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/*
* Copyright (C) 2018 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 "android-base/mapped_file.h"
#include <errno.h>
namespace android {
namespace base {
static off64_t InitPageSize() {
#if defined(_WIN32)
SYSTEM_INFO si;
GetSystemInfo(&si);
return si.dwAllocationGranularity;
#else
return sysconf(_SC_PAGE_SIZE);
#endif
}
std::unique_ptr<MappedFile> MappedFile::FromFd(int fd, off64_t offset, size_t length, int prot) {
static off64_t page_size = InitPageSize();
size_t slop = offset % page_size;
off64_t file_offset = offset - slop;
off64_t file_length = length + slop;
#if defined(_WIN32)
HANDLE handle =
CreateFileMapping(reinterpret_cast<HANDLE>(_get_osfhandle(fd)), nullptr,
(prot & PROT_WRITE) ? PAGE_READWRITE : PAGE_READONLY, 0, 0, nullptr);
if (handle == nullptr) {
// http://b/119818070 "app crashes when reading asset of zero length".
// Return a MappedFile that's only valid for reading the size.
if (length == 0) {
return std::unique_ptr<MappedFile>(new MappedFile{nullptr, 0, 0, nullptr});
}
return nullptr;
}
void* base = MapViewOfFile(handle, (prot & PROT_WRITE) ? FILE_MAP_ALL_ACCESS : FILE_MAP_READ, 0,
file_offset, file_length);
if (base == nullptr) {
CloseHandle(handle);
return nullptr;
}
return std::unique_ptr<MappedFile>(
new MappedFile{static_cast<char*>(base), length, slop, handle});
#else
void* base = mmap(nullptr, file_length, prot, MAP_SHARED, fd, file_offset);
if (base == MAP_FAILED) {
// http://b/119818070 "app crashes when reading asset of zero length".
// mmap fails with EINVAL for a zero length region.
if (errno == EINVAL && length == 0) {
return std::unique_ptr<MappedFile>(new MappedFile{nullptr, 0, 0});
}
return nullptr;
}
return std::unique_ptr<MappedFile>(new MappedFile{static_cast<char*>(base), length, slop});
#endif
}
MappedFile::~MappedFile() {
#if defined(_WIN32)
if (base_ != nullptr) UnmapViewOfFile(base_);
if (handle_ != nullptr) CloseHandle(handle_);
#else
if (base_ != nullptr) munmap(base_, size_ + offset_);
#endif
base_ = nullptr;
offset_ = size_ = 0;
}
} // namespace base
} // namespace android
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