extent_utils.cc revision d8b67f49d7f8ae291cd4fa901b2d3767137704e7 
1//
2// Copyright (C) 2009 The Android Open Source Project
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8//      http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15//
16
17#include "update_engine/payload_generator/extent_utils.h"
18
19#include <inttypes.h>
20
21#include <string>
22#include <utility>
23#include <vector>
24
25#include <base/logging.h>
26#include <base/macros.h>
27#include <base/strings/stringprintf.h>
28
29#include "update_engine/payload_consumer/payload_constants.h"
30#include "update_engine/payload_generator/annotated_operation.h"
31#include "update_engine/payload_generator/extent_ranges.h"
32
33using std::string;
34using std::vector;
35
36namespace chromeos_update_engine {
37
38void AppendBlockToExtents(vector<Extent>* extents, uint64_t block) {
39  // First try to extend the last extent in |extents|, if any.
40  if (!extents->empty()) {
41    Extent& extent = extents->back();
42    uint64_t next_block = extent.start_block() == kSparseHole ?
43        kSparseHole : extent.start_block() + extent.num_blocks();
44    if (next_block == block) {
45      extent.set_num_blocks(extent.num_blocks() + 1);
46      return;
47    }
48  }
49  // If unable to extend the last extent, append a new single-block extent.
50  Extent new_extent;
51  new_extent.set_start_block(block);
52  new_extent.set_num_blocks(1);
53  extents->push_back(new_extent);
54}
55
56void ExtendExtents(
57    google::protobuf::RepeatedPtrField<Extent>* extents,
58    const google::protobuf::RepeatedPtrField<Extent>& extents_to_add) {
59  vector<Extent> extents_vector;
60  vector<Extent> extents_to_add_vector;
61  ExtentsToVector(*extents, &extents_vector);
62  ExtentsToVector(extents_to_add, &extents_to_add_vector);
63  extents_vector.insert(extents_vector.end(),
64                        extents_to_add_vector.begin(),
65                        extents_to_add_vector.end());
66  NormalizeExtents(&extents_vector);
67  extents->Clear();
68  StoreExtents(extents_vector, extents);
69}
70
71// Stores all Extents in 'extents' into 'out'.
72void StoreExtents(const vector<Extent>& extents,
73                  google::protobuf::RepeatedPtrField<Extent>* out) {
74  for (const Extent& extent : extents) {
75    Extent* new_extent = out->Add();
76    *new_extent = extent;
77  }
78}
79
80// Stores all extents in |extents| into |out_vector|.
81void ExtentsToVector(const google::protobuf::RepeatedPtrField<Extent>& extents,
82                     vector<Extent>* out_vector) {
83  out_vector->clear();
84  for (int i = 0; i < extents.size(); i++) {
85    out_vector->push_back(extents.Get(i));
86  }
87}
88
89string ExtentsToString(const vector<Extent>& extents) {
90  string ext_str;
91  for (const Extent& e : extents)
92    ext_str += base::StringPrintf("[%" PRIu64 ", %" PRIu64 "] ",
93                                  static_cast<uint64_t>(e.start_block()),
94                                  static_cast<uint64_t>(e.num_blocks()));
95  return ext_str;
96}
97
98void NormalizeExtents(vector<Extent>* extents) {
99  vector<Extent> new_extents;
100  for (const Extent& curr_ext : *extents) {
101    if (new_extents.empty()) {
102      new_extents.push_back(curr_ext);
103      continue;
104    }
105    Extent& last_ext = new_extents.back();
106    if (last_ext.start_block() + last_ext.num_blocks() ==
107        curr_ext.start_block()) {
108      // If the extents are touching, we want to combine them.
109      last_ext.set_num_blocks(last_ext.num_blocks() + curr_ext.num_blocks());
110    } else {
111      // Otherwise just include the extent as is.
112      new_extents.push_back(curr_ext);
113    }
114  }
115  *extents = new_extents;
116}
117
118vector<Extent> ExtentsSublist(const vector<Extent>& extents,
119                              uint64_t block_offset, uint64_t block_count) {
120  vector<Extent> result;
121  uint64_t scanned_blocks = 0;
122  if (block_count == 0)
123    return result;
124  uint64_t end_block_offset = block_offset + block_count;
125  for (const Extent& extent : extents) {
126    // The loop invariant is that if |extents| has enough blocks, there's
127    // still some extent to add to |result|. This implies that at the beginning
128    // of the loop scanned_blocks < block_offset + block_count.
129    if (scanned_blocks + extent.num_blocks() > block_offset) {
130      // This case implies that |extent| has some overlapping with the requested
131      // subsequence.
132      uint64_t new_start = extent.start_block();
133      uint64_t new_num_blocks = extent.num_blocks();
134      if (scanned_blocks + new_num_blocks > end_block_offset) {
135        // Cut the end part of the extent.
136        new_num_blocks = end_block_offset - scanned_blocks;
137      }
138      if (block_offset > scanned_blocks) {
139        // Cut the begin part of the extent.
140        new_num_blocks -= block_offset - scanned_blocks;
141        new_start += block_offset - scanned_blocks;
142      }
143      result.push_back(ExtentForRange(new_start, new_num_blocks));
144    }
145    scanned_blocks += extent.num_blocks();
146    if (scanned_blocks >= end_block_offset)
147      break;
148  }
149  return result;
150}
151
152bool operator==(const Extent& a, const Extent& b) {
153  return a.start_block() == b.start_block() && a.num_blocks() == b.num_blocks();
154}
155
156}  // namespace chromeos_update_engine
157