139 lines
4.9 KiB
C++
139 lines
4.9 KiB
C++
/*
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* Copyright (C) 2020 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 specific language governing permissions and
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* limitations under the License.
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*/
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#include "zip_cd_entry_map.h"
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static uint32_t ComputeHash(std::string_view name) {
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return static_cast<uint32_t>(std::hash<std::string_view>{}(name));
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}
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template <typename ZipStringOffset>
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const std::string_view ToStringView(ZipStringOffset& entry, const uint8_t *start) {
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auto name = reinterpret_cast<const char*>(start + entry.name_offset);
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return std::string_view{name, entry.name_length};
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}
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// Convert a ZipEntry to a hash table index, verifying that it's in a valid range.
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template <typename ZipStringOffset>
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std::pair<ZipError, uint64_t> CdEntryMapZip32<ZipStringOffset>::GetCdEntryOffset(
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std::string_view name, const uint8_t* start) const {
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const uint32_t hash = ComputeHash(name);
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// NOTE: (hash_table_size - 1) is guaranteed to be non-negative.
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uint32_t ent = hash & (hash_table_size_ - 1);
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while (hash_table_[ent].name_offset != 0) {
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if (ToStringView(hash_table_[ent], start) == name) {
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return {kSuccess, static_cast<uint64_t>(hash_table_[ent].name_offset)};
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}
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ent = (ent + 1) & (hash_table_size_ - 1);
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}
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ALOGV("Zip: Unable to find entry %.*s", static_cast<int>(name.size()), name.data());
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return {kEntryNotFound, 0};
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}
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template <typename ZipStringOffset>
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ZipError CdEntryMapZip32<ZipStringOffset>::AddToMap(std::string_view name, const uint8_t* start) {
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const uint64_t hash = ComputeHash(name);
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uint32_t ent = hash & (hash_table_size_ - 1);
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/*
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* We over-allocated the table, so we're guaranteed to find an empty slot.
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* Further, we guarantee that the hashtable size is not 0.
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*/
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while (hash_table_[ent].name_offset != 0) {
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if (ToStringView(hash_table_[ent], start) == name) {
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// We've found a duplicate entry. We don't accept duplicates.
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ALOGW("Zip: Found duplicate entry %.*s", static_cast<int>(name.size()), name.data());
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return kDuplicateEntry;
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}
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ent = (ent + 1) & (hash_table_size_ - 1);
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}
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// `name` has already been validated before entry.
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const char* start_char = reinterpret_cast<const char*>(start);
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hash_table_[ent].name_offset = static_cast<uint32_t>(name.data() - start_char);
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hash_table_[ent].name_length = static_cast<uint16_t>(name.size());
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return kSuccess;
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}
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template <typename ZipStringOffset>
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void CdEntryMapZip32<ZipStringOffset>::ResetIteration() {
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current_position_ = 0;
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}
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template <typename ZipStringOffset>
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std::pair<std::string_view, uint64_t> CdEntryMapZip32<ZipStringOffset>::Next(
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const uint8_t* cd_start) {
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while (current_position_ < hash_table_size_) {
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const auto& entry = hash_table_[current_position_];
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current_position_ += 1;
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if (entry.name_offset != 0) {
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return {ToStringView(entry, cd_start), static_cast<uint64_t>(entry.name_offset)};
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}
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}
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// We have reached the end of the hash table.
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return {};
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}
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ZipError CdEntryMapZip64::AddToMap(std::string_view name, const uint8_t* start) {
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const auto [it, added] =
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entry_table_.insert({name, name.data() - reinterpret_cast<const char*>(start)});
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if (!added) {
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ALOGW("Zip: Found duplicate entry %.*s", static_cast<int>(name.size()), name.data());
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return kDuplicateEntry;
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}
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return kSuccess;
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}
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std::pair<ZipError, uint64_t> CdEntryMapZip64::GetCdEntryOffset(std::string_view name,
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const uint8_t* /*cd_start*/) const {
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const auto it = entry_table_.find(name);
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if (it == entry_table_.end()) {
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ALOGV("Zip: Could not find entry %.*s", static_cast<int>(name.size()), name.data());
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return {kEntryNotFound, 0};
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}
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return {kSuccess, it->second};
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}
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void CdEntryMapZip64::ResetIteration() {
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iterator_ = entry_table_.begin();
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}
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std::pair<std::string_view, uint64_t> CdEntryMapZip64::Next(const uint8_t* /*cd_start*/) {
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if (iterator_ == entry_table_.end()) {
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return {};
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}
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return *iterator_++;
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}
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std::unique_ptr<CdEntryMapInterface> CdEntryMapInterface::Create(uint64_t num_entries,
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size_t cd_length, uint16_t max_file_name_length) {
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using T = std::unique_ptr<CdEntryMapInterface>;
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if (num_entries > UINT16_MAX)
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return T(new CdEntryMapZip64());
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uint16_t num_entries_ = static_cast<uint16_t>(num_entries);
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if (cd_length > ZipStringOffset20::offset_max ||
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max_file_name_length > ZipStringOffset20::length_max) {
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return T(new CdEntryMapZip32<ZipStringOffset32>(num_entries_));
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}
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return T(new CdEntryMapZip32<ZipStringOffset20>(num_entries_));
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}
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