_.cend()) {
range = *it;
}
needed -= range_blocks;
}
result.push_back(std::move(buffer));
}
return result;
}
std::string RangeSet::ToString() const {
if (ranges_.empty()) {
return "";
}
std::string result = std::to_string(ranges_.size() * 2);
for (const auto& [begin, end] : ranges_) {
result += android::base::StringPrintf(",%zu,%zu", begin, end);
}
return result;
}
// Get the block number for the i-th (starting from 0) block in the RangeSet.
size_t RangeSet::GetBlockNumber(size_t idx) const {
CHECK_LT(idx, blocks_) << "Out of bound index " << idx << " (total blocks: " << blocks_ << ")";
for (const auto& [begin, end] : ranges_) {
if (idx < end - begin) {
return begin + idx;
}
idx -= (end - begin);
}
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 RangeSet::Overlaps(const RangeSet& other) const {
for (const auto& [begin, end] : ranges_) {
for (const auto& [other_begin, other_end] : other.ranges_) {
// [begin, end) vs [other_begin, other_end)
if (!(other_begin >= end || begin >= other_end)) {
return true;
}
}
}
return false;
}
std::optional<RangeSet> RangeSet::GetSubRanges(size_t start_index, size_t num_of_blocks) const {
size_t end_index = start_index + num_of_blocks; // The index of final block to read plus one
if (start_index > end_index || end_index > blocks_) {
LOG(ERROR) << "Failed to get the sub ranges for start_index " << start_index
<< " num_of_blocks " << num_of_blocks
<< " total number of blocks the range contains is " << blocks_;
return std::nullopt;
}
if (num_of_blocks == 0) {
LOG(WARNING) << "num_of_blocks is zero when calling GetSubRanges()";
return RangeSet();
}
RangeSet result;
size_t current_index = 0;
for (const auto& [range_start, range_end] : ranges_) {
CHECK_LT(range_start, range_end);
size_t blocks_in_range = range_end - range_start;
// Linear search to skip the ranges until we reach start_block.
if (current_index + blocks_in_range <= start_index) {
current_index += blocks_in_range;
continue;
}
size_t trimmed_range_start = range_start;
// We have found the first block range to read, trim the heading blocks.
if (current_index < start_index) {
trimmed_range_start += start_index - current_index;
}
// Trim the trailing blocks if the last range has more blocks than desired; also return the
// result.
if (current_index + blocks_in_range >= end_index) {
size_t trimmed_range_end = range_end - (current_index + blocks_in_range - end_index);
if (!result.PushBack({ trimmed_range_start, trimmed_range_end })) {
return std::nullopt;
}
return result;
}
if (!result.PushBack({ trimmed_range_start, range_end })) {
return std::nullopt;
}
current_index += blocks_in_range;
}
LOG(ERROR) << "Failed to construct byte ranges to read, start_block: " << start_index
<< ", num_of_blocks: " << num_of_blocks << " total number of blocks: " << blocks_;
return std::nullopt;
}
// Ranges in the the set should be mutually exclusive; and they're sorted by the start block.
SortedRangeSet::SortedRangeSet(std::vector<Range>&& pairs) : RangeSet(std::move(pairs)) {
std::sort(ranges_.begin(), ranges_.end());
}
void SortedRangeSet::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 SortedRangeSet::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);
}
// Compute the block range the file occupies, and insert that range.
void SortedRangeSet::Insert(size_t start, size_t len) {
Range to_insert{ start / kBlockSize, (start + len - 1) / kBlockSize + 1 };
Insert(to_insert);
}
bool SortedRangeSet::Overlaps(size_t start, size_t len) const {
RangeSet rs({ { start / kBlockSize, (start + len - 1) / kBlockSize + 1 } });
return Overlaps(rs);
}
// 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 SortedRangeSet::GetOffsetInRangeSet(size_t old_offset) const {
size_t old_block_start = old_offset / kBlockSize;
size_t new_block_start = 0;
for (const auto& [start, end] : ranges_) {
// Find the index of old_block_start.
if (old_block_start >= end) {
new_block_start += (end - start);
} else if (old_block_start >= start) {
new_block_start += (old_block_start - start);
return (new_block_start * kBlockSize + old_offset % kBlockSize);
} else {
CHECK(false) << "block_start " << old_block_start
<< " is missing between two ranges: " << ToString();
return 0;
}
}
CHECK(false) << "block_start " << old_block_start
<< " exceeds the limit of current RangeSet: " << ToString();
return 0;
}
