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111 lines
3.6 KiB
111 lines
3.6 KiB
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specic language governing permissions and
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* limitations under the License.
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*/
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#ifndef MEDIA_PROVIDER_FUSE_REDACTIONINFO_H_
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#define MEDIA_PROVIDER_FUSE_REDACTIONINFO_H_
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#include <ostream>
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#include <vector>
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namespace mediaprovider {
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namespace fuse {
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/**
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* Type that represents a single redaction range within a file. Contains
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* a pair of offsets in the file, [start, end).
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*/
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typedef std::pair<off64_t, off64_t> RedactionRange;
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class ReadRange {
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public:
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ReadRange(off64_t s, size_t l, bool r) : start(s), size(l), is_redaction(r) {}
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const off64_t start;
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const size_t size;
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const bool is_redaction;
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bool operator==(const ReadRange& rhs) const {
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return start == rhs.start && size == rhs.size && is_redaction == rhs.is_redaction;
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}
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};
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class RedactionInfo {
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public:
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/**
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* Constructs a new instance of RedactionInfo based on the given redaction
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* ranges.
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*
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* @param redaction_ranges_num number of redaction ranges, essentially HALF
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* the size of the array redaction_ranges. If there are no redaction ranges,
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* this value must be set to 0.
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*
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* @param redaction_ranges array that defines the redaction ranges in
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* the following way:
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* redaction ranges n = [ redaction_ranges[2n], redaction_ranges[2n+1]]
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* This means that this array's length should be TWICE the value of
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* redaction_ranges_num
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*/
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RedactionInfo(int redaction_ranges_num, const off64_t* redaction_ranges);
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/**
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* Constructs a new instance of RedactionInfo with no redaction ranges.
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*/
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RedactionInfo() = default;
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/**
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* Calls d'tor for redactionRanges (vector).
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*/
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~RedactionInfo() = default;
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/**
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* Returns a set of ranges to fulfill a read request starting at |off| of size
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* |size|.
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*/
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void getReadRanges(off64_t off, size_t size, std::vector<ReadRange>* out) const;
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/**
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* Returns whether any ranges need to be redacted.
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*/
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bool isRedactionNeeded() const;
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/**
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* Returns number of redaction ranges.
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*/
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int size() const;
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private:
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/**
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* Calculates the redaction ranges that overlap with a given read request.
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* The read request is defined by its size and the offset of its first byte.
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*
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* <p>The returned ranges are guaranteed to be:
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* * Non-overlapping (with each other)
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* * Sorted in an ascending order of offset
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*
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* @param size size of the read request
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* @param off offset of the first byte of the read request
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* @return unique_ptr to a vector of RedactionRanges. If there are no
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* relevant redaction ranges, the vector will be empty.
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*/
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std::unique_ptr<std::vector<RedactionRange>> getOverlappingRedactionRanges(size_t size,
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off64_t off) const;
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std::vector<RedactionRange> redaction_ranges_;
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void processRedactionRanges(int redaction_ranges_num, const off64_t* redaction_ranges);
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bool hasOverlapWithReadRequest(size_t size, off64_t off) const;
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};
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} // namespace fuse
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} // namespace mediaprovider
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#endif // MEDIA_PROVIDER_FUSE_REDACTIONINFO_H_
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