1 /*
2 * Copyright (C) 2019 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 specic language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "include/libfuse_jni/RedactionInfo.h"
18
19 using std::unique_ptr;
20 using std::vector;
21
22 namespace mediaprovider {
23 namespace fuse {
24
25 /**
26 * Merges any overlapping ranges into 1 range.
27 *
28 * Given ranges should be sorted, and they remain sorted.
29 */
mergeOverlappingRedactionRanges(vector<RedactionRange> & ranges)30 static void mergeOverlappingRedactionRanges(vector<RedactionRange>& ranges) {
31 int newRangesSize = ranges.size();
32 for (int i = 0; i < ranges.size() - 1; ++i) {
33 if (ranges[i].second >= ranges[i + 1].first) {
34 ranges[i + 1].first = ranges[i].first;
35 ranges[i + 1].second = std::max(ranges[i].second, ranges[i + 1].second);
36 // Invalidate the redundant range
37 ranges[i].first = LONG_MAX;
38 ranges[i].second = LONG_MAX;
39 newRangesSize--;
40 }
41 }
42 if (newRangesSize < ranges.size()) {
43 // Move invalid ranges to end of array
44 std::sort(ranges.begin(), ranges.end());
45 ranges.resize(newRangesSize);
46 }
47 }
48
49 /**
50 * Determine whether the read request overlaps with the redaction ranges
51 * defined by the given RedactionInfo.
52 *
53 * This function assumes redaction_ranges_ within RedactionInfo is sorted.
54 */
hasOverlapWithReadRequest(size_t size,off64_t off) const55 bool RedactionInfo::hasOverlapWithReadRequest(size_t size, off64_t off) const {
56 if (!isRedactionNeeded() || off > redaction_ranges_.back().second ||
57 off + size < redaction_ranges_.front().first) {
58 return false;
59 }
60 return true;
61 }
62
63 /**
64 * Sets the redaction ranges in RedactionInfo, sort the ranges and merge
65 * overlapping ranges.
66 */
processRedactionRanges(int redaction_ranges_num,const off64_t * redaction_ranges)67 void RedactionInfo::processRedactionRanges(int redaction_ranges_num,
68 const off64_t* redaction_ranges) {
69 redaction_ranges_.resize(redaction_ranges_num);
70 for (int i = 0; i < redaction_ranges_num; ++i) {
71 redaction_ranges_[i].first = static_cast<off64_t>(redaction_ranges[2 * i]);
72 redaction_ranges_[i].second = static_cast<off64_t>(redaction_ranges[2 * i + 1]);
73 }
74 std::sort(redaction_ranges_.begin(), redaction_ranges_.end());
75 mergeOverlappingRedactionRanges(redaction_ranges_);
76 }
77
size() const78 int RedactionInfo::size() const {
79 return redaction_ranges_.size();
80 }
81
isRedactionNeeded() const82 bool RedactionInfo::isRedactionNeeded() const {
83 return size() > 0;
84 }
85
RedactionInfo(int redaction_ranges_num,const off64_t * redaction_ranges)86 RedactionInfo::RedactionInfo(int redaction_ranges_num, const off64_t* redaction_ranges) {
87 if (redaction_ranges == 0) return;
88 processRedactionRanges(redaction_ranges_num, redaction_ranges);
89 }
90
getOverlappingRedactionRanges(size_t size,off64_t off) const91 unique_ptr<vector<RedactionRange>> RedactionInfo::getOverlappingRedactionRanges(size_t size,
92 off64_t off) const {
93 if (hasOverlapWithReadRequest(size, off)) {
94 auto first_redaction = redaction_ranges_.end();
95 auto last_redaction = redaction_ranges_.end();
96 for (auto iter = redaction_ranges_.begin(); iter != redaction_ranges_.end(); ++iter) {
97 const RedactionRange& rr = *iter;
98 // Look for the first range that overlaps with the read request
99 if (first_redaction == redaction_ranges_.end() && off <= rr.second &&
100 off + size >= rr.first) {
101 first_redaction = iter;
102 } else if (first_redaction != redaction_ranges_.end() && off + size < rr.first) {
103 // Once we're in the read request range, we start checking if
104 // we're out of it so we can return the result to the caller
105 break;
106 }
107 last_redaction = iter;
108 }
109 if (first_redaction != redaction_ranges_.end()) {
110 return std::make_unique<vector<RedactionRange>>(first_redaction, last_redaction + 1);
111 }
112 }
113 return std::make_unique<vector<RedactionRange>>();
114 }
115 } // namespace fuse
116 } // namespace mediaprovider
117