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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "linker_mapped_file_fragment.h"
#include "linker_debug.h"
#include <inttypes.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>
constexpr off64_t kPageMask = ~static_cast<off64_t>(PAGE_SIZE-1);
static off64_t page_start(off64_t offset) {
return offset & kPageMask;
}
static bool safe_add(off64_t* out, off64_t a, size_t b) {
CHECK(a >= 0);
if (static_cast<uint64_t>(INT64_MAX - a) < b) {
return false;
}
*out = a + b;
return true;
}
static size_t page_offset(off64_t offset) {
return static_cast<size_t>(offset & (PAGE_SIZE-1));
}
MappedFileFragment::MappedFileFragment() : map_start_(nullptr), map_size_(0),
data_(nullptr), size_ (0)
{ }
MappedFileFragment::~MappedFileFragment() {
if (map_start_ != nullptr) {
munmap(map_start_, map_size_);
}
}
bool MappedFileFragment::Map(int fd, off64_t base_offset, size_t elf_offset, size_t size) {
off64_t offset;
CHECK(safe_add(&offset, base_offset, elf_offset));
off64_t page_min = page_start(offset);
off64_t end_offset;
CHECK(safe_add(&end_offset, offset, size));
CHECK(safe_add(&end_offset, end_offset, page_offset(offset)));
size_t map_size = static_cast<size_t>(end_offset - page_min);
CHECK(map_size >= size);
uint8_t* map_start = static_cast<uint8_t*>(
mmap64(nullptr, map_size, PROT_READ, MAP_PRIVATE, fd, page_min));
if (map_start == MAP_FAILED) {
return false;
}
map_start_ = map_start;
map_size_ = map_size;
data_ = map_start + page_offset(offset);
size_ = size;
return true;
}
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