d77c99ebc3
adb uses its own implementation of Windows HANDLE->int mapping, and it doesn't play well with _get_osfhandle() function used in MappedFile::FromFd(). This CL adds another function that accepts raw handle, so adb can pass it directly + make constant functions 'const' + make the MappedFile movable, as nothing prevents it from being one Test: libbase_test Change-Id: Ifde4a4094b910e9c7b431126ecf3fef5aa3bb4a6
127 lines
3.8 KiB
C++
127 lines
3.8 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 <utility>
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#include <errno.h>
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namespace android {
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namespace base {
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static constexpr char kEmptyBuffer[] = {'0'};
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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(borrowed_fd fd, off64_t offset, size_t length,
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int prot) {
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#if defined(_WIN32)
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auto file =
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FromOsHandle(reinterpret_cast<HANDLE>(_get_osfhandle(fd.get())), offset, length, prot);
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#else
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auto file = FromOsHandle(fd.get(), offset, length, prot);
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#endif
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return file ? std::make_unique<MappedFile>(std::move(file)) : std::unique_ptr<MappedFile>{};
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}
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MappedFile MappedFile::FromOsHandle(os_handle h, off64_t offset, size_t length, int prot) {
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static const 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 = CreateFileMappingW(
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h, nullptr, (prot & PROT_WRITE) ? PAGE_READWRITE : PAGE_READONLY, 0, 0, nullptr);
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if (handle == nullptr) {
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// http://b/119818070 "app crashes when reading asset of zero length".
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// Return a MappedFile that's only valid for reading the size.
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if (length == 0 && ::GetLastError() == ERROR_FILE_INVALID) {
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return MappedFile{const_cast<char*>(kEmptyBuffer), 0, 0, nullptr};
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}
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return MappedFile(nullptr, 0, 0, nullptr);
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}
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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 MappedFile(nullptr, 0, 0, nullptr);
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}
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return 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, h, 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 MappedFile{const_cast<char*>(kEmptyBuffer), 0, 0};
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}
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return MappedFile(nullptr, 0, 0);
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}
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return MappedFile{static_cast<char*>(base), length, slop};
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#endif
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}
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MappedFile::MappedFile(MappedFile&& other)
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: base_(std::exchange(other.base_, nullptr)),
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size_(std::exchange(other.size_, 0)),
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offset_(std::exchange(other.offset_, 0))
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#ifdef _WIN32
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,
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handle_(std::exchange(other.handle_, nullptr))
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#endif
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{
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}
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MappedFile& MappedFile::operator=(MappedFile&& other) {
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Close();
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base_ = std::exchange(other.base_, nullptr);
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size_ = std::exchange(other.size_, 0);
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offset_ = std::exchange(other.offset_, 0);
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#ifdef _WIN32
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handle_ = std::exchange(other.handle_, nullptr);
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#endif
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return *this;
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}
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MappedFile::~MappedFile() {
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Close();
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}
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void MappedFile::Close() {
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#if defined(_WIN32)
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if (base_ != nullptr && size_ != 0) UnmapViewOfFile(base_);
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if (handle_ != nullptr) CloseHandle(handle_);
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handle_ = nullptr;
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#else
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if (base_ != nullptr && size_ != 0) munmap(base_, size_ + offset_);
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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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