eb0ef145fd
Bug: http://b/119818070 "app crashes when reading asset of zero length" Test: ran tests Change-Id: Idd2ad6f6e72c8e445aff78a460fac96dea41c950
80 lines
2.5 KiB
C++
80 lines
2.5 KiB
C++
/*
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* Copyright (C) 2018 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 "android-base/mapped_file.h"
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#include <errno.h>
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namespace android {
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namespace base {
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static off64_t InitPageSize() {
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#if defined(_WIN32)
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SYSTEM_INFO si;
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GetSystemInfo(&si);
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return si.dwAllocationGranularity;
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#else
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return sysconf(_SC_PAGE_SIZE);
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#endif
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}
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std::unique_ptr<MappedFile> MappedFile::FromFd(int fd, off64_t offset, size_t length, int prot) {
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static off64_t page_size = InitPageSize();
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size_t slop = offset % page_size;
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off64_t file_offset = offset - slop;
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off64_t file_length = length + slop;
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#if defined(_WIN32)
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HANDLE handle =
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CreateFileMapping(reinterpret_cast<HANDLE>(_get_osfhandle(fd)), nullptr,
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(prot & PROT_WRITE) ? PAGE_READWRITE : PAGE_READONLY, 0, 0, nullptr);
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if (handle == nullptr) return nullptr;
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void* base = MapViewOfFile(handle, (prot & PROT_WRITE) ? FILE_MAP_ALL_ACCESS : FILE_MAP_READ, 0,
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file_offset, file_length);
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if (base == nullptr) {
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CloseHandle(handle);
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return nullptr;
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}
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return std::unique_ptr<MappedFile>(
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new MappedFile{static_cast<char*>(base), length, slop, handle});
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#else
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void* base = mmap(nullptr, file_length, prot, MAP_SHARED, fd, file_offset);
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if (base == MAP_FAILED) {
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// http://b/119818070 "app crashes when reading asset of zero length".
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// mmap fails with EINVAL for a zero length region.
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if (errno == EINVAL && length == 0) {
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return std::unique_ptr<MappedFile>(new MappedFile{nullptr, 0, 0});
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}
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return nullptr;
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}
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return std::unique_ptr<MappedFile>(new MappedFile{static_cast<char*>(base), length, slop});
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#endif
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}
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MappedFile::~MappedFile() {
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#if defined(_WIN32)
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if (base_ != nullptr) UnmapViewOfFile(base_);
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if (handle_ != nullptr) CloseHandle(handle_);
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#else
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if (base_ != nullptr) munmap(base_, size_);
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#endif
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base_ = nullptr;
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offset_ = size_ = 0;
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}
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} // namespace base
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} // namespace android
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