78 lines
2.0 KiB
C++
78 lines
2.0 KiB
C++
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/*
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* Copyright (C) 2017 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 "berberis/base/mapped_file_fragment.h"
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#include <inttypes.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/user.h>
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#include <unistd.h>
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#include "berberis/base/checks.h"
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namespace {
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const off64_t kPageMask = ~static_cast<off64_t>(PAGE_SIZE - 1);
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off64_t page_start(off64_t offset) {
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return offset & kPageMask;
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}
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size_t page_offset(off64_t offset) {
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return static_cast<size_t>(offset & (PAGE_SIZE - 1));
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}
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} // namespace
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MappedFileFragment::MappedFileFragment()
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: map_start_(nullptr), map_size_(0), data_(nullptr), size_(0) {}
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MappedFileFragment::~MappedFileFragment() {
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if (map_start_ != nullptr) {
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munmap(map_start_, map_size_);
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}
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}
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bool MappedFileFragment::Map(int fd, off64_t base_offset, size_t elf_offset, size_t size) {
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off64_t offset;
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CHECK(!__builtin_add_overflow(base_offset, elf_offset, &offset));
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off64_t page_min = page_start(offset);
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off64_t end_offset;
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CHECK(!__builtin_add_overflow(offset, size, &end_offset));
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CHECK(!__builtin_add_overflow(end_offset, page_offset(offset), &end_offset));
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size_t map_size = static_cast<size_t>(end_offset - page_min);
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CHECK(map_size >= size);
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uint8_t* map_start =
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static_cast<uint8_t*>(mmap64(nullptr, map_size, PROT_READ, MAP_PRIVATE, fd, page_min));
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if (map_start == MAP_FAILED) {
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return false;
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}
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map_start_ = map_start;
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map_size_ = map_size;
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data_ = map_start + page_offset(offset);
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size_ = size;
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return true;
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}
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