aboutsummaryrefslogtreecommitdiffstats
blob: a121a4efc00353b5519b43560b02611b5803b98f (plain) (blame)
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
/*
 * 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 <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>

RangeSet::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;
}

RangeSet 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 RangeSet::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 RangeSet::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 RangeSet::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;
}

static constexpr size_t kBlockSize = 4096;

// 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);
}

void SortedRangeSet::Clear() {
  blocks_ = 0;
  ranges_.clear();
}

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& 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;
}