129 lines
3.9 KiB
C++
129 lines
3.9 KiB
C++
/*
|
|
* 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 <utility>
|
|
|
|
#include <errno.h>
|
|
|
|
namespace android {
|
|
namespace base {
|
|
|
|
static constexpr char kEmptyBuffer[] = {'0'};
|
|
|
|
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(borrowed_fd fd, off64_t offset, size_t length,
|
|
int prot) {
|
|
#if defined(_WIN32)
|
|
return FromOsHandle(reinterpret_cast<HANDLE>(_get_osfhandle(fd.get())), offset, length, prot);
|
|
#else
|
|
return FromOsHandle(fd.get(), offset, length, prot);
|
|
#endif
|
|
}
|
|
|
|
std::unique_ptr<MappedFile> MappedFile::FromOsHandle(os_handle h, off64_t offset, size_t length,
|
|
int prot) {
|
|
static const 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 = CreateFileMappingW(
|
|
h, 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 && ::GetLastError() == ERROR_FILE_INVALID) {
|
|
return std::unique_ptr<MappedFile>(
|
|
new MappedFile(const_cast<char*>(kEmptyBuffer), 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, h, 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(const_cast<char*>(kEmptyBuffer), 0, 0));
|
|
}
|
|
return nullptr;
|
|
}
|
|
return std::unique_ptr<MappedFile>(new MappedFile(static_cast<char*>(base), length, slop));
|
|
#endif
|
|
}
|
|
|
|
MappedFile::MappedFile(MappedFile&& other)
|
|
: base_(std::exchange(other.base_, nullptr)),
|
|
size_(std::exchange(other.size_, 0)),
|
|
offset_(std::exchange(other.offset_, 0))
|
|
#ifdef _WIN32
|
|
,
|
|
handle_(std::exchange(other.handle_, nullptr))
|
|
#endif
|
|
{
|
|
}
|
|
|
|
MappedFile& MappedFile::operator=(MappedFile&& other) {
|
|
Close();
|
|
base_ = std::exchange(other.base_, nullptr);
|
|
size_ = std::exchange(other.size_, 0);
|
|
offset_ = std::exchange(other.offset_, 0);
|
|
#ifdef _WIN32
|
|
handle_ = std::exchange(other.handle_, nullptr);
|
|
#endif
|
|
return *this;
|
|
}
|
|
|
|
MappedFile::~MappedFile() {
|
|
Close();
|
|
}
|
|
|
|
void MappedFile::Close() {
|
|
#if defined(_WIN32)
|
|
if (base_ != nullptr && size_ != 0) UnmapViewOfFile(base_);
|
|
if (handle_ != nullptr) CloseHandle(handle_);
|
|
handle_ = nullptr;
|
|
#else
|
|
if (base_ != nullptr && size_ != 0) munmap(base_, size_ + offset_);
|
|
#endif
|
|
|
|
base_ = nullptr;
|
|
offset_ = size_ = 0;
|
|
}
|
|
|
|
} // namespace base
|
|
} // namespace android
|